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40652 lines
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\input texinfo @c -*-texinfo-*-
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@c Copyright (C) 1988-1996, 1998-2012 Free Software Foundation, Inc.
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@c
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@c %**start of header
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@c makeinfo ignores cmds prev to setfilename, so its arg cannot make use
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@c of @set vars. However, you can override filename with makeinfo -o.
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@setfilename gdb.info
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@c
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@include gdb-cfg.texi
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@c
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@settitle Debugging with @value{GDBN}
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@setchapternewpage odd
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@c %**end of header
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@iftex
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@c @smallbook
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@c @cropmarks
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@end iftex
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@finalout
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@c To avoid file-name clashes between index.html and Index.html, when
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@c the manual is produced on a Posix host and then moved to a
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@c case-insensitive filesystem (e.g., MS-Windows), we separate the
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@c indices into two: Concept Index and all the rest.
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@syncodeindex ky fn
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@syncodeindex tp fn
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@c readline appendices use @vindex, @findex and @ftable,
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@c annotate.texi and gdbmi use @findex.
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@syncodeindex vr fn
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@syncodeindex fn fn
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@c !!set GDB manual's edition---not the same as GDB version!
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@c This is updated by GNU Press.
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@set EDITION Tenth
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@c !!set GDB edit command default editor
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@set EDITOR /bin/ex
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@c THIS MANUAL REQUIRES TEXINFO 4.0 OR LATER.
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@c This is a dir.info fragment to support semi-automated addition of
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@c manuals to an info tree.
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@dircategory Software development
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@direntry
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* Gdb: (gdb). The GNU debugger.
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@end direntry
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@copying
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Copyright @copyright{} 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996,
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1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
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2011, 2012
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Free Software Foundation, Inc.
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Permission is granted to copy, distribute and/or modify this document
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under the terms of the GNU Free Documentation License, Version 1.3 or
|
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any later version published by the Free Software Foundation; with the
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|
Invariant Sections being ``Free Software'' and ``Free Software Needs
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|
Free Documentation'', with the Front-Cover Texts being ``A GNU Manual,''
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and with the Back-Cover Texts as in (a) below.
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(a) The FSF's Back-Cover Text is: ``You are free to copy and modify
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this GNU Manual. Buying copies from GNU Press supports the FSF in
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developing GNU and promoting software freedom.''
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@end copying
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@ifnottex
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This file documents the @sc{gnu} debugger @value{GDBN}.
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This is the @value{EDITION} Edition, of @cite{Debugging with
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@value{GDBN}: the @sc{gnu} Source-Level Debugger} for @value{GDBN}
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@ifset VERSION_PACKAGE
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@value{VERSION_PACKAGE}
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@end ifset
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Version @value{GDBVN}.
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@insertcopying
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@end ifnottex
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@titlepage
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@title Debugging with @value{GDBN}
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@subtitle The @sc{gnu} Source-Level Debugger
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@sp 1
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@subtitle @value{EDITION} Edition, for @value{GDBN} version @value{GDBVN}
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@ifset VERSION_PACKAGE
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@sp 1
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@subtitle @value{VERSION_PACKAGE}
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@end ifset
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@author Richard Stallman, Roland Pesch, Stan Shebs, et al.
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@page
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@tex
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{\parskip=0pt
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\hfill (Send bugs and comments on @value{GDBN} to @value{BUGURL}.)\par
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\hfill {\it Debugging with @value{GDBN}}\par
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\hfill \TeX{}info \texinfoversion\par
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}
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@end tex
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@vskip 0pt plus 1filll
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Published by the Free Software Foundation @*
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51 Franklin Street, Fifth Floor,
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Boston, MA 02110-1301, USA@*
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ISBN 978-0-9831592-3-0 @*
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|
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@insertcopying
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@end titlepage
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@page
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@ifnottex
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@node Top, Summary, (dir), (dir)
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@top Debugging with @value{GDBN}
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This file describes @value{GDBN}, the @sc{gnu} symbolic debugger.
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This is the @value{EDITION} Edition, for @value{GDBN}
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@ifset VERSION_PACKAGE
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@value{VERSION_PACKAGE}
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@end ifset
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Version @value{GDBVN}.
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|
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Copyright (C) 1988-2012 Free Software Foundation, Inc.
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This edition of the GDB manual is dedicated to the memory of Fred
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Fish. Fred was a long-standing contributor to GDB and to Free
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|
software in general. We will miss him.
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@menu
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* Summary:: Summary of @value{GDBN}
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* Sample Session:: A sample @value{GDBN} session
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* Invocation:: Getting in and out of @value{GDBN}
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* Commands:: @value{GDBN} commands
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* Running:: Running programs under @value{GDBN}
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* Stopping:: Stopping and continuing
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* Reverse Execution:: Running programs backward
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|
* Process Record and Replay:: Recording inferior's execution and replaying it
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* Stack:: Examining the stack
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|
* Source:: Examining source files
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|
* Data:: Examining data
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|
* Optimized Code:: Debugging optimized code
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|
* Macros:: Preprocessor Macros
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* Tracepoints:: Debugging remote targets non-intrusively
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* Overlays:: Debugging programs that use overlays
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* Languages:: Using @value{GDBN} with different languages
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|
* Symbols:: Examining the symbol table
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|
* Altering:: Altering execution
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|
* GDB Files:: @value{GDBN} files
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|
* Targets:: Specifying a debugging target
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|
* Remote Debugging:: Debugging remote programs
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|
* Configurations:: Configuration-specific information
|
|
* Controlling GDB:: Controlling @value{GDBN}
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|
* Extending GDB:: Extending @value{GDBN}
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|
* Interpreters:: Command Interpreters
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|
* TUI:: @value{GDBN} Text User Interface
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|
* Emacs:: Using @value{GDBN} under @sc{gnu} Emacs
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|
* GDB/MI:: @value{GDBN}'s Machine Interface.
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|
* Annotations:: @value{GDBN}'s annotation interface.
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* JIT Interface:: Using the JIT debugging interface.
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|
* In-Process Agent:: In-Process Agent
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* GDB Bugs:: Reporting bugs in @value{GDBN}
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|
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@ifset SYSTEM_READLINE
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|
* Command Line Editing: (rluserman). Command Line Editing
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|
* Using History Interactively: (history). Using History Interactively
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@end ifset
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|
@ifclear SYSTEM_READLINE
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|
* Command Line Editing:: Command Line Editing
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|
* Using History Interactively:: Using History Interactively
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|
@end ifclear
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|
* In Memoriam:: In Memoriam
|
|
* Formatting Documentation:: How to format and print @value{GDBN} documentation
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|
* Installing GDB:: Installing GDB
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|
* Maintenance Commands:: Maintenance Commands
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|
* Remote Protocol:: GDB Remote Serial Protocol
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|
* Agent Expressions:: The GDB Agent Expression Mechanism
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|
* Target Descriptions:: How targets can describe themselves to
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@value{GDBN}
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|
* Operating System Information:: Getting additional information from
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|
the operating system
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|
* Trace File Format:: GDB trace file format
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|
* Index Section Format:: .gdb_index section format
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|
* Copying:: GNU General Public License says
|
|
how you can copy and share GDB
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|
* GNU Free Documentation License:: The license for this documentation
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|
* Concept Index:: Index of @value{GDBN} concepts
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|
* Command and Variable Index:: Index of @value{GDBN} commands, variables,
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|
functions, and Python data types
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|
@end menu
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|
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|
@end ifnottex
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|
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@contents
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@node Summary
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|
@unnumbered Summary of @value{GDBN}
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|
The purpose of a debugger such as @value{GDBN} is to allow you to see what is
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going on ``inside'' another program while it executes---or what another
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program was doing at the moment it crashed.
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@value{GDBN} can do four main kinds of things (plus other things in support of
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|
these) to help you catch bugs in the act:
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@itemize @bullet
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@item
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Start your program, specifying anything that might affect its behavior.
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@item
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Make your program stop on specified conditions.
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@item
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Examine what has happened, when your program has stopped.
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@item
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Change things in your program, so you can experiment with correcting the
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effects of one bug and go on to learn about another.
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@end itemize
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You can use @value{GDBN} to debug programs written in C and C@t{++}.
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For more information, see @ref{Supported Languages,,Supported Languages}.
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For more information, see @ref{C,,C and C++}.
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|
Support for D is partial. For information on D, see
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@ref{D,,D}.
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@cindex Modula-2
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|
Support for Modula-2 is partial. For information on Modula-2, see
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@ref{Modula-2,,Modula-2}.
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Support for OpenCL C is partial. For information on OpenCL C, see
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|
@ref{OpenCL C,,OpenCL C}.
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@cindex Pascal
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Debugging Pascal programs which use sets, subranges, file variables, or
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nested functions does not currently work. @value{GDBN} does not support
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entering expressions, printing values, or similar features using Pascal
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syntax.
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@cindex Fortran
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@value{GDBN} can be used to debug programs written in Fortran, although
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it may be necessary to refer to some variables with a trailing
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underscore.
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@value{GDBN} can be used to debug programs written in Objective-C,
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using either the Apple/NeXT or the GNU Objective-C runtime.
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@menu
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* Free Software:: Freely redistributable software
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* Free Documentation:: Free Software Needs Free Documentation
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* Contributors:: Contributors to GDB
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@end menu
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@node Free Software
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@unnumberedsec Free Software
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@value{GDBN} is @dfn{free software}, protected by the @sc{gnu}
|
|
General Public License
|
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(GPL). The GPL gives you the freedom to copy or adapt a licensed
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|
program---but every person getting a copy also gets with it the
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|
freedom to modify that copy (which means that they must get access to
|
|
the source code), and the freedom to distribute further copies.
|
|
Typical software companies use copyrights to limit your freedoms; the
|
|
Free Software Foundation uses the GPL to preserve these freedoms.
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|
Fundamentally, the General Public License is a license which says that
|
|
you have these freedoms and that you cannot take these freedoms away
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|
from anyone else.
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|
@node Free Documentation
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|
@unnumberedsec Free Software Needs Free Documentation
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|
The biggest deficiency in the free software community today is not in
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|
the software---it is the lack of good free documentation that we can
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|
include with the free software. Many of our most important
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|
programs do not come with free reference manuals and free introductory
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|
texts. Documentation is an essential part of any software package;
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|
when an important free software package does not come with a free
|
|
manual and a free tutorial, that is a major gap. We have many such
|
|
gaps today.
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|
Consider Perl, for instance. The tutorial manuals that people
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|
normally use are non-free. How did this come about? Because the
|
|
authors of those manuals published them with restrictive terms---no
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|
copying, no modification, source files not available---which exclude
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them from the free software world.
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|
That wasn't the first time this sort of thing happened, and it was far
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|
from the last. Many times we have heard a GNU user eagerly describe a
|
|
manual that he is writing, his intended contribution to the community,
|
|
only to learn that he had ruined everything by signing a publication
|
|
contract to make it non-free.
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|
Free documentation, like free software, is a matter of freedom, not
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|
price. The problem with the non-free manual is not that publishers
|
|
charge a price for printed copies---that in itself is fine. (The Free
|
|
Software Foundation sells printed copies of manuals, too.) The
|
|
problem is the restrictions on the use of the manual. Free manuals
|
|
are available in source code form, and give you permission to copy and
|
|
modify. Non-free manuals do not allow this.
|
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|
The criteria of freedom for a free manual are roughly the same as for
|
|
free software. Redistribution (including the normal kinds of
|
|
commercial redistribution) must be permitted, so that the manual can
|
|
accompany every copy of the program, both on-line and on paper.
|
|
|
|
Permission for modification of the technical content is crucial too.
|
|
When people modify the software, adding or changing features, if they
|
|
are conscientious they will change the manual too---so they can
|
|
provide accurate and clear documentation for the modified program. A
|
|
manual that leaves you no choice but to write a new manual to document
|
|
a changed version of the program is not really available to our
|
|
community.
|
|
|
|
Some kinds of limits on the way modification is handled are
|
|
acceptable. For example, requirements to preserve the original
|
|
author's copyright notice, the distribution terms, or the list of
|
|
authors, are ok. It is also no problem to require modified versions
|
|
to include notice that they were modified. Even entire sections that
|
|
may not be deleted or changed are acceptable, as long as they deal
|
|
with nontechnical topics (like this one). These kinds of restrictions
|
|
are acceptable because they don't obstruct the community's normal use
|
|
of the manual.
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|
However, it must be possible to modify all the @emph{technical}
|
|
content of the manual, and then distribute the result in all the usual
|
|
media, through all the usual channels. Otherwise, the restrictions
|
|
obstruct the use of the manual, it is not free, and we need another
|
|
manual to replace it.
|
|
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|
Please spread the word about this issue. Our community continues to
|
|
lose manuals to proprietary publishing. If we spread the word that
|
|
free software needs free reference manuals and free tutorials, perhaps
|
|
the next person who wants to contribute by writing documentation will
|
|
realize, before it is too late, that only free manuals contribute to
|
|
the free software community.
|
|
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|
If you are writing documentation, please insist on publishing it under
|
|
the GNU Free Documentation License or another free documentation
|
|
license. Remember that this decision requires your approval---you
|
|
don't have to let the publisher decide. Some commercial publishers
|
|
will use a free license if you insist, but they will not propose the
|
|
option; it is up to you to raise the issue and say firmly that this is
|
|
what you want. If the publisher you are dealing with refuses, please
|
|
try other publishers. If you're not sure whether a proposed license
|
|
is free, write to @email{licensing@@gnu.org}.
|
|
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|
You can encourage commercial publishers to sell more free, copylefted
|
|
manuals and tutorials by buying them, and particularly by buying
|
|
copies from the publishers that paid for their writing or for major
|
|
improvements. Meanwhile, try to avoid buying non-free documentation
|
|
at all. Check the distribution terms of a manual before you buy it,
|
|
and insist that whoever seeks your business must respect your freedom.
|
|
Check the history of the book, and try to reward the publishers that
|
|
have paid or pay the authors to work on it.
|
|
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|
The Free Software Foundation maintains a list of free documentation
|
|
published by other publishers, at
|
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@url{http://www.fsf.org/doc/other-free-books.html}.
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|
@node Contributors
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@unnumberedsec Contributors to @value{GDBN}
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|
Richard Stallman was the original author of @value{GDBN}, and of many
|
|
other @sc{gnu} programs. Many others have contributed to its
|
|
development. This section attempts to credit major contributors. One
|
|
of the virtues of free software is that everyone is free to contribute
|
|
to it; with regret, we cannot actually acknowledge everyone here. The
|
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file @file{ChangeLog} in the @value{GDBN} distribution approximates a
|
|
blow-by-blow account.
|
|
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|
Changes much prior to version 2.0 are lost in the mists of time.
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|
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|
@quotation
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@emph{Plea:} Additions to this section are particularly welcome. If you
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or your friends (or enemies, to be evenhanded) have been unfairly
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omitted from this list, we would like to add your names!
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@end quotation
|
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So that they may not regard their many labors as thankless, we
|
|
particularly thank those who shepherded @value{GDBN} through major
|
|
releases:
|
|
Andrew Cagney (releases 6.3, 6.2, 6.1, 6.0, 5.3, 5.2, 5.1 and 5.0);
|
|
Jim Blandy (release 4.18);
|
|
Jason Molenda (release 4.17);
|
|
Stan Shebs (release 4.14);
|
|
Fred Fish (releases 4.16, 4.15, 4.13, 4.12, 4.11, 4.10, and 4.9);
|
|
Stu Grossman and John Gilmore (releases 4.8, 4.7, 4.6, 4.5, and 4.4);
|
|
John Gilmore (releases 4.3, 4.2, 4.1, 4.0, and 3.9);
|
|
Jim Kingdon (releases 3.5, 3.4, and 3.3);
|
|
and Randy Smith (releases 3.2, 3.1, and 3.0).
|
|
|
|
Richard Stallman, assisted at various times by Peter TerMaat, Chris
|
|
Hanson, and Richard Mlynarik, handled releases through 2.8.
|
|
|
|
Michael Tiemann is the author of most of the @sc{gnu} C@t{++} support
|
|
in @value{GDBN}, with significant additional contributions from Per
|
|
Bothner and Daniel Berlin. James Clark wrote the @sc{gnu} C@t{++}
|
|
demangler. Early work on C@t{++} was by Peter TerMaat (who also did
|
|
much general update work leading to release 3.0).
|
|
|
|
@value{GDBN} uses the BFD subroutine library to examine multiple
|
|
object-file formats; BFD was a joint project of David V.
|
|
Henkel-Wallace, Rich Pixley, Steve Chamberlain, and John Gilmore.
|
|
|
|
David Johnson wrote the original COFF support; Pace Willison did
|
|
the original support for encapsulated COFF.
|
|
|
|
Brent Benson of Harris Computer Systems contributed DWARF 2 support.
|
|
|
|
Adam de Boor and Bradley Davis contributed the ISI Optimum V support.
|
|
Per Bothner, Noboyuki Hikichi, and Alessandro Forin contributed MIPS
|
|
support.
|
|
Jean-Daniel Fekete contributed Sun 386i support.
|
|
Chris Hanson improved the HP9000 support.
|
|
Noboyuki Hikichi and Tomoyuki Hasei contributed Sony/News OS 3 support.
|
|
David Johnson contributed Encore Umax support.
|
|
Jyrki Kuoppala contributed Altos 3068 support.
|
|
Jeff Law contributed HP PA and SOM support.
|
|
Keith Packard contributed NS32K support.
|
|
Doug Rabson contributed Acorn Risc Machine support.
|
|
Bob Rusk contributed Harris Nighthawk CX-UX support.
|
|
Chris Smith contributed Convex support (and Fortran debugging).
|
|
Jonathan Stone contributed Pyramid support.
|
|
Michael Tiemann contributed SPARC support.
|
|
Tim Tucker contributed support for the Gould NP1 and Gould Powernode.
|
|
Pace Willison contributed Intel 386 support.
|
|
Jay Vosburgh contributed Symmetry support.
|
|
Marko Mlinar contributed OpenRISC 1000 support.
|
|
|
|
Andreas Schwab contributed M68K @sc{gnu}/Linux support.
|
|
|
|
Rich Schaefer and Peter Schauer helped with support of SunOS shared
|
|
libraries.
|
|
|
|
Jay Fenlason and Roland McGrath ensured that @value{GDBN} and GAS agree
|
|
about several machine instruction sets.
|
|
|
|
Patrick Duval, Ted Goldstein, Vikram Koka and Glenn Engel helped develop
|
|
remote debugging. Intel Corporation, Wind River Systems, AMD, and ARM
|
|
contributed remote debugging modules for the i960, VxWorks, A29K UDI,
|
|
and RDI targets, respectively.
|
|
|
|
Brian Fox is the author of the readline libraries providing
|
|
command-line editing and command history.
|
|
|
|
Andrew Beers of SUNY Buffalo wrote the language-switching code, the
|
|
Modula-2 support, and contributed the Languages chapter of this manual.
|
|
|
|
Fred Fish wrote most of the support for Unix System Vr4.
|
|
He also enhanced the command-completion support to cover C@t{++} overloaded
|
|
symbols.
|
|
|
|
Hitachi America (now Renesas America), Ltd. sponsored the support for
|
|
H8/300, H8/500, and Super-H processors.
|
|
|
|
NEC sponsored the support for the v850, Vr4xxx, and Vr5xxx processors.
|
|
|
|
Mitsubishi (now Renesas) sponsored the support for D10V, D30V, and M32R/D
|
|
processors.
|
|
|
|
Toshiba sponsored the support for the TX39 Mips processor.
|
|
|
|
Matsushita sponsored the support for the MN10200 and MN10300 processors.
|
|
|
|
Fujitsu sponsored the support for SPARClite and FR30 processors.
|
|
|
|
Kung Hsu, Jeff Law, and Rick Sladkey added support for hardware
|
|
watchpoints.
|
|
|
|
Michael Snyder added support for tracepoints.
|
|
|
|
Stu Grossman wrote gdbserver.
|
|
|
|
Jim Kingdon, Peter Schauer, Ian Taylor, and Stu Grossman made
|
|
nearly innumerable bug fixes and cleanups throughout @value{GDBN}.
|
|
|
|
The following people at the Hewlett-Packard Company contributed
|
|
support for the PA-RISC 2.0 architecture, HP-UX 10.20, 10.30, and 11.0
|
|
(narrow mode), HP's implementation of kernel threads, HP's aC@t{++}
|
|
compiler, and the Text User Interface (nee Terminal User Interface):
|
|
Ben Krepp, Richard Title, John Bishop, Susan Macchia, Kathy Mann,
|
|
Satish Pai, India Paul, Steve Rehrauer, and Elena Zannoni. Kim Haase
|
|
provided HP-specific information in this manual.
|
|
|
|
DJ Delorie ported @value{GDBN} to MS-DOS, for the DJGPP project.
|
|
Robert Hoehne made significant contributions to the DJGPP port.
|
|
|
|
Cygnus Solutions has sponsored @value{GDBN} maintenance and much of its
|
|
development since 1991. Cygnus engineers who have worked on @value{GDBN}
|
|
fulltime include Mark Alexander, Jim Blandy, Per Bothner, Kevin
|
|
Buettner, Edith Epstein, Chris Faylor, Fred Fish, Martin Hunt, Jim
|
|
Ingham, John Gilmore, Stu Grossman, Kung Hsu, Jim Kingdon, John Metzler,
|
|
Fernando Nasser, Geoffrey Noer, Dawn Perchik, Rich Pixley, Zdenek
|
|
Radouch, Keith Seitz, Stan Shebs, David Taylor, and Elena Zannoni. In
|
|
addition, Dave Brolley, Ian Carmichael, Steve Chamberlain, Nick Clifton,
|
|
JT Conklin, Stan Cox, DJ Delorie, Ulrich Drepper, Frank Eigler, Doug
|
|
Evans, Sean Fagan, David Henkel-Wallace, Richard Henderson, Jeff
|
|
Holcomb, Jeff Law, Jim Lemke, Tom Lord, Bob Manson, Michael Meissner,
|
|
Jason Merrill, Catherine Moore, Drew Moseley, Ken Raeburn, Gavin
|
|
Romig-Koch, Rob Savoye, Jamie Smith, Mike Stump, Ian Taylor, Angela
|
|
Thomas, Michael Tiemann, Tom Tromey, Ron Unrau, Jim Wilson, and David
|
|
Zuhn have made contributions both large and small.
|
|
|
|
Andrew Cagney, Fernando Nasser, and Elena Zannoni, while working for
|
|
Cygnus Solutions, implemented the original @sc{gdb/mi} interface.
|
|
|
|
Jim Blandy added support for preprocessor macros, while working for Red
|
|
Hat.
|
|
|
|
Andrew Cagney designed @value{GDBN}'s architecture vector. Many
|
|
people including Andrew Cagney, Stephane Carrez, Randolph Chung, Nick
|
|
Duffek, Richard Henderson, Mark Kettenis, Grace Sainsbury, Kei
|
|
Sakamoto, Yoshinori Sato, Michael Snyder, Andreas Schwab, Jason
|
|
Thorpe, Corinna Vinschen, Ulrich Weigand, and Elena Zannoni, helped
|
|
with the migration of old architectures to this new framework.
|
|
|
|
Andrew Cagney completely re-designed and re-implemented @value{GDBN}'s
|
|
unwinder framework, this consisting of a fresh new design featuring
|
|
frame IDs, independent frame sniffers, and the sentinel frame. Mark
|
|
Kettenis implemented the @sc{dwarf 2} unwinder, Jeff Johnston the
|
|
libunwind unwinder, and Andrew Cagney the dummy, sentinel, tramp, and
|
|
trad unwinders. The architecture-specific changes, each involving a
|
|
complete rewrite of the architecture's frame code, were carried out by
|
|
Jim Blandy, Joel Brobecker, Kevin Buettner, Andrew Cagney, Stephane
|
|
Carrez, Randolph Chung, Orjan Friberg, Richard Henderson, Daniel
|
|
Jacobowitz, Jeff Johnston, Mark Kettenis, Theodore A. Roth, Kei
|
|
Sakamoto, Yoshinori Sato, Michael Snyder, Corinna Vinschen, and Ulrich
|
|
Weigand.
|
|
|
|
Christian Zankel, Ross Morley, Bob Wilson, and Maxim Grigoriev from
|
|
Tensilica, Inc.@: contributed support for Xtensa processors. Others
|
|
who have worked on the Xtensa port of @value{GDBN} in the past include
|
|
Steve Tjiang, John Newlin, and Scott Foehner.
|
|
|
|
Michael Eager and staff of Xilinx, Inc., contributed support for the
|
|
Xilinx MicroBlaze architecture.
|
|
|
|
@node Sample Session
|
|
@chapter A Sample @value{GDBN} Session
|
|
|
|
You can use this manual at your leisure to read all about @value{GDBN}.
|
|
However, a handful of commands are enough to get started using the
|
|
debugger. This chapter illustrates those commands.
|
|
|
|
@iftex
|
|
In this sample session, we emphasize user input like this: @b{input},
|
|
to make it easier to pick out from the surrounding output.
|
|
@end iftex
|
|
|
|
@c FIXME: this example may not be appropriate for some configs, where
|
|
@c FIXME...primary interest is in remote use.
|
|
|
|
One of the preliminary versions of @sc{gnu} @code{m4} (a generic macro
|
|
processor) exhibits the following bug: sometimes, when we change its
|
|
quote strings from the default, the commands used to capture one macro
|
|
definition within another stop working. In the following short @code{m4}
|
|
session, we define a macro @code{foo} which expands to @code{0000}; we
|
|
then use the @code{m4} built-in @code{defn} to define @code{bar} as the
|
|
same thing. However, when we change the open quote string to
|
|
@code{<QUOTE>} and the close quote string to @code{<UNQUOTE>}, the same
|
|
procedure fails to define a new synonym @code{baz}:
|
|
|
|
@smallexample
|
|
$ @b{cd gnu/m4}
|
|
$ @b{./m4}
|
|
@b{define(foo,0000)}
|
|
|
|
@b{foo}
|
|
0000
|
|
@b{define(bar,defn(`foo'))}
|
|
|
|
@b{bar}
|
|
0000
|
|
@b{changequote(<QUOTE>,<UNQUOTE>)}
|
|
|
|
@b{define(baz,defn(<QUOTE>foo<UNQUOTE>))}
|
|
@b{baz}
|
|
@b{Ctrl-d}
|
|
m4: End of input: 0: fatal error: EOF in string
|
|
@end smallexample
|
|
|
|
@noindent
|
|
Let us use @value{GDBN} to try to see what is going on.
|
|
|
|
@smallexample
|
|
$ @b{@value{GDBP} m4}
|
|
@c FIXME: this falsifies the exact text played out, to permit smallbook
|
|
@c FIXME... format to come out better.
|
|
@value{GDBN} is free software and you are welcome to distribute copies
|
|
of it under certain conditions; type "show copying" to see
|
|
the conditions.
|
|
There is absolutely no warranty for @value{GDBN}; type "show warranty"
|
|
for details.
|
|
|
|
@value{GDBN} @value{GDBVN}, Copyright 1999 Free Software Foundation, Inc...
|
|
(@value{GDBP})
|
|
@end smallexample
|
|
|
|
@noindent
|
|
@value{GDBN} reads only enough symbol data to know where to find the
|
|
rest when needed; as a result, the first prompt comes up very quickly.
|
|
We now tell @value{GDBN} to use a narrower display width than usual, so
|
|
that examples fit in this manual.
|
|
|
|
@smallexample
|
|
(@value{GDBP}) @b{set width 70}
|
|
@end smallexample
|
|
|
|
@noindent
|
|
We need to see how the @code{m4} built-in @code{changequote} works.
|
|
Having looked at the source, we know the relevant subroutine is
|
|
@code{m4_changequote}, so we set a breakpoint there with the @value{GDBN}
|
|
@code{break} command.
|
|
|
|
@smallexample
|
|
(@value{GDBP}) @b{break m4_changequote}
|
|
Breakpoint 1 at 0x62f4: file builtin.c, line 879.
|
|
@end smallexample
|
|
|
|
@noindent
|
|
Using the @code{run} command, we start @code{m4} running under @value{GDBN}
|
|
control; as long as control does not reach the @code{m4_changequote}
|
|
subroutine, the program runs as usual:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) @b{run}
|
|
Starting program: /work/Editorial/gdb/gnu/m4/m4
|
|
@b{define(foo,0000)}
|
|
|
|
@b{foo}
|
|
0000
|
|
@end smallexample
|
|
|
|
@noindent
|
|
To trigger the breakpoint, we call @code{changequote}. @value{GDBN}
|
|
suspends execution of @code{m4}, displaying information about the
|
|
context where it stops.
|
|
|
|
@smallexample
|
|
@b{changequote(<QUOTE>,<UNQUOTE>)}
|
|
|
|
Breakpoint 1, m4_changequote (argc=3, argv=0x33c70)
|
|
at builtin.c:879
|
|
879 if (bad_argc(TOKEN_DATA_TEXT(argv[0]),argc,1,3))
|
|
@end smallexample
|
|
|
|
@noindent
|
|
Now we use the command @code{n} (@code{next}) to advance execution to
|
|
the next line of the current function.
|
|
|
|
@smallexample
|
|
(@value{GDBP}) @b{n}
|
|
882 set_quotes((argc >= 2) ? TOKEN_DATA_TEXT(argv[1])\
|
|
: nil,
|
|
@end smallexample
|
|
|
|
@noindent
|
|
@code{set_quotes} looks like a promising subroutine. We can go into it
|
|
by using the command @code{s} (@code{step}) instead of @code{next}.
|
|
@code{step} goes to the next line to be executed in @emph{any}
|
|
subroutine, so it steps into @code{set_quotes}.
|
|
|
|
@smallexample
|
|
(@value{GDBP}) @b{s}
|
|
set_quotes (lq=0x34c78 "<QUOTE>", rq=0x34c88 "<UNQUOTE>")
|
|
at input.c:530
|
|
530 if (lquote != def_lquote)
|
|
@end smallexample
|
|
|
|
@noindent
|
|
The display that shows the subroutine where @code{m4} is now
|
|
suspended (and its arguments) is called a stack frame display. It
|
|
shows a summary of the stack. We can use the @code{backtrace}
|
|
command (which can also be spelled @code{bt}), to see where we are
|
|
in the stack as a whole: the @code{backtrace} command displays a
|
|
stack frame for each active subroutine.
|
|
|
|
@smallexample
|
|
(@value{GDBP}) @b{bt}
|
|
#0 set_quotes (lq=0x34c78 "<QUOTE>", rq=0x34c88 "<UNQUOTE>")
|
|
at input.c:530
|
|
#1 0x6344 in m4_changequote (argc=3, argv=0x33c70)
|
|
at builtin.c:882
|
|
#2 0x8174 in expand_macro (sym=0x33320) at macro.c:242
|
|
#3 0x7a88 in expand_token (obs=0x0, t=209696, td=0xf7fffa30)
|
|
at macro.c:71
|
|
#4 0x79dc in expand_input () at macro.c:40
|
|
#5 0x2930 in main (argc=0, argv=0xf7fffb20) at m4.c:195
|
|
@end smallexample
|
|
|
|
@noindent
|
|
We step through a few more lines to see what happens. The first two
|
|
times, we can use @samp{s}; the next two times we use @code{n} to avoid
|
|
falling into the @code{xstrdup} subroutine.
|
|
|
|
@smallexample
|
|
(@value{GDBP}) @b{s}
|
|
0x3b5c 532 if (rquote != def_rquote)
|
|
(@value{GDBP}) @b{s}
|
|
0x3b80 535 lquote = (lq == nil || *lq == '\0') ? \
|
|
def_lquote : xstrdup(lq);
|
|
(@value{GDBP}) @b{n}
|
|
536 rquote = (rq == nil || *rq == '\0') ? def_rquote\
|
|
: xstrdup(rq);
|
|
(@value{GDBP}) @b{n}
|
|
538 len_lquote = strlen(rquote);
|
|
@end smallexample
|
|
|
|
@noindent
|
|
The last line displayed looks a little odd; we can examine the variables
|
|
@code{lquote} and @code{rquote} to see if they are in fact the new left
|
|
and right quotes we specified. We use the command @code{p}
|
|
(@code{print}) to see their values.
|
|
|
|
@smallexample
|
|
(@value{GDBP}) @b{p lquote}
|
|
$1 = 0x35d40 "<QUOTE>"
|
|
(@value{GDBP}) @b{p rquote}
|
|
$2 = 0x35d50 "<UNQUOTE>"
|
|
@end smallexample
|
|
|
|
@noindent
|
|
@code{lquote} and @code{rquote} are indeed the new left and right quotes.
|
|
To look at some context, we can display ten lines of source
|
|
surrounding the current line with the @code{l} (@code{list}) command.
|
|
|
|
@smallexample
|
|
(@value{GDBP}) @b{l}
|
|
533 xfree(rquote);
|
|
534
|
|
535 lquote = (lq == nil || *lq == '\0') ? def_lquote\
|
|
: xstrdup (lq);
|
|
536 rquote = (rq == nil || *rq == '\0') ? def_rquote\
|
|
: xstrdup (rq);
|
|
537
|
|
538 len_lquote = strlen(rquote);
|
|
539 len_rquote = strlen(lquote);
|
|
540 @}
|
|
541
|
|
542 void
|
|
@end smallexample
|
|
|
|
@noindent
|
|
Let us step past the two lines that set @code{len_lquote} and
|
|
@code{len_rquote}, and then examine the values of those variables.
|
|
|
|
@smallexample
|
|
(@value{GDBP}) @b{n}
|
|
539 len_rquote = strlen(lquote);
|
|
(@value{GDBP}) @b{n}
|
|
540 @}
|
|
(@value{GDBP}) @b{p len_lquote}
|
|
$3 = 9
|
|
(@value{GDBP}) @b{p len_rquote}
|
|
$4 = 7
|
|
@end smallexample
|
|
|
|
@noindent
|
|
That certainly looks wrong, assuming @code{len_lquote} and
|
|
@code{len_rquote} are meant to be the lengths of @code{lquote} and
|
|
@code{rquote} respectively. We can set them to better values using
|
|
the @code{p} command, since it can print the value of
|
|
any expression---and that expression can include subroutine calls and
|
|
assignments.
|
|
|
|
@smallexample
|
|
(@value{GDBP}) @b{p len_lquote=strlen(lquote)}
|
|
$5 = 7
|
|
(@value{GDBP}) @b{p len_rquote=strlen(rquote)}
|
|
$6 = 9
|
|
@end smallexample
|
|
|
|
@noindent
|
|
Is that enough to fix the problem of using the new quotes with the
|
|
@code{m4} built-in @code{defn}? We can allow @code{m4} to continue
|
|
executing with the @code{c} (@code{continue}) command, and then try the
|
|
example that caused trouble initially:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) @b{c}
|
|
Continuing.
|
|
|
|
@b{define(baz,defn(<QUOTE>foo<UNQUOTE>))}
|
|
|
|
baz
|
|
0000
|
|
@end smallexample
|
|
|
|
@noindent
|
|
Success! The new quotes now work just as well as the default ones. The
|
|
problem seems to have been just the two typos defining the wrong
|
|
lengths. We allow @code{m4} exit by giving it an EOF as input:
|
|
|
|
@smallexample
|
|
@b{Ctrl-d}
|
|
Program exited normally.
|
|
@end smallexample
|
|
|
|
@noindent
|
|
The message @samp{Program exited normally.} is from @value{GDBN}; it
|
|
indicates @code{m4} has finished executing. We can end our @value{GDBN}
|
|
session with the @value{GDBN} @code{quit} command.
|
|
|
|
@smallexample
|
|
(@value{GDBP}) @b{quit}
|
|
@end smallexample
|
|
|
|
@node Invocation
|
|
@chapter Getting In and Out of @value{GDBN}
|
|
|
|
This chapter discusses how to start @value{GDBN}, and how to get out of it.
|
|
The essentials are:
|
|
@itemize @bullet
|
|
@item
|
|
type @samp{@value{GDBP}} to start @value{GDBN}.
|
|
@item
|
|
type @kbd{quit} or @kbd{Ctrl-d} to exit.
|
|
@end itemize
|
|
|
|
@menu
|
|
* Invoking GDB:: How to start @value{GDBN}
|
|
* Quitting GDB:: How to quit @value{GDBN}
|
|
* Shell Commands:: How to use shell commands inside @value{GDBN}
|
|
* Logging Output:: How to log @value{GDBN}'s output to a file
|
|
@end menu
|
|
|
|
@node Invoking GDB
|
|
@section Invoking @value{GDBN}
|
|
|
|
Invoke @value{GDBN} by running the program @code{@value{GDBP}}. Once started,
|
|
@value{GDBN} reads commands from the terminal until you tell it to exit.
|
|
|
|
You can also run @code{@value{GDBP}} with a variety of arguments and options,
|
|
to specify more of your debugging environment at the outset.
|
|
|
|
The command-line options described here are designed
|
|
to cover a variety of situations; in some environments, some of these
|
|
options may effectively be unavailable.
|
|
|
|
The most usual way to start @value{GDBN} is with one argument,
|
|
specifying an executable program:
|
|
|
|
@smallexample
|
|
@value{GDBP} @var{program}
|
|
@end smallexample
|
|
|
|
@noindent
|
|
You can also start with both an executable program and a core file
|
|
specified:
|
|
|
|
@smallexample
|
|
@value{GDBP} @var{program} @var{core}
|
|
@end smallexample
|
|
|
|
You can, instead, specify a process ID as a second argument, if you want
|
|
to debug a running process:
|
|
|
|
@smallexample
|
|
@value{GDBP} @var{program} 1234
|
|
@end smallexample
|
|
|
|
@noindent
|
|
would attach @value{GDBN} to process @code{1234} (unless you also have a file
|
|
named @file{1234}; @value{GDBN} does check for a core file first).
|
|
|
|
Taking advantage of the second command-line argument requires a fairly
|
|
complete operating system; when you use @value{GDBN} as a remote
|
|
debugger attached to a bare board, there may not be any notion of
|
|
``process'', and there is often no way to get a core dump. @value{GDBN}
|
|
will warn you if it is unable to attach or to read core dumps.
|
|
|
|
You can optionally have @code{@value{GDBP}} pass any arguments after the
|
|
executable file to the inferior using @code{--args}. This option stops
|
|
option processing.
|
|
@smallexample
|
|
@value{GDBP} --args gcc -O2 -c foo.c
|
|
@end smallexample
|
|
This will cause @code{@value{GDBP}} to debug @code{gcc}, and to set
|
|
@code{gcc}'s command-line arguments (@pxref{Arguments}) to @samp{-O2 -c foo.c}.
|
|
|
|
You can run @code{@value{GDBP}} without printing the front material, which describes
|
|
@value{GDBN}'s non-warranty, by specifying @code{-silent}:
|
|
|
|
@smallexample
|
|
@value{GDBP} -silent
|
|
@end smallexample
|
|
|
|
@noindent
|
|
You can further control how @value{GDBN} starts up by using command-line
|
|
options. @value{GDBN} itself can remind you of the options available.
|
|
|
|
@noindent
|
|
Type
|
|
|
|
@smallexample
|
|
@value{GDBP} -help
|
|
@end smallexample
|
|
|
|
@noindent
|
|
to display all available options and briefly describe their use
|
|
(@samp{@value{GDBP} -h} is a shorter equivalent).
|
|
|
|
All options and command line arguments you give are processed
|
|
in sequential order. The order makes a difference when the
|
|
@samp{-x} option is used.
|
|
|
|
|
|
@menu
|
|
* File Options:: Choosing files
|
|
* Mode Options:: Choosing modes
|
|
* Startup:: What @value{GDBN} does during startup
|
|
@end menu
|
|
|
|
@node File Options
|
|
@subsection Choosing Files
|
|
|
|
When @value{GDBN} starts, it reads any arguments other than options as
|
|
specifying an executable file and core file (or process ID). This is
|
|
the same as if the arguments were specified by the @samp{-se} and
|
|
@samp{-c} (or @samp{-p}) options respectively. (@value{GDBN} reads the
|
|
first argument that does not have an associated option flag as
|
|
equivalent to the @samp{-se} option followed by that argument; and the
|
|
second argument that does not have an associated option flag, if any, as
|
|
equivalent to the @samp{-c}/@samp{-p} option followed by that argument.)
|
|
If the second argument begins with a decimal digit, @value{GDBN} will
|
|
first attempt to attach to it as a process, and if that fails, attempt
|
|
to open it as a corefile. If you have a corefile whose name begins with
|
|
a digit, you can prevent @value{GDBN} from treating it as a pid by
|
|
prefixing it with @file{./}, e.g.@: @file{./12345}.
|
|
|
|
If @value{GDBN} has not been configured to included core file support,
|
|
such as for most embedded targets, then it will complain about a second
|
|
argument and ignore it.
|
|
|
|
Many options have both long and short forms; both are shown in the
|
|
following list. @value{GDBN} also recognizes the long forms if you truncate
|
|
them, so long as enough of the option is present to be unambiguous.
|
|
(If you prefer, you can flag option arguments with @samp{--} rather
|
|
than @samp{-}, though we illustrate the more usual convention.)
|
|
|
|
@c NOTE: the @cindex entries here use double dashes ON PURPOSE. This
|
|
@c way, both those who look for -foo and --foo in the index, will find
|
|
@c it.
|
|
|
|
@table @code
|
|
@item -symbols @var{file}
|
|
@itemx -s @var{file}
|
|
@cindex @code{--symbols}
|
|
@cindex @code{-s}
|
|
Read symbol table from file @var{file}.
|
|
|
|
@item -exec @var{file}
|
|
@itemx -e @var{file}
|
|
@cindex @code{--exec}
|
|
@cindex @code{-e}
|
|
Use file @var{file} as the executable file to execute when appropriate,
|
|
and for examining pure data in conjunction with a core dump.
|
|
|
|
@item -se @var{file}
|
|
@cindex @code{--se}
|
|
Read symbol table from file @var{file} and use it as the executable
|
|
file.
|
|
|
|
@item -core @var{file}
|
|
@itemx -c @var{file}
|
|
@cindex @code{--core}
|
|
@cindex @code{-c}
|
|
Use file @var{file} as a core dump to examine.
|
|
|
|
@item -pid @var{number}
|
|
@itemx -p @var{number}
|
|
@cindex @code{--pid}
|
|
@cindex @code{-p}
|
|
Connect to process ID @var{number}, as with the @code{attach} command.
|
|
|
|
@item -command @var{file}
|
|
@itemx -x @var{file}
|
|
@cindex @code{--command}
|
|
@cindex @code{-x}
|
|
Execute commands from file @var{file}. The contents of this file is
|
|
evaluated exactly as the @code{source} command would.
|
|
@xref{Command Files,, Command files}.
|
|
|
|
@item -eval-command @var{command}
|
|
@itemx -ex @var{command}
|
|
@cindex @code{--eval-command}
|
|
@cindex @code{-ex}
|
|
Execute a single @value{GDBN} command.
|
|
|
|
This option may be used multiple times to call multiple commands. It may
|
|
also be interleaved with @samp{-command} as required.
|
|
|
|
@smallexample
|
|
@value{GDBP} -ex 'target sim' -ex 'load' \
|
|
-x setbreakpoints -ex 'run' a.out
|
|
@end smallexample
|
|
|
|
@item -init-command @var{file}
|
|
@itemx -ix @var{file}
|
|
@cindex @code{--init-command}
|
|
@cindex @code{-ix}
|
|
Execute commands from file @var{file} before loading the inferior (but
|
|
after loading gdbinit files).
|
|
@xref{Startup}.
|
|
|
|
@item -init-eval-command @var{command}
|
|
@itemx -iex @var{command}
|
|
@cindex @code{--init-eval-command}
|
|
@cindex @code{-iex}
|
|
Execute a single @value{GDBN} command before loading the inferior (but
|
|
after loading gdbinit files).
|
|
@xref{Startup}.
|
|
|
|
@item -directory @var{directory}
|
|
@itemx -d @var{directory}
|
|
@cindex @code{--directory}
|
|
@cindex @code{-d}
|
|
Add @var{directory} to the path to search for source and script files.
|
|
|
|
@item -r
|
|
@itemx -readnow
|
|
@cindex @code{--readnow}
|
|
@cindex @code{-r}
|
|
Read each symbol file's entire symbol table immediately, rather than
|
|
the default, which is to read it incrementally as it is needed.
|
|
This makes startup slower, but makes future operations faster.
|
|
|
|
@end table
|
|
|
|
@node Mode Options
|
|
@subsection Choosing Modes
|
|
|
|
You can run @value{GDBN} in various alternative modes---for example, in
|
|
batch mode or quiet mode.
|
|
|
|
@table @code
|
|
@anchor{-nx}
|
|
@item -nx
|
|
@itemx -n
|
|
@cindex @code{--nx}
|
|
@cindex @code{-n}
|
|
Do not execute commands found in any initialization files. Normally,
|
|
@value{GDBN} executes the commands in these files after all the command
|
|
options and arguments have been processed. @xref{Command Files,,Command
|
|
Files}.
|
|
|
|
@item -quiet
|
|
@itemx -silent
|
|
@itemx -q
|
|
@cindex @code{--quiet}
|
|
@cindex @code{--silent}
|
|
@cindex @code{-q}
|
|
``Quiet''. Do not print the introductory and copyright messages. These
|
|
messages are also suppressed in batch mode.
|
|
|
|
@item -batch
|
|
@cindex @code{--batch}
|
|
Run in batch mode. Exit with status @code{0} after processing all the
|
|
command files specified with @samp{-x} (and all commands from
|
|
initialization files, if not inhibited with @samp{-n}). Exit with
|
|
nonzero status if an error occurs in executing the @value{GDBN} commands
|
|
in the command files. Batch mode also disables pagination, sets unlimited
|
|
terminal width and height @pxref{Screen Size}, and acts as if @kbd{set confirm
|
|
off} were in effect (@pxref{Messages/Warnings}).
|
|
|
|
Batch mode may be useful for running @value{GDBN} as a filter, for
|
|
example to download and run a program on another computer; in order to
|
|
make this more useful, the message
|
|
|
|
@smallexample
|
|
Program exited normally.
|
|
@end smallexample
|
|
|
|
@noindent
|
|
(which is ordinarily issued whenever a program running under
|
|
@value{GDBN} control terminates) is not issued when running in batch
|
|
mode.
|
|
|
|
@item -batch-silent
|
|
@cindex @code{--batch-silent}
|
|
Run in batch mode exactly like @samp{-batch}, but totally silently. All
|
|
@value{GDBN} output to @code{stdout} is prevented (@code{stderr} is
|
|
unaffected). This is much quieter than @samp{-silent} and would be useless
|
|
for an interactive session.
|
|
|
|
This is particularly useful when using targets that give @samp{Loading section}
|
|
messages, for example.
|
|
|
|
Note that targets that give their output via @value{GDBN}, as opposed to
|
|
writing directly to @code{stdout}, will also be made silent.
|
|
|
|
@item -return-child-result
|
|
@cindex @code{--return-child-result}
|
|
The return code from @value{GDBN} will be the return code from the child
|
|
process (the process being debugged), with the following exceptions:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
@value{GDBN} exits abnormally. E.g., due to an incorrect argument or an
|
|
internal error. In this case the exit code is the same as it would have been
|
|
without @samp{-return-child-result}.
|
|
@item
|
|
The user quits with an explicit value. E.g., @samp{quit 1}.
|
|
@item
|
|
The child process never runs, or is not allowed to terminate, in which case
|
|
the exit code will be -1.
|
|
@end itemize
|
|
|
|
This option is useful in conjunction with @samp{-batch} or @samp{-batch-silent},
|
|
when @value{GDBN} is being used as a remote program loader or simulator
|
|
interface.
|
|
|
|
@item -nowindows
|
|
@itemx -nw
|
|
@cindex @code{--nowindows}
|
|
@cindex @code{-nw}
|
|
``No windows''. If @value{GDBN} comes with a graphical user interface
|
|
(GUI) built in, then this option tells @value{GDBN} to only use the command-line
|
|
interface. If no GUI is available, this option has no effect.
|
|
|
|
@item -windows
|
|
@itemx -w
|
|
@cindex @code{--windows}
|
|
@cindex @code{-w}
|
|
If @value{GDBN} includes a GUI, then this option requires it to be
|
|
used if possible.
|
|
|
|
@item -cd @var{directory}
|
|
@cindex @code{--cd}
|
|
Run @value{GDBN} using @var{directory} as its working directory,
|
|
instead of the current directory.
|
|
|
|
@item -data-directory @var{directory}
|
|
@cindex @code{--data-directory}
|
|
Run @value{GDBN} using @var{directory} as its data directory.
|
|
The data directory is where @value{GDBN} searches for its
|
|
auxiliary files. @xref{Data Files}.
|
|
|
|
@item -fullname
|
|
@itemx -f
|
|
@cindex @code{--fullname}
|
|
@cindex @code{-f}
|
|
@sc{gnu} Emacs sets this option when it runs @value{GDBN} as a
|
|
subprocess. It tells @value{GDBN} to output the full file name and line
|
|
number in a standard, recognizable fashion each time a stack frame is
|
|
displayed (which includes each time your program stops). This
|
|
recognizable format looks like two @samp{\032} characters, followed by
|
|
the file name, line number and character position separated by colons,
|
|
and a newline. The Emacs-to-@value{GDBN} interface program uses the two
|
|
@samp{\032} characters as a signal to display the source code for the
|
|
frame.
|
|
|
|
@item -epoch
|
|
@cindex @code{--epoch}
|
|
The Epoch Emacs-@value{GDBN} interface sets this option when it runs
|
|
@value{GDBN} as a subprocess. It tells @value{GDBN} to modify its print
|
|
routines so as to allow Epoch to display values of expressions in a
|
|
separate window.
|
|
|
|
@item -annotate @var{level}
|
|
@cindex @code{--annotate}
|
|
This option sets the @dfn{annotation level} inside @value{GDBN}. Its
|
|
effect is identical to using @samp{set annotate @var{level}}
|
|
(@pxref{Annotations}). The annotation @var{level} controls how much
|
|
information @value{GDBN} prints together with its prompt, values of
|
|
expressions, source lines, and other types of output. Level 0 is the
|
|
normal, level 1 is for use when @value{GDBN} is run as a subprocess of
|
|
@sc{gnu} Emacs, level 3 is the maximum annotation suitable for programs
|
|
that control @value{GDBN}, and level 2 has been deprecated.
|
|
|
|
The annotation mechanism has largely been superseded by @sc{gdb/mi}
|
|
(@pxref{GDB/MI}).
|
|
|
|
@item --args
|
|
@cindex @code{--args}
|
|
Change interpretation of command line so that arguments following the
|
|
executable file are passed as command line arguments to the inferior.
|
|
This option stops option processing.
|
|
|
|
@item -baud @var{bps}
|
|
@itemx -b @var{bps}
|
|
@cindex @code{--baud}
|
|
@cindex @code{-b}
|
|
Set the line speed (baud rate or bits per second) of any serial
|
|
interface used by @value{GDBN} for remote debugging.
|
|
|
|
@item -l @var{timeout}
|
|
@cindex @code{-l}
|
|
Set the timeout (in seconds) of any communication used by @value{GDBN}
|
|
for remote debugging.
|
|
|
|
@item -tty @var{device}
|
|
@itemx -t @var{device}
|
|
@cindex @code{--tty}
|
|
@cindex @code{-t}
|
|
Run using @var{device} for your program's standard input and output.
|
|
@c FIXME: kingdon thinks there is more to -tty. Investigate.
|
|
|
|
@c resolve the situation of these eventually
|
|
@item -tui
|
|
@cindex @code{--tui}
|
|
Activate the @dfn{Text User Interface} when starting. The Text User
|
|
Interface manages several text windows on the terminal, showing
|
|
source, assembly, registers and @value{GDBN} command outputs
|
|
(@pxref{TUI, ,@value{GDBN} Text User Interface}). Do not use this
|
|
option if you run @value{GDBN} from Emacs (@pxref{Emacs, ,
|
|
Using @value{GDBN} under @sc{gnu} Emacs}).
|
|
|
|
@c @item -xdb
|
|
@c @cindex @code{--xdb}
|
|
@c Run in XDB compatibility mode, allowing the use of certain XDB commands.
|
|
@c For information, see the file @file{xdb_trans.html}, which is usually
|
|
@c installed in the directory @code{/opt/langtools/wdb/doc} on HP-UX
|
|
@c systems.
|
|
|
|
@item -interpreter @var{interp}
|
|
@cindex @code{--interpreter}
|
|
Use the interpreter @var{interp} for interface with the controlling
|
|
program or device. This option is meant to be set by programs which
|
|
communicate with @value{GDBN} using it as a back end.
|
|
@xref{Interpreters, , Command Interpreters}.
|
|
|
|
@samp{--interpreter=mi} (or @samp{--interpreter=mi2}) causes
|
|
@value{GDBN} to use the @dfn{@sc{gdb/mi} interface} (@pxref{GDB/MI, ,
|
|
The @sc{gdb/mi} Interface}) included since @value{GDBN} version 6.0. The
|
|
previous @sc{gdb/mi} interface, included in @value{GDBN} version 5.3 and
|
|
selected with @samp{--interpreter=mi1}, is deprecated. Earlier
|
|
@sc{gdb/mi} interfaces are no longer supported.
|
|
|
|
@item -write
|
|
@cindex @code{--write}
|
|
Open the executable and core files for both reading and writing. This
|
|
is equivalent to the @samp{set write on} command inside @value{GDBN}
|
|
(@pxref{Patching}).
|
|
|
|
@item -statistics
|
|
@cindex @code{--statistics}
|
|
This option causes @value{GDBN} to print statistics about time and
|
|
memory usage after it completes each command and returns to the prompt.
|
|
|
|
@item -version
|
|
@cindex @code{--version}
|
|
This option causes @value{GDBN} to print its version number and
|
|
no-warranty blurb, and exit.
|
|
|
|
@end table
|
|
|
|
@node Startup
|
|
@subsection What @value{GDBN} Does During Startup
|
|
@cindex @value{GDBN} startup
|
|
|
|
Here's the description of what @value{GDBN} does during session startup:
|
|
|
|
@enumerate
|
|
@item
|
|
Sets up the command interpreter as specified by the command line
|
|
(@pxref{Mode Options, interpreter}).
|
|
|
|
@item
|
|
@cindex init file
|
|
Reads the system-wide @dfn{init file} (if @option{--with-system-gdbinit} was
|
|
used when building @value{GDBN}; @pxref{System-wide configuration,
|
|
,System-wide configuration and settings}) and executes all the commands in
|
|
that file.
|
|
|
|
@anchor{Home Directory Init File}
|
|
@item
|
|
Reads the init file (if any) in your home directory@footnote{On
|
|
DOS/Windows systems, the home directory is the one pointed to by the
|
|
@code{HOME} environment variable.} and executes all the commands in
|
|
that file.
|
|
|
|
@anchor{Option -init-eval-command}
|
|
@item
|
|
Executes commands and command files specified by the @samp{-iex} and
|
|
@samp{-ix} options in their specified order. Usually you should use the
|
|
@samp{-ex} and @samp{-x} options instead, but this way you can apply
|
|
settings before @value{GDBN} init files get executed and before inferior
|
|
gets loaded.
|
|
|
|
@item
|
|
Processes command line options and operands.
|
|
|
|
@anchor{Init File in the Current Directory during Startup}
|
|
@item
|
|
Reads and executes the commands from init file (if any) in the current
|
|
working directory as long as @samp{set auto-load local-gdbinit} is set to
|
|
@samp{on} (@pxref{Init File in the Current Directory}).
|
|
This is only done if the current directory is
|
|
different from your home directory. Thus, you can have more than one
|
|
init file, one generic in your home directory, and another, specific
|
|
to the program you are debugging, in the directory where you invoke
|
|
@value{GDBN}.
|
|
|
|
@item
|
|
If the command line specified a program to debug, or a process to
|
|
attach to, or a core file, @value{GDBN} loads any auto-loaded
|
|
scripts provided for the program or for its loaded shared libraries.
|
|
@xref{Auto-loading}.
|
|
|
|
If you wish to disable the auto-loading during startup,
|
|
you must do something like the following:
|
|
|
|
@smallexample
|
|
$ gdb -iex "set auto-load python-scripts off" myprogram
|
|
@end smallexample
|
|
|
|
Option @samp{-ex} does not work because the auto-loading is then turned
|
|
off too late.
|
|
|
|
@item
|
|
Executes commands and command files specified by the @samp{-ex} and
|
|
@samp{-x} options in their specified order. @xref{Command Files}, for
|
|
more details about @value{GDBN} command files.
|
|
|
|
@item
|
|
Reads the command history recorded in the @dfn{history file}.
|
|
@xref{Command History}, for more details about the command history and the
|
|
files where @value{GDBN} records it.
|
|
@end enumerate
|
|
|
|
Init files use the same syntax as @dfn{command files} (@pxref{Command
|
|
Files}) and are processed by @value{GDBN} in the same way. The init
|
|
file in your home directory can set options (such as @samp{set
|
|
complaints}) that affect subsequent processing of command line options
|
|
and operands. Init files are not executed if you use the @samp{-nx}
|
|
option (@pxref{Mode Options, ,Choosing Modes}).
|
|
|
|
To display the list of init files loaded by gdb at startup, you
|
|
can use @kbd{gdb --help}.
|
|
|
|
@cindex init file name
|
|
@cindex @file{.gdbinit}
|
|
@cindex @file{gdb.ini}
|
|
The @value{GDBN} init files are normally called @file{.gdbinit}.
|
|
The DJGPP port of @value{GDBN} uses the name @file{gdb.ini}, due to
|
|
the limitations of file names imposed by DOS filesystems. The Windows
|
|
ports of @value{GDBN} use the standard name, but if they find a
|
|
@file{gdb.ini} file, they warn you about that and suggest to rename
|
|
the file to the standard name.
|
|
|
|
|
|
@node Quitting GDB
|
|
@section Quitting @value{GDBN}
|
|
@cindex exiting @value{GDBN}
|
|
@cindex leaving @value{GDBN}
|
|
|
|
@table @code
|
|
@kindex quit @r{[}@var{expression}@r{]}
|
|
@kindex q @r{(@code{quit})}
|
|
@item quit @r{[}@var{expression}@r{]}
|
|
@itemx q
|
|
To exit @value{GDBN}, use the @code{quit} command (abbreviated
|
|
@code{q}), or type an end-of-file character (usually @kbd{Ctrl-d}). If you
|
|
do not supply @var{expression}, @value{GDBN} will terminate normally;
|
|
otherwise it will terminate using the result of @var{expression} as the
|
|
error code.
|
|
@end table
|
|
|
|
@cindex interrupt
|
|
An interrupt (often @kbd{Ctrl-c}) does not exit from @value{GDBN}, but rather
|
|
terminates the action of any @value{GDBN} command that is in progress and
|
|
returns to @value{GDBN} command level. It is safe to type the interrupt
|
|
character at any time because @value{GDBN} does not allow it to take effect
|
|
until a time when it is safe.
|
|
|
|
If you have been using @value{GDBN} to control an attached process or
|
|
device, you can release it with the @code{detach} command
|
|
(@pxref{Attach, ,Debugging an Already-running Process}).
|
|
|
|
@node Shell Commands
|
|
@section Shell Commands
|
|
|
|
If you need to execute occasional shell commands during your
|
|
debugging session, there is no need to leave or suspend @value{GDBN}; you can
|
|
just use the @code{shell} command.
|
|
|
|
@table @code
|
|
@kindex shell
|
|
@kindex !
|
|
@cindex shell escape
|
|
@item shell @var{command-string}
|
|
@itemx !@var{command-string}
|
|
Invoke a standard shell to execute @var{command-string}.
|
|
Note that no space is needed between @code{!} and @var{command-string}.
|
|
If it exists, the environment variable @code{SHELL} determines which
|
|
shell to run. Otherwise @value{GDBN} uses the default shell
|
|
(@file{/bin/sh} on Unix systems, @file{COMMAND.COM} on MS-DOS, etc.).
|
|
@end table
|
|
|
|
The utility @code{make} is often needed in development environments.
|
|
You do not have to use the @code{shell} command for this purpose in
|
|
@value{GDBN}:
|
|
|
|
@table @code
|
|
@kindex make
|
|
@cindex calling make
|
|
@item make @var{make-args}
|
|
Execute the @code{make} program with the specified
|
|
arguments. This is equivalent to @samp{shell make @var{make-args}}.
|
|
@end table
|
|
|
|
@node Logging Output
|
|
@section Logging Output
|
|
@cindex logging @value{GDBN} output
|
|
@cindex save @value{GDBN} output to a file
|
|
|
|
You may want to save the output of @value{GDBN} commands to a file.
|
|
There are several commands to control @value{GDBN}'s logging.
|
|
|
|
@table @code
|
|
@kindex set logging
|
|
@item set logging on
|
|
Enable logging.
|
|
@item set logging off
|
|
Disable logging.
|
|
@cindex logging file name
|
|
@item set logging file @var{file}
|
|
Change the name of the current logfile. The default logfile is @file{gdb.txt}.
|
|
@item set logging overwrite [on|off]
|
|
By default, @value{GDBN} will append to the logfile. Set @code{overwrite} if
|
|
you want @code{set logging on} to overwrite the logfile instead.
|
|
@item set logging redirect [on|off]
|
|
By default, @value{GDBN} output will go to both the terminal and the logfile.
|
|
Set @code{redirect} if you want output to go only to the log file.
|
|
@kindex show logging
|
|
@item show logging
|
|
Show the current values of the logging settings.
|
|
@end table
|
|
|
|
@node Commands
|
|
@chapter @value{GDBN} Commands
|
|
|
|
You can abbreviate a @value{GDBN} command to the first few letters of the command
|
|
name, if that abbreviation is unambiguous; and you can repeat certain
|
|
@value{GDBN} commands by typing just @key{RET}. You can also use the @key{TAB}
|
|
key to get @value{GDBN} to fill out the rest of a word in a command (or to
|
|
show you the alternatives available, if there is more than one possibility).
|
|
|
|
@menu
|
|
* Command Syntax:: How to give commands to @value{GDBN}
|
|
* Completion:: Command completion
|
|
* Help:: How to ask @value{GDBN} for help
|
|
@end menu
|
|
|
|
@node Command Syntax
|
|
@section Command Syntax
|
|
|
|
A @value{GDBN} command is a single line of input. There is no limit on
|
|
how long it can be. It starts with a command name, which is followed by
|
|
arguments whose meaning depends on the command name. For example, the
|
|
command @code{step} accepts an argument which is the number of times to
|
|
step, as in @samp{step 5}. You can also use the @code{step} command
|
|
with no arguments. Some commands do not allow any arguments.
|
|
|
|
@cindex abbreviation
|
|
@value{GDBN} command names may always be truncated if that abbreviation is
|
|
unambiguous. Other possible command abbreviations are listed in the
|
|
documentation for individual commands. In some cases, even ambiguous
|
|
abbreviations are allowed; for example, @code{s} is specially defined as
|
|
equivalent to @code{step} even though there are other commands whose
|
|
names start with @code{s}. You can test abbreviations by using them as
|
|
arguments to the @code{help} command.
|
|
|
|
@cindex repeating commands
|
|
@kindex RET @r{(repeat last command)}
|
|
A blank line as input to @value{GDBN} (typing just @key{RET}) means to
|
|
repeat the previous command. Certain commands (for example, @code{run})
|
|
will not repeat this way; these are commands whose unintentional
|
|
repetition might cause trouble and which you are unlikely to want to
|
|
repeat. User-defined commands can disable this feature; see
|
|
@ref{Define, dont-repeat}.
|
|
|
|
The @code{list} and @code{x} commands, when you repeat them with
|
|
@key{RET}, construct new arguments rather than repeating
|
|
exactly as typed. This permits easy scanning of source or memory.
|
|
|
|
@value{GDBN} can also use @key{RET} in another way: to partition lengthy
|
|
output, in a way similar to the common utility @code{more}
|
|
(@pxref{Screen Size,,Screen Size}). Since it is easy to press one
|
|
@key{RET} too many in this situation, @value{GDBN} disables command
|
|
repetition after any command that generates this sort of display.
|
|
|
|
@kindex # @r{(a comment)}
|
|
@cindex comment
|
|
Any text from a @kbd{#} to the end of the line is a comment; it does
|
|
nothing. This is useful mainly in command files (@pxref{Command
|
|
Files,,Command Files}).
|
|
|
|
@cindex repeating command sequences
|
|
@kindex Ctrl-o @r{(operate-and-get-next)}
|
|
The @kbd{Ctrl-o} binding is useful for repeating a complex sequence of
|
|
commands. This command accepts the current line, like @key{RET}, and
|
|
then fetches the next line relative to the current line from the history
|
|
for editing.
|
|
|
|
@node Completion
|
|
@section Command Completion
|
|
|
|
@cindex completion
|
|
@cindex word completion
|
|
@value{GDBN} can fill in the rest of a word in a command for you, if there is
|
|
only one possibility; it can also show you what the valid possibilities
|
|
are for the next word in a command, at any time. This works for @value{GDBN}
|
|
commands, @value{GDBN} subcommands, and the names of symbols in your program.
|
|
|
|
Press the @key{TAB} key whenever you want @value{GDBN} to fill out the rest
|
|
of a word. If there is only one possibility, @value{GDBN} fills in the
|
|
word, and waits for you to finish the command (or press @key{RET} to
|
|
enter it). For example, if you type
|
|
|
|
@c FIXME "@key" does not distinguish its argument sufficiently to permit
|
|
@c complete accuracy in these examples; space introduced for clarity.
|
|
@c If texinfo enhancements make it unnecessary, it would be nice to
|
|
@c replace " @key" by "@key" in the following...
|
|
@smallexample
|
|
(@value{GDBP}) info bre @key{TAB}
|
|
@end smallexample
|
|
|
|
@noindent
|
|
@value{GDBN} fills in the rest of the word @samp{breakpoints}, since that is
|
|
the only @code{info} subcommand beginning with @samp{bre}:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) info breakpoints
|
|
@end smallexample
|
|
|
|
@noindent
|
|
You can either press @key{RET} at this point, to run the @code{info
|
|
breakpoints} command, or backspace and enter something else, if
|
|
@samp{breakpoints} does not look like the command you expected. (If you
|
|
were sure you wanted @code{info breakpoints} in the first place, you
|
|
might as well just type @key{RET} immediately after @samp{info bre},
|
|
to exploit command abbreviations rather than command completion).
|
|
|
|
If there is more than one possibility for the next word when you press
|
|
@key{TAB}, @value{GDBN} sounds a bell. You can either supply more
|
|
characters and try again, or just press @key{TAB} a second time;
|
|
@value{GDBN} displays all the possible completions for that word. For
|
|
example, you might want to set a breakpoint on a subroutine whose name
|
|
begins with @samp{make_}, but when you type @kbd{b make_@key{TAB}} @value{GDBN}
|
|
just sounds the bell. Typing @key{TAB} again displays all the
|
|
function names in your program that begin with those characters, for
|
|
example:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) b make_ @key{TAB}
|
|
@exdent @value{GDBN} sounds bell; press @key{TAB} again, to see:
|
|
make_a_section_from_file make_environ
|
|
make_abs_section make_function_type
|
|
make_blockvector make_pointer_type
|
|
make_cleanup make_reference_type
|
|
make_command make_symbol_completion_list
|
|
(@value{GDBP}) b make_
|
|
@end smallexample
|
|
|
|
@noindent
|
|
After displaying the available possibilities, @value{GDBN} copies your
|
|
partial input (@samp{b make_} in the example) so you can finish the
|
|
command.
|
|
|
|
If you just want to see the list of alternatives in the first place, you
|
|
can press @kbd{M-?} rather than pressing @key{TAB} twice. @kbd{M-?}
|
|
means @kbd{@key{META} ?}. You can type this either by holding down a
|
|
key designated as the @key{META} shift on your keyboard (if there is
|
|
one) while typing @kbd{?}, or as @key{ESC} followed by @kbd{?}.
|
|
|
|
@cindex quotes in commands
|
|
@cindex completion of quoted strings
|
|
Sometimes the string you need, while logically a ``word'', may contain
|
|
parentheses or other characters that @value{GDBN} normally excludes from
|
|
its notion of a word. To permit word completion to work in this
|
|
situation, you may enclose words in @code{'} (single quote marks) in
|
|
@value{GDBN} commands.
|
|
|
|
The most likely situation where you might need this is in typing the
|
|
name of a C@t{++} function. This is because C@t{++} allows function
|
|
overloading (multiple definitions of the same function, distinguished
|
|
by argument type). For example, when you want to set a breakpoint you
|
|
may need to distinguish whether you mean the version of @code{name}
|
|
that takes an @code{int} parameter, @code{name(int)}, or the version
|
|
that takes a @code{float} parameter, @code{name(float)}. To use the
|
|
word-completion facilities in this situation, type a single quote
|
|
@code{'} at the beginning of the function name. This alerts
|
|
@value{GDBN} that it may need to consider more information than usual
|
|
when you press @key{TAB} or @kbd{M-?} to request word completion:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) b 'bubble( @kbd{M-?}
|
|
bubble(double,double) bubble(int,int)
|
|
(@value{GDBP}) b 'bubble(
|
|
@end smallexample
|
|
|
|
In some cases, @value{GDBN} can tell that completing a name requires using
|
|
quotes. When this happens, @value{GDBN} inserts the quote for you (while
|
|
completing as much as it can) if you do not type the quote in the first
|
|
place:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) b bub @key{TAB}
|
|
@exdent @value{GDBN} alters your input line to the following, and rings a bell:
|
|
(@value{GDBP}) b 'bubble(
|
|
@end smallexample
|
|
|
|
@noindent
|
|
In general, @value{GDBN} can tell that a quote is needed (and inserts it) if
|
|
you have not yet started typing the argument list when you ask for
|
|
completion on an overloaded symbol.
|
|
|
|
For more information about overloaded functions, see @ref{C Plus Plus
|
|
Expressions, ,C@t{++} Expressions}. You can use the command @code{set
|
|
overload-resolution off} to disable overload resolution;
|
|
see @ref{Debugging C Plus Plus, ,@value{GDBN} Features for C@t{++}}.
|
|
|
|
@cindex completion of structure field names
|
|
@cindex structure field name completion
|
|
@cindex completion of union field names
|
|
@cindex union field name completion
|
|
When completing in an expression which looks up a field in a
|
|
structure, @value{GDBN} also tries@footnote{The completer can be
|
|
confused by certain kinds of invalid expressions. Also, it only
|
|
examines the static type of the expression, not the dynamic type.} to
|
|
limit completions to the field names available in the type of the
|
|
left-hand-side:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) p gdb_stdout.@kbd{M-?}
|
|
magic to_fputs to_rewind
|
|
to_data to_isatty to_write
|
|
to_delete to_put to_write_async_safe
|
|
to_flush to_read
|
|
@end smallexample
|
|
|
|
@noindent
|
|
This is because the @code{gdb_stdout} is a variable of the type
|
|
@code{struct ui_file} that is defined in @value{GDBN} sources as
|
|
follows:
|
|
|
|
@smallexample
|
|
struct ui_file
|
|
@{
|
|
int *magic;
|
|
ui_file_flush_ftype *to_flush;
|
|
ui_file_write_ftype *to_write;
|
|
ui_file_write_async_safe_ftype *to_write_async_safe;
|
|
ui_file_fputs_ftype *to_fputs;
|
|
ui_file_read_ftype *to_read;
|
|
ui_file_delete_ftype *to_delete;
|
|
ui_file_isatty_ftype *to_isatty;
|
|
ui_file_rewind_ftype *to_rewind;
|
|
ui_file_put_ftype *to_put;
|
|
void *to_data;
|
|
@}
|
|
@end smallexample
|
|
|
|
|
|
@node Help
|
|
@section Getting Help
|
|
@cindex online documentation
|
|
@kindex help
|
|
|
|
You can always ask @value{GDBN} itself for information on its commands,
|
|
using the command @code{help}.
|
|
|
|
@table @code
|
|
@kindex h @r{(@code{help})}
|
|
@item help
|
|
@itemx h
|
|
You can use @code{help} (abbreviated @code{h}) with no arguments to
|
|
display a short list of named classes of commands:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) help
|
|
List of classes of commands:
|
|
|
|
aliases -- Aliases of other commands
|
|
breakpoints -- Making program stop at certain points
|
|
data -- Examining data
|
|
files -- Specifying and examining files
|
|
internals -- Maintenance commands
|
|
obscure -- Obscure features
|
|
running -- Running the program
|
|
stack -- Examining the stack
|
|
status -- Status inquiries
|
|
support -- Support facilities
|
|
tracepoints -- Tracing of program execution without
|
|
stopping the program
|
|
user-defined -- User-defined commands
|
|
|
|
Type "help" followed by a class name for a list of
|
|
commands in that class.
|
|
Type "help" followed by command name for full
|
|
documentation.
|
|
Command name abbreviations are allowed if unambiguous.
|
|
(@value{GDBP})
|
|
@end smallexample
|
|
@c the above line break eliminates huge line overfull...
|
|
|
|
@item help @var{class}
|
|
Using one of the general help classes as an argument, you can get a
|
|
list of the individual commands in that class. For example, here is the
|
|
help display for the class @code{status}:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) help status
|
|
Status inquiries.
|
|
|
|
List of commands:
|
|
|
|
@c Line break in "show" line falsifies real output, but needed
|
|
@c to fit in smallbook page size.
|
|
info -- Generic command for showing things
|
|
about the program being debugged
|
|
show -- Generic command for showing things
|
|
about the debugger
|
|
|
|
Type "help" followed by command name for full
|
|
documentation.
|
|
Command name abbreviations are allowed if unambiguous.
|
|
(@value{GDBP})
|
|
@end smallexample
|
|
|
|
@item help @var{command}
|
|
With a command name as @code{help} argument, @value{GDBN} displays a
|
|
short paragraph on how to use that command.
|
|
|
|
@kindex apropos
|
|
@item apropos @var{args}
|
|
The @code{apropos} command searches through all of the @value{GDBN}
|
|
commands, and their documentation, for the regular expression specified in
|
|
@var{args}. It prints out all matches found. For example:
|
|
|
|
@smallexample
|
|
apropos alias
|
|
@end smallexample
|
|
|
|
@noindent
|
|
results in:
|
|
|
|
@smallexample
|
|
@c @group
|
|
alias -- Define a new command that is an alias of an existing command
|
|
aliases -- Aliases of other commands
|
|
d -- Delete some breakpoints or auto-display expressions
|
|
del -- Delete some breakpoints or auto-display expressions
|
|
delete -- Delete some breakpoints or auto-display expressions
|
|
@c @end group
|
|
@end smallexample
|
|
|
|
@kindex complete
|
|
@item complete @var{args}
|
|
The @code{complete @var{args}} command lists all the possible completions
|
|
for the beginning of a command. Use @var{args} to specify the beginning of the
|
|
command you want completed. For example:
|
|
|
|
@smallexample
|
|
complete i
|
|
@end smallexample
|
|
|
|
@noindent results in:
|
|
|
|
@smallexample
|
|
@group
|
|
if
|
|
ignore
|
|
info
|
|
inspect
|
|
@end group
|
|
@end smallexample
|
|
|
|
@noindent This is intended for use by @sc{gnu} Emacs.
|
|
@end table
|
|
|
|
In addition to @code{help}, you can use the @value{GDBN} commands @code{info}
|
|
and @code{show} to inquire about the state of your program, or the state
|
|
of @value{GDBN} itself. Each command supports many topics of inquiry; this
|
|
manual introduces each of them in the appropriate context. The listings
|
|
under @code{info} and under @code{show} in the Command, Variable, and
|
|
Function Index point to all the sub-commands. @xref{Command and Variable
|
|
Index}.
|
|
|
|
@c @group
|
|
@table @code
|
|
@kindex info
|
|
@kindex i @r{(@code{info})}
|
|
@item info
|
|
This command (abbreviated @code{i}) is for describing the state of your
|
|
program. For example, you can show the arguments passed to a function
|
|
with @code{info args}, list the registers currently in use with @code{info
|
|
registers}, or list the breakpoints you have set with @code{info breakpoints}.
|
|
You can get a complete list of the @code{info} sub-commands with
|
|
@w{@code{help info}}.
|
|
|
|
@kindex set
|
|
@item set
|
|
You can assign the result of an expression to an environment variable with
|
|
@code{set}. For example, you can set the @value{GDBN} prompt to a $-sign with
|
|
@code{set prompt $}.
|
|
|
|
@kindex show
|
|
@item show
|
|
In contrast to @code{info}, @code{show} is for describing the state of
|
|
@value{GDBN} itself.
|
|
You can change most of the things you can @code{show}, by using the
|
|
related command @code{set}; for example, you can control what number
|
|
system is used for displays with @code{set radix}, or simply inquire
|
|
which is currently in use with @code{show radix}.
|
|
|
|
@kindex info set
|
|
To display all the settable parameters and their current
|
|
values, you can use @code{show} with no arguments; you may also use
|
|
@code{info set}. Both commands produce the same display.
|
|
@c FIXME: "info set" violates the rule that "info" is for state of
|
|
@c FIXME...program. Ck w/ GNU: "info set" to be called something else,
|
|
@c FIXME...or change desc of rule---eg "state of prog and debugging session"?
|
|
@end table
|
|
@c @end group
|
|
|
|
Here are three miscellaneous @code{show} subcommands, all of which are
|
|
exceptional in lacking corresponding @code{set} commands:
|
|
|
|
@table @code
|
|
@kindex show version
|
|
@cindex @value{GDBN} version number
|
|
@item show version
|
|
Show what version of @value{GDBN} is running. You should include this
|
|
information in @value{GDBN} bug-reports. If multiple versions of
|
|
@value{GDBN} are in use at your site, you may need to determine which
|
|
version of @value{GDBN} you are running; as @value{GDBN} evolves, new
|
|
commands are introduced, and old ones may wither away. Also, many
|
|
system vendors ship variant versions of @value{GDBN}, and there are
|
|
variant versions of @value{GDBN} in @sc{gnu}/Linux distributions as well.
|
|
The version number is the same as the one announced when you start
|
|
@value{GDBN}.
|
|
|
|
@kindex show copying
|
|
@kindex info copying
|
|
@cindex display @value{GDBN} copyright
|
|
@item show copying
|
|
@itemx info copying
|
|
Display information about permission for copying @value{GDBN}.
|
|
|
|
@kindex show warranty
|
|
@kindex info warranty
|
|
@item show warranty
|
|
@itemx info warranty
|
|
Display the @sc{gnu} ``NO WARRANTY'' statement, or a warranty,
|
|
if your version of @value{GDBN} comes with one.
|
|
|
|
@end table
|
|
|
|
@node Running
|
|
@chapter Running Programs Under @value{GDBN}
|
|
|
|
When you run a program under @value{GDBN}, you must first generate
|
|
debugging information when you compile it.
|
|
|
|
You may start @value{GDBN} with its arguments, if any, in an environment
|
|
of your choice. If you are doing native debugging, you may redirect
|
|
your program's input and output, debug an already running process, or
|
|
kill a child process.
|
|
|
|
@menu
|
|
* Compilation:: Compiling for debugging
|
|
* Starting:: Starting your program
|
|
* Arguments:: Your program's arguments
|
|
* Environment:: Your program's environment
|
|
|
|
* Working Directory:: Your program's working directory
|
|
* Input/Output:: Your program's input and output
|
|
* Attach:: Debugging an already-running process
|
|
* Kill Process:: Killing the child process
|
|
|
|
* Inferiors and Programs:: Debugging multiple inferiors and programs
|
|
* Threads:: Debugging programs with multiple threads
|
|
* Forks:: Debugging forks
|
|
* Checkpoint/Restart:: Setting a @emph{bookmark} to return to later
|
|
@end menu
|
|
|
|
@node Compilation
|
|
@section Compiling for Debugging
|
|
|
|
In order to debug a program effectively, you need to generate
|
|
debugging information when you compile it. This debugging information
|
|
is stored in the object file; it describes the data type of each
|
|
variable or function and the correspondence between source line numbers
|
|
and addresses in the executable code.
|
|
|
|
To request debugging information, specify the @samp{-g} option when you run
|
|
the compiler.
|
|
|
|
Programs that are to be shipped to your customers are compiled with
|
|
optimizations, using the @samp{-O} compiler option. However, some
|
|
compilers are unable to handle the @samp{-g} and @samp{-O} options
|
|
together. Using those compilers, you cannot generate optimized
|
|
executables containing debugging information.
|
|
|
|
@value{NGCC}, the @sc{gnu} C/C@t{++} compiler, supports @samp{-g} with or
|
|
without @samp{-O}, making it possible to debug optimized code. We
|
|
recommend that you @emph{always} use @samp{-g} whenever you compile a
|
|
program. You may think your program is correct, but there is no sense
|
|
in pushing your luck. For more information, see @ref{Optimized Code}.
|
|
|
|
Older versions of the @sc{gnu} C compiler permitted a variant option
|
|
@w{@samp{-gg}} for debugging information. @value{GDBN} no longer supports this
|
|
format; if your @sc{gnu} C compiler has this option, do not use it.
|
|
|
|
@value{GDBN} knows about preprocessor macros and can show you their
|
|
expansion (@pxref{Macros}). Most compilers do not include information
|
|
about preprocessor macros in the debugging information if you specify
|
|
the @option{-g} flag alone. Version 3.1 and later of @value{NGCC},
|
|
the @sc{gnu} C compiler, provides macro information if you are using
|
|
the DWARF debugging format, and specify the option @option{-g3}.
|
|
|
|
@xref{Debugging Options,,Options for Debugging Your Program or GCC,
|
|
gcc.info, Using the @sc{gnu} Compiler Collection (GCC)}, for more
|
|
information on @value{NGCC} options affecting debug information.
|
|
|
|
You will have the best debugging experience if you use the latest
|
|
version of the DWARF debugging format that your compiler supports.
|
|
DWARF is currently the most expressive and best supported debugging
|
|
format in @value{GDBN}.
|
|
|
|
@need 2000
|
|
@node Starting
|
|
@section Starting your Program
|
|
@cindex starting
|
|
@cindex running
|
|
|
|
@table @code
|
|
@kindex run
|
|
@kindex r @r{(@code{run})}
|
|
@item run
|
|
@itemx r
|
|
Use the @code{run} command to start your program under @value{GDBN}.
|
|
You must first specify the program name (except on VxWorks) with an
|
|
argument to @value{GDBN} (@pxref{Invocation, ,Getting In and Out of
|
|
@value{GDBN}}), or by using the @code{file} or @code{exec-file} command
|
|
(@pxref{Files, ,Commands to Specify Files}).
|
|
|
|
@end table
|
|
|
|
If you are running your program in an execution environment that
|
|
supports processes, @code{run} creates an inferior process and makes
|
|
that process run your program. In some environments without processes,
|
|
@code{run} jumps to the start of your program. Other targets,
|
|
like @samp{remote}, are always running. If you get an error
|
|
message like this one:
|
|
|
|
@smallexample
|
|
The "remote" target does not support "run".
|
|
Try "help target" or "continue".
|
|
@end smallexample
|
|
|
|
@noindent
|
|
then use @code{continue} to run your program. You may need @code{load}
|
|
first (@pxref{load}).
|
|
|
|
The execution of a program is affected by certain information it
|
|
receives from its superior. @value{GDBN} provides ways to specify this
|
|
information, which you must do @emph{before} starting your program. (You
|
|
can change it after starting your program, but such changes only affect
|
|
your program the next time you start it.) This information may be
|
|
divided into four categories:
|
|
|
|
@table @asis
|
|
@item The @emph{arguments.}
|
|
Specify the arguments to give your program as the arguments of the
|
|
@code{run} command. If a shell is available on your target, the shell
|
|
is used to pass the arguments, so that you may use normal conventions
|
|
(such as wildcard expansion or variable substitution) in describing
|
|
the arguments.
|
|
In Unix systems, you can control which shell is used with the
|
|
@code{SHELL} environment variable.
|
|
@xref{Arguments, ,Your Program's Arguments}.
|
|
|
|
@item The @emph{environment.}
|
|
Your program normally inherits its environment from @value{GDBN}, but you can
|
|
use the @value{GDBN} commands @code{set environment} and @code{unset
|
|
environment} to change parts of the environment that affect
|
|
your program. @xref{Environment, ,Your Program's Environment}.
|
|
|
|
@item The @emph{working directory.}
|
|
Your program inherits its working directory from @value{GDBN}. You can set
|
|
the @value{GDBN} working directory with the @code{cd} command in @value{GDBN}.
|
|
@xref{Working Directory, ,Your Program's Working Directory}.
|
|
|
|
@item The @emph{standard input and output.}
|
|
Your program normally uses the same device for standard input and
|
|
standard output as @value{GDBN} is using. You can redirect input and output
|
|
in the @code{run} command line, or you can use the @code{tty} command to
|
|
set a different device for your program.
|
|
@xref{Input/Output, ,Your Program's Input and Output}.
|
|
|
|
@cindex pipes
|
|
@emph{Warning:} While input and output redirection work, you cannot use
|
|
pipes to pass the output of the program you are debugging to another
|
|
program; if you attempt this, @value{GDBN} is likely to wind up debugging the
|
|
wrong program.
|
|
@end table
|
|
|
|
When you issue the @code{run} command, your program begins to execute
|
|
immediately. @xref{Stopping, ,Stopping and Continuing}, for discussion
|
|
of how to arrange for your program to stop. Once your program has
|
|
stopped, you may call functions in your program, using the @code{print}
|
|
or @code{call} commands. @xref{Data, ,Examining Data}.
|
|
|
|
If the modification time of your symbol file has changed since the last
|
|
time @value{GDBN} read its symbols, @value{GDBN} discards its symbol
|
|
table, and reads it again. When it does this, @value{GDBN} tries to retain
|
|
your current breakpoints.
|
|
|
|
@table @code
|
|
@kindex start
|
|
@item start
|
|
@cindex run to main procedure
|
|
The name of the main procedure can vary from language to language.
|
|
With C or C@t{++}, the main procedure name is always @code{main}, but
|
|
other languages such as Ada do not require a specific name for their
|
|
main procedure. The debugger provides a convenient way to start the
|
|
execution of the program and to stop at the beginning of the main
|
|
procedure, depending on the language used.
|
|
|
|
The @samp{start} command does the equivalent of setting a temporary
|
|
breakpoint at the beginning of the main procedure and then invoking
|
|
the @samp{run} command.
|
|
|
|
@cindex elaboration phase
|
|
Some programs contain an @dfn{elaboration} phase where some startup code is
|
|
executed before the main procedure is called. This depends on the
|
|
languages used to write your program. In C@t{++}, for instance,
|
|
constructors for static and global objects are executed before
|
|
@code{main} is called. It is therefore possible that the debugger stops
|
|
before reaching the main procedure. However, the temporary breakpoint
|
|
will remain to halt execution.
|
|
|
|
Specify the arguments to give to your program as arguments to the
|
|
@samp{start} command. These arguments will be given verbatim to the
|
|
underlying @samp{run} command. Note that the same arguments will be
|
|
reused if no argument is provided during subsequent calls to
|
|
@samp{start} or @samp{run}.
|
|
|
|
It is sometimes necessary to debug the program during elaboration. In
|
|
these cases, using the @code{start} command would stop the execution of
|
|
your program too late, as the program would have already completed the
|
|
elaboration phase. Under these circumstances, insert breakpoints in your
|
|
elaboration code before running your program.
|
|
|
|
@kindex set exec-wrapper
|
|
@item set exec-wrapper @var{wrapper}
|
|
@itemx show exec-wrapper
|
|
@itemx unset exec-wrapper
|
|
When @samp{exec-wrapper} is set, the specified wrapper is used to
|
|
launch programs for debugging. @value{GDBN} starts your program
|
|
with a shell command of the form @kbd{exec @var{wrapper}
|
|
@var{program}}. Quoting is added to @var{program} and its
|
|
arguments, but not to @var{wrapper}, so you should add quotes if
|
|
appropriate for your shell. The wrapper runs until it executes
|
|
your program, and then @value{GDBN} takes control.
|
|
|
|
You can use any program that eventually calls @code{execve} with
|
|
its arguments as a wrapper. Several standard Unix utilities do
|
|
this, e.g.@: @code{env} and @code{nohup}. Any Unix shell script ending
|
|
with @code{exec "$@@"} will also work.
|
|
|
|
For example, you can use @code{env} to pass an environment variable to
|
|
the debugged program, without setting the variable in your shell's
|
|
environment:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) set exec-wrapper env 'LD_PRELOAD=libtest.so'
|
|
(@value{GDBP}) run
|
|
@end smallexample
|
|
|
|
This command is available when debugging locally on most targets, excluding
|
|
@sc{djgpp}, Cygwin, MS Windows, and QNX Neutrino.
|
|
|
|
@kindex set disable-randomization
|
|
@item set disable-randomization
|
|
@itemx set disable-randomization on
|
|
This option (enabled by default in @value{GDBN}) will turn off the native
|
|
randomization of the virtual address space of the started program. This option
|
|
is useful for multiple debugging sessions to make the execution better
|
|
reproducible and memory addresses reusable across debugging sessions.
|
|
|
|
This feature is implemented only on certain targets, including @sc{gnu}/Linux.
|
|
On @sc{gnu}/Linux you can get the same behavior using
|
|
|
|
@smallexample
|
|
(@value{GDBP}) set exec-wrapper setarch `uname -m` -R
|
|
@end smallexample
|
|
|
|
@item set disable-randomization off
|
|
Leave the behavior of the started executable unchanged. Some bugs rear their
|
|
ugly heads only when the program is loaded at certain addresses. If your bug
|
|
disappears when you run the program under @value{GDBN}, that might be because
|
|
@value{GDBN} by default disables the address randomization on platforms, such
|
|
as @sc{gnu}/Linux, which do that for stand-alone programs. Use @kbd{set
|
|
disable-randomization off} to try to reproduce such elusive bugs.
|
|
|
|
On targets where it is available, virtual address space randomization
|
|
protects the programs against certain kinds of security attacks. In these
|
|
cases the attacker needs to know the exact location of a concrete executable
|
|
code. Randomizing its location makes it impossible to inject jumps misusing
|
|
a code at its expected addresses.
|
|
|
|
Prelinking shared libraries provides a startup performance advantage but it
|
|
makes addresses in these libraries predictable for privileged processes by
|
|
having just unprivileged access at the target system. Reading the shared
|
|
library binary gives enough information for assembling the malicious code
|
|
misusing it. Still even a prelinked shared library can get loaded at a new
|
|
random address just requiring the regular relocation process during the
|
|
startup. Shared libraries not already prelinked are always loaded at
|
|
a randomly chosen address.
|
|
|
|
Position independent executables (PIE) contain position independent code
|
|
similar to the shared libraries and therefore such executables get loaded at
|
|
a randomly chosen address upon startup. PIE executables always load even
|
|
already prelinked shared libraries at a random address. You can build such
|
|
executable using @command{gcc -fPIE -pie}.
|
|
|
|
Heap (malloc storage), stack and custom mmap areas are always placed randomly
|
|
(as long as the randomization is enabled).
|
|
|
|
@item show disable-randomization
|
|
Show the current setting of the explicit disable of the native randomization of
|
|
the virtual address space of the started program.
|
|
|
|
@end table
|
|
|
|
@node Arguments
|
|
@section Your Program's Arguments
|
|
|
|
@cindex arguments (to your program)
|
|
The arguments to your program can be specified by the arguments of the
|
|
@code{run} command.
|
|
They are passed to a shell, which expands wildcard characters and
|
|
performs redirection of I/O, and thence to your program. Your
|
|
@code{SHELL} environment variable (if it exists) specifies what shell
|
|
@value{GDBN} uses. If you do not define @code{SHELL}, @value{GDBN} uses
|
|
the default shell (@file{/bin/sh} on Unix).
|
|
|
|
On non-Unix systems, the program is usually invoked directly by
|
|
@value{GDBN}, which emulates I/O redirection via the appropriate system
|
|
calls, and the wildcard characters are expanded by the startup code of
|
|
the program, not by the shell.
|
|
|
|
@code{run} with no arguments uses the same arguments used by the previous
|
|
@code{run}, or those set by the @code{set args} command.
|
|
|
|
@table @code
|
|
@kindex set args
|
|
@item set args
|
|
Specify the arguments to be used the next time your program is run. If
|
|
@code{set args} has no arguments, @code{run} executes your program
|
|
with no arguments. Once you have run your program with arguments,
|
|
using @code{set args} before the next @code{run} is the only way to run
|
|
it again without arguments.
|
|
|
|
@kindex show args
|
|
@item show args
|
|
Show the arguments to give your program when it is started.
|
|
@end table
|
|
|
|
@node Environment
|
|
@section Your Program's Environment
|
|
|
|
@cindex environment (of your program)
|
|
The @dfn{environment} consists of a set of environment variables and
|
|
their values. Environment variables conventionally record such things as
|
|
your user name, your home directory, your terminal type, and your search
|
|
path for programs to run. Usually you set up environment variables with
|
|
the shell and they are inherited by all the other programs you run. When
|
|
debugging, it can be useful to try running your program with a modified
|
|
environment without having to start @value{GDBN} over again.
|
|
|
|
@table @code
|
|
@kindex path
|
|
@item path @var{directory}
|
|
Add @var{directory} to the front of the @code{PATH} environment variable
|
|
(the search path for executables) that will be passed to your program.
|
|
The value of @code{PATH} used by @value{GDBN} does not change.
|
|
You may specify several directory names, separated by whitespace or by a
|
|
system-dependent separator character (@samp{:} on Unix, @samp{;} on
|
|
MS-DOS and MS-Windows). If @var{directory} is already in the path, it
|
|
is moved to the front, so it is searched sooner.
|
|
|
|
You can use the string @samp{$cwd} to refer to whatever is the current
|
|
working directory at the time @value{GDBN} searches the path. If you
|
|
use @samp{.} instead, it refers to the directory where you executed the
|
|
@code{path} command. @value{GDBN} replaces @samp{.} in the
|
|
@var{directory} argument (with the current path) before adding
|
|
@var{directory} to the search path.
|
|
@c 'path' is explicitly nonrepeatable, but RMS points out it is silly to
|
|
@c document that, since repeating it would be a no-op.
|
|
|
|
@kindex show paths
|
|
@item show paths
|
|
Display the list of search paths for executables (the @code{PATH}
|
|
environment variable).
|
|
|
|
@kindex show environment
|
|
@item show environment @r{[}@var{varname}@r{]}
|
|
Print the value of environment variable @var{varname} to be given to
|
|
your program when it starts. If you do not supply @var{varname},
|
|
print the names and values of all environment variables to be given to
|
|
your program. You can abbreviate @code{environment} as @code{env}.
|
|
|
|
@kindex set environment
|
|
@item set environment @var{varname} @r{[}=@var{value}@r{]}
|
|
Set environment variable @var{varname} to @var{value}. The value
|
|
changes for your program only, not for @value{GDBN} itself. @var{value} may
|
|
be any string; the values of environment variables are just strings, and
|
|
any interpretation is supplied by your program itself. The @var{value}
|
|
parameter is optional; if it is eliminated, the variable is set to a
|
|
null value.
|
|
@c "any string" here does not include leading, trailing
|
|
@c blanks. Gnu asks: does anyone care?
|
|
|
|
For example, this command:
|
|
|
|
@smallexample
|
|
set env USER = foo
|
|
@end smallexample
|
|
|
|
@noindent
|
|
tells the debugged program, when subsequently run, that its user is named
|
|
@samp{foo}. (The spaces around @samp{=} are used for clarity here; they
|
|
are not actually required.)
|
|
|
|
@kindex unset environment
|
|
@item unset environment @var{varname}
|
|
Remove variable @var{varname} from the environment to be passed to your
|
|
program. This is different from @samp{set env @var{varname} =};
|
|
@code{unset environment} removes the variable from the environment,
|
|
rather than assigning it an empty value.
|
|
@end table
|
|
|
|
@emph{Warning:} On Unix systems, @value{GDBN} runs your program using
|
|
the shell indicated
|
|
by your @code{SHELL} environment variable if it exists (or
|
|
@code{/bin/sh} if not). If your @code{SHELL} variable names a shell
|
|
that runs an initialization file---such as @file{.cshrc} for C-shell, or
|
|
@file{.bashrc} for BASH---any variables you set in that file affect
|
|
your program. You may wish to move setting of environment variables to
|
|
files that are only run when you sign on, such as @file{.login} or
|
|
@file{.profile}.
|
|
|
|
@node Working Directory
|
|
@section Your Program's Working Directory
|
|
|
|
@cindex working directory (of your program)
|
|
Each time you start your program with @code{run}, it inherits its
|
|
working directory from the current working directory of @value{GDBN}.
|
|
The @value{GDBN} working directory is initially whatever it inherited
|
|
from its parent process (typically the shell), but you can specify a new
|
|
working directory in @value{GDBN} with the @code{cd} command.
|
|
|
|
The @value{GDBN} working directory also serves as a default for the commands
|
|
that specify files for @value{GDBN} to operate on. @xref{Files, ,Commands to
|
|
Specify Files}.
|
|
|
|
@table @code
|
|
@kindex cd
|
|
@cindex change working directory
|
|
@item cd @r{[}@var{directory}@r{]}
|
|
Set the @value{GDBN} working directory to @var{directory}. If not
|
|
given, @var{directory} uses @file{'~'}.
|
|
|
|
@kindex pwd
|
|
@item pwd
|
|
Print the @value{GDBN} working directory.
|
|
@end table
|
|
|
|
It is generally impossible to find the current working directory of
|
|
the process being debugged (since a program can change its directory
|
|
during its run). If you work on a system where @value{GDBN} is
|
|
configured with the @file{/proc} support, you can use the @code{info
|
|
proc} command (@pxref{SVR4 Process Information}) to find out the
|
|
current working directory of the debuggee.
|
|
|
|
@node Input/Output
|
|
@section Your Program's Input and Output
|
|
|
|
@cindex redirection
|
|
@cindex i/o
|
|
@cindex terminal
|
|
By default, the program you run under @value{GDBN} does input and output to
|
|
the same terminal that @value{GDBN} uses. @value{GDBN} switches the terminal
|
|
to its own terminal modes to interact with you, but it records the terminal
|
|
modes your program was using and switches back to them when you continue
|
|
running your program.
|
|
|
|
@table @code
|
|
@kindex info terminal
|
|
@item info terminal
|
|
Displays information recorded by @value{GDBN} about the terminal modes your
|
|
program is using.
|
|
@end table
|
|
|
|
You can redirect your program's input and/or output using shell
|
|
redirection with the @code{run} command. For example,
|
|
|
|
@smallexample
|
|
run > outfile
|
|
@end smallexample
|
|
|
|
@noindent
|
|
starts your program, diverting its output to the file @file{outfile}.
|
|
|
|
@kindex tty
|
|
@cindex controlling terminal
|
|
Another way to specify where your program should do input and output is
|
|
with the @code{tty} command. This command accepts a file name as
|
|
argument, and causes this file to be the default for future @code{run}
|
|
commands. It also resets the controlling terminal for the child
|
|
process, for future @code{run} commands. For example,
|
|
|
|
@smallexample
|
|
tty /dev/ttyb
|
|
@end smallexample
|
|
|
|
@noindent
|
|
directs that processes started with subsequent @code{run} commands
|
|
default to do input and output on the terminal @file{/dev/ttyb} and have
|
|
that as their controlling terminal.
|
|
|
|
An explicit redirection in @code{run} overrides the @code{tty} command's
|
|
effect on the input/output device, but not its effect on the controlling
|
|
terminal.
|
|
|
|
When you use the @code{tty} command or redirect input in the @code{run}
|
|
command, only the input @emph{for your program} is affected. The input
|
|
for @value{GDBN} still comes from your terminal. @code{tty} is an alias
|
|
for @code{set inferior-tty}.
|
|
|
|
@cindex inferior tty
|
|
@cindex set inferior controlling terminal
|
|
You can use the @code{show inferior-tty} command to tell @value{GDBN} to
|
|
display the name of the terminal that will be used for future runs of your
|
|
program.
|
|
|
|
@table @code
|
|
@item set inferior-tty /dev/ttyb
|
|
@kindex set inferior-tty
|
|
Set the tty for the program being debugged to /dev/ttyb.
|
|
|
|
@item show inferior-tty
|
|
@kindex show inferior-tty
|
|
Show the current tty for the program being debugged.
|
|
@end table
|
|
|
|
@node Attach
|
|
@section Debugging an Already-running Process
|
|
@kindex attach
|
|
@cindex attach
|
|
|
|
@table @code
|
|
@item attach @var{process-id}
|
|
This command attaches to a running process---one that was started
|
|
outside @value{GDBN}. (@code{info files} shows your active
|
|
targets.) The command takes as argument a process ID. The usual way to
|
|
find out the @var{process-id} of a Unix process is with the @code{ps} utility,
|
|
or with the @samp{jobs -l} shell command.
|
|
|
|
@code{attach} does not repeat if you press @key{RET} a second time after
|
|
executing the command.
|
|
@end table
|
|
|
|
To use @code{attach}, your program must be running in an environment
|
|
which supports processes; for example, @code{attach} does not work for
|
|
programs on bare-board targets that lack an operating system. You must
|
|
also have permission to send the process a signal.
|
|
|
|
When you use @code{attach}, the debugger finds the program running in
|
|
the process first by looking in the current working directory, then (if
|
|
the program is not found) by using the source file search path
|
|
(@pxref{Source Path, ,Specifying Source Directories}). You can also use
|
|
the @code{file} command to load the program. @xref{Files, ,Commands to
|
|
Specify Files}.
|
|
|
|
The first thing @value{GDBN} does after arranging to debug the specified
|
|
process is to stop it. You can examine and modify an attached process
|
|
with all the @value{GDBN} commands that are ordinarily available when
|
|
you start processes with @code{run}. You can insert breakpoints; you
|
|
can step and continue; you can modify storage. If you would rather the
|
|
process continue running, you may use the @code{continue} command after
|
|
attaching @value{GDBN} to the process.
|
|
|
|
@table @code
|
|
@kindex detach
|
|
@item detach
|
|
When you have finished debugging the attached process, you can use the
|
|
@code{detach} command to release it from @value{GDBN} control. Detaching
|
|
the process continues its execution. After the @code{detach} command,
|
|
that process and @value{GDBN} become completely independent once more, and you
|
|
are ready to @code{attach} another process or start one with @code{run}.
|
|
@code{detach} does not repeat if you press @key{RET} again after
|
|
executing the command.
|
|
@end table
|
|
|
|
If you exit @value{GDBN} while you have an attached process, you detach
|
|
that process. If you use the @code{run} command, you kill that process.
|
|
By default, @value{GDBN} asks for confirmation if you try to do either of these
|
|
things; you can control whether or not you need to confirm by using the
|
|
@code{set confirm} command (@pxref{Messages/Warnings, ,Optional Warnings and
|
|
Messages}).
|
|
|
|
@node Kill Process
|
|
@section Killing the Child Process
|
|
|
|
@table @code
|
|
@kindex kill
|
|
@item kill
|
|
Kill the child process in which your program is running under @value{GDBN}.
|
|
@end table
|
|
|
|
This command is useful if you wish to debug a core dump instead of a
|
|
running process. @value{GDBN} ignores any core dump file while your program
|
|
is running.
|
|
|
|
On some operating systems, a program cannot be executed outside @value{GDBN}
|
|
while you have breakpoints set on it inside @value{GDBN}. You can use the
|
|
@code{kill} command in this situation to permit running your program
|
|
outside the debugger.
|
|
|
|
The @code{kill} command is also useful if you wish to recompile and
|
|
relink your program, since on many systems it is impossible to modify an
|
|
executable file while it is running in a process. In this case, when you
|
|
next type @code{run}, @value{GDBN} notices that the file has changed, and
|
|
reads the symbol table again (while trying to preserve your current
|
|
breakpoint settings).
|
|
|
|
@node Inferiors and Programs
|
|
@section Debugging Multiple Inferiors and Programs
|
|
|
|
@value{GDBN} lets you run and debug multiple programs in a single
|
|
session. In addition, @value{GDBN} on some systems may let you run
|
|
several programs simultaneously (otherwise you have to exit from one
|
|
before starting another). In the most general case, you can have
|
|
multiple threads of execution in each of multiple processes, launched
|
|
from multiple executables.
|
|
|
|
@cindex inferior
|
|
@value{GDBN} represents the state of each program execution with an
|
|
object called an @dfn{inferior}. An inferior typically corresponds to
|
|
a process, but is more general and applies also to targets that do not
|
|
have processes. Inferiors may be created before a process runs, and
|
|
may be retained after a process exits. Inferiors have unique
|
|
identifiers that are different from process ids. Usually each
|
|
inferior will also have its own distinct address space, although some
|
|
embedded targets may have several inferiors running in different parts
|
|
of a single address space. Each inferior may in turn have multiple
|
|
threads running in it.
|
|
|
|
To find out what inferiors exist at any moment, use @w{@code{info
|
|
inferiors}}:
|
|
|
|
@table @code
|
|
@kindex info inferiors
|
|
@item info inferiors
|
|
Print a list of all inferiors currently being managed by @value{GDBN}.
|
|
|
|
@value{GDBN} displays for each inferior (in this order):
|
|
|
|
@enumerate
|
|
@item
|
|
the inferior number assigned by @value{GDBN}
|
|
|
|
@item
|
|
the target system's inferior identifier
|
|
|
|
@item
|
|
the name of the executable the inferior is running.
|
|
|
|
@end enumerate
|
|
|
|
@noindent
|
|
An asterisk @samp{*} preceding the @value{GDBN} inferior number
|
|
indicates the current inferior.
|
|
|
|
For example,
|
|
@end table
|
|
@c end table here to get a little more width for example
|
|
|
|
@smallexample
|
|
(@value{GDBP}) info inferiors
|
|
Num Description Executable
|
|
2 process 2307 hello
|
|
* 1 process 3401 goodbye
|
|
@end smallexample
|
|
|
|
To switch focus between inferiors, use the @code{inferior} command:
|
|
|
|
@table @code
|
|
@kindex inferior @var{infno}
|
|
@item inferior @var{infno}
|
|
Make inferior number @var{infno} the current inferior. The argument
|
|
@var{infno} is the inferior number assigned by @value{GDBN}, as shown
|
|
in the first field of the @samp{info inferiors} display.
|
|
@end table
|
|
|
|
|
|
You can get multiple executables into a debugging session via the
|
|
@code{add-inferior} and @w{@code{clone-inferior}} commands. On some
|
|
systems @value{GDBN} can add inferiors to the debug session
|
|
automatically by following calls to @code{fork} and @code{exec}. To
|
|
remove inferiors from the debugging session use the
|
|
@w{@code{remove-inferiors}} command.
|
|
|
|
@table @code
|
|
@kindex add-inferior
|
|
@item add-inferior [ -copies @var{n} ] [ -exec @var{executable} ]
|
|
Adds @var{n} inferiors to be run using @var{executable} as the
|
|
executable. @var{n} defaults to 1. If no executable is specified,
|
|
the inferiors begins empty, with no program. You can still assign or
|
|
change the program assigned to the inferior at any time by using the
|
|
@code{file} command with the executable name as its argument.
|
|
|
|
@kindex clone-inferior
|
|
@item clone-inferior [ -copies @var{n} ] [ @var{infno} ]
|
|
Adds @var{n} inferiors ready to execute the same program as inferior
|
|
@var{infno}. @var{n} defaults to 1. @var{infno} defaults to the
|
|
number of the current inferior. This is a convenient command when you
|
|
want to run another instance of the inferior you are debugging.
|
|
|
|
@smallexample
|
|
(@value{GDBP}) info inferiors
|
|
Num Description Executable
|
|
* 1 process 29964 helloworld
|
|
(@value{GDBP}) clone-inferior
|
|
Added inferior 2.
|
|
1 inferiors added.
|
|
(@value{GDBP}) info inferiors
|
|
Num Description Executable
|
|
2 <null> helloworld
|
|
* 1 process 29964 helloworld
|
|
@end smallexample
|
|
|
|
You can now simply switch focus to inferior 2 and run it.
|
|
|
|
@kindex remove-inferiors
|
|
@item remove-inferiors @var{infno}@dots{}
|
|
Removes the inferior or inferiors @var{infno}@dots{}. It is not
|
|
possible to remove an inferior that is running with this command. For
|
|
those, use the @code{kill} or @code{detach} command first.
|
|
|
|
@end table
|
|
|
|
To quit debugging one of the running inferiors that is not the current
|
|
inferior, you can either detach from it by using the @w{@code{detach
|
|
inferior}} command (allowing it to run independently), or kill it
|
|
using the @w{@code{kill inferiors}} command:
|
|
|
|
@table @code
|
|
@kindex detach inferiors @var{infno}@dots{}
|
|
@item detach inferior @var{infno}@dots{}
|
|
Detach from the inferior or inferiors identified by @value{GDBN}
|
|
inferior number(s) @var{infno}@dots{}. Note that the inferior's entry
|
|
still stays on the list of inferiors shown by @code{info inferiors},
|
|
but its Description will show @samp{<null>}.
|
|
|
|
@kindex kill inferiors @var{infno}@dots{}
|
|
@item kill inferiors @var{infno}@dots{}
|
|
Kill the inferior or inferiors identified by @value{GDBN} inferior
|
|
number(s) @var{infno}@dots{}. Note that the inferior's entry still
|
|
stays on the list of inferiors shown by @code{info inferiors}, but its
|
|
Description will show @samp{<null>}.
|
|
@end table
|
|
|
|
After the successful completion of a command such as @code{detach},
|
|
@code{detach inferiors}, @code{kill} or @code{kill inferiors}, or after
|
|
a normal process exit, the inferior is still valid and listed with
|
|
@code{info inferiors}, ready to be restarted.
|
|
|
|
|
|
To be notified when inferiors are started or exit under @value{GDBN}'s
|
|
control use @w{@code{set print inferior-events}}:
|
|
|
|
@table @code
|
|
@kindex set print inferior-events
|
|
@cindex print messages on inferior start and exit
|
|
@item set print inferior-events
|
|
@itemx set print inferior-events on
|
|
@itemx set print inferior-events off
|
|
The @code{set print inferior-events} command allows you to enable or
|
|
disable printing of messages when @value{GDBN} notices that new
|
|
inferiors have started or that inferiors have exited or have been
|
|
detached. By default, these messages will not be printed.
|
|
|
|
@kindex show print inferior-events
|
|
@item show print inferior-events
|
|
Show whether messages will be printed when @value{GDBN} detects that
|
|
inferiors have started, exited or have been detached.
|
|
@end table
|
|
|
|
Many commands will work the same with multiple programs as with a
|
|
single program: e.g., @code{print myglobal} will simply display the
|
|
value of @code{myglobal} in the current inferior.
|
|
|
|
|
|
Occasionaly, when debugging @value{GDBN} itself, it may be useful to
|
|
get more info about the relationship of inferiors, programs, address
|
|
spaces in a debug session. You can do that with the @w{@code{maint
|
|
info program-spaces}} command.
|
|
|
|
@table @code
|
|
@kindex maint info program-spaces
|
|
@item maint info program-spaces
|
|
Print a list of all program spaces currently being managed by
|
|
@value{GDBN}.
|
|
|
|
@value{GDBN} displays for each program space (in this order):
|
|
|
|
@enumerate
|
|
@item
|
|
the program space number assigned by @value{GDBN}
|
|
|
|
@item
|
|
the name of the executable loaded into the program space, with e.g.,
|
|
the @code{file} command.
|
|
|
|
@end enumerate
|
|
|
|
@noindent
|
|
An asterisk @samp{*} preceding the @value{GDBN} program space number
|
|
indicates the current program space.
|
|
|
|
In addition, below each program space line, @value{GDBN} prints extra
|
|
information that isn't suitable to display in tabular form. For
|
|
example, the list of inferiors bound to the program space.
|
|
|
|
@smallexample
|
|
(@value{GDBP}) maint info program-spaces
|
|
Id Executable
|
|
2 goodbye
|
|
Bound inferiors: ID 1 (process 21561)
|
|
* 1 hello
|
|
@end smallexample
|
|
|
|
Here we can see that no inferior is running the program @code{hello},
|
|
while @code{process 21561} is running the program @code{goodbye}. On
|
|
some targets, it is possible that multiple inferiors are bound to the
|
|
same program space. The most common example is that of debugging both
|
|
the parent and child processes of a @code{vfork} call. For example,
|
|
|
|
@smallexample
|
|
(@value{GDBP}) maint info program-spaces
|
|
Id Executable
|
|
* 1 vfork-test
|
|
Bound inferiors: ID 2 (process 18050), ID 1 (process 18045)
|
|
@end smallexample
|
|
|
|
Here, both inferior 2 and inferior 1 are running in the same program
|
|
space as a result of inferior 1 having executed a @code{vfork} call.
|
|
@end table
|
|
|
|
@node Threads
|
|
@section Debugging Programs with Multiple Threads
|
|
|
|
@cindex threads of execution
|
|
@cindex multiple threads
|
|
@cindex switching threads
|
|
In some operating systems, such as HP-UX and Solaris, a single program
|
|
may have more than one @dfn{thread} of execution. The precise semantics
|
|
of threads differ from one operating system to another, but in general
|
|
the threads of a single program are akin to multiple processes---except
|
|
that they share one address space (that is, they can all examine and
|
|
modify the same variables). On the other hand, each thread has its own
|
|
registers and execution stack, and perhaps private memory.
|
|
|
|
@value{GDBN} provides these facilities for debugging multi-thread
|
|
programs:
|
|
|
|
@itemize @bullet
|
|
@item automatic notification of new threads
|
|
@item @samp{thread @var{threadno}}, a command to switch among threads
|
|
@item @samp{info threads}, a command to inquire about existing threads
|
|
@item @samp{thread apply [@var{threadno}] [@var{all}] @var{args}},
|
|
a command to apply a command to a list of threads
|
|
@item thread-specific breakpoints
|
|
@item @samp{set print thread-events}, which controls printing of
|
|
messages on thread start and exit.
|
|
@item @samp{set libthread-db-search-path @var{path}}, which lets
|
|
the user specify which @code{libthread_db} to use if the default choice
|
|
isn't compatible with the program.
|
|
@end itemize
|
|
|
|
@quotation
|
|
@emph{Warning:} These facilities are not yet available on every
|
|
@value{GDBN} configuration where the operating system supports threads.
|
|
If your @value{GDBN} does not support threads, these commands have no
|
|
effect. For example, a system without thread support shows no output
|
|
from @samp{info threads}, and always rejects the @code{thread} command,
|
|
like this:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) info threads
|
|
(@value{GDBP}) thread 1
|
|
Thread ID 1 not known. Use the "info threads" command to
|
|
see the IDs of currently known threads.
|
|
@end smallexample
|
|
@c FIXME to implementors: how hard would it be to say "sorry, this GDB
|
|
@c doesn't support threads"?
|
|
@end quotation
|
|
|
|
@cindex focus of debugging
|
|
@cindex current thread
|
|
The @value{GDBN} thread debugging facility allows you to observe all
|
|
threads while your program runs---but whenever @value{GDBN} takes
|
|
control, one thread in particular is always the focus of debugging.
|
|
This thread is called the @dfn{current thread}. Debugging commands show
|
|
program information from the perspective of the current thread.
|
|
|
|
@cindex @code{New} @var{systag} message
|
|
@cindex thread identifier (system)
|
|
@c FIXME-implementors!! It would be more helpful if the [New...] message
|
|
@c included GDB's numeric thread handle, so you could just go to that
|
|
@c thread without first checking `info threads'.
|
|
Whenever @value{GDBN} detects a new thread in your program, it displays
|
|
the target system's identification for the thread with a message in the
|
|
form @samp{[New @var{systag}]}. @var{systag} is a thread identifier
|
|
whose form varies depending on the particular system. For example, on
|
|
@sc{gnu}/Linux, you might see
|
|
|
|
@smallexample
|
|
[New Thread 0x41e02940 (LWP 25582)]
|
|
@end smallexample
|
|
|
|
@noindent
|
|
when @value{GDBN} notices a new thread. In contrast, on an SGI system,
|
|
the @var{systag} is simply something like @samp{process 368}, with no
|
|
further qualifier.
|
|
|
|
@c FIXME!! (1) Does the [New...] message appear even for the very first
|
|
@c thread of a program, or does it only appear for the
|
|
@c second---i.e.@: when it becomes obvious we have a multithread
|
|
@c program?
|
|
@c (2) *Is* there necessarily a first thread always? Or do some
|
|
@c multithread systems permit starting a program with multiple
|
|
@c threads ab initio?
|
|
|
|
@cindex thread number
|
|
@cindex thread identifier (GDB)
|
|
For debugging purposes, @value{GDBN} associates its own thread
|
|
number---always a single integer---with each thread in your program.
|
|
|
|
@table @code
|
|
@kindex info threads
|
|
@item info threads @r{[}@var{id}@dots{}@r{]}
|
|
Display a summary of all threads currently in your program. Optional
|
|
argument @var{id}@dots{} is one or more thread ids separated by spaces, and
|
|
means to print information only about the specified thread or threads.
|
|
@value{GDBN} displays for each thread (in this order):
|
|
|
|
@enumerate
|
|
@item
|
|
the thread number assigned by @value{GDBN}
|
|
|
|
@item
|
|
the target system's thread identifier (@var{systag})
|
|
|
|
@item
|
|
the thread's name, if one is known. A thread can either be named by
|
|
the user (see @code{thread name}, below), or, in some cases, by the
|
|
program itself.
|
|
|
|
@item
|
|
the current stack frame summary for that thread
|
|
@end enumerate
|
|
|
|
@noindent
|
|
An asterisk @samp{*} to the left of the @value{GDBN} thread number
|
|
indicates the current thread.
|
|
|
|
For example,
|
|
@end table
|
|
@c end table here to get a little more width for example
|
|
|
|
@smallexample
|
|
(@value{GDBP}) info threads
|
|
Id Target Id Frame
|
|
3 process 35 thread 27 0x34e5 in sigpause ()
|
|
2 process 35 thread 23 0x34e5 in sigpause ()
|
|
* 1 process 35 thread 13 main (argc=1, argv=0x7ffffff8)
|
|
at threadtest.c:68
|
|
@end smallexample
|
|
|
|
On Solaris, you can display more information about user threads with a
|
|
Solaris-specific command:
|
|
|
|
@table @code
|
|
@item maint info sol-threads
|
|
@kindex maint info sol-threads
|
|
@cindex thread info (Solaris)
|
|
Display info on Solaris user threads.
|
|
@end table
|
|
|
|
@table @code
|
|
@kindex thread @var{threadno}
|
|
@item thread @var{threadno}
|
|
Make thread number @var{threadno} the current thread. The command
|
|
argument @var{threadno} is the internal @value{GDBN} thread number, as
|
|
shown in the first field of the @samp{info threads} display.
|
|
@value{GDBN} responds by displaying the system identifier of the thread
|
|
you selected, and its current stack frame summary:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) thread 2
|
|
[Switching to thread 2 (Thread 0xb7fdab70 (LWP 12747))]
|
|
#0 some_function (ignore=0x0) at example.c:8
|
|
8 printf ("hello\n");
|
|
@end smallexample
|
|
|
|
@noindent
|
|
As with the @samp{[New @dots{}]} message, the form of the text after
|
|
@samp{Switching to} depends on your system's conventions for identifying
|
|
threads.
|
|
|
|
@vindex $_thread@r{, convenience variable}
|
|
The debugger convenience variable @samp{$_thread} contains the number
|
|
of the current thread. You may find this useful in writing breakpoint
|
|
conditional expressions, command scripts, and so forth. See
|
|
@xref{Convenience Vars,, Convenience Variables}, for general
|
|
information on convenience variables.
|
|
|
|
@kindex thread apply
|
|
@cindex apply command to several threads
|
|
@item thread apply [@var{threadno} | all] @var{command}
|
|
The @code{thread apply} command allows you to apply the named
|
|
@var{command} to one or more threads. Specify the numbers of the
|
|
threads that you want affected with the command argument
|
|
@var{threadno}. It can be a single thread number, one of the numbers
|
|
shown in the first field of the @samp{info threads} display; or it
|
|
could be a range of thread numbers, as in @code{2-4}. To apply a
|
|
command to all threads, type @kbd{thread apply all @var{command}}.
|
|
|
|
@kindex thread name
|
|
@cindex name a thread
|
|
@item thread name [@var{name}]
|
|
This command assigns a name to the current thread. If no argument is
|
|
given, any existing user-specified name is removed. The thread name
|
|
appears in the @samp{info threads} display.
|
|
|
|
On some systems, such as @sc{gnu}/Linux, @value{GDBN} is able to
|
|
determine the name of the thread as given by the OS. On these
|
|
systems, a name specified with @samp{thread name} will override the
|
|
system-give name, and removing the user-specified name will cause
|
|
@value{GDBN} to once again display the system-specified name.
|
|
|
|
@kindex thread find
|
|
@cindex search for a thread
|
|
@item thread find [@var{regexp}]
|
|
Search for and display thread ids whose name or @var{systag}
|
|
matches the supplied regular expression.
|
|
|
|
As well as being the complement to the @samp{thread name} command,
|
|
this command also allows you to identify a thread by its target
|
|
@var{systag}. For instance, on @sc{gnu}/Linux, the target @var{systag}
|
|
is the LWP id.
|
|
|
|
@smallexample
|
|
(@value{GDBN}) thread find 26688
|
|
Thread 4 has target id 'Thread 0x41e02940 (LWP 26688)'
|
|
(@value{GDBN}) info thread 4
|
|
Id Target Id Frame
|
|
4 Thread 0x41e02940 (LWP 26688) 0x00000031ca6cd372 in select ()
|
|
@end smallexample
|
|
|
|
@kindex set print thread-events
|
|
@cindex print messages on thread start and exit
|
|
@item set print thread-events
|
|
@itemx set print thread-events on
|
|
@itemx set print thread-events off
|
|
The @code{set print thread-events} command allows you to enable or
|
|
disable printing of messages when @value{GDBN} notices that new threads have
|
|
started or that threads have exited. By default, these messages will
|
|
be printed if detection of these events is supported by the target.
|
|
Note that these messages cannot be disabled on all targets.
|
|
|
|
@kindex show print thread-events
|
|
@item show print thread-events
|
|
Show whether messages will be printed when @value{GDBN} detects that threads
|
|
have started and exited.
|
|
@end table
|
|
|
|
@xref{Thread Stops,,Stopping and Starting Multi-thread Programs}, for
|
|
more information about how @value{GDBN} behaves when you stop and start
|
|
programs with multiple threads.
|
|
|
|
@xref{Set Watchpoints,,Setting Watchpoints}, for information about
|
|
watchpoints in programs with multiple threads.
|
|
|
|
@anchor{set libthread-db-search-path}
|
|
@table @code
|
|
@kindex set libthread-db-search-path
|
|
@cindex search path for @code{libthread_db}
|
|
@item set libthread-db-search-path @r{[}@var{path}@r{]}
|
|
If this variable is set, @var{path} is a colon-separated list of
|
|
directories @value{GDBN} will use to search for @code{libthread_db}.
|
|
If you omit @var{path}, @samp{libthread-db-search-path} will be reset to
|
|
its default value (@code{$sdir:$pdir} on @sc{gnu}/Linux and Solaris systems).
|
|
Internally, the default value comes from the @code{LIBTHREAD_DB_SEARCH_PATH}
|
|
macro.
|
|
|
|
On @sc{gnu}/Linux and Solaris systems, @value{GDBN} uses a ``helper''
|
|
@code{libthread_db} library to obtain information about threads in the
|
|
inferior process. @value{GDBN} will use @samp{libthread-db-search-path}
|
|
to find @code{libthread_db}. @value{GDBN} also consults first if inferior
|
|
specific thread debugging library loading is enabled
|
|
by @samp{set auto-load libthread-db} (@pxref{libthread_db.so.1 file}).
|
|
|
|
A special entry @samp{$sdir} for @samp{libthread-db-search-path}
|
|
refers to the default system directories that are
|
|
normally searched for loading shared libraries. The @samp{$sdir} entry
|
|
is the only kind not needing to be enabled by @samp{set auto-load libthread-db}
|
|
(@pxref{libthread_db.so.1 file}).
|
|
|
|
A special entry @samp{$pdir} for @samp{libthread-db-search-path}
|
|
refers to the directory from which @code{libpthread}
|
|
was loaded in the inferior process.
|
|
|
|
For any @code{libthread_db} library @value{GDBN} finds in above directories,
|
|
@value{GDBN} attempts to initialize it with the current inferior process.
|
|
If this initialization fails (which could happen because of a version
|
|
mismatch between @code{libthread_db} and @code{libpthread}), @value{GDBN}
|
|
will unload @code{libthread_db}, and continue with the next directory.
|
|
If none of @code{libthread_db} libraries initialize successfully,
|
|
@value{GDBN} will issue a warning and thread debugging will be disabled.
|
|
|
|
Setting @code{libthread-db-search-path} is currently implemented
|
|
only on some platforms.
|
|
|
|
@kindex show libthread-db-search-path
|
|
@item show libthread-db-search-path
|
|
Display current libthread_db search path.
|
|
|
|
@kindex set debug libthread-db
|
|
@kindex show debug libthread-db
|
|
@cindex debugging @code{libthread_db}
|
|
@item set debug libthread-db
|
|
@itemx show debug libthread-db
|
|
Turns on or off display of @code{libthread_db}-related events.
|
|
Use @code{1} to enable, @code{0} to disable.
|
|
@end table
|
|
|
|
@node Forks
|
|
@section Debugging Forks
|
|
|
|
@cindex fork, debugging programs which call
|
|
@cindex multiple processes
|
|
@cindex processes, multiple
|
|
On most systems, @value{GDBN} has no special support for debugging
|
|
programs which create additional processes using the @code{fork}
|
|
function. When a program forks, @value{GDBN} will continue to debug the
|
|
parent process and the child process will run unimpeded. If you have
|
|
set a breakpoint in any code which the child then executes, the child
|
|
will get a @code{SIGTRAP} signal which (unless it catches the signal)
|
|
will cause it to terminate.
|
|
|
|
However, if you want to debug the child process there is a workaround
|
|
which isn't too painful. Put a call to @code{sleep} in the code which
|
|
the child process executes after the fork. It may be useful to sleep
|
|
only if a certain environment variable is set, or a certain file exists,
|
|
so that the delay need not occur when you don't want to run @value{GDBN}
|
|
on the child. While the child is sleeping, use the @code{ps} program to
|
|
get its process ID. Then tell @value{GDBN} (a new invocation of
|
|
@value{GDBN} if you are also debugging the parent process) to attach to
|
|
the child process (@pxref{Attach}). From that point on you can debug
|
|
the child process just like any other process which you attached to.
|
|
|
|
On some systems, @value{GDBN} provides support for debugging programs that
|
|
create additional processes using the @code{fork} or @code{vfork} functions.
|
|
Currently, the only platforms with this feature are HP-UX (11.x and later
|
|
only?) and @sc{gnu}/Linux (kernel version 2.5.60 and later).
|
|
|
|
By default, when a program forks, @value{GDBN} will continue to debug
|
|
the parent process and the child process will run unimpeded.
|
|
|
|
If you want to follow the child process instead of the parent process,
|
|
use the command @w{@code{set follow-fork-mode}}.
|
|
|
|
@table @code
|
|
@kindex set follow-fork-mode
|
|
@item set follow-fork-mode @var{mode}
|
|
Set the debugger response to a program call of @code{fork} or
|
|
@code{vfork}. A call to @code{fork} or @code{vfork} creates a new
|
|
process. The @var{mode} argument can be:
|
|
|
|
@table @code
|
|
@item parent
|
|
The original process is debugged after a fork. The child process runs
|
|
unimpeded. This is the default.
|
|
|
|
@item child
|
|
The new process is debugged after a fork. The parent process runs
|
|
unimpeded.
|
|
|
|
@end table
|
|
|
|
@kindex show follow-fork-mode
|
|
@item show follow-fork-mode
|
|
Display the current debugger response to a @code{fork} or @code{vfork} call.
|
|
@end table
|
|
|
|
@cindex debugging multiple processes
|
|
On Linux, if you want to debug both the parent and child processes, use the
|
|
command @w{@code{set detach-on-fork}}.
|
|
|
|
@table @code
|
|
@kindex set detach-on-fork
|
|
@item set detach-on-fork @var{mode}
|
|
Tells gdb whether to detach one of the processes after a fork, or
|
|
retain debugger control over them both.
|
|
|
|
@table @code
|
|
@item on
|
|
The child process (or parent process, depending on the value of
|
|
@code{follow-fork-mode}) will be detached and allowed to run
|
|
independently. This is the default.
|
|
|
|
@item off
|
|
Both processes will be held under the control of @value{GDBN}.
|
|
One process (child or parent, depending on the value of
|
|
@code{follow-fork-mode}) is debugged as usual, while the other
|
|
is held suspended.
|
|
|
|
@end table
|
|
|
|
@kindex show detach-on-fork
|
|
@item show detach-on-fork
|
|
Show whether detach-on-fork mode is on/off.
|
|
@end table
|
|
|
|
If you choose to set @samp{detach-on-fork} mode off, then @value{GDBN}
|
|
will retain control of all forked processes (including nested forks).
|
|
You can list the forked processes under the control of @value{GDBN} by
|
|
using the @w{@code{info inferiors}} command, and switch from one fork
|
|
to another by using the @code{inferior} command (@pxref{Inferiors and
|
|
Programs, ,Debugging Multiple Inferiors and Programs}).
|
|
|
|
To quit debugging one of the forked processes, you can either detach
|
|
from it by using the @w{@code{detach inferiors}} command (allowing it
|
|
to run independently), or kill it using the @w{@code{kill inferiors}}
|
|
command. @xref{Inferiors and Programs, ,Debugging Multiple Inferiors
|
|
and Programs}.
|
|
|
|
If you ask to debug a child process and a @code{vfork} is followed by an
|
|
@code{exec}, @value{GDBN} executes the new target up to the first
|
|
breakpoint in the new target. If you have a breakpoint set on
|
|
@code{main} in your original program, the breakpoint will also be set on
|
|
the child process's @code{main}.
|
|
|
|
On some systems, when a child process is spawned by @code{vfork}, you
|
|
cannot debug the child or parent until an @code{exec} call completes.
|
|
|
|
If you issue a @code{run} command to @value{GDBN} after an @code{exec}
|
|
call executes, the new target restarts. To restart the parent
|
|
process, use the @code{file} command with the parent executable name
|
|
as its argument. By default, after an @code{exec} call executes,
|
|
@value{GDBN} discards the symbols of the previous executable image.
|
|
You can change this behaviour with the @w{@code{set follow-exec-mode}}
|
|
command.
|
|
|
|
@table @code
|
|
@kindex set follow-exec-mode
|
|
@item set follow-exec-mode @var{mode}
|
|
|
|
Set debugger response to a program call of @code{exec}. An
|
|
@code{exec} call replaces the program image of a process.
|
|
|
|
@code{follow-exec-mode} can be:
|
|
|
|
@table @code
|
|
@item new
|
|
@value{GDBN} creates a new inferior and rebinds the process to this
|
|
new inferior. The program the process was running before the
|
|
@code{exec} call can be restarted afterwards by restarting the
|
|
original inferior.
|
|
|
|
For example:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) info inferiors
|
|
(gdb) info inferior
|
|
Id Description Executable
|
|
* 1 <null> prog1
|
|
(@value{GDBP}) run
|
|
process 12020 is executing new program: prog2
|
|
Program exited normally.
|
|
(@value{GDBP}) info inferiors
|
|
Id Description Executable
|
|
* 2 <null> prog2
|
|
1 <null> prog1
|
|
@end smallexample
|
|
|
|
@item same
|
|
@value{GDBN} keeps the process bound to the same inferior. The new
|
|
executable image replaces the previous executable loaded in the
|
|
inferior. Restarting the inferior after the @code{exec} call, with
|
|
e.g., the @code{run} command, restarts the executable the process was
|
|
running after the @code{exec} call. This is the default mode.
|
|
|
|
For example:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) info inferiors
|
|
Id Description Executable
|
|
* 1 <null> prog1
|
|
(@value{GDBP}) run
|
|
process 12020 is executing new program: prog2
|
|
Program exited normally.
|
|
(@value{GDBP}) info inferiors
|
|
Id Description Executable
|
|
* 1 <null> prog2
|
|
@end smallexample
|
|
|
|
@end table
|
|
@end table
|
|
|
|
You can use the @code{catch} command to make @value{GDBN} stop whenever
|
|
a @code{fork}, @code{vfork}, or @code{exec} call is made. @xref{Set
|
|
Catchpoints, ,Setting Catchpoints}.
|
|
|
|
@node Checkpoint/Restart
|
|
@section Setting a @emph{Bookmark} to Return to Later
|
|
|
|
@cindex checkpoint
|
|
@cindex restart
|
|
@cindex bookmark
|
|
@cindex snapshot of a process
|
|
@cindex rewind program state
|
|
|
|
On certain operating systems@footnote{Currently, only
|
|
@sc{gnu}/Linux.}, @value{GDBN} is able to save a @dfn{snapshot} of a
|
|
program's state, called a @dfn{checkpoint}, and come back to it
|
|
later.
|
|
|
|
Returning to a checkpoint effectively undoes everything that has
|
|
happened in the program since the @code{checkpoint} was saved. This
|
|
includes changes in memory, registers, and even (within some limits)
|
|
system state. Effectively, it is like going back in time to the
|
|
moment when the checkpoint was saved.
|
|
|
|
Thus, if you're stepping thru a program and you think you're
|
|
getting close to the point where things go wrong, you can save
|
|
a checkpoint. Then, if you accidentally go too far and miss
|
|
the critical statement, instead of having to restart your program
|
|
from the beginning, you can just go back to the checkpoint and
|
|
start again from there.
|
|
|
|
This can be especially useful if it takes a lot of time or
|
|
steps to reach the point where you think the bug occurs.
|
|
|
|
To use the @code{checkpoint}/@code{restart} method of debugging:
|
|
|
|
@table @code
|
|
@kindex checkpoint
|
|
@item checkpoint
|
|
Save a snapshot of the debugged program's current execution state.
|
|
The @code{checkpoint} command takes no arguments, but each checkpoint
|
|
is assigned a small integer id, similar to a breakpoint id.
|
|
|
|
@kindex info checkpoints
|
|
@item info checkpoints
|
|
List the checkpoints that have been saved in the current debugging
|
|
session. For each checkpoint, the following information will be
|
|
listed:
|
|
|
|
@table @code
|
|
@item Checkpoint ID
|
|
@item Process ID
|
|
@item Code Address
|
|
@item Source line, or label
|
|
@end table
|
|
|
|
@kindex restart @var{checkpoint-id}
|
|
@item restart @var{checkpoint-id}
|
|
Restore the program state that was saved as checkpoint number
|
|
@var{checkpoint-id}. All program variables, registers, stack frames
|
|
etc.@: will be returned to the values that they had when the checkpoint
|
|
was saved. In essence, gdb will ``wind back the clock'' to the point
|
|
in time when the checkpoint was saved.
|
|
|
|
Note that breakpoints, @value{GDBN} variables, command history etc.
|
|
are not affected by restoring a checkpoint. In general, a checkpoint
|
|
only restores things that reside in the program being debugged, not in
|
|
the debugger.
|
|
|
|
@kindex delete checkpoint @var{checkpoint-id}
|
|
@item delete checkpoint @var{checkpoint-id}
|
|
Delete the previously-saved checkpoint identified by @var{checkpoint-id}.
|
|
|
|
@end table
|
|
|
|
Returning to a previously saved checkpoint will restore the user state
|
|
of the program being debugged, plus a significant subset of the system
|
|
(OS) state, including file pointers. It won't ``un-write'' data from
|
|
a file, but it will rewind the file pointer to the previous location,
|
|
so that the previously written data can be overwritten. For files
|
|
opened in read mode, the pointer will also be restored so that the
|
|
previously read data can be read again.
|
|
|
|
Of course, characters that have been sent to a printer (or other
|
|
external device) cannot be ``snatched back'', and characters received
|
|
from eg.@: a serial device can be removed from internal program buffers,
|
|
but they cannot be ``pushed back'' into the serial pipeline, ready to
|
|
be received again. Similarly, the actual contents of files that have
|
|
been changed cannot be restored (at this time).
|
|
|
|
However, within those constraints, you actually can ``rewind'' your
|
|
program to a previously saved point in time, and begin debugging it
|
|
again --- and you can change the course of events so as to debug a
|
|
different execution path this time.
|
|
|
|
@cindex checkpoints and process id
|
|
Finally, there is one bit of internal program state that will be
|
|
different when you return to a checkpoint --- the program's process
|
|
id. Each checkpoint will have a unique process id (or @var{pid}),
|
|
and each will be different from the program's original @var{pid}.
|
|
If your program has saved a local copy of its process id, this could
|
|
potentially pose a problem.
|
|
|
|
@subsection A Non-obvious Benefit of Using Checkpoints
|
|
|
|
On some systems such as @sc{gnu}/Linux, address space randomization
|
|
is performed on new processes for security reasons. This makes it
|
|
difficult or impossible to set a breakpoint, or watchpoint, on an
|
|
absolute address if you have to restart the program, since the
|
|
absolute location of a symbol will change from one execution to the
|
|
next.
|
|
|
|
A checkpoint, however, is an @emph{identical} copy of a process.
|
|
Therefore if you create a checkpoint at (eg.@:) the start of main,
|
|
and simply return to that checkpoint instead of restarting the
|
|
process, you can avoid the effects of address randomization and
|
|
your symbols will all stay in the same place.
|
|
|
|
@node Stopping
|
|
@chapter Stopping and Continuing
|
|
|
|
The principal purposes of using a debugger are so that you can stop your
|
|
program before it terminates; or so that, if your program runs into
|
|
trouble, you can investigate and find out why.
|
|
|
|
Inside @value{GDBN}, your program may stop for any of several reasons,
|
|
such as a signal, a breakpoint, or reaching a new line after a
|
|
@value{GDBN} command such as @code{step}. You may then examine and
|
|
change variables, set new breakpoints or remove old ones, and then
|
|
continue execution. Usually, the messages shown by @value{GDBN} provide
|
|
ample explanation of the status of your program---but you can also
|
|
explicitly request this information at any time.
|
|
|
|
@table @code
|
|
@kindex info program
|
|
@item info program
|
|
Display information about the status of your program: whether it is
|
|
running or not, what process it is, and why it stopped.
|
|
@end table
|
|
|
|
@menu
|
|
* Breakpoints:: Breakpoints, watchpoints, and catchpoints
|
|
* Continuing and Stepping:: Resuming execution
|
|
* Skipping Over Functions and Files::
|
|
Skipping over functions and files
|
|
* Signals:: Signals
|
|
* Thread Stops:: Stopping and starting multi-thread programs
|
|
@end menu
|
|
|
|
@node Breakpoints
|
|
@section Breakpoints, Watchpoints, and Catchpoints
|
|
|
|
@cindex breakpoints
|
|
A @dfn{breakpoint} makes your program stop whenever a certain point in
|
|
the program is reached. For each breakpoint, you can add conditions to
|
|
control in finer detail whether your program stops. You can set
|
|
breakpoints with the @code{break} command and its variants (@pxref{Set
|
|
Breaks, ,Setting Breakpoints}), to specify the place where your program
|
|
should stop by line number, function name or exact address in the
|
|
program.
|
|
|
|
On some systems, you can set breakpoints in shared libraries before
|
|
the executable is run. There is a minor limitation on HP-UX systems:
|
|
you must wait until the executable is run in order to set breakpoints
|
|
in shared library routines that are not called directly by the program
|
|
(for example, routines that are arguments in a @code{pthread_create}
|
|
call).
|
|
|
|
@cindex watchpoints
|
|
@cindex data breakpoints
|
|
@cindex memory tracing
|
|
@cindex breakpoint on memory address
|
|
@cindex breakpoint on variable modification
|
|
A @dfn{watchpoint} is a special breakpoint that stops your program
|
|
when the value of an expression changes. The expression may be a value
|
|
of a variable, or it could involve values of one or more variables
|
|
combined by operators, such as @samp{a + b}. This is sometimes called
|
|
@dfn{data breakpoints}. You must use a different command to set
|
|
watchpoints (@pxref{Set Watchpoints, ,Setting Watchpoints}), but aside
|
|
from that, you can manage a watchpoint like any other breakpoint: you
|
|
enable, disable, and delete both breakpoints and watchpoints using the
|
|
same commands.
|
|
|
|
You can arrange to have values from your program displayed automatically
|
|
whenever @value{GDBN} stops at a breakpoint. @xref{Auto Display,,
|
|
Automatic Display}.
|
|
|
|
@cindex catchpoints
|
|
@cindex breakpoint on events
|
|
A @dfn{catchpoint} is another special breakpoint that stops your program
|
|
when a certain kind of event occurs, such as the throwing of a C@t{++}
|
|
exception or the loading of a library. As with watchpoints, you use a
|
|
different command to set a catchpoint (@pxref{Set Catchpoints, ,Setting
|
|
Catchpoints}), but aside from that, you can manage a catchpoint like any
|
|
other breakpoint. (To stop when your program receives a signal, use the
|
|
@code{handle} command; see @ref{Signals, ,Signals}.)
|
|
|
|
@cindex breakpoint numbers
|
|
@cindex numbers for breakpoints
|
|
@value{GDBN} assigns a number to each breakpoint, watchpoint, or
|
|
catchpoint when you create it; these numbers are successive integers
|
|
starting with one. In many of the commands for controlling various
|
|
features of breakpoints you use the breakpoint number to say which
|
|
breakpoint you want to change. Each breakpoint may be @dfn{enabled} or
|
|
@dfn{disabled}; if disabled, it has no effect on your program until you
|
|
enable it again.
|
|
|
|
@cindex breakpoint ranges
|
|
@cindex ranges of breakpoints
|
|
Some @value{GDBN} commands accept a range of breakpoints on which to
|
|
operate. A breakpoint range is either a single breakpoint number, like
|
|
@samp{5}, or two such numbers, in increasing order, separated by a
|
|
hyphen, like @samp{5-7}. When a breakpoint range is given to a command,
|
|
all breakpoints in that range are operated on.
|
|
|
|
@menu
|
|
* Set Breaks:: Setting breakpoints
|
|
* Set Watchpoints:: Setting watchpoints
|
|
* Set Catchpoints:: Setting catchpoints
|
|
* Delete Breaks:: Deleting breakpoints
|
|
* Disabling:: Disabling breakpoints
|
|
* Conditions:: Break conditions
|
|
* Break Commands:: Breakpoint command lists
|
|
* Dynamic Printf:: Dynamic printf
|
|
* Save Breakpoints:: How to save breakpoints in a file
|
|
* Static Probe Points:: Listing static probe points
|
|
* Error in Breakpoints:: ``Cannot insert breakpoints''
|
|
* Breakpoint-related Warnings:: ``Breakpoint address adjusted...''
|
|
@end menu
|
|
|
|
@node Set Breaks
|
|
@subsection Setting Breakpoints
|
|
|
|
@c FIXME LMB what does GDB do if no code on line of breakpt?
|
|
@c consider in particular declaration with/without initialization.
|
|
@c
|
|
@c FIXME 2 is there stuff on this already? break at fun start, already init?
|
|
|
|
@kindex break
|
|
@kindex b @r{(@code{break})}
|
|
@vindex $bpnum@r{, convenience variable}
|
|
@cindex latest breakpoint
|
|
Breakpoints are set with the @code{break} command (abbreviated
|
|
@code{b}). The debugger convenience variable @samp{$bpnum} records the
|
|
number of the breakpoint you've set most recently; see @ref{Convenience
|
|
Vars,, Convenience Variables}, for a discussion of what you can do with
|
|
convenience variables.
|
|
|
|
@table @code
|
|
@item break @var{location}
|
|
Set a breakpoint at the given @var{location}, which can specify a
|
|
function name, a line number, or an address of an instruction.
|
|
(@xref{Specify Location}, for a list of all the possible ways to
|
|
specify a @var{location}.) The breakpoint will stop your program just
|
|
before it executes any of the code in the specified @var{location}.
|
|
|
|
When using source languages that permit overloading of symbols, such as
|
|
C@t{++}, a function name may refer to more than one possible place to break.
|
|
@xref{Ambiguous Expressions,,Ambiguous Expressions}, for a discussion of
|
|
that situation.
|
|
|
|
It is also possible to insert a breakpoint that will stop the program
|
|
only if a specific thread (@pxref{Thread-Specific Breakpoints})
|
|
or a specific task (@pxref{Ada Tasks}) hits that breakpoint.
|
|
|
|
@item break
|
|
When called without any arguments, @code{break} sets a breakpoint at
|
|
the next instruction to be executed in the selected stack frame
|
|
(@pxref{Stack, ,Examining the Stack}). In any selected frame but the
|
|
innermost, this makes your program stop as soon as control
|
|
returns to that frame. This is similar to the effect of a
|
|
@code{finish} command in the frame inside the selected frame---except
|
|
that @code{finish} does not leave an active breakpoint. If you use
|
|
@code{break} without an argument in the innermost frame, @value{GDBN} stops
|
|
the next time it reaches the current location; this may be useful
|
|
inside loops.
|
|
|
|
@value{GDBN} normally ignores breakpoints when it resumes execution, until at
|
|
least one instruction has been executed. If it did not do this, you
|
|
would be unable to proceed past a breakpoint without first disabling the
|
|
breakpoint. This rule applies whether or not the breakpoint already
|
|
existed when your program stopped.
|
|
|
|
@item break @dots{} if @var{cond}
|
|
Set a breakpoint with condition @var{cond}; evaluate the expression
|
|
@var{cond} each time the breakpoint is reached, and stop only if the
|
|
value is nonzero---that is, if @var{cond} evaluates as true.
|
|
@samp{@dots{}} stands for one of the possible arguments described
|
|
above (or no argument) specifying where to break. @xref{Conditions,
|
|
,Break Conditions}, for more information on breakpoint conditions.
|
|
|
|
@kindex tbreak
|
|
@item tbreak @var{args}
|
|
Set a breakpoint enabled only for one stop. @var{args} are the
|
|
same as for the @code{break} command, and the breakpoint is set in the same
|
|
way, but the breakpoint is automatically deleted after the first time your
|
|
program stops there. @xref{Disabling, ,Disabling Breakpoints}.
|
|
|
|
@kindex hbreak
|
|
@cindex hardware breakpoints
|
|
@item hbreak @var{args}
|
|
Set a hardware-assisted breakpoint. @var{args} are the same as for the
|
|
@code{break} command and the breakpoint is set in the same way, but the
|
|
breakpoint requires hardware support and some target hardware may not
|
|
have this support. The main purpose of this is EPROM/ROM code
|
|
debugging, so you can set a breakpoint at an instruction without
|
|
changing the instruction. This can be used with the new trap-generation
|
|
provided by SPARClite DSU and most x86-based targets. These targets
|
|
will generate traps when a program accesses some data or instruction
|
|
address that is assigned to the debug registers. However the hardware
|
|
breakpoint registers can take a limited number of breakpoints. For
|
|
example, on the DSU, only two data breakpoints can be set at a time, and
|
|
@value{GDBN} will reject this command if more than two are used. Delete
|
|
or disable unused hardware breakpoints before setting new ones
|
|
(@pxref{Disabling, ,Disabling Breakpoints}).
|
|
@xref{Conditions, ,Break Conditions}.
|
|
For remote targets, you can restrict the number of hardware
|
|
breakpoints @value{GDBN} will use, see @ref{set remote
|
|
hardware-breakpoint-limit}.
|
|
|
|
@kindex thbreak
|
|
@item thbreak @var{args}
|
|
Set a hardware-assisted breakpoint enabled only for one stop. @var{args}
|
|
are the same as for the @code{hbreak} command and the breakpoint is set in
|
|
the same way. However, like the @code{tbreak} command,
|
|
the breakpoint is automatically deleted after the
|
|
first time your program stops there. Also, like the @code{hbreak}
|
|
command, the breakpoint requires hardware support and some target hardware
|
|
may not have this support. @xref{Disabling, ,Disabling Breakpoints}.
|
|
See also @ref{Conditions, ,Break Conditions}.
|
|
|
|
@kindex rbreak
|
|
@cindex regular expression
|
|
@cindex breakpoints at functions matching a regexp
|
|
@cindex set breakpoints in many functions
|
|
@item rbreak @var{regex}
|
|
Set breakpoints on all functions matching the regular expression
|
|
@var{regex}. This command sets an unconditional breakpoint on all
|
|
matches, printing a list of all breakpoints it set. Once these
|
|
breakpoints are set, they are treated just like the breakpoints set with
|
|
the @code{break} command. You can delete them, disable them, or make
|
|
them conditional the same way as any other breakpoint.
|
|
|
|
The syntax of the regular expression is the standard one used with tools
|
|
like @file{grep}. Note that this is different from the syntax used by
|
|
shells, so for instance @code{foo*} matches all functions that include
|
|
an @code{fo} followed by zero or more @code{o}s. There is an implicit
|
|
@code{.*} leading and trailing the regular expression you supply, so to
|
|
match only functions that begin with @code{foo}, use @code{^foo}.
|
|
|
|
@cindex non-member C@t{++} functions, set breakpoint in
|
|
When debugging C@t{++} programs, @code{rbreak} is useful for setting
|
|
breakpoints on overloaded functions that are not members of any special
|
|
classes.
|
|
|
|
@cindex set breakpoints on all functions
|
|
The @code{rbreak} command can be used to set breakpoints in
|
|
@strong{all} the functions in a program, like this:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) rbreak .
|
|
@end smallexample
|
|
|
|
@item rbreak @var{file}:@var{regex}
|
|
If @code{rbreak} is called with a filename qualification, it limits
|
|
the search for functions matching the given regular expression to the
|
|
specified @var{file}. This can be used, for example, to set breakpoints on
|
|
every function in a given file:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) rbreak file.c:.
|
|
@end smallexample
|
|
|
|
The colon separating the filename qualifier from the regex may
|
|
optionally be surrounded by spaces.
|
|
|
|
@kindex info breakpoints
|
|
@cindex @code{$_} and @code{info breakpoints}
|
|
@item info breakpoints @r{[}@var{n}@dots{}@r{]}
|
|
@itemx info break @r{[}@var{n}@dots{}@r{]}
|
|
Print a table of all breakpoints, watchpoints, and catchpoints set and
|
|
not deleted. Optional argument @var{n} means print information only
|
|
about the specified breakpoint(s) (or watchpoint(s) or catchpoint(s)).
|
|
For each breakpoint, following columns are printed:
|
|
|
|
@table @emph
|
|
@item Breakpoint Numbers
|
|
@item Type
|
|
Breakpoint, watchpoint, or catchpoint.
|
|
@item Disposition
|
|
Whether the breakpoint is marked to be disabled or deleted when hit.
|
|
@item Enabled or Disabled
|
|
Enabled breakpoints are marked with @samp{y}. @samp{n} marks breakpoints
|
|
that are not enabled.
|
|
@item Address
|
|
Where the breakpoint is in your program, as a memory address. For a
|
|
pending breakpoint whose address is not yet known, this field will
|
|
contain @samp{<PENDING>}. Such breakpoint won't fire until a shared
|
|
library that has the symbol or line referred by breakpoint is loaded.
|
|
See below for details. A breakpoint with several locations will
|
|
have @samp{<MULTIPLE>} in this field---see below for details.
|
|
@item What
|
|
Where the breakpoint is in the source for your program, as a file and
|
|
line number. For a pending breakpoint, the original string passed to
|
|
the breakpoint command will be listed as it cannot be resolved until
|
|
the appropriate shared library is loaded in the future.
|
|
@end table
|
|
|
|
@noindent
|
|
If a breakpoint is conditional, there are two evaluation modes: ``host'' and
|
|
``target''. If mode is ``host'', breakpoint condition evaluation is done by
|
|
@value{GDBN} on the host's side. If it is ``target'', then the condition
|
|
is evaluated by the target. The @code{info break} command shows
|
|
the condition on the line following the affected breakpoint, together with
|
|
its condition evaluation mode in between parentheses.
|
|
|
|
Breakpoint commands, if any, are listed after that. A pending breakpoint is
|
|
allowed to have a condition specified for it. The condition is not parsed for
|
|
validity until a shared library is loaded that allows the pending
|
|
breakpoint to resolve to a valid location.
|
|
|
|
@noindent
|
|
@code{info break} with a breakpoint
|
|
number @var{n} as argument lists only that breakpoint. The
|
|
convenience variable @code{$_} and the default examining-address for
|
|
the @code{x} command are set to the address of the last breakpoint
|
|
listed (@pxref{Memory, ,Examining Memory}).
|
|
|
|
@noindent
|
|
@code{info break} displays a count of the number of times the breakpoint
|
|
has been hit. This is especially useful in conjunction with the
|
|
@code{ignore} command. You can ignore a large number of breakpoint
|
|
hits, look at the breakpoint info to see how many times the breakpoint
|
|
was hit, and then run again, ignoring one less than that number. This
|
|
will get you quickly to the last hit of that breakpoint.
|
|
|
|
@noindent
|
|
For a breakpoints with an enable count (xref) greater than 1,
|
|
@code{info break} also displays that count.
|
|
|
|
@end table
|
|
|
|
@value{GDBN} allows you to set any number of breakpoints at the same place in
|
|
your program. There is nothing silly or meaningless about this. When
|
|
the breakpoints are conditional, this is even useful
|
|
(@pxref{Conditions, ,Break Conditions}).
|
|
|
|
@cindex multiple locations, breakpoints
|
|
@cindex breakpoints, multiple locations
|
|
It is possible that a breakpoint corresponds to several locations
|
|
in your program. Examples of this situation are:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
Multiple functions in the program may have the same name.
|
|
|
|
@item
|
|
For a C@t{++} constructor, the @value{NGCC} compiler generates several
|
|
instances of the function body, used in different cases.
|
|
|
|
@item
|
|
For a C@t{++} template function, a given line in the function can
|
|
correspond to any number of instantiations.
|
|
|
|
@item
|
|
For an inlined function, a given source line can correspond to
|
|
several places where that function is inlined.
|
|
@end itemize
|
|
|
|
In all those cases, @value{GDBN} will insert a breakpoint at all
|
|
the relevant locations.
|
|
|
|
A breakpoint with multiple locations is displayed in the breakpoint
|
|
table using several rows---one header row, followed by one row for
|
|
each breakpoint location. The header row has @samp{<MULTIPLE>} in the
|
|
address column. The rows for individual locations contain the actual
|
|
addresses for locations, and show the functions to which those
|
|
locations belong. The number column for a location is of the form
|
|
@var{breakpoint-number}.@var{location-number}.
|
|
|
|
For example:
|
|
|
|
@smallexample
|
|
Num Type Disp Enb Address What
|
|
1 breakpoint keep y <MULTIPLE>
|
|
stop only if i==1
|
|
breakpoint already hit 1 time
|
|
1.1 y 0x080486a2 in void foo<int>() at t.cc:8
|
|
1.2 y 0x080486ca in void foo<double>() at t.cc:8
|
|
@end smallexample
|
|
|
|
Each location can be individually enabled or disabled by passing
|
|
@var{breakpoint-number}.@var{location-number} as argument to the
|
|
@code{enable} and @code{disable} commands. Note that you cannot
|
|
delete the individual locations from the list, you can only delete the
|
|
entire list of locations that belong to their parent breakpoint (with
|
|
the @kbd{delete @var{num}} command, where @var{num} is the number of
|
|
the parent breakpoint, 1 in the above example). Disabling or enabling
|
|
the parent breakpoint (@pxref{Disabling}) affects all of the locations
|
|
that belong to that breakpoint.
|
|
|
|
@cindex pending breakpoints
|
|
It's quite common to have a breakpoint inside a shared library.
|
|
Shared libraries can be loaded and unloaded explicitly,
|
|
and possibly repeatedly, as the program is executed. To support
|
|
this use case, @value{GDBN} updates breakpoint locations whenever
|
|
any shared library is loaded or unloaded. Typically, you would
|
|
set a breakpoint in a shared library at the beginning of your
|
|
debugging session, when the library is not loaded, and when the
|
|
symbols from the library are not available. When you try to set
|
|
breakpoint, @value{GDBN} will ask you if you want to set
|
|
a so called @dfn{pending breakpoint}---breakpoint whose address
|
|
is not yet resolved.
|
|
|
|
After the program is run, whenever a new shared library is loaded,
|
|
@value{GDBN} reevaluates all the breakpoints. When a newly loaded
|
|
shared library contains the symbol or line referred to by some
|
|
pending breakpoint, that breakpoint is resolved and becomes an
|
|
ordinary breakpoint. When a library is unloaded, all breakpoints
|
|
that refer to its symbols or source lines become pending again.
|
|
|
|
This logic works for breakpoints with multiple locations, too. For
|
|
example, if you have a breakpoint in a C@t{++} template function, and
|
|
a newly loaded shared library has an instantiation of that template,
|
|
a new location is added to the list of locations for the breakpoint.
|
|
|
|
Except for having unresolved address, pending breakpoints do not
|
|
differ from regular breakpoints. You can set conditions or commands,
|
|
enable and disable them and perform other breakpoint operations.
|
|
|
|
@value{GDBN} provides some additional commands for controlling what
|
|
happens when the @samp{break} command cannot resolve breakpoint
|
|
address specification to an address:
|
|
|
|
@kindex set breakpoint pending
|
|
@kindex show breakpoint pending
|
|
@table @code
|
|
@item set breakpoint pending auto
|
|
This is the default behavior. When @value{GDBN} cannot find the breakpoint
|
|
location, it queries you whether a pending breakpoint should be created.
|
|
|
|
@item set breakpoint pending on
|
|
This indicates that an unrecognized breakpoint location should automatically
|
|
result in a pending breakpoint being created.
|
|
|
|
@item set breakpoint pending off
|
|
This indicates that pending breakpoints are not to be created. Any
|
|
unrecognized breakpoint location results in an error. This setting does
|
|
not affect any pending breakpoints previously created.
|
|
|
|
@item show breakpoint pending
|
|
Show the current behavior setting for creating pending breakpoints.
|
|
@end table
|
|
|
|
The settings above only affect the @code{break} command and its
|
|
variants. Once breakpoint is set, it will be automatically updated
|
|
as shared libraries are loaded and unloaded.
|
|
|
|
@cindex automatic hardware breakpoints
|
|
For some targets, @value{GDBN} can automatically decide if hardware or
|
|
software breakpoints should be used, depending on whether the
|
|
breakpoint address is read-only or read-write. This applies to
|
|
breakpoints set with the @code{break} command as well as to internal
|
|
breakpoints set by commands like @code{next} and @code{finish}. For
|
|
breakpoints set with @code{hbreak}, @value{GDBN} will always use hardware
|
|
breakpoints.
|
|
|
|
You can control this automatic behaviour with the following commands::
|
|
|
|
@kindex set breakpoint auto-hw
|
|
@kindex show breakpoint auto-hw
|
|
@table @code
|
|
@item set breakpoint auto-hw on
|
|
This is the default behavior. When @value{GDBN} sets a breakpoint, it
|
|
will try to use the target memory map to decide if software or hardware
|
|
breakpoint must be used.
|
|
|
|
@item set breakpoint auto-hw off
|
|
This indicates @value{GDBN} should not automatically select breakpoint
|
|
type. If the target provides a memory map, @value{GDBN} will warn when
|
|
trying to set software breakpoint at a read-only address.
|
|
@end table
|
|
|
|
@value{GDBN} normally implements breakpoints by replacing the program code
|
|
at the breakpoint address with a special instruction, which, when
|
|
executed, given control to the debugger. By default, the program
|
|
code is so modified only when the program is resumed. As soon as
|
|
the program stops, @value{GDBN} restores the original instructions. This
|
|
behaviour guards against leaving breakpoints inserted in the
|
|
target should gdb abrubptly disconnect. However, with slow remote
|
|
targets, inserting and removing breakpoint can reduce the performance.
|
|
This behavior can be controlled with the following commands::
|
|
|
|
@kindex set breakpoint always-inserted
|
|
@kindex show breakpoint always-inserted
|
|
@table @code
|
|
@item set breakpoint always-inserted off
|
|
All breakpoints, including newly added by the user, are inserted in
|
|
the target only when the target is resumed. All breakpoints are
|
|
removed from the target when it stops.
|
|
|
|
@item set breakpoint always-inserted on
|
|
Causes all breakpoints to be inserted in the target at all times. If
|
|
the user adds a new breakpoint, or changes an existing breakpoint, the
|
|
breakpoints in the target are updated immediately. A breakpoint is
|
|
removed from the target only when breakpoint itself is removed.
|
|
|
|
@cindex non-stop mode, and @code{breakpoint always-inserted}
|
|
@item set breakpoint always-inserted auto
|
|
This is the default mode. If @value{GDBN} is controlling the inferior
|
|
in non-stop mode (@pxref{Non-Stop Mode}), gdb behaves as if
|
|
@code{breakpoint always-inserted} mode is on. If @value{GDBN} is
|
|
controlling the inferior in all-stop mode, @value{GDBN} behaves as if
|
|
@code{breakpoint always-inserted} mode is off.
|
|
@end table
|
|
|
|
@value{GDBN} handles conditional breakpoints by evaluating these conditions
|
|
when a breakpoint breaks. If the condition is true, then the process being
|
|
debugged stops, otherwise the process is resumed.
|
|
|
|
If the target supports evaluating conditions on its end, @value{GDBN} may
|
|
download the breakpoint, together with its conditions, to it.
|
|
|
|
This feature can be controlled via the following commands:
|
|
|
|
@kindex set breakpoint condition-evaluation
|
|
@kindex show breakpoint condition-evaluation
|
|
@table @code
|
|
@item set breakpoint condition-evaluation host
|
|
This option commands @value{GDBN} to evaluate the breakpoint
|
|
conditions on the host's side. Unconditional breakpoints are sent to
|
|
the target which in turn receives the triggers and reports them back to GDB
|
|
for condition evaluation. This is the standard evaluation mode.
|
|
|
|
@item set breakpoint condition-evaluation target
|
|
This option commands @value{GDBN} to download breakpoint conditions
|
|
to the target at the moment of their insertion. The target
|
|
is responsible for evaluating the conditional expression and reporting
|
|
breakpoint stop events back to @value{GDBN} whenever the condition
|
|
is true. Due to limitations of target-side evaluation, some conditions
|
|
cannot be evaluated there, e.g., conditions that depend on local data
|
|
that is only known to the host. Examples include
|
|
conditional expressions involving convenience variables, complex types
|
|
that cannot be handled by the agent expression parser and expressions
|
|
that are too long to be sent over to the target, specially when the
|
|
target is a remote system. In these cases, the conditions will be
|
|
evaluated by @value{GDBN}.
|
|
|
|
@item set breakpoint condition-evaluation auto
|
|
This is the default mode. If the target supports evaluating breakpoint
|
|
conditions on its end, @value{GDBN} will download breakpoint conditions to
|
|
the target (limitations mentioned previously apply). If the target does
|
|
not support breakpoint condition evaluation, then @value{GDBN} will fallback
|
|
to evaluating all these conditions on the host's side.
|
|
@end table
|
|
|
|
|
|
@cindex negative breakpoint numbers
|
|
@cindex internal @value{GDBN} breakpoints
|
|
@value{GDBN} itself sometimes sets breakpoints in your program for
|
|
special purposes, such as proper handling of @code{longjmp} (in C
|
|
programs). These internal breakpoints are assigned negative numbers,
|
|
starting with @code{-1}; @samp{info breakpoints} does not display them.
|
|
You can see these breakpoints with the @value{GDBN} maintenance command
|
|
@samp{maint info breakpoints} (@pxref{maint info breakpoints}).
|
|
|
|
|
|
@node Set Watchpoints
|
|
@subsection Setting Watchpoints
|
|
|
|
@cindex setting watchpoints
|
|
You can use a watchpoint to stop execution whenever the value of an
|
|
expression changes, without having to predict a particular place where
|
|
this may happen. (This is sometimes called a @dfn{data breakpoint}.)
|
|
The expression may be as simple as the value of a single variable, or
|
|
as complex as many variables combined by operators. Examples include:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
A reference to the value of a single variable.
|
|
|
|
@item
|
|
An address cast to an appropriate data type. For example,
|
|
@samp{*(int *)0x12345678} will watch a 4-byte region at the specified
|
|
address (assuming an @code{int} occupies 4 bytes).
|
|
|
|
@item
|
|
An arbitrarily complex expression, such as @samp{a*b + c/d}. The
|
|
expression can use any operators valid in the program's native
|
|
language (@pxref{Languages}).
|
|
@end itemize
|
|
|
|
You can set a watchpoint on an expression even if the expression can
|
|
not be evaluated yet. For instance, you can set a watchpoint on
|
|
@samp{*global_ptr} before @samp{global_ptr} is initialized.
|
|
@value{GDBN} will stop when your program sets @samp{global_ptr} and
|
|
the expression produces a valid value. If the expression becomes
|
|
valid in some other way than changing a variable (e.g.@: if the memory
|
|
pointed to by @samp{*global_ptr} becomes readable as the result of a
|
|
@code{malloc} call), @value{GDBN} may not stop until the next time
|
|
the expression changes.
|
|
|
|
@cindex software watchpoints
|
|
@cindex hardware watchpoints
|
|
Depending on your system, watchpoints may be implemented in software or
|
|
hardware. @value{GDBN} does software watchpointing by single-stepping your
|
|
program and testing the variable's value each time, which is hundreds of
|
|
times slower than normal execution. (But this may still be worth it, to
|
|
catch errors where you have no clue what part of your program is the
|
|
culprit.)
|
|
|
|
On some systems, such as HP-UX, PowerPC, @sc{gnu}/Linux and most other
|
|
x86-based targets, @value{GDBN} includes support for hardware
|
|
watchpoints, which do not slow down the running of your program.
|
|
|
|
@table @code
|
|
@kindex watch
|
|
@item watch @r{[}-l@r{|}-location@r{]} @var{expr} @r{[}thread @var{threadnum}@r{]} @r{[}mask @var{maskvalue}@r{]}
|
|
Set a watchpoint for an expression. @value{GDBN} will break when the
|
|
expression @var{expr} is written into by the program and its value
|
|
changes. The simplest (and the most popular) use of this command is
|
|
to watch the value of a single variable:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) watch foo
|
|
@end smallexample
|
|
|
|
If the command includes a @code{@r{[}thread @var{threadnum}@r{]}}
|
|
argument, @value{GDBN} breaks only when the thread identified by
|
|
@var{threadnum} changes the value of @var{expr}. If any other threads
|
|
change the value of @var{expr}, @value{GDBN} will not break. Note
|
|
that watchpoints restricted to a single thread in this way only work
|
|
with Hardware Watchpoints.
|
|
|
|
Ordinarily a watchpoint respects the scope of variables in @var{expr}
|
|
(see below). The @code{-location} argument tells @value{GDBN} to
|
|
instead watch the memory referred to by @var{expr}. In this case,
|
|
@value{GDBN} will evaluate @var{expr}, take the address of the result,
|
|
and watch the memory at that address. The type of the result is used
|
|
to determine the size of the watched memory. If the expression's
|
|
result does not have an address, then @value{GDBN} will print an
|
|
error.
|
|
|
|
The @code{@r{[}mask @var{maskvalue}@r{]}} argument allows creation
|
|
of masked watchpoints, if the current architecture supports this
|
|
feature (e.g., PowerPC Embedded architecture, see @ref{PowerPC
|
|
Embedded}.) A @dfn{masked watchpoint} specifies a mask in addition
|
|
to an address to watch. The mask specifies that some bits of an address
|
|
(the bits which are reset in the mask) should be ignored when matching
|
|
the address accessed by the inferior against the watchpoint address.
|
|
Thus, a masked watchpoint watches many addresses simultaneously---those
|
|
addresses whose unmasked bits are identical to the unmasked bits in the
|
|
watchpoint address. The @code{mask} argument implies @code{-location}.
|
|
Examples:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) watch foo mask 0xffff00ff
|
|
(@value{GDBP}) watch *0xdeadbeef mask 0xffffff00
|
|
@end smallexample
|
|
|
|
@kindex rwatch
|
|
@item rwatch @r{[}-l@r{|}-location@r{]} @var{expr} @r{[}thread @var{threadnum}@r{]} @r{[}mask @var{maskvalue}@r{]}
|
|
Set a watchpoint that will break when the value of @var{expr} is read
|
|
by the program.
|
|
|
|
@kindex awatch
|
|
@item awatch @r{[}-l@r{|}-location@r{]} @var{expr} @r{[}thread @var{threadnum}@r{]} @r{[}mask @var{maskvalue}@r{]}
|
|
Set a watchpoint that will break when @var{expr} is either read from
|
|
or written into by the program.
|
|
|
|
@kindex info watchpoints @r{[}@var{n}@dots{}@r{]}
|
|
@item info watchpoints @r{[}@var{n}@dots{}@r{]}
|
|
This command prints a list of watchpoints, using the same format as
|
|
@code{info break} (@pxref{Set Breaks}).
|
|
@end table
|
|
|
|
If you watch for a change in a numerically entered address you need to
|
|
dereference it, as the address itself is just a constant number which will
|
|
never change. @value{GDBN} refuses to create a watchpoint that watches
|
|
a never-changing value:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) watch 0x600850
|
|
Cannot watch constant value 0x600850.
|
|
(@value{GDBP}) watch *(int *) 0x600850
|
|
Watchpoint 1: *(int *) 6293584
|
|
@end smallexample
|
|
|
|
@value{GDBN} sets a @dfn{hardware watchpoint} if possible. Hardware
|
|
watchpoints execute very quickly, and the debugger reports a change in
|
|
value at the exact instruction where the change occurs. If @value{GDBN}
|
|
cannot set a hardware watchpoint, it sets a software watchpoint, which
|
|
executes more slowly and reports the change in value at the next
|
|
@emph{statement}, not the instruction, after the change occurs.
|
|
|
|
@cindex use only software watchpoints
|
|
You can force @value{GDBN} to use only software watchpoints with the
|
|
@kbd{set can-use-hw-watchpoints 0} command. With this variable set to
|
|
zero, @value{GDBN} will never try to use hardware watchpoints, even if
|
|
the underlying system supports them. (Note that hardware-assisted
|
|
watchpoints that were set @emph{before} setting
|
|
@code{can-use-hw-watchpoints} to zero will still use the hardware
|
|
mechanism of watching expression values.)
|
|
|
|
@table @code
|
|
@item set can-use-hw-watchpoints
|
|
@kindex set can-use-hw-watchpoints
|
|
Set whether or not to use hardware watchpoints.
|
|
|
|
@item show can-use-hw-watchpoints
|
|
@kindex show can-use-hw-watchpoints
|
|
Show the current mode of using hardware watchpoints.
|
|
@end table
|
|
|
|
For remote targets, you can restrict the number of hardware
|
|
watchpoints @value{GDBN} will use, see @ref{set remote
|
|
hardware-breakpoint-limit}.
|
|
|
|
When you issue the @code{watch} command, @value{GDBN} reports
|
|
|
|
@smallexample
|
|
Hardware watchpoint @var{num}: @var{expr}
|
|
@end smallexample
|
|
|
|
@noindent
|
|
if it was able to set a hardware watchpoint.
|
|
|
|
Currently, the @code{awatch} and @code{rwatch} commands can only set
|
|
hardware watchpoints, because accesses to data that don't change the
|
|
value of the watched expression cannot be detected without examining
|
|
every instruction as it is being executed, and @value{GDBN} does not do
|
|
that currently. If @value{GDBN} finds that it is unable to set a
|
|
hardware breakpoint with the @code{awatch} or @code{rwatch} command, it
|
|
will print a message like this:
|
|
|
|
@smallexample
|
|
Expression cannot be implemented with read/access watchpoint.
|
|
@end smallexample
|
|
|
|
Sometimes, @value{GDBN} cannot set a hardware watchpoint because the
|
|
data type of the watched expression is wider than what a hardware
|
|
watchpoint on the target machine can handle. For example, some systems
|
|
can only watch regions that are up to 4 bytes wide; on such systems you
|
|
cannot set hardware watchpoints for an expression that yields a
|
|
double-precision floating-point number (which is typically 8 bytes
|
|
wide). As a work-around, it might be possible to break the large region
|
|
into a series of smaller ones and watch them with separate watchpoints.
|
|
|
|
If you set too many hardware watchpoints, @value{GDBN} might be unable
|
|
to insert all of them when you resume the execution of your program.
|
|
Since the precise number of active watchpoints is unknown until such
|
|
time as the program is about to be resumed, @value{GDBN} might not be
|
|
able to warn you about this when you set the watchpoints, and the
|
|
warning will be printed only when the program is resumed:
|
|
|
|
@smallexample
|
|
Hardware watchpoint @var{num}: Could not insert watchpoint
|
|
@end smallexample
|
|
|
|
@noindent
|
|
If this happens, delete or disable some of the watchpoints.
|
|
|
|
Watching complex expressions that reference many variables can also
|
|
exhaust the resources available for hardware-assisted watchpoints.
|
|
That's because @value{GDBN} needs to watch every variable in the
|
|
expression with separately allocated resources.
|
|
|
|
If you call a function interactively using @code{print} or @code{call},
|
|
any watchpoints you have set will be inactive until @value{GDBN} reaches another
|
|
kind of breakpoint or the call completes.
|
|
|
|
@value{GDBN} automatically deletes watchpoints that watch local
|
|
(automatic) variables, or expressions that involve such variables, when
|
|
they go out of scope, that is, when the execution leaves the block in
|
|
which these variables were defined. In particular, when the program
|
|
being debugged terminates, @emph{all} local variables go out of scope,
|
|
and so only watchpoints that watch global variables remain set. If you
|
|
rerun the program, you will need to set all such watchpoints again. One
|
|
way of doing that would be to set a code breakpoint at the entry to the
|
|
@code{main} function and when it breaks, set all the watchpoints.
|
|
|
|
@cindex watchpoints and threads
|
|
@cindex threads and watchpoints
|
|
In multi-threaded programs, watchpoints will detect changes to the
|
|
watched expression from every thread.
|
|
|
|
@quotation
|
|
@emph{Warning:} In multi-threaded programs, software watchpoints
|
|
have only limited usefulness. If @value{GDBN} creates a software
|
|
watchpoint, it can only watch the value of an expression @emph{in a
|
|
single thread}. If you are confident that the expression can only
|
|
change due to the current thread's activity (and if you are also
|
|
confident that no other thread can become current), then you can use
|
|
software watchpoints as usual. However, @value{GDBN} may not notice
|
|
when a non-current thread's activity changes the expression. (Hardware
|
|
watchpoints, in contrast, watch an expression in all threads.)
|
|
@end quotation
|
|
|
|
@xref{set remote hardware-watchpoint-limit}.
|
|
|
|
@node Set Catchpoints
|
|
@subsection Setting Catchpoints
|
|
@cindex catchpoints, setting
|
|
@cindex exception handlers
|
|
@cindex event handling
|
|
|
|
You can use @dfn{catchpoints} to cause the debugger to stop for certain
|
|
kinds of program events, such as C@t{++} exceptions or the loading of a
|
|
shared library. Use the @code{catch} command to set a catchpoint.
|
|
|
|
@table @code
|
|
@kindex catch
|
|
@item catch @var{event}
|
|
Stop when @var{event} occurs. @var{event} can be any of the following:
|
|
@table @code
|
|
@item throw
|
|
@cindex stop on C@t{++} exceptions
|
|
The throwing of a C@t{++} exception.
|
|
|
|
@item catch
|
|
The catching of a C@t{++} exception.
|
|
|
|
@item exception
|
|
@cindex Ada exception catching
|
|
@cindex catch Ada exceptions
|
|
An Ada exception being raised. If an exception name is specified
|
|
at the end of the command (eg @code{catch exception Program_Error}),
|
|
the debugger will stop only when this specific exception is raised.
|
|
Otherwise, the debugger stops execution when any Ada exception is raised.
|
|
|
|
When inserting an exception catchpoint on a user-defined exception whose
|
|
name is identical to one of the exceptions defined by the language, the
|
|
fully qualified name must be used as the exception name. Otherwise,
|
|
@value{GDBN} will assume that it should stop on the pre-defined exception
|
|
rather than the user-defined one. For instance, assuming an exception
|
|
called @code{Constraint_Error} is defined in package @code{Pck}, then
|
|
the command to use to catch such exceptions is @kbd{catch exception
|
|
Pck.Constraint_Error}.
|
|
|
|
@item exception unhandled
|
|
An exception that was raised but is not handled by the program.
|
|
|
|
@item assert
|
|
A failed Ada assertion.
|
|
|
|
@item exec
|
|
@cindex break on fork/exec
|
|
A call to @code{exec}. This is currently only available for HP-UX
|
|
and @sc{gnu}/Linux.
|
|
|
|
@item syscall
|
|
@itemx syscall @r{[}@var{name} @r{|} @var{number}@r{]} @dots{}
|
|
@cindex break on a system call.
|
|
A call to or return from a system call, a.k.a.@: @dfn{syscall}. A
|
|
syscall is a mechanism for application programs to request a service
|
|
from the operating system (OS) or one of the OS system services.
|
|
@value{GDBN} can catch some or all of the syscalls issued by the
|
|
debuggee, and show the related information for each syscall. If no
|
|
argument is specified, calls to and returns from all system calls
|
|
will be caught.
|
|
|
|
@var{name} can be any system call name that is valid for the
|
|
underlying OS. Just what syscalls are valid depends on the OS. On
|
|
GNU and Unix systems, you can find the full list of valid syscall
|
|
names on @file{/usr/include/asm/unistd.h}.
|
|
|
|
@c For MS-Windows, the syscall names and the corresponding numbers
|
|
@c can be found, e.g., on this URL:
|
|
@c http://www.metasploit.com/users/opcode/syscalls.html
|
|
@c but we don't support Windows syscalls yet.
|
|
|
|
Normally, @value{GDBN} knows in advance which syscalls are valid for
|
|
each OS, so you can use the @value{GDBN} command-line completion
|
|
facilities (@pxref{Completion,, command completion}) to list the
|
|
available choices.
|
|
|
|
You may also specify the system call numerically. A syscall's
|
|
number is the value passed to the OS's syscall dispatcher to
|
|
identify the requested service. When you specify the syscall by its
|
|
name, @value{GDBN} uses its database of syscalls to convert the name
|
|
into the corresponding numeric code, but using the number directly
|
|
may be useful if @value{GDBN}'s database does not have the complete
|
|
list of syscalls on your system (e.g., because @value{GDBN} lags
|
|
behind the OS upgrades).
|
|
|
|
The example below illustrates how this command works if you don't provide
|
|
arguments to it:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) catch syscall
|
|
Catchpoint 1 (syscall)
|
|
(@value{GDBP}) r
|
|
Starting program: /tmp/catch-syscall
|
|
|
|
Catchpoint 1 (call to syscall 'close'), \
|
|
0xffffe424 in __kernel_vsyscall ()
|
|
(@value{GDBP}) c
|
|
Continuing.
|
|
|
|
Catchpoint 1 (returned from syscall 'close'), \
|
|
0xffffe424 in __kernel_vsyscall ()
|
|
(@value{GDBP})
|
|
@end smallexample
|
|
|
|
Here is an example of catching a system call by name:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) catch syscall chroot
|
|
Catchpoint 1 (syscall 'chroot' [61])
|
|
(@value{GDBP}) r
|
|
Starting program: /tmp/catch-syscall
|
|
|
|
Catchpoint 1 (call to syscall 'chroot'), \
|
|
0xffffe424 in __kernel_vsyscall ()
|
|
(@value{GDBP}) c
|
|
Continuing.
|
|
|
|
Catchpoint 1 (returned from syscall 'chroot'), \
|
|
0xffffe424 in __kernel_vsyscall ()
|
|
(@value{GDBP})
|
|
@end smallexample
|
|
|
|
An example of specifying a system call numerically. In the case
|
|
below, the syscall number has a corresponding entry in the XML
|
|
file, so @value{GDBN} finds its name and prints it:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) catch syscall 252
|
|
Catchpoint 1 (syscall(s) 'exit_group')
|
|
(@value{GDBP}) r
|
|
Starting program: /tmp/catch-syscall
|
|
|
|
Catchpoint 1 (call to syscall 'exit_group'), \
|
|
0xffffe424 in __kernel_vsyscall ()
|
|
(@value{GDBP}) c
|
|
Continuing.
|
|
|
|
Program exited normally.
|
|
(@value{GDBP})
|
|
@end smallexample
|
|
|
|
However, there can be situations when there is no corresponding name
|
|
in XML file for that syscall number. In this case, @value{GDBN} prints
|
|
a warning message saying that it was not able to find the syscall name,
|
|
but the catchpoint will be set anyway. See the example below:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) catch syscall 764
|
|
warning: The number '764' does not represent a known syscall.
|
|
Catchpoint 2 (syscall 764)
|
|
(@value{GDBP})
|
|
@end smallexample
|
|
|
|
If you configure @value{GDBN} using the @samp{--without-expat} option,
|
|
it will not be able to display syscall names. Also, if your
|
|
architecture does not have an XML file describing its system calls,
|
|
you will not be able to see the syscall names. It is important to
|
|
notice that these two features are used for accessing the syscall
|
|
name database. In either case, you will see a warning like this:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) catch syscall
|
|
warning: Could not open "syscalls/i386-linux.xml"
|
|
warning: Could not load the syscall XML file 'syscalls/i386-linux.xml'.
|
|
GDB will not be able to display syscall names.
|
|
Catchpoint 1 (syscall)
|
|
(@value{GDBP})
|
|
@end smallexample
|
|
|
|
Of course, the file name will change depending on your architecture and system.
|
|
|
|
Still using the example above, you can also try to catch a syscall by its
|
|
number. In this case, you would see something like:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) catch syscall 252
|
|
Catchpoint 1 (syscall(s) 252)
|
|
@end smallexample
|
|
|
|
Again, in this case @value{GDBN} would not be able to display syscall's names.
|
|
|
|
@item fork
|
|
A call to @code{fork}. This is currently only available for HP-UX
|
|
and @sc{gnu}/Linux.
|
|
|
|
@item vfork
|
|
A call to @code{vfork}. This is currently only available for HP-UX
|
|
and @sc{gnu}/Linux.
|
|
|
|
@item load @r{[}regexp@r{]}
|
|
@itemx unload @r{[}regexp@r{]}
|
|
The loading or unloading of a shared library. If @var{regexp} is
|
|
given, then the catchpoint will stop only if the regular expression
|
|
matches one of the affected libraries.
|
|
|
|
@end table
|
|
|
|
@item tcatch @var{event}
|
|
Set a catchpoint that is enabled only for one stop. The catchpoint is
|
|
automatically deleted after the first time the event is caught.
|
|
|
|
@end table
|
|
|
|
Use the @code{info break} command to list the current catchpoints.
|
|
|
|
There are currently some limitations to C@t{++} exception handling
|
|
(@code{catch throw} and @code{catch catch}) in @value{GDBN}:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
If you call a function interactively, @value{GDBN} normally returns
|
|
control to you when the function has finished executing. If the call
|
|
raises an exception, however, the call may bypass the mechanism that
|
|
returns control to you and cause your program either to abort or to
|
|
simply continue running until it hits a breakpoint, catches a signal
|
|
that @value{GDBN} is listening for, or exits. This is the case even if
|
|
you set a catchpoint for the exception; catchpoints on exceptions are
|
|
disabled within interactive calls.
|
|
|
|
@item
|
|
You cannot raise an exception interactively.
|
|
|
|
@item
|
|
You cannot install an exception handler interactively.
|
|
@end itemize
|
|
|
|
@cindex raise exceptions
|
|
Sometimes @code{catch} is not the best way to debug exception handling:
|
|
if you need to know exactly where an exception is raised, it is better to
|
|
stop @emph{before} the exception handler is called, since that way you
|
|
can see the stack before any unwinding takes place. If you set a
|
|
breakpoint in an exception handler instead, it may not be easy to find
|
|
out where the exception was raised.
|
|
|
|
To stop just before an exception handler is called, you need some
|
|
knowledge of the implementation. In the case of @sc{gnu} C@t{++}, exceptions are
|
|
raised by calling a library function named @code{__raise_exception}
|
|
which has the following ANSI C interface:
|
|
|
|
@smallexample
|
|
/* @var{addr} is where the exception identifier is stored.
|
|
@var{id} is the exception identifier. */
|
|
void __raise_exception (void **addr, void *id);
|
|
@end smallexample
|
|
|
|
@noindent
|
|
To make the debugger catch all exceptions before any stack
|
|
unwinding takes place, set a breakpoint on @code{__raise_exception}
|
|
(@pxref{Breakpoints, ,Breakpoints; Watchpoints; and Exceptions}).
|
|
|
|
With a conditional breakpoint (@pxref{Conditions, ,Break Conditions})
|
|
that depends on the value of @var{id}, you can stop your program when
|
|
a specific exception is raised. You can use multiple conditional
|
|
breakpoints to stop your program when any of a number of exceptions are
|
|
raised.
|
|
|
|
|
|
@node Delete Breaks
|
|
@subsection Deleting Breakpoints
|
|
|
|
@cindex clearing breakpoints, watchpoints, catchpoints
|
|
@cindex deleting breakpoints, watchpoints, catchpoints
|
|
It is often necessary to eliminate a breakpoint, watchpoint, or
|
|
catchpoint once it has done its job and you no longer want your program
|
|
to stop there. This is called @dfn{deleting} the breakpoint. A
|
|
breakpoint that has been deleted no longer exists; it is forgotten.
|
|
|
|
With the @code{clear} command you can delete breakpoints according to
|
|
where they are in your program. With the @code{delete} command you can
|
|
delete individual breakpoints, watchpoints, or catchpoints by specifying
|
|
their breakpoint numbers.
|
|
|
|
It is not necessary to delete a breakpoint to proceed past it. @value{GDBN}
|
|
automatically ignores breakpoints on the first instruction to be executed
|
|
when you continue execution without changing the execution address.
|
|
|
|
@table @code
|
|
@kindex clear
|
|
@item clear
|
|
Delete any breakpoints at the next instruction to be executed in the
|
|
selected stack frame (@pxref{Selection, ,Selecting a Frame}). When
|
|
the innermost frame is selected, this is a good way to delete a
|
|
breakpoint where your program just stopped.
|
|
|
|
@item clear @var{location}
|
|
Delete any breakpoints set at the specified @var{location}.
|
|
@xref{Specify Location}, for the various forms of @var{location}; the
|
|
most useful ones are listed below:
|
|
|
|
@table @code
|
|
@item clear @var{function}
|
|
@itemx clear @var{filename}:@var{function}
|
|
Delete any breakpoints set at entry to the named @var{function}.
|
|
|
|
@item clear @var{linenum}
|
|
@itemx clear @var{filename}:@var{linenum}
|
|
Delete any breakpoints set at or within the code of the specified
|
|
@var{linenum} of the specified @var{filename}.
|
|
@end table
|
|
|
|
@cindex delete breakpoints
|
|
@kindex delete
|
|
@kindex d @r{(@code{delete})}
|
|
@item delete @r{[}breakpoints@r{]} @r{[}@var{range}@dots{}@r{]}
|
|
Delete the breakpoints, watchpoints, or catchpoints of the breakpoint
|
|
ranges specified as arguments. If no argument is specified, delete all
|
|
breakpoints (@value{GDBN} asks confirmation, unless you have @code{set
|
|
confirm off}). You can abbreviate this command as @code{d}.
|
|
@end table
|
|
|
|
@node Disabling
|
|
@subsection Disabling Breakpoints
|
|
|
|
@cindex enable/disable a breakpoint
|
|
Rather than deleting a breakpoint, watchpoint, or catchpoint, you might
|
|
prefer to @dfn{disable} it. This makes the breakpoint inoperative as if
|
|
it had been deleted, but remembers the information on the breakpoint so
|
|
that you can @dfn{enable} it again later.
|
|
|
|
You disable and enable breakpoints, watchpoints, and catchpoints with
|
|
the @code{enable} and @code{disable} commands, optionally specifying
|
|
one or more breakpoint numbers as arguments. Use @code{info break} to
|
|
print a list of all breakpoints, watchpoints, and catchpoints if you
|
|
do not know which numbers to use.
|
|
|
|
Disabling and enabling a breakpoint that has multiple locations
|
|
affects all of its locations.
|
|
|
|
A breakpoint, watchpoint, or catchpoint can have any of several
|
|
different states of enablement:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
Enabled. The breakpoint stops your program. A breakpoint set
|
|
with the @code{break} command starts out in this state.
|
|
@item
|
|
Disabled. The breakpoint has no effect on your program.
|
|
@item
|
|
Enabled once. The breakpoint stops your program, but then becomes
|
|
disabled.
|
|
@item
|
|
Enabled for a count. The breakpoint stops your program for the next
|
|
N times, then becomes disabled.
|
|
@item
|
|
Enabled for deletion. The breakpoint stops your program, but
|
|
immediately after it does so it is deleted permanently. A breakpoint
|
|
set with the @code{tbreak} command starts out in this state.
|
|
@end itemize
|
|
|
|
You can use the following commands to enable or disable breakpoints,
|
|
watchpoints, and catchpoints:
|
|
|
|
@table @code
|
|
@kindex disable
|
|
@kindex dis @r{(@code{disable})}
|
|
@item disable @r{[}breakpoints@r{]} @r{[}@var{range}@dots{}@r{]}
|
|
Disable the specified breakpoints---or all breakpoints, if none are
|
|
listed. A disabled breakpoint has no effect but is not forgotten. All
|
|
options such as ignore-counts, conditions and commands are remembered in
|
|
case the breakpoint is enabled again later. You may abbreviate
|
|
@code{disable} as @code{dis}.
|
|
|
|
@kindex enable
|
|
@item enable @r{[}breakpoints@r{]} @r{[}@var{range}@dots{}@r{]}
|
|
Enable the specified breakpoints (or all defined breakpoints). They
|
|
become effective once again in stopping your program.
|
|
|
|
@item enable @r{[}breakpoints@r{]} once @var{range}@dots{}
|
|
Enable the specified breakpoints temporarily. @value{GDBN} disables any
|
|
of these breakpoints immediately after stopping your program.
|
|
|
|
@item enable @r{[}breakpoints@r{]} count @var{count} @var{range}@dots{}
|
|
Enable the specified breakpoints temporarily. @value{GDBN} records
|
|
@var{count} with each of the specified breakpoints, and decrements a
|
|
breakpoint's count when it is hit. When any count reaches 0,
|
|
@value{GDBN} disables that breakpoint. If a breakpoint has an ignore
|
|
count (@pxref{Conditions, ,Break Conditions}), that will be
|
|
decremented to 0 before @var{count} is affected.
|
|
|
|
@item enable @r{[}breakpoints@r{]} delete @var{range}@dots{}
|
|
Enable the specified breakpoints to work once, then die. @value{GDBN}
|
|
deletes any of these breakpoints as soon as your program stops there.
|
|
Breakpoints set by the @code{tbreak} command start out in this state.
|
|
@end table
|
|
|
|
@c FIXME: I think the following ``Except for [...] @code{tbreak}'' is
|
|
@c confusing: tbreak is also initially enabled.
|
|
Except for a breakpoint set with @code{tbreak} (@pxref{Set Breaks,
|
|
,Setting Breakpoints}), breakpoints that you set are initially enabled;
|
|
subsequently, they become disabled or enabled only when you use one of
|
|
the commands above. (The command @code{until} can set and delete a
|
|
breakpoint of its own, but it does not change the state of your other
|
|
breakpoints; see @ref{Continuing and Stepping, ,Continuing and
|
|
Stepping}.)
|
|
|
|
@node Conditions
|
|
@subsection Break Conditions
|
|
@cindex conditional breakpoints
|
|
@cindex breakpoint conditions
|
|
|
|
@c FIXME what is scope of break condition expr? Context where wanted?
|
|
@c in particular for a watchpoint?
|
|
The simplest sort of breakpoint breaks every time your program reaches a
|
|
specified place. You can also specify a @dfn{condition} for a
|
|
breakpoint. A condition is just a Boolean expression in your
|
|
programming language (@pxref{Expressions, ,Expressions}). A breakpoint with
|
|
a condition evaluates the expression each time your program reaches it,
|
|
and your program stops only if the condition is @emph{true}.
|
|
|
|
This is the converse of using assertions for program validation; in that
|
|
situation, you want to stop when the assertion is violated---that is,
|
|
when the condition is false. In C, if you want to test an assertion expressed
|
|
by the condition @var{assert}, you should set the condition
|
|
@samp{! @var{assert}} on the appropriate breakpoint.
|
|
|
|
Conditions are also accepted for watchpoints; you may not need them,
|
|
since a watchpoint is inspecting the value of an expression anyhow---but
|
|
it might be simpler, say, to just set a watchpoint on a variable name,
|
|
and specify a condition that tests whether the new value is an interesting
|
|
one.
|
|
|
|
Break conditions can have side effects, and may even call functions in
|
|
your program. This can be useful, for example, to activate functions
|
|
that log program progress, or to use your own print functions to
|
|
format special data structures. The effects are completely predictable
|
|
unless there is another enabled breakpoint at the same address. (In
|
|
that case, @value{GDBN} might see the other breakpoint first and stop your
|
|
program without checking the condition of this one.) Note that
|
|
breakpoint commands are usually more convenient and flexible than break
|
|
conditions for the
|
|
purpose of performing side effects when a breakpoint is reached
|
|
(@pxref{Break Commands, ,Breakpoint Command Lists}).
|
|
|
|
Breakpoint conditions can also be evaluated on the target's side if
|
|
the target supports it. Instead of evaluating the conditions locally,
|
|
@value{GDBN} encodes the expression into an agent expression
|
|
(@pxref{Agent Expressions}) suitable for execution on the target,
|
|
independently of @value{GDBN}. Global variables become raw memory
|
|
locations, locals become stack accesses, and so forth.
|
|
|
|
In this case, @value{GDBN} will only be notified of a breakpoint trigger
|
|
when its condition evaluates to true. This mechanism may provide faster
|
|
response times depending on the performance characteristics of the target
|
|
since it does not need to keep @value{GDBN} informed about
|
|
every breakpoint trigger, even those with false conditions.
|
|
|
|
Break conditions can be specified when a breakpoint is set, by using
|
|
@samp{if} in the arguments to the @code{break} command. @xref{Set
|
|
Breaks, ,Setting Breakpoints}. They can also be changed at any time
|
|
with the @code{condition} command.
|
|
|
|
You can also use the @code{if} keyword with the @code{watch} command.
|
|
The @code{catch} command does not recognize the @code{if} keyword;
|
|
@code{condition} is the only way to impose a further condition on a
|
|
catchpoint.
|
|
|
|
@table @code
|
|
@kindex condition
|
|
@item condition @var{bnum} @var{expression}
|
|
Specify @var{expression} as the break condition for breakpoint,
|
|
watchpoint, or catchpoint number @var{bnum}. After you set a condition,
|
|
breakpoint @var{bnum} stops your program only if the value of
|
|
@var{expression} is true (nonzero, in C). When you use
|
|
@code{condition}, @value{GDBN} checks @var{expression} immediately for
|
|
syntactic correctness, and to determine whether symbols in it have
|
|
referents in the context of your breakpoint. If @var{expression} uses
|
|
symbols not referenced in the context of the breakpoint, @value{GDBN}
|
|
prints an error message:
|
|
|
|
@smallexample
|
|
No symbol "foo" in current context.
|
|
@end smallexample
|
|
|
|
@noindent
|
|
@value{GDBN} does
|
|
not actually evaluate @var{expression} at the time the @code{condition}
|
|
command (or a command that sets a breakpoint with a condition, like
|
|
@code{break if @dots{}}) is given, however. @xref{Expressions, ,Expressions}.
|
|
|
|
@item condition @var{bnum}
|
|
Remove the condition from breakpoint number @var{bnum}. It becomes
|
|
an ordinary unconditional breakpoint.
|
|
@end table
|
|
|
|
@cindex ignore count (of breakpoint)
|
|
A special case of a breakpoint condition is to stop only when the
|
|
breakpoint has been reached a certain number of times. This is so
|
|
useful that there is a special way to do it, using the @dfn{ignore
|
|
count} of the breakpoint. Every breakpoint has an ignore count, which
|
|
is an integer. Most of the time, the ignore count is zero, and
|
|
therefore has no effect. But if your program reaches a breakpoint whose
|
|
ignore count is positive, then instead of stopping, it just decrements
|
|
the ignore count by one and continues. As a result, if the ignore count
|
|
value is @var{n}, the breakpoint does not stop the next @var{n} times
|
|
your program reaches it.
|
|
|
|
@table @code
|
|
@kindex ignore
|
|
@item ignore @var{bnum} @var{count}
|
|
Set the ignore count of breakpoint number @var{bnum} to @var{count}.
|
|
The next @var{count} times the breakpoint is reached, your program's
|
|
execution does not stop; other than to decrement the ignore count, @value{GDBN}
|
|
takes no action.
|
|
|
|
To make the breakpoint stop the next time it is reached, specify
|
|
a count of zero.
|
|
|
|
When you use @code{continue} to resume execution of your program from a
|
|
breakpoint, you can specify an ignore count directly as an argument to
|
|
@code{continue}, rather than using @code{ignore}. @xref{Continuing and
|
|
Stepping,,Continuing and Stepping}.
|
|
|
|
If a breakpoint has a positive ignore count and a condition, the
|
|
condition is not checked. Once the ignore count reaches zero,
|
|
@value{GDBN} resumes checking the condition.
|
|
|
|
You could achieve the effect of the ignore count with a condition such
|
|
as @w{@samp{$foo-- <= 0}} using a debugger convenience variable that
|
|
is decremented each time. @xref{Convenience Vars, ,Convenience
|
|
Variables}.
|
|
@end table
|
|
|
|
Ignore counts apply to breakpoints, watchpoints, and catchpoints.
|
|
|
|
|
|
@node Break Commands
|
|
@subsection Breakpoint Command Lists
|
|
|
|
@cindex breakpoint commands
|
|
You can give any breakpoint (or watchpoint or catchpoint) a series of
|
|
commands to execute when your program stops due to that breakpoint. For
|
|
example, you might want to print the values of certain expressions, or
|
|
enable other breakpoints.
|
|
|
|
@table @code
|
|
@kindex commands
|
|
@kindex end@r{ (breakpoint commands)}
|
|
@item commands @r{[}@var{range}@dots{}@r{]}
|
|
@itemx @dots{} @var{command-list} @dots{}
|
|
@itemx end
|
|
Specify a list of commands for the given breakpoints. The commands
|
|
themselves appear on the following lines. Type a line containing just
|
|
@code{end} to terminate the commands.
|
|
|
|
To remove all commands from a breakpoint, type @code{commands} and
|
|
follow it immediately with @code{end}; that is, give no commands.
|
|
|
|
With no argument, @code{commands} refers to the last breakpoint,
|
|
watchpoint, or catchpoint set (not to the breakpoint most recently
|
|
encountered). If the most recent breakpoints were set with a single
|
|
command, then the @code{commands} will apply to all the breakpoints
|
|
set by that command. This applies to breakpoints set by
|
|
@code{rbreak}, and also applies when a single @code{break} command
|
|
creates multiple breakpoints (@pxref{Ambiguous Expressions,,Ambiguous
|
|
Expressions}).
|
|
@end table
|
|
|
|
Pressing @key{RET} as a means of repeating the last @value{GDBN} command is
|
|
disabled within a @var{command-list}.
|
|
|
|
You can use breakpoint commands to start your program up again. Simply
|
|
use the @code{continue} command, or @code{step}, or any other command
|
|
that resumes execution.
|
|
|
|
Any other commands in the command list, after a command that resumes
|
|
execution, are ignored. This is because any time you resume execution
|
|
(even with a simple @code{next} or @code{step}), you may encounter
|
|
another breakpoint---which could have its own command list, leading to
|
|
ambiguities about which list to execute.
|
|
|
|
@kindex silent
|
|
If the first command you specify in a command list is @code{silent}, the
|
|
usual message about stopping at a breakpoint is not printed. This may
|
|
be desirable for breakpoints that are to print a specific message and
|
|
then continue. If none of the remaining commands print anything, you
|
|
see no sign that the breakpoint was reached. @code{silent} is
|
|
meaningful only at the beginning of a breakpoint command list.
|
|
|
|
The commands @code{echo}, @code{output}, and @code{printf} allow you to
|
|
print precisely controlled output, and are often useful in silent
|
|
breakpoints. @xref{Output, ,Commands for Controlled Output}.
|
|
|
|
For example, here is how you could use breakpoint commands to print the
|
|
value of @code{x} at entry to @code{foo} whenever @code{x} is positive.
|
|
|
|
@smallexample
|
|
break foo if x>0
|
|
commands
|
|
silent
|
|
printf "x is %d\n",x
|
|
cont
|
|
end
|
|
@end smallexample
|
|
|
|
One application for breakpoint commands is to compensate for one bug so
|
|
you can test for another. Put a breakpoint just after the erroneous line
|
|
of code, give it a condition to detect the case in which something
|
|
erroneous has been done, and give it commands to assign correct values
|
|
to any variables that need them. End with the @code{continue} command
|
|
so that your program does not stop, and start with the @code{silent}
|
|
command so that no output is produced. Here is an example:
|
|
|
|
@smallexample
|
|
break 403
|
|
commands
|
|
silent
|
|
set x = y + 4
|
|
cont
|
|
end
|
|
@end smallexample
|
|
|
|
@node Dynamic Printf
|
|
@subsection Dynamic Printf
|
|
|
|
@cindex dynamic printf
|
|
@cindex dprintf
|
|
The dynamic printf command @code{dprintf} combines a breakpoint with
|
|
formatted printing of your program's data to give you the effect of
|
|
inserting @code{printf} calls into your program on-the-fly, without
|
|
having to recompile it.
|
|
|
|
In its most basic form, the output goes to the GDB console. However,
|
|
you can set the variable @code{dprintf-style} for alternate handling.
|
|
For instance, you can ask to format the output by calling your
|
|
program's @code{printf} function. This has the advantage that the
|
|
characters go to the program's output device, so they can recorded in
|
|
redirects to files and so forth.
|
|
|
|
If you are doing remote debugging with a stub or agent, you can also
|
|
ask to have the printf handled by the remote agent. In addition to
|
|
ensuring that the output goes to the remote program's device along
|
|
with any other output the program might produce, you can also ask that
|
|
the dprintf remain active even after disconnecting from the remote
|
|
target. Using the stub/agent is also more efficient, as it can do
|
|
everything without needing to communicate with @value{GDBN}.
|
|
|
|
@table @code
|
|
@kindex dprintf
|
|
@item dprintf @var{location},@var{template},@var{expression}[,@var{expression}@dots{}]
|
|
Whenever execution reaches @var{location}, print the values of one or
|
|
more @var{expressions} under the control of the string @var{template}.
|
|
To print several values, separate them with commas.
|
|
|
|
@item set dprintf-style @var{style}
|
|
Set the dprintf output to be handled in one of several different
|
|
styles enumerated below. A change of style affects all existing
|
|
dynamic printfs immediately. (If you need individual control over the
|
|
print commands, simply define normal breakpoints with
|
|
explicitly-supplied command lists.)
|
|
|
|
@item gdb
|
|
@kindex dprintf-style gdb
|
|
Handle the output using the @value{GDBN} @code{printf} command.
|
|
|
|
@item call
|
|
@kindex dprintf-style call
|
|
Handle the output by calling a function in your program (normally
|
|
@code{printf}).
|
|
|
|
@item agent
|
|
@kindex dprintf-style agent
|
|
Have the remote debugging agent (such as @code{gdbserver}) handle
|
|
the output itself. This style is only available for agents that
|
|
support running commands on the target.
|
|
|
|
@item set dprintf-function @var{function}
|
|
Set the function to call if the dprintf style is @code{call}. By
|
|
default its value is @code{printf}. You may set it to any expression.
|
|
that @value{GDBN} can evaluate to a function, as per the @code{call}
|
|
command.
|
|
|
|
@item set dprintf-channel @var{channel}
|
|
Set a ``channel'' for dprintf. If set to a non-empty value,
|
|
@value{GDBN} will evaluate it as an expression and pass the result as
|
|
a first argument to the @code{dprintf-function}, in the manner of
|
|
@code{fprintf} and similar functions. Otherwise, the dprintf format
|
|
string will be the first argument, in the manner of @code{printf}.
|
|
|
|
As an example, if you wanted @code{dprintf} output to go to a logfile
|
|
that is a standard I/O stream assigned to the variable @code{mylog},
|
|
you could do the following:
|
|
|
|
@example
|
|
(gdb) set dprintf-style call
|
|
(gdb) set dprintf-function fprintf
|
|
(gdb) set dprintf-channel mylog
|
|
(gdb) dprintf 25,"at line 25, glob=%d\n",glob
|
|
Dprintf 1 at 0x123456: file main.c, line 25.
|
|
(gdb) info break
|
|
1 dprintf keep y 0x00123456 in main at main.c:25
|
|
call (void) fprintf (mylog,"at line 25, glob=%d\n",glob)
|
|
continue
|
|
(gdb)
|
|
@end example
|
|
|
|
Note that the @code{info break} displays the dynamic printf commands
|
|
as normal breakpoint commands; you can thus easily see the effect of
|
|
the variable settings.
|
|
|
|
@item set disconnected-dprintf on
|
|
@itemx set disconnected-dprintf off
|
|
@kindex set disconnected-dprintf
|
|
Choose whether @code{dprintf} commands should continue to run if
|
|
@value{GDBN} has disconnected from the target. This only applies
|
|
if the @code{dprintf-style} is @code{agent}.
|
|
|
|
@item show disconnected-dprintf off
|
|
@kindex show disconnected-dprintf
|
|
Show the current choice for disconnected @code{dprintf}.
|
|
|
|
@end table
|
|
|
|
@value{GDBN} does not check the validity of function and channel,
|
|
relying on you to supply values that are meaningful for the contexts
|
|
in which they are being used. For instance, the function and channel
|
|
may be the values of local variables, but if that is the case, then
|
|
all enabled dynamic prints must be at locations within the scope of
|
|
those locals. If evaluation fails, @value{GDBN} will report an error.
|
|
|
|
@node Save Breakpoints
|
|
@subsection How to save breakpoints to a file
|
|
|
|
To save breakpoint definitions to a file use the @w{@code{save
|
|
breakpoints}} command.
|
|
|
|
@table @code
|
|
@kindex save breakpoints
|
|
@cindex save breakpoints to a file for future sessions
|
|
@item save breakpoints [@var{filename}]
|
|
This command saves all current breakpoint definitions together with
|
|
their commands and ignore counts, into a file @file{@var{filename}}
|
|
suitable for use in a later debugging session. This includes all
|
|
types of breakpoints (breakpoints, watchpoints, catchpoints,
|
|
tracepoints). To read the saved breakpoint definitions, use the
|
|
@code{source} command (@pxref{Command Files}). Note that watchpoints
|
|
with expressions involving local variables may fail to be recreated
|
|
because it may not be possible to access the context where the
|
|
watchpoint is valid anymore. Because the saved breakpoint definitions
|
|
are simply a sequence of @value{GDBN} commands that recreate the
|
|
breakpoints, you can edit the file in your favorite editing program,
|
|
and remove the breakpoint definitions you're not interested in, or
|
|
that can no longer be recreated.
|
|
@end table
|
|
|
|
@node Static Probe Points
|
|
@subsection Static Probe Points
|
|
|
|
@cindex static probe point, SystemTap
|
|
@value{GDBN} supports @dfn{SDT} probes in the code. @acronym{SDT} stands
|
|
for Statically Defined Tracing, and the probes are designed to have a tiny
|
|
runtime code and data footprint, and no dynamic relocations. They are
|
|
usable from assembly, C and C@t{++} languages. See
|
|
@uref{http://sourceware.org/systemtap/wiki/UserSpaceProbeImplementation}
|
|
for a good reference on how the @acronym{SDT} probes are implemented.
|
|
|
|
Currently, @code{SystemTap} (@uref{http://sourceware.org/systemtap/})
|
|
@acronym{SDT} probes are supported on ELF-compatible systems. See
|
|
@uref{http://sourceware.org/systemtap/wiki/AddingUserSpaceProbingToApps}
|
|
for more information on how to add @code{SystemTap} @acronym{SDT} probes
|
|
in your applications.
|
|
|
|
@cindex semaphores on static probe points
|
|
Some probes have an associated semaphore variable; for instance, this
|
|
happens automatically if you defined your probe using a DTrace-style
|
|
@file{.d} file. If your probe has a semaphore, @value{GDBN} will
|
|
automatically enable it when you specify a breakpoint using the
|
|
@samp{-probe-stap} notation. But, if you put a breakpoint at a probe's
|
|
location by some other method (e.g., @code{break file:line}), then
|
|
@value{GDBN} will not automatically set the semaphore.
|
|
|
|
You can examine the available static static probes using @code{info
|
|
probes}, with optional arguments:
|
|
|
|
@table @code
|
|
@kindex info probes
|
|
@item info probes stap @r{[}@var{provider} @r{[}@var{name} @r{[}@var{objfile}@r{]}@r{]}@r{]}
|
|
If given, @var{provider} is a regular expression used to match against provider
|
|
names when selecting which probes to list. If omitted, probes by all
|
|
probes from all providers are listed.
|
|
|
|
If given, @var{name} is a regular expression to match against probe names
|
|
when selecting which probes to list. If omitted, probe names are not
|
|
considered when deciding whether to display them.
|
|
|
|
If given, @var{objfile} is a regular expression used to select which
|
|
object files (executable or shared libraries) to examine. If not
|
|
given, all object files are considered.
|
|
|
|
@item info probes all
|
|
List the available static probes, from all types.
|
|
@end table
|
|
|
|
@vindex $_probe_arg@r{, convenience variable}
|
|
A probe may specify up to twelve arguments. These are available at the
|
|
point at which the probe is defined---that is, when the current PC is
|
|
at the probe's location. The arguments are available using the
|
|
convenience variables (@pxref{Convenience Vars})
|
|
@code{$_probe_arg0}@dots{}@code{$_probe_arg11}. Each probe argument is
|
|
an integer of the appropriate size; types are not preserved. The
|
|
convenience variable @code{$_probe_argc} holds the number of arguments
|
|
at the current probe point.
|
|
|
|
These variables are always available, but attempts to access them at
|
|
any location other than a probe point will cause @value{GDBN} to give
|
|
an error message.
|
|
|
|
|
|
@c @ifclear BARETARGET
|
|
@node Error in Breakpoints
|
|
@subsection ``Cannot insert breakpoints''
|
|
|
|
If you request too many active hardware-assisted breakpoints and
|
|
watchpoints, you will see this error message:
|
|
|
|
@c FIXME: the precise wording of this message may change; the relevant
|
|
@c source change is not committed yet (Sep 3, 1999).
|
|
@smallexample
|
|
Stopped; cannot insert breakpoints.
|
|
You may have requested too many hardware breakpoints and watchpoints.
|
|
@end smallexample
|
|
|
|
@noindent
|
|
This message is printed when you attempt to resume the program, since
|
|
only then @value{GDBN} knows exactly how many hardware breakpoints and
|
|
watchpoints it needs to insert.
|
|
|
|
When this message is printed, you need to disable or remove some of the
|
|
hardware-assisted breakpoints and watchpoints, and then continue.
|
|
|
|
@node Breakpoint-related Warnings
|
|
@subsection ``Breakpoint address adjusted...''
|
|
@cindex breakpoint address adjusted
|
|
|
|
Some processor architectures place constraints on the addresses at
|
|
which breakpoints may be placed. For architectures thus constrained,
|
|
@value{GDBN} will attempt to adjust the breakpoint's address to comply
|
|
with the constraints dictated by the architecture.
|
|
|
|
One example of such an architecture is the Fujitsu FR-V. The FR-V is
|
|
a VLIW architecture in which a number of RISC-like instructions may be
|
|
bundled together for parallel execution. The FR-V architecture
|
|
constrains the location of a breakpoint instruction within such a
|
|
bundle to the instruction with the lowest address. @value{GDBN}
|
|
honors this constraint by adjusting a breakpoint's address to the
|
|
first in the bundle.
|
|
|
|
It is not uncommon for optimized code to have bundles which contain
|
|
instructions from different source statements, thus it may happen that
|
|
a breakpoint's address will be adjusted from one source statement to
|
|
another. Since this adjustment may significantly alter @value{GDBN}'s
|
|
breakpoint related behavior from what the user expects, a warning is
|
|
printed when the breakpoint is first set and also when the breakpoint
|
|
is hit.
|
|
|
|
A warning like the one below is printed when setting a breakpoint
|
|
that's been subject to address adjustment:
|
|
|
|
@smallexample
|
|
warning: Breakpoint address adjusted from 0x00010414 to 0x00010410.
|
|
@end smallexample
|
|
|
|
Such warnings are printed both for user settable and @value{GDBN}'s
|
|
internal breakpoints. If you see one of these warnings, you should
|
|
verify that a breakpoint set at the adjusted address will have the
|
|
desired affect. If not, the breakpoint in question may be removed and
|
|
other breakpoints may be set which will have the desired behavior.
|
|
E.g., it may be sufficient to place the breakpoint at a later
|
|
instruction. A conditional breakpoint may also be useful in some
|
|
cases to prevent the breakpoint from triggering too often.
|
|
|
|
@value{GDBN} will also issue a warning when stopping at one of these
|
|
adjusted breakpoints:
|
|
|
|
@smallexample
|
|
warning: Breakpoint 1 address previously adjusted from 0x00010414
|
|
to 0x00010410.
|
|
@end smallexample
|
|
|
|
When this warning is encountered, it may be too late to take remedial
|
|
action except in cases where the breakpoint is hit earlier or more
|
|
frequently than expected.
|
|
|
|
@node Continuing and Stepping
|
|
@section Continuing and Stepping
|
|
|
|
@cindex stepping
|
|
@cindex continuing
|
|
@cindex resuming execution
|
|
@dfn{Continuing} means resuming program execution until your program
|
|
completes normally. In contrast, @dfn{stepping} means executing just
|
|
one more ``step'' of your program, where ``step'' may mean either one
|
|
line of source code, or one machine instruction (depending on what
|
|
particular command you use). Either when continuing or when stepping,
|
|
your program may stop even sooner, due to a breakpoint or a signal. (If
|
|
it stops due to a signal, you may want to use @code{handle}, or use
|
|
@samp{signal 0} to resume execution. @xref{Signals, ,Signals}.)
|
|
|
|
@table @code
|
|
@kindex continue
|
|
@kindex c @r{(@code{continue})}
|
|
@kindex fg @r{(resume foreground execution)}
|
|
@item continue @r{[}@var{ignore-count}@r{]}
|
|
@itemx c @r{[}@var{ignore-count}@r{]}
|
|
@itemx fg @r{[}@var{ignore-count}@r{]}
|
|
Resume program execution, at the address where your program last stopped;
|
|
any breakpoints set at that address are bypassed. The optional argument
|
|
@var{ignore-count} allows you to specify a further number of times to
|
|
ignore a breakpoint at this location; its effect is like that of
|
|
@code{ignore} (@pxref{Conditions, ,Break Conditions}).
|
|
|
|
The argument @var{ignore-count} is meaningful only when your program
|
|
stopped due to a breakpoint. At other times, the argument to
|
|
@code{continue} is ignored.
|
|
|
|
The synonyms @code{c} and @code{fg} (for @dfn{foreground}, as the
|
|
debugged program is deemed to be the foreground program) are provided
|
|
purely for convenience, and have exactly the same behavior as
|
|
@code{continue}.
|
|
@end table
|
|
|
|
To resume execution at a different place, you can use @code{return}
|
|
(@pxref{Returning, ,Returning from a Function}) to go back to the
|
|
calling function; or @code{jump} (@pxref{Jumping, ,Continuing at a
|
|
Different Address}) to go to an arbitrary location in your program.
|
|
|
|
A typical technique for using stepping is to set a breakpoint
|
|
(@pxref{Breakpoints, ,Breakpoints; Watchpoints; and Catchpoints}) at the
|
|
beginning of the function or the section of your program where a problem
|
|
is believed to lie, run your program until it stops at that breakpoint,
|
|
and then step through the suspect area, examining the variables that are
|
|
interesting, until you see the problem happen.
|
|
|
|
@table @code
|
|
@kindex step
|
|
@kindex s @r{(@code{step})}
|
|
@item step
|
|
Continue running your program until control reaches a different source
|
|
line, then stop it and return control to @value{GDBN}. This command is
|
|
abbreviated @code{s}.
|
|
|
|
@quotation
|
|
@c "without debugging information" is imprecise; actually "without line
|
|
@c numbers in the debugging information". (gcc -g1 has debugging info but
|
|
@c not line numbers). But it seems complex to try to make that
|
|
@c distinction here.
|
|
@emph{Warning:} If you use the @code{step} command while control is
|
|
within a function that was compiled without debugging information,
|
|
execution proceeds until control reaches a function that does have
|
|
debugging information. Likewise, it will not step into a function which
|
|
is compiled without debugging information. To step through functions
|
|
without debugging information, use the @code{stepi} command, described
|
|
below.
|
|
@end quotation
|
|
|
|
The @code{step} command only stops at the first instruction of a source
|
|
line. This prevents the multiple stops that could otherwise occur in
|
|
@code{switch} statements, @code{for} loops, etc. @code{step} continues
|
|
to stop if a function that has debugging information is called within
|
|
the line. In other words, @code{step} @emph{steps inside} any functions
|
|
called within the line.
|
|
|
|
Also, the @code{step} command only enters a function if there is line
|
|
number information for the function. Otherwise it acts like the
|
|
@code{next} command. This avoids problems when using @code{cc -gl}
|
|
on @acronym{MIPS} machines. Previously, @code{step} entered subroutines if there
|
|
was any debugging information about the routine.
|
|
|
|
@item step @var{count}
|
|
Continue running as in @code{step}, but do so @var{count} times. If a
|
|
breakpoint is reached, or a signal not related to stepping occurs before
|
|
@var{count} steps, stepping stops right away.
|
|
|
|
@kindex next
|
|
@kindex n @r{(@code{next})}
|
|
@item next @r{[}@var{count}@r{]}
|
|
Continue to the next source line in the current (innermost) stack frame.
|
|
This is similar to @code{step}, but function calls that appear within
|
|
the line of code are executed without stopping. Execution stops when
|
|
control reaches a different line of code at the original stack level
|
|
that was executing when you gave the @code{next} command. This command
|
|
is abbreviated @code{n}.
|
|
|
|
An argument @var{count} is a repeat count, as for @code{step}.
|
|
|
|
|
|
@c FIX ME!! Do we delete this, or is there a way it fits in with
|
|
@c the following paragraph? --- Vctoria
|
|
@c
|
|
@c @code{next} within a function that lacks debugging information acts like
|
|
@c @code{step}, but any function calls appearing within the code of the
|
|
@c function are executed without stopping.
|
|
|
|
The @code{next} command only stops at the first instruction of a
|
|
source line. This prevents multiple stops that could otherwise occur in
|
|
@code{switch} statements, @code{for} loops, etc.
|
|
|
|
@kindex set step-mode
|
|
@item set step-mode
|
|
@cindex functions without line info, and stepping
|
|
@cindex stepping into functions with no line info
|
|
@itemx set step-mode on
|
|
The @code{set step-mode on} command causes the @code{step} command to
|
|
stop at the first instruction of a function which contains no debug line
|
|
information rather than stepping over it.
|
|
|
|
This is useful in cases where you may be interested in inspecting the
|
|
machine instructions of a function which has no symbolic info and do not
|
|
want @value{GDBN} to automatically skip over this function.
|
|
|
|
@item set step-mode off
|
|
Causes the @code{step} command to step over any functions which contains no
|
|
debug information. This is the default.
|
|
|
|
@item show step-mode
|
|
Show whether @value{GDBN} will stop in or step over functions without
|
|
source line debug information.
|
|
|
|
@kindex finish
|
|
@kindex fin @r{(@code{finish})}
|
|
@item finish
|
|
Continue running until just after function in the selected stack frame
|
|
returns. Print the returned value (if any). This command can be
|
|
abbreviated as @code{fin}.
|
|
|
|
Contrast this with the @code{return} command (@pxref{Returning,
|
|
,Returning from a Function}).
|
|
|
|
@kindex until
|
|
@kindex u @r{(@code{until})}
|
|
@cindex run until specified location
|
|
@item until
|
|
@itemx u
|
|
Continue running until a source line past the current line, in the
|
|
current stack frame, is reached. This command is used to avoid single
|
|
stepping through a loop more than once. It is like the @code{next}
|
|
command, except that when @code{until} encounters a jump, it
|
|
automatically continues execution until the program counter is greater
|
|
than the address of the jump.
|
|
|
|
This means that when you reach the end of a loop after single stepping
|
|
though it, @code{until} makes your program continue execution until it
|
|
exits the loop. In contrast, a @code{next} command at the end of a loop
|
|
simply steps back to the beginning of the loop, which forces you to step
|
|
through the next iteration.
|
|
|
|
@code{until} always stops your program if it attempts to exit the current
|
|
stack frame.
|
|
|
|
@code{until} may produce somewhat counterintuitive results if the order
|
|
of machine code does not match the order of the source lines. For
|
|
example, in the following excerpt from a debugging session, the @code{f}
|
|
(@code{frame}) command shows that execution is stopped at line
|
|
@code{206}; yet when we use @code{until}, we get to line @code{195}:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) f
|
|
#0 main (argc=4, argv=0xf7fffae8) at m4.c:206
|
|
206 expand_input();
|
|
(@value{GDBP}) until
|
|
195 for ( ; argc > 0; NEXTARG) @{
|
|
@end smallexample
|
|
|
|
This happened because, for execution efficiency, the compiler had
|
|
generated code for the loop closure test at the end, rather than the
|
|
start, of the loop---even though the test in a C @code{for}-loop is
|
|
written before the body of the loop. The @code{until} command appeared
|
|
to step back to the beginning of the loop when it advanced to this
|
|
expression; however, it has not really gone to an earlier
|
|
statement---not in terms of the actual machine code.
|
|
|
|
@code{until} with no argument works by means of single
|
|
instruction stepping, and hence is slower than @code{until} with an
|
|
argument.
|
|
|
|
@item until @var{location}
|
|
@itemx u @var{location}
|
|
Continue running your program until either the specified location is
|
|
reached, or the current stack frame returns. @var{location} is any of
|
|
the forms described in @ref{Specify Location}.
|
|
This form of the command uses temporary breakpoints, and
|
|
hence is quicker than @code{until} without an argument. The specified
|
|
location is actually reached only if it is in the current frame. This
|
|
implies that @code{until} can be used to skip over recursive function
|
|
invocations. For instance in the code below, if the current location is
|
|
line @code{96}, issuing @code{until 99} will execute the program up to
|
|
line @code{99} in the same invocation of factorial, i.e., after the inner
|
|
invocations have returned.
|
|
|
|
@smallexample
|
|
94 int factorial (int value)
|
|
95 @{
|
|
96 if (value > 1) @{
|
|
97 value *= factorial (value - 1);
|
|
98 @}
|
|
99 return (value);
|
|
100 @}
|
|
@end smallexample
|
|
|
|
|
|
@kindex advance @var{location}
|
|
@item advance @var{location}
|
|
Continue running the program up to the given @var{location}. An argument is
|
|
required, which should be of one of the forms described in
|
|
@ref{Specify Location}.
|
|
Execution will also stop upon exit from the current stack
|
|
frame. This command is similar to @code{until}, but @code{advance} will
|
|
not skip over recursive function calls, and the target location doesn't
|
|
have to be in the same frame as the current one.
|
|
|
|
|
|
@kindex stepi
|
|
@kindex si @r{(@code{stepi})}
|
|
@item stepi
|
|
@itemx stepi @var{arg}
|
|
@itemx si
|
|
Execute one machine instruction, then stop and return to the debugger.
|
|
|
|
It is often useful to do @samp{display/i $pc} when stepping by machine
|
|
instructions. This makes @value{GDBN} automatically display the next
|
|
instruction to be executed, each time your program stops. @xref{Auto
|
|
Display,, Automatic Display}.
|
|
|
|
An argument is a repeat count, as in @code{step}.
|
|
|
|
@need 750
|
|
@kindex nexti
|
|
@kindex ni @r{(@code{nexti})}
|
|
@item nexti
|
|
@itemx nexti @var{arg}
|
|
@itemx ni
|
|
Execute one machine instruction, but if it is a function call,
|
|
proceed until the function returns.
|
|
|
|
An argument is a repeat count, as in @code{next}.
|
|
@end table
|
|
|
|
@node Skipping Over Functions and Files
|
|
@section Skipping Over Functions and Files
|
|
@cindex skipping over functions and files
|
|
|
|
The program you are debugging may contain some functions which are
|
|
uninteresting to debug. The @code{skip} comand lets you tell @value{GDBN} to
|
|
skip a function or all functions in a file when stepping.
|
|
|
|
For example, consider the following C function:
|
|
|
|
@smallexample
|
|
101 int func()
|
|
102 @{
|
|
103 foo(boring());
|
|
104 bar(boring());
|
|
105 @}
|
|
@end smallexample
|
|
|
|
@noindent
|
|
Suppose you wish to step into the functions @code{foo} and @code{bar}, but you
|
|
are not interested in stepping through @code{boring}. If you run @code{step}
|
|
at line 103, you'll enter @code{boring()}, but if you run @code{next}, you'll
|
|
step over both @code{foo} and @code{boring}!
|
|
|
|
One solution is to @code{step} into @code{boring} and use the @code{finish}
|
|
command to immediately exit it. But this can become tedious if @code{boring}
|
|
is called from many places.
|
|
|
|
A more flexible solution is to execute @kbd{skip boring}. This instructs
|
|
@value{GDBN} never to step into @code{boring}. Now when you execute
|
|
@code{step} at line 103, you'll step over @code{boring} and directly into
|
|
@code{foo}.
|
|
|
|
You can also instruct @value{GDBN} to skip all functions in a file, with, for
|
|
example, @code{skip file boring.c}.
|
|
|
|
@table @code
|
|
@kindex skip function
|
|
@item skip @r{[}@var{linespec}@r{]}
|
|
@itemx skip function @r{[}@var{linespec}@r{]}
|
|
After running this command, the function named by @var{linespec} or the
|
|
function containing the line named by @var{linespec} will be skipped over when
|
|
stepping. @xref{Specify Location}.
|
|
|
|
If you do not specify @var{linespec}, the function you're currently debugging
|
|
will be skipped.
|
|
|
|
(If you have a function called @code{file} that you want to skip, use
|
|
@kbd{skip function file}.)
|
|
|
|
@kindex skip file
|
|
@item skip file @r{[}@var{filename}@r{]}
|
|
After running this command, any function whose source lives in @var{filename}
|
|
will be skipped over when stepping.
|
|
|
|
If you do not specify @var{filename}, functions whose source lives in the file
|
|
you're currently debugging will be skipped.
|
|
@end table
|
|
|
|
Skips can be listed, deleted, disabled, and enabled, much like breakpoints.
|
|
These are the commands for managing your list of skips:
|
|
|
|
@table @code
|
|
@kindex info skip
|
|
@item info skip @r{[}@var{range}@r{]}
|
|
Print details about the specified skip(s). If @var{range} is not specified,
|
|
print a table with details about all functions and files marked for skipping.
|
|
@code{info skip} prints the following information about each skip:
|
|
|
|
@table @emph
|
|
@item Identifier
|
|
A number identifying this skip.
|
|
@item Type
|
|
The type of this skip, either @samp{function} or @samp{file}.
|
|
@item Enabled or Disabled
|
|
Enabled skips are marked with @samp{y}. Disabled skips are marked with @samp{n}.
|
|
@item Address
|
|
For function skips, this column indicates the address in memory of the function
|
|
being skipped. If you've set a function skip on a function which has not yet
|
|
been loaded, this field will contain @samp{<PENDING>}. Once a shared library
|
|
which has the function is loaded, @code{info skip} will show the function's
|
|
address here.
|
|
@item What
|
|
For file skips, this field contains the filename being skipped. For functions
|
|
skips, this field contains the function name and its line number in the file
|
|
where it is defined.
|
|
@end table
|
|
|
|
@kindex skip delete
|
|
@item skip delete @r{[}@var{range}@r{]}
|
|
Delete the specified skip(s). If @var{range} is not specified, delete all
|
|
skips.
|
|
|
|
@kindex skip enable
|
|
@item skip enable @r{[}@var{range}@r{]}
|
|
Enable the specified skip(s). If @var{range} is not specified, enable all
|
|
skips.
|
|
|
|
@kindex skip disable
|
|
@item skip disable @r{[}@var{range}@r{]}
|
|
Disable the specified skip(s). If @var{range} is not specified, disable all
|
|
skips.
|
|
|
|
@end table
|
|
|
|
@node Signals
|
|
@section Signals
|
|
@cindex signals
|
|
|
|
A signal is an asynchronous event that can happen in a program. The
|
|
operating system defines the possible kinds of signals, and gives each
|
|
kind a name and a number. For example, in Unix @code{SIGINT} is the
|
|
signal a program gets when you type an interrupt character (often @kbd{Ctrl-c});
|
|
@code{SIGSEGV} is the signal a program gets from referencing a place in
|
|
memory far away from all the areas in use; @code{SIGALRM} occurs when
|
|
the alarm clock timer goes off (which happens only if your program has
|
|
requested an alarm).
|
|
|
|
@cindex fatal signals
|
|
Some signals, including @code{SIGALRM}, are a normal part of the
|
|
functioning of your program. Others, such as @code{SIGSEGV}, indicate
|
|
errors; these signals are @dfn{fatal} (they kill your program immediately) if the
|
|
program has not specified in advance some other way to handle the signal.
|
|
@code{SIGINT} does not indicate an error in your program, but it is normally
|
|
fatal so it can carry out the purpose of the interrupt: to kill the program.
|
|
|
|
@value{GDBN} has the ability to detect any occurrence of a signal in your
|
|
program. You can tell @value{GDBN} in advance what to do for each kind of
|
|
signal.
|
|
|
|
@cindex handling signals
|
|
Normally, @value{GDBN} is set up to let the non-erroneous signals like
|
|
@code{SIGALRM} be silently passed to your program
|
|
(so as not to interfere with their role in the program's functioning)
|
|
but to stop your program immediately whenever an error signal happens.
|
|
You can change these settings with the @code{handle} command.
|
|
|
|
@table @code
|
|
@kindex info signals
|
|
@kindex info handle
|
|
@item info signals
|
|
@itemx info handle
|
|
Print a table of all the kinds of signals and how @value{GDBN} has been told to
|
|
handle each one. You can use this to see the signal numbers of all
|
|
the defined types of signals.
|
|
|
|
@item info signals @var{sig}
|
|
Similar, but print information only about the specified signal number.
|
|
|
|
@code{info handle} is an alias for @code{info signals}.
|
|
|
|
@kindex handle
|
|
@item handle @var{signal} @r{[}@var{keywords}@dots{}@r{]}
|
|
Change the way @value{GDBN} handles signal @var{signal}. @var{signal}
|
|
can be the number of a signal or its name (with or without the
|
|
@samp{SIG} at the beginning); a list of signal numbers of the form
|
|
@samp{@var{low}-@var{high}}; or the word @samp{all}, meaning all the
|
|
known signals. Optional arguments @var{keywords}, described below,
|
|
say what change to make.
|
|
@end table
|
|
|
|
@c @group
|
|
The keywords allowed by the @code{handle} command can be abbreviated.
|
|
Their full names are:
|
|
|
|
@table @code
|
|
@item nostop
|
|
@value{GDBN} should not stop your program when this signal happens. It may
|
|
still print a message telling you that the signal has come in.
|
|
|
|
@item stop
|
|
@value{GDBN} should stop your program when this signal happens. This implies
|
|
the @code{print} keyword as well.
|
|
|
|
@item print
|
|
@value{GDBN} should print a message when this signal happens.
|
|
|
|
@item noprint
|
|
@value{GDBN} should not mention the occurrence of the signal at all. This
|
|
implies the @code{nostop} keyword as well.
|
|
|
|
@item pass
|
|
@itemx noignore
|
|
@value{GDBN} should allow your program to see this signal; your program
|
|
can handle the signal, or else it may terminate if the signal is fatal
|
|
and not handled. @code{pass} and @code{noignore} are synonyms.
|
|
|
|
@item nopass
|
|
@itemx ignore
|
|
@value{GDBN} should not allow your program to see this signal.
|
|
@code{nopass} and @code{ignore} are synonyms.
|
|
@end table
|
|
@c @end group
|
|
|
|
When a signal stops your program, the signal is not visible to the
|
|
program until you
|
|
continue. Your program sees the signal then, if @code{pass} is in
|
|
effect for the signal in question @emph{at that time}. In other words,
|
|
after @value{GDBN} reports a signal, you can use the @code{handle}
|
|
command with @code{pass} or @code{nopass} to control whether your
|
|
program sees that signal when you continue.
|
|
|
|
The default is set to @code{nostop}, @code{noprint}, @code{pass} for
|
|
non-erroneous signals such as @code{SIGALRM}, @code{SIGWINCH} and
|
|
@code{SIGCHLD}, and to @code{stop}, @code{print}, @code{pass} for the
|
|
erroneous signals.
|
|
|
|
You can also use the @code{signal} command to prevent your program from
|
|
seeing a signal, or cause it to see a signal it normally would not see,
|
|
or to give it any signal at any time. For example, if your program stopped
|
|
due to some sort of memory reference error, you might store correct
|
|
values into the erroneous variables and continue, hoping to see more
|
|
execution; but your program would probably terminate immediately as
|
|
a result of the fatal signal once it saw the signal. To prevent this,
|
|
you can continue with @samp{signal 0}. @xref{Signaling, ,Giving your
|
|
Program a Signal}.
|
|
|
|
@cindex extra signal information
|
|
@anchor{extra signal information}
|
|
|
|
On some targets, @value{GDBN} can inspect extra signal information
|
|
associated with the intercepted signal, before it is actually
|
|
delivered to the program being debugged. This information is exported
|
|
by the convenience variable @code{$_siginfo}, and consists of data
|
|
that is passed by the kernel to the signal handler at the time of the
|
|
receipt of a signal. The data type of the information itself is
|
|
target dependent. You can see the data type using the @code{ptype
|
|
$_siginfo} command. On Unix systems, it typically corresponds to the
|
|
standard @code{siginfo_t} type, as defined in the @file{signal.h}
|
|
system header.
|
|
|
|
Here's an example, on a @sc{gnu}/Linux system, printing the stray
|
|
referenced address that raised a segmentation fault.
|
|
|
|
@smallexample
|
|
@group
|
|
(@value{GDBP}) continue
|
|
Program received signal SIGSEGV, Segmentation fault.
|
|
0x0000000000400766 in main ()
|
|
69 *(int *)p = 0;
|
|
(@value{GDBP}) ptype $_siginfo
|
|
type = struct @{
|
|
int si_signo;
|
|
int si_errno;
|
|
int si_code;
|
|
union @{
|
|
int _pad[28];
|
|
struct @{...@} _kill;
|
|
struct @{...@} _timer;
|
|
struct @{...@} _rt;
|
|
struct @{...@} _sigchld;
|
|
struct @{...@} _sigfault;
|
|
struct @{...@} _sigpoll;
|
|
@} _sifields;
|
|
@}
|
|
(@value{GDBP}) ptype $_siginfo._sifields._sigfault
|
|
type = struct @{
|
|
void *si_addr;
|
|
@}
|
|
(@value{GDBP}) p $_siginfo._sifields._sigfault.si_addr
|
|
$1 = (void *) 0x7ffff7ff7000
|
|
@end group
|
|
@end smallexample
|
|
|
|
Depending on target support, @code{$_siginfo} may also be writable.
|
|
|
|
@node Thread Stops
|
|
@section Stopping and Starting Multi-thread Programs
|
|
|
|
@cindex stopped threads
|
|
@cindex threads, stopped
|
|
|
|
@cindex continuing threads
|
|
@cindex threads, continuing
|
|
|
|
@value{GDBN} supports debugging programs with multiple threads
|
|
(@pxref{Threads,, Debugging Programs with Multiple Threads}). There
|
|
are two modes of controlling execution of your program within the
|
|
debugger. In the default mode, referred to as @dfn{all-stop mode},
|
|
when any thread in your program stops (for example, at a breakpoint
|
|
or while being stepped), all other threads in the program are also stopped by
|
|
@value{GDBN}. On some targets, @value{GDBN} also supports
|
|
@dfn{non-stop mode}, in which other threads can continue to run freely while
|
|
you examine the stopped thread in the debugger.
|
|
|
|
@menu
|
|
* All-Stop Mode:: All threads stop when GDB takes control
|
|
* Non-Stop Mode:: Other threads continue to execute
|
|
* Background Execution:: Running your program asynchronously
|
|
* Thread-Specific Breakpoints:: Controlling breakpoints
|
|
* Interrupted System Calls:: GDB may interfere with system calls
|
|
* Observer Mode:: GDB does not alter program behavior
|
|
@end menu
|
|
|
|
@node All-Stop Mode
|
|
@subsection All-Stop Mode
|
|
|
|
@cindex all-stop mode
|
|
|
|
In all-stop mode, whenever your program stops under @value{GDBN} for any reason,
|
|
@emph{all} threads of execution stop, not just the current thread. This
|
|
allows you to examine the overall state of the program, including
|
|
switching between threads, without worrying that things may change
|
|
underfoot.
|
|
|
|
Conversely, whenever you restart the program, @emph{all} threads start
|
|
executing. @emph{This is true even when single-stepping} with commands
|
|
like @code{step} or @code{next}.
|
|
|
|
In particular, @value{GDBN} cannot single-step all threads in lockstep.
|
|
Since thread scheduling is up to your debugging target's operating
|
|
system (not controlled by @value{GDBN}), other threads may
|
|
execute more than one statement while the current thread completes a
|
|
single step. Moreover, in general other threads stop in the middle of a
|
|
statement, rather than at a clean statement boundary, when the program
|
|
stops.
|
|
|
|
You might even find your program stopped in another thread after
|
|
continuing or even single-stepping. This happens whenever some other
|
|
thread runs into a breakpoint, a signal, or an exception before the
|
|
first thread completes whatever you requested.
|
|
|
|
@cindex automatic thread selection
|
|
@cindex switching threads automatically
|
|
@cindex threads, automatic switching
|
|
Whenever @value{GDBN} stops your program, due to a breakpoint or a
|
|
signal, it automatically selects the thread where that breakpoint or
|
|
signal happened. @value{GDBN} alerts you to the context switch with a
|
|
message such as @samp{[Switching to Thread @var{n}]} to identify the
|
|
thread.
|
|
|
|
On some OSes, you can modify @value{GDBN}'s default behavior by
|
|
locking the OS scheduler to allow only a single thread to run.
|
|
|
|
@table @code
|
|
@item set scheduler-locking @var{mode}
|
|
@cindex scheduler locking mode
|
|
@cindex lock scheduler
|
|
Set the scheduler locking mode. If it is @code{off}, then there is no
|
|
locking and any thread may run at any time. If @code{on}, then only the
|
|
current thread may run when the inferior is resumed. The @code{step}
|
|
mode optimizes for single-stepping; it prevents other threads
|
|
from preempting the current thread while you are stepping, so that
|
|
the focus of debugging does not change unexpectedly.
|
|
Other threads only rarely (or never) get a chance to run
|
|
when you step. They are more likely to run when you @samp{next} over a
|
|
function call, and they are completely free to run when you use commands
|
|
like @samp{continue}, @samp{until}, or @samp{finish}. However, unless another
|
|
thread hits a breakpoint during its timeslice, @value{GDBN} does not change
|
|
the current thread away from the thread that you are debugging.
|
|
|
|
@item show scheduler-locking
|
|
Display the current scheduler locking mode.
|
|
@end table
|
|
|
|
@cindex resume threads of multiple processes simultaneously
|
|
By default, when you issue one of the execution commands such as
|
|
@code{continue}, @code{next} or @code{step}, @value{GDBN} allows only
|
|
threads of the current inferior to run. For example, if @value{GDBN}
|
|
is attached to two inferiors, each with two threads, the
|
|
@code{continue} command resumes only the two threads of the current
|
|
inferior. This is useful, for example, when you debug a program that
|
|
forks and you want to hold the parent stopped (so that, for instance,
|
|
it doesn't run to exit), while you debug the child. In other
|
|
situations, you may not be interested in inspecting the current state
|
|
of any of the processes @value{GDBN} is attached to, and you may want
|
|
to resume them all until some breakpoint is hit. In the latter case,
|
|
you can instruct @value{GDBN} to allow all threads of all the
|
|
inferiors to run with the @w{@code{set schedule-multiple}} command.
|
|
|
|
@table @code
|
|
@kindex set schedule-multiple
|
|
@item set schedule-multiple
|
|
Set the mode for allowing threads of multiple processes to be resumed
|
|
when an execution command is issued. When @code{on}, all threads of
|
|
all processes are allowed to run. When @code{off}, only the threads
|
|
of the current process are resumed. The default is @code{off}. The
|
|
@code{scheduler-locking} mode takes precedence when set to @code{on},
|
|
or while you are stepping and set to @code{step}.
|
|
|
|
@item show schedule-multiple
|
|
Display the current mode for resuming the execution of threads of
|
|
multiple processes.
|
|
@end table
|
|
|
|
@node Non-Stop Mode
|
|
@subsection Non-Stop Mode
|
|
|
|
@cindex non-stop mode
|
|
|
|
@c This section is really only a place-holder, and needs to be expanded
|
|
@c with more details.
|
|
|
|
For some multi-threaded targets, @value{GDBN} supports an optional
|
|
mode of operation in which you can examine stopped program threads in
|
|
the debugger while other threads continue to execute freely. This
|
|
minimizes intrusion when debugging live systems, such as programs
|
|
where some threads have real-time constraints or must continue to
|
|
respond to external events. This is referred to as @dfn{non-stop} mode.
|
|
|
|
In non-stop mode, when a thread stops to report a debugging event,
|
|
@emph{only} that thread is stopped; @value{GDBN} does not stop other
|
|
threads as well, in contrast to the all-stop mode behavior. Additionally,
|
|
execution commands such as @code{continue} and @code{step} apply by default
|
|
only to the current thread in non-stop mode, rather than all threads as
|
|
in all-stop mode. This allows you to control threads explicitly in
|
|
ways that are not possible in all-stop mode --- for example, stepping
|
|
one thread while allowing others to run freely, stepping
|
|
one thread while holding all others stopped, or stepping several threads
|
|
independently and simultaneously.
|
|
|
|
To enter non-stop mode, use this sequence of commands before you run
|
|
or attach to your program:
|
|
|
|
@smallexample
|
|
# Enable the async interface.
|
|
set target-async 1
|
|
|
|
# If using the CLI, pagination breaks non-stop.
|
|
set pagination off
|
|
|
|
# Finally, turn it on!
|
|
set non-stop on
|
|
@end smallexample
|
|
|
|
You can use these commands to manipulate the non-stop mode setting:
|
|
|
|
@table @code
|
|
@kindex set non-stop
|
|
@item set non-stop on
|
|
Enable selection of non-stop mode.
|
|
@item set non-stop off
|
|
Disable selection of non-stop mode.
|
|
@kindex show non-stop
|
|
@item show non-stop
|
|
Show the current non-stop enablement setting.
|
|
@end table
|
|
|
|
Note these commands only reflect whether non-stop mode is enabled,
|
|
not whether the currently-executing program is being run in non-stop mode.
|
|
In particular, the @code{set non-stop} preference is only consulted when
|
|
@value{GDBN} starts or connects to the target program, and it is generally
|
|
not possible to switch modes once debugging has started. Furthermore,
|
|
since not all targets support non-stop mode, even when you have enabled
|
|
non-stop mode, @value{GDBN} may still fall back to all-stop operation by
|
|
default.
|
|
|
|
In non-stop mode, all execution commands apply only to the current thread
|
|
by default. That is, @code{continue} only continues one thread.
|
|
To continue all threads, issue @code{continue -a} or @code{c -a}.
|
|
|
|
You can use @value{GDBN}'s background execution commands
|
|
(@pxref{Background Execution}) to run some threads in the background
|
|
while you continue to examine or step others from @value{GDBN}.
|
|
The MI execution commands (@pxref{GDB/MI Program Execution}) are
|
|
always executed asynchronously in non-stop mode.
|
|
|
|
Suspending execution is done with the @code{interrupt} command when
|
|
running in the background, or @kbd{Ctrl-c} during foreground execution.
|
|
In all-stop mode, this stops the whole process;
|
|
but in non-stop mode the interrupt applies only to the current thread.
|
|
To stop the whole program, use @code{interrupt -a}.
|
|
|
|
Other execution commands do not currently support the @code{-a} option.
|
|
|
|
In non-stop mode, when a thread stops, @value{GDBN} doesn't automatically make
|
|
that thread current, as it does in all-stop mode. This is because the
|
|
thread stop notifications are asynchronous with respect to @value{GDBN}'s
|
|
command interpreter, and it would be confusing if @value{GDBN} unexpectedly
|
|
changed to a different thread just as you entered a command to operate on the
|
|
previously current thread.
|
|
|
|
@node Background Execution
|
|
@subsection Background Execution
|
|
|
|
@cindex foreground execution
|
|
@cindex background execution
|
|
@cindex asynchronous execution
|
|
@cindex execution, foreground, background and asynchronous
|
|
|
|
@value{GDBN}'s execution commands have two variants: the normal
|
|
foreground (synchronous) behavior, and a background
|
|
(asynchronous) behavior. In foreground execution, @value{GDBN} waits for
|
|
the program to report that some thread has stopped before prompting for
|
|
another command. In background execution, @value{GDBN} immediately gives
|
|
a command prompt so that you can issue other commands while your program runs.
|
|
|
|
You need to explicitly enable asynchronous mode before you can use
|
|
background execution commands. You can use these commands to
|
|
manipulate the asynchronous mode setting:
|
|
|
|
@table @code
|
|
@kindex set target-async
|
|
@item set target-async on
|
|
Enable asynchronous mode.
|
|
@item set target-async off
|
|
Disable asynchronous mode.
|
|
@kindex show target-async
|
|
@item show target-async
|
|
Show the current target-async setting.
|
|
@end table
|
|
|
|
If the target doesn't support async mode, @value{GDBN} issues an error
|
|
message if you attempt to use the background execution commands.
|
|
|
|
To specify background execution, add a @code{&} to the command. For example,
|
|
the background form of the @code{continue} command is @code{continue&}, or
|
|
just @code{c&}. The execution commands that accept background execution
|
|
are:
|
|
|
|
@table @code
|
|
@kindex run&
|
|
@item run
|
|
@xref{Starting, , Starting your Program}.
|
|
|
|
@item attach
|
|
@kindex attach&
|
|
@xref{Attach, , Debugging an Already-running Process}.
|
|
|
|
@item step
|
|
@kindex step&
|
|
@xref{Continuing and Stepping, step}.
|
|
|
|
@item stepi
|
|
@kindex stepi&
|
|
@xref{Continuing and Stepping, stepi}.
|
|
|
|
@item next
|
|
@kindex next&
|
|
@xref{Continuing and Stepping, next}.
|
|
|
|
@item nexti
|
|
@kindex nexti&
|
|
@xref{Continuing and Stepping, nexti}.
|
|
|
|
@item continue
|
|
@kindex continue&
|
|
@xref{Continuing and Stepping, continue}.
|
|
|
|
@item finish
|
|
@kindex finish&
|
|
@xref{Continuing and Stepping, finish}.
|
|
|
|
@item until
|
|
@kindex until&
|
|
@xref{Continuing and Stepping, until}.
|
|
|
|
@end table
|
|
|
|
Background execution is especially useful in conjunction with non-stop
|
|
mode for debugging programs with multiple threads; see @ref{Non-Stop Mode}.
|
|
However, you can also use these commands in the normal all-stop mode with
|
|
the restriction that you cannot issue another execution command until the
|
|
previous one finishes. Examples of commands that are valid in all-stop
|
|
mode while the program is running include @code{help} and @code{info break}.
|
|
|
|
You can interrupt your program while it is running in the background by
|
|
using the @code{interrupt} command.
|
|
|
|
@table @code
|
|
@kindex interrupt
|
|
@item interrupt
|
|
@itemx interrupt -a
|
|
|
|
Suspend execution of the running program. In all-stop mode,
|
|
@code{interrupt} stops the whole process, but in non-stop mode, it stops
|
|
only the current thread. To stop the whole program in non-stop mode,
|
|
use @code{interrupt -a}.
|
|
@end table
|
|
|
|
@node Thread-Specific Breakpoints
|
|
@subsection Thread-Specific Breakpoints
|
|
|
|
When your program has multiple threads (@pxref{Threads,, Debugging
|
|
Programs with Multiple Threads}), you can choose whether to set
|
|
breakpoints on all threads, or on a particular thread.
|
|
|
|
@table @code
|
|
@cindex breakpoints and threads
|
|
@cindex thread breakpoints
|
|
@kindex break @dots{} thread @var{threadno}
|
|
@item break @var{linespec} thread @var{threadno}
|
|
@itemx break @var{linespec} thread @var{threadno} if @dots{}
|
|
@var{linespec} specifies source lines; there are several ways of
|
|
writing them (@pxref{Specify Location}), but the effect is always to
|
|
specify some source line.
|
|
|
|
Use the qualifier @samp{thread @var{threadno}} with a breakpoint command
|
|
to specify that you only want @value{GDBN} to stop the program when a
|
|
particular thread reaches this breakpoint. @var{threadno} is one of the
|
|
numeric thread identifiers assigned by @value{GDBN}, shown in the first
|
|
column of the @samp{info threads} display.
|
|
|
|
If you do not specify @samp{thread @var{threadno}} when you set a
|
|
breakpoint, the breakpoint applies to @emph{all} threads of your
|
|
program.
|
|
|
|
You can use the @code{thread} qualifier on conditional breakpoints as
|
|
well; in this case, place @samp{thread @var{threadno}} before or
|
|
after the breakpoint condition, like this:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) break frik.c:13 thread 28 if bartab > lim
|
|
@end smallexample
|
|
|
|
@end table
|
|
|
|
@node Interrupted System Calls
|
|
@subsection Interrupted System Calls
|
|
|
|
@cindex thread breakpoints and system calls
|
|
@cindex system calls and thread breakpoints
|
|
@cindex premature return from system calls
|
|
There is an unfortunate side effect when using @value{GDBN} to debug
|
|
multi-threaded programs. If one thread stops for a
|
|
breakpoint, or for some other reason, and another thread is blocked in a
|
|
system call, then the system call may return prematurely. This is a
|
|
consequence of the interaction between multiple threads and the signals
|
|
that @value{GDBN} uses to implement breakpoints and other events that
|
|
stop execution.
|
|
|
|
To handle this problem, your program should check the return value of
|
|
each system call and react appropriately. This is good programming
|
|
style anyways.
|
|
|
|
For example, do not write code like this:
|
|
|
|
@smallexample
|
|
sleep (10);
|
|
@end smallexample
|
|
|
|
The call to @code{sleep} will return early if a different thread stops
|
|
at a breakpoint or for some other reason.
|
|
|
|
Instead, write this:
|
|
|
|
@smallexample
|
|
int unslept = 10;
|
|
while (unslept > 0)
|
|
unslept = sleep (unslept);
|
|
@end smallexample
|
|
|
|
A system call is allowed to return early, so the system is still
|
|
conforming to its specification. But @value{GDBN} does cause your
|
|
multi-threaded program to behave differently than it would without
|
|
@value{GDBN}.
|
|
|
|
Also, @value{GDBN} uses internal breakpoints in the thread library to
|
|
monitor certain events such as thread creation and thread destruction.
|
|
When such an event happens, a system call in another thread may return
|
|
prematurely, even though your program does not appear to stop.
|
|
|
|
@node Observer Mode
|
|
@subsection Observer Mode
|
|
|
|
If you want to build on non-stop mode and observe program behavior
|
|
without any chance of disruption by @value{GDBN}, you can set
|
|
variables to disable all of the debugger's attempts to modify state,
|
|
whether by writing memory, inserting breakpoints, etc. These operate
|
|
at a low level, intercepting operations from all commands.
|
|
|
|
When all of these are set to @code{off}, then @value{GDBN} is said to
|
|
be @dfn{observer mode}. As a convenience, the variable
|
|
@code{observer} can be set to disable these, plus enable non-stop
|
|
mode.
|
|
|
|
Note that @value{GDBN} will not prevent you from making nonsensical
|
|
combinations of these settings. For instance, if you have enabled
|
|
@code{may-insert-breakpoints} but disabled @code{may-write-memory},
|
|
then breakpoints that work by writing trap instructions into the code
|
|
stream will still not be able to be placed.
|
|
|
|
@table @code
|
|
|
|
@kindex observer
|
|
@item set observer on
|
|
@itemx set observer off
|
|
When set to @code{on}, this disables all the permission variables
|
|
below (except for @code{insert-fast-tracepoints}), plus enables
|
|
non-stop debugging. Setting this to @code{off} switches back to
|
|
normal debugging, though remaining in non-stop mode.
|
|
|
|
@item show observer
|
|
Show whether observer mode is on or off.
|
|
|
|
@kindex may-write-registers
|
|
@item set may-write-registers on
|
|
@itemx set may-write-registers off
|
|
This controls whether @value{GDBN} will attempt to alter the values of
|
|
registers, such as with assignment expressions in @code{print}, or the
|
|
@code{jump} command. It defaults to @code{on}.
|
|
|
|
@item show may-write-registers
|
|
Show the current permission to write registers.
|
|
|
|
@kindex may-write-memory
|
|
@item set may-write-memory on
|
|
@itemx set may-write-memory off
|
|
This controls whether @value{GDBN} will attempt to alter the contents
|
|
of memory, such as with assignment expressions in @code{print}. It
|
|
defaults to @code{on}.
|
|
|
|
@item show may-write-memory
|
|
Show the current permission to write memory.
|
|
|
|
@kindex may-insert-breakpoints
|
|
@item set may-insert-breakpoints on
|
|
@itemx set may-insert-breakpoints off
|
|
This controls whether @value{GDBN} will attempt to insert breakpoints.
|
|
This affects all breakpoints, including internal breakpoints defined
|
|
by @value{GDBN}. It defaults to @code{on}.
|
|
|
|
@item show may-insert-breakpoints
|
|
Show the current permission to insert breakpoints.
|
|
|
|
@kindex may-insert-tracepoints
|
|
@item set may-insert-tracepoints on
|
|
@itemx set may-insert-tracepoints off
|
|
This controls whether @value{GDBN} will attempt to insert (regular)
|
|
tracepoints at the beginning of a tracing experiment. It affects only
|
|
non-fast tracepoints, fast tracepoints being under the control of
|
|
@code{may-insert-fast-tracepoints}. It defaults to @code{on}.
|
|
|
|
@item show may-insert-tracepoints
|
|
Show the current permission to insert tracepoints.
|
|
|
|
@kindex may-insert-fast-tracepoints
|
|
@item set may-insert-fast-tracepoints on
|
|
@itemx set may-insert-fast-tracepoints off
|
|
This controls whether @value{GDBN} will attempt to insert fast
|
|
tracepoints at the beginning of a tracing experiment. It affects only
|
|
fast tracepoints, regular (non-fast) tracepoints being under the
|
|
control of @code{may-insert-tracepoints}. It defaults to @code{on}.
|
|
|
|
@item show may-insert-fast-tracepoints
|
|
Show the current permission to insert fast tracepoints.
|
|
|
|
@kindex may-interrupt
|
|
@item set may-interrupt on
|
|
@itemx set may-interrupt off
|
|
This controls whether @value{GDBN} will attempt to interrupt or stop
|
|
program execution. When this variable is @code{off}, the
|
|
@code{interrupt} command will have no effect, nor will
|
|
@kbd{Ctrl-c}. It defaults to @code{on}.
|
|
|
|
@item show may-interrupt
|
|
Show the current permission to interrupt or stop the program.
|
|
|
|
@end table
|
|
|
|
@node Reverse Execution
|
|
@chapter Running programs backward
|
|
@cindex reverse execution
|
|
@cindex running programs backward
|
|
|
|
When you are debugging a program, it is not unusual to realize that
|
|
you have gone too far, and some event of interest has already happened.
|
|
If the target environment supports it, @value{GDBN} can allow you to
|
|
``rewind'' the program by running it backward.
|
|
|
|
A target environment that supports reverse execution should be able
|
|
to ``undo'' the changes in machine state that have taken place as the
|
|
program was executing normally. Variables, registers etc.@: should
|
|
revert to their previous values. Obviously this requires a great
|
|
deal of sophistication on the part of the target environment; not
|
|
all target environments can support reverse execution.
|
|
|
|
When a program is executed in reverse, the instructions that
|
|
have most recently been executed are ``un-executed'', in reverse
|
|
order. The program counter runs backward, following the previous
|
|
thread of execution in reverse. As each instruction is ``un-executed'',
|
|
the values of memory and/or registers that were changed by that
|
|
instruction are reverted to their previous states. After executing
|
|
a piece of source code in reverse, all side effects of that code
|
|
should be ``undone'', and all variables should be returned to their
|
|
prior values@footnote{
|
|
Note that some side effects are easier to undo than others. For instance,
|
|
memory and registers are relatively easy, but device I/O is hard. Some
|
|
targets may be able undo things like device I/O, and some may not.
|
|
|
|
The contract between @value{GDBN} and the reverse executing target
|
|
requires only that the target do something reasonable when
|
|
@value{GDBN} tells it to execute backwards, and then report the
|
|
results back to @value{GDBN}. Whatever the target reports back to
|
|
@value{GDBN}, @value{GDBN} will report back to the user. @value{GDBN}
|
|
assumes that the memory and registers that the target reports are in a
|
|
consistant state, but @value{GDBN} accepts whatever it is given.
|
|
}.
|
|
|
|
If you are debugging in a target environment that supports
|
|
reverse execution, @value{GDBN} provides the following commands.
|
|
|
|
@table @code
|
|
@kindex reverse-continue
|
|
@kindex rc @r{(@code{reverse-continue})}
|
|
@item reverse-continue @r{[}@var{ignore-count}@r{]}
|
|
@itemx rc @r{[}@var{ignore-count}@r{]}
|
|
Beginning at the point where your program last stopped, start executing
|
|
in reverse. Reverse execution will stop for breakpoints and synchronous
|
|
exceptions (signals), just like normal execution. Behavior of
|
|
asynchronous signals depends on the target environment.
|
|
|
|
@kindex reverse-step
|
|
@kindex rs @r{(@code{step})}
|
|
@item reverse-step @r{[}@var{count}@r{]}
|
|
Run the program backward until control reaches the start of a
|
|
different source line; then stop it, and return control to @value{GDBN}.
|
|
|
|
Like the @code{step} command, @code{reverse-step} will only stop
|
|
at the beginning of a source line. It ``un-executes'' the previously
|
|
executed source line. If the previous source line included calls to
|
|
debuggable functions, @code{reverse-step} will step (backward) into
|
|
the called function, stopping at the beginning of the @emph{last}
|
|
statement in the called function (typically a return statement).
|
|
|
|
Also, as with the @code{step} command, if non-debuggable functions are
|
|
called, @code{reverse-step} will run thru them backward without stopping.
|
|
|
|
@kindex reverse-stepi
|
|
@kindex rsi @r{(@code{reverse-stepi})}
|
|
@item reverse-stepi @r{[}@var{count}@r{]}
|
|
Reverse-execute one machine instruction. Note that the instruction
|
|
to be reverse-executed is @emph{not} the one pointed to by the program
|
|
counter, but the instruction executed prior to that one. For instance,
|
|
if the last instruction was a jump, @code{reverse-stepi} will take you
|
|
back from the destination of the jump to the jump instruction itself.
|
|
|
|
@kindex reverse-next
|
|
@kindex rn @r{(@code{reverse-next})}
|
|
@item reverse-next @r{[}@var{count}@r{]}
|
|
Run backward to the beginning of the previous line executed in
|
|
the current (innermost) stack frame. If the line contains function
|
|
calls, they will be ``un-executed'' without stopping. Starting from
|
|
the first line of a function, @code{reverse-next} will take you back
|
|
to the caller of that function, @emph{before} the function was called,
|
|
just as the normal @code{next} command would take you from the last
|
|
line of a function back to its return to its caller
|
|
@footnote{Unless the code is too heavily optimized.}.
|
|
|
|
@kindex reverse-nexti
|
|
@kindex rni @r{(@code{reverse-nexti})}
|
|
@item reverse-nexti @r{[}@var{count}@r{]}
|
|
Like @code{nexti}, @code{reverse-nexti} executes a single instruction
|
|
in reverse, except that called functions are ``un-executed'' atomically.
|
|
That is, if the previously executed instruction was a return from
|
|
another function, @code{reverse-nexti} will continue to execute
|
|
in reverse until the call to that function (from the current stack
|
|
frame) is reached.
|
|
|
|
@kindex reverse-finish
|
|
@item reverse-finish
|
|
Just as the @code{finish} command takes you to the point where the
|
|
current function returns, @code{reverse-finish} takes you to the point
|
|
where it was called. Instead of ending up at the end of the current
|
|
function invocation, you end up at the beginning.
|
|
|
|
@kindex set exec-direction
|
|
@item set exec-direction
|
|
Set the direction of target execution.
|
|
@item set exec-direction reverse
|
|
@cindex execute forward or backward in time
|
|
@value{GDBN} will perform all execution commands in reverse, until the
|
|
exec-direction mode is changed to ``forward''. Affected commands include
|
|
@code{step, stepi, next, nexti, continue, and finish}. The @code{return}
|
|
command cannot be used in reverse mode.
|
|
@item set exec-direction forward
|
|
@value{GDBN} will perform all execution commands in the normal fashion.
|
|
This is the default.
|
|
@end table
|
|
|
|
|
|
@node Process Record and Replay
|
|
@chapter Recording Inferior's Execution and Replaying It
|
|
@cindex process record and replay
|
|
@cindex recording inferior's execution and replaying it
|
|
|
|
On some platforms, @value{GDBN} provides a special @dfn{process record
|
|
and replay} target that can record a log of the process execution, and
|
|
replay it later with both forward and reverse execution commands.
|
|
|
|
@cindex replay mode
|
|
When this target is in use, if the execution log includes the record
|
|
for the next instruction, @value{GDBN} will debug in @dfn{replay
|
|
mode}. In the replay mode, the inferior does not really execute code
|
|
instructions. Instead, all the events that normally happen during
|
|
code execution are taken from the execution log. While code is not
|
|
really executed in replay mode, the values of registers (including the
|
|
program counter register) and the memory of the inferior are still
|
|
changed as they normally would. Their contents are taken from the
|
|
execution log.
|
|
|
|
@cindex record mode
|
|
If the record for the next instruction is not in the execution log,
|
|
@value{GDBN} will debug in @dfn{record mode}. In this mode, the
|
|
inferior executes normally, and @value{GDBN} records the execution log
|
|
for future replay.
|
|
|
|
The process record and replay target supports reverse execution
|
|
(@pxref{Reverse Execution}), even if the platform on which the
|
|
inferior runs does not. However, the reverse execution is limited in
|
|
this case by the range of the instructions recorded in the execution
|
|
log. In other words, reverse execution on platforms that don't
|
|
support it directly can only be done in the replay mode.
|
|
|
|
When debugging in the reverse direction, @value{GDBN} will work in
|
|
replay mode as long as the execution log includes the record for the
|
|
previous instruction; otherwise, it will work in record mode, if the
|
|
platform supports reverse execution, or stop if not.
|
|
|
|
For architecture environments that support process record and replay,
|
|
@value{GDBN} provides the following commands:
|
|
|
|
@table @code
|
|
@kindex target record
|
|
@kindex record
|
|
@kindex rec
|
|
@item target record
|
|
This command starts the process record and replay target. The process
|
|
record and replay target can only debug a process that is already
|
|
running. Therefore, you need first to start the process with the
|
|
@kbd{run} or @kbd{start} commands, and then start the recording with
|
|
the @kbd{target record} command.
|
|
|
|
Both @code{record} and @code{rec} are aliases of @code{target record}.
|
|
|
|
@cindex displaced stepping, and process record and replay
|
|
Displaced stepping (@pxref{Maintenance Commands,, displaced stepping})
|
|
will be automatically disabled when process record and replay target
|
|
is started. That's because the process record and replay target
|
|
doesn't support displaced stepping.
|
|
|
|
@cindex non-stop mode, and process record and replay
|
|
@cindex asynchronous execution, and process record and replay
|
|
If the inferior is in the non-stop mode (@pxref{Non-Stop Mode}) or in
|
|
the asynchronous execution mode (@pxref{Background Execution}), the
|
|
process record and replay target cannot be started because it doesn't
|
|
support these two modes.
|
|
|
|
@kindex record stop
|
|
@kindex rec s
|
|
@item record stop
|
|
Stop the process record and replay target. When process record and
|
|
replay target stops, the entire execution log will be deleted and the
|
|
inferior will either be terminated, or will remain in its final state.
|
|
|
|
When you stop the process record and replay target in record mode (at
|
|
the end of the execution log), the inferior will be stopped at the
|
|
next instruction that would have been recorded. In other words, if
|
|
you record for a while and then stop recording, the inferior process
|
|
will be left in the same state as if the recording never happened.
|
|
|
|
On the other hand, if the process record and replay target is stopped
|
|
while in replay mode (that is, not at the end of the execution log,
|
|
but at some earlier point), the inferior process will become ``live''
|
|
at that earlier state, and it will then be possible to continue the
|
|
usual ``live'' debugging of the process from that state.
|
|
|
|
When the inferior process exits, or @value{GDBN} detaches from it,
|
|
process record and replay target will automatically stop itself.
|
|
|
|
@kindex record save
|
|
@item record save @var{filename}
|
|
Save the execution log to a file @file{@var{filename}}.
|
|
Default filename is @file{gdb_record.@var{process_id}}, where
|
|
@var{process_id} is the process ID of the inferior.
|
|
|
|
@kindex record restore
|
|
@item record restore @var{filename}
|
|
Restore the execution log from a file @file{@var{filename}}.
|
|
File must have been created with @code{record save}.
|
|
|
|
@kindex set record insn-number-max
|
|
@item set record insn-number-max @var{limit}
|
|
Set the limit of instructions to be recorded. Default value is 200000.
|
|
|
|
If @var{limit} is a positive number, then @value{GDBN} will start
|
|
deleting instructions from the log once the number of the record
|
|
instructions becomes greater than @var{limit}. For every new recorded
|
|
instruction, @value{GDBN} will delete the earliest recorded
|
|
instruction to keep the number of recorded instructions at the limit.
|
|
(Since deleting recorded instructions loses information, @value{GDBN}
|
|
lets you control what happens when the limit is reached, by means of
|
|
the @code{stop-at-limit} option, described below.)
|
|
|
|
If @var{limit} is zero, @value{GDBN} will never delete recorded
|
|
instructions from the execution log. The number of recorded
|
|
instructions is unlimited in this case.
|
|
|
|
@kindex show record insn-number-max
|
|
@item show record insn-number-max
|
|
Show the limit of instructions to be recorded.
|
|
|
|
@kindex set record stop-at-limit
|
|
@item set record stop-at-limit
|
|
Control the behavior when the number of recorded instructions reaches
|
|
the limit. If ON (the default), @value{GDBN} will stop when the limit
|
|
is reached for the first time and ask you whether you want to stop the
|
|
inferior or continue running it and recording the execution log. If
|
|
you decide to continue recording, each new recorded instruction will
|
|
cause the oldest one to be deleted.
|
|
|
|
If this option is OFF, @value{GDBN} will automatically delete the
|
|
oldest record to make room for each new one, without asking.
|
|
|
|
@kindex show record stop-at-limit
|
|
@item show record stop-at-limit
|
|
Show the current setting of @code{stop-at-limit}.
|
|
|
|
@kindex set record memory-query
|
|
@item set record memory-query
|
|
Control the behavior when @value{GDBN} is unable to record memory
|
|
changes caused by an instruction. If ON, @value{GDBN} will query
|
|
whether to stop the inferior in that case.
|
|
|
|
If this option is OFF (the default), @value{GDBN} will automatically
|
|
ignore the effect of such instructions on memory. Later, when
|
|
@value{GDBN} replays this execution log, it will mark the log of this
|
|
instruction as not accessible, and it will not affect the replay
|
|
results.
|
|
|
|
@kindex show record memory-query
|
|
@item show record memory-query
|
|
Show the current setting of @code{memory-query}.
|
|
|
|
@kindex info record
|
|
@item info record
|
|
Show various statistics about the state of process record and its
|
|
in-memory execution log buffer, including:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
Whether in record mode or replay mode.
|
|
@item
|
|
Lowest recorded instruction number (counting from when the current execution log started recording instructions).
|
|
@item
|
|
Highest recorded instruction number.
|
|
@item
|
|
Current instruction about to be replayed (if in replay mode).
|
|
@item
|
|
Number of instructions contained in the execution log.
|
|
@item
|
|
Maximum number of instructions that may be contained in the execution log.
|
|
@end itemize
|
|
|
|
@kindex record delete
|
|
@kindex rec del
|
|
@item record delete
|
|
When record target runs in replay mode (``in the past''), delete the
|
|
subsequent execution log and begin to record a new execution log starting
|
|
from the current address. This means you will abandon the previously
|
|
recorded ``future'' and begin recording a new ``future''.
|
|
@end table
|
|
|
|
|
|
@node Stack
|
|
@chapter Examining the Stack
|
|
|
|
When your program has stopped, the first thing you need to know is where it
|
|
stopped and how it got there.
|
|
|
|
@cindex call stack
|
|
Each time your program performs a function call, information about the call
|
|
is generated.
|
|
That information includes the location of the call in your program,
|
|
the arguments of the call,
|
|
and the local variables of the function being called.
|
|
The information is saved in a block of data called a @dfn{stack frame}.
|
|
The stack frames are allocated in a region of memory called the @dfn{call
|
|
stack}.
|
|
|
|
When your program stops, the @value{GDBN} commands for examining the
|
|
stack allow you to see all of this information.
|
|
|
|
@cindex selected frame
|
|
One of the stack frames is @dfn{selected} by @value{GDBN} and many
|
|
@value{GDBN} commands refer implicitly to the selected frame. In
|
|
particular, whenever you ask @value{GDBN} for the value of a variable in
|
|
your program, the value is found in the selected frame. There are
|
|
special @value{GDBN} commands to select whichever frame you are
|
|
interested in. @xref{Selection, ,Selecting a Frame}.
|
|
|
|
When your program stops, @value{GDBN} automatically selects the
|
|
currently executing frame and describes it briefly, similar to the
|
|
@code{frame} command (@pxref{Frame Info, ,Information about a Frame}).
|
|
|
|
@menu
|
|
* Frames:: Stack frames
|
|
* Backtrace:: Backtraces
|
|
* Selection:: Selecting a frame
|
|
* Frame Info:: Information on a frame
|
|
|
|
@end menu
|
|
|
|
@node Frames
|
|
@section Stack Frames
|
|
|
|
@cindex frame, definition
|
|
@cindex stack frame
|
|
The call stack is divided up into contiguous pieces called @dfn{stack
|
|
frames}, or @dfn{frames} for short; each frame is the data associated
|
|
with one call to one function. The frame contains the arguments given
|
|
to the function, the function's local variables, and the address at
|
|
which the function is executing.
|
|
|
|
@cindex initial frame
|
|
@cindex outermost frame
|
|
@cindex innermost frame
|
|
When your program is started, the stack has only one frame, that of the
|
|
function @code{main}. This is called the @dfn{initial} frame or the
|
|
@dfn{outermost} frame. Each time a function is called, a new frame is
|
|
made. Each time a function returns, the frame for that function invocation
|
|
is eliminated. If a function is recursive, there can be many frames for
|
|
the same function. The frame for the function in which execution is
|
|
actually occurring is called the @dfn{innermost} frame. This is the most
|
|
recently created of all the stack frames that still exist.
|
|
|
|
@cindex frame pointer
|
|
Inside your program, stack frames are identified by their addresses. A
|
|
stack frame consists of many bytes, each of which has its own address; each
|
|
kind of computer has a convention for choosing one byte whose
|
|
address serves as the address of the frame. Usually this address is kept
|
|
in a register called the @dfn{frame pointer register}
|
|
(@pxref{Registers, $fp}) while execution is going on in that frame.
|
|
|
|
@cindex frame number
|
|
@value{GDBN} assigns numbers to all existing stack frames, starting with
|
|
zero for the innermost frame, one for the frame that called it,
|
|
and so on upward. These numbers do not really exist in your program;
|
|
they are assigned by @value{GDBN} to give you a way of designating stack
|
|
frames in @value{GDBN} commands.
|
|
|
|
@c The -fomit-frame-pointer below perennially causes hbox overflow
|
|
@c underflow problems.
|
|
@cindex frameless execution
|
|
Some compilers provide a way to compile functions so that they operate
|
|
without stack frames. (For example, the @value{NGCC} option
|
|
@smallexample
|
|
@samp{-fomit-frame-pointer}
|
|
@end smallexample
|
|
generates functions without a frame.)
|
|
This is occasionally done with heavily used library functions to save
|
|
the frame setup time. @value{GDBN} has limited facilities for dealing
|
|
with these function invocations. If the innermost function invocation
|
|
has no stack frame, @value{GDBN} nevertheless regards it as though
|
|
it had a separate frame, which is numbered zero as usual, allowing
|
|
correct tracing of the function call chain. However, @value{GDBN} has
|
|
no provision for frameless functions elsewhere in the stack.
|
|
|
|
@table @code
|
|
@kindex frame@r{, command}
|
|
@cindex current stack frame
|
|
@item frame @var{args}
|
|
The @code{frame} command allows you to move from one stack frame to another,
|
|
and to print the stack frame you select. @var{args} may be either the
|
|
address of the frame or the stack frame number. Without an argument,
|
|
@code{frame} prints the current stack frame.
|
|
|
|
@kindex select-frame
|
|
@cindex selecting frame silently
|
|
@item select-frame
|
|
The @code{select-frame} command allows you to move from one stack frame
|
|
to another without printing the frame. This is the silent version of
|
|
@code{frame}.
|
|
@end table
|
|
|
|
@node Backtrace
|
|
@section Backtraces
|
|
|
|
@cindex traceback
|
|
@cindex call stack traces
|
|
A backtrace is a summary of how your program got where it is. It shows one
|
|
line per frame, for many frames, starting with the currently executing
|
|
frame (frame zero), followed by its caller (frame one), and on up the
|
|
stack.
|
|
|
|
@table @code
|
|
@kindex backtrace
|
|
@kindex bt @r{(@code{backtrace})}
|
|
@item backtrace
|
|
@itemx bt
|
|
Print a backtrace of the entire stack: one line per frame for all
|
|
frames in the stack.
|
|
|
|
You can stop the backtrace at any time by typing the system interrupt
|
|
character, normally @kbd{Ctrl-c}.
|
|
|
|
@item backtrace @var{n}
|
|
@itemx bt @var{n}
|
|
Similar, but print only the innermost @var{n} frames.
|
|
|
|
@item backtrace -@var{n}
|
|
@itemx bt -@var{n}
|
|
Similar, but print only the outermost @var{n} frames.
|
|
|
|
@item backtrace full
|
|
@itemx bt full
|
|
@itemx bt full @var{n}
|
|
@itemx bt full -@var{n}
|
|
Print the values of the local variables also. @var{n} specifies the
|
|
number of frames to print, as described above.
|
|
@end table
|
|
|
|
@kindex where
|
|
@kindex info stack
|
|
The names @code{where} and @code{info stack} (abbreviated @code{info s})
|
|
are additional aliases for @code{backtrace}.
|
|
|
|
@cindex multiple threads, backtrace
|
|
In a multi-threaded program, @value{GDBN} by default shows the
|
|
backtrace only for the current thread. To display the backtrace for
|
|
several or all of the threads, use the command @code{thread apply}
|
|
(@pxref{Threads, thread apply}). For example, if you type @kbd{thread
|
|
apply all backtrace}, @value{GDBN} will display the backtrace for all
|
|
the threads; this is handy when you debug a core dump of a
|
|
multi-threaded program.
|
|
|
|
Each line in the backtrace shows the frame number and the function name.
|
|
The program counter value is also shown---unless you use @code{set
|
|
print address off}. The backtrace also shows the source file name and
|
|
line number, as well as the arguments to the function. The program
|
|
counter value is omitted if it is at the beginning of the code for that
|
|
line number.
|
|
|
|
Here is an example of a backtrace. It was made with the command
|
|
@samp{bt 3}, so it shows the innermost three frames.
|
|
|
|
@smallexample
|
|
@group
|
|
#0 m4_traceon (obs=0x24eb0, argc=1, argv=0x2b8c8)
|
|
at builtin.c:993
|
|
#1 0x6e38 in expand_macro (sym=0x2b600, data=...) at macro.c:242
|
|
#2 0x6840 in expand_token (obs=0x0, t=177664, td=0xf7fffb08)
|
|
at macro.c:71
|
|
(More stack frames follow...)
|
|
@end group
|
|
@end smallexample
|
|
|
|
@noindent
|
|
The display for frame zero does not begin with a program counter
|
|
value, indicating that your program has stopped at the beginning of the
|
|
code for line @code{993} of @code{builtin.c}.
|
|
|
|
@noindent
|
|
The value of parameter @code{data} in frame 1 has been replaced by
|
|
@code{@dots{}}. By default, @value{GDBN} prints the value of a parameter
|
|
only if it is a scalar (integer, pointer, enumeration, etc). See command
|
|
@kbd{set print frame-arguments} in @ref{Print Settings} for more details
|
|
on how to configure the way function parameter values are printed.
|
|
|
|
@cindex optimized out, in backtrace
|
|
@cindex function call arguments, optimized out
|
|
If your program was compiled with optimizations, some compilers will
|
|
optimize away arguments passed to functions if those arguments are
|
|
never used after the call. Such optimizations generate code that
|
|
passes arguments through registers, but doesn't store those arguments
|
|
in the stack frame. @value{GDBN} has no way of displaying such
|
|
arguments in stack frames other than the innermost one. Here's what
|
|
such a backtrace might look like:
|
|
|
|
@smallexample
|
|
@group
|
|
#0 m4_traceon (obs=0x24eb0, argc=1, argv=0x2b8c8)
|
|
at builtin.c:993
|
|
#1 0x6e38 in expand_macro (sym=<optimized out>) at macro.c:242
|
|
#2 0x6840 in expand_token (obs=0x0, t=<optimized out>, td=0xf7fffb08)
|
|
at macro.c:71
|
|
(More stack frames follow...)
|
|
@end group
|
|
@end smallexample
|
|
|
|
@noindent
|
|
The values of arguments that were not saved in their stack frames are
|
|
shown as @samp{<optimized out>}.
|
|
|
|
If you need to display the values of such optimized-out arguments,
|
|
either deduce that from other variables whose values depend on the one
|
|
you are interested in, or recompile without optimizations.
|
|
|
|
@cindex backtrace beyond @code{main} function
|
|
@cindex program entry point
|
|
@cindex startup code, and backtrace
|
|
Most programs have a standard user entry point---a place where system
|
|
libraries and startup code transition into user code. For C this is
|
|
@code{main}@footnote{
|
|
Note that embedded programs (the so-called ``free-standing''
|
|
environment) are not required to have a @code{main} function as the
|
|
entry point. They could even have multiple entry points.}.
|
|
When @value{GDBN} finds the entry function in a backtrace
|
|
it will terminate the backtrace, to avoid tracing into highly
|
|
system-specific (and generally uninteresting) code.
|
|
|
|
If you need to examine the startup code, or limit the number of levels
|
|
in a backtrace, you can change this behavior:
|
|
|
|
@table @code
|
|
@item set backtrace past-main
|
|
@itemx set backtrace past-main on
|
|
@kindex set backtrace
|
|
Backtraces will continue past the user entry point.
|
|
|
|
@item set backtrace past-main off
|
|
Backtraces will stop when they encounter the user entry point. This is the
|
|
default.
|
|
|
|
@item show backtrace past-main
|
|
@kindex show backtrace
|
|
Display the current user entry point backtrace policy.
|
|
|
|
@item set backtrace past-entry
|
|
@itemx set backtrace past-entry on
|
|
Backtraces will continue past the internal entry point of an application.
|
|
This entry point is encoded by the linker when the application is built,
|
|
and is likely before the user entry point @code{main} (or equivalent) is called.
|
|
|
|
@item set backtrace past-entry off
|
|
Backtraces will stop when they encounter the internal entry point of an
|
|
application. This is the default.
|
|
|
|
@item show backtrace past-entry
|
|
Display the current internal entry point backtrace policy.
|
|
|
|
@item set backtrace limit @var{n}
|
|
@itemx set backtrace limit 0
|
|
@cindex backtrace limit
|
|
Limit the backtrace to @var{n} levels. A value of zero means
|
|
unlimited.
|
|
|
|
@item show backtrace limit
|
|
Display the current limit on backtrace levels.
|
|
@end table
|
|
|
|
@node Selection
|
|
@section Selecting a Frame
|
|
|
|
Most commands for examining the stack and other data in your program work on
|
|
whichever stack frame is selected at the moment. Here are the commands for
|
|
selecting a stack frame; all of them finish by printing a brief description
|
|
of the stack frame just selected.
|
|
|
|
@table @code
|
|
@kindex frame@r{, selecting}
|
|
@kindex f @r{(@code{frame})}
|
|
@item frame @var{n}
|
|
@itemx f @var{n}
|
|
Select frame number @var{n}. Recall that frame zero is the innermost
|
|
(currently executing) frame, frame one is the frame that called the
|
|
innermost one, and so on. The highest-numbered frame is the one for
|
|
@code{main}.
|
|
|
|
@item frame @var{addr}
|
|
@itemx f @var{addr}
|
|
Select the frame at address @var{addr}. This is useful mainly if the
|
|
chaining of stack frames has been damaged by a bug, making it
|
|
impossible for @value{GDBN} to assign numbers properly to all frames. In
|
|
addition, this can be useful when your program has multiple stacks and
|
|
switches between them.
|
|
|
|
On the SPARC architecture, @code{frame} needs two addresses to
|
|
select an arbitrary frame: a frame pointer and a stack pointer.
|
|
|
|
On the @acronym{MIPS} and Alpha architecture, it needs two addresses: a stack
|
|
pointer and a program counter.
|
|
|
|
On the 29k architecture, it needs three addresses: a register stack
|
|
pointer, a program counter, and a memory stack pointer.
|
|
|
|
@kindex up
|
|
@item up @var{n}
|
|
Move @var{n} frames up the stack. For positive numbers @var{n}, this
|
|
advances toward the outermost frame, to higher frame numbers, to frames
|
|
that have existed longer. @var{n} defaults to one.
|
|
|
|
@kindex down
|
|
@kindex do @r{(@code{down})}
|
|
@item down @var{n}
|
|
Move @var{n} frames down the stack. For positive numbers @var{n}, this
|
|
advances toward the innermost frame, to lower frame numbers, to frames
|
|
that were created more recently. @var{n} defaults to one. You may
|
|
abbreviate @code{down} as @code{do}.
|
|
@end table
|
|
|
|
All of these commands end by printing two lines of output describing the
|
|
frame. The first line shows the frame number, the function name, the
|
|
arguments, and the source file and line number of execution in that
|
|
frame. The second line shows the text of that source line.
|
|
|
|
@need 1000
|
|
For example:
|
|
|
|
@smallexample
|
|
@group
|
|
(@value{GDBP}) up
|
|
#1 0x22f0 in main (argc=1, argv=0xf7fffbf4, env=0xf7fffbfc)
|
|
at env.c:10
|
|
10 read_input_file (argv[i]);
|
|
@end group
|
|
@end smallexample
|
|
|
|
After such a printout, the @code{list} command with no arguments
|
|
prints ten lines centered on the point of execution in the frame.
|
|
You can also edit the program at the point of execution with your favorite
|
|
editing program by typing @code{edit}.
|
|
@xref{List, ,Printing Source Lines},
|
|
for details.
|
|
|
|
@table @code
|
|
@kindex down-silently
|
|
@kindex up-silently
|
|
@item up-silently @var{n}
|
|
@itemx down-silently @var{n}
|
|
These two commands are variants of @code{up} and @code{down},
|
|
respectively; they differ in that they do their work silently, without
|
|
causing display of the new frame. They are intended primarily for use
|
|
in @value{GDBN} command scripts, where the output might be unnecessary and
|
|
distracting.
|
|
@end table
|
|
|
|
@node Frame Info
|
|
@section Information About a Frame
|
|
|
|
There are several other commands to print information about the selected
|
|
stack frame.
|
|
|
|
@table @code
|
|
@item frame
|
|
@itemx f
|
|
When used without any argument, this command does not change which
|
|
frame is selected, but prints a brief description of the currently
|
|
selected stack frame. It can be abbreviated @code{f}. With an
|
|
argument, this command is used to select a stack frame.
|
|
@xref{Selection, ,Selecting a Frame}.
|
|
|
|
@kindex info frame
|
|
@kindex info f @r{(@code{info frame})}
|
|
@item info frame
|
|
@itemx info f
|
|
This command prints a verbose description of the selected stack frame,
|
|
including:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
the address of the frame
|
|
@item
|
|
the address of the next frame down (called by this frame)
|
|
@item
|
|
the address of the next frame up (caller of this frame)
|
|
@item
|
|
the language in which the source code corresponding to this frame is written
|
|
@item
|
|
the address of the frame's arguments
|
|
@item
|
|
the address of the frame's local variables
|
|
@item
|
|
the program counter saved in it (the address of execution in the caller frame)
|
|
@item
|
|
which registers were saved in the frame
|
|
@end itemize
|
|
|
|
@noindent The verbose description is useful when
|
|
something has gone wrong that has made the stack format fail to fit
|
|
the usual conventions.
|
|
|
|
@item info frame @var{addr}
|
|
@itemx info f @var{addr}
|
|
Print a verbose description of the frame at address @var{addr}, without
|
|
selecting that frame. The selected frame remains unchanged by this
|
|
command. This requires the same kind of address (more than one for some
|
|
architectures) that you specify in the @code{frame} command.
|
|
@xref{Selection, ,Selecting a Frame}.
|
|
|
|
@kindex info args
|
|
@item info args
|
|
Print the arguments of the selected frame, each on a separate line.
|
|
|
|
@item info locals
|
|
@kindex info locals
|
|
Print the local variables of the selected frame, each on a separate
|
|
line. These are all variables (declared either static or automatic)
|
|
accessible at the point of execution of the selected frame.
|
|
|
|
@end table
|
|
|
|
|
|
@node Source
|
|
@chapter Examining Source Files
|
|
|
|
@value{GDBN} can print parts of your program's source, since the debugging
|
|
information recorded in the program tells @value{GDBN} what source files were
|
|
used to build it. When your program stops, @value{GDBN} spontaneously prints
|
|
the line where it stopped. Likewise, when you select a stack frame
|
|
(@pxref{Selection, ,Selecting a Frame}), @value{GDBN} prints the line where
|
|
execution in that frame has stopped. You can print other portions of
|
|
source files by explicit command.
|
|
|
|
If you use @value{GDBN} through its @sc{gnu} Emacs interface, you may
|
|
prefer to use Emacs facilities to view source; see @ref{Emacs, ,Using
|
|
@value{GDBN} under @sc{gnu} Emacs}.
|
|
|
|
@menu
|
|
* List:: Printing source lines
|
|
* Specify Location:: How to specify code locations
|
|
* Edit:: Editing source files
|
|
* Search:: Searching source files
|
|
* Source Path:: Specifying source directories
|
|
* Machine Code:: Source and machine code
|
|
@end menu
|
|
|
|
@node List
|
|
@section Printing Source Lines
|
|
|
|
@kindex list
|
|
@kindex l @r{(@code{list})}
|
|
To print lines from a source file, use the @code{list} command
|
|
(abbreviated @code{l}). By default, ten lines are printed.
|
|
There are several ways to specify what part of the file you want to
|
|
print; see @ref{Specify Location}, for the full list.
|
|
|
|
Here are the forms of the @code{list} command most commonly used:
|
|
|
|
@table @code
|
|
@item list @var{linenum}
|
|
Print lines centered around line number @var{linenum} in the
|
|
current source file.
|
|
|
|
@item list @var{function}
|
|
Print lines centered around the beginning of function
|
|
@var{function}.
|
|
|
|
@item list
|
|
Print more lines. If the last lines printed were printed with a
|
|
@code{list} command, this prints lines following the last lines
|
|
printed; however, if the last line printed was a solitary line printed
|
|
as part of displaying a stack frame (@pxref{Stack, ,Examining the
|
|
Stack}), this prints lines centered around that line.
|
|
|
|
@item list -
|
|
Print lines just before the lines last printed.
|
|
@end table
|
|
|
|
@cindex @code{list}, how many lines to display
|
|
By default, @value{GDBN} prints ten source lines with any of these forms of
|
|
the @code{list} command. You can change this using @code{set listsize}:
|
|
|
|
@table @code
|
|
@kindex set listsize
|
|
@item set listsize @var{count}
|
|
Make the @code{list} command display @var{count} source lines (unless
|
|
the @code{list} argument explicitly specifies some other number).
|
|
|
|
@kindex show listsize
|
|
@item show listsize
|
|
Display the number of lines that @code{list} prints.
|
|
@end table
|
|
|
|
Repeating a @code{list} command with @key{RET} discards the argument,
|
|
so it is equivalent to typing just @code{list}. This is more useful
|
|
than listing the same lines again. An exception is made for an
|
|
argument of @samp{-}; that argument is preserved in repetition so that
|
|
each repetition moves up in the source file.
|
|
|
|
In general, the @code{list} command expects you to supply zero, one or two
|
|
@dfn{linespecs}. Linespecs specify source lines; there are several ways
|
|
of writing them (@pxref{Specify Location}), but the effect is always
|
|
to specify some source line.
|
|
|
|
Here is a complete description of the possible arguments for @code{list}:
|
|
|
|
@table @code
|
|
@item list @var{linespec}
|
|
Print lines centered around the line specified by @var{linespec}.
|
|
|
|
@item list @var{first},@var{last}
|
|
Print lines from @var{first} to @var{last}. Both arguments are
|
|
linespecs. When a @code{list} command has two linespecs, and the
|
|
source file of the second linespec is omitted, this refers to
|
|
the same source file as the first linespec.
|
|
|
|
@item list ,@var{last}
|
|
Print lines ending with @var{last}.
|
|
|
|
@item list @var{first},
|
|
Print lines starting with @var{first}.
|
|
|
|
@item list +
|
|
Print lines just after the lines last printed.
|
|
|
|
@item list -
|
|
Print lines just before the lines last printed.
|
|
|
|
@item list
|
|
As described in the preceding table.
|
|
@end table
|
|
|
|
@node Specify Location
|
|
@section Specifying a Location
|
|
@cindex specifying location
|
|
@cindex linespec
|
|
|
|
Several @value{GDBN} commands accept arguments that specify a location
|
|
of your program's code. Since @value{GDBN} is a source-level
|
|
debugger, a location usually specifies some line in the source code;
|
|
for that reason, locations are also known as @dfn{linespecs}.
|
|
|
|
Here are all the different ways of specifying a code location that
|
|
@value{GDBN} understands:
|
|
|
|
@table @code
|
|
@item @var{linenum}
|
|
Specifies the line number @var{linenum} of the current source file.
|
|
|
|
@item -@var{offset}
|
|
@itemx +@var{offset}
|
|
Specifies the line @var{offset} lines before or after the @dfn{current
|
|
line}. For the @code{list} command, the current line is the last one
|
|
printed; for the breakpoint commands, this is the line at which
|
|
execution stopped in the currently selected @dfn{stack frame}
|
|
(@pxref{Frames, ,Frames}, for a description of stack frames.) When
|
|
used as the second of the two linespecs in a @code{list} command,
|
|
this specifies the line @var{offset} lines up or down from the first
|
|
linespec.
|
|
|
|
@item @var{filename}:@var{linenum}
|
|
Specifies the line @var{linenum} in the source file @var{filename}.
|
|
If @var{filename} is a relative file name, then it will match any
|
|
source file name with the same trailing components. For example, if
|
|
@var{filename} is @samp{gcc/expr.c}, then it will match source file
|
|
name of @file{/build/trunk/gcc/expr.c}, but not
|
|
@file{/build/trunk/libcpp/expr.c} or @file{/build/trunk/gcc/x-expr.c}.
|
|
|
|
@item @var{function}
|
|
Specifies the line that begins the body of the function @var{function}.
|
|
For example, in C, this is the line with the open brace.
|
|
|
|
@item @var{function}:@var{label}
|
|
Specifies the line where @var{label} appears in @var{function}.
|
|
|
|
@item @var{filename}:@var{function}
|
|
Specifies the line that begins the body of the function @var{function}
|
|
in the file @var{filename}. You only need the file name with a
|
|
function name to avoid ambiguity when there are identically named
|
|
functions in different source files.
|
|
|
|
@item @var{label}
|
|
Specifies the line at which the label named @var{label} appears.
|
|
@value{GDBN} searches for the label in the function corresponding to
|
|
the currently selected stack frame. If there is no current selected
|
|
stack frame (for instance, if the inferior is not running), then
|
|
@value{GDBN} will not search for a label.
|
|
|
|
@item *@var{address}
|
|
Specifies the program address @var{address}. For line-oriented
|
|
commands, such as @code{list} and @code{edit}, this specifies a source
|
|
line that contains @var{address}. For @code{break} and other
|
|
breakpoint oriented commands, this can be used to set breakpoints in
|
|
parts of your program which do not have debugging information or
|
|
source files.
|
|
|
|
Here @var{address} may be any expression valid in the current working
|
|
language (@pxref{Languages, working language}) that specifies a code
|
|
address. In addition, as a convenience, @value{GDBN} extends the
|
|
semantics of expressions used in locations to cover the situations
|
|
that frequently happen during debugging. Here are the various forms
|
|
of @var{address}:
|
|
|
|
@table @code
|
|
@item @var{expression}
|
|
Any expression valid in the current working language.
|
|
|
|
@item @var{funcaddr}
|
|
An address of a function or procedure derived from its name. In C,
|
|
C@t{++}, Java, Objective-C, Fortran, minimal, and assembly, this is
|
|
simply the function's name @var{function} (and actually a special case
|
|
of a valid expression). In Pascal and Modula-2, this is
|
|
@code{&@var{function}}. In Ada, this is @code{@var{function}'Address}
|
|
(although the Pascal form also works).
|
|
|
|
This form specifies the address of the function's first instruction,
|
|
before the stack frame and arguments have been set up.
|
|
|
|
@item '@var{filename}'::@var{funcaddr}
|
|
Like @var{funcaddr} above, but also specifies the name of the source
|
|
file explicitly. This is useful if the name of the function does not
|
|
specify the function unambiguously, e.g., if there are several
|
|
functions with identical names in different source files.
|
|
@end table
|
|
|
|
@cindex breakpoint at static probe point
|
|
@item -pstap|-probe-stap @r{[}@var{objfile}:@r{[}@var{provider}:@r{]}@r{]}@var{name}
|
|
The @sc{gnu}/Linux tool @code{SystemTap} provides a way for
|
|
applications to embed static probes. @xref{Static Probe Points}, for more
|
|
information on finding and using static probes. This form of linespec
|
|
specifies the location of such a static probe.
|
|
|
|
If @var{objfile} is given, only probes coming from that shared library
|
|
or executable matching @var{objfile} as a regular expression are considered.
|
|
If @var{provider} is given, then only probes from that provider are considered.
|
|
If several probes match the spec, @value{GDBN} will insert a breakpoint at
|
|
each one of those probes.
|
|
|
|
@end table
|
|
|
|
|
|
@node Edit
|
|
@section Editing Source Files
|
|
@cindex editing source files
|
|
|
|
@kindex edit
|
|
@kindex e @r{(@code{edit})}
|
|
To edit the lines in a source file, use the @code{edit} command.
|
|
The editing program of your choice
|
|
is invoked with the current line set to
|
|
the active line in the program.
|
|
Alternatively, there are several ways to specify what part of the file you
|
|
want to print if you want to see other parts of the program:
|
|
|
|
@table @code
|
|
@item edit @var{location}
|
|
Edit the source file specified by @code{location}. Editing starts at
|
|
that @var{location}, e.g., at the specified source line of the
|
|
specified file. @xref{Specify Location}, for all the possible forms
|
|
of the @var{location} argument; here are the forms of the @code{edit}
|
|
command most commonly used:
|
|
|
|
@table @code
|
|
@item edit @var{number}
|
|
Edit the current source file with @var{number} as the active line number.
|
|
|
|
@item edit @var{function}
|
|
Edit the file containing @var{function} at the beginning of its definition.
|
|
@end table
|
|
|
|
@end table
|
|
|
|
@subsection Choosing your Editor
|
|
You can customize @value{GDBN} to use any editor you want
|
|
@footnote{
|
|
The only restriction is that your editor (say @code{ex}), recognizes the
|
|
following command-line syntax:
|
|
@smallexample
|
|
ex +@var{number} file
|
|
@end smallexample
|
|
The optional numeric value +@var{number} specifies the number of the line in
|
|
the file where to start editing.}.
|
|
By default, it is @file{@value{EDITOR}}, but you can change this
|
|
by setting the environment variable @code{EDITOR} before using
|
|
@value{GDBN}. For example, to configure @value{GDBN} to use the
|
|
@code{vi} editor, you could use these commands with the @code{sh} shell:
|
|
@smallexample
|
|
EDITOR=/usr/bin/vi
|
|
export EDITOR
|
|
gdb @dots{}
|
|
@end smallexample
|
|
or in the @code{csh} shell,
|
|
@smallexample
|
|
setenv EDITOR /usr/bin/vi
|
|
gdb @dots{}
|
|
@end smallexample
|
|
|
|
@node Search
|
|
@section Searching Source Files
|
|
@cindex searching source files
|
|
|
|
There are two commands for searching through the current source file for a
|
|
regular expression.
|
|
|
|
@table @code
|
|
@kindex search
|
|
@kindex forward-search
|
|
@item forward-search @var{regexp}
|
|
@itemx search @var{regexp}
|
|
The command @samp{forward-search @var{regexp}} checks each line,
|
|
starting with the one following the last line listed, for a match for
|
|
@var{regexp}. It lists the line that is found. You can use the
|
|
synonym @samp{search @var{regexp}} or abbreviate the command name as
|
|
@code{fo}.
|
|
|
|
@kindex reverse-search
|
|
@item reverse-search @var{regexp}
|
|
The command @samp{reverse-search @var{regexp}} checks each line, starting
|
|
with the one before the last line listed and going backward, for a match
|
|
for @var{regexp}. It lists the line that is found. You can abbreviate
|
|
this command as @code{rev}.
|
|
@end table
|
|
|
|
@node Source Path
|
|
@section Specifying Source Directories
|
|
|
|
@cindex source path
|
|
@cindex directories for source files
|
|
Executable programs sometimes do not record the directories of the source
|
|
files from which they were compiled, just the names. Even when they do,
|
|
the directories could be moved between the compilation and your debugging
|
|
session. @value{GDBN} has a list of directories to search for source files;
|
|
this is called the @dfn{source path}. Each time @value{GDBN} wants a source file,
|
|
it tries all the directories in the list, in the order they are present
|
|
in the list, until it finds a file with the desired name.
|
|
|
|
For example, suppose an executable references the file
|
|
@file{/usr/src/foo-1.0/lib/foo.c}, and our source path is
|
|
@file{/mnt/cross}. The file is first looked up literally; if this
|
|
fails, @file{/mnt/cross/usr/src/foo-1.0/lib/foo.c} is tried; if this
|
|
fails, @file{/mnt/cross/foo.c} is opened; if this fails, an error
|
|
message is printed. @value{GDBN} does not look up the parts of the
|
|
source file name, such as @file{/mnt/cross/src/foo-1.0/lib/foo.c}.
|
|
Likewise, the subdirectories of the source path are not searched: if
|
|
the source path is @file{/mnt/cross}, and the binary refers to
|
|
@file{foo.c}, @value{GDBN} would not find it under
|
|
@file{/mnt/cross/usr/src/foo-1.0/lib}.
|
|
|
|
Plain file names, relative file names with leading directories, file
|
|
names containing dots, etc.@: are all treated as described above; for
|
|
instance, if the source path is @file{/mnt/cross}, and the source file
|
|
is recorded as @file{../lib/foo.c}, @value{GDBN} would first try
|
|
@file{../lib/foo.c}, then @file{/mnt/cross/../lib/foo.c}, and after
|
|
that---@file{/mnt/cross/foo.c}.
|
|
|
|
Note that the executable search path is @emph{not} used to locate the
|
|
source files.
|
|
|
|
Whenever you reset or rearrange the source path, @value{GDBN} clears out
|
|
any information it has cached about where source files are found and where
|
|
each line is in the file.
|
|
|
|
@kindex directory
|
|
@kindex dir
|
|
When you start @value{GDBN}, its source path includes only @samp{cdir}
|
|
and @samp{cwd}, in that order.
|
|
To add other directories, use the @code{directory} command.
|
|
|
|
The search path is used to find both program source files and @value{GDBN}
|
|
script files (read using the @samp{-command} option and @samp{source} command).
|
|
|
|
In addition to the source path, @value{GDBN} provides a set of commands
|
|
that manage a list of source path substitution rules. A @dfn{substitution
|
|
rule} specifies how to rewrite source directories stored in the program's
|
|
debug information in case the sources were moved to a different
|
|
directory between compilation and debugging. A rule is made of
|
|
two strings, the first specifying what needs to be rewritten in
|
|
the path, and the second specifying how it should be rewritten.
|
|
In @ref{set substitute-path}, we name these two parts @var{from} and
|
|
@var{to} respectively. @value{GDBN} does a simple string replacement
|
|
of @var{from} with @var{to} at the start of the directory part of the
|
|
source file name, and uses that result instead of the original file
|
|
name to look up the sources.
|
|
|
|
Using the previous example, suppose the @file{foo-1.0} tree has been
|
|
moved from @file{/usr/src} to @file{/mnt/cross}, then you can tell
|
|
@value{GDBN} to replace @file{/usr/src} in all source path names with
|
|
@file{/mnt/cross}. The first lookup will then be
|
|
@file{/mnt/cross/foo-1.0/lib/foo.c} in place of the original location
|
|
of @file{/usr/src/foo-1.0/lib/foo.c}. To define a source path
|
|
substitution rule, use the @code{set substitute-path} command
|
|
(@pxref{set substitute-path}).
|
|
|
|
To avoid unexpected substitution results, a rule is applied only if the
|
|
@var{from} part of the directory name ends at a directory separator.
|
|
For instance, a rule substituting @file{/usr/source} into
|
|
@file{/mnt/cross} will be applied to @file{/usr/source/foo-1.0} but
|
|
not to @file{/usr/sourceware/foo-2.0}. And because the substitution
|
|
is applied only at the beginning of the directory name, this rule will
|
|
not be applied to @file{/root/usr/source/baz.c} either.
|
|
|
|
In many cases, you can achieve the same result using the @code{directory}
|
|
command. However, @code{set substitute-path} can be more efficient in
|
|
the case where the sources are organized in a complex tree with multiple
|
|
subdirectories. With the @code{directory} command, you need to add each
|
|
subdirectory of your project. If you moved the entire tree while
|
|
preserving its internal organization, then @code{set substitute-path}
|
|
allows you to direct the debugger to all the sources with one single
|
|
command.
|
|
|
|
@code{set substitute-path} is also more than just a shortcut command.
|
|
The source path is only used if the file at the original location no
|
|
longer exists. On the other hand, @code{set substitute-path} modifies
|
|
the debugger behavior to look at the rewritten location instead. So, if
|
|
for any reason a source file that is not relevant to your executable is
|
|
located at the original location, a substitution rule is the only
|
|
method available to point @value{GDBN} at the new location.
|
|
|
|
@cindex @samp{--with-relocated-sources}
|
|
@cindex default source path substitution
|
|
You can configure a default source path substitution rule by
|
|
configuring @value{GDBN} with the
|
|
@samp{--with-relocated-sources=@var{dir}} option. The @var{dir}
|
|
should be the name of a directory under @value{GDBN}'s configured
|
|
prefix (set with @samp{--prefix} or @samp{--exec-prefix}), and
|
|
directory names in debug information under @var{dir} will be adjusted
|
|
automatically if the installed @value{GDBN} is moved to a new
|
|
location. This is useful if @value{GDBN}, libraries or executables
|
|
with debug information and corresponding source code are being moved
|
|
together.
|
|
|
|
@table @code
|
|
@item directory @var{dirname} @dots{}
|
|
@item dir @var{dirname} @dots{}
|
|
Add directory @var{dirname} to the front of the source path. Several
|
|
directory names may be given to this command, separated by @samp{:}
|
|
(@samp{;} on MS-DOS and MS-Windows, where @samp{:} usually appears as
|
|
part of absolute file names) or
|
|
whitespace. You may specify a directory that is already in the source
|
|
path; this moves it forward, so @value{GDBN} searches it sooner.
|
|
|
|
@kindex cdir
|
|
@kindex cwd
|
|
@vindex $cdir@r{, convenience variable}
|
|
@vindex $cwd@r{, convenience variable}
|
|
@cindex compilation directory
|
|
@cindex current directory
|
|
@cindex working directory
|
|
@cindex directory, current
|
|
@cindex directory, compilation
|
|
You can use the string @samp{$cdir} to refer to the compilation
|
|
directory (if one is recorded), and @samp{$cwd} to refer to the current
|
|
working directory. @samp{$cwd} is not the same as @samp{.}---the former
|
|
tracks the current working directory as it changes during your @value{GDBN}
|
|
session, while the latter is immediately expanded to the current
|
|
directory at the time you add an entry to the source path.
|
|
|
|
@item directory
|
|
Reset the source path to its default value (@samp{$cdir:$cwd} on Unix systems). This requires confirmation.
|
|
|
|
@c RET-repeat for @code{directory} is explicitly disabled, but since
|
|
@c repeating it would be a no-op we do not say that. (thanks to RMS)
|
|
|
|
@item set directories @var{path-list}
|
|
@kindex set directories
|
|
Set the source path to @var{path-list}.
|
|
@samp{$cdir:$cwd} are added if missing.
|
|
|
|
@item show directories
|
|
@kindex show directories
|
|
Print the source path: show which directories it contains.
|
|
|
|
@anchor{set substitute-path}
|
|
@item set substitute-path @var{from} @var{to}
|
|
@kindex set substitute-path
|
|
Define a source path substitution rule, and add it at the end of the
|
|
current list of existing substitution rules. If a rule with the same
|
|
@var{from} was already defined, then the old rule is also deleted.
|
|
|
|
For example, if the file @file{/foo/bar/baz.c} was moved to
|
|
@file{/mnt/cross/baz.c}, then the command
|
|
|
|
@smallexample
|
|
(@value{GDBP}) set substitute-path /usr/src /mnt/cross
|
|
@end smallexample
|
|
|
|
@noindent
|
|
will tell @value{GDBN} to replace @samp{/usr/src} with
|
|
@samp{/mnt/cross}, which will allow @value{GDBN} to find the file
|
|
@file{baz.c} even though it was moved.
|
|
|
|
In the case when more than one substitution rule have been defined,
|
|
the rules are evaluated one by one in the order where they have been
|
|
defined. The first one matching, if any, is selected to perform
|
|
the substitution.
|
|
|
|
For instance, if we had entered the following commands:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) set substitute-path /usr/src/include /mnt/include
|
|
(@value{GDBP}) set substitute-path /usr/src /mnt/src
|
|
@end smallexample
|
|
|
|
@noindent
|
|
@value{GDBN} would then rewrite @file{/usr/src/include/defs.h} into
|
|
@file{/mnt/include/defs.h} by using the first rule. However, it would
|
|
use the second rule to rewrite @file{/usr/src/lib/foo.c} into
|
|
@file{/mnt/src/lib/foo.c}.
|
|
|
|
|
|
@item unset substitute-path [path]
|
|
@kindex unset substitute-path
|
|
If a path is specified, search the current list of substitution rules
|
|
for a rule that would rewrite that path. Delete that rule if found.
|
|
A warning is emitted by the debugger if no rule could be found.
|
|
|
|
If no path is specified, then all substitution rules are deleted.
|
|
|
|
@item show substitute-path [path]
|
|
@kindex show substitute-path
|
|
If a path is specified, then print the source path substitution rule
|
|
which would rewrite that path, if any.
|
|
|
|
If no path is specified, then print all existing source path substitution
|
|
rules.
|
|
|
|
@end table
|
|
|
|
If your source path is cluttered with directories that are no longer of
|
|
interest, @value{GDBN} may sometimes cause confusion by finding the wrong
|
|
versions of source. You can correct the situation as follows:
|
|
|
|
@enumerate
|
|
@item
|
|
Use @code{directory} with no argument to reset the source path to its default value.
|
|
|
|
@item
|
|
Use @code{directory} with suitable arguments to reinstall the
|
|
directories you want in the source path. You can add all the
|
|
directories in one command.
|
|
@end enumerate
|
|
|
|
@node Machine Code
|
|
@section Source and Machine Code
|
|
@cindex source line and its code address
|
|
|
|
You can use the command @code{info line} to map source lines to program
|
|
addresses (and vice versa), and the command @code{disassemble} to display
|
|
a range of addresses as machine instructions. You can use the command
|
|
@code{set disassemble-next-line} to set whether to disassemble next
|
|
source line when execution stops. When run under @sc{gnu} Emacs
|
|
mode, the @code{info line} command causes the arrow to point to the
|
|
line specified. Also, @code{info line} prints addresses in symbolic form as
|
|
well as hex.
|
|
|
|
@table @code
|
|
@kindex info line
|
|
@item info line @var{linespec}
|
|
Print the starting and ending addresses of the compiled code for
|
|
source line @var{linespec}. You can specify source lines in any of
|
|
the ways documented in @ref{Specify Location}.
|
|
@end table
|
|
|
|
For example, we can use @code{info line} to discover the location of
|
|
the object code for the first line of function
|
|
@code{m4_changequote}:
|
|
|
|
@c FIXME: I think this example should also show the addresses in
|
|
@c symbolic form, as they usually would be displayed.
|
|
@smallexample
|
|
(@value{GDBP}) info line m4_changequote
|
|
Line 895 of "builtin.c" starts at pc 0x634c and ends at 0x6350.
|
|
@end smallexample
|
|
|
|
@noindent
|
|
@cindex code address and its source line
|
|
We can also inquire (using @code{*@var{addr}} as the form for
|
|
@var{linespec}) what source line covers a particular address:
|
|
@smallexample
|
|
(@value{GDBP}) info line *0x63ff
|
|
Line 926 of "builtin.c" starts at pc 0x63e4 and ends at 0x6404.
|
|
@end smallexample
|
|
|
|
@cindex @code{$_} and @code{info line}
|
|
@cindex @code{x} command, default address
|
|
@kindex x@r{(examine), and} info line
|
|
After @code{info line}, the default address for the @code{x} command
|
|
is changed to the starting address of the line, so that @samp{x/i} is
|
|
sufficient to begin examining the machine code (@pxref{Memory,
|
|
,Examining Memory}). Also, this address is saved as the value of the
|
|
convenience variable @code{$_} (@pxref{Convenience Vars, ,Convenience
|
|
Variables}).
|
|
|
|
@table @code
|
|
@kindex disassemble
|
|
@cindex assembly instructions
|
|
@cindex instructions, assembly
|
|
@cindex machine instructions
|
|
@cindex listing machine instructions
|
|
@item disassemble
|
|
@itemx disassemble /m
|
|
@itemx disassemble /r
|
|
This specialized command dumps a range of memory as machine
|
|
instructions. It can also print mixed source+disassembly by specifying
|
|
the @code{/m} modifier and print the raw instructions in hex as well as
|
|
in symbolic form by specifying the @code{/r}.
|
|
The default memory range is the function surrounding the
|
|
program counter of the selected frame. A single argument to this
|
|
command is a program counter value; @value{GDBN} dumps the function
|
|
surrounding this value. When two arguments are given, they should
|
|
be separated by a comma, possibly surrounded by whitespace. The
|
|
arguments specify a range of addresses to dump, in one of two forms:
|
|
|
|
@table @code
|
|
@item @var{start},@var{end}
|
|
the addresses from @var{start} (inclusive) to @var{end} (exclusive)
|
|
@item @var{start},+@var{length}
|
|
the addresses from @var{start} (inclusive) to
|
|
@code{@var{start}+@var{length}} (exclusive).
|
|
@end table
|
|
|
|
@noindent
|
|
When 2 arguments are specified, the name of the function is also
|
|
printed (since there could be several functions in the given range).
|
|
|
|
The argument(s) can be any expression yielding a numeric value, such as
|
|
@samp{0x32c4}, @samp{&main+10} or @samp{$pc - 8}.
|
|
|
|
If the range of memory being disassembled contains current program counter,
|
|
the instruction at that location is shown with a @code{=>} marker.
|
|
@end table
|
|
|
|
The following example shows the disassembly of a range of addresses of
|
|
HP PA-RISC 2.0 code:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) disas 0x32c4, 0x32e4
|
|
Dump of assembler code from 0x32c4 to 0x32e4:
|
|
0x32c4 <main+204>: addil 0,dp
|
|
0x32c8 <main+208>: ldw 0x22c(sr0,r1),r26
|
|
0x32cc <main+212>: ldil 0x3000,r31
|
|
0x32d0 <main+216>: ble 0x3f8(sr4,r31)
|
|
0x32d4 <main+220>: ldo 0(r31),rp
|
|
0x32d8 <main+224>: addil -0x800,dp
|
|
0x32dc <main+228>: ldo 0x588(r1),r26
|
|
0x32e0 <main+232>: ldil 0x3000,r31
|
|
End of assembler dump.
|
|
@end smallexample
|
|
|
|
Here is an example showing mixed source+assembly for Intel x86, when the
|
|
program is stopped just after function prologue:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) disas /m main
|
|
Dump of assembler code for function main:
|
|
5 @{
|
|
0x08048330 <+0>: push %ebp
|
|
0x08048331 <+1>: mov %esp,%ebp
|
|
0x08048333 <+3>: sub $0x8,%esp
|
|
0x08048336 <+6>: and $0xfffffff0,%esp
|
|
0x08048339 <+9>: sub $0x10,%esp
|
|
|
|
6 printf ("Hello.\n");
|
|
=> 0x0804833c <+12>: movl $0x8048440,(%esp)
|
|
0x08048343 <+19>: call 0x8048284 <puts@@plt>
|
|
|
|
7 return 0;
|
|
8 @}
|
|
0x08048348 <+24>: mov $0x0,%eax
|
|
0x0804834d <+29>: leave
|
|
0x0804834e <+30>: ret
|
|
|
|
End of assembler dump.
|
|
@end smallexample
|
|
|
|
Here is another example showing raw instructions in hex for AMD x86-64,
|
|
|
|
@smallexample
|
|
(gdb) disas /r 0x400281,+10
|
|
Dump of assembler code from 0x400281 to 0x40028b:
|
|
0x0000000000400281: 38 36 cmp %dh,(%rsi)
|
|
0x0000000000400283: 2d 36 34 2e 73 sub $0x732e3436,%eax
|
|
0x0000000000400288: 6f outsl %ds:(%rsi),(%dx)
|
|
0x0000000000400289: 2e 32 00 xor %cs:(%rax),%al
|
|
End of assembler dump.
|
|
@end smallexample
|
|
|
|
Some architectures have more than one commonly-used set of instruction
|
|
mnemonics or other syntax.
|
|
|
|
For programs that were dynamically linked and use shared libraries,
|
|
instructions that call functions or branch to locations in the shared
|
|
libraries might show a seemingly bogus location---it's actually a
|
|
location of the relocation table. On some architectures, @value{GDBN}
|
|
might be able to resolve these to actual function names.
|
|
|
|
@table @code
|
|
@kindex set disassembly-flavor
|
|
@cindex Intel disassembly flavor
|
|
@cindex AT&T disassembly flavor
|
|
@item set disassembly-flavor @var{instruction-set}
|
|
Select the instruction set to use when disassembling the
|
|
program via the @code{disassemble} or @code{x/i} commands.
|
|
|
|
Currently this command is only defined for the Intel x86 family. You
|
|
can set @var{instruction-set} to either @code{intel} or @code{att}.
|
|
The default is @code{att}, the AT&T flavor used by default by Unix
|
|
assemblers for x86-based targets.
|
|
|
|
@kindex show disassembly-flavor
|
|
@item show disassembly-flavor
|
|
Show the current setting of the disassembly flavor.
|
|
@end table
|
|
|
|
@table @code
|
|
@kindex set disassemble-next-line
|
|
@kindex show disassemble-next-line
|
|
@item set disassemble-next-line
|
|
@itemx show disassemble-next-line
|
|
Control whether or not @value{GDBN} will disassemble the next source
|
|
line or instruction when execution stops. If ON, @value{GDBN} will
|
|
display disassembly of the next source line when execution of the
|
|
program being debugged stops. This is @emph{in addition} to
|
|
displaying the source line itself, which @value{GDBN} always does if
|
|
possible. If the next source line cannot be displayed for some reason
|
|
(e.g., if @value{GDBN} cannot find the source file, or there's no line
|
|
info in the debug info), @value{GDBN} will display disassembly of the
|
|
next @emph{instruction} instead of showing the next source line. If
|
|
AUTO, @value{GDBN} will display disassembly of next instruction only
|
|
if the source line cannot be displayed. This setting causes
|
|
@value{GDBN} to display some feedback when you step through a function
|
|
with no line info or whose source file is unavailable. The default is
|
|
OFF, which means never display the disassembly of the next line or
|
|
instruction.
|
|
@end table
|
|
|
|
|
|
@node Data
|
|
@chapter Examining Data
|
|
|
|
@cindex printing data
|
|
@cindex examining data
|
|
@kindex print
|
|
@kindex inspect
|
|
@c "inspect" is not quite a synonym if you are using Epoch, which we do not
|
|
@c document because it is nonstandard... Under Epoch it displays in a
|
|
@c different window or something like that.
|
|
The usual way to examine data in your program is with the @code{print}
|
|
command (abbreviated @code{p}), or its synonym @code{inspect}. It
|
|
evaluates and prints the value of an expression of the language your
|
|
program is written in (@pxref{Languages, ,Using @value{GDBN} with
|
|
Different Languages}). It may also print the expression using a
|
|
Python-based pretty-printer (@pxref{Pretty Printing}).
|
|
|
|
@table @code
|
|
@item print @var{expr}
|
|
@itemx print /@var{f} @var{expr}
|
|
@var{expr} is an expression (in the source language). By default the
|
|
value of @var{expr} is printed in a format appropriate to its data type;
|
|
you can choose a different format by specifying @samp{/@var{f}}, where
|
|
@var{f} is a letter specifying the format; see @ref{Output Formats,,Output
|
|
Formats}.
|
|
|
|
@item print
|
|
@itemx print /@var{f}
|
|
@cindex reprint the last value
|
|
If you omit @var{expr}, @value{GDBN} displays the last value again (from the
|
|
@dfn{value history}; @pxref{Value History, ,Value History}). This allows you to
|
|
conveniently inspect the same value in an alternative format.
|
|
@end table
|
|
|
|
A more low-level way of examining data is with the @code{x} command.
|
|
It examines data in memory at a specified address and prints it in a
|
|
specified format. @xref{Memory, ,Examining Memory}.
|
|
|
|
If you are interested in information about types, or about how the
|
|
fields of a struct or a class are declared, use the @code{ptype @var{exp}}
|
|
command rather than @code{print}. @xref{Symbols, ,Examining the Symbol
|
|
Table}.
|
|
|
|
@cindex exploring hierarchical data structures
|
|
@kindex explore
|
|
Another way of examining values of expressions and type information is
|
|
through the Python extension command @code{explore} (available only if
|
|
the @value{GDBN} build is configured with @code{--with-python}). It
|
|
offers an interactive way to start at the highest level (or, the most
|
|
abstract level) of the data type of an expression (or, the data type
|
|
itself) and explore all the way down to leaf scalar values/fields
|
|
embedded in the higher level data types.
|
|
|
|
@table @code
|
|
@item explore @var{arg}
|
|
@var{arg} is either an expression (in the source language), or a type
|
|
visible in the current context of the program being debugged.
|
|
@end table
|
|
|
|
The working of the @code{explore} command can be illustrated with an
|
|
example. If a data type @code{struct ComplexStruct} is defined in your
|
|
C program as
|
|
|
|
@smallexample
|
|
struct SimpleStruct
|
|
@{
|
|
int i;
|
|
double d;
|
|
@};
|
|
|
|
struct ComplexStruct
|
|
@{
|
|
struct SimpleStruct *ss_p;
|
|
int arr[10];
|
|
@};
|
|
@end smallexample
|
|
|
|
@noindent
|
|
followed by variable declarations as
|
|
|
|
@smallexample
|
|
struct SimpleStruct ss = @{ 10, 1.11 @};
|
|
struct ComplexStruct cs = @{ &ss, @{ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 @} @};
|
|
@end smallexample
|
|
|
|
@noindent
|
|
then, the value of the variable @code{cs} can be explored using the
|
|
@code{explore} command as follows.
|
|
|
|
@smallexample
|
|
(gdb) explore cs
|
|
The value of `cs' is a struct/class of type `struct ComplexStruct' with
|
|
the following fields:
|
|
|
|
ss_p = <Enter 0 to explore this field of type `struct SimpleStruct *'>
|
|
arr = <Enter 1 to explore this field of type `int [10]'>
|
|
|
|
Enter the field number of choice:
|
|
@end smallexample
|
|
|
|
@noindent
|
|
Since the fields of @code{cs} are not scalar values, you are being
|
|
prompted to chose the field you want to explore. Let's say you choose
|
|
the field @code{ss_p} by entering @code{0}. Then, since this field is a
|
|
pointer, you will be asked if it is pointing to a single value. From
|
|
the declaration of @code{cs} above, it is indeed pointing to a single
|
|
value, hence you enter @code{y}. If you enter @code{n}, then you will
|
|
be asked if it were pointing to an array of values, in which case this
|
|
field will be explored as if it were an array.
|
|
|
|
@smallexample
|
|
`cs.ss_p' is a pointer to a value of type `struct SimpleStruct'
|
|
Continue exploring it as a pointer to a single value [y/n]: y
|
|
The value of `*(cs.ss_p)' is a struct/class of type `struct
|
|
SimpleStruct' with the following fields:
|
|
|
|
i = 10 .. (Value of type `int')
|
|
d = 1.1100000000000001 .. (Value of type `double')
|
|
|
|
Press enter to return to parent value:
|
|
@end smallexample
|
|
|
|
@noindent
|
|
If the field @code{arr} of @code{cs} was chosen for exploration by
|
|
entering @code{1} earlier, then since it is as array, you will be
|
|
prompted to enter the index of the element in the array that you want
|
|
to explore.
|
|
|
|
@smallexample
|
|
`cs.arr' is an array of `int'.
|
|
Enter the index of the element you want to explore in `cs.arr': 5
|
|
|
|
`(cs.arr)[5]' is a scalar value of type `int'.
|
|
|
|
(cs.arr)[5] = 4
|
|
|
|
Press enter to return to parent value:
|
|
@end smallexample
|
|
|
|
In general, at any stage of exploration, you can go deeper towards the
|
|
leaf values by responding to the prompts appropriately, or hit the
|
|
return key to return to the enclosing data structure (the @i{higher}
|
|
level data structure).
|
|
|
|
Similar to exploring values, you can use the @code{explore} command to
|
|
explore types. Instead of specifying a value (which is typically a
|
|
variable name or an expression valid in the current context of the
|
|
program being debugged), you specify a type name. If you consider the
|
|
same example as above, your can explore the type
|
|
@code{struct ComplexStruct} by passing the argument
|
|
@code{struct ComplexStruct} to the @code{explore} command.
|
|
|
|
@smallexample
|
|
(gdb) explore struct ComplexStruct
|
|
@end smallexample
|
|
|
|
@noindent
|
|
By responding to the prompts appropriately in the subsequent interactive
|
|
session, you can explore the type @code{struct ComplexStruct} in a
|
|
manner similar to how the value @code{cs} was explored in the above
|
|
example.
|
|
|
|
The @code{explore} command also has two sub-commands,
|
|
@code{explore value} and @code{explore type}. The former sub-command is
|
|
a way to explicitly specify that value exploration of the argument is
|
|
being invoked, while the latter is a way to explicitly specify that type
|
|
exploration of the argument is being invoked.
|
|
|
|
@table @code
|
|
@item explore value @var{expr}
|
|
@cindex explore value
|
|
This sub-command of @code{explore} explores the value of the
|
|
expression @var{expr} (if @var{expr} is an expression valid in the
|
|
current context of the program being debugged). The behavior of this
|
|
command is identical to that of the behavior of the @code{explore}
|
|
command being passed the argument @var{expr}.
|
|
|
|
@item explore type @var{arg}
|
|
@cindex explore type
|
|
This sub-command of @code{explore} explores the type of @var{arg} (if
|
|
@var{arg} is a type visible in the current context of program being
|
|
debugged), or the type of the value/expression @var{arg} (if @var{arg}
|
|
is an expression valid in the current context of the program being
|
|
debugged). If @var{arg} is a type, then the behavior of this command is
|
|
identical to that of the @code{explore} command being passed the
|
|
argument @var{arg}. If @var{arg} is an expression, then the behavior of
|
|
this command will be identical to that of the @code{explore} command
|
|
being passed the type of @var{arg} as the argument.
|
|
@end table
|
|
|
|
@menu
|
|
* Expressions:: Expressions
|
|
* Ambiguous Expressions:: Ambiguous Expressions
|
|
* Variables:: Program variables
|
|
* Arrays:: Artificial arrays
|
|
* Output Formats:: Output formats
|
|
* Memory:: Examining memory
|
|
* Auto Display:: Automatic display
|
|
* Print Settings:: Print settings
|
|
* Pretty Printing:: Python pretty printing
|
|
* Value History:: Value history
|
|
* Convenience Vars:: Convenience variables
|
|
* Registers:: Registers
|
|
* Floating Point Hardware:: Floating point hardware
|
|
* Vector Unit:: Vector Unit
|
|
* OS Information:: Auxiliary data provided by operating system
|
|
* Memory Region Attributes:: Memory region attributes
|
|
* Dump/Restore Files:: Copy between memory and a file
|
|
* Core File Generation:: Cause a program dump its core
|
|
* Character Sets:: Debugging programs that use a different
|
|
character set than GDB does
|
|
* Caching Remote Data:: Data caching for remote targets
|
|
* Searching Memory:: Searching memory for a sequence of bytes
|
|
@end menu
|
|
|
|
@node Expressions
|
|
@section Expressions
|
|
|
|
@cindex expressions
|
|
@code{print} and many other @value{GDBN} commands accept an expression and
|
|
compute its value. Any kind of constant, variable or operator defined
|
|
by the programming language you are using is valid in an expression in
|
|
@value{GDBN}. This includes conditional expressions, function calls,
|
|
casts, and string constants. It also includes preprocessor macros, if
|
|
you compiled your program to include this information; see
|
|
@ref{Compilation}.
|
|
|
|
@cindex arrays in expressions
|
|
@value{GDBN} supports array constants in expressions input by
|
|
the user. The syntax is @{@var{element}, @var{element}@dots{}@}. For example,
|
|
you can use the command @code{print @{1, 2, 3@}} to create an array
|
|
of three integers. If you pass an array to a function or assign it
|
|
to a program variable, @value{GDBN} copies the array to memory that
|
|
is @code{malloc}ed in the target program.
|
|
|
|
Because C is so widespread, most of the expressions shown in examples in
|
|
this manual are in C. @xref{Languages, , Using @value{GDBN} with Different
|
|
Languages}, for information on how to use expressions in other
|
|
languages.
|
|
|
|
In this section, we discuss operators that you can use in @value{GDBN}
|
|
expressions regardless of your programming language.
|
|
|
|
@cindex casts, in expressions
|
|
Casts are supported in all languages, not just in C, because it is so
|
|
useful to cast a number into a pointer in order to examine a structure
|
|
at that address in memory.
|
|
@c FIXME: casts supported---Mod2 true?
|
|
|
|
@value{GDBN} supports these operators, in addition to those common
|
|
to programming languages:
|
|
|
|
@table @code
|
|
@item @@
|
|
@samp{@@} is a binary operator for treating parts of memory as arrays.
|
|
@xref{Arrays, ,Artificial Arrays}, for more information.
|
|
|
|
@item ::
|
|
@samp{::} allows you to specify a variable in terms of the file or
|
|
function where it is defined. @xref{Variables, ,Program Variables}.
|
|
|
|
@cindex @{@var{type}@}
|
|
@cindex type casting memory
|
|
@cindex memory, viewing as typed object
|
|
@cindex casts, to view memory
|
|
@item @{@var{type}@} @var{addr}
|
|
Refers to an object of type @var{type} stored at address @var{addr} in
|
|
memory. @var{addr} may be any expression whose value is an integer or
|
|
pointer (but parentheses are required around binary operators, just as in
|
|
a cast). This construct is allowed regardless of what kind of data is
|
|
normally supposed to reside at @var{addr}.
|
|
@end table
|
|
|
|
@node Ambiguous Expressions
|
|
@section Ambiguous Expressions
|
|
@cindex ambiguous expressions
|
|
|
|
Expressions can sometimes contain some ambiguous elements. For instance,
|
|
some programming languages (notably Ada, C@t{++} and Objective-C) permit
|
|
a single function name to be defined several times, for application in
|
|
different contexts. This is called @dfn{overloading}. Another example
|
|
involving Ada is generics. A @dfn{generic package} is similar to C@t{++}
|
|
templates and is typically instantiated several times, resulting in
|
|
the same function name being defined in different contexts.
|
|
|
|
In some cases and depending on the language, it is possible to adjust
|
|
the expression to remove the ambiguity. For instance in C@t{++}, you
|
|
can specify the signature of the function you want to break on, as in
|
|
@kbd{break @var{function}(@var{types})}. In Ada, using the fully
|
|
qualified name of your function often makes the expression unambiguous
|
|
as well.
|
|
|
|
When an ambiguity that needs to be resolved is detected, the debugger
|
|
has the capability to display a menu of numbered choices for each
|
|
possibility, and then waits for the selection with the prompt @samp{>}.
|
|
The first option is always @samp{[0] cancel}, and typing @kbd{0 @key{RET}}
|
|
aborts the current command. If the command in which the expression was
|
|
used allows more than one choice to be selected, the next option in the
|
|
menu is @samp{[1] all}, and typing @kbd{1 @key{RET}} selects all possible
|
|
choices.
|
|
|
|
For example, the following session excerpt shows an attempt to set a
|
|
breakpoint at the overloaded symbol @code{String::after}.
|
|
We choose three particular definitions of that function name:
|
|
|
|
@c FIXME! This is likely to change to show arg type lists, at least
|
|
@smallexample
|
|
@group
|
|
(@value{GDBP}) b String::after
|
|
[0] cancel
|
|
[1] all
|
|
[2] file:String.cc; line number:867
|
|
[3] file:String.cc; line number:860
|
|
[4] file:String.cc; line number:875
|
|
[5] file:String.cc; line number:853
|
|
[6] file:String.cc; line number:846
|
|
[7] file:String.cc; line number:735
|
|
> 2 4 6
|
|
Breakpoint 1 at 0xb26c: file String.cc, line 867.
|
|
Breakpoint 2 at 0xb344: file String.cc, line 875.
|
|
Breakpoint 3 at 0xafcc: file String.cc, line 846.
|
|
Multiple breakpoints were set.
|
|
Use the "delete" command to delete unwanted
|
|
breakpoints.
|
|
(@value{GDBP})
|
|
@end group
|
|
@end smallexample
|
|
|
|
@table @code
|
|
@kindex set multiple-symbols
|
|
@item set multiple-symbols @var{mode}
|
|
@cindex multiple-symbols menu
|
|
|
|
This option allows you to adjust the debugger behavior when an expression
|
|
is ambiguous.
|
|
|
|
By default, @var{mode} is set to @code{all}. If the command with which
|
|
the expression is used allows more than one choice, then @value{GDBN}
|
|
automatically selects all possible choices. For instance, inserting
|
|
a breakpoint on a function using an ambiguous name results in a breakpoint
|
|
inserted on each possible match. However, if a unique choice must be made,
|
|
then @value{GDBN} uses the menu to help you disambiguate the expression.
|
|
For instance, printing the address of an overloaded function will result
|
|
in the use of the menu.
|
|
|
|
When @var{mode} is set to @code{ask}, the debugger always uses the menu
|
|
when an ambiguity is detected.
|
|
|
|
Finally, when @var{mode} is set to @code{cancel}, the debugger reports
|
|
an error due to the ambiguity and the command is aborted.
|
|
|
|
@kindex show multiple-symbols
|
|
@item show multiple-symbols
|
|
Show the current value of the @code{multiple-symbols} setting.
|
|
@end table
|
|
|
|
@node Variables
|
|
@section Program Variables
|
|
|
|
The most common kind of expression to use is the name of a variable
|
|
in your program.
|
|
|
|
Variables in expressions are understood in the selected stack frame
|
|
(@pxref{Selection, ,Selecting a Frame}); they must be either:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
global (or file-static)
|
|
@end itemize
|
|
|
|
@noindent or
|
|
|
|
@itemize @bullet
|
|
@item
|
|
visible according to the scope rules of the
|
|
programming language from the point of execution in that frame
|
|
@end itemize
|
|
|
|
@noindent This means that in the function
|
|
|
|
@smallexample
|
|
foo (a)
|
|
int a;
|
|
@{
|
|
bar (a);
|
|
@{
|
|
int b = test ();
|
|
bar (b);
|
|
@}
|
|
@}
|
|
@end smallexample
|
|
|
|
@noindent
|
|
you can examine and use the variable @code{a} whenever your program is
|
|
executing within the function @code{foo}, but you can only use or
|
|
examine the variable @code{b} while your program is executing inside
|
|
the block where @code{b} is declared.
|
|
|
|
@cindex variable name conflict
|
|
There is an exception: you can refer to a variable or function whose
|
|
scope is a single source file even if the current execution point is not
|
|
in this file. But it is possible to have more than one such variable or
|
|
function with the same name (in different source files). If that
|
|
happens, referring to that name has unpredictable effects. If you wish,
|
|
you can specify a static variable in a particular function or file by
|
|
using the colon-colon (@code{::}) notation:
|
|
|
|
@cindex colon-colon, context for variables/functions
|
|
@ifnotinfo
|
|
@c info cannot cope with a :: index entry, but why deprive hard copy readers?
|
|
@cindex @code{::}, context for variables/functions
|
|
@end ifnotinfo
|
|
@smallexample
|
|
@var{file}::@var{variable}
|
|
@var{function}::@var{variable}
|
|
@end smallexample
|
|
|
|
@noindent
|
|
Here @var{file} or @var{function} is the name of the context for the
|
|
static @var{variable}. In the case of file names, you can use quotes to
|
|
make sure @value{GDBN} parses the file name as a single word---for example,
|
|
to print a global value of @code{x} defined in @file{f2.c}:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) p 'f2.c'::x
|
|
@end smallexample
|
|
|
|
The @code{::} notation is normally used for referring to
|
|
static variables, since you typically disambiguate uses of local variables
|
|
in functions by selecting the appropriate frame and using the
|
|
simple name of the variable. However, you may also use this notation
|
|
to refer to local variables in frames enclosing the selected frame:
|
|
|
|
@smallexample
|
|
void
|
|
foo (int a)
|
|
@{
|
|
if (a < 10)
|
|
bar (a);
|
|
else
|
|
process (a); /* Stop here */
|
|
@}
|
|
|
|
int
|
|
bar (int a)
|
|
@{
|
|
foo (a + 5);
|
|
@}
|
|
@end smallexample
|
|
|
|
@noindent
|
|
For example, if there is a breakpoint at the commented line,
|
|
here is what you might see
|
|
when the program stops after executing the call @code{bar(0)}:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) p a
|
|
$1 = 10
|
|
(@value{GDBP}) p bar::a
|
|
$2 = 5
|
|
(@value{GDBP}) up 2
|
|
#2 0x080483d0 in foo (a=5) at foobar.c:12
|
|
(@value{GDBP}) p a
|
|
$3 = 5
|
|
(@value{GDBP}) p bar::a
|
|
$4 = 0
|
|
@end smallexample
|
|
|
|
@cindex C@t{++} scope resolution
|
|
These uses of @samp{::} are very rarely in conflict with the very similar
|
|
use of the same notation in C@t{++}. @value{GDBN} also supports use of the C@t{++}
|
|
scope resolution operator in @value{GDBN} expressions.
|
|
@c FIXME: Um, so what happens in one of those rare cases where it's in
|
|
@c conflict?? --mew
|
|
|
|
@cindex wrong values
|
|
@cindex variable values, wrong
|
|
@cindex function entry/exit, wrong values of variables
|
|
@cindex optimized code, wrong values of variables
|
|
@quotation
|
|
@emph{Warning:} Occasionally, a local variable may appear to have the
|
|
wrong value at certain points in a function---just after entry to a new
|
|
scope, and just before exit.
|
|
@end quotation
|
|
You may see this problem when you are stepping by machine instructions.
|
|
This is because, on most machines, it takes more than one instruction to
|
|
set up a stack frame (including local variable definitions); if you are
|
|
stepping by machine instructions, variables may appear to have the wrong
|
|
values until the stack frame is completely built. On exit, it usually
|
|
also takes more than one machine instruction to destroy a stack frame;
|
|
after you begin stepping through that group of instructions, local
|
|
variable definitions may be gone.
|
|
|
|
This may also happen when the compiler does significant optimizations.
|
|
To be sure of always seeing accurate values, turn off all optimization
|
|
when compiling.
|
|
|
|
@cindex ``No symbol "foo" in current context''
|
|
Another possible effect of compiler optimizations is to optimize
|
|
unused variables out of existence, or assign variables to registers (as
|
|
opposed to memory addresses). Depending on the support for such cases
|
|
offered by the debug info format used by the compiler, @value{GDBN}
|
|
might not be able to display values for such local variables. If that
|
|
happens, @value{GDBN} will print a message like this:
|
|
|
|
@smallexample
|
|
No symbol "foo" in current context.
|
|
@end smallexample
|
|
|
|
To solve such problems, either recompile without optimizations, or use a
|
|
different debug info format, if the compiler supports several such
|
|
formats. @xref{Compilation}, for more information on choosing compiler
|
|
options. @xref{C, ,C and C@t{++}}, for more information about debug
|
|
info formats that are best suited to C@t{++} programs.
|
|
|
|
If you ask to print an object whose contents are unknown to
|
|
@value{GDBN}, e.g., because its data type is not completely specified
|
|
by the debug information, @value{GDBN} will say @samp{<incomplete
|
|
type>}. @xref{Symbols, incomplete type}, for more about this.
|
|
|
|
If you append @kbd{@@entry} string to a function parameter name you get its
|
|
value at the time the function got called. If the value is not available an
|
|
error message is printed. Entry values are available only with some compilers.
|
|
Entry values are normally also printed at the function parameter list according
|
|
to @ref{set print entry-values}.
|
|
|
|
@smallexample
|
|
Breakpoint 1, d (i=30) at gdb.base/entry-value.c:29
|
|
29 i++;
|
|
(gdb) next
|
|
30 e (i);
|
|
(gdb) print i
|
|
$1 = 31
|
|
(gdb) print i@@entry
|
|
$2 = 30
|
|
@end smallexample
|
|
|
|
Strings are identified as arrays of @code{char} values without specified
|
|
signedness. Arrays of either @code{signed char} or @code{unsigned char} get
|
|
printed as arrays of 1 byte sized integers. @code{-fsigned-char} or
|
|
@code{-funsigned-char} @value{NGCC} options have no effect as @value{GDBN}
|
|
defines literal string type @code{"char"} as @code{char} without a sign.
|
|
For program code
|
|
|
|
@smallexample
|
|
char var0[] = "A";
|
|
signed char var1[] = "A";
|
|
@end smallexample
|
|
|
|
You get during debugging
|
|
@smallexample
|
|
(gdb) print var0
|
|
$1 = "A"
|
|
(gdb) print var1
|
|
$2 = @{65 'A', 0 '\0'@}
|
|
@end smallexample
|
|
|
|
@node Arrays
|
|
@section Artificial Arrays
|
|
|
|
@cindex artificial array
|
|
@cindex arrays
|
|
@kindex @@@r{, referencing memory as an array}
|
|
It is often useful to print out several successive objects of the
|
|
same type in memory; a section of an array, or an array of
|
|
dynamically determined size for which only a pointer exists in the
|
|
program.
|
|
|
|
You can do this by referring to a contiguous span of memory as an
|
|
@dfn{artificial array}, using the binary operator @samp{@@}. The left
|
|
operand of @samp{@@} should be the first element of the desired array
|
|
and be an individual object. The right operand should be the desired length
|
|
of the array. The result is an array value whose elements are all of
|
|
the type of the left argument. The first element is actually the left
|
|
argument; the second element comes from bytes of memory immediately
|
|
following those that hold the first element, and so on. Here is an
|
|
example. If a program says
|
|
|
|
@smallexample
|
|
int *array = (int *) malloc (len * sizeof (int));
|
|
@end smallexample
|
|
|
|
@noindent
|
|
you can print the contents of @code{array} with
|
|
|
|
@smallexample
|
|
p *array@@len
|
|
@end smallexample
|
|
|
|
The left operand of @samp{@@} must reside in memory. Array values made
|
|
with @samp{@@} in this way behave just like other arrays in terms of
|
|
subscripting, and are coerced to pointers when used in expressions.
|
|
Artificial arrays most often appear in expressions via the value history
|
|
(@pxref{Value History, ,Value History}), after printing one out.
|
|
|
|
Another way to create an artificial array is to use a cast.
|
|
This re-interprets a value as if it were an array.
|
|
The value need not be in memory:
|
|
@smallexample
|
|
(@value{GDBP}) p/x (short[2])0x12345678
|
|
$1 = @{0x1234, 0x5678@}
|
|
@end smallexample
|
|
|
|
As a convenience, if you leave the array length out (as in
|
|
@samp{(@var{type}[])@var{value}}) @value{GDBN} calculates the size to fill
|
|
the value (as @samp{sizeof(@var{value})/sizeof(@var{type})}:
|
|
@smallexample
|
|
(@value{GDBP}) p/x (short[])0x12345678
|
|
$2 = @{0x1234, 0x5678@}
|
|
@end smallexample
|
|
|
|
Sometimes the artificial array mechanism is not quite enough; in
|
|
moderately complex data structures, the elements of interest may not
|
|
actually be adjacent---for example, if you are interested in the values
|
|
of pointers in an array. One useful work-around in this situation is
|
|
to use a convenience variable (@pxref{Convenience Vars, ,Convenience
|
|
Variables}) as a counter in an expression that prints the first
|
|
interesting value, and then repeat that expression via @key{RET}. For
|
|
instance, suppose you have an array @code{dtab} of pointers to
|
|
structures, and you are interested in the values of a field @code{fv}
|
|
in each structure. Here is an example of what you might type:
|
|
|
|
@smallexample
|
|
set $i = 0
|
|
p dtab[$i++]->fv
|
|
@key{RET}
|
|
@key{RET}
|
|
@dots{}
|
|
@end smallexample
|
|
|
|
@node Output Formats
|
|
@section Output Formats
|
|
|
|
@cindex formatted output
|
|
@cindex output formats
|
|
By default, @value{GDBN} prints a value according to its data type. Sometimes
|
|
this is not what you want. For example, you might want to print a number
|
|
in hex, or a pointer in decimal. Or you might want to view data in memory
|
|
at a certain address as a character string or as an instruction. To do
|
|
these things, specify an @dfn{output format} when you print a value.
|
|
|
|
The simplest use of output formats is to say how to print a value
|
|
already computed. This is done by starting the arguments of the
|
|
@code{print} command with a slash and a format letter. The format
|
|
letters supported are:
|
|
|
|
@table @code
|
|
@item x
|
|
Regard the bits of the value as an integer, and print the integer in
|
|
hexadecimal.
|
|
|
|
@item d
|
|
Print as integer in signed decimal.
|
|
|
|
@item u
|
|
Print as integer in unsigned decimal.
|
|
|
|
@item o
|
|
Print as integer in octal.
|
|
|
|
@item t
|
|
Print as integer in binary. The letter @samp{t} stands for ``two''.
|
|
@footnote{@samp{b} cannot be used because these format letters are also
|
|
used with the @code{x} command, where @samp{b} stands for ``byte'';
|
|
see @ref{Memory,,Examining Memory}.}
|
|
|
|
@item a
|
|
@cindex unknown address, locating
|
|
@cindex locate address
|
|
Print as an address, both absolute in hexadecimal and as an offset from
|
|
the nearest preceding symbol. You can use this format used to discover
|
|
where (in what function) an unknown address is located:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) p/a 0x54320
|
|
$3 = 0x54320 <_initialize_vx+396>
|
|
@end smallexample
|
|
|
|
@noindent
|
|
The command @code{info symbol 0x54320} yields similar results.
|
|
@xref{Symbols, info symbol}.
|
|
|
|
@item c
|
|
Regard as an integer and print it as a character constant. This
|
|
prints both the numerical value and its character representation. The
|
|
character representation is replaced with the octal escape @samp{\nnn}
|
|
for characters outside the 7-bit @sc{ascii} range.
|
|
|
|
Without this format, @value{GDBN} displays @code{char},
|
|
@w{@code{unsigned char}}, and @w{@code{signed char}} data as character
|
|
constants. Single-byte members of vectors are displayed as integer
|
|
data.
|
|
|
|
@item f
|
|
Regard the bits of the value as a floating point number and print
|
|
using typical floating point syntax.
|
|
|
|
@item s
|
|
@cindex printing strings
|
|
@cindex printing byte arrays
|
|
Regard as a string, if possible. With this format, pointers to single-byte
|
|
data are displayed as null-terminated strings and arrays of single-byte data
|
|
are displayed as fixed-length strings. Other values are displayed in their
|
|
natural types.
|
|
|
|
Without this format, @value{GDBN} displays pointers to and arrays of
|
|
@code{char}, @w{@code{unsigned char}}, and @w{@code{signed char}} as
|
|
strings. Single-byte members of a vector are displayed as an integer
|
|
array.
|
|
|
|
@item r
|
|
@cindex raw printing
|
|
Print using the @samp{raw} formatting. By default, @value{GDBN} will
|
|
use a Python-based pretty-printer, if one is available (@pxref{Pretty
|
|
Printing}). This typically results in a higher-level display of the
|
|
value's contents. The @samp{r} format bypasses any Python
|
|
pretty-printer which might exist.
|
|
@end table
|
|
|
|
For example, to print the program counter in hex (@pxref{Registers}), type
|
|
|
|
@smallexample
|
|
p/x $pc
|
|
@end smallexample
|
|
|
|
@noindent
|
|
Note that no space is required before the slash; this is because command
|
|
names in @value{GDBN} cannot contain a slash.
|
|
|
|
To reprint the last value in the value history with a different format,
|
|
you can use the @code{print} command with just a format and no
|
|
expression. For example, @samp{p/x} reprints the last value in hex.
|
|
|
|
@node Memory
|
|
@section Examining Memory
|
|
|
|
You can use the command @code{x} (for ``examine'') to examine memory in
|
|
any of several formats, independently of your program's data types.
|
|
|
|
@cindex examining memory
|
|
@table @code
|
|
@kindex x @r{(examine memory)}
|
|
@item x/@var{nfu} @var{addr}
|
|
@itemx x @var{addr}
|
|
@itemx x
|
|
Use the @code{x} command to examine memory.
|
|
@end table
|
|
|
|
@var{n}, @var{f}, and @var{u} are all optional parameters that specify how
|
|
much memory to display and how to format it; @var{addr} is an
|
|
expression giving the address where you want to start displaying memory.
|
|
If you use defaults for @var{nfu}, you need not type the slash @samp{/}.
|
|
Several commands set convenient defaults for @var{addr}.
|
|
|
|
@table @r
|
|
@item @var{n}, the repeat count
|
|
The repeat count is a decimal integer; the default is 1. It specifies
|
|
how much memory (counting by units @var{u}) to display.
|
|
@c This really is **decimal**; unaffected by 'set radix' as of GDB
|
|
@c 4.1.2.
|
|
|
|
@item @var{f}, the display format
|
|
The display format is one of the formats used by @code{print}
|
|
(@samp{x}, @samp{d}, @samp{u}, @samp{o}, @samp{t}, @samp{a}, @samp{c},
|
|
@samp{f}, @samp{s}), and in addition @samp{i} (for machine instructions).
|
|
The default is @samp{x} (hexadecimal) initially. The default changes
|
|
each time you use either @code{x} or @code{print}.
|
|
|
|
@item @var{u}, the unit size
|
|
The unit size is any of
|
|
|
|
@table @code
|
|
@item b
|
|
Bytes.
|
|
@item h
|
|
Halfwords (two bytes).
|
|
@item w
|
|
Words (four bytes). This is the initial default.
|
|
@item g
|
|
Giant words (eight bytes).
|
|
@end table
|
|
|
|
Each time you specify a unit size with @code{x}, that size becomes the
|
|
default unit the next time you use @code{x}. For the @samp{i} format,
|
|
the unit size is ignored and is normally not written. For the @samp{s} format,
|
|
the unit size defaults to @samp{b}, unless it is explicitly given.
|
|
Use @kbd{x /hs} to display 16-bit char strings and @kbd{x /ws} to display
|
|
32-bit strings. The next use of @kbd{x /s} will again display 8-bit strings.
|
|
Note that the results depend on the programming language of the
|
|
current compilation unit. If the language is C, the @samp{s}
|
|
modifier will use the UTF-16 encoding while @samp{w} will use
|
|
UTF-32. The encoding is set by the programming language and cannot
|
|
be altered.
|
|
|
|
@item @var{addr}, starting display address
|
|
@var{addr} is the address where you want @value{GDBN} to begin displaying
|
|
memory. The expression need not have a pointer value (though it may);
|
|
it is always interpreted as an integer address of a byte of memory.
|
|
@xref{Expressions, ,Expressions}, for more information on expressions. The default for
|
|
@var{addr} is usually just after the last address examined---but several
|
|
other commands also set the default address: @code{info breakpoints} (to
|
|
the address of the last breakpoint listed), @code{info line} (to the
|
|
starting address of a line), and @code{print} (if you use it to display
|
|
a value from memory).
|
|
@end table
|
|
|
|
For example, @samp{x/3uh 0x54320} is a request to display three halfwords
|
|
(@code{h}) of memory, formatted as unsigned decimal integers (@samp{u}),
|
|
starting at address @code{0x54320}. @samp{x/4xw $sp} prints the four
|
|
words (@samp{w}) of memory above the stack pointer (here, @samp{$sp};
|
|
@pxref{Registers, ,Registers}) in hexadecimal (@samp{x}).
|
|
|
|
Since the letters indicating unit sizes are all distinct from the
|
|
letters specifying output formats, you do not have to remember whether
|
|
unit size or format comes first; either order works. The output
|
|
specifications @samp{4xw} and @samp{4wx} mean exactly the same thing.
|
|
(However, the count @var{n} must come first; @samp{wx4} does not work.)
|
|
|
|
Even though the unit size @var{u} is ignored for the formats @samp{s}
|
|
and @samp{i}, you might still want to use a count @var{n}; for example,
|
|
@samp{3i} specifies that you want to see three machine instructions,
|
|
including any operands. For convenience, especially when used with
|
|
the @code{display} command, the @samp{i} format also prints branch delay
|
|
slot instructions, if any, beyond the count specified, which immediately
|
|
follow the last instruction that is within the count. The command
|
|
@code{disassemble} gives an alternative way of inspecting machine
|
|
instructions; see @ref{Machine Code,,Source and Machine Code}.
|
|
|
|
All the defaults for the arguments to @code{x} are designed to make it
|
|
easy to continue scanning memory with minimal specifications each time
|
|
you use @code{x}. For example, after you have inspected three machine
|
|
instructions with @samp{x/3i @var{addr}}, you can inspect the next seven
|
|
with just @samp{x/7}. If you use @key{RET} to repeat the @code{x} command,
|
|
the repeat count @var{n} is used again; the other arguments default as
|
|
for successive uses of @code{x}.
|
|
|
|
When examining machine instructions, the instruction at current program
|
|
counter is shown with a @code{=>} marker. For example:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) x/5i $pc-6
|
|
0x804837f <main+11>: mov %esp,%ebp
|
|
0x8048381 <main+13>: push %ecx
|
|
0x8048382 <main+14>: sub $0x4,%esp
|
|
=> 0x8048385 <main+17>: movl $0x8048460,(%esp)
|
|
0x804838c <main+24>: call 0x80482d4 <puts@@plt>
|
|
@end smallexample
|
|
|
|
@cindex @code{$_}, @code{$__}, and value history
|
|
The addresses and contents printed by the @code{x} command are not saved
|
|
in the value history because there is often too much of them and they
|
|
would get in the way. Instead, @value{GDBN} makes these values available for
|
|
subsequent use in expressions as values of the convenience variables
|
|
@code{$_} and @code{$__}. After an @code{x} command, the last address
|
|
examined is available for use in expressions in the convenience variable
|
|
@code{$_}. The contents of that address, as examined, are available in
|
|
the convenience variable @code{$__}.
|
|
|
|
If the @code{x} command has a repeat count, the address and contents saved
|
|
are from the last memory unit printed; this is not the same as the last
|
|
address printed if several units were printed on the last line of output.
|
|
|
|
@cindex remote memory comparison
|
|
@cindex verify remote memory image
|
|
When you are debugging a program running on a remote target machine
|
|
(@pxref{Remote Debugging}), you may wish to verify the program's image in the
|
|
remote machine's memory against the executable file you downloaded to
|
|
the target. The @code{compare-sections} command is provided for such
|
|
situations.
|
|
|
|
@table @code
|
|
@kindex compare-sections
|
|
@item compare-sections @r{[}@var{section-name}@r{]}
|
|
Compare the data of a loadable section @var{section-name} in the
|
|
executable file of the program being debugged with the same section in
|
|
the remote machine's memory, and report any mismatches. With no
|
|
arguments, compares all loadable sections. This command's
|
|
availability depends on the target's support for the @code{"qCRC"}
|
|
remote request.
|
|
@end table
|
|
|
|
@node Auto Display
|
|
@section Automatic Display
|
|
@cindex automatic display
|
|
@cindex display of expressions
|
|
|
|
If you find that you want to print the value of an expression frequently
|
|
(to see how it changes), you might want to add it to the @dfn{automatic
|
|
display list} so that @value{GDBN} prints its value each time your program stops.
|
|
Each expression added to the list is given a number to identify it;
|
|
to remove an expression from the list, you specify that number.
|
|
The automatic display looks like this:
|
|
|
|
@smallexample
|
|
2: foo = 38
|
|
3: bar[5] = (struct hack *) 0x3804
|
|
@end smallexample
|
|
|
|
@noindent
|
|
This display shows item numbers, expressions and their current values. As with
|
|
displays you request manually using @code{x} or @code{print}, you can
|
|
specify the output format you prefer; in fact, @code{display} decides
|
|
whether to use @code{print} or @code{x} depending your format
|
|
specification---it uses @code{x} if you specify either the @samp{i}
|
|
or @samp{s} format, or a unit size; otherwise it uses @code{print}.
|
|
|
|
@table @code
|
|
@kindex display
|
|
@item display @var{expr}
|
|
Add the expression @var{expr} to the list of expressions to display
|
|
each time your program stops. @xref{Expressions, ,Expressions}.
|
|
|
|
@code{display} does not repeat if you press @key{RET} again after using it.
|
|
|
|
@item display/@var{fmt} @var{expr}
|
|
For @var{fmt} specifying only a display format and not a size or
|
|
count, add the expression @var{expr} to the auto-display list but
|
|
arrange to display it each time in the specified format @var{fmt}.
|
|
@xref{Output Formats,,Output Formats}.
|
|
|
|
@item display/@var{fmt} @var{addr}
|
|
For @var{fmt} @samp{i} or @samp{s}, or including a unit-size or a
|
|
number of units, add the expression @var{addr} as a memory address to
|
|
be examined each time your program stops. Examining means in effect
|
|
doing @samp{x/@var{fmt} @var{addr}}. @xref{Memory, ,Examining Memory}.
|
|
@end table
|
|
|
|
For example, @samp{display/i $pc} can be helpful, to see the machine
|
|
instruction about to be executed each time execution stops (@samp{$pc}
|
|
is a common name for the program counter; @pxref{Registers, ,Registers}).
|
|
|
|
@table @code
|
|
@kindex delete display
|
|
@kindex undisplay
|
|
@item undisplay @var{dnums}@dots{}
|
|
@itemx delete display @var{dnums}@dots{}
|
|
Remove items from the list of expressions to display. Specify the
|
|
numbers of the displays that you want affected with the command
|
|
argument @var{dnums}. It can be a single display number, one of the
|
|
numbers shown in the first field of the @samp{info display} display;
|
|
or it could be a range of display numbers, as in @code{2-4}.
|
|
|
|
@code{undisplay} does not repeat if you press @key{RET} after using it.
|
|
(Otherwise you would just get the error @samp{No display number @dots{}}.)
|
|
|
|
@kindex disable display
|
|
@item disable display @var{dnums}@dots{}
|
|
Disable the display of item numbers @var{dnums}. A disabled display
|
|
item is not printed automatically, but is not forgotten. It may be
|
|
enabled again later. Specify the numbers of the displays that you
|
|
want affected with the command argument @var{dnums}. It can be a
|
|
single display number, one of the numbers shown in the first field of
|
|
the @samp{info display} display; or it could be a range of display
|
|
numbers, as in @code{2-4}.
|
|
|
|
@kindex enable display
|
|
@item enable display @var{dnums}@dots{}
|
|
Enable display of item numbers @var{dnums}. It becomes effective once
|
|
again in auto display of its expression, until you specify otherwise.
|
|
Specify the numbers of the displays that you want affected with the
|
|
command argument @var{dnums}. It can be a single display number, one
|
|
of the numbers shown in the first field of the @samp{info display}
|
|
display; or it could be a range of display numbers, as in @code{2-4}.
|
|
|
|
@item display
|
|
Display the current values of the expressions on the list, just as is
|
|
done when your program stops.
|
|
|
|
@kindex info display
|
|
@item info display
|
|
Print the list of expressions previously set up to display
|
|
automatically, each one with its item number, but without showing the
|
|
values. This includes disabled expressions, which are marked as such.
|
|
It also includes expressions which would not be displayed right now
|
|
because they refer to automatic variables not currently available.
|
|
@end table
|
|
|
|
@cindex display disabled out of scope
|
|
If a display expression refers to local variables, then it does not make
|
|
sense outside the lexical context for which it was set up. Such an
|
|
expression is disabled when execution enters a context where one of its
|
|
variables is not defined. For example, if you give the command
|
|
@code{display last_char} while inside a function with an argument
|
|
@code{last_char}, @value{GDBN} displays this argument while your program
|
|
continues to stop inside that function. When it stops elsewhere---where
|
|
there is no variable @code{last_char}---the display is disabled
|
|
automatically. The next time your program stops where @code{last_char}
|
|
is meaningful, you can enable the display expression once again.
|
|
|
|
@node Print Settings
|
|
@section Print Settings
|
|
|
|
@cindex format options
|
|
@cindex print settings
|
|
@value{GDBN} provides the following ways to control how arrays, structures,
|
|
and symbols are printed.
|
|
|
|
@noindent
|
|
These settings are useful for debugging programs in any language:
|
|
|
|
@table @code
|
|
@kindex set print
|
|
@item set print address
|
|
@itemx set print address on
|
|
@cindex print/don't print memory addresses
|
|
@value{GDBN} prints memory addresses showing the location of stack
|
|
traces, structure values, pointer values, breakpoints, and so forth,
|
|
even when it also displays the contents of those addresses. The default
|
|
is @code{on}. For example, this is what a stack frame display looks like with
|
|
@code{set print address on}:
|
|
|
|
@smallexample
|
|
@group
|
|
(@value{GDBP}) f
|
|
#0 set_quotes (lq=0x34c78 "<<", rq=0x34c88 ">>")
|
|
at input.c:530
|
|
530 if (lquote != def_lquote)
|
|
@end group
|
|
@end smallexample
|
|
|
|
@item set print address off
|
|
Do not print addresses when displaying their contents. For example,
|
|
this is the same stack frame displayed with @code{set print address off}:
|
|
|
|
@smallexample
|
|
@group
|
|
(@value{GDBP}) set print addr off
|
|
(@value{GDBP}) f
|
|
#0 set_quotes (lq="<<", rq=">>") at input.c:530
|
|
530 if (lquote != def_lquote)
|
|
@end group
|
|
@end smallexample
|
|
|
|
You can use @samp{set print address off} to eliminate all machine
|
|
dependent displays from the @value{GDBN} interface. For example, with
|
|
@code{print address off}, you should get the same text for backtraces on
|
|
all machines---whether or not they involve pointer arguments.
|
|
|
|
@kindex show print
|
|
@item show print address
|
|
Show whether or not addresses are to be printed.
|
|
@end table
|
|
|
|
When @value{GDBN} prints a symbolic address, it normally prints the
|
|
closest earlier symbol plus an offset. If that symbol does not uniquely
|
|
identify the address (for example, it is a name whose scope is a single
|
|
source file), you may need to clarify. One way to do this is with
|
|
@code{info line}, for example @samp{info line *0x4537}. Alternately,
|
|
you can set @value{GDBN} to print the source file and line number when
|
|
it prints a symbolic address:
|
|
|
|
@table @code
|
|
@item set print symbol-filename on
|
|
@cindex source file and line of a symbol
|
|
@cindex symbol, source file and line
|
|
Tell @value{GDBN} to print the source file name and line number of a
|
|
symbol in the symbolic form of an address.
|
|
|
|
@item set print symbol-filename off
|
|
Do not print source file name and line number of a symbol. This is the
|
|
default.
|
|
|
|
@item show print symbol-filename
|
|
Show whether or not @value{GDBN} will print the source file name and
|
|
line number of a symbol in the symbolic form of an address.
|
|
@end table
|
|
|
|
Another situation where it is helpful to show symbol filenames and line
|
|
numbers is when disassembling code; @value{GDBN} shows you the line
|
|
number and source file that corresponds to each instruction.
|
|
|
|
Also, you may wish to see the symbolic form only if the address being
|
|
printed is reasonably close to the closest earlier symbol:
|
|
|
|
@table @code
|
|
@item set print max-symbolic-offset @var{max-offset}
|
|
@cindex maximum value for offset of closest symbol
|
|
Tell @value{GDBN} to only display the symbolic form of an address if the
|
|
offset between the closest earlier symbol and the address is less than
|
|
@var{max-offset}. The default is 0, which tells @value{GDBN}
|
|
to always print the symbolic form of an address if any symbol precedes it.
|
|
|
|
@item show print max-symbolic-offset
|
|
Ask how large the maximum offset is that @value{GDBN} prints in a
|
|
symbolic address.
|
|
@end table
|
|
|
|
@cindex wild pointer, interpreting
|
|
@cindex pointer, finding referent
|
|
If you have a pointer and you are not sure where it points, try
|
|
@samp{set print symbol-filename on}. Then you can determine the name
|
|
and source file location of the variable where it points, using
|
|
@samp{p/a @var{pointer}}. This interprets the address in symbolic form.
|
|
For example, here @value{GDBN} shows that a variable @code{ptt} points
|
|
at another variable @code{t}, defined in @file{hi2.c}:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) set print symbol-filename on
|
|
(@value{GDBP}) p/a ptt
|
|
$4 = 0xe008 <t in hi2.c>
|
|
@end smallexample
|
|
|
|
@quotation
|
|
@emph{Warning:} For pointers that point to a local variable, @samp{p/a}
|
|
does not show the symbol name and filename of the referent, even with
|
|
the appropriate @code{set print} options turned on.
|
|
@end quotation
|
|
|
|
You can also enable @samp{/a}-like formatting all the time using
|
|
@samp{set print symbol on}:
|
|
|
|
@table @code
|
|
@item set print symbol on
|
|
Tell @value{GDBN} to print the symbol corresponding to an address, if
|
|
one exists.
|
|
|
|
@item set print symbol off
|
|
Tell @value{GDBN} not to print the symbol corresponding to an
|
|
address. In this mode, @value{GDBN} will still print the symbol
|
|
corresponding to pointers to functions. This is the default.
|
|
|
|
@item show print symbol
|
|
Show whether @value{GDBN} will display the symbol corresponding to an
|
|
address.
|
|
@end table
|
|
|
|
Other settings control how different kinds of objects are printed:
|
|
|
|
@table @code
|
|
@item set print array
|
|
@itemx set print array on
|
|
@cindex pretty print arrays
|
|
Pretty print arrays. This format is more convenient to read,
|
|
but uses more space. The default is off.
|
|
|
|
@item set print array off
|
|
Return to compressed format for arrays.
|
|
|
|
@item show print array
|
|
Show whether compressed or pretty format is selected for displaying
|
|
arrays.
|
|
|
|
@cindex print array indexes
|
|
@item set print array-indexes
|
|
@itemx set print array-indexes on
|
|
Print the index of each element when displaying arrays. May be more
|
|
convenient to locate a given element in the array or quickly find the
|
|
index of a given element in that printed array. The default is off.
|
|
|
|
@item set print array-indexes off
|
|
Stop printing element indexes when displaying arrays.
|
|
|
|
@item show print array-indexes
|
|
Show whether the index of each element is printed when displaying
|
|
arrays.
|
|
|
|
@item set print elements @var{number-of-elements}
|
|
@cindex number of array elements to print
|
|
@cindex limit on number of printed array elements
|
|
Set a limit on how many elements of an array @value{GDBN} will print.
|
|
If @value{GDBN} is printing a large array, it stops printing after it has
|
|
printed the number of elements set by the @code{set print elements} command.
|
|
This limit also applies to the display of strings.
|
|
When @value{GDBN} starts, this limit is set to 200.
|
|
Setting @var{number-of-elements} to zero means that the printing is unlimited.
|
|
|
|
@item show print elements
|
|
Display the number of elements of a large array that @value{GDBN} will print.
|
|
If the number is 0, then the printing is unlimited.
|
|
|
|
@item set print frame-arguments @var{value}
|
|
@kindex set print frame-arguments
|
|
@cindex printing frame argument values
|
|
@cindex print all frame argument values
|
|
@cindex print frame argument values for scalars only
|
|
@cindex do not print frame argument values
|
|
This command allows to control how the values of arguments are printed
|
|
when the debugger prints a frame (@pxref{Frames}). The possible
|
|
values are:
|
|
|
|
@table @code
|
|
@item all
|
|
The values of all arguments are printed.
|
|
|
|
@item scalars
|
|
Print the value of an argument only if it is a scalar. The value of more
|
|
complex arguments such as arrays, structures, unions, etc, is replaced
|
|
by @code{@dots{}}. This is the default. Here is an example where
|
|
only scalar arguments are shown:
|
|
|
|
@smallexample
|
|
#1 0x08048361 in call_me (i=3, s=@dots{}, ss=0xbf8d508c, u=@dots{}, e=green)
|
|
at frame-args.c:23
|
|
@end smallexample
|
|
|
|
@item none
|
|
None of the argument values are printed. Instead, the value of each argument
|
|
is replaced by @code{@dots{}}. In this case, the example above now becomes:
|
|
|
|
@smallexample
|
|
#1 0x08048361 in call_me (i=@dots{}, s=@dots{}, ss=@dots{}, u=@dots{}, e=@dots{})
|
|
at frame-args.c:23
|
|
@end smallexample
|
|
@end table
|
|
|
|
By default, only scalar arguments are printed. This command can be used
|
|
to configure the debugger to print the value of all arguments, regardless
|
|
of their type. However, it is often advantageous to not print the value
|
|
of more complex parameters. For instance, it reduces the amount of
|
|
information printed in each frame, making the backtrace more readable.
|
|
Also, it improves performance when displaying Ada frames, because
|
|
the computation of large arguments can sometimes be CPU-intensive,
|
|
especially in large applications. Setting @code{print frame-arguments}
|
|
to @code{scalars} (the default) or @code{none} avoids this computation,
|
|
thus speeding up the display of each Ada frame.
|
|
|
|
@item show print frame-arguments
|
|
Show how the value of arguments should be displayed when printing a frame.
|
|
|
|
@anchor{set print entry-values}
|
|
@item set print entry-values @var{value}
|
|
@kindex set print entry-values
|
|
Set printing of frame argument values at function entry. In some cases
|
|
@value{GDBN} can determine the value of function argument which was passed by
|
|
the function caller, even if the value was modified inside the called function
|
|
and therefore is different. With optimized code, the current value could be
|
|
unavailable, but the entry value may still be known.
|
|
|
|
The default value is @code{default} (see below for its description). Older
|
|
@value{GDBN} behaved as with the setting @code{no}. Compilers not supporting
|
|
this feature will behave in the @code{default} setting the same way as with the
|
|
@code{no} setting.
|
|
|
|
This functionality is currently supported only by DWARF 2 debugging format and
|
|
the compiler has to produce @samp{DW_TAG_GNU_call_site} tags. With
|
|
@value{NGCC}, you need to specify @option{-O -g} during compilation, to get
|
|
this information.
|
|
|
|
The @var{value} parameter can be one of the following:
|
|
|
|
@table @code
|
|
@item no
|
|
Print only actual parameter values, never print values from function entry
|
|
point.
|
|
@smallexample
|
|
#0 equal (val=5)
|
|
#0 different (val=6)
|
|
#0 lost (val=<optimized out>)
|
|
#0 born (val=10)
|
|
#0 invalid (val=<optimized out>)
|
|
@end smallexample
|
|
|
|
@item only
|
|
Print only parameter values from function entry point. The actual parameter
|
|
values are never printed.
|
|
@smallexample
|
|
#0 equal (val@@entry=5)
|
|
#0 different (val@@entry=5)
|
|
#0 lost (val@@entry=5)
|
|
#0 born (val@@entry=<optimized out>)
|
|
#0 invalid (val@@entry=<optimized out>)
|
|
@end smallexample
|
|
|
|
@item preferred
|
|
Print only parameter values from function entry point. If value from function
|
|
entry point is not known while the actual value is known, print the actual
|
|
value for such parameter.
|
|
@smallexample
|
|
#0 equal (val@@entry=5)
|
|
#0 different (val@@entry=5)
|
|
#0 lost (val@@entry=5)
|
|
#0 born (val=10)
|
|
#0 invalid (val@@entry=<optimized out>)
|
|
@end smallexample
|
|
|
|
@item if-needed
|
|
Print actual parameter values. If actual parameter value is not known while
|
|
value from function entry point is known, print the entry point value for such
|
|
parameter.
|
|
@smallexample
|
|
#0 equal (val=5)
|
|
#0 different (val=6)
|
|
#0 lost (val@@entry=5)
|
|
#0 born (val=10)
|
|
#0 invalid (val=<optimized out>)
|
|
@end smallexample
|
|
|
|
@item both
|
|
Always print both the actual parameter value and its value from function entry
|
|
point, even if values of one or both are not available due to compiler
|
|
optimizations.
|
|
@smallexample
|
|
#0 equal (val=5, val@@entry=5)
|
|
#0 different (val=6, val@@entry=5)
|
|
#0 lost (val=<optimized out>, val@@entry=5)
|
|
#0 born (val=10, val@@entry=<optimized out>)
|
|
#0 invalid (val=<optimized out>, val@@entry=<optimized out>)
|
|
@end smallexample
|
|
|
|
@item compact
|
|
Print the actual parameter value if it is known and also its value from
|
|
function entry point if it is known. If neither is known, print for the actual
|
|
value @code{<optimized out>}. If not in MI mode (@pxref{GDB/MI}) and if both
|
|
values are known and identical, print the shortened
|
|
@code{param=param@@entry=VALUE} notation.
|
|
@smallexample
|
|
#0 equal (val=val@@entry=5)
|
|
#0 different (val=6, val@@entry=5)
|
|
#0 lost (val@@entry=5)
|
|
#0 born (val=10)
|
|
#0 invalid (val=<optimized out>)
|
|
@end smallexample
|
|
|
|
@item default
|
|
Always print the actual parameter value. Print also its value from function
|
|
entry point, but only if it is known. If not in MI mode (@pxref{GDB/MI}) and
|
|
if both values are known and identical, print the shortened
|
|
@code{param=param@@entry=VALUE} notation.
|
|
@smallexample
|
|
#0 equal (val=val@@entry=5)
|
|
#0 different (val=6, val@@entry=5)
|
|
#0 lost (val=<optimized out>, val@@entry=5)
|
|
#0 born (val=10)
|
|
#0 invalid (val=<optimized out>)
|
|
@end smallexample
|
|
@end table
|
|
|
|
For analysis messages on possible failures of frame argument values at function
|
|
entry resolution see @ref{set debug entry-values}.
|
|
|
|
@item show print entry-values
|
|
Show the method being used for printing of frame argument values at function
|
|
entry.
|
|
|
|
@item set print repeats
|
|
@cindex repeated array elements
|
|
Set the threshold for suppressing display of repeated array
|
|
elements. When the number of consecutive identical elements of an
|
|
array exceeds the threshold, @value{GDBN} prints the string
|
|
@code{"<repeats @var{n} times>"}, where @var{n} is the number of
|
|
identical repetitions, instead of displaying the identical elements
|
|
themselves. Setting the threshold to zero will cause all elements to
|
|
be individually printed. The default threshold is 10.
|
|
|
|
@item show print repeats
|
|
Display the current threshold for printing repeated identical
|
|
elements.
|
|
|
|
@item set print null-stop
|
|
@cindex @sc{null} elements in arrays
|
|
Cause @value{GDBN} to stop printing the characters of an array when the first
|
|
@sc{null} is encountered. This is useful when large arrays actually
|
|
contain only short strings.
|
|
The default is off.
|
|
|
|
@item show print null-stop
|
|
Show whether @value{GDBN} stops printing an array on the first
|
|
@sc{null} character.
|
|
|
|
@item set print pretty on
|
|
@cindex print structures in indented form
|
|
@cindex indentation in structure display
|
|
Cause @value{GDBN} to print structures in an indented format with one member
|
|
per line, like this:
|
|
|
|
@smallexample
|
|
@group
|
|
$1 = @{
|
|
next = 0x0,
|
|
flags = @{
|
|
sweet = 1,
|
|
sour = 1
|
|
@},
|
|
meat = 0x54 "Pork"
|
|
@}
|
|
@end group
|
|
@end smallexample
|
|
|
|
@item set print pretty off
|
|
Cause @value{GDBN} to print structures in a compact format, like this:
|
|
|
|
@smallexample
|
|
@group
|
|
$1 = @{next = 0x0, flags = @{sweet = 1, sour = 1@}, \
|
|
meat = 0x54 "Pork"@}
|
|
@end group
|
|
@end smallexample
|
|
|
|
@noindent
|
|
This is the default format.
|
|
|
|
@item show print pretty
|
|
Show which format @value{GDBN} is using to print structures.
|
|
|
|
@item set print sevenbit-strings on
|
|
@cindex eight-bit characters in strings
|
|
@cindex octal escapes in strings
|
|
Print using only seven-bit characters; if this option is set,
|
|
@value{GDBN} displays any eight-bit characters (in strings or
|
|
character values) using the notation @code{\}@var{nnn}. This setting is
|
|
best if you are working in English (@sc{ascii}) and you use the
|
|
high-order bit of characters as a marker or ``meta'' bit.
|
|
|
|
@item set print sevenbit-strings off
|
|
Print full eight-bit characters. This allows the use of more
|
|
international character sets, and is the default.
|
|
|
|
@item show print sevenbit-strings
|
|
Show whether or not @value{GDBN} is printing only seven-bit characters.
|
|
|
|
@item set print union on
|
|
@cindex unions in structures, printing
|
|
Tell @value{GDBN} to print unions which are contained in structures
|
|
and other unions. This is the default setting.
|
|
|
|
@item set print union off
|
|
Tell @value{GDBN} not to print unions which are contained in
|
|
structures and other unions. @value{GDBN} will print @code{"@{...@}"}
|
|
instead.
|
|
|
|
@item show print union
|
|
Ask @value{GDBN} whether or not it will print unions which are contained in
|
|
structures and other unions.
|
|
|
|
For example, given the declarations
|
|
|
|
@smallexample
|
|
typedef enum @{Tree, Bug@} Species;
|
|
typedef enum @{Big_tree, Acorn, Seedling@} Tree_forms;
|
|
typedef enum @{Caterpillar, Cocoon, Butterfly@}
|
|
Bug_forms;
|
|
|
|
struct thing @{
|
|
Species it;
|
|
union @{
|
|
Tree_forms tree;
|
|
Bug_forms bug;
|
|
@} form;
|
|
@};
|
|
|
|
struct thing foo = @{Tree, @{Acorn@}@};
|
|
@end smallexample
|
|
|
|
@noindent
|
|
with @code{set print union on} in effect @samp{p foo} would print
|
|
|
|
@smallexample
|
|
$1 = @{it = Tree, form = @{tree = Acorn, bug = Cocoon@}@}
|
|
@end smallexample
|
|
|
|
@noindent
|
|
and with @code{set print union off} in effect it would print
|
|
|
|
@smallexample
|
|
$1 = @{it = Tree, form = @{...@}@}
|
|
@end smallexample
|
|
|
|
@noindent
|
|
@code{set print union} affects programs written in C-like languages
|
|
and in Pascal.
|
|
@end table
|
|
|
|
@need 1000
|
|
@noindent
|
|
These settings are of interest when debugging C@t{++} programs:
|
|
|
|
@table @code
|
|
@cindex demangling C@t{++} names
|
|
@item set print demangle
|
|
@itemx set print demangle on
|
|
Print C@t{++} names in their source form rather than in the encoded
|
|
(``mangled'') form passed to the assembler and linker for type-safe
|
|
linkage. The default is on.
|
|
|
|
@item show print demangle
|
|
Show whether C@t{++} names are printed in mangled or demangled form.
|
|
|
|
@item set print asm-demangle
|
|
@itemx set print asm-demangle on
|
|
Print C@t{++} names in their source form rather than their mangled form, even
|
|
in assembler code printouts such as instruction disassemblies.
|
|
The default is off.
|
|
|
|
@item show print asm-demangle
|
|
Show whether C@t{++} names in assembly listings are printed in mangled
|
|
or demangled form.
|
|
|
|
@cindex C@t{++} symbol decoding style
|
|
@cindex symbol decoding style, C@t{++}
|
|
@kindex set demangle-style
|
|
@item set demangle-style @var{style}
|
|
Choose among several encoding schemes used by different compilers to
|
|
represent C@t{++} names. The choices for @var{style} are currently:
|
|
|
|
@table @code
|
|
@item auto
|
|
Allow @value{GDBN} to choose a decoding style by inspecting your program.
|
|
|
|
@item gnu
|
|
Decode based on the @sc{gnu} C@t{++} compiler (@code{g++}) encoding algorithm.
|
|
This is the default.
|
|
|
|
@item hp
|
|
Decode based on the HP ANSI C@t{++} (@code{aCC}) encoding algorithm.
|
|
|
|
@item lucid
|
|
Decode based on the Lucid C@t{++} compiler (@code{lcc}) encoding algorithm.
|
|
|
|
@item arm
|
|
Decode using the algorithm in the @cite{C@t{++} Annotated Reference Manual}.
|
|
@strong{Warning:} this setting alone is not sufficient to allow
|
|
debugging @code{cfront}-generated executables. @value{GDBN} would
|
|
require further enhancement to permit that.
|
|
|
|
@end table
|
|
If you omit @var{style}, you will see a list of possible formats.
|
|
|
|
@item show demangle-style
|
|
Display the encoding style currently in use for decoding C@t{++} symbols.
|
|
|
|
@item set print object
|
|
@itemx set print object on
|
|
@cindex derived type of an object, printing
|
|
@cindex display derived types
|
|
When displaying a pointer to an object, identify the @emph{actual}
|
|
(derived) type of the object rather than the @emph{declared} type, using
|
|
the virtual function table. Note that the virtual function table is
|
|
required---this feature can only work for objects that have run-time
|
|
type identification; a single virtual method in the object's declared
|
|
type is sufficient. Note that this setting is also taken into account when
|
|
working with variable objects via MI (@pxref{GDB/MI}).
|
|
|
|
@item set print object off
|
|
Display only the declared type of objects, without reference to the
|
|
virtual function table. This is the default setting.
|
|
|
|
@item show print object
|
|
Show whether actual, or declared, object types are displayed.
|
|
|
|
@item set print static-members
|
|
@itemx set print static-members on
|
|
@cindex static members of C@t{++} objects
|
|
Print static members when displaying a C@t{++} object. The default is on.
|
|
|
|
@item set print static-members off
|
|
Do not print static members when displaying a C@t{++} object.
|
|
|
|
@item show print static-members
|
|
Show whether C@t{++} static members are printed or not.
|
|
|
|
@item set print pascal_static-members
|
|
@itemx set print pascal_static-members on
|
|
@cindex static members of Pascal objects
|
|
@cindex Pascal objects, static members display
|
|
Print static members when displaying a Pascal object. The default is on.
|
|
|
|
@item set print pascal_static-members off
|
|
Do not print static members when displaying a Pascal object.
|
|
|
|
@item show print pascal_static-members
|
|
Show whether Pascal static members are printed or not.
|
|
|
|
@c These don't work with HP ANSI C++ yet.
|
|
@item set print vtbl
|
|
@itemx set print vtbl on
|
|
@cindex pretty print C@t{++} virtual function tables
|
|
@cindex virtual functions (C@t{++}) display
|
|
@cindex VTBL display
|
|
Pretty print C@t{++} virtual function tables. The default is off.
|
|
(The @code{vtbl} commands do not work on programs compiled with the HP
|
|
ANSI C@t{++} compiler (@code{aCC}).)
|
|
|
|
@item set print vtbl off
|
|
Do not pretty print C@t{++} virtual function tables.
|
|
|
|
@item show print vtbl
|
|
Show whether C@t{++} virtual function tables are pretty printed, or not.
|
|
@end table
|
|
|
|
@node Pretty Printing
|
|
@section Pretty Printing
|
|
|
|
@value{GDBN} provides a mechanism to allow pretty-printing of values using
|
|
Python code. It greatly simplifies the display of complex objects. This
|
|
mechanism works for both MI and the CLI.
|
|
|
|
@menu
|
|
* Pretty-Printer Introduction:: Introduction to pretty-printers
|
|
* Pretty-Printer Example:: An example pretty-printer
|
|
* Pretty-Printer Commands:: Pretty-printer commands
|
|
@end menu
|
|
|
|
@node Pretty-Printer Introduction
|
|
@subsection Pretty-Printer Introduction
|
|
|
|
When @value{GDBN} prints a value, it first sees if there is a pretty-printer
|
|
registered for the value. If there is then @value{GDBN} invokes the
|
|
pretty-printer to print the value. Otherwise the value is printed normally.
|
|
|
|
Pretty-printers are normally named. This makes them easy to manage.
|
|
The @samp{info pretty-printer} command will list all the installed
|
|
pretty-printers with their names.
|
|
If a pretty-printer can handle multiple data types, then its
|
|
@dfn{subprinters} are the printers for the individual data types.
|
|
Each such subprinter has its own name.
|
|
The format of the name is @var{printer-name};@var{subprinter-name}.
|
|
|
|
Pretty-printers are installed by @dfn{registering} them with @value{GDBN}.
|
|
Typically they are automatically loaded and registered when the corresponding
|
|
debug information is loaded, thus making them available without having to
|
|
do anything special.
|
|
|
|
There are three places where a pretty-printer can be registered.
|
|
|
|
@itemize @bullet
|
|
@item
|
|
Pretty-printers registered globally are available when debugging
|
|
all inferiors.
|
|
|
|
@item
|
|
Pretty-printers registered with a program space are available only
|
|
when debugging that program.
|
|
@xref{Progspaces In Python}, for more details on program spaces in Python.
|
|
|
|
@item
|
|
Pretty-printers registered with an objfile are loaded and unloaded
|
|
with the corresponding objfile (e.g., shared library).
|
|
@xref{Objfiles In Python}, for more details on objfiles in Python.
|
|
@end itemize
|
|
|
|
@xref{Selecting Pretty-Printers}, for further information on how
|
|
pretty-printers are selected,
|
|
|
|
@xref{Writing a Pretty-Printer}, for implementing pretty printers
|
|
for new types.
|
|
|
|
@node Pretty-Printer Example
|
|
@subsection Pretty-Printer Example
|
|
|
|
Here is how a C@t{++} @code{std::string} looks without a pretty-printer:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) print s
|
|
$1 = @{
|
|
static npos = 4294967295,
|
|
_M_dataplus = @{
|
|
<std::allocator<char>> = @{
|
|
<__gnu_cxx::new_allocator<char>> = @{
|
|
<No data fields>@}, <No data fields>
|
|
@},
|
|
members of std::basic_string<char, std::char_traits<char>,
|
|
std::allocator<char> >::_Alloc_hider:
|
|
_M_p = 0x804a014 "abcd"
|
|
@}
|
|
@}
|
|
@end smallexample
|
|
|
|
With a pretty-printer for @code{std::string} only the contents are printed:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) print s
|
|
$2 = "abcd"
|
|
@end smallexample
|
|
|
|
@node Pretty-Printer Commands
|
|
@subsection Pretty-Printer Commands
|
|
@cindex pretty-printer commands
|
|
|
|
@table @code
|
|
@kindex info pretty-printer
|
|
@item info pretty-printer [@var{object-regexp} [@var{name-regexp}]]
|
|
Print the list of installed pretty-printers.
|
|
This includes disabled pretty-printers, which are marked as such.
|
|
|
|
@var{object-regexp} is a regular expression matching the objects
|
|
whose pretty-printers to list.
|
|
Objects can be @code{global}, the program space's file
|
|
(@pxref{Progspaces In Python}),
|
|
and the object files within that program space (@pxref{Objfiles In Python}).
|
|
@xref{Selecting Pretty-Printers}, for details on how @value{GDBN}
|
|
looks up a printer from these three objects.
|
|
|
|
@var{name-regexp} is a regular expression matching the name of the printers
|
|
to list.
|
|
|
|
@kindex disable pretty-printer
|
|
@item disable pretty-printer [@var{object-regexp} [@var{name-regexp}]]
|
|
Disable pretty-printers matching @var{object-regexp} and @var{name-regexp}.
|
|
A disabled pretty-printer is not forgotten, it may be enabled again later.
|
|
|
|
@kindex enable pretty-printer
|
|
@item enable pretty-printer [@var{object-regexp} [@var{name-regexp}]]
|
|
Enable pretty-printers matching @var{object-regexp} and @var{name-regexp}.
|
|
@end table
|
|
|
|
Example:
|
|
|
|
Suppose we have three pretty-printers installed: one from library1.so
|
|
named @code{foo} that prints objects of type @code{foo}, and
|
|
another from library2.so named @code{bar} that prints two types of objects,
|
|
@code{bar1} and @code{bar2}.
|
|
|
|
@smallexample
|
|
(gdb) info pretty-printer
|
|
library1.so:
|
|
foo
|
|
library2.so:
|
|
bar
|
|
bar1
|
|
bar2
|
|
(gdb) info pretty-printer library2
|
|
library2.so:
|
|
bar
|
|
bar1
|
|
bar2
|
|
(gdb) disable pretty-printer library1
|
|
1 printer disabled
|
|
2 of 3 printers enabled
|
|
(gdb) info pretty-printer
|
|
library1.so:
|
|
foo [disabled]
|
|
library2.so:
|
|
bar
|
|
bar1
|
|
bar2
|
|
(gdb) disable pretty-printer library2 bar:bar1
|
|
1 printer disabled
|
|
1 of 3 printers enabled
|
|
(gdb) info pretty-printer library2
|
|
library1.so:
|
|
foo [disabled]
|
|
library2.so:
|
|
bar
|
|
bar1 [disabled]
|
|
bar2
|
|
(gdb) disable pretty-printer library2 bar
|
|
1 printer disabled
|
|
0 of 3 printers enabled
|
|
(gdb) info pretty-printer library2
|
|
library1.so:
|
|
foo [disabled]
|
|
library2.so:
|
|
bar [disabled]
|
|
bar1 [disabled]
|
|
bar2
|
|
@end smallexample
|
|
|
|
Note that for @code{bar} the entire printer can be disabled,
|
|
as can each individual subprinter.
|
|
|
|
@node Value History
|
|
@section Value History
|
|
|
|
@cindex value history
|
|
@cindex history of values printed by @value{GDBN}
|
|
Values printed by the @code{print} command are saved in the @value{GDBN}
|
|
@dfn{value history}. This allows you to refer to them in other expressions.
|
|
Values are kept until the symbol table is re-read or discarded
|
|
(for example with the @code{file} or @code{symbol-file} commands).
|
|
When the symbol table changes, the value history is discarded,
|
|
since the values may contain pointers back to the types defined in the
|
|
symbol table.
|
|
|
|
@cindex @code{$}
|
|
@cindex @code{$$}
|
|
@cindex history number
|
|
The values printed are given @dfn{history numbers} by which you can
|
|
refer to them. These are successive integers starting with one.
|
|
@code{print} shows you the history number assigned to a value by
|
|
printing @samp{$@var{num} = } before the value; here @var{num} is the
|
|
history number.
|
|
|
|
To refer to any previous value, use @samp{$} followed by the value's
|
|
history number. The way @code{print} labels its output is designed to
|
|
remind you of this. Just @code{$} refers to the most recent value in
|
|
the history, and @code{$$} refers to the value before that.
|
|
@code{$$@var{n}} refers to the @var{n}th value from the end; @code{$$2}
|
|
is the value just prior to @code{$$}, @code{$$1} is equivalent to
|
|
@code{$$}, and @code{$$0} is equivalent to @code{$}.
|
|
|
|
For example, suppose you have just printed a pointer to a structure and
|
|
want to see the contents of the structure. It suffices to type
|
|
|
|
@smallexample
|
|
p *$
|
|
@end smallexample
|
|
|
|
If you have a chain of structures where the component @code{next} points
|
|
to the next one, you can print the contents of the next one with this:
|
|
|
|
@smallexample
|
|
p *$.next
|
|
@end smallexample
|
|
|
|
@noindent
|
|
You can print successive links in the chain by repeating this
|
|
command---which you can do by just typing @key{RET}.
|
|
|
|
Note that the history records values, not expressions. If the value of
|
|
@code{x} is 4 and you type these commands:
|
|
|
|
@smallexample
|
|
print x
|
|
set x=5
|
|
@end smallexample
|
|
|
|
@noindent
|
|
then the value recorded in the value history by the @code{print} command
|
|
remains 4 even though the value of @code{x} has changed.
|
|
|
|
@table @code
|
|
@kindex show values
|
|
@item show values
|
|
Print the last ten values in the value history, with their item numbers.
|
|
This is like @samp{p@ $$9} repeated ten times, except that @code{show
|
|
values} does not change the history.
|
|
|
|
@item show values @var{n}
|
|
Print ten history values centered on history item number @var{n}.
|
|
|
|
@item show values +
|
|
Print ten history values just after the values last printed. If no more
|
|
values are available, @code{show values +} produces no display.
|
|
@end table
|
|
|
|
Pressing @key{RET} to repeat @code{show values @var{n}} has exactly the
|
|
same effect as @samp{show values +}.
|
|
|
|
@node Convenience Vars
|
|
@section Convenience Variables
|
|
|
|
@cindex convenience variables
|
|
@cindex user-defined variables
|
|
@value{GDBN} provides @dfn{convenience variables} that you can use within
|
|
@value{GDBN} to hold on to a value and refer to it later. These variables
|
|
exist entirely within @value{GDBN}; they are not part of your program, and
|
|
setting a convenience variable has no direct effect on further execution
|
|
of your program. That is why you can use them freely.
|
|
|
|
Convenience variables are prefixed with @samp{$}. Any name preceded by
|
|
@samp{$} can be used for a convenience variable, unless it is one of
|
|
the predefined machine-specific register names (@pxref{Registers, ,Registers}).
|
|
(Value history references, in contrast, are @emph{numbers} preceded
|
|
by @samp{$}. @xref{Value History, ,Value History}.)
|
|
|
|
You can save a value in a convenience variable with an assignment
|
|
expression, just as you would set a variable in your program.
|
|
For example:
|
|
|
|
@smallexample
|
|
set $foo = *object_ptr
|
|
@end smallexample
|
|
|
|
@noindent
|
|
would save in @code{$foo} the value contained in the object pointed to by
|
|
@code{object_ptr}.
|
|
|
|
Using a convenience variable for the first time creates it, but its
|
|
value is @code{void} until you assign a new value. You can alter the
|
|
value with another assignment at any time.
|
|
|
|
Convenience variables have no fixed types. You can assign a convenience
|
|
variable any type of value, including structures and arrays, even if
|
|
that variable already has a value of a different type. The convenience
|
|
variable, when used as an expression, has the type of its current value.
|
|
|
|
@table @code
|
|
@kindex show convenience
|
|
@cindex show all user variables
|
|
@item show convenience
|
|
Print a list of convenience variables used so far, and their values.
|
|
Abbreviated @code{show conv}.
|
|
|
|
@kindex init-if-undefined
|
|
@cindex convenience variables, initializing
|
|
@item init-if-undefined $@var{variable} = @var{expression}
|
|
Set a convenience variable if it has not already been set. This is useful
|
|
for user-defined commands that keep some state. It is similar, in concept,
|
|
to using local static variables with initializers in C (except that
|
|
convenience variables are global). It can also be used to allow users to
|
|
override default values used in a command script.
|
|
|
|
If the variable is already defined then the expression is not evaluated so
|
|
any side-effects do not occur.
|
|
@end table
|
|
|
|
One of the ways to use a convenience variable is as a counter to be
|
|
incremented or a pointer to be advanced. For example, to print
|
|
a field from successive elements of an array of structures:
|
|
|
|
@smallexample
|
|
set $i = 0
|
|
print bar[$i++]->contents
|
|
@end smallexample
|
|
|
|
@noindent
|
|
Repeat that command by typing @key{RET}.
|
|
|
|
Some convenience variables are created automatically by @value{GDBN} and given
|
|
values likely to be useful.
|
|
|
|
@table @code
|
|
@vindex $_@r{, convenience variable}
|
|
@item $_
|
|
The variable @code{$_} is automatically set by the @code{x} command to
|
|
the last address examined (@pxref{Memory, ,Examining Memory}). Other
|
|
commands which provide a default address for @code{x} to examine also
|
|
set @code{$_} to that address; these commands include @code{info line}
|
|
and @code{info breakpoint}. The type of @code{$_} is @code{void *}
|
|
except when set by the @code{x} command, in which case it is a pointer
|
|
to the type of @code{$__}.
|
|
|
|
@vindex $__@r{, convenience variable}
|
|
@item $__
|
|
The variable @code{$__} is automatically set by the @code{x} command
|
|
to the value found in the last address examined. Its type is chosen
|
|
to match the format in which the data was printed.
|
|
|
|
@item $_exitcode
|
|
@vindex $_exitcode@r{, convenience variable}
|
|
The variable @code{$_exitcode} is automatically set to the exit code when
|
|
the program being debugged terminates.
|
|
|
|
@item $_probe_argc
|
|
@itemx $_probe_arg0@dots{}$_probe_arg11
|
|
Arguments to a static probe. @xref{Static Probe Points}.
|
|
|
|
@item $_sdata
|
|
@vindex $_sdata@r{, inspect, convenience variable}
|
|
The variable @code{$_sdata} contains extra collected static tracepoint
|
|
data. @xref{Tracepoint Actions,,Tracepoint Action Lists}. Note that
|
|
@code{$_sdata} could be empty, if not inspecting a trace buffer, or
|
|
if extra static tracepoint data has not been collected.
|
|
|
|
@item $_siginfo
|
|
@vindex $_siginfo@r{, convenience variable}
|
|
The variable @code{$_siginfo} contains extra signal information
|
|
(@pxref{extra signal information}). Note that @code{$_siginfo}
|
|
could be empty, if the application has not yet received any signals.
|
|
For example, it will be empty before you execute the @code{run} command.
|
|
|
|
@item $_tlb
|
|
@vindex $_tlb@r{, convenience variable}
|
|
The variable @code{$_tlb} is automatically set when debugging
|
|
applications running on MS-Windows in native mode or connected to
|
|
gdbserver that supports the @code{qGetTIBAddr} request.
|
|
@xref{General Query Packets}.
|
|
This variable contains the address of the thread information block.
|
|
|
|
@end table
|
|
|
|
On HP-UX systems, if you refer to a function or variable name that
|
|
begins with a dollar sign, @value{GDBN} searches for a user or system
|
|
name first, before it searches for a convenience variable.
|
|
|
|
@cindex convenience functions
|
|
@value{GDBN} also supplies some @dfn{convenience functions}. These
|
|
have a syntax similar to convenience variables. A convenience
|
|
function can be used in an expression just like an ordinary function;
|
|
however, a convenience function is implemented internally to
|
|
@value{GDBN}.
|
|
|
|
@table @code
|
|
@item help function
|
|
@kindex help function
|
|
@cindex show all convenience functions
|
|
Print a list of all convenience functions.
|
|
@end table
|
|
|
|
@node Registers
|
|
@section Registers
|
|
|
|
@cindex registers
|
|
You can refer to machine register contents, in expressions, as variables
|
|
with names starting with @samp{$}. The names of registers are different
|
|
for each machine; use @code{info registers} to see the names used on
|
|
your machine.
|
|
|
|
@table @code
|
|
@kindex info registers
|
|
@item info registers
|
|
Print the names and values of all registers except floating-point
|
|
and vector registers (in the selected stack frame).
|
|
|
|
@kindex info all-registers
|
|
@cindex floating point registers
|
|
@item info all-registers
|
|
Print the names and values of all registers, including floating-point
|
|
and vector registers (in the selected stack frame).
|
|
|
|
@item info registers @var{regname} @dots{}
|
|
Print the @dfn{relativized} value of each specified register @var{regname}.
|
|
As discussed in detail below, register values are normally relative to
|
|
the selected stack frame. @var{regname} may be any register name valid on
|
|
the machine you are using, with or without the initial @samp{$}.
|
|
@end table
|
|
|
|
@cindex stack pointer register
|
|
@cindex program counter register
|
|
@cindex process status register
|
|
@cindex frame pointer register
|
|
@cindex standard registers
|
|
@value{GDBN} has four ``standard'' register names that are available (in
|
|
expressions) on most machines---whenever they do not conflict with an
|
|
architecture's canonical mnemonics for registers. The register names
|
|
@code{$pc} and @code{$sp} are used for the program counter register and
|
|
the stack pointer. @code{$fp} is used for a register that contains a
|
|
pointer to the current stack frame, and @code{$ps} is used for a
|
|
register that contains the processor status. For example,
|
|
you could print the program counter in hex with
|
|
|
|
@smallexample
|
|
p/x $pc
|
|
@end smallexample
|
|
|
|
@noindent
|
|
or print the instruction to be executed next with
|
|
|
|
@smallexample
|
|
x/i $pc
|
|
@end smallexample
|
|
|
|
@noindent
|
|
or add four to the stack pointer@footnote{This is a way of removing
|
|
one word from the stack, on machines where stacks grow downward in
|
|
memory (most machines, nowadays). This assumes that the innermost
|
|
stack frame is selected; setting @code{$sp} is not allowed when other
|
|
stack frames are selected. To pop entire frames off the stack,
|
|
regardless of machine architecture, use @code{return};
|
|
see @ref{Returning, ,Returning from a Function}.} with
|
|
|
|
@smallexample
|
|
set $sp += 4
|
|
@end smallexample
|
|
|
|
Whenever possible, these four standard register names are available on
|
|
your machine even though the machine has different canonical mnemonics,
|
|
so long as there is no conflict. The @code{info registers} command
|
|
shows the canonical names. For example, on the SPARC, @code{info
|
|
registers} displays the processor status register as @code{$psr} but you
|
|
can also refer to it as @code{$ps}; and on x86-based machines @code{$ps}
|
|
is an alias for the @sc{eflags} register.
|
|
|
|
@value{GDBN} always considers the contents of an ordinary register as an
|
|
integer when the register is examined in this way. Some machines have
|
|
special registers which can hold nothing but floating point; these
|
|
registers are considered to have floating point values. There is no way
|
|
to refer to the contents of an ordinary register as floating point value
|
|
(although you can @emph{print} it as a floating point value with
|
|
@samp{print/f $@var{regname}}).
|
|
|
|
Some registers have distinct ``raw'' and ``virtual'' data formats. This
|
|
means that the data format in which the register contents are saved by
|
|
the operating system is not the same one that your program normally
|
|
sees. For example, the registers of the 68881 floating point
|
|
coprocessor are always saved in ``extended'' (raw) format, but all C
|
|
programs expect to work with ``double'' (virtual) format. In such
|
|
cases, @value{GDBN} normally works with the virtual format only (the format
|
|
that makes sense for your program), but the @code{info registers} command
|
|
prints the data in both formats.
|
|
|
|
@cindex SSE registers (x86)
|
|
@cindex MMX registers (x86)
|
|
Some machines have special registers whose contents can be interpreted
|
|
in several different ways. For example, modern x86-based machines
|
|
have SSE and MMX registers that can hold several values packed
|
|
together in several different formats. @value{GDBN} refers to such
|
|
registers in @code{struct} notation:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) print $xmm1
|
|
$1 = @{
|
|
v4_float = @{0, 3.43859137e-038, 1.54142831e-044, 1.821688e-044@},
|
|
v2_double = @{9.92129282474342e-303, 2.7585945287983262e-313@},
|
|
v16_int8 = "\000\000\000\000\3706;\001\v\000\000\000\r\000\000",
|
|
v8_int16 = @{0, 0, 14072, 315, 11, 0, 13, 0@},
|
|
v4_int32 = @{0, 20657912, 11, 13@},
|
|
v2_int64 = @{88725056443645952, 55834574859@},
|
|
uint128 = 0x0000000d0000000b013b36f800000000
|
|
@}
|
|
@end smallexample
|
|
|
|
@noindent
|
|
To set values of such registers, you need to tell @value{GDBN} which
|
|
view of the register you wish to change, as if you were assigning
|
|
value to a @code{struct} member:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) set $xmm1.uint128 = 0x000000000000000000000000FFFFFFFF
|
|
@end smallexample
|
|
|
|
Normally, register values are relative to the selected stack frame
|
|
(@pxref{Selection, ,Selecting a Frame}). This means that you get the
|
|
value that the register would contain if all stack frames farther in
|
|
were exited and their saved registers restored. In order to see the
|
|
true contents of hardware registers, you must select the innermost
|
|
frame (with @samp{frame 0}).
|
|
|
|
However, @value{GDBN} must deduce where registers are saved, from the machine
|
|
code generated by your compiler. If some registers are not saved, or if
|
|
@value{GDBN} is unable to locate the saved registers, the selected stack
|
|
frame makes no difference.
|
|
|
|
@node Floating Point Hardware
|
|
@section Floating Point Hardware
|
|
@cindex floating point
|
|
|
|
Depending on the configuration, @value{GDBN} may be able to give
|
|
you more information about the status of the floating point hardware.
|
|
|
|
@table @code
|
|
@kindex info float
|
|
@item info float
|
|
Display hardware-dependent information about the floating
|
|
point unit. The exact contents and layout vary depending on the
|
|
floating point chip. Currently, @samp{info float} is supported on
|
|
the ARM and x86 machines.
|
|
@end table
|
|
|
|
@node Vector Unit
|
|
@section Vector Unit
|
|
@cindex vector unit
|
|
|
|
Depending on the configuration, @value{GDBN} may be able to give you
|
|
more information about the status of the vector unit.
|
|
|
|
@table @code
|
|
@kindex info vector
|
|
@item info vector
|
|
Display information about the vector unit. The exact contents and
|
|
layout vary depending on the hardware.
|
|
@end table
|
|
|
|
@node OS Information
|
|
@section Operating System Auxiliary Information
|
|
@cindex OS information
|
|
|
|
@value{GDBN} provides interfaces to useful OS facilities that can help
|
|
you debug your program.
|
|
|
|
@cindex @code{ptrace} system call
|
|
@cindex @code{struct user} contents
|
|
When @value{GDBN} runs on a @dfn{Posix system} (such as GNU or Unix
|
|
machines), it interfaces with the inferior via the @code{ptrace}
|
|
system call. The operating system creates a special sata structure,
|
|
called @code{struct user}, for this interface. You can use the
|
|
command @code{info udot} to display the contents of this data
|
|
structure.
|
|
|
|
@table @code
|
|
@item info udot
|
|
@kindex info udot
|
|
Display the contents of the @code{struct user} maintained by the OS
|
|
kernel for the program being debugged. @value{GDBN} displays the
|
|
contents of @code{struct user} as a list of hex numbers, similar to
|
|
the @code{examine} command.
|
|
@end table
|
|
|
|
@cindex auxiliary vector
|
|
@cindex vector, auxiliary
|
|
Some operating systems supply an @dfn{auxiliary vector} to programs at
|
|
startup. This is akin to the arguments and environment that you
|
|
specify for a program, but contains a system-dependent variety of
|
|
binary values that tell system libraries important details about the
|
|
hardware, operating system, and process. Each value's purpose is
|
|
identified by an integer tag; the meanings are well-known but system-specific.
|
|
Depending on the configuration and operating system facilities,
|
|
@value{GDBN} may be able to show you this information. For remote
|
|
targets, this functionality may further depend on the remote stub's
|
|
support of the @samp{qXfer:auxv:read} packet, see
|
|
@ref{qXfer auxiliary vector read}.
|
|
|
|
@table @code
|
|
@kindex info auxv
|
|
@item info auxv
|
|
Display the auxiliary vector of the inferior, which can be either a
|
|
live process or a core dump file. @value{GDBN} prints each tag value
|
|
numerically, and also shows names and text descriptions for recognized
|
|
tags. Some values in the vector are numbers, some bit masks, and some
|
|
pointers to strings or other data. @value{GDBN} displays each value in the
|
|
most appropriate form for a recognized tag, and in hexadecimal for
|
|
an unrecognized tag.
|
|
@end table
|
|
|
|
On some targets, @value{GDBN} can access operating system-specific
|
|
information and show it to you. The types of information available
|
|
will differ depending on the type of operating system running on the
|
|
target. The mechanism used to fetch the data is described in
|
|
@ref{Operating System Information}. For remote targets, this
|
|
functionality depends on the remote stub's support of the
|
|
@samp{qXfer:osdata:read} packet, see @ref{qXfer osdata read}.
|
|
|
|
@table @code
|
|
@kindex info os
|
|
@item info os @var{infotype}
|
|
|
|
Display OS information of the requested type.
|
|
|
|
On @sc{gnu}/Linux, the following values of @var{infotype} are valid:
|
|
|
|
@anchor{linux info os infotypes}
|
|
@table @code
|
|
@kindex info os processes
|
|
@item processes
|
|
Display the list of processes on the target. For each process,
|
|
@value{GDBN} prints the process identifier, the name of the user, the
|
|
command corresponding to the process, and the list of processor cores
|
|
that the process is currently running on. (To understand what these
|
|
properties mean, for this and the following info types, please consult
|
|
the general @sc{gnu}/Linux documentation.)
|
|
|
|
@kindex info os procgroups
|
|
@item procgroups
|
|
Display the list of process groups on the target. For each process,
|
|
@value{GDBN} prints the identifier of the process group that it belongs
|
|
to, the command corresponding to the process group leader, the process
|
|
identifier, and the command line of the process. The list is sorted
|
|
first by the process group identifier, then by the process identifier,
|
|
so that processes belonging to the same process group are grouped together
|
|
and the process group leader is listed first.
|
|
|
|
@kindex info os threads
|
|
@item threads
|
|
Display the list of threads running on the target. For each thread,
|
|
@value{GDBN} prints the identifier of the process that the thread
|
|
belongs to, the command of the process, the thread identifier, and the
|
|
processor core that it is currently running on. The main thread of a
|
|
process is not listed.
|
|
|
|
@kindex info os files
|
|
@item files
|
|
Display the list of open file descriptors on the target. For each
|
|
file descriptor, @value{GDBN} prints the identifier of the process
|
|
owning the descriptor, the command of the owning process, the value
|
|
of the descriptor, and the target of the descriptor.
|
|
|
|
@kindex info os sockets
|
|
@item sockets
|
|
Display the list of Internet-domain sockets on the target. For each
|
|
socket, @value{GDBN} prints the address and port of the local and
|
|
remote endpoints, the current state of the connection, the creator of
|
|
the socket, the IP address family of the socket, and the type of the
|
|
connection.
|
|
|
|
@kindex info os shm
|
|
@item shm
|
|
Display the list of all System V shared-memory regions on the target.
|
|
For each shared-memory region, @value{GDBN} prints the region key,
|
|
the shared-memory identifier, the access permissions, the size of the
|
|
region, the process that created the region, the process that last
|
|
attached to or detached from the region, the current number of live
|
|
attaches to the region, and the times at which the region was last
|
|
attached to, detach from, and changed.
|
|
|
|
@kindex info os semaphores
|
|
@item semaphores
|
|
Display the list of all System V semaphore sets on the target. For each
|
|
semaphore set, @value{GDBN} prints the semaphore set key, the semaphore
|
|
set identifier, the access permissions, the number of semaphores in the
|
|
set, the user and group of the owner and creator of the semaphore set,
|
|
and the times at which the semaphore set was operated upon and changed.
|
|
|
|
@kindex info os msg
|
|
@item msg
|
|
Display the list of all System V message queues on the target. For each
|
|
message queue, @value{GDBN} prints the message queue key, the message
|
|
queue identifier, the access permissions, the current number of bytes
|
|
on the queue, the current number of messages on the queue, the processes
|
|
that last sent and received a message on the queue, the user and group
|
|
of the owner and creator of the message queue, the times at which a
|
|
message was last sent and received on the queue, and the time at which
|
|
the message queue was last changed.
|
|
|
|
@kindex info os modules
|
|
@item modules
|
|
Display the list of all loaded kernel modules on the target. For each
|
|
module, @value{GDBN} prints the module name, the size of the module in
|
|
bytes, the number of times the module is used, the dependencies of the
|
|
module, the status of the module, and the address of the loaded module
|
|
in memory.
|
|
@end table
|
|
|
|
@item info os
|
|
If @var{infotype} is omitted, then list the possible values for
|
|
@var{infotype} and the kind of OS information available for each
|
|
@var{infotype}. If the target does not return a list of possible
|
|
types, this command will report an error.
|
|
@end table
|
|
|
|
@node Memory Region Attributes
|
|
@section Memory Region Attributes
|
|
@cindex memory region attributes
|
|
|
|
@dfn{Memory region attributes} allow you to describe special handling
|
|
required by regions of your target's memory. @value{GDBN} uses
|
|
attributes to determine whether to allow certain types of memory
|
|
accesses; whether to use specific width accesses; and whether to cache
|
|
target memory. By default the description of memory regions is
|
|
fetched from the target (if the current target supports this), but the
|
|
user can override the fetched regions.
|
|
|
|
Defined memory regions can be individually enabled and disabled. When a
|
|
memory region is disabled, @value{GDBN} uses the default attributes when
|
|
accessing memory in that region. Similarly, if no memory regions have
|
|
been defined, @value{GDBN} uses the default attributes when accessing
|
|
all memory.
|
|
|
|
When a memory region is defined, it is given a number to identify it;
|
|
to enable, disable, or remove a memory region, you specify that number.
|
|
|
|
@table @code
|
|
@kindex mem
|
|
@item mem @var{lower} @var{upper} @var{attributes}@dots{}
|
|
Define a memory region bounded by @var{lower} and @var{upper} with
|
|
attributes @var{attributes}@dots{}, and add it to the list of regions
|
|
monitored by @value{GDBN}. Note that @var{upper} == 0 is a special
|
|
case: it is treated as the target's maximum memory address.
|
|
(0xffff on 16 bit targets, 0xffffffff on 32 bit targets, etc.)
|
|
|
|
@item mem auto
|
|
Discard any user changes to the memory regions and use target-supplied
|
|
regions, if available, or no regions if the target does not support.
|
|
|
|
@kindex delete mem
|
|
@item delete mem @var{nums}@dots{}
|
|
Remove memory regions @var{nums}@dots{} from the list of regions
|
|
monitored by @value{GDBN}.
|
|
|
|
@kindex disable mem
|
|
@item disable mem @var{nums}@dots{}
|
|
Disable monitoring of memory regions @var{nums}@dots{}.
|
|
A disabled memory region is not forgotten.
|
|
It may be enabled again later.
|
|
|
|
@kindex enable mem
|
|
@item enable mem @var{nums}@dots{}
|
|
Enable monitoring of memory regions @var{nums}@dots{}.
|
|
|
|
@kindex info mem
|
|
@item info mem
|
|
Print a table of all defined memory regions, with the following columns
|
|
for each region:
|
|
|
|
@table @emph
|
|
@item Memory Region Number
|
|
@item Enabled or Disabled.
|
|
Enabled memory regions are marked with @samp{y}.
|
|
Disabled memory regions are marked with @samp{n}.
|
|
|
|
@item Lo Address
|
|
The address defining the inclusive lower bound of the memory region.
|
|
|
|
@item Hi Address
|
|
The address defining the exclusive upper bound of the memory region.
|
|
|
|
@item Attributes
|
|
The list of attributes set for this memory region.
|
|
@end table
|
|
@end table
|
|
|
|
|
|
@subsection Attributes
|
|
|
|
@subsubsection Memory Access Mode
|
|
The access mode attributes set whether @value{GDBN} may make read or
|
|
write accesses to a memory region.
|
|
|
|
While these attributes prevent @value{GDBN} from performing invalid
|
|
memory accesses, they do nothing to prevent the target system, I/O DMA,
|
|
etc.@: from accessing memory.
|
|
|
|
@table @code
|
|
@item ro
|
|
Memory is read only.
|
|
@item wo
|
|
Memory is write only.
|
|
@item rw
|
|
Memory is read/write. This is the default.
|
|
@end table
|
|
|
|
@subsubsection Memory Access Size
|
|
The access size attribute tells @value{GDBN} to use specific sized
|
|
accesses in the memory region. Often memory mapped device registers
|
|
require specific sized accesses. If no access size attribute is
|
|
specified, @value{GDBN} may use accesses of any size.
|
|
|
|
@table @code
|
|
@item 8
|
|
Use 8 bit memory accesses.
|
|
@item 16
|
|
Use 16 bit memory accesses.
|
|
@item 32
|
|
Use 32 bit memory accesses.
|
|
@item 64
|
|
Use 64 bit memory accesses.
|
|
@end table
|
|
|
|
@c @subsubsection Hardware/Software Breakpoints
|
|
@c The hardware/software breakpoint attributes set whether @value{GDBN}
|
|
@c will use hardware or software breakpoints for the internal breakpoints
|
|
@c used by the step, next, finish, until, etc. commands.
|
|
@c
|
|
@c @table @code
|
|
@c @item hwbreak
|
|
@c Always use hardware breakpoints
|
|
@c @item swbreak (default)
|
|
@c @end table
|
|
|
|
@subsubsection Data Cache
|
|
The data cache attributes set whether @value{GDBN} will cache target
|
|
memory. While this generally improves performance by reducing debug
|
|
protocol overhead, it can lead to incorrect results because @value{GDBN}
|
|
does not know about volatile variables or memory mapped device
|
|
registers.
|
|
|
|
@table @code
|
|
@item cache
|
|
Enable @value{GDBN} to cache target memory.
|
|
@item nocache
|
|
Disable @value{GDBN} from caching target memory. This is the default.
|
|
@end table
|
|
|
|
@subsection Memory Access Checking
|
|
@value{GDBN} can be instructed to refuse accesses to memory that is
|
|
not explicitly described. This can be useful if accessing such
|
|
regions has undesired effects for a specific target, or to provide
|
|
better error checking. The following commands control this behaviour.
|
|
|
|
@table @code
|
|
@kindex set mem inaccessible-by-default
|
|
@item set mem inaccessible-by-default [on|off]
|
|
If @code{on} is specified, make @value{GDBN} treat memory not
|
|
explicitly described by the memory ranges as non-existent and refuse accesses
|
|
to such memory. The checks are only performed if there's at least one
|
|
memory range defined. If @code{off} is specified, make @value{GDBN}
|
|
treat the memory not explicitly described by the memory ranges as RAM.
|
|
The default value is @code{on}.
|
|
@kindex show mem inaccessible-by-default
|
|
@item show mem inaccessible-by-default
|
|
Show the current handling of accesses to unknown memory.
|
|
@end table
|
|
|
|
|
|
@c @subsubsection Memory Write Verification
|
|
@c The memory write verification attributes set whether @value{GDBN}
|
|
@c will re-reads data after each write to verify the write was successful.
|
|
@c
|
|
@c @table @code
|
|
@c @item verify
|
|
@c @item noverify (default)
|
|
@c @end table
|
|
|
|
@node Dump/Restore Files
|
|
@section Copy Between Memory and a File
|
|
@cindex dump/restore files
|
|
@cindex append data to a file
|
|
@cindex dump data to a file
|
|
@cindex restore data from a file
|
|
|
|
You can use the commands @code{dump}, @code{append}, and
|
|
@code{restore} to copy data between target memory and a file. The
|
|
@code{dump} and @code{append} commands write data to a file, and the
|
|
@code{restore} command reads data from a file back into the inferior's
|
|
memory. Files may be in binary, Motorola S-record, Intel hex, or
|
|
Tektronix Hex format; however, @value{GDBN} can only append to binary
|
|
files.
|
|
|
|
@table @code
|
|
|
|
@kindex dump
|
|
@item dump @r{[}@var{format}@r{]} memory @var{filename} @var{start_addr} @var{end_addr}
|
|
@itemx dump @r{[}@var{format}@r{]} value @var{filename} @var{expr}
|
|
Dump the contents of memory from @var{start_addr} to @var{end_addr},
|
|
or the value of @var{expr}, to @var{filename} in the given format.
|
|
|
|
The @var{format} parameter may be any one of:
|
|
@table @code
|
|
@item binary
|
|
Raw binary form.
|
|
@item ihex
|
|
Intel hex format.
|
|
@item srec
|
|
Motorola S-record format.
|
|
@item tekhex
|
|
Tektronix Hex format.
|
|
@end table
|
|
|
|
@value{GDBN} uses the same definitions of these formats as the
|
|
@sc{gnu} binary utilities, like @samp{objdump} and @samp{objcopy}. If
|
|
@var{format} is omitted, @value{GDBN} dumps the data in raw binary
|
|
form.
|
|
|
|
@kindex append
|
|
@item append @r{[}binary@r{]} memory @var{filename} @var{start_addr} @var{end_addr}
|
|
@itemx append @r{[}binary@r{]} value @var{filename} @var{expr}
|
|
Append the contents of memory from @var{start_addr} to @var{end_addr},
|
|
or the value of @var{expr}, to the file @var{filename}, in raw binary form.
|
|
(@value{GDBN} can only append data to files in raw binary form.)
|
|
|
|
@kindex restore
|
|
@item restore @var{filename} @r{[}binary@r{]} @var{bias} @var{start} @var{end}
|
|
Restore the contents of file @var{filename} into memory. The
|
|
@code{restore} command can automatically recognize any known @sc{bfd}
|
|
file format, except for raw binary. To restore a raw binary file you
|
|
must specify the optional keyword @code{binary} after the filename.
|
|
|
|
If @var{bias} is non-zero, its value will be added to the addresses
|
|
contained in the file. Binary files always start at address zero, so
|
|
they will be restored at address @var{bias}. Other bfd files have
|
|
a built-in location; they will be restored at offset @var{bias}
|
|
from that location.
|
|
|
|
If @var{start} and/or @var{end} are non-zero, then only data between
|
|
file offset @var{start} and file offset @var{end} will be restored.
|
|
These offsets are relative to the addresses in the file, before
|
|
the @var{bias} argument is applied.
|
|
|
|
@end table
|
|
|
|
@node Core File Generation
|
|
@section How to Produce a Core File from Your Program
|
|
@cindex dump core from inferior
|
|
|
|
A @dfn{core file} or @dfn{core dump} is a file that records the memory
|
|
image of a running process and its process status (register values
|
|
etc.). Its primary use is post-mortem debugging of a program that
|
|
crashed while it ran outside a debugger. A program that crashes
|
|
automatically produces a core file, unless this feature is disabled by
|
|
the user. @xref{Files}, for information on invoking @value{GDBN} in
|
|
the post-mortem debugging mode.
|
|
|
|
Occasionally, you may wish to produce a core file of the program you
|
|
are debugging in order to preserve a snapshot of its state.
|
|
@value{GDBN} has a special command for that.
|
|
|
|
@table @code
|
|
@kindex gcore
|
|
@kindex generate-core-file
|
|
@item generate-core-file [@var{file}]
|
|
@itemx gcore [@var{file}]
|
|
Produce a core dump of the inferior process. The optional argument
|
|
@var{file} specifies the file name where to put the core dump. If not
|
|
specified, the file name defaults to @file{core.@var{pid}}, where
|
|
@var{pid} is the inferior process ID.
|
|
|
|
Note that this command is implemented only for some systems (as of
|
|
this writing, @sc{gnu}/Linux, FreeBSD, Solaris, Unixware, and S390).
|
|
@end table
|
|
|
|
@node Character Sets
|
|
@section Character Sets
|
|
@cindex character sets
|
|
@cindex charset
|
|
@cindex translating between character sets
|
|
@cindex host character set
|
|
@cindex target character set
|
|
|
|
If the program you are debugging uses a different character set to
|
|
represent characters and strings than the one @value{GDBN} uses itself,
|
|
@value{GDBN} can automatically translate between the character sets for
|
|
you. The character set @value{GDBN} uses we call the @dfn{host
|
|
character set}; the one the inferior program uses we call the
|
|
@dfn{target character set}.
|
|
|
|
For example, if you are running @value{GDBN} on a @sc{gnu}/Linux system, which
|
|
uses the ISO Latin 1 character set, but you are using @value{GDBN}'s
|
|
remote protocol (@pxref{Remote Debugging}) to debug a program
|
|
running on an IBM mainframe, which uses the @sc{ebcdic} character set,
|
|
then the host character set is Latin-1, and the target character set is
|
|
@sc{ebcdic}. If you give @value{GDBN} the command @code{set
|
|
target-charset EBCDIC-US}, then @value{GDBN} translates between
|
|
@sc{ebcdic} and Latin 1 as you print character or string values, or use
|
|
character and string literals in expressions.
|
|
|
|
@value{GDBN} has no way to automatically recognize which character set
|
|
the inferior program uses; you must tell it, using the @code{set
|
|
target-charset} command, described below.
|
|
|
|
Here are the commands for controlling @value{GDBN}'s character set
|
|
support:
|
|
|
|
@table @code
|
|
@item set target-charset @var{charset}
|
|
@kindex set target-charset
|
|
Set the current target character set to @var{charset}. To display the
|
|
list of supported target character sets, type
|
|
@kbd{@w{set target-charset @key{TAB}@key{TAB}}}.
|
|
|
|
@item set host-charset @var{charset}
|
|
@kindex set host-charset
|
|
Set the current host character set to @var{charset}.
|
|
|
|
By default, @value{GDBN} uses a host character set appropriate to the
|
|
system it is running on; you can override that default using the
|
|
@code{set host-charset} command. On some systems, @value{GDBN} cannot
|
|
automatically determine the appropriate host character set. In this
|
|
case, @value{GDBN} uses @samp{UTF-8}.
|
|
|
|
@value{GDBN} can only use certain character sets as its host character
|
|
set. If you type @kbd{@w{set host-charset @key{TAB}@key{TAB}}},
|
|
@value{GDBN} will list the host character sets it supports.
|
|
|
|
@item set charset @var{charset}
|
|
@kindex set charset
|
|
Set the current host and target character sets to @var{charset}. As
|
|
above, if you type @kbd{@w{set charset @key{TAB}@key{TAB}}},
|
|
@value{GDBN} will list the names of the character sets that can be used
|
|
for both host and target.
|
|
|
|
@item show charset
|
|
@kindex show charset
|
|
Show the names of the current host and target character sets.
|
|
|
|
@item show host-charset
|
|
@kindex show host-charset
|
|
Show the name of the current host character set.
|
|
|
|
@item show target-charset
|
|
@kindex show target-charset
|
|
Show the name of the current target character set.
|
|
|
|
@item set target-wide-charset @var{charset}
|
|
@kindex set target-wide-charset
|
|
Set the current target's wide character set to @var{charset}. This is
|
|
the character set used by the target's @code{wchar_t} type. To
|
|
display the list of supported wide character sets, type
|
|
@kbd{@w{set target-wide-charset @key{TAB}@key{TAB}}}.
|
|
|
|
@item show target-wide-charset
|
|
@kindex show target-wide-charset
|
|
Show the name of the current target's wide character set.
|
|
@end table
|
|
|
|
Here is an example of @value{GDBN}'s character set support in action.
|
|
Assume that the following source code has been placed in the file
|
|
@file{charset-test.c}:
|
|
|
|
@smallexample
|
|
#include <stdio.h>
|
|
|
|
char ascii_hello[]
|
|
= @{72, 101, 108, 108, 111, 44, 32, 119,
|
|
111, 114, 108, 100, 33, 10, 0@};
|
|
char ibm1047_hello[]
|
|
= @{200, 133, 147, 147, 150, 107, 64, 166,
|
|
150, 153, 147, 132, 90, 37, 0@};
|
|
|
|
main ()
|
|
@{
|
|
printf ("Hello, world!\n");
|
|
@}
|
|
@end smallexample
|
|
|
|
In this program, @code{ascii_hello} and @code{ibm1047_hello} are arrays
|
|
containing the string @samp{Hello, world!} followed by a newline,
|
|
encoded in the @sc{ascii} and @sc{ibm1047} character sets.
|
|
|
|
We compile the program, and invoke the debugger on it:
|
|
|
|
@smallexample
|
|
$ gcc -g charset-test.c -o charset-test
|
|
$ gdb -nw charset-test
|
|
GNU gdb 2001-12-19-cvs
|
|
Copyright 2001 Free Software Foundation, Inc.
|
|
@dots{}
|
|
(@value{GDBP})
|
|
@end smallexample
|
|
|
|
We can use the @code{show charset} command to see what character sets
|
|
@value{GDBN} is currently using to interpret and display characters and
|
|
strings:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) show charset
|
|
The current host and target character set is `ISO-8859-1'.
|
|
(@value{GDBP})
|
|
@end smallexample
|
|
|
|
For the sake of printing this manual, let's use @sc{ascii} as our
|
|
initial character set:
|
|
@smallexample
|
|
(@value{GDBP}) set charset ASCII
|
|
(@value{GDBP}) show charset
|
|
The current host and target character set is `ASCII'.
|
|
(@value{GDBP})
|
|
@end smallexample
|
|
|
|
Let's assume that @sc{ascii} is indeed the correct character set for our
|
|
host system --- in other words, let's assume that if @value{GDBN} prints
|
|
characters using the @sc{ascii} character set, our terminal will display
|
|
them properly. Since our current target character set is also
|
|
@sc{ascii}, the contents of @code{ascii_hello} print legibly:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) print ascii_hello
|
|
$1 = 0x401698 "Hello, world!\n"
|
|
(@value{GDBP}) print ascii_hello[0]
|
|
$2 = 72 'H'
|
|
(@value{GDBP})
|
|
@end smallexample
|
|
|
|
@value{GDBN} uses the target character set for character and string
|
|
literals you use in expressions:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) print '+'
|
|
$3 = 43 '+'
|
|
(@value{GDBP})
|
|
@end smallexample
|
|
|
|
The @sc{ascii} character set uses the number 43 to encode the @samp{+}
|
|
character.
|
|
|
|
@value{GDBN} relies on the user to tell it which character set the
|
|
target program uses. If we print @code{ibm1047_hello} while our target
|
|
character set is still @sc{ascii}, we get jibberish:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) print ibm1047_hello
|
|
$4 = 0x4016a8 "\310\205\223\223\226k@@\246\226\231\223\204Z%"
|
|
(@value{GDBP}) print ibm1047_hello[0]
|
|
$5 = 200 '\310'
|
|
(@value{GDBP})
|
|
@end smallexample
|
|
|
|
If we invoke the @code{set target-charset} followed by @key{TAB}@key{TAB},
|
|
@value{GDBN} tells us the character sets it supports:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) set target-charset
|
|
ASCII EBCDIC-US IBM1047 ISO-8859-1
|
|
(@value{GDBP}) set target-charset
|
|
@end smallexample
|
|
|
|
We can select @sc{ibm1047} as our target character set, and examine the
|
|
program's strings again. Now the @sc{ascii} string is wrong, but
|
|
@value{GDBN} translates the contents of @code{ibm1047_hello} from the
|
|
target character set, @sc{ibm1047}, to the host character set,
|
|
@sc{ascii}, and they display correctly:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) set target-charset IBM1047
|
|
(@value{GDBP}) show charset
|
|
The current host character set is `ASCII'.
|
|
The current target character set is `IBM1047'.
|
|
(@value{GDBP}) print ascii_hello
|
|
$6 = 0x401698 "\110\145%%?\054\040\167?\162%\144\041\012"
|
|
(@value{GDBP}) print ascii_hello[0]
|
|
$7 = 72 '\110'
|
|
(@value{GDBP}) print ibm1047_hello
|
|
$8 = 0x4016a8 "Hello, world!\n"
|
|
(@value{GDBP}) print ibm1047_hello[0]
|
|
$9 = 200 'H'
|
|
(@value{GDBP})
|
|
@end smallexample
|
|
|
|
As above, @value{GDBN} uses the target character set for character and
|
|
string literals you use in expressions:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) print '+'
|
|
$10 = 78 '+'
|
|
(@value{GDBP})
|
|
@end smallexample
|
|
|
|
The @sc{ibm1047} character set uses the number 78 to encode the @samp{+}
|
|
character.
|
|
|
|
@node Caching Remote Data
|
|
@section Caching Data of Remote Targets
|
|
@cindex caching data of remote targets
|
|
|
|
@value{GDBN} caches data exchanged between the debugger and a
|
|
remote target (@pxref{Remote Debugging}). Such caching generally improves
|
|
performance, because it reduces the overhead of the remote protocol by
|
|
bundling memory reads and writes into large chunks. Unfortunately, simply
|
|
caching everything would lead to incorrect results, since @value{GDBN}
|
|
does not necessarily know anything about volatile values, memory-mapped I/O
|
|
addresses, etc. Furthermore, in non-stop mode (@pxref{Non-Stop Mode})
|
|
memory can be changed @emph{while} a gdb command is executing.
|
|
Therefore, by default, @value{GDBN} only caches data
|
|
known to be on the stack@footnote{In non-stop mode, it is moderately
|
|
rare for a running thread to modify the stack of a stopped thread
|
|
in a way that would interfere with a backtrace, and caching of
|
|
stack reads provides a significant speed up of remote backtraces.}.
|
|
Other regions of memory can be explicitly marked as
|
|
cacheable; see @pxref{Memory Region Attributes}.
|
|
|
|
@table @code
|
|
@kindex set remotecache
|
|
@item set remotecache on
|
|
@itemx set remotecache off
|
|
This option no longer does anything; it exists for compatibility
|
|
with old scripts.
|
|
|
|
@kindex show remotecache
|
|
@item show remotecache
|
|
Show the current state of the obsolete remotecache flag.
|
|
|
|
@kindex set stack-cache
|
|
@item set stack-cache on
|
|
@itemx set stack-cache off
|
|
Enable or disable caching of stack accesses. When @code{ON}, use
|
|
caching. By default, this option is @code{ON}.
|
|
|
|
@kindex show stack-cache
|
|
@item show stack-cache
|
|
Show the current state of data caching for memory accesses.
|
|
|
|
@kindex info dcache
|
|
@item info dcache @r{[}line@r{]}
|
|
Print the information about the data cache performance. The
|
|
information displayed includes the dcache width and depth, and for
|
|
each cache line, its number, address, and how many times it was
|
|
referenced. This command is useful for debugging the data cache
|
|
operation.
|
|
|
|
If a line number is specified, the contents of that line will be
|
|
printed in hex.
|
|
|
|
@item set dcache size @var{size}
|
|
@cindex dcache size
|
|
@kindex set dcache size
|
|
Set maximum number of entries in dcache (dcache depth above).
|
|
|
|
@item set dcache line-size @var{line-size}
|
|
@cindex dcache line-size
|
|
@kindex set dcache line-size
|
|
Set number of bytes each dcache entry caches (dcache width above).
|
|
Must be a power of 2.
|
|
|
|
@item show dcache size
|
|
@kindex show dcache size
|
|
Show maximum number of dcache entries. See also @ref{Caching Remote Data, info dcache}.
|
|
|
|
@item show dcache line-size
|
|
@kindex show dcache line-size
|
|
Show default size of dcache lines. See also @ref{Caching Remote Data, info dcache}.
|
|
|
|
@end table
|
|
|
|
@node Searching Memory
|
|
@section Search Memory
|
|
@cindex searching memory
|
|
|
|
Memory can be searched for a particular sequence of bytes with the
|
|
@code{find} command.
|
|
|
|
@table @code
|
|
@kindex find
|
|
@item find @r{[}/@var{sn}@r{]} @var{start_addr}, +@var{len}, @var{val1} @r{[}, @var{val2}, @dots{}@r{]}
|
|
@itemx find @r{[}/@var{sn}@r{]} @var{start_addr}, @var{end_addr}, @var{val1} @r{[}, @var{val2}, @dots{}@r{]}
|
|
Search memory for the sequence of bytes specified by @var{val1}, @var{val2},
|
|
etc. The search begins at address @var{start_addr} and continues for either
|
|
@var{len} bytes or through to @var{end_addr} inclusive.
|
|
@end table
|
|
|
|
@var{s} and @var{n} are optional parameters.
|
|
They may be specified in either order, apart or together.
|
|
|
|
@table @r
|
|
@item @var{s}, search query size
|
|
The size of each search query value.
|
|
|
|
@table @code
|
|
@item b
|
|
bytes
|
|
@item h
|
|
halfwords (two bytes)
|
|
@item w
|
|
words (four bytes)
|
|
@item g
|
|
giant words (eight bytes)
|
|
@end table
|
|
|
|
All values are interpreted in the current language.
|
|
This means, for example, that if the current source language is C/C@t{++}
|
|
then searching for the string ``hello'' includes the trailing '\0'.
|
|
|
|
If the value size is not specified, it is taken from the
|
|
value's type in the current language.
|
|
This is useful when one wants to specify the search
|
|
pattern as a mixture of types.
|
|
Note that this means, for example, that in the case of C-like languages
|
|
a search for an untyped 0x42 will search for @samp{(int) 0x42}
|
|
which is typically four bytes.
|
|
|
|
@item @var{n}, maximum number of finds
|
|
The maximum number of matches to print. The default is to print all finds.
|
|
@end table
|
|
|
|
You can use strings as search values. Quote them with double-quotes
|
|
(@code{"}).
|
|
The string value is copied into the search pattern byte by byte,
|
|
regardless of the endianness of the target and the size specification.
|
|
|
|
The address of each match found is printed as well as a count of the
|
|
number of matches found.
|
|
|
|
The address of the last value found is stored in convenience variable
|
|
@samp{$_}.
|
|
A count of the number of matches is stored in @samp{$numfound}.
|
|
|
|
For example, if stopped at the @code{printf} in this function:
|
|
|
|
@smallexample
|
|
void
|
|
hello ()
|
|
@{
|
|
static char hello[] = "hello-hello";
|
|
static struct @{ char c; short s; int i; @}
|
|
__attribute__ ((packed)) mixed
|
|
= @{ 'c', 0x1234, 0x87654321 @};
|
|
printf ("%s\n", hello);
|
|
@}
|
|
@end smallexample
|
|
|
|
@noindent
|
|
you get during debugging:
|
|
|
|
@smallexample
|
|
(gdb) find &hello[0], +sizeof(hello), "hello"
|
|
0x804956d <hello.1620+6>
|
|
1 pattern found
|
|
(gdb) find &hello[0], +sizeof(hello), 'h', 'e', 'l', 'l', 'o'
|
|
0x8049567 <hello.1620>
|
|
0x804956d <hello.1620+6>
|
|
2 patterns found
|
|
(gdb) find /b1 &hello[0], +sizeof(hello), 'h', 0x65, 'l'
|
|
0x8049567 <hello.1620>
|
|
1 pattern found
|
|
(gdb) find &mixed, +sizeof(mixed), (char) 'c', (short) 0x1234, (int) 0x87654321
|
|
0x8049560 <mixed.1625>
|
|
1 pattern found
|
|
(gdb) print $numfound
|
|
$1 = 1
|
|
(gdb) print $_
|
|
$2 = (void *) 0x8049560
|
|
@end smallexample
|
|
|
|
@node Optimized Code
|
|
@chapter Debugging Optimized Code
|
|
@cindex optimized code, debugging
|
|
@cindex debugging optimized code
|
|
|
|
Almost all compilers support optimization. With optimization
|
|
disabled, the compiler generates assembly code that corresponds
|
|
directly to your source code, in a simplistic way. As the compiler
|
|
applies more powerful optimizations, the generated assembly code
|
|
diverges from your original source code. With help from debugging
|
|
information generated by the compiler, @value{GDBN} can map from
|
|
the running program back to constructs from your original source.
|
|
|
|
@value{GDBN} is more accurate with optimization disabled. If you
|
|
can recompile without optimization, it is easier to follow the
|
|
progress of your program during debugging. But, there are many cases
|
|
where you may need to debug an optimized version.
|
|
|
|
When you debug a program compiled with @samp{-g -O}, remember that the
|
|
optimizer has rearranged your code; the debugger shows you what is
|
|
really there. Do not be too surprised when the execution path does not
|
|
exactly match your source file! An extreme example: if you define a
|
|
variable, but never use it, @value{GDBN} never sees that
|
|
variable---because the compiler optimizes it out of existence.
|
|
|
|
Some things do not work as well with @samp{-g -O} as with just
|
|
@samp{-g}, particularly on machines with instruction scheduling. If in
|
|
doubt, recompile with @samp{-g} alone, and if this fixes the problem,
|
|
please report it to us as a bug (including a test case!).
|
|
@xref{Variables}, for more information about debugging optimized code.
|
|
|
|
@menu
|
|
* Inline Functions:: How @value{GDBN} presents inlining
|
|
* Tail Call Frames:: @value{GDBN} analysis of jumps to functions
|
|
@end menu
|
|
|
|
@node Inline Functions
|
|
@section Inline Functions
|
|
@cindex inline functions, debugging
|
|
|
|
@dfn{Inlining} is an optimization that inserts a copy of the function
|
|
body directly at each call site, instead of jumping to a shared
|
|
routine. @value{GDBN} displays inlined functions just like
|
|
non-inlined functions. They appear in backtraces. You can view their
|
|
arguments and local variables, step into them with @code{step}, skip
|
|
them with @code{next}, and escape from them with @code{finish}.
|
|
You can check whether a function was inlined by using the
|
|
@code{info frame} command.
|
|
|
|
For @value{GDBN} to support inlined functions, the compiler must
|
|
record information about inlining in the debug information ---
|
|
@value{NGCC} using the @sc{dwarf 2} format does this, and several
|
|
other compilers do also. @value{GDBN} only supports inlined functions
|
|
when using @sc{dwarf 2}. Versions of @value{NGCC} before 4.1
|
|
do not emit two required attributes (@samp{DW_AT_call_file} and
|
|
@samp{DW_AT_call_line}); @value{GDBN} does not display inlined
|
|
function calls with earlier versions of @value{NGCC}. It instead
|
|
displays the arguments and local variables of inlined functions as
|
|
local variables in the caller.
|
|
|
|
The body of an inlined function is directly included at its call site;
|
|
unlike a non-inlined function, there are no instructions devoted to
|
|
the call. @value{GDBN} still pretends that the call site and the
|
|
start of the inlined function are different instructions. Stepping to
|
|
the call site shows the call site, and then stepping again shows
|
|
the first line of the inlined function, even though no additional
|
|
instructions are executed.
|
|
|
|
This makes source-level debugging much clearer; you can see both the
|
|
context of the call and then the effect of the call. Only stepping by
|
|
a single instruction using @code{stepi} or @code{nexti} does not do
|
|
this; single instruction steps always show the inlined body.
|
|
|
|
There are some ways that @value{GDBN} does not pretend that inlined
|
|
function calls are the same as normal calls:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
Setting breakpoints at the call site of an inlined function may not
|
|
work, because the call site does not contain any code. @value{GDBN}
|
|
may incorrectly move the breakpoint to the next line of the enclosing
|
|
function, after the call. This limitation will be removed in a future
|
|
version of @value{GDBN}; until then, set a breakpoint on an earlier line
|
|
or inside the inlined function instead.
|
|
|
|
@item
|
|
@value{GDBN} cannot locate the return value of inlined calls after
|
|
using the @code{finish} command. This is a limitation of compiler-generated
|
|
debugging information; after @code{finish}, you can step to the next line
|
|
and print a variable where your program stored the return value.
|
|
|
|
@end itemize
|
|
|
|
@node Tail Call Frames
|
|
@section Tail Call Frames
|
|
@cindex tail call frames, debugging
|
|
|
|
Function @code{B} can call function @code{C} in its very last statement. In
|
|
unoptimized compilation the call of @code{C} is immediately followed by return
|
|
instruction at the end of @code{B} code. Optimizing compiler may replace the
|
|
call and return in function @code{B} into one jump to function @code{C}
|
|
instead. Such use of a jump instruction is called @dfn{tail call}.
|
|
|
|
During execution of function @code{C}, there will be no indication in the
|
|
function call stack frames that it was tail-called from @code{B}. If function
|
|
@code{A} regularly calls function @code{B} which tail-calls function @code{C},
|
|
then @value{GDBN} will see @code{A} as the caller of @code{C}. However, in
|
|
some cases @value{GDBN} can determine that @code{C} was tail-called from
|
|
@code{B}, and it will then create fictitious call frame for that, with the
|
|
return address set up as if @code{B} called @code{C} normally.
|
|
|
|
This functionality is currently supported only by DWARF 2 debugging format and
|
|
the compiler has to produce @samp{DW_TAG_GNU_call_site} tags. With
|
|
@value{NGCC}, you need to specify @option{-O -g} during compilation, to get
|
|
this information.
|
|
|
|
@kbd{info frame} command (@pxref{Frame Info}) will indicate the tail call frame
|
|
kind by text @code{tail call frame} such as in this sample @value{GDBN} output:
|
|
|
|
@smallexample
|
|
(gdb) x/i $pc - 2
|
|
0x40066b <b(int, double)+11>: jmp 0x400640 <c(int, double)>
|
|
(gdb) info frame
|
|
Stack level 1, frame at 0x7fffffffda30:
|
|
rip = 0x40066d in b (amd64-entry-value.cc:59); saved rip 0x4004c5
|
|
tail call frame, caller of frame at 0x7fffffffda30
|
|
source language c++.
|
|
Arglist at unknown address.
|
|
Locals at unknown address, Previous frame's sp is 0x7fffffffda30
|
|
@end smallexample
|
|
|
|
The detection of all the possible code path executions can find them ambiguous.
|
|
There is no execution history stored (possible @ref{Reverse Execution} is never
|
|
used for this purpose) and the last known caller could have reached the known
|
|
callee by multiple different jump sequences. In such case @value{GDBN} still
|
|
tries to show at least all the unambiguous top tail callers and all the
|
|
unambiguous bottom tail calees, if any.
|
|
|
|
@table @code
|
|
@anchor{set debug entry-values}
|
|
@item set debug entry-values
|
|
@kindex set debug entry-values
|
|
When set to on, enables printing of analysis messages for both frame argument
|
|
values at function entry and tail calls. It will show all the possible valid
|
|
tail calls code paths it has considered. It will also print the intersection
|
|
of them with the final unambiguous (possibly partial or even empty) code path
|
|
result.
|
|
|
|
@item show debug entry-values
|
|
@kindex show debug entry-values
|
|
Show the current state of analysis messages printing for both frame argument
|
|
values at function entry and tail calls.
|
|
@end table
|
|
|
|
The analysis messages for tail calls can for example show why the virtual tail
|
|
call frame for function @code{c} has not been recognized (due to the indirect
|
|
reference by variable @code{x}):
|
|
|
|
@smallexample
|
|
static void __attribute__((noinline, noclone)) c (void);
|
|
void (*x) (void) = c;
|
|
static void __attribute__((noinline, noclone)) a (void) @{ x++; @}
|
|
static void __attribute__((noinline, noclone)) c (void) @{ a (); @}
|
|
int main (void) @{ x (); return 0; @}
|
|
|
|
Breakpoint 1, DW_OP_GNU_entry_value resolving cannot find
|
|
DW_TAG_GNU_call_site 0x40039a in main
|
|
a () at t.c:3
|
|
3 static void __attribute__((noinline, noclone)) a (void) @{ x++; @}
|
|
(gdb) bt
|
|
#0 a () at t.c:3
|
|
#1 0x000000000040039a in main () at t.c:5
|
|
@end smallexample
|
|
|
|
Another possibility is an ambiguous virtual tail call frames resolution:
|
|
|
|
@smallexample
|
|
int i;
|
|
static void __attribute__((noinline, noclone)) f (void) @{ i++; @}
|
|
static void __attribute__((noinline, noclone)) e (void) @{ f (); @}
|
|
static void __attribute__((noinline, noclone)) d (void) @{ f (); @}
|
|
static void __attribute__((noinline, noclone)) c (void) @{ d (); @}
|
|
static void __attribute__((noinline, noclone)) b (void)
|
|
@{ if (i) c (); else e (); @}
|
|
static void __attribute__((noinline, noclone)) a (void) @{ b (); @}
|
|
int main (void) @{ a (); return 0; @}
|
|
|
|
tailcall: initial: 0x4004d2(a) 0x4004ce(b) 0x4004b2(c) 0x4004a2(d)
|
|
tailcall: compare: 0x4004d2(a) 0x4004cc(b) 0x400492(e)
|
|
tailcall: reduced: 0x4004d2(a) |
|
|
(gdb) bt
|
|
#0 f () at t.c:2
|
|
#1 0x00000000004004d2 in a () at t.c:8
|
|
#2 0x0000000000400395 in main () at t.c:9
|
|
@end smallexample
|
|
|
|
@set CALLSEQ1A @code{main@value{ARROW}a@value{ARROW}b@value{ARROW}c@value{ARROW}d@value{ARROW}f}
|
|
@set CALLSEQ2A @code{main@value{ARROW}a@value{ARROW}b@value{ARROW}e@value{ARROW}f}
|
|
|
|
@c Convert CALLSEQ#A to CALLSEQ#B depending on HAVE_MAKEINFO_CLICK.
|
|
@ifset HAVE_MAKEINFO_CLICK
|
|
@set ARROW @click{}
|
|
@set CALLSEQ1B @clicksequence{@value{CALLSEQ1A}}
|
|
@set CALLSEQ2B @clicksequence{@value{CALLSEQ2A}}
|
|
@end ifset
|
|
@ifclear HAVE_MAKEINFO_CLICK
|
|
@set ARROW ->
|
|
@set CALLSEQ1B @value{CALLSEQ1A}
|
|
@set CALLSEQ2B @value{CALLSEQ2A}
|
|
@end ifclear
|
|
|
|
Frames #0 and #2 are real, #1 is a virtual tail call frame.
|
|
The code can have possible execution paths @value{CALLSEQ1B} or
|
|
@value{CALLSEQ2B}, @value{GDBN} cannot find which one from the inferior state.
|
|
|
|
@code{initial:} state shows some random possible calling sequence @value{GDBN}
|
|
has found. It then finds another possible calling sequcen - that one is
|
|
prefixed by @code{compare:}. The non-ambiguous intersection of these two is
|
|
printed as the @code{reduced:} calling sequence. That one could have many
|
|
futher @code{compare:} and @code{reduced:} statements as long as there remain
|
|
any non-ambiguous sequence entries.
|
|
|
|
For the frame of function @code{b} in both cases there are different possible
|
|
@code{$pc} values (@code{0x4004cc} or @code{0x4004ce}), therefore this frame is
|
|
also ambigous. The only non-ambiguous frame is the one for function @code{a},
|
|
therefore this one is displayed to the user while the ambiguous frames are
|
|
omitted.
|
|
|
|
There can be also reasons why printing of frame argument values at function
|
|
entry may fail:
|
|
|
|
@smallexample
|
|
int v;
|
|
static void __attribute__((noinline, noclone)) c (int i) @{ v++; @}
|
|
static void __attribute__((noinline, noclone)) a (int i);
|
|
static void __attribute__((noinline, noclone)) b (int i) @{ a (i); @}
|
|
static void __attribute__((noinline, noclone)) a (int i)
|
|
@{ if (i) b (i - 1); else c (0); @}
|
|
int main (void) @{ a (5); return 0; @}
|
|
|
|
(gdb) bt
|
|
#0 c (i=i@@entry=0) at t.c:2
|
|
#1 0x0000000000400428 in a (DW_OP_GNU_entry_value resolving has found
|
|
function "a" at 0x400420 can call itself via tail calls
|
|
i=<optimized out>) at t.c:6
|
|
#2 0x000000000040036e in main () at t.c:7
|
|
@end smallexample
|
|
|
|
@value{GDBN} cannot find out from the inferior state if and how many times did
|
|
function @code{a} call itself (via function @code{b}) as these calls would be
|
|
tail calls. Such tail calls would modify thue @code{i} variable, therefore
|
|
@value{GDBN} cannot be sure the value it knows would be right - @value{GDBN}
|
|
prints @code{<optimized out>} instead.
|
|
|
|
@node Macros
|
|
@chapter C Preprocessor Macros
|
|
|
|
Some languages, such as C and C@t{++}, provide a way to define and invoke
|
|
``preprocessor macros'' which expand into strings of tokens.
|
|
@value{GDBN} can evaluate expressions containing macro invocations, show
|
|
the result of macro expansion, and show a macro's definition, including
|
|
where it was defined.
|
|
|
|
You may need to compile your program specially to provide @value{GDBN}
|
|
with information about preprocessor macros. Most compilers do not
|
|
include macros in their debugging information, even when you compile
|
|
with the @option{-g} flag. @xref{Compilation}.
|
|
|
|
A program may define a macro at one point, remove that definition later,
|
|
and then provide a different definition after that. Thus, at different
|
|
points in the program, a macro may have different definitions, or have
|
|
no definition at all. If there is a current stack frame, @value{GDBN}
|
|
uses the macros in scope at that frame's source code line. Otherwise,
|
|
@value{GDBN} uses the macros in scope at the current listing location;
|
|
see @ref{List}.
|
|
|
|
Whenever @value{GDBN} evaluates an expression, it always expands any
|
|
macro invocations present in the expression. @value{GDBN} also provides
|
|
the following commands for working with macros explicitly.
|
|
|
|
@table @code
|
|
|
|
@kindex macro expand
|
|
@cindex macro expansion, showing the results of preprocessor
|
|
@cindex preprocessor macro expansion, showing the results of
|
|
@cindex expanding preprocessor macros
|
|
@item macro expand @var{expression}
|
|
@itemx macro exp @var{expression}
|
|
Show the results of expanding all preprocessor macro invocations in
|
|
@var{expression}. Since @value{GDBN} simply expands macros, but does
|
|
not parse the result, @var{expression} need not be a valid expression;
|
|
it can be any string of tokens.
|
|
|
|
@kindex macro exp1
|
|
@item macro expand-once @var{expression}
|
|
@itemx macro exp1 @var{expression}
|
|
@cindex expand macro once
|
|
@i{(This command is not yet implemented.)} Show the results of
|
|
expanding those preprocessor macro invocations that appear explicitly in
|
|
@var{expression}. Macro invocations appearing in that expansion are
|
|
left unchanged. This command allows you to see the effect of a
|
|
particular macro more clearly, without being confused by further
|
|
expansions. Since @value{GDBN} simply expands macros, but does not
|
|
parse the result, @var{expression} need not be a valid expression; it
|
|
can be any string of tokens.
|
|
|
|
@kindex info macro
|
|
@cindex macro definition, showing
|
|
@cindex definition of a macro, showing
|
|
@cindex macros, from debug info
|
|
@item info macro [-a|-all] [--] @var{macro}
|
|
Show the current definition or all definitions of the named @var{macro},
|
|
and describe the source location or compiler command-line where that
|
|
definition was established. The optional double dash is to signify the end of
|
|
argument processing and the beginning of @var{macro} for non C-like macros where
|
|
the macro may begin with a hyphen.
|
|
|
|
@kindex info macros
|
|
@item info macros @var{linespec}
|
|
Show all macro definitions that are in effect at the location specified
|
|
by @var{linespec}, and describe the source location or compiler
|
|
command-line where those definitions were established.
|
|
|
|
@kindex macro define
|
|
@cindex user-defined macros
|
|
@cindex defining macros interactively
|
|
@cindex macros, user-defined
|
|
@item macro define @var{macro} @var{replacement-list}
|
|
@itemx macro define @var{macro}(@var{arglist}) @var{replacement-list}
|
|
Introduce a definition for a preprocessor macro named @var{macro},
|
|
invocations of which are replaced by the tokens given in
|
|
@var{replacement-list}. The first form of this command defines an
|
|
``object-like'' macro, which takes no arguments; the second form
|
|
defines a ``function-like'' macro, which takes the arguments given in
|
|
@var{arglist}.
|
|
|
|
A definition introduced by this command is in scope in every
|
|
expression evaluated in @value{GDBN}, until it is removed with the
|
|
@code{macro undef} command, described below. The definition overrides
|
|
all definitions for @var{macro} present in the program being debugged,
|
|
as well as any previous user-supplied definition.
|
|
|
|
@kindex macro undef
|
|
@item macro undef @var{macro}
|
|
Remove any user-supplied definition for the macro named @var{macro}.
|
|
This command only affects definitions provided with the @code{macro
|
|
define} command, described above; it cannot remove definitions present
|
|
in the program being debugged.
|
|
|
|
@kindex macro list
|
|
@item macro list
|
|
List all the macros defined using the @code{macro define} command.
|
|
@end table
|
|
|
|
@cindex macros, example of debugging with
|
|
Here is a transcript showing the above commands in action. First, we
|
|
show our source files:
|
|
|
|
@smallexample
|
|
$ cat sample.c
|
|
#include <stdio.h>
|
|
#include "sample.h"
|
|
|
|
#define M 42
|
|
#define ADD(x) (M + x)
|
|
|
|
main ()
|
|
@{
|
|
#define N 28
|
|
printf ("Hello, world!\n");
|
|
#undef N
|
|
printf ("We're so creative.\n");
|
|
#define N 1729
|
|
printf ("Goodbye, world!\n");
|
|
@}
|
|
$ cat sample.h
|
|
#define Q <
|
|
$
|
|
@end smallexample
|
|
|
|
Now, we compile the program using the @sc{gnu} C compiler,
|
|
@value{NGCC}. We pass the @option{-gdwarf-2}@footnote{This is the
|
|
minimum. Recent versions of @value{NGCC} support @option{-gdwarf-3}
|
|
and @option{-gdwarf-4}; we recommend always choosing the most recent
|
|
version of DWARF.} @emph{and} @option{-g3} flags to ensure the compiler
|
|
includes information about preprocessor macros in the debugging
|
|
information.
|
|
|
|
@smallexample
|
|
$ gcc -gdwarf-2 -g3 sample.c -o sample
|
|
$
|
|
@end smallexample
|
|
|
|
Now, we start @value{GDBN} on our sample program:
|
|
|
|
@smallexample
|
|
$ gdb -nw sample
|
|
GNU gdb 2002-05-06-cvs
|
|
Copyright 2002 Free Software Foundation, Inc.
|
|
GDB is free software, @dots{}
|
|
(@value{GDBP})
|
|
@end smallexample
|
|
|
|
We can expand macros and examine their definitions, even when the
|
|
program is not running. @value{GDBN} uses the current listing position
|
|
to decide which macro definitions are in scope:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) list main
|
|
3
|
|
4 #define M 42
|
|
5 #define ADD(x) (M + x)
|
|
6
|
|
7 main ()
|
|
8 @{
|
|
9 #define N 28
|
|
10 printf ("Hello, world!\n");
|
|
11 #undef N
|
|
12 printf ("We're so creative.\n");
|
|
(@value{GDBP}) info macro ADD
|
|
Defined at /home/jimb/gdb/macros/play/sample.c:5
|
|
#define ADD(x) (M + x)
|
|
(@value{GDBP}) info macro Q
|
|
Defined at /home/jimb/gdb/macros/play/sample.h:1
|
|
included at /home/jimb/gdb/macros/play/sample.c:2
|
|
#define Q <
|
|
(@value{GDBP}) macro expand ADD(1)
|
|
expands to: (42 + 1)
|
|
(@value{GDBP}) macro expand-once ADD(1)
|
|
expands to: once (M + 1)
|
|
(@value{GDBP})
|
|
@end smallexample
|
|
|
|
In the example above, note that @code{macro expand-once} expands only
|
|
the macro invocation explicit in the original text --- the invocation of
|
|
@code{ADD} --- but does not expand the invocation of the macro @code{M},
|
|
which was introduced by @code{ADD}.
|
|
|
|
Once the program is running, @value{GDBN} uses the macro definitions in
|
|
force at the source line of the current stack frame:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) break main
|
|
Breakpoint 1 at 0x8048370: file sample.c, line 10.
|
|
(@value{GDBP}) run
|
|
Starting program: /home/jimb/gdb/macros/play/sample
|
|
|
|
Breakpoint 1, main () at sample.c:10
|
|
10 printf ("Hello, world!\n");
|
|
(@value{GDBP})
|
|
@end smallexample
|
|
|
|
At line 10, the definition of the macro @code{N} at line 9 is in force:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) info macro N
|
|
Defined at /home/jimb/gdb/macros/play/sample.c:9
|
|
#define N 28
|
|
(@value{GDBP}) macro expand N Q M
|
|
expands to: 28 < 42
|
|
(@value{GDBP}) print N Q M
|
|
$1 = 1
|
|
(@value{GDBP})
|
|
@end smallexample
|
|
|
|
As we step over directives that remove @code{N}'s definition, and then
|
|
give it a new definition, @value{GDBN} finds the definition (or lack
|
|
thereof) in force at each point:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) next
|
|
Hello, world!
|
|
12 printf ("We're so creative.\n");
|
|
(@value{GDBP}) info macro N
|
|
The symbol `N' has no definition as a C/C++ preprocessor macro
|
|
at /home/jimb/gdb/macros/play/sample.c:12
|
|
(@value{GDBP}) next
|
|
We're so creative.
|
|
14 printf ("Goodbye, world!\n");
|
|
(@value{GDBP}) info macro N
|
|
Defined at /home/jimb/gdb/macros/play/sample.c:13
|
|
#define N 1729
|
|
(@value{GDBP}) macro expand N Q M
|
|
expands to: 1729 < 42
|
|
(@value{GDBP}) print N Q M
|
|
$2 = 0
|
|
(@value{GDBP})
|
|
@end smallexample
|
|
|
|
In addition to source files, macros can be defined on the compilation command
|
|
line using the @option{-D@var{name}=@var{value}} syntax. For macros defined in
|
|
such a way, @value{GDBN} displays the location of their definition as line zero
|
|
of the source file submitted to the compiler.
|
|
|
|
@smallexample
|
|
(@value{GDBP}) info macro __STDC__
|
|
Defined at /home/jimb/gdb/macros/play/sample.c:0
|
|
-D__STDC__=1
|
|
(@value{GDBP})
|
|
@end smallexample
|
|
|
|
|
|
@node Tracepoints
|
|
@chapter Tracepoints
|
|
@c This chapter is based on the documentation written by Michael
|
|
@c Snyder, David Taylor, Jim Blandy, and Elena Zannoni.
|
|
|
|
@cindex tracepoints
|
|
In some applications, it is not feasible for the debugger to interrupt
|
|
the program's execution long enough for the developer to learn
|
|
anything helpful about its behavior. If the program's correctness
|
|
depends on its real-time behavior, delays introduced by a debugger
|
|
might cause the program to change its behavior drastically, or perhaps
|
|
fail, even when the code itself is correct. It is useful to be able
|
|
to observe the program's behavior without interrupting it.
|
|
|
|
Using @value{GDBN}'s @code{trace} and @code{collect} commands, you can
|
|
specify locations in the program, called @dfn{tracepoints}, and
|
|
arbitrary expressions to evaluate when those tracepoints are reached.
|
|
Later, using the @code{tfind} command, you can examine the values
|
|
those expressions had when the program hit the tracepoints. The
|
|
expressions may also denote objects in memory---structures or arrays,
|
|
for example---whose values @value{GDBN} should record; while visiting
|
|
a particular tracepoint, you may inspect those objects as if they were
|
|
in memory at that moment. However, because @value{GDBN} records these
|
|
values without interacting with you, it can do so quickly and
|
|
unobtrusively, hopefully not disturbing the program's behavior.
|
|
|
|
The tracepoint facility is currently available only for remote
|
|
targets. @xref{Targets}. In addition, your remote target must know
|
|
how to collect trace data. This functionality is implemented in the
|
|
remote stub; however, none of the stubs distributed with @value{GDBN}
|
|
support tracepoints as of this writing. The format of the remote
|
|
packets used to implement tracepoints are described in @ref{Tracepoint
|
|
Packets}.
|
|
|
|
It is also possible to get trace data from a file, in a manner reminiscent
|
|
of corefiles; you specify the filename, and use @code{tfind} to search
|
|
through the file. @xref{Trace Files}, for more details.
|
|
|
|
This chapter describes the tracepoint commands and features.
|
|
|
|
@menu
|
|
* Set Tracepoints::
|
|
* Analyze Collected Data::
|
|
* Tracepoint Variables::
|
|
* Trace Files::
|
|
@end menu
|
|
|
|
@node Set Tracepoints
|
|
@section Commands to Set Tracepoints
|
|
|
|
Before running such a @dfn{trace experiment}, an arbitrary number of
|
|
tracepoints can be set. A tracepoint is actually a special type of
|
|
breakpoint (@pxref{Set Breaks}), so you can manipulate it using
|
|
standard breakpoint commands. For instance, as with breakpoints,
|
|
tracepoint numbers are successive integers starting from one, and many
|
|
of the commands associated with tracepoints take the tracepoint number
|
|
as their argument, to identify which tracepoint to work on.
|
|
|
|
For each tracepoint, you can specify, in advance, some arbitrary set
|
|
of data that you want the target to collect in the trace buffer when
|
|
it hits that tracepoint. The collected data can include registers,
|
|
local variables, or global data. Later, you can use @value{GDBN}
|
|
commands to examine the values these data had at the time the
|
|
tracepoint was hit.
|
|
|
|
Tracepoints do not support every breakpoint feature. Ignore counts on
|
|
tracepoints have no effect, and tracepoints cannot run @value{GDBN}
|
|
commands when they are hit. Tracepoints may not be thread-specific
|
|
either.
|
|
|
|
@cindex fast tracepoints
|
|
Some targets may support @dfn{fast tracepoints}, which are inserted in
|
|
a different way (such as with a jump instead of a trap), that is
|
|
faster but possibly restricted in where they may be installed.
|
|
|
|
@cindex static tracepoints
|
|
@cindex markers, static tracepoints
|
|
@cindex probing markers, static tracepoints
|
|
Regular and fast tracepoints are dynamic tracing facilities, meaning
|
|
that they can be used to insert tracepoints at (almost) any location
|
|
in the target. Some targets may also support controlling @dfn{static
|
|
tracepoints} from @value{GDBN}. With static tracing, a set of
|
|
instrumentation points, also known as @dfn{markers}, are embedded in
|
|
the target program, and can be activated or deactivated by name or
|
|
address. These are usually placed at locations which facilitate
|
|
investigating what the target is actually doing. @value{GDBN}'s
|
|
support for static tracing includes being able to list instrumentation
|
|
points, and attach them with @value{GDBN} defined high level
|
|
tracepoints that expose the whole range of convenience of
|
|
@value{GDBN}'s tracepoints support. Namely, support for collecting
|
|
registers values and values of global or local (to the instrumentation
|
|
point) variables; tracepoint conditions and trace state variables.
|
|
The act of installing a @value{GDBN} static tracepoint on an
|
|
instrumentation point, or marker, is referred to as @dfn{probing} a
|
|
static tracepoint marker.
|
|
|
|
@code{gdbserver} supports tracepoints on some target systems.
|
|
@xref{Server,,Tracepoints support in @code{gdbserver}}.
|
|
|
|
This section describes commands to set tracepoints and associated
|
|
conditions and actions.
|
|
|
|
@menu
|
|
* Create and Delete Tracepoints::
|
|
* Enable and Disable Tracepoints::
|
|
* Tracepoint Passcounts::
|
|
* Tracepoint Conditions::
|
|
* Trace State Variables::
|
|
* Tracepoint Actions::
|
|
* Listing Tracepoints::
|
|
* Listing Static Tracepoint Markers::
|
|
* Starting and Stopping Trace Experiments::
|
|
* Tracepoint Restrictions::
|
|
@end menu
|
|
|
|
@node Create and Delete Tracepoints
|
|
@subsection Create and Delete Tracepoints
|
|
|
|
@table @code
|
|
@cindex set tracepoint
|
|
@kindex trace
|
|
@item trace @var{location}
|
|
The @code{trace} command is very similar to the @code{break} command.
|
|
Its argument @var{location} can be a source line, a function name, or
|
|
an address in the target program. @xref{Specify Location}. The
|
|
@code{trace} command defines a tracepoint, which is a point in the
|
|
target program where the debugger will briefly stop, collect some
|
|
data, and then allow the program to continue. Setting a tracepoint or
|
|
changing its actions takes effect immediately if the remote stub
|
|
supports the @samp{InstallInTrace} feature (@pxref{install tracepoint
|
|
in tracing}).
|
|
If remote stub doesn't support the @samp{InstallInTrace} feature, all
|
|
these changes don't take effect until the next @code{tstart}
|
|
command, and once a trace experiment is running, further changes will
|
|
not have any effect until the next trace experiment starts. In addition,
|
|
@value{GDBN} supports @dfn{pending tracepoints}---tracepoints whose
|
|
address is not yet resolved. (This is similar to pending breakpoints.)
|
|
Pending tracepoints are not downloaded to the target and not installed
|
|
until they are resolved. The resolution of pending tracepoints requires
|
|
@value{GDBN} support---when debugging with the remote target, and
|
|
@value{GDBN} disconnects from the remote stub (@pxref{disconnected
|
|
tracing}), pending tracepoints can not be resolved (and downloaded to
|
|
the remote stub) while @value{GDBN} is disconnected.
|
|
|
|
Here are some examples of using the @code{trace} command:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) @b{trace foo.c:121} // a source file and line number
|
|
|
|
(@value{GDBP}) @b{trace +2} // 2 lines forward
|
|
|
|
(@value{GDBP}) @b{trace my_function} // first source line of function
|
|
|
|
(@value{GDBP}) @b{trace *my_function} // EXACT start address of function
|
|
|
|
(@value{GDBP}) @b{trace *0x2117c4} // an address
|
|
@end smallexample
|
|
|
|
@noindent
|
|
You can abbreviate @code{trace} as @code{tr}.
|
|
|
|
@item trace @var{location} if @var{cond}
|
|
Set a tracepoint with condition @var{cond}; evaluate the expression
|
|
@var{cond} each time the tracepoint is reached, and collect data only
|
|
if the value is nonzero---that is, if @var{cond} evaluates as true.
|
|
@xref{Tracepoint Conditions, ,Tracepoint Conditions}, for more
|
|
information on tracepoint conditions.
|
|
|
|
@item ftrace @var{location} [ if @var{cond} ]
|
|
@cindex set fast tracepoint
|
|
@cindex fast tracepoints, setting
|
|
@kindex ftrace
|
|
The @code{ftrace} command sets a fast tracepoint. For targets that
|
|
support them, fast tracepoints will use a more efficient but possibly
|
|
less general technique to trigger data collection, such as a jump
|
|
instruction instead of a trap, or some sort of hardware support. It
|
|
may not be possible to create a fast tracepoint at the desired
|
|
location, in which case the command will exit with an explanatory
|
|
message.
|
|
|
|
@value{GDBN} handles arguments to @code{ftrace} exactly as for
|
|
@code{trace}.
|
|
|
|
On 32-bit x86-architecture systems, fast tracepoints normally need to
|
|
be placed at an instruction that is 5 bytes or longer, but can be
|
|
placed at 4-byte instructions if the low 64K of memory of the target
|
|
program is available to install trampolines. Some Unix-type systems,
|
|
such as @sc{gnu}/Linux, exclude low addresses from the program's
|
|
address space; but for instance with the Linux kernel it is possible
|
|
to let @value{GDBN} use this area by doing a @command{sysctl} command
|
|
to set the @code{mmap_min_addr} kernel parameter, as in
|
|
|
|
@example
|
|
sudo sysctl -w vm.mmap_min_addr=32768
|
|
@end example
|
|
|
|
@noindent
|
|
which sets the low address to 32K, which leaves plenty of room for
|
|
trampolines. The minimum address should be set to a page boundary.
|
|
|
|
@item strace @var{location} [ if @var{cond} ]
|
|
@cindex set static tracepoint
|
|
@cindex static tracepoints, setting
|
|
@cindex probe static tracepoint marker
|
|
@kindex strace
|
|
The @code{strace} command sets a static tracepoint. For targets that
|
|
support it, setting a static tracepoint probes a static
|
|
instrumentation point, or marker, found at @var{location}. It may not
|
|
be possible to set a static tracepoint at the desired location, in
|
|
which case the command will exit with an explanatory message.
|
|
|
|
@value{GDBN} handles arguments to @code{strace} exactly as for
|
|
@code{trace}, with the addition that the user can also specify
|
|
@code{-m @var{marker}} as @var{location}. This probes the marker
|
|
identified by the @var{marker} string identifier. This identifier
|
|
depends on the static tracepoint backend library your program is
|
|
using. You can find all the marker identifiers in the @samp{ID} field
|
|
of the @code{info static-tracepoint-markers} command output.
|
|
@xref{Listing Static Tracepoint Markers,,Listing Static Tracepoint
|
|
Markers}. For example, in the following small program using the UST
|
|
tracing engine:
|
|
|
|
@smallexample
|
|
main ()
|
|
@{
|
|
trace_mark(ust, bar33, "str %s", "FOOBAZ");
|
|
@}
|
|
@end smallexample
|
|
|
|
@noindent
|
|
the marker id is composed of joining the first two arguments to the
|
|
@code{trace_mark} call with a slash, which translates to:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) info static-tracepoint-markers
|
|
Cnt Enb ID Address What
|
|
1 n ust/bar33 0x0000000000400ddc in main at stexample.c:22
|
|
Data: "str %s"
|
|
[etc...]
|
|
@end smallexample
|
|
|
|
@noindent
|
|
so you may probe the marker above with:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) strace -m ust/bar33
|
|
@end smallexample
|
|
|
|
Static tracepoints accept an extra collect action --- @code{collect
|
|
$_sdata}. This collects arbitrary user data passed in the probe point
|
|
call to the tracing library. In the UST example above, you'll see
|
|
that the third argument to @code{trace_mark} is a printf-like format
|
|
string. The user data is then the result of running that formating
|
|
string against the following arguments. Note that @code{info
|
|
static-tracepoint-markers} command output lists that format string in
|
|
the @samp{Data:} field.
|
|
|
|
You can inspect this data when analyzing the trace buffer, by printing
|
|
the $_sdata variable like any other variable available to
|
|
@value{GDBN}. @xref{Tracepoint Actions,,Tracepoint Action Lists}.
|
|
|
|
@vindex $tpnum
|
|
@cindex last tracepoint number
|
|
@cindex recent tracepoint number
|
|
@cindex tracepoint number
|
|
The convenience variable @code{$tpnum} records the tracepoint number
|
|
of the most recently set tracepoint.
|
|
|
|
@kindex delete tracepoint
|
|
@cindex tracepoint deletion
|
|
@item delete tracepoint @r{[}@var{num}@r{]}
|
|
Permanently delete one or more tracepoints. With no argument, the
|
|
default is to delete all tracepoints. Note that the regular
|
|
@code{delete} command can remove tracepoints also.
|
|
|
|
Examples:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) @b{delete trace 1 2 3} // remove three tracepoints
|
|
|
|
(@value{GDBP}) @b{delete trace} // remove all tracepoints
|
|
@end smallexample
|
|
|
|
@noindent
|
|
You can abbreviate this command as @code{del tr}.
|
|
@end table
|
|
|
|
@node Enable and Disable Tracepoints
|
|
@subsection Enable and Disable Tracepoints
|
|
|
|
These commands are deprecated; they are equivalent to plain @code{disable} and @code{enable}.
|
|
|
|
@table @code
|
|
@kindex disable tracepoint
|
|
@item disable tracepoint @r{[}@var{num}@r{]}
|
|
Disable tracepoint @var{num}, or all tracepoints if no argument
|
|
@var{num} is given. A disabled tracepoint will have no effect during
|
|
a trace experiment, but it is not forgotten. You can re-enable
|
|
a disabled tracepoint using the @code{enable tracepoint} command.
|
|
If the command is issued during a trace experiment and the debug target
|
|
has support for disabling tracepoints during a trace experiment, then the
|
|
change will be effective immediately. Otherwise, it will be applied to the
|
|
next trace experiment.
|
|
|
|
@kindex enable tracepoint
|
|
@item enable tracepoint @r{[}@var{num}@r{]}
|
|
Enable tracepoint @var{num}, or all tracepoints. If this command is
|
|
issued during a trace experiment and the debug target supports enabling
|
|
tracepoints during a trace experiment, then the enabled tracepoints will
|
|
become effective immediately. Otherwise, they will become effective the
|
|
next time a trace experiment is run.
|
|
@end table
|
|
|
|
@node Tracepoint Passcounts
|
|
@subsection Tracepoint Passcounts
|
|
|
|
@table @code
|
|
@kindex passcount
|
|
@cindex tracepoint pass count
|
|
@item passcount @r{[}@var{n} @r{[}@var{num}@r{]]}
|
|
Set the @dfn{passcount} of a tracepoint. The passcount is a way to
|
|
automatically stop a trace experiment. If a tracepoint's passcount is
|
|
@var{n}, then the trace experiment will be automatically stopped on
|
|
the @var{n}'th time that tracepoint is hit. If the tracepoint number
|
|
@var{num} is not specified, the @code{passcount} command sets the
|
|
passcount of the most recently defined tracepoint. If no passcount is
|
|
given, the trace experiment will run until stopped explicitly by the
|
|
user.
|
|
|
|
Examples:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) @b{passcount 5 2} // Stop on the 5th execution of
|
|
@exdent @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @code{// tracepoint 2}
|
|
|
|
(@value{GDBP}) @b{passcount 12} // Stop on the 12th execution of the
|
|
@exdent @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @code{// most recently defined tracepoint.}
|
|
(@value{GDBP}) @b{trace foo}
|
|
(@value{GDBP}) @b{pass 3}
|
|
(@value{GDBP}) @b{trace bar}
|
|
(@value{GDBP}) @b{pass 2}
|
|
(@value{GDBP}) @b{trace baz}
|
|
(@value{GDBP}) @b{pass 1} // Stop tracing when foo has been
|
|
@exdent @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @code{// executed 3 times OR when bar has}
|
|
@exdent @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @code{// been executed 2 times}
|
|
@exdent @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @code{// OR when baz has been executed 1 time.}
|
|
@end smallexample
|
|
@end table
|
|
|
|
@node Tracepoint Conditions
|
|
@subsection Tracepoint Conditions
|
|
@cindex conditional tracepoints
|
|
@cindex tracepoint conditions
|
|
|
|
The simplest sort of tracepoint collects data every time your program
|
|
reaches a specified place. You can also specify a @dfn{condition} for
|
|
a tracepoint. A condition is just a Boolean expression in your
|
|
programming language (@pxref{Expressions, ,Expressions}). A
|
|
tracepoint with a condition evaluates the expression each time your
|
|
program reaches it, and data collection happens only if the condition
|
|
is true.
|
|
|
|
Tracepoint conditions can be specified when a tracepoint is set, by
|
|
using @samp{if} in the arguments to the @code{trace} command.
|
|
@xref{Create and Delete Tracepoints, ,Setting Tracepoints}. They can
|
|
also be set or changed at any time with the @code{condition} command,
|
|
just as with breakpoints.
|
|
|
|
Unlike breakpoint conditions, @value{GDBN} does not actually evaluate
|
|
the conditional expression itself. Instead, @value{GDBN} encodes the
|
|
expression into an agent expression (@pxref{Agent Expressions})
|
|
suitable for execution on the target, independently of @value{GDBN}.
|
|
Global variables become raw memory locations, locals become stack
|
|
accesses, and so forth.
|
|
|
|
For instance, suppose you have a function that is usually called
|
|
frequently, but should not be called after an error has occurred. You
|
|
could use the following tracepoint command to collect data about calls
|
|
of that function that happen while the error code is propagating
|
|
through the program; an unconditional tracepoint could end up
|
|
collecting thousands of useless trace frames that you would have to
|
|
search through.
|
|
|
|
@smallexample
|
|
(@value{GDBP}) @kbd{trace normal_operation if errcode > 0}
|
|
@end smallexample
|
|
|
|
@node Trace State Variables
|
|
@subsection Trace State Variables
|
|
@cindex trace state variables
|
|
|
|
A @dfn{trace state variable} is a special type of variable that is
|
|
created and managed by target-side code. The syntax is the same as
|
|
that for GDB's convenience variables (a string prefixed with ``$''),
|
|
but they are stored on the target. They must be created explicitly,
|
|
using a @code{tvariable} command. They are always 64-bit signed
|
|
integers.
|
|
|
|
Trace state variables are remembered by @value{GDBN}, and downloaded
|
|
to the target along with tracepoint information when the trace
|
|
experiment starts. There are no intrinsic limits on the number of
|
|
trace state variables, beyond memory limitations of the target.
|
|
|
|
@cindex convenience variables, and trace state variables
|
|
Although trace state variables are managed by the target, you can use
|
|
them in print commands and expressions as if they were convenience
|
|
variables; @value{GDBN} will get the current value from the target
|
|
while the trace experiment is running. Trace state variables share
|
|
the same namespace as other ``$'' variables, which means that you
|
|
cannot have trace state variables with names like @code{$23} or
|
|
@code{$pc}, nor can you have a trace state variable and a convenience
|
|
variable with the same name.
|
|
|
|
@table @code
|
|
|
|
@item tvariable $@var{name} [ = @var{expression} ]
|
|
@kindex tvariable
|
|
The @code{tvariable} command creates a new trace state variable named
|
|
@code{$@var{name}}, and optionally gives it an initial value of
|
|
@var{expression}. @var{expression} is evaluated when this command is
|
|
entered; the result will be converted to an integer if possible,
|
|
otherwise @value{GDBN} will report an error. A subsequent
|
|
@code{tvariable} command specifying the same name does not create a
|
|
variable, but instead assigns the supplied initial value to the
|
|
existing variable of that name, overwriting any previous initial
|
|
value. The default initial value is 0.
|
|
|
|
@item info tvariables
|
|
@kindex info tvariables
|
|
List all the trace state variables along with their initial values.
|
|
Their current values may also be displayed, if the trace experiment is
|
|
currently running.
|
|
|
|
@item delete tvariable @r{[} $@var{name} @dots{} @r{]}
|
|
@kindex delete tvariable
|
|
Delete the given trace state variables, or all of them if no arguments
|
|
are specified.
|
|
|
|
@end table
|
|
|
|
@node Tracepoint Actions
|
|
@subsection Tracepoint Action Lists
|
|
|
|
@table @code
|
|
@kindex actions
|
|
@cindex tracepoint actions
|
|
@item actions @r{[}@var{num}@r{]}
|
|
This command will prompt for a list of actions to be taken when the
|
|
tracepoint is hit. If the tracepoint number @var{num} is not
|
|
specified, this command sets the actions for the one that was most
|
|
recently defined (so that you can define a tracepoint and then say
|
|
@code{actions} without bothering about its number). You specify the
|
|
actions themselves on the following lines, one action at a time, and
|
|
terminate the actions list with a line containing just @code{end}. So
|
|
far, the only defined actions are @code{collect}, @code{teval}, and
|
|
@code{while-stepping}.
|
|
|
|
@code{actions} is actually equivalent to @code{commands} (@pxref{Break
|
|
Commands, ,Breakpoint Command Lists}), except that only the defined
|
|
actions are allowed; any other @value{GDBN} command is rejected.
|
|
|
|
@cindex remove actions from a tracepoint
|
|
To remove all actions from a tracepoint, type @samp{actions @var{num}}
|
|
and follow it immediately with @samp{end}.
|
|
|
|
@smallexample
|
|
(@value{GDBP}) @b{collect @var{data}} // collect some data
|
|
|
|
(@value{GDBP}) @b{while-stepping 5} // single-step 5 times, collect data
|
|
|
|
(@value{GDBP}) @b{end} // signals the end of actions.
|
|
@end smallexample
|
|
|
|
In the following example, the action list begins with @code{collect}
|
|
commands indicating the things to be collected when the tracepoint is
|
|
hit. Then, in order to single-step and collect additional data
|
|
following the tracepoint, a @code{while-stepping} command is used,
|
|
followed by the list of things to be collected after each step in a
|
|
sequence of single steps. The @code{while-stepping} command is
|
|
terminated by its own separate @code{end} command. Lastly, the action
|
|
list is terminated by an @code{end} command.
|
|
|
|
@smallexample
|
|
(@value{GDBP}) @b{trace foo}
|
|
(@value{GDBP}) @b{actions}
|
|
Enter actions for tracepoint 1, one per line:
|
|
> collect bar,baz
|
|
> collect $regs
|
|
> while-stepping 12
|
|
> collect $pc, arr[i]
|
|
> end
|
|
end
|
|
@end smallexample
|
|
|
|
@kindex collect @r{(tracepoints)}
|
|
@item collect@r{[}/@var{mods}@r{]} @var{expr1}, @var{expr2}, @dots{}
|
|
Collect values of the given expressions when the tracepoint is hit.
|
|
This command accepts a comma-separated list of any valid expressions.
|
|
In addition to global, static, or local variables, the following
|
|
special arguments are supported:
|
|
|
|
@table @code
|
|
@item $regs
|
|
Collect all registers.
|
|
|
|
@item $args
|
|
Collect all function arguments.
|
|
|
|
@item $locals
|
|
Collect all local variables.
|
|
|
|
@item $_ret
|
|
Collect the return address. This is helpful if you want to see more
|
|
of a backtrace.
|
|
|
|
@item $_probe_argc
|
|
Collects the number of arguments from the static probe at which the
|
|
tracepoint is located.
|
|
@xref{Static Probe Points}.
|
|
|
|
@item $_probe_arg@var{n}
|
|
@var{n} is an integer between 0 and 11. Collects the @var{n}th argument
|
|
from the static probe at which the tracepoint is located.
|
|
@xref{Static Probe Points}.
|
|
|
|
@item $_sdata
|
|
@vindex $_sdata@r{, collect}
|
|
Collect static tracepoint marker specific data. Only available for
|
|
static tracepoints. @xref{Tracepoint Actions,,Tracepoint Action
|
|
Lists}. On the UST static tracepoints library backend, an
|
|
instrumentation point resembles a @code{printf} function call. The
|
|
tracing library is able to collect user specified data formatted to a
|
|
character string using the format provided by the programmer that
|
|
instrumented the program. Other backends have similar mechanisms.
|
|
Here's an example of a UST marker call:
|
|
|
|
@smallexample
|
|
const char master_name[] = "$your_name";
|
|
trace_mark(channel1, marker1, "hello %s", master_name)
|
|
@end smallexample
|
|
|
|
In this case, collecting @code{$_sdata} collects the string
|
|
@samp{hello $yourname}. When analyzing the trace buffer, you can
|
|
inspect @samp{$_sdata} like any other variable available to
|
|
@value{GDBN}.
|
|
@end table
|
|
|
|
You can give several consecutive @code{collect} commands, each one
|
|
with a single argument, or one @code{collect} command with several
|
|
arguments separated by commas; the effect is the same.
|
|
|
|
The optional @var{mods} changes the usual handling of the arguments.
|
|
@code{s} requests that pointers to chars be handled as strings, in
|
|
particular collecting the contents of the memory being pointed at, up
|
|
to the first zero. The upper bound is by default the value of the
|
|
@code{print elements} variable; if @code{s} is followed by a decimal
|
|
number, that is the upper bound instead. So for instance
|
|
@samp{collect/s25 mystr} collects as many as 25 characters at
|
|
@samp{mystr}.
|
|
|
|
The command @code{info scope} (@pxref{Symbols, info scope}) is
|
|
particularly useful for figuring out what data to collect.
|
|
|
|
@kindex teval @r{(tracepoints)}
|
|
@item teval @var{expr1}, @var{expr2}, @dots{}
|
|
Evaluate the given expressions when the tracepoint is hit. This
|
|
command accepts a comma-separated list of expressions. The results
|
|
are discarded, so this is mainly useful for assigning values to trace
|
|
state variables (@pxref{Trace State Variables}) without adding those
|
|
values to the trace buffer, as would be the case if the @code{collect}
|
|
action were used.
|
|
|
|
@kindex while-stepping @r{(tracepoints)}
|
|
@item while-stepping @var{n}
|
|
Perform @var{n} single-step instruction traces after the tracepoint,
|
|
collecting new data after each step. The @code{while-stepping}
|
|
command is followed by the list of what to collect while stepping
|
|
(followed by its own @code{end} command):
|
|
|
|
@smallexample
|
|
> while-stepping 12
|
|
> collect $regs, myglobal
|
|
> end
|
|
>
|
|
@end smallexample
|
|
|
|
@noindent
|
|
Note that @code{$pc} is not automatically collected by
|
|
@code{while-stepping}; you need to explicitly collect that register if
|
|
you need it. You may abbreviate @code{while-stepping} as @code{ws} or
|
|
@code{stepping}.
|
|
|
|
@item set default-collect @var{expr1}, @var{expr2}, @dots{}
|
|
@kindex set default-collect
|
|
@cindex default collection action
|
|
This variable is a list of expressions to collect at each tracepoint
|
|
hit. It is effectively an additional @code{collect} action prepended
|
|
to every tracepoint action list. The expressions are parsed
|
|
individually for each tracepoint, so for instance a variable named
|
|
@code{xyz} may be interpreted as a global for one tracepoint, and a
|
|
local for another, as appropriate to the tracepoint's location.
|
|
|
|
@item show default-collect
|
|
@kindex show default-collect
|
|
Show the list of expressions that are collected by default at each
|
|
tracepoint hit.
|
|
|
|
@end table
|
|
|
|
@node Listing Tracepoints
|
|
@subsection Listing Tracepoints
|
|
|
|
@table @code
|
|
@kindex info tracepoints @r{[}@var{n}@dots{}@r{]}
|
|
@kindex info tp @r{[}@var{n}@dots{}@r{]}
|
|
@cindex information about tracepoints
|
|
@item info tracepoints @r{[}@var{num}@dots{}@r{]}
|
|
Display information about the tracepoint @var{num}. If you don't
|
|
specify a tracepoint number, displays information about all the
|
|
tracepoints defined so far. The format is similar to that used for
|
|
@code{info breakpoints}; in fact, @code{info tracepoints} is the same
|
|
command, simply restricting itself to tracepoints.
|
|
|
|
A tracepoint's listing may include additional information specific to
|
|
tracing:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
its passcount as given by the @code{passcount @var{n}} command
|
|
@end itemize
|
|
|
|
@smallexample
|
|
(@value{GDBP}) @b{info trace}
|
|
Num Type Disp Enb Address What
|
|
1 tracepoint keep y 0x0804ab57 in foo() at main.cxx:7
|
|
while-stepping 20
|
|
collect globfoo, $regs
|
|
end
|
|
collect globfoo2
|
|
end
|
|
pass count 1200
|
|
(@value{GDBP})
|
|
@end smallexample
|
|
|
|
@noindent
|
|
This command can be abbreviated @code{info tp}.
|
|
@end table
|
|
|
|
@node Listing Static Tracepoint Markers
|
|
@subsection Listing Static Tracepoint Markers
|
|
|
|
@table @code
|
|
@kindex info static-tracepoint-markers
|
|
@cindex information about static tracepoint markers
|
|
@item info static-tracepoint-markers
|
|
Display information about all static tracepoint markers defined in the
|
|
program.
|
|
|
|
For each marker, the following columns are printed:
|
|
|
|
@table @emph
|
|
@item Count
|
|
An incrementing counter, output to help readability. This is not a
|
|
stable identifier.
|
|
@item ID
|
|
The marker ID, as reported by the target.
|
|
@item Enabled or Disabled
|
|
Probed markers are tagged with @samp{y}. @samp{n} identifies marks
|
|
that are not enabled.
|
|
@item Address
|
|
Where the marker is in your program, as a memory address.
|
|
@item What
|
|
Where the marker is in the source for your program, as a file and line
|
|
number. If the debug information included in the program does not
|
|
allow @value{GDBN} to locate the source of the marker, this column
|
|
will be left blank.
|
|
@end table
|
|
|
|
@noindent
|
|
In addition, the following information may be printed for each marker:
|
|
|
|
@table @emph
|
|
@item Data
|
|
User data passed to the tracing library by the marker call. In the
|
|
UST backend, this is the format string passed as argument to the
|
|
marker call.
|
|
@item Static tracepoints probing the marker
|
|
The list of static tracepoints attached to the marker.
|
|
@end table
|
|
|
|
@smallexample
|
|
(@value{GDBP}) info static-tracepoint-markers
|
|
Cnt ID Enb Address What
|
|
1 ust/bar2 y 0x0000000000400e1a in main at stexample.c:25
|
|
Data: number1 %d number2 %d
|
|
Probed by static tracepoints: #2
|
|
2 ust/bar33 n 0x0000000000400c87 in main at stexample.c:24
|
|
Data: str %s
|
|
(@value{GDBP})
|
|
@end smallexample
|
|
@end table
|
|
|
|
@node Starting and Stopping Trace Experiments
|
|
@subsection Starting and Stopping Trace Experiments
|
|
|
|
@table @code
|
|
@kindex tstart [ @var{notes} ]
|
|
@cindex start a new trace experiment
|
|
@cindex collected data discarded
|
|
@item tstart
|
|
This command starts the trace experiment, and begins collecting data.
|
|
It has the side effect of discarding all the data collected in the
|
|
trace buffer during the previous trace experiment. If any arguments
|
|
are supplied, they are taken as a note and stored with the trace
|
|
experiment's state. The notes may be arbitrary text, and are
|
|
especially useful with disconnected tracing in a multi-user context;
|
|
the notes can explain what the trace is doing, supply user contact
|
|
information, and so forth.
|
|
|
|
@kindex tstop [ @var{notes} ]
|
|
@cindex stop a running trace experiment
|
|
@item tstop
|
|
This command stops the trace experiment. If any arguments are
|
|
supplied, they are recorded with the experiment as a note. This is
|
|
useful if you are stopping a trace started by someone else, for
|
|
instance if the trace is interfering with the system's behavior and
|
|
needs to be stopped quickly.
|
|
|
|
@strong{Note}: a trace experiment and data collection may stop
|
|
automatically if any tracepoint's passcount is reached
|
|
(@pxref{Tracepoint Passcounts}), or if the trace buffer becomes full.
|
|
|
|
@kindex tstatus
|
|
@cindex status of trace data collection
|
|
@cindex trace experiment, status of
|
|
@item tstatus
|
|
This command displays the status of the current trace data
|
|
collection.
|
|
@end table
|
|
|
|
Here is an example of the commands we described so far:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) @b{trace gdb_c_test}
|
|
(@value{GDBP}) @b{actions}
|
|
Enter actions for tracepoint #1, one per line.
|
|
> collect $regs,$locals,$args
|
|
> while-stepping 11
|
|
> collect $regs
|
|
> end
|
|
> end
|
|
(@value{GDBP}) @b{tstart}
|
|
[time passes @dots{}]
|
|
(@value{GDBP}) @b{tstop}
|
|
@end smallexample
|
|
|
|
@anchor{disconnected tracing}
|
|
@cindex disconnected tracing
|
|
You can choose to continue running the trace experiment even if
|
|
@value{GDBN} disconnects from the target, voluntarily or
|
|
involuntarily. For commands such as @code{detach}, the debugger will
|
|
ask what you want to do with the trace. But for unexpected
|
|
terminations (@value{GDBN} crash, network outage), it would be
|
|
unfortunate to lose hard-won trace data, so the variable
|
|
@code{disconnected-tracing} lets you decide whether the trace should
|
|
continue running without @value{GDBN}.
|
|
|
|
@table @code
|
|
@item set disconnected-tracing on
|
|
@itemx set disconnected-tracing off
|
|
@kindex set disconnected-tracing
|
|
Choose whether a tracing run should continue to run if @value{GDBN}
|
|
has disconnected from the target. Note that @code{detach} or
|
|
@code{quit} will ask you directly what to do about a running trace no
|
|
matter what this variable's setting, so the variable is mainly useful
|
|
for handling unexpected situations, such as loss of the network.
|
|
|
|
@item show disconnected-tracing
|
|
@kindex show disconnected-tracing
|
|
Show the current choice for disconnected tracing.
|
|
|
|
@end table
|
|
|
|
When you reconnect to the target, the trace experiment may or may not
|
|
still be running; it might have filled the trace buffer in the
|
|
meantime, or stopped for one of the other reasons. If it is running,
|
|
it will continue after reconnection.
|
|
|
|
Upon reconnection, the target will upload information about the
|
|
tracepoints in effect. @value{GDBN} will then compare that
|
|
information to the set of tracepoints currently defined, and attempt
|
|
to match them up, allowing for the possibility that the numbers may
|
|
have changed due to creation and deletion in the meantime. If one of
|
|
the target's tracepoints does not match any in @value{GDBN}, the
|
|
debugger will create a new tracepoint, so that you have a number with
|
|
which to specify that tracepoint. This matching-up process is
|
|
necessarily heuristic, and it may result in useless tracepoints being
|
|
created; you may simply delete them if they are of no use.
|
|
|
|
@cindex circular trace buffer
|
|
If your target agent supports a @dfn{circular trace buffer}, then you
|
|
can run a trace experiment indefinitely without filling the trace
|
|
buffer; when space runs out, the agent deletes already-collected trace
|
|
frames, oldest first, until there is enough room to continue
|
|
collecting. This is especially useful if your tracepoints are being
|
|
hit too often, and your trace gets terminated prematurely because the
|
|
buffer is full. To ask for a circular trace buffer, simply set
|
|
@samp{circular-trace-buffer} to on. You can set this at any time,
|
|
including during tracing; if the agent can do it, it will change
|
|
buffer handling on the fly, otherwise it will not take effect until
|
|
the next run.
|
|
|
|
@table @code
|
|
@item set circular-trace-buffer on
|
|
@itemx set circular-trace-buffer off
|
|
@kindex set circular-trace-buffer
|
|
Choose whether a tracing run should use a linear or circular buffer
|
|
for trace data. A linear buffer will not lose any trace data, but may
|
|
fill up prematurely, while a circular buffer will discard old trace
|
|
data, but it will have always room for the latest tracepoint hits.
|
|
|
|
@item show circular-trace-buffer
|
|
@kindex show circular-trace-buffer
|
|
Show the current choice for the trace buffer. Note that this may not
|
|
match the agent's current buffer handling, nor is it guaranteed to
|
|
match the setting that might have been in effect during a past run,
|
|
for instance if you are looking at frames from a trace file.
|
|
|
|
@end table
|
|
|
|
@table @code
|
|
@item set trace-user @var{text}
|
|
@kindex set trace-user
|
|
|
|
@item show trace-user
|
|
@kindex show trace-user
|
|
|
|
@item set trace-notes @var{text}
|
|
@kindex set trace-notes
|
|
Set the trace run's notes.
|
|
|
|
@item show trace-notes
|
|
@kindex show trace-notes
|
|
Show the trace run's notes.
|
|
|
|
@item set trace-stop-notes @var{text}
|
|
@kindex set trace-stop-notes
|
|
Set the trace run's stop notes. The handling of the note is as for
|
|
@code{tstop} arguments; the set command is convenient way to fix a
|
|
stop note that is mistaken or incomplete.
|
|
|
|
@item show trace-stop-notes
|
|
@kindex show trace-stop-notes
|
|
Show the trace run's stop notes.
|
|
|
|
@end table
|
|
|
|
@node Tracepoint Restrictions
|
|
@subsection Tracepoint Restrictions
|
|
|
|
@cindex tracepoint restrictions
|
|
There are a number of restrictions on the use of tracepoints. As
|
|
described above, tracepoint data gathering occurs on the target
|
|
without interaction from @value{GDBN}. Thus the full capabilities of
|
|
the debugger are not available during data gathering, and then at data
|
|
examination time, you will be limited by only having what was
|
|
collected. The following items describe some common problems, but it
|
|
is not exhaustive, and you may run into additional difficulties not
|
|
mentioned here.
|
|
|
|
@itemize @bullet
|
|
|
|
@item
|
|
Tracepoint expressions are intended to gather objects (lvalues). Thus
|
|
the full flexibility of GDB's expression evaluator is not available.
|
|
You cannot call functions, cast objects to aggregate types, access
|
|
convenience variables or modify values (except by assignment to trace
|
|
state variables). Some language features may implicitly call
|
|
functions (for instance Objective-C fields with accessors), and therefore
|
|
cannot be collected either.
|
|
|
|
@item
|
|
Collection of local variables, either individually or in bulk with
|
|
@code{$locals} or @code{$args}, during @code{while-stepping} may
|
|
behave erratically. The stepping action may enter a new scope (for
|
|
instance by stepping into a function), or the location of the variable
|
|
may change (for instance it is loaded into a register). The
|
|
tracepoint data recorded uses the location information for the
|
|
variables that is correct for the tracepoint location. When the
|
|
tracepoint is created, it is not possible, in general, to determine
|
|
where the steps of a @code{while-stepping} sequence will advance the
|
|
program---particularly if a conditional branch is stepped.
|
|
|
|
@item
|
|
Collection of an incompletely-initialized or partially-destroyed object
|
|
may result in something that @value{GDBN} cannot display, or displays
|
|
in a misleading way.
|
|
|
|
@item
|
|
When @value{GDBN} displays a pointer to character it automatically
|
|
dereferences the pointer to also display characters of the string
|
|
being pointed to. However, collecting the pointer during tracing does
|
|
not automatically collect the string. You need to explicitly
|
|
dereference the pointer and provide size information if you want to
|
|
collect not only the pointer, but the memory pointed to. For example,
|
|
@code{*ptr@@50} can be used to collect the 50 element array pointed to
|
|
by @code{ptr}.
|
|
|
|
@item
|
|
It is not possible to collect a complete stack backtrace at a
|
|
tracepoint. Instead, you may collect the registers and a few hundred
|
|
bytes from the stack pointer with something like @code{*(unsigned char *)$esp@@300}
|
|
(adjust to use the name of the actual stack pointer register on your
|
|
target architecture, and the amount of stack you wish to capture).
|
|
Then the @code{backtrace} command will show a partial backtrace when
|
|
using a trace frame. The number of stack frames that can be examined
|
|
depends on the sizes of the frames in the collected stack. Note that
|
|
if you ask for a block so large that it goes past the bottom of the
|
|
stack, the target agent may report an error trying to read from an
|
|
invalid address.
|
|
|
|
@item
|
|
If you do not collect registers at a tracepoint, @value{GDBN} can
|
|
infer that the value of @code{$pc} must be the same as the address of
|
|
the tracepoint and use that when you are looking at a trace frame
|
|
for that tracepoint. However, this cannot work if the tracepoint has
|
|
multiple locations (for instance if it was set in a function that was
|
|
inlined), or if it has a @code{while-stepping} loop. In those cases
|
|
@value{GDBN} will warn you that it can't infer @code{$pc}, and default
|
|
it to zero.
|
|
|
|
@end itemize
|
|
|
|
@node Analyze Collected Data
|
|
@section Using the Collected Data
|
|
|
|
After the tracepoint experiment ends, you use @value{GDBN} commands
|
|
for examining the trace data. The basic idea is that each tracepoint
|
|
collects a trace @dfn{snapshot} every time it is hit and another
|
|
snapshot every time it single-steps. All these snapshots are
|
|
consecutively numbered from zero and go into a buffer, and you can
|
|
examine them later. The way you examine them is to @dfn{focus} on a
|
|
specific trace snapshot. When the remote stub is focused on a trace
|
|
snapshot, it will respond to all @value{GDBN} requests for memory and
|
|
registers by reading from the buffer which belongs to that snapshot,
|
|
rather than from @emph{real} memory or registers of the program being
|
|
debugged. This means that @strong{all} @value{GDBN} commands
|
|
(@code{print}, @code{info registers}, @code{backtrace}, etc.) will
|
|
behave as if we were currently debugging the program state as it was
|
|
when the tracepoint occurred. Any requests for data that are not in
|
|
the buffer will fail.
|
|
|
|
@menu
|
|
* tfind:: How to select a trace snapshot
|
|
* tdump:: How to display all data for a snapshot
|
|
* save tracepoints:: How to save tracepoints for a future run
|
|
@end menu
|
|
|
|
@node tfind
|
|
@subsection @code{tfind @var{n}}
|
|
|
|
@kindex tfind
|
|
@cindex select trace snapshot
|
|
@cindex find trace snapshot
|
|
The basic command for selecting a trace snapshot from the buffer is
|
|
@code{tfind @var{n}}, which finds trace snapshot number @var{n},
|
|
counting from zero. If no argument @var{n} is given, the next
|
|
snapshot is selected.
|
|
|
|
Here are the various forms of using the @code{tfind} command.
|
|
|
|
@table @code
|
|
@item tfind start
|
|
Find the first snapshot in the buffer. This is a synonym for
|
|
@code{tfind 0} (since 0 is the number of the first snapshot).
|
|
|
|
@item tfind none
|
|
Stop debugging trace snapshots, resume @emph{live} debugging.
|
|
|
|
@item tfind end
|
|
Same as @samp{tfind none}.
|
|
|
|
@item tfind
|
|
No argument means find the next trace snapshot.
|
|
|
|
@item tfind -
|
|
Find the previous trace snapshot before the current one. This permits
|
|
retracing earlier steps.
|
|
|
|
@item tfind tracepoint @var{num}
|
|
Find the next snapshot associated with tracepoint @var{num}. Search
|
|
proceeds forward from the last examined trace snapshot. If no
|
|
argument @var{num} is given, it means find the next snapshot collected
|
|
for the same tracepoint as the current snapshot.
|
|
|
|
@item tfind pc @var{addr}
|
|
Find the next snapshot associated with the value @var{addr} of the
|
|
program counter. Search proceeds forward from the last examined trace
|
|
snapshot. If no argument @var{addr} is given, it means find the next
|
|
snapshot with the same value of PC as the current snapshot.
|
|
|
|
@item tfind outside @var{addr1}, @var{addr2}
|
|
Find the next snapshot whose PC is outside the given range of
|
|
addresses (exclusive).
|
|
|
|
@item tfind range @var{addr1}, @var{addr2}
|
|
Find the next snapshot whose PC is between @var{addr1} and
|
|
@var{addr2} (inclusive).
|
|
|
|
@item tfind line @r{[}@var{file}:@r{]}@var{n}
|
|
Find the next snapshot associated with the source line @var{n}. If
|
|
the optional argument @var{file} is given, refer to line @var{n} in
|
|
that source file. Search proceeds forward from the last examined
|
|
trace snapshot. If no argument @var{n} is given, it means find the
|
|
next line other than the one currently being examined; thus saying
|
|
@code{tfind line} repeatedly can appear to have the same effect as
|
|
stepping from line to line in a @emph{live} debugging session.
|
|
@end table
|
|
|
|
The default arguments for the @code{tfind} commands are specifically
|
|
designed to make it easy to scan through the trace buffer. For
|
|
instance, @code{tfind} with no argument selects the next trace
|
|
snapshot, and @code{tfind -} with no argument selects the previous
|
|
trace snapshot. So, by giving one @code{tfind} command, and then
|
|
simply hitting @key{RET} repeatedly you can examine all the trace
|
|
snapshots in order. Or, by saying @code{tfind -} and then hitting
|
|
@key{RET} repeatedly you can examine the snapshots in reverse order.
|
|
The @code{tfind line} command with no argument selects the snapshot
|
|
for the next source line executed. The @code{tfind pc} command with
|
|
no argument selects the next snapshot with the same program counter
|
|
(PC) as the current frame. The @code{tfind tracepoint} command with
|
|
no argument selects the next trace snapshot collected by the same
|
|
tracepoint as the current one.
|
|
|
|
In addition to letting you scan through the trace buffer manually,
|
|
these commands make it easy to construct @value{GDBN} scripts that
|
|
scan through the trace buffer and print out whatever collected data
|
|
you are interested in. Thus, if we want to examine the PC, FP, and SP
|
|
registers from each trace frame in the buffer, we can say this:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) @b{tfind start}
|
|
(@value{GDBP}) @b{while ($trace_frame != -1)}
|
|
> printf "Frame %d, PC = %08X, SP = %08X, FP = %08X\n", \
|
|
$trace_frame, $pc, $sp, $fp
|
|
> tfind
|
|
> end
|
|
|
|
Frame 0, PC = 0020DC64, SP = 0030BF3C, FP = 0030BF44
|
|
Frame 1, PC = 0020DC6C, SP = 0030BF38, FP = 0030BF44
|
|
Frame 2, PC = 0020DC70, SP = 0030BF34, FP = 0030BF44
|
|
Frame 3, PC = 0020DC74, SP = 0030BF30, FP = 0030BF44
|
|
Frame 4, PC = 0020DC78, SP = 0030BF2C, FP = 0030BF44
|
|
Frame 5, PC = 0020DC7C, SP = 0030BF28, FP = 0030BF44
|
|
Frame 6, PC = 0020DC80, SP = 0030BF24, FP = 0030BF44
|
|
Frame 7, PC = 0020DC84, SP = 0030BF20, FP = 0030BF44
|
|
Frame 8, PC = 0020DC88, SP = 0030BF1C, FP = 0030BF44
|
|
Frame 9, PC = 0020DC8E, SP = 0030BF18, FP = 0030BF44
|
|
Frame 10, PC = 00203F6C, SP = 0030BE3C, FP = 0030BF14
|
|
@end smallexample
|
|
|
|
Or, if we want to examine the variable @code{X} at each source line in
|
|
the buffer:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) @b{tfind start}
|
|
(@value{GDBP}) @b{while ($trace_frame != -1)}
|
|
> printf "Frame %d, X == %d\n", $trace_frame, X
|
|
> tfind line
|
|
> end
|
|
|
|
Frame 0, X = 1
|
|
Frame 7, X = 2
|
|
Frame 13, X = 255
|
|
@end smallexample
|
|
|
|
@node tdump
|
|
@subsection @code{tdump}
|
|
@kindex tdump
|
|
@cindex dump all data collected at tracepoint
|
|
@cindex tracepoint data, display
|
|
|
|
This command takes no arguments. It prints all the data collected at
|
|
the current trace snapshot.
|
|
|
|
@smallexample
|
|
(@value{GDBP}) @b{trace 444}
|
|
(@value{GDBP}) @b{actions}
|
|
Enter actions for tracepoint #2, one per line:
|
|
> collect $regs, $locals, $args, gdb_long_test
|
|
> end
|
|
|
|
(@value{GDBP}) @b{tstart}
|
|
|
|
(@value{GDBP}) @b{tfind line 444}
|
|
#0 gdb_test (p1=0x11, p2=0x22, p3=0x33, p4=0x44, p5=0x55, p6=0x66)
|
|
at gdb_test.c:444
|
|
444 printp( "%s: arguments = 0x%X 0x%X 0x%X 0x%X 0x%X 0x%X\n", )
|
|
|
|
(@value{GDBP}) @b{tdump}
|
|
Data collected at tracepoint 2, trace frame 1:
|
|
d0 0xc4aa0085 -995491707
|
|
d1 0x18 24
|
|
d2 0x80 128
|
|
d3 0x33 51
|
|
d4 0x71aea3d 119204413
|
|
d5 0x22 34
|
|
d6 0xe0 224
|
|
d7 0x380035 3670069
|
|
a0 0x19e24a 1696330
|
|
a1 0x3000668 50333288
|
|
a2 0x100 256
|
|
a3 0x322000 3284992
|
|
a4 0x3000698 50333336
|
|
a5 0x1ad3cc 1758156
|
|
fp 0x30bf3c 0x30bf3c
|
|
sp 0x30bf34 0x30bf34
|
|
ps 0x0 0
|
|
pc 0x20b2c8 0x20b2c8
|
|
fpcontrol 0x0 0
|
|
fpstatus 0x0 0
|
|
fpiaddr 0x0 0
|
|
p = 0x20e5b4 "gdb-test"
|
|
p1 = (void *) 0x11
|
|
p2 = (void *) 0x22
|
|
p3 = (void *) 0x33
|
|
p4 = (void *) 0x44
|
|
p5 = (void *) 0x55
|
|
p6 = (void *) 0x66
|
|
gdb_long_test = 17 '\021'
|
|
|
|
(@value{GDBP})
|
|
@end smallexample
|
|
|
|
@code{tdump} works by scanning the tracepoint's current collection
|
|
actions and printing the value of each expression listed. So
|
|
@code{tdump} can fail, if after a run, you change the tracepoint's
|
|
actions to mention variables that were not collected during the run.
|
|
|
|
Also, for tracepoints with @code{while-stepping} loops, @code{tdump}
|
|
uses the collected value of @code{$pc} to distinguish between trace
|
|
frames that were collected at the tracepoint hit, and frames that were
|
|
collected while stepping. This allows it to correctly choose whether
|
|
to display the basic list of collections, or the collections from the
|
|
body of the while-stepping loop. However, if @code{$pc} was not collected,
|
|
then @code{tdump} will always attempt to dump using the basic collection
|
|
list, and may fail if a while-stepping frame does not include all the
|
|
same data that is collected at the tracepoint hit.
|
|
@c This is getting pretty arcane, example would be good.
|
|
|
|
@node save tracepoints
|
|
@subsection @code{save tracepoints @var{filename}}
|
|
@kindex save tracepoints
|
|
@kindex save-tracepoints
|
|
@cindex save tracepoints for future sessions
|
|
|
|
This command saves all current tracepoint definitions together with
|
|
their actions and passcounts, into a file @file{@var{filename}}
|
|
suitable for use in a later debugging session. To read the saved
|
|
tracepoint definitions, use the @code{source} command (@pxref{Command
|
|
Files}). The @w{@code{save-tracepoints}} command is a deprecated
|
|
alias for @w{@code{save tracepoints}}
|
|
|
|
@node Tracepoint Variables
|
|
@section Convenience Variables for Tracepoints
|
|
@cindex tracepoint variables
|
|
@cindex convenience variables for tracepoints
|
|
|
|
@table @code
|
|
@vindex $trace_frame
|
|
@item (int) $trace_frame
|
|
The current trace snapshot (a.k.a.@: @dfn{frame}) number, or -1 if no
|
|
snapshot is selected.
|
|
|
|
@vindex $tracepoint
|
|
@item (int) $tracepoint
|
|
The tracepoint for the current trace snapshot.
|
|
|
|
@vindex $trace_line
|
|
@item (int) $trace_line
|
|
The line number for the current trace snapshot.
|
|
|
|
@vindex $trace_file
|
|
@item (char []) $trace_file
|
|
The source file for the current trace snapshot.
|
|
|
|
@vindex $trace_func
|
|
@item (char []) $trace_func
|
|
The name of the function containing @code{$tracepoint}.
|
|
@end table
|
|
|
|
Note: @code{$trace_file} is not suitable for use in @code{printf},
|
|
use @code{output} instead.
|
|
|
|
Here's a simple example of using these convenience variables for
|
|
stepping through all the trace snapshots and printing some of their
|
|
data. Note that these are not the same as trace state variables,
|
|
which are managed by the target.
|
|
|
|
@smallexample
|
|
(@value{GDBP}) @b{tfind start}
|
|
|
|
(@value{GDBP}) @b{while $trace_frame != -1}
|
|
> output $trace_file
|
|
> printf ", line %d (tracepoint #%d)\n", $trace_line, $tracepoint
|
|
> tfind
|
|
> end
|
|
@end smallexample
|
|
|
|
@node Trace Files
|
|
@section Using Trace Files
|
|
@cindex trace files
|
|
|
|
In some situations, the target running a trace experiment may no
|
|
longer be available; perhaps it crashed, or the hardware was needed
|
|
for a different activity. To handle these cases, you can arrange to
|
|
dump the trace data into a file, and later use that file as a source
|
|
of trace data, via the @code{target tfile} command.
|
|
|
|
@table @code
|
|
|
|
@kindex tsave
|
|
@item tsave [ -r ] @var{filename}
|
|
Save the trace data to @var{filename}. By default, this command
|
|
assumes that @var{filename} refers to the host filesystem, so if
|
|
necessary @value{GDBN} will copy raw trace data up from the target and
|
|
then save it. If the target supports it, you can also supply the
|
|
optional argument @code{-r} (``remote'') to direct the target to save
|
|
the data directly into @var{filename} in its own filesystem, which may be
|
|
more efficient if the trace buffer is very large. (Note, however, that
|
|
@code{target tfile} can only read from files accessible to the host.)
|
|
|
|
@kindex target tfile
|
|
@kindex tfile
|
|
@item target tfile @var{filename}
|
|
Use the file named @var{filename} as a source of trace data. Commands
|
|
that examine data work as they do with a live target, but it is not
|
|
possible to run any new trace experiments. @code{tstatus} will report
|
|
the state of the trace run at the moment the data was saved, as well
|
|
as the current trace frame you are examining. @var{filename} must be
|
|
on a filesystem accessible to the host.
|
|
|
|
@end table
|
|
|
|
@node Overlays
|
|
@chapter Debugging Programs That Use Overlays
|
|
@cindex overlays
|
|
|
|
If your program is too large to fit completely in your target system's
|
|
memory, you can sometimes use @dfn{overlays} to work around this
|
|
problem. @value{GDBN} provides some support for debugging programs that
|
|
use overlays.
|
|
|
|
@menu
|
|
* How Overlays Work:: A general explanation of overlays.
|
|
* Overlay Commands:: Managing overlays in @value{GDBN}.
|
|
* Automatic Overlay Debugging:: @value{GDBN} can find out which overlays are
|
|
mapped by asking the inferior.
|
|
* Overlay Sample Program:: A sample program using overlays.
|
|
@end menu
|
|
|
|
@node How Overlays Work
|
|
@section How Overlays Work
|
|
@cindex mapped overlays
|
|
@cindex unmapped overlays
|
|
@cindex load address, overlay's
|
|
@cindex mapped address
|
|
@cindex overlay area
|
|
|
|
Suppose you have a computer whose instruction address space is only 64
|
|
kilobytes long, but which has much more memory which can be accessed by
|
|
other means: special instructions, segment registers, or memory
|
|
management hardware, for example. Suppose further that you want to
|
|
adapt a program which is larger than 64 kilobytes to run on this system.
|
|
|
|
One solution is to identify modules of your program which are relatively
|
|
independent, and need not call each other directly; call these modules
|
|
@dfn{overlays}. Separate the overlays from the main program, and place
|
|
their machine code in the larger memory. Place your main program in
|
|
instruction memory, but leave at least enough space there to hold the
|
|
largest overlay as well.
|
|
|
|
Now, to call a function located in an overlay, you must first copy that
|
|
overlay's machine code from the large memory into the space set aside
|
|
for it in the instruction memory, and then jump to its entry point
|
|
there.
|
|
|
|
@c NB: In the below the mapped area's size is greater or equal to the
|
|
@c size of all overlays. This is intentional to remind the developer
|
|
@c that overlays don't necessarily need to be the same size.
|
|
|
|
@smallexample
|
|
@group
|
|
Data Instruction Larger
|
|
Address Space Address Space Address Space
|
|
+-----------+ +-----------+ +-----------+
|
|
| | | | | |
|
|
+-----------+ +-----------+ +-----------+<-- overlay 1
|
|
| program | | main | .----| overlay 1 | load address
|
|
| variables | | program | | +-----------+
|
|
| and heap | | | | | |
|
|
+-----------+ | | | +-----------+<-- overlay 2
|
|
| | +-----------+ | | | load address
|
|
+-----------+ | | | .-| overlay 2 |
|
|
| | | | | |
|
|
mapped --->+-----------+ | | +-----------+
|
|
address | | | | | |
|
|
| overlay | <-' | | |
|
|
| area | <---' +-----------+<-- overlay 3
|
|
| | <---. | | load address
|
|
+-----------+ `--| overlay 3 |
|
|
| | | |
|
|
+-----------+ | |
|
|
+-----------+
|
|
| |
|
|
+-----------+
|
|
|
|
@anchor{A code overlay}A code overlay
|
|
@end group
|
|
@end smallexample
|
|
|
|
The diagram (@pxref{A code overlay}) shows a system with separate data
|
|
and instruction address spaces. To map an overlay, the program copies
|
|
its code from the larger address space to the instruction address space.
|
|
Since the overlays shown here all use the same mapped address, only one
|
|
may be mapped at a time. For a system with a single address space for
|
|
data and instructions, the diagram would be similar, except that the
|
|
program variables and heap would share an address space with the main
|
|
program and the overlay area.
|
|
|
|
An overlay loaded into instruction memory and ready for use is called a
|
|
@dfn{mapped} overlay; its @dfn{mapped address} is its address in the
|
|
instruction memory. An overlay not present (or only partially present)
|
|
in instruction memory is called @dfn{unmapped}; its @dfn{load address}
|
|
is its address in the larger memory. The mapped address is also called
|
|
the @dfn{virtual memory address}, or @dfn{VMA}; the load address is also
|
|
called the @dfn{load memory address}, or @dfn{LMA}.
|
|
|
|
Unfortunately, overlays are not a completely transparent way to adapt a
|
|
program to limited instruction memory. They introduce a new set of
|
|
global constraints you must keep in mind as you design your program:
|
|
|
|
@itemize @bullet
|
|
|
|
@item
|
|
Before calling or returning to a function in an overlay, your program
|
|
must make sure that overlay is actually mapped. Otherwise, the call or
|
|
return will transfer control to the right address, but in the wrong
|
|
overlay, and your program will probably crash.
|
|
|
|
@item
|
|
If the process of mapping an overlay is expensive on your system, you
|
|
will need to choose your overlays carefully to minimize their effect on
|
|
your program's performance.
|
|
|
|
@item
|
|
The executable file you load onto your system must contain each
|
|
overlay's instructions, appearing at the overlay's load address, not its
|
|
mapped address. However, each overlay's instructions must be relocated
|
|
and its symbols defined as if the overlay were at its mapped address.
|
|
You can use GNU linker scripts to specify different load and relocation
|
|
addresses for pieces of your program; see @ref{Overlay Description,,,
|
|
ld.info, Using ld: the GNU linker}.
|
|
|
|
@item
|
|
The procedure for loading executable files onto your system must be able
|
|
to load their contents into the larger address space as well as the
|
|
instruction and data spaces.
|
|
|
|
@end itemize
|
|
|
|
The overlay system described above is rather simple, and could be
|
|
improved in many ways:
|
|
|
|
@itemize @bullet
|
|
|
|
@item
|
|
If your system has suitable bank switch registers or memory management
|
|
hardware, you could use those facilities to make an overlay's load area
|
|
contents simply appear at their mapped address in instruction space.
|
|
This would probably be faster than copying the overlay to its mapped
|
|
area in the usual way.
|
|
|
|
@item
|
|
If your overlays are small enough, you could set aside more than one
|
|
overlay area, and have more than one overlay mapped at a time.
|
|
|
|
@item
|
|
You can use overlays to manage data, as well as instructions. In
|
|
general, data overlays are even less transparent to your design than
|
|
code overlays: whereas code overlays only require care when you call or
|
|
return to functions, data overlays require care every time you access
|
|
the data. Also, if you change the contents of a data overlay, you
|
|
must copy its contents back out to its load address before you can copy a
|
|
different data overlay into the same mapped area.
|
|
|
|
@end itemize
|
|
|
|
|
|
@node Overlay Commands
|
|
@section Overlay Commands
|
|
|
|
To use @value{GDBN}'s overlay support, each overlay in your program must
|
|
correspond to a separate section of the executable file. The section's
|
|
virtual memory address and load memory address must be the overlay's
|
|
mapped and load addresses. Identifying overlays with sections allows
|
|
@value{GDBN} to determine the appropriate address of a function or
|
|
variable, depending on whether the overlay is mapped or not.
|
|
|
|
@value{GDBN}'s overlay commands all start with the word @code{overlay};
|
|
you can abbreviate this as @code{ov} or @code{ovly}. The commands are:
|
|
|
|
@table @code
|
|
@item overlay off
|
|
@kindex overlay
|
|
Disable @value{GDBN}'s overlay support. When overlay support is
|
|
disabled, @value{GDBN} assumes that all functions and variables are
|
|
always present at their mapped addresses. By default, @value{GDBN}'s
|
|
overlay support is disabled.
|
|
|
|
@item overlay manual
|
|
@cindex manual overlay debugging
|
|
Enable @dfn{manual} overlay debugging. In this mode, @value{GDBN}
|
|
relies on you to tell it which overlays are mapped, and which are not,
|
|
using the @code{overlay map-overlay} and @code{overlay unmap-overlay}
|
|
commands described below.
|
|
|
|
@item overlay map-overlay @var{overlay}
|
|
@itemx overlay map @var{overlay}
|
|
@cindex map an overlay
|
|
Tell @value{GDBN} that @var{overlay} is now mapped; @var{overlay} must
|
|
be the name of the object file section containing the overlay. When an
|
|
overlay is mapped, @value{GDBN} assumes it can find the overlay's
|
|
functions and variables at their mapped addresses. @value{GDBN} assumes
|
|
that any other overlays whose mapped ranges overlap that of
|
|
@var{overlay} are now unmapped.
|
|
|
|
@item overlay unmap-overlay @var{overlay}
|
|
@itemx overlay unmap @var{overlay}
|
|
@cindex unmap an overlay
|
|
Tell @value{GDBN} that @var{overlay} is no longer mapped; @var{overlay}
|
|
must be the name of the object file section containing the overlay.
|
|
When an overlay is unmapped, @value{GDBN} assumes it can find the
|
|
overlay's functions and variables at their load addresses.
|
|
|
|
@item overlay auto
|
|
Enable @dfn{automatic} overlay debugging. In this mode, @value{GDBN}
|
|
consults a data structure the overlay manager maintains in the inferior
|
|
to see which overlays are mapped. For details, see @ref{Automatic
|
|
Overlay Debugging}.
|
|
|
|
@item overlay load-target
|
|
@itemx overlay load
|
|
@cindex reloading the overlay table
|
|
Re-read the overlay table from the inferior. Normally, @value{GDBN}
|
|
re-reads the table @value{GDBN} automatically each time the inferior
|
|
stops, so this command should only be necessary if you have changed the
|
|
overlay mapping yourself using @value{GDBN}. This command is only
|
|
useful when using automatic overlay debugging.
|
|
|
|
@item overlay list-overlays
|
|
@itemx overlay list
|
|
@cindex listing mapped overlays
|
|
Display a list of the overlays currently mapped, along with their mapped
|
|
addresses, load addresses, and sizes.
|
|
|
|
@end table
|
|
|
|
Normally, when @value{GDBN} prints a code address, it includes the name
|
|
of the function the address falls in:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) print main
|
|
$3 = @{int ()@} 0x11a0 <main>
|
|
@end smallexample
|
|
@noindent
|
|
When overlay debugging is enabled, @value{GDBN} recognizes code in
|
|
unmapped overlays, and prints the names of unmapped functions with
|
|
asterisks around them. For example, if @code{foo} is a function in an
|
|
unmapped overlay, @value{GDBN} prints it this way:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) overlay list
|
|
No sections are mapped.
|
|
(@value{GDBP}) print foo
|
|
$5 = @{int (int)@} 0x100000 <*foo*>
|
|
@end smallexample
|
|
@noindent
|
|
When @code{foo}'s overlay is mapped, @value{GDBN} prints the function's
|
|
name normally:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) overlay list
|
|
Section .ov.foo.text, loaded at 0x100000 - 0x100034,
|
|
mapped at 0x1016 - 0x104a
|
|
(@value{GDBP}) print foo
|
|
$6 = @{int (int)@} 0x1016 <foo>
|
|
@end smallexample
|
|
|
|
When overlay debugging is enabled, @value{GDBN} can find the correct
|
|
address for functions and variables in an overlay, whether or not the
|
|
overlay is mapped. This allows most @value{GDBN} commands, like
|
|
@code{break} and @code{disassemble}, to work normally, even on unmapped
|
|
code. However, @value{GDBN}'s breakpoint support has some limitations:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
@cindex breakpoints in overlays
|
|
@cindex overlays, setting breakpoints in
|
|
You can set breakpoints in functions in unmapped overlays, as long as
|
|
@value{GDBN} can write to the overlay at its load address.
|
|
@item
|
|
@value{GDBN} can not set hardware or simulator-based breakpoints in
|
|
unmapped overlays. However, if you set a breakpoint at the end of your
|
|
overlay manager (and tell @value{GDBN} which overlays are now mapped, if
|
|
you are using manual overlay management), @value{GDBN} will re-set its
|
|
breakpoints properly.
|
|
@end itemize
|
|
|
|
|
|
@node Automatic Overlay Debugging
|
|
@section Automatic Overlay Debugging
|
|
@cindex automatic overlay debugging
|
|
|
|
@value{GDBN} can automatically track which overlays are mapped and which
|
|
are not, given some simple co-operation from the overlay manager in the
|
|
inferior. If you enable automatic overlay debugging with the
|
|
@code{overlay auto} command (@pxref{Overlay Commands}), @value{GDBN}
|
|
looks in the inferior's memory for certain variables describing the
|
|
current state of the overlays.
|
|
|
|
Here are the variables your overlay manager must define to support
|
|
@value{GDBN}'s automatic overlay debugging:
|
|
|
|
@table @asis
|
|
|
|
@item @code{_ovly_table}:
|
|
This variable must be an array of the following structures:
|
|
|
|
@smallexample
|
|
struct
|
|
@{
|
|
/* The overlay's mapped address. */
|
|
unsigned long vma;
|
|
|
|
/* The size of the overlay, in bytes. */
|
|
unsigned long size;
|
|
|
|
/* The overlay's load address. */
|
|
unsigned long lma;
|
|
|
|
/* Non-zero if the overlay is currently mapped;
|
|
zero otherwise. */
|
|
unsigned long mapped;
|
|
@}
|
|
@end smallexample
|
|
|
|
@item @code{_novlys}:
|
|
This variable must be a four-byte signed integer, holding the total
|
|
number of elements in @code{_ovly_table}.
|
|
|
|
@end table
|
|
|
|
To decide whether a particular overlay is mapped or not, @value{GDBN}
|
|
looks for an entry in @w{@code{_ovly_table}} whose @code{vma} and
|
|
@code{lma} members equal the VMA and LMA of the overlay's section in the
|
|
executable file. When @value{GDBN} finds a matching entry, it consults
|
|
the entry's @code{mapped} member to determine whether the overlay is
|
|
currently mapped.
|
|
|
|
In addition, your overlay manager may define a function called
|
|
@code{_ovly_debug_event}. If this function is defined, @value{GDBN}
|
|
will silently set a breakpoint there. If the overlay manager then
|
|
calls this function whenever it has changed the overlay table, this
|
|
will enable @value{GDBN} to accurately keep track of which overlays
|
|
are in program memory, and update any breakpoints that may be set
|
|
in overlays. This will allow breakpoints to work even if the
|
|
overlays are kept in ROM or other non-writable memory while they
|
|
are not being executed.
|
|
|
|
@node Overlay Sample Program
|
|
@section Overlay Sample Program
|
|
@cindex overlay example program
|
|
|
|
When linking a program which uses overlays, you must place the overlays
|
|
at their load addresses, while relocating them to run at their mapped
|
|
addresses. To do this, you must write a linker script (@pxref{Overlay
|
|
Description,,, ld.info, Using ld: the GNU linker}). Unfortunately,
|
|
since linker scripts are specific to a particular host system, target
|
|
architecture, and target memory layout, this manual cannot provide
|
|
portable sample code demonstrating @value{GDBN}'s overlay support.
|
|
|
|
However, the @value{GDBN} source distribution does contain an overlaid
|
|
program, with linker scripts for a few systems, as part of its test
|
|
suite. The program consists of the following files from
|
|
@file{gdb/testsuite/gdb.base}:
|
|
|
|
@table @file
|
|
@item overlays.c
|
|
The main program file.
|
|
@item ovlymgr.c
|
|
A simple overlay manager, used by @file{overlays.c}.
|
|
@item foo.c
|
|
@itemx bar.c
|
|
@itemx baz.c
|
|
@itemx grbx.c
|
|
Overlay modules, loaded and used by @file{overlays.c}.
|
|
@item d10v.ld
|
|
@itemx m32r.ld
|
|
Linker scripts for linking the test program on the @code{d10v-elf}
|
|
and @code{m32r-elf} targets.
|
|
@end table
|
|
|
|
You can build the test program using the @code{d10v-elf} GCC
|
|
cross-compiler like this:
|
|
|
|
@smallexample
|
|
$ d10v-elf-gcc -g -c overlays.c
|
|
$ d10v-elf-gcc -g -c ovlymgr.c
|
|
$ d10v-elf-gcc -g -c foo.c
|
|
$ d10v-elf-gcc -g -c bar.c
|
|
$ d10v-elf-gcc -g -c baz.c
|
|
$ d10v-elf-gcc -g -c grbx.c
|
|
$ d10v-elf-gcc -g overlays.o ovlymgr.o foo.o bar.o \
|
|
baz.o grbx.o -Wl,-Td10v.ld -o overlays
|
|
@end smallexample
|
|
|
|
The build process is identical for any other architecture, except that
|
|
you must substitute the appropriate compiler and linker script for the
|
|
target system for @code{d10v-elf-gcc} and @code{d10v.ld}.
|
|
|
|
|
|
@node Languages
|
|
@chapter Using @value{GDBN} with Different Languages
|
|
@cindex languages
|
|
|
|
Although programming languages generally have common aspects, they are
|
|
rarely expressed in the same manner. For instance, in ANSI C,
|
|
dereferencing a pointer @code{p} is accomplished by @code{*p}, but in
|
|
Modula-2, it is accomplished by @code{p^}. Values can also be
|
|
represented (and displayed) differently. Hex numbers in C appear as
|
|
@samp{0x1ae}, while in Modula-2 they appear as @samp{1AEH}.
|
|
|
|
@cindex working language
|
|
Language-specific information is built into @value{GDBN} for some languages,
|
|
allowing you to express operations like the above in your program's
|
|
native language, and allowing @value{GDBN} to output values in a manner
|
|
consistent with the syntax of your program's native language. The
|
|
language you use to build expressions is called the @dfn{working
|
|
language}.
|
|
|
|
@menu
|
|
* Setting:: Switching between source languages
|
|
* Show:: Displaying the language
|
|
* Checks:: Type and range checks
|
|
* Supported Languages:: Supported languages
|
|
* Unsupported Languages:: Unsupported languages
|
|
@end menu
|
|
|
|
@node Setting
|
|
@section Switching Between Source Languages
|
|
|
|
There are two ways to control the working language---either have @value{GDBN}
|
|
set it automatically, or select it manually yourself. You can use the
|
|
@code{set language} command for either purpose. On startup, @value{GDBN}
|
|
defaults to setting the language automatically. The working language is
|
|
used to determine how expressions you type are interpreted, how values
|
|
are printed, etc.
|
|
|
|
In addition to the working language, every source file that
|
|
@value{GDBN} knows about has its own working language. For some object
|
|
file formats, the compiler might indicate which language a particular
|
|
source file is in. However, most of the time @value{GDBN} infers the
|
|
language from the name of the file. The language of a source file
|
|
controls whether C@t{++} names are demangled---this way @code{backtrace} can
|
|
show each frame appropriately for its own language. There is no way to
|
|
set the language of a source file from within @value{GDBN}, but you can
|
|
set the language associated with a filename extension. @xref{Show, ,
|
|
Displaying the Language}.
|
|
|
|
This is most commonly a problem when you use a program, such
|
|
as @code{cfront} or @code{f2c}, that generates C but is written in
|
|
another language. In that case, make the
|
|
program use @code{#line} directives in its C output; that way
|
|
@value{GDBN} will know the correct language of the source code of the original
|
|
program, and will display that source code, not the generated C code.
|
|
|
|
@menu
|
|
* Filenames:: Filename extensions and languages.
|
|
* Manually:: Setting the working language manually
|
|
* Automatically:: Having @value{GDBN} infer the source language
|
|
@end menu
|
|
|
|
@node Filenames
|
|
@subsection List of Filename Extensions and Languages
|
|
|
|
If a source file name ends in one of the following extensions, then
|
|
@value{GDBN} infers that its language is the one indicated.
|
|
|
|
@table @file
|
|
@item .ada
|
|
@itemx .ads
|
|
@itemx .adb
|
|
@itemx .a
|
|
Ada source file.
|
|
|
|
@item .c
|
|
C source file
|
|
|
|
@item .C
|
|
@itemx .cc
|
|
@itemx .cp
|
|
@itemx .cpp
|
|
@itemx .cxx
|
|
@itemx .c++
|
|
C@t{++} source file
|
|
|
|
@item .d
|
|
D source file
|
|
|
|
@item .m
|
|
Objective-C source file
|
|
|
|
@item .f
|
|
@itemx .F
|
|
Fortran source file
|
|
|
|
@item .mod
|
|
Modula-2 source file
|
|
|
|
@item .s
|
|
@itemx .S
|
|
Assembler source file. This actually behaves almost like C, but
|
|
@value{GDBN} does not skip over function prologues when stepping.
|
|
@end table
|
|
|
|
In addition, you may set the language associated with a filename
|
|
extension. @xref{Show, , Displaying the Language}.
|
|
|
|
@node Manually
|
|
@subsection Setting the Working Language
|
|
|
|
If you allow @value{GDBN} to set the language automatically,
|
|
expressions are interpreted the same way in your debugging session and
|
|
your program.
|
|
|
|
@kindex set language
|
|
If you wish, you may set the language manually. To do this, issue the
|
|
command @samp{set language @var{lang}}, where @var{lang} is the name of
|
|
a language, such as
|
|
@code{c} or @code{modula-2}.
|
|
For a list of the supported languages, type @samp{set language}.
|
|
|
|
Setting the language manually prevents @value{GDBN} from updating the working
|
|
language automatically. This can lead to confusion if you try
|
|
to debug a program when the working language is not the same as the
|
|
source language, when an expression is acceptable to both
|
|
languages---but means different things. For instance, if the current
|
|
source file were written in C, and @value{GDBN} was parsing Modula-2, a
|
|
command such as:
|
|
|
|
@smallexample
|
|
print a = b + c
|
|
@end smallexample
|
|
|
|
@noindent
|
|
might not have the effect you intended. In C, this means to add
|
|
@code{b} and @code{c} and place the result in @code{a}. The result
|
|
printed would be the value of @code{a}. In Modula-2, this means to compare
|
|
@code{a} to the result of @code{b+c}, yielding a @code{BOOLEAN} value.
|
|
|
|
@node Automatically
|
|
@subsection Having @value{GDBN} Infer the Source Language
|
|
|
|
To have @value{GDBN} set the working language automatically, use
|
|
@samp{set language local} or @samp{set language auto}. @value{GDBN}
|
|
then infers the working language. That is, when your program stops in a
|
|
frame (usually by encountering a breakpoint), @value{GDBN} sets the
|
|
working language to the language recorded for the function in that
|
|
frame. If the language for a frame is unknown (that is, if the function
|
|
or block corresponding to the frame was defined in a source file that
|
|
does not have a recognized extension), the current working language is
|
|
not changed, and @value{GDBN} issues a warning.
|
|
|
|
This may not seem necessary for most programs, which are written
|
|
entirely in one source language. However, program modules and libraries
|
|
written in one source language can be used by a main program written in
|
|
a different source language. Using @samp{set language auto} in this
|
|
case frees you from having to set the working language manually.
|
|
|
|
@node Show
|
|
@section Displaying the Language
|
|
|
|
The following commands help you find out which language is the
|
|
working language, and also what language source files were written in.
|
|
|
|
@table @code
|
|
@item show language
|
|
@kindex show language
|
|
Display the current working language. This is the
|
|
language you can use with commands such as @code{print} to
|
|
build and compute expressions that may involve variables in your program.
|
|
|
|
@item info frame
|
|
@kindex info frame@r{, show the source language}
|
|
Display the source language for this frame. This language becomes the
|
|
working language if you use an identifier from this frame.
|
|
@xref{Frame Info, ,Information about a Frame}, to identify the other
|
|
information listed here.
|
|
|
|
@item info source
|
|
@kindex info source@r{, show the source language}
|
|
Display the source language of this source file.
|
|
@xref{Symbols, ,Examining the Symbol Table}, to identify the other
|
|
information listed here.
|
|
@end table
|
|
|
|
In unusual circumstances, you may have source files with extensions
|
|
not in the standard list. You can then set the extension associated
|
|
with a language explicitly:
|
|
|
|
@table @code
|
|
@item set extension-language @var{ext} @var{language}
|
|
@kindex set extension-language
|
|
Tell @value{GDBN} that source files with extension @var{ext} are to be
|
|
assumed as written in the source language @var{language}.
|
|
|
|
@item info extensions
|
|
@kindex info extensions
|
|
List all the filename extensions and the associated languages.
|
|
@end table
|
|
|
|
@node Checks
|
|
@section Type and Range Checking
|
|
|
|
@quotation
|
|
@emph{Warning:} In this release, the @value{GDBN} commands for type and range
|
|
checking are included, but they do not yet have any effect. This
|
|
section documents the intended facilities.
|
|
@end quotation
|
|
@c FIXME remove warning when type/range code added
|
|
|
|
Some languages are designed to guard you against making seemingly common
|
|
errors through a series of compile- and run-time checks. These include
|
|
checking the type of arguments to functions and operators, and making
|
|
sure mathematical overflows are caught at run time. Checks such as
|
|
these help to ensure a program's correctness once it has been compiled
|
|
by eliminating type mismatches, and providing active checks for range
|
|
errors when your program is running.
|
|
|
|
@value{GDBN} can check for conditions like the above if you wish.
|
|
Although @value{GDBN} does not check the statements in your program,
|
|
it can check expressions entered directly into @value{GDBN} for
|
|
evaluation via the @code{print} command, for example. As with the
|
|
working language, @value{GDBN} can also decide whether or not to check
|
|
automatically based on your program's source language.
|
|
@xref{Supported Languages, ,Supported Languages}, for the default
|
|
settings of supported languages.
|
|
|
|
@menu
|
|
* Type Checking:: An overview of type checking
|
|
* Range Checking:: An overview of range checking
|
|
@end menu
|
|
|
|
@cindex type checking
|
|
@cindex checks, type
|
|
@node Type Checking
|
|
@subsection An Overview of Type Checking
|
|
|
|
Some languages, such as Modula-2, are strongly typed, meaning that the
|
|
arguments to operators and functions have to be of the correct type,
|
|
otherwise an error occurs. These checks prevent type mismatch
|
|
errors from ever causing any run-time problems. For example,
|
|
|
|
@smallexample
|
|
1 + 2 @result{} 3
|
|
@exdent but
|
|
@error{} 1 + 2.3
|
|
@end smallexample
|
|
|
|
The second example fails because the @code{CARDINAL} 1 is not
|
|
type-compatible with the @code{REAL} 2.3.
|
|
|
|
For the expressions you use in @value{GDBN} commands, you can tell the
|
|
@value{GDBN} type checker to skip checking;
|
|
to treat any mismatches as errors and abandon the expression;
|
|
or to only issue warnings when type mismatches occur,
|
|
but evaluate the expression anyway. When you choose the last of
|
|
these, @value{GDBN} evaluates expressions like the second example above, but
|
|
also issues a warning.
|
|
|
|
Even if you turn type checking off, there may be other reasons
|
|
related to type that prevent @value{GDBN} from evaluating an expression.
|
|
For instance, @value{GDBN} does not know how to add an @code{int} and
|
|
a @code{struct foo}. These particular type errors have nothing to do
|
|
with the language in use, and usually arise from expressions, such as
|
|
the one described above, which make little sense to evaluate anyway.
|
|
|
|
Each language defines to what degree it is strict about type. For
|
|
instance, both Modula-2 and C require the arguments to arithmetical
|
|
operators to be numbers. In C, enumerated types and pointers can be
|
|
represented as numbers, so that they are valid arguments to mathematical
|
|
operators. @xref{Supported Languages, ,Supported Languages}, for further
|
|
details on specific languages.
|
|
|
|
@value{GDBN} provides some additional commands for controlling the type checker:
|
|
|
|
@kindex set check type
|
|
@kindex show check type
|
|
@table @code
|
|
@item set check type auto
|
|
Set type checking on or off based on the current working language.
|
|
@xref{Supported Languages, ,Supported Languages}, for the default settings for
|
|
each language.
|
|
|
|
@item set check type on
|
|
@itemx set check type off
|
|
Set type checking on or off, overriding the default setting for the
|
|
current working language. Issue a warning if the setting does not
|
|
match the language default. If any type mismatches occur in
|
|
evaluating an expression while type checking is on, @value{GDBN} prints a
|
|
message and aborts evaluation of the expression.
|
|
|
|
@item set check type warn
|
|
Cause the type checker to issue warnings, but to always attempt to
|
|
evaluate the expression. Evaluating the expression may still
|
|
be impossible for other reasons. For example, @value{GDBN} cannot add
|
|
numbers and structures.
|
|
|
|
@item show type
|
|
Show the current setting of the type checker, and whether or not @value{GDBN}
|
|
is setting it automatically.
|
|
@end table
|
|
|
|
@cindex range checking
|
|
@cindex checks, range
|
|
@node Range Checking
|
|
@subsection An Overview of Range Checking
|
|
|
|
In some languages (such as Modula-2), it is an error to exceed the
|
|
bounds of a type; this is enforced with run-time checks. Such range
|
|
checking is meant to ensure program correctness by making sure
|
|
computations do not overflow, or indices on an array element access do
|
|
not exceed the bounds of the array.
|
|
|
|
For expressions you use in @value{GDBN} commands, you can tell
|
|
@value{GDBN} to treat range errors in one of three ways: ignore them,
|
|
always treat them as errors and abandon the expression, or issue
|
|
warnings but evaluate the expression anyway.
|
|
|
|
A range error can result from numerical overflow, from exceeding an
|
|
array index bound, or when you type a constant that is not a member
|
|
of any type. Some languages, however, do not treat overflows as an
|
|
error. In many implementations of C, mathematical overflow causes the
|
|
result to ``wrap around'' to lower values---for example, if @var{m} is
|
|
the largest integer value, and @var{s} is the smallest, then
|
|
|
|
@smallexample
|
|
@var{m} + 1 @result{} @var{s}
|
|
@end smallexample
|
|
|
|
This, too, is specific to individual languages, and in some cases
|
|
specific to individual compilers or machines. @xref{Supported Languages, ,
|
|
Supported Languages}, for further details on specific languages.
|
|
|
|
@value{GDBN} provides some additional commands for controlling the range checker:
|
|
|
|
@kindex set check range
|
|
@kindex show check range
|
|
@table @code
|
|
@item set check range auto
|
|
Set range checking on or off based on the current working language.
|
|
@xref{Supported Languages, ,Supported Languages}, for the default settings for
|
|
each language.
|
|
|
|
@item set check range on
|
|
@itemx set check range off
|
|
Set range checking on or off, overriding the default setting for the
|
|
current working language. A warning is issued if the setting does not
|
|
match the language default. If a range error occurs and range checking is on,
|
|
then a message is printed and evaluation of the expression is aborted.
|
|
|
|
@item set check range warn
|
|
Output messages when the @value{GDBN} range checker detects a range error,
|
|
but attempt to evaluate the expression anyway. Evaluating the
|
|
expression may still be impossible for other reasons, such as accessing
|
|
memory that the process does not own (a typical example from many Unix
|
|
systems).
|
|
|
|
@item show range
|
|
Show the current setting of the range checker, and whether or not it is
|
|
being set automatically by @value{GDBN}.
|
|
@end table
|
|
|
|
@node Supported Languages
|
|
@section Supported Languages
|
|
|
|
@value{GDBN} supports C, C@t{++}, D, Go, Objective-C, Fortran, Java,
|
|
OpenCL C, Pascal, assembly, Modula-2, and Ada.
|
|
@c This is false ...
|
|
Some @value{GDBN} features may be used in expressions regardless of the
|
|
language you use: the @value{GDBN} @code{@@} and @code{::} operators,
|
|
and the @samp{@{type@}addr} construct (@pxref{Expressions,
|
|
,Expressions}) can be used with the constructs of any supported
|
|
language.
|
|
|
|
The following sections detail to what degree each source language is
|
|
supported by @value{GDBN}. These sections are not meant to be language
|
|
tutorials or references, but serve only as a reference guide to what the
|
|
@value{GDBN} expression parser accepts, and what input and output
|
|
formats should look like for different languages. There are many good
|
|
books written on each of these languages; please look to these for a
|
|
language reference or tutorial.
|
|
|
|
@menu
|
|
* C:: C and C@t{++}
|
|
* D:: D
|
|
* Go:: Go
|
|
* Objective-C:: Objective-C
|
|
* OpenCL C:: OpenCL C
|
|
* Fortran:: Fortran
|
|
* Pascal:: Pascal
|
|
* Modula-2:: Modula-2
|
|
* Ada:: Ada
|
|
@end menu
|
|
|
|
@node C
|
|
@subsection C and C@t{++}
|
|
|
|
@cindex C and C@t{++}
|
|
@cindex expressions in C or C@t{++}
|
|
|
|
Since C and C@t{++} are so closely related, many features of @value{GDBN} apply
|
|
to both languages. Whenever this is the case, we discuss those languages
|
|
together.
|
|
|
|
@cindex C@t{++}
|
|
@cindex @code{g++}, @sc{gnu} C@t{++} compiler
|
|
@cindex @sc{gnu} C@t{++}
|
|
The C@t{++} debugging facilities are jointly implemented by the C@t{++}
|
|
compiler and @value{GDBN}. Therefore, to debug your C@t{++} code
|
|
effectively, you must compile your C@t{++} programs with a supported
|
|
C@t{++} compiler, such as @sc{gnu} @code{g++}, or the HP ANSI C@t{++}
|
|
compiler (@code{aCC}).
|
|
|
|
@menu
|
|
* C Operators:: C and C@t{++} operators
|
|
* C Constants:: C and C@t{++} constants
|
|
* C Plus Plus Expressions:: C@t{++} expressions
|
|
* C Defaults:: Default settings for C and C@t{++}
|
|
* C Checks:: C and C@t{++} type and range checks
|
|
* Debugging C:: @value{GDBN} and C
|
|
* Debugging C Plus Plus:: @value{GDBN} features for C@t{++}
|
|
* Decimal Floating Point:: Numbers in Decimal Floating Point format
|
|
@end menu
|
|
|
|
@node C Operators
|
|
@subsubsection C and C@t{++} Operators
|
|
|
|
@cindex C and C@t{++} operators
|
|
|
|
Operators must be defined on values of specific types. For instance,
|
|
@code{+} is defined on numbers, but not on structures. Operators are
|
|
often defined on groups of types.
|
|
|
|
For the purposes of C and C@t{++}, the following definitions hold:
|
|
|
|
@itemize @bullet
|
|
|
|
@item
|
|
@emph{Integral types} include @code{int} with any of its storage-class
|
|
specifiers; @code{char}; @code{enum}; and, for C@t{++}, @code{bool}.
|
|
|
|
@item
|
|
@emph{Floating-point types} include @code{float}, @code{double}, and
|
|
@code{long double} (if supported by the target platform).
|
|
|
|
@item
|
|
@emph{Pointer types} include all types defined as @code{(@var{type} *)}.
|
|
|
|
@item
|
|
@emph{Scalar types} include all of the above.
|
|
|
|
@end itemize
|
|
|
|
@noindent
|
|
The following operators are supported. They are listed here
|
|
in order of increasing precedence:
|
|
|
|
@table @code
|
|
@item ,
|
|
The comma or sequencing operator. Expressions in a comma-separated list
|
|
are evaluated from left to right, with the result of the entire
|
|
expression being the last expression evaluated.
|
|
|
|
@item =
|
|
Assignment. The value of an assignment expression is the value
|
|
assigned. Defined on scalar types.
|
|
|
|
@item @var{op}=
|
|
Used in an expression of the form @w{@code{@var{a} @var{op}= @var{b}}},
|
|
and translated to @w{@code{@var{a} = @var{a op b}}}.
|
|
@w{@code{@var{op}=}} and @code{=} have the same precedence.
|
|
@var{op} is any one of the operators @code{|}, @code{^}, @code{&},
|
|
@code{<<}, @code{>>}, @code{+}, @code{-}, @code{*}, @code{/}, @code{%}.
|
|
|
|
@item ?:
|
|
The ternary operator. @code{@var{a} ? @var{b} : @var{c}} can be thought
|
|
of as: if @var{a} then @var{b} else @var{c}. @var{a} should be of an
|
|
integral type.
|
|
|
|
@item ||
|
|
Logical @sc{or}. Defined on integral types.
|
|
|
|
@item &&
|
|
Logical @sc{and}. Defined on integral types.
|
|
|
|
@item |
|
|
Bitwise @sc{or}. Defined on integral types.
|
|
|
|
@item ^
|
|
Bitwise exclusive-@sc{or}. Defined on integral types.
|
|
|
|
@item &
|
|
Bitwise @sc{and}. Defined on integral types.
|
|
|
|
@item ==@r{, }!=
|
|
Equality and inequality. Defined on scalar types. The value of these
|
|
expressions is 0 for false and non-zero for true.
|
|
|
|
@item <@r{, }>@r{, }<=@r{, }>=
|
|
Less than, greater than, less than or equal, greater than or equal.
|
|
Defined on scalar types. The value of these expressions is 0 for false
|
|
and non-zero for true.
|
|
|
|
@item <<@r{, }>>
|
|
left shift, and right shift. Defined on integral types.
|
|
|
|
@item @@
|
|
The @value{GDBN} ``artificial array'' operator (@pxref{Expressions, ,Expressions}).
|
|
|
|
@item +@r{, }-
|
|
Addition and subtraction. Defined on integral types, floating-point types and
|
|
pointer types.
|
|
|
|
@item *@r{, }/@r{, }%
|
|
Multiplication, division, and modulus. Multiplication and division are
|
|
defined on integral and floating-point types. Modulus is defined on
|
|
integral types.
|
|
|
|
@item ++@r{, }--
|
|
Increment and decrement. When appearing before a variable, the
|
|
operation is performed before the variable is used in an expression;
|
|
when appearing after it, the variable's value is used before the
|
|
operation takes place.
|
|
|
|
@item *
|
|
Pointer dereferencing. Defined on pointer types. Same precedence as
|
|
@code{++}.
|
|
|
|
@item &
|
|
Address operator. Defined on variables. Same precedence as @code{++}.
|
|
|
|
For debugging C@t{++}, @value{GDBN} implements a use of @samp{&} beyond what is
|
|
allowed in the C@t{++} language itself: you can use @samp{&(&@var{ref})}
|
|
to examine the address
|
|
where a C@t{++} reference variable (declared with @samp{&@var{ref}}) is
|
|
stored.
|
|
|
|
@item -
|
|
Negative. Defined on integral and floating-point types. Same
|
|
precedence as @code{++}.
|
|
|
|
@item !
|
|
Logical negation. Defined on integral types. Same precedence as
|
|
@code{++}.
|
|
|
|
@item ~
|
|
Bitwise complement operator. Defined on integral types. Same precedence as
|
|
@code{++}.
|
|
|
|
|
|
@item .@r{, }->
|
|
Structure member, and pointer-to-structure member. For convenience,
|
|
@value{GDBN} regards the two as equivalent, choosing whether to dereference a
|
|
pointer based on the stored type information.
|
|
Defined on @code{struct} and @code{union} data.
|
|
|
|
@item .*@r{, }->*
|
|
Dereferences of pointers to members.
|
|
|
|
@item []
|
|
Array indexing. @code{@var{a}[@var{i}]} is defined as
|
|
@code{*(@var{a}+@var{i})}. Same precedence as @code{->}.
|
|
|
|
@item ()
|
|
Function parameter list. Same precedence as @code{->}.
|
|
|
|
@item ::
|
|
C@t{++} scope resolution operator. Defined on @code{struct}, @code{union},
|
|
and @code{class} types.
|
|
|
|
@item ::
|
|
Doubled colons also represent the @value{GDBN} scope operator
|
|
(@pxref{Expressions, ,Expressions}). Same precedence as @code{::},
|
|
above.
|
|
@end table
|
|
|
|
If an operator is redefined in the user code, @value{GDBN} usually
|
|
attempts to invoke the redefined version instead of using the operator's
|
|
predefined meaning.
|
|
|
|
@node C Constants
|
|
@subsubsection C and C@t{++} Constants
|
|
|
|
@cindex C and C@t{++} constants
|
|
|
|
@value{GDBN} allows you to express the constants of C and C@t{++} in the
|
|
following ways:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
Integer constants are a sequence of digits. Octal constants are
|
|
specified by a leading @samp{0} (i.e.@: zero), and hexadecimal constants
|
|
by a leading @samp{0x} or @samp{0X}. Constants may also end with a letter
|
|
@samp{l}, specifying that the constant should be treated as a
|
|
@code{long} value.
|
|
|
|
@item
|
|
Floating point constants are a sequence of digits, followed by a decimal
|
|
point, followed by a sequence of digits, and optionally followed by an
|
|
exponent. An exponent is of the form:
|
|
@samp{@w{e@r{[[}+@r{]|}-@r{]}@var{nnn}}}, where @var{nnn} is another
|
|
sequence of digits. The @samp{+} is optional for positive exponents.
|
|
A floating-point constant may also end with a letter @samp{f} or
|
|
@samp{F}, specifying that the constant should be treated as being of
|
|
the @code{float} (as opposed to the default @code{double}) type; or with
|
|
a letter @samp{l} or @samp{L}, which specifies a @code{long double}
|
|
constant.
|
|
|
|
@item
|
|
Enumerated constants consist of enumerated identifiers, or their
|
|
integral equivalents.
|
|
|
|
@item
|
|
Character constants are a single character surrounded by single quotes
|
|
(@code{'}), or a number---the ordinal value of the corresponding character
|
|
(usually its @sc{ascii} value). Within quotes, the single character may
|
|
be represented by a letter or by @dfn{escape sequences}, which are of
|
|
the form @samp{\@var{nnn}}, where @var{nnn} is the octal representation
|
|
of the character's ordinal value; or of the form @samp{\@var{x}}, where
|
|
@samp{@var{x}} is a predefined special character---for example,
|
|
@samp{\n} for newline.
|
|
|
|
Wide character constants can be written by prefixing a character
|
|
constant with @samp{L}, as in C. For example, @samp{L'x'} is the wide
|
|
form of @samp{x}. The target wide character set is used when
|
|
computing the value of this constant (@pxref{Character Sets}).
|
|
|
|
@item
|
|
String constants are a sequence of character constants surrounded by
|
|
double quotes (@code{"}). Any valid character constant (as described
|
|
above) may appear. Double quotes within the string must be preceded by
|
|
a backslash, so for instance @samp{"a\"b'c"} is a string of five
|
|
characters.
|
|
|
|
Wide string constants can be written by prefixing a string constant
|
|
with @samp{L}, as in C. The target wide character set is used when
|
|
computing the value of this constant (@pxref{Character Sets}).
|
|
|
|
@item
|
|
Pointer constants are an integral value. You can also write pointers
|
|
to constants using the C operator @samp{&}.
|
|
|
|
@item
|
|
Array constants are comma-separated lists surrounded by braces @samp{@{}
|
|
and @samp{@}}; for example, @samp{@{1,2,3@}} is a three-element array of
|
|
integers, @samp{@{@{1,2@}, @{3,4@}, @{5,6@}@}} is a three-by-two array,
|
|
and @samp{@{&"hi", &"there", &"fred"@}} is a three-element array of pointers.
|
|
@end itemize
|
|
|
|
@node C Plus Plus Expressions
|
|
@subsubsection C@t{++} Expressions
|
|
|
|
@cindex expressions in C@t{++}
|
|
@value{GDBN} expression handling can interpret most C@t{++} expressions.
|
|
|
|
@cindex debugging C@t{++} programs
|
|
@cindex C@t{++} compilers
|
|
@cindex debug formats and C@t{++}
|
|
@cindex @value{NGCC} and C@t{++}
|
|
@quotation
|
|
@emph{Warning:} @value{GDBN} can only debug C@t{++} code if you use
|
|
the proper compiler and the proper debug format. Currently,
|
|
@value{GDBN} works best when debugging C@t{++} code that is compiled
|
|
with the most recent version of @value{NGCC} possible. The DWARF
|
|
debugging format is preferred; @value{NGCC} defaults to this on most
|
|
popular platforms. Other compilers and/or debug formats are likely to
|
|
work badly or not at all when using @value{GDBN} to debug C@t{++}
|
|
code. @xref{Compilation}.
|
|
@end quotation
|
|
|
|
@enumerate
|
|
|
|
@cindex member functions
|
|
@item
|
|
Member function calls are allowed; you can use expressions like
|
|
|
|
@smallexample
|
|
count = aml->GetOriginal(x, y)
|
|
@end smallexample
|
|
|
|
@vindex this@r{, inside C@t{++} member functions}
|
|
@cindex namespace in C@t{++}
|
|
@item
|
|
While a member function is active (in the selected stack frame), your
|
|
expressions have the same namespace available as the member function;
|
|
that is, @value{GDBN} allows implicit references to the class instance
|
|
pointer @code{this} following the same rules as C@t{++}. @code{using}
|
|
declarations in the current scope are also respected by @value{GDBN}.
|
|
|
|
@cindex call overloaded functions
|
|
@cindex overloaded functions, calling
|
|
@cindex type conversions in C@t{++}
|
|
@item
|
|
You can call overloaded functions; @value{GDBN} resolves the function
|
|
call to the right definition, with some restrictions. @value{GDBN} does not
|
|
perform overload resolution involving user-defined type conversions,
|
|
calls to constructors, or instantiations of templates that do not exist
|
|
in the program. It also cannot handle ellipsis argument lists or
|
|
default arguments.
|
|
|
|
It does perform integral conversions and promotions, floating-point
|
|
promotions, arithmetic conversions, pointer conversions, conversions of
|
|
class objects to base classes, and standard conversions such as those of
|
|
functions or arrays to pointers; it requires an exact match on the
|
|
number of function arguments.
|
|
|
|
Overload resolution is always performed, unless you have specified
|
|
@code{set overload-resolution off}. @xref{Debugging C Plus Plus,
|
|
,@value{GDBN} Features for C@t{++}}.
|
|
|
|
You must specify @code{set overload-resolution off} in order to use an
|
|
explicit function signature to call an overloaded function, as in
|
|
@smallexample
|
|
p 'foo(char,int)'('x', 13)
|
|
@end smallexample
|
|
|
|
The @value{GDBN} command-completion facility can simplify this;
|
|
see @ref{Completion, ,Command Completion}.
|
|
|
|
@cindex reference declarations
|
|
@item
|
|
@value{GDBN} understands variables declared as C@t{++} references; you can use
|
|
them in expressions just as you do in C@t{++} source---they are automatically
|
|
dereferenced.
|
|
|
|
In the parameter list shown when @value{GDBN} displays a frame, the values of
|
|
reference variables are not displayed (unlike other variables); this
|
|
avoids clutter, since references are often used for large structures.
|
|
The @emph{address} of a reference variable is always shown, unless
|
|
you have specified @samp{set print address off}.
|
|
|
|
@item
|
|
@value{GDBN} supports the C@t{++} name resolution operator @code{::}---your
|
|
expressions can use it just as expressions in your program do. Since
|
|
one scope may be defined in another, you can use @code{::} repeatedly if
|
|
necessary, for example in an expression like
|
|
@samp{@var{scope1}::@var{scope2}::@var{name}}. @value{GDBN} also allows
|
|
resolving name scope by reference to source files, in both C and C@t{++}
|
|
debugging (@pxref{Variables, ,Program Variables}).
|
|
|
|
@item
|
|
@value{GDBN} performs argument-dependent lookup, following the C@t{++}
|
|
specification.
|
|
@end enumerate
|
|
|
|
@node C Defaults
|
|
@subsubsection C and C@t{++} Defaults
|
|
|
|
@cindex C and C@t{++} defaults
|
|
|
|
If you allow @value{GDBN} to set type and range checking automatically, they
|
|
both default to @code{off} whenever the working language changes to
|
|
C or C@t{++}. This happens regardless of whether you or @value{GDBN}
|
|
selects the working language.
|
|
|
|
If you allow @value{GDBN} to set the language automatically, it
|
|
recognizes source files whose names end with @file{.c}, @file{.C}, or
|
|
@file{.cc}, etc, and when @value{GDBN} enters code compiled from one of
|
|
these files, it sets the working language to C or C@t{++}.
|
|
@xref{Automatically, ,Having @value{GDBN} Infer the Source Language},
|
|
for further details.
|
|
|
|
@c Type checking is (a) primarily motivated by Modula-2, and (b)
|
|
@c unimplemented. If (b) changes, it might make sense to let this node
|
|
@c appear even if Mod-2 does not, but meanwhile ignore it. roland 16jul93.
|
|
|
|
@node C Checks
|
|
@subsubsection C and C@t{++} Type and Range Checks
|
|
|
|
@cindex C and C@t{++} checks
|
|
|
|
By default, when @value{GDBN} parses C or C@t{++} expressions, type checking
|
|
is not used. However, if you turn type checking on, @value{GDBN}
|
|
considers two variables type equivalent if:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
The two variables are structured and have the same structure, union, or
|
|
enumerated tag.
|
|
|
|
@item
|
|
The two variables have the same type name, or types that have been
|
|
declared equivalent through @code{typedef}.
|
|
|
|
@ignore
|
|
@c leaving this out because neither J Gilmore nor R Pesch understand it.
|
|
@c FIXME--beers?
|
|
@item
|
|
The two @code{struct}, @code{union}, or @code{enum} variables are
|
|
declared in the same declaration. (Note: this may not be true for all C
|
|
compilers.)
|
|
@end ignore
|
|
@end itemize
|
|
|
|
Range checking, if turned on, is done on mathematical operations. Array
|
|
indices are not checked, since they are often used to index a pointer
|
|
that is not itself an array.
|
|
|
|
@node Debugging C
|
|
@subsubsection @value{GDBN} and C
|
|
|
|
The @code{set print union} and @code{show print union} commands apply to
|
|
the @code{union} type. When set to @samp{on}, any @code{union} that is
|
|
inside a @code{struct} or @code{class} is also printed. Otherwise, it
|
|
appears as @samp{@{...@}}.
|
|
|
|
The @code{@@} operator aids in the debugging of dynamic arrays, formed
|
|
with pointers and a memory allocation function. @xref{Expressions,
|
|
,Expressions}.
|
|
|
|
@node Debugging C Plus Plus
|
|
@subsubsection @value{GDBN} Features for C@t{++}
|
|
|
|
@cindex commands for C@t{++}
|
|
|
|
Some @value{GDBN} commands are particularly useful with C@t{++}, and some are
|
|
designed specifically for use with C@t{++}. Here is a summary:
|
|
|
|
@table @code
|
|
@cindex break in overloaded functions
|
|
@item @r{breakpoint menus}
|
|
When you want a breakpoint in a function whose name is overloaded,
|
|
@value{GDBN} has the capability to display a menu of possible breakpoint
|
|
locations to help you specify which function definition you want.
|
|
@xref{Ambiguous Expressions,,Ambiguous Expressions}.
|
|
|
|
@cindex overloading in C@t{++}
|
|
@item rbreak @var{regex}
|
|
Setting breakpoints using regular expressions is helpful for setting
|
|
breakpoints on overloaded functions that are not members of any special
|
|
classes.
|
|
@xref{Set Breaks, ,Setting Breakpoints}.
|
|
|
|
@cindex C@t{++} exception handling
|
|
@item catch throw
|
|
@itemx catch catch
|
|
Debug C@t{++} exception handling using these commands. @xref{Set
|
|
Catchpoints, , Setting Catchpoints}.
|
|
|
|
@cindex inheritance
|
|
@item ptype @var{typename}
|
|
Print inheritance relationships as well as other information for type
|
|
@var{typename}.
|
|
@xref{Symbols, ,Examining the Symbol Table}.
|
|
|
|
@item info vtbl @var{expression}.
|
|
The @code{info vtbl} command can be used to display the virtual
|
|
method tables of the object computed by @var{expression}. This shows
|
|
one entry per virtual table; there may be multiple virtual tables when
|
|
multiple inheritance is in use.
|
|
|
|
@cindex C@t{++} symbol display
|
|
@item set print demangle
|
|
@itemx show print demangle
|
|
@itemx set print asm-demangle
|
|
@itemx show print asm-demangle
|
|
Control whether C@t{++} symbols display in their source form, both when
|
|
displaying code as C@t{++} source and when displaying disassemblies.
|
|
@xref{Print Settings, ,Print Settings}.
|
|
|
|
@item set print object
|
|
@itemx show print object
|
|
Choose whether to print derived (actual) or declared types of objects.
|
|
@xref{Print Settings, ,Print Settings}.
|
|
|
|
@item set print vtbl
|
|
@itemx show print vtbl
|
|
Control the format for printing virtual function tables.
|
|
@xref{Print Settings, ,Print Settings}.
|
|
(The @code{vtbl} commands do not work on programs compiled with the HP
|
|
ANSI C@t{++} compiler (@code{aCC}).)
|
|
|
|
@kindex set overload-resolution
|
|
@cindex overloaded functions, overload resolution
|
|
@item set overload-resolution on
|
|
Enable overload resolution for C@t{++} expression evaluation. The default
|
|
is on. For overloaded functions, @value{GDBN} evaluates the arguments
|
|
and searches for a function whose signature matches the argument types,
|
|
using the standard C@t{++} conversion rules (see @ref{C Plus Plus
|
|
Expressions, ,C@t{++} Expressions}, for details).
|
|
If it cannot find a match, it emits a message.
|
|
|
|
@item set overload-resolution off
|
|
Disable overload resolution for C@t{++} expression evaluation. For
|
|
overloaded functions that are not class member functions, @value{GDBN}
|
|
chooses the first function of the specified name that it finds in the
|
|
symbol table, whether or not its arguments are of the correct type. For
|
|
overloaded functions that are class member functions, @value{GDBN}
|
|
searches for a function whose signature @emph{exactly} matches the
|
|
argument types.
|
|
|
|
@kindex show overload-resolution
|
|
@item show overload-resolution
|
|
Show the current setting of overload resolution.
|
|
|
|
@item @r{Overloaded symbol names}
|
|
You can specify a particular definition of an overloaded symbol, using
|
|
the same notation that is used to declare such symbols in C@t{++}: type
|
|
@code{@var{symbol}(@var{types})} rather than just @var{symbol}. You can
|
|
also use the @value{GDBN} command-line word completion facilities to list the
|
|
available choices, or to finish the type list for you.
|
|
@xref{Completion,, Command Completion}, for details on how to do this.
|
|
@end table
|
|
|
|
@node Decimal Floating Point
|
|
@subsubsection Decimal Floating Point format
|
|
@cindex decimal floating point format
|
|
|
|
@value{GDBN} can examine, set and perform computations with numbers in
|
|
decimal floating point format, which in the C language correspond to the
|
|
@code{_Decimal32}, @code{_Decimal64} and @code{_Decimal128} types as
|
|
specified by the extension to support decimal floating-point arithmetic.
|
|
|
|
There are two encodings in use, depending on the architecture: BID (Binary
|
|
Integer Decimal) for x86 and x86-64, and DPD (Densely Packed Decimal) for
|
|
PowerPC. @value{GDBN} will use the appropriate encoding for the configured
|
|
target.
|
|
|
|
Because of a limitation in @file{libdecnumber}, the library used by @value{GDBN}
|
|
to manipulate decimal floating point numbers, it is not possible to convert
|
|
(using a cast, for example) integers wider than 32-bit to decimal float.
|
|
|
|
In addition, in order to imitate @value{GDBN}'s behaviour with binary floating
|
|
point computations, error checking in decimal float operations ignores
|
|
underflow, overflow and divide by zero exceptions.
|
|
|
|
In the PowerPC architecture, @value{GDBN} provides a set of pseudo-registers
|
|
to inspect @code{_Decimal128} values stored in floating point registers.
|
|
See @ref{PowerPC,,PowerPC} for more details.
|
|
|
|
@node D
|
|
@subsection D
|
|
|
|
@cindex D
|
|
@value{GDBN} can be used to debug programs written in D and compiled with
|
|
GDC, LDC or DMD compilers. Currently @value{GDBN} supports only one D
|
|
specific feature --- dynamic arrays.
|
|
|
|
@node Go
|
|
@subsection Go
|
|
|
|
@cindex Go (programming language)
|
|
@value{GDBN} can be used to debug programs written in Go and compiled with
|
|
@file{gccgo} or @file{6g} compilers.
|
|
|
|
Here is a summary of the Go-specific features and restrictions:
|
|
|
|
@table @code
|
|
@cindex current Go package
|
|
@item The current Go package
|
|
The name of the current package does not need to be specified when
|
|
specifying global variables and functions.
|
|
|
|
For example, given the program:
|
|
|
|
@example
|
|
package main
|
|
var myglob = "Shall we?"
|
|
func main () @{
|
|
// ...
|
|
@}
|
|
@end example
|
|
|
|
When stopped inside @code{main} either of these work:
|
|
|
|
@example
|
|
(gdb) p myglob
|
|
(gdb) p main.myglob
|
|
@end example
|
|
|
|
@cindex builtin Go types
|
|
@item Builtin Go types
|
|
The @code{string} type is recognized by @value{GDBN} and is printed
|
|
as a string.
|
|
|
|
@cindex builtin Go functions
|
|
@item Builtin Go functions
|
|
The @value{GDBN} expression parser recognizes the @code{unsafe.Sizeof}
|
|
function and handles it internally.
|
|
|
|
@cindex restrictions on Go expressions
|
|
@item Restrictions on Go expressions
|
|
All Go operators are supported except @code{&^}.
|
|
The Go @code{_} ``blank identifier'' is not supported.
|
|
Automatic dereferencing of pointers is not supported.
|
|
@end table
|
|
|
|
@node Objective-C
|
|
@subsection Objective-C
|
|
|
|
@cindex Objective-C
|
|
This section provides information about some commands and command
|
|
options that are useful for debugging Objective-C code. See also
|
|
@ref{Symbols, info classes}, and @ref{Symbols, info selectors}, for a
|
|
few more commands specific to Objective-C support.
|
|
|
|
@menu
|
|
* Method Names in Commands::
|
|
* The Print Command with Objective-C::
|
|
@end menu
|
|
|
|
@node Method Names in Commands
|
|
@subsubsection Method Names in Commands
|
|
|
|
The following commands have been extended to accept Objective-C method
|
|
names as line specifications:
|
|
|
|
@kindex clear@r{, and Objective-C}
|
|
@kindex break@r{, and Objective-C}
|
|
@kindex info line@r{, and Objective-C}
|
|
@kindex jump@r{, and Objective-C}
|
|
@kindex list@r{, and Objective-C}
|
|
@itemize
|
|
@item @code{clear}
|
|
@item @code{break}
|
|
@item @code{info line}
|
|
@item @code{jump}
|
|
@item @code{list}
|
|
@end itemize
|
|
|
|
A fully qualified Objective-C method name is specified as
|
|
|
|
@smallexample
|
|
-[@var{Class} @var{methodName}]
|
|
@end smallexample
|
|
|
|
where the minus sign is used to indicate an instance method and a
|
|
plus sign (not shown) is used to indicate a class method. The class
|
|
name @var{Class} and method name @var{methodName} are enclosed in
|
|
brackets, similar to the way messages are specified in Objective-C
|
|
source code. For example, to set a breakpoint at the @code{create}
|
|
instance method of class @code{Fruit} in the program currently being
|
|
debugged, enter:
|
|
|
|
@smallexample
|
|
break -[Fruit create]
|
|
@end smallexample
|
|
|
|
To list ten program lines around the @code{initialize} class method,
|
|
enter:
|
|
|
|
@smallexample
|
|
list +[NSText initialize]
|
|
@end smallexample
|
|
|
|
In the current version of @value{GDBN}, the plus or minus sign is
|
|
required. In future versions of @value{GDBN}, the plus or minus
|
|
sign will be optional, but you can use it to narrow the search. It
|
|
is also possible to specify just a method name:
|
|
|
|
@smallexample
|
|
break create
|
|
@end smallexample
|
|
|
|
You must specify the complete method name, including any colons. If
|
|
your program's source files contain more than one @code{create} method,
|
|
you'll be presented with a numbered list of classes that implement that
|
|
method. Indicate your choice by number, or type @samp{0} to exit if
|
|
none apply.
|
|
|
|
As another example, to clear a breakpoint established at the
|
|
@code{makeKeyAndOrderFront:} method of the @code{NSWindow} class, enter:
|
|
|
|
@smallexample
|
|
clear -[NSWindow makeKeyAndOrderFront:]
|
|
@end smallexample
|
|
|
|
@node The Print Command with Objective-C
|
|
@subsubsection The Print Command With Objective-C
|
|
@cindex Objective-C, print objects
|
|
@kindex print-object
|
|
@kindex po @r{(@code{print-object})}
|
|
|
|
The print command has also been extended to accept methods. For example:
|
|
|
|
@smallexample
|
|
print -[@var{object} hash]
|
|
@end smallexample
|
|
|
|
@cindex print an Objective-C object description
|
|
@cindex @code{_NSPrintForDebugger}, and printing Objective-C objects
|
|
@noindent
|
|
will tell @value{GDBN} to send the @code{hash} message to @var{object}
|
|
and print the result. Also, an additional command has been added,
|
|
@code{print-object} or @code{po} for short, which is meant to print
|
|
the description of an object. However, this command may only work
|
|
with certain Objective-C libraries that have a particular hook
|
|
function, @code{_NSPrintForDebugger}, defined.
|
|
|
|
@node OpenCL C
|
|
@subsection OpenCL C
|
|
|
|
@cindex OpenCL C
|
|
This section provides information about @value{GDBN}s OpenCL C support.
|
|
|
|
@menu
|
|
* OpenCL C Datatypes::
|
|
* OpenCL C Expressions::
|
|
* OpenCL C Operators::
|
|
@end menu
|
|
|
|
@node OpenCL C Datatypes
|
|
@subsubsection OpenCL C Datatypes
|
|
|
|
@cindex OpenCL C Datatypes
|
|
@value{GDBN} supports the builtin scalar and vector datatypes specified
|
|
by OpenCL 1.1. In addition the half- and double-precision floating point
|
|
data types of the @code{cl_khr_fp16} and @code{cl_khr_fp64} OpenCL
|
|
extensions are also known to @value{GDBN}.
|
|
|
|
@node OpenCL C Expressions
|
|
@subsubsection OpenCL C Expressions
|
|
|
|
@cindex OpenCL C Expressions
|
|
@value{GDBN} supports accesses to vector components including the access as
|
|
lvalue where possible. Since OpenCL C is based on C99 most C expressions
|
|
supported by @value{GDBN} can be used as well.
|
|
|
|
@node OpenCL C Operators
|
|
@subsubsection OpenCL C Operators
|
|
|
|
@cindex OpenCL C Operators
|
|
@value{GDBN} supports the operators specified by OpenCL 1.1 for scalar and
|
|
vector data types.
|
|
|
|
@node Fortran
|
|
@subsection Fortran
|
|
@cindex Fortran-specific support in @value{GDBN}
|
|
|
|
@value{GDBN} can be used to debug programs written in Fortran, but it
|
|
currently supports only the features of Fortran 77 language.
|
|
|
|
@cindex trailing underscore, in Fortran symbols
|
|
Some Fortran compilers (@sc{gnu} Fortran 77 and Fortran 95 compilers
|
|
among them) append an underscore to the names of variables and
|
|
functions. When you debug programs compiled by those compilers, you
|
|
will need to refer to variables and functions with a trailing
|
|
underscore.
|
|
|
|
@menu
|
|
* Fortran Operators:: Fortran operators and expressions
|
|
* Fortran Defaults:: Default settings for Fortran
|
|
* Special Fortran Commands:: Special @value{GDBN} commands for Fortran
|
|
@end menu
|
|
|
|
@node Fortran Operators
|
|
@subsubsection Fortran Operators and Expressions
|
|
|
|
@cindex Fortran operators and expressions
|
|
|
|
Operators must be defined on values of specific types. For instance,
|
|
@code{+} is defined on numbers, but not on characters or other non-
|
|
arithmetic types. Operators are often defined on groups of types.
|
|
|
|
@table @code
|
|
@item **
|
|
The exponentiation operator. It raises the first operand to the power
|
|
of the second one.
|
|
|
|
@item :
|
|
The range operator. Normally used in the form of array(low:high) to
|
|
represent a section of array.
|
|
|
|
@item %
|
|
The access component operator. Normally used to access elements in derived
|
|
types. Also suitable for unions. As unions aren't part of regular Fortran,
|
|
this can only happen when accessing a register that uses a gdbarch-defined
|
|
union type.
|
|
@end table
|
|
|
|
@node Fortran Defaults
|
|
@subsubsection Fortran Defaults
|
|
|
|
@cindex Fortran Defaults
|
|
|
|
Fortran symbols are usually case-insensitive, so @value{GDBN} by
|
|
default uses case-insensitive matches for Fortran symbols. You can
|
|
change that with the @samp{set case-insensitive} command, see
|
|
@ref{Symbols}, for the details.
|
|
|
|
@node Special Fortran Commands
|
|
@subsubsection Special Fortran Commands
|
|
|
|
@cindex Special Fortran commands
|
|
|
|
@value{GDBN} has some commands to support Fortran-specific features,
|
|
such as displaying common blocks.
|
|
|
|
@table @code
|
|
@cindex @code{COMMON} blocks, Fortran
|
|
@kindex info common
|
|
@item info common @r{[}@var{common-name}@r{]}
|
|
This command prints the values contained in the Fortran @code{COMMON}
|
|
block whose name is @var{common-name}. With no argument, the names of
|
|
all @code{COMMON} blocks visible at the current program location are
|
|
printed.
|
|
@end table
|
|
|
|
@node Pascal
|
|
@subsection Pascal
|
|
|
|
@cindex Pascal support in @value{GDBN}, limitations
|
|
Debugging Pascal programs which use sets, subranges, file variables, or
|
|
nested functions does not currently work. @value{GDBN} does not support
|
|
entering expressions, printing values, or similar features using Pascal
|
|
syntax.
|
|
|
|
The Pascal-specific command @code{set print pascal_static-members}
|
|
controls whether static members of Pascal objects are displayed.
|
|
@xref{Print Settings, pascal_static-members}.
|
|
|
|
@node Modula-2
|
|
@subsection Modula-2
|
|
|
|
@cindex Modula-2, @value{GDBN} support
|
|
|
|
The extensions made to @value{GDBN} to support Modula-2 only support
|
|
output from the @sc{gnu} Modula-2 compiler (which is currently being
|
|
developed). Other Modula-2 compilers are not currently supported, and
|
|
attempting to debug executables produced by them is most likely
|
|
to give an error as @value{GDBN} reads in the executable's symbol
|
|
table.
|
|
|
|
@cindex expressions in Modula-2
|
|
@menu
|
|
* M2 Operators:: Built-in operators
|
|
* Built-In Func/Proc:: Built-in functions and procedures
|
|
* M2 Constants:: Modula-2 constants
|
|
* M2 Types:: Modula-2 types
|
|
* M2 Defaults:: Default settings for Modula-2
|
|
* Deviations:: Deviations from standard Modula-2
|
|
* M2 Checks:: Modula-2 type and range checks
|
|
* M2 Scope:: The scope operators @code{::} and @code{.}
|
|
* GDB/M2:: @value{GDBN} and Modula-2
|
|
@end menu
|
|
|
|
@node M2 Operators
|
|
@subsubsection Operators
|
|
@cindex Modula-2 operators
|
|
|
|
Operators must be defined on values of specific types. For instance,
|
|
@code{+} is defined on numbers, but not on structures. Operators are
|
|
often defined on groups of types. For the purposes of Modula-2, the
|
|
following definitions hold:
|
|
|
|
@itemize @bullet
|
|
|
|
@item
|
|
@emph{Integral types} consist of @code{INTEGER}, @code{CARDINAL}, and
|
|
their subranges.
|
|
|
|
@item
|
|
@emph{Character types} consist of @code{CHAR} and its subranges.
|
|
|
|
@item
|
|
@emph{Floating-point types} consist of @code{REAL}.
|
|
|
|
@item
|
|
@emph{Pointer types} consist of anything declared as @code{POINTER TO
|
|
@var{type}}.
|
|
|
|
@item
|
|
@emph{Scalar types} consist of all of the above.
|
|
|
|
@item
|
|
@emph{Set types} consist of @code{SET} and @code{BITSET} types.
|
|
|
|
@item
|
|
@emph{Boolean types} consist of @code{BOOLEAN}.
|
|
@end itemize
|
|
|
|
@noindent
|
|
The following operators are supported, and appear in order of
|
|
increasing precedence:
|
|
|
|
@table @code
|
|
@item ,
|
|
Function argument or array index separator.
|
|
|
|
@item :=
|
|
Assignment. The value of @var{var} @code{:=} @var{value} is
|
|
@var{value}.
|
|
|
|
@item <@r{, }>
|
|
Less than, greater than on integral, floating-point, or enumerated
|
|
types.
|
|
|
|
@item <=@r{, }>=
|
|
Less than or equal to, greater than or equal to
|
|
on integral, floating-point and enumerated types, or set inclusion on
|
|
set types. Same precedence as @code{<}.
|
|
|
|
@item =@r{, }<>@r{, }#
|
|
Equality and two ways of expressing inequality, valid on scalar types.
|
|
Same precedence as @code{<}. In @value{GDBN} scripts, only @code{<>} is
|
|
available for inequality, since @code{#} conflicts with the script
|
|
comment character.
|
|
|
|
@item IN
|
|
Set membership. Defined on set types and the types of their members.
|
|
Same precedence as @code{<}.
|
|
|
|
@item OR
|
|
Boolean disjunction. Defined on boolean types.
|
|
|
|
@item AND@r{, }&
|
|
Boolean conjunction. Defined on boolean types.
|
|
|
|
@item @@
|
|
The @value{GDBN} ``artificial array'' operator (@pxref{Expressions, ,Expressions}).
|
|
|
|
@item +@r{, }-
|
|
Addition and subtraction on integral and floating-point types, or union
|
|
and difference on set types.
|
|
|
|
@item *
|
|
Multiplication on integral and floating-point types, or set intersection
|
|
on set types.
|
|
|
|
@item /
|
|
Division on floating-point types, or symmetric set difference on set
|
|
types. Same precedence as @code{*}.
|
|
|
|
@item DIV@r{, }MOD
|
|
Integer division and remainder. Defined on integral types. Same
|
|
precedence as @code{*}.
|
|
|
|
@item -
|
|
Negative. Defined on @code{INTEGER} and @code{REAL} data.
|
|
|
|
@item ^
|
|
Pointer dereferencing. Defined on pointer types.
|
|
|
|
@item NOT
|
|
Boolean negation. Defined on boolean types. Same precedence as
|
|
@code{^}.
|
|
|
|
@item .
|
|
@code{RECORD} field selector. Defined on @code{RECORD} data. Same
|
|
precedence as @code{^}.
|
|
|
|
@item []
|
|
Array indexing. Defined on @code{ARRAY} data. Same precedence as @code{^}.
|
|
|
|
@item ()
|
|
Procedure argument list. Defined on @code{PROCEDURE} objects. Same precedence
|
|
as @code{^}.
|
|
|
|
@item ::@r{, }.
|
|
@value{GDBN} and Modula-2 scope operators.
|
|
@end table
|
|
|
|
@quotation
|
|
@emph{Warning:} Set expressions and their operations are not yet supported, so @value{GDBN}
|
|
treats the use of the operator @code{IN}, or the use of operators
|
|
@code{+}, @code{-}, @code{*}, @code{/}, @code{=}, , @code{<>}, @code{#},
|
|
@code{<=}, and @code{>=} on sets as an error.
|
|
@end quotation
|
|
|
|
|
|
@node Built-In Func/Proc
|
|
@subsubsection Built-in Functions and Procedures
|
|
@cindex Modula-2 built-ins
|
|
|
|
Modula-2 also makes available several built-in procedures and functions.
|
|
In describing these, the following metavariables are used:
|
|
|
|
@table @var
|
|
|
|
@item a
|
|
represents an @code{ARRAY} variable.
|
|
|
|
@item c
|
|
represents a @code{CHAR} constant or variable.
|
|
|
|
@item i
|
|
represents a variable or constant of integral type.
|
|
|
|
@item m
|
|
represents an identifier that belongs to a set. Generally used in the
|
|
same function with the metavariable @var{s}. The type of @var{s} should
|
|
be @code{SET OF @var{mtype}} (where @var{mtype} is the type of @var{m}).
|
|
|
|
@item n
|
|
represents a variable or constant of integral or floating-point type.
|
|
|
|
@item r
|
|
represents a variable or constant of floating-point type.
|
|
|
|
@item t
|
|
represents a type.
|
|
|
|
@item v
|
|
represents a variable.
|
|
|
|
@item x
|
|
represents a variable or constant of one of many types. See the
|
|
explanation of the function for details.
|
|
@end table
|
|
|
|
All Modula-2 built-in procedures also return a result, described below.
|
|
|
|
@table @code
|
|
@item ABS(@var{n})
|
|
Returns the absolute value of @var{n}.
|
|
|
|
@item CAP(@var{c})
|
|
If @var{c} is a lower case letter, it returns its upper case
|
|
equivalent, otherwise it returns its argument.
|
|
|
|
@item CHR(@var{i})
|
|
Returns the character whose ordinal value is @var{i}.
|
|
|
|
@item DEC(@var{v})
|
|
Decrements the value in the variable @var{v} by one. Returns the new value.
|
|
|
|
@item DEC(@var{v},@var{i})
|
|
Decrements the value in the variable @var{v} by @var{i}. Returns the
|
|
new value.
|
|
|
|
@item EXCL(@var{m},@var{s})
|
|
Removes the element @var{m} from the set @var{s}. Returns the new
|
|
set.
|
|
|
|
@item FLOAT(@var{i})
|
|
Returns the floating point equivalent of the integer @var{i}.
|
|
|
|
@item HIGH(@var{a})
|
|
Returns the index of the last member of @var{a}.
|
|
|
|
@item INC(@var{v})
|
|
Increments the value in the variable @var{v} by one. Returns the new value.
|
|
|
|
@item INC(@var{v},@var{i})
|
|
Increments the value in the variable @var{v} by @var{i}. Returns the
|
|
new value.
|
|
|
|
@item INCL(@var{m},@var{s})
|
|
Adds the element @var{m} to the set @var{s} if it is not already
|
|
there. Returns the new set.
|
|
|
|
@item MAX(@var{t})
|
|
Returns the maximum value of the type @var{t}.
|
|
|
|
@item MIN(@var{t})
|
|
Returns the minimum value of the type @var{t}.
|
|
|
|
@item ODD(@var{i})
|
|
Returns boolean TRUE if @var{i} is an odd number.
|
|
|
|
@item ORD(@var{x})
|
|
Returns the ordinal value of its argument. For example, the ordinal
|
|
value of a character is its @sc{ascii} value (on machines supporting the
|
|
@sc{ascii} character set). @var{x} must be of an ordered type, which include
|
|
integral, character and enumerated types.
|
|
|
|
@item SIZE(@var{x})
|
|
Returns the size of its argument. @var{x} can be a variable or a type.
|
|
|
|
@item TRUNC(@var{r})
|
|
Returns the integral part of @var{r}.
|
|
|
|
@item TSIZE(@var{x})
|
|
Returns the size of its argument. @var{x} can be a variable or a type.
|
|
|
|
@item VAL(@var{t},@var{i})
|
|
Returns the member of the type @var{t} whose ordinal value is @var{i}.
|
|
@end table
|
|
|
|
@quotation
|
|
@emph{Warning:} Sets and their operations are not yet supported, so
|
|
@value{GDBN} treats the use of procedures @code{INCL} and @code{EXCL} as
|
|
an error.
|
|
@end quotation
|
|
|
|
@cindex Modula-2 constants
|
|
@node M2 Constants
|
|
@subsubsection Constants
|
|
|
|
@value{GDBN} allows you to express the constants of Modula-2 in the following
|
|
ways:
|
|
|
|
@itemize @bullet
|
|
|
|
@item
|
|
Integer constants are simply a sequence of digits. When used in an
|
|
expression, a constant is interpreted to be type-compatible with the
|
|
rest of the expression. Hexadecimal integers are specified by a
|
|
trailing @samp{H}, and octal integers by a trailing @samp{B}.
|
|
|
|
@item
|
|
Floating point constants appear as a sequence of digits, followed by a
|
|
decimal point and another sequence of digits. An optional exponent can
|
|
then be specified, in the form @samp{E@r{[}+@r{|}-@r{]}@var{nnn}}, where
|
|
@samp{@r{[}+@r{|}-@r{]}@var{nnn}} is the desired exponent. All of the
|
|
digits of the floating point constant must be valid decimal (base 10)
|
|
digits.
|
|
|
|
@item
|
|
Character constants consist of a single character enclosed by a pair of
|
|
like quotes, either single (@code{'}) or double (@code{"}). They may
|
|
also be expressed by their ordinal value (their @sc{ascii} value, usually)
|
|
followed by a @samp{C}.
|
|
|
|
@item
|
|
String constants consist of a sequence of characters enclosed by a
|
|
pair of like quotes, either single (@code{'}) or double (@code{"}).
|
|
Escape sequences in the style of C are also allowed. @xref{C
|
|
Constants, ,C and C@t{++} Constants}, for a brief explanation of escape
|
|
sequences.
|
|
|
|
@item
|
|
Enumerated constants consist of an enumerated identifier.
|
|
|
|
@item
|
|
Boolean constants consist of the identifiers @code{TRUE} and
|
|
@code{FALSE}.
|
|
|
|
@item
|
|
Pointer constants consist of integral values only.
|
|
|
|
@item
|
|
Set constants are not yet supported.
|
|
@end itemize
|
|
|
|
@node M2 Types
|
|
@subsubsection Modula-2 Types
|
|
@cindex Modula-2 types
|
|
|
|
Currently @value{GDBN} can print the following data types in Modula-2
|
|
syntax: array types, record types, set types, pointer types, procedure
|
|
types, enumerated types, subrange types and base types. You can also
|
|
print the contents of variables declared using these type.
|
|
This section gives a number of simple source code examples together with
|
|
sample @value{GDBN} sessions.
|
|
|
|
The first example contains the following section of code:
|
|
|
|
@smallexample
|
|
VAR
|
|
s: SET OF CHAR ;
|
|
r: [20..40] ;
|
|
@end smallexample
|
|
|
|
@noindent
|
|
and you can request @value{GDBN} to interrogate the type and value of
|
|
@code{r} and @code{s}.
|
|
|
|
@smallexample
|
|
(@value{GDBP}) print s
|
|
@{'A'..'C', 'Z'@}
|
|
(@value{GDBP}) ptype s
|
|
SET OF CHAR
|
|
(@value{GDBP}) print r
|
|
21
|
|
(@value{GDBP}) ptype r
|
|
[20..40]
|
|
@end smallexample
|
|
|
|
@noindent
|
|
Likewise if your source code declares @code{s} as:
|
|
|
|
@smallexample
|
|
VAR
|
|
s: SET ['A'..'Z'] ;
|
|
@end smallexample
|
|
|
|
@noindent
|
|
then you may query the type of @code{s} by:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) ptype s
|
|
type = SET ['A'..'Z']
|
|
@end smallexample
|
|
|
|
@noindent
|
|
Note that at present you cannot interactively manipulate set
|
|
expressions using the debugger.
|
|
|
|
The following example shows how you might declare an array in Modula-2
|
|
and how you can interact with @value{GDBN} to print its type and contents:
|
|
|
|
@smallexample
|
|
VAR
|
|
s: ARRAY [-10..10] OF CHAR ;
|
|
@end smallexample
|
|
|
|
@smallexample
|
|
(@value{GDBP}) ptype s
|
|
ARRAY [-10..10] OF CHAR
|
|
@end smallexample
|
|
|
|
Note that the array handling is not yet complete and although the type
|
|
is printed correctly, expression handling still assumes that all
|
|
arrays have a lower bound of zero and not @code{-10} as in the example
|
|
above.
|
|
|
|
Here are some more type related Modula-2 examples:
|
|
|
|
@smallexample
|
|
TYPE
|
|
colour = (blue, red, yellow, green) ;
|
|
t = [blue..yellow] ;
|
|
VAR
|
|
s: t ;
|
|
BEGIN
|
|
s := blue ;
|
|
@end smallexample
|
|
|
|
@noindent
|
|
The @value{GDBN} interaction shows how you can query the data type
|
|
and value of a variable.
|
|
|
|
@smallexample
|
|
(@value{GDBP}) print s
|
|
$1 = blue
|
|
(@value{GDBP}) ptype t
|
|
type = [blue..yellow]
|
|
@end smallexample
|
|
|
|
@noindent
|
|
In this example a Modula-2 array is declared and its contents
|
|
displayed. Observe that the contents are written in the same way as
|
|
their @code{C} counterparts.
|
|
|
|
@smallexample
|
|
VAR
|
|
s: ARRAY [1..5] OF CARDINAL ;
|
|
BEGIN
|
|
s[1] := 1 ;
|
|
@end smallexample
|
|
|
|
@smallexample
|
|
(@value{GDBP}) print s
|
|
$1 = @{1, 0, 0, 0, 0@}
|
|
(@value{GDBP}) ptype s
|
|
type = ARRAY [1..5] OF CARDINAL
|
|
@end smallexample
|
|
|
|
The Modula-2 language interface to @value{GDBN} also understands
|
|
pointer types as shown in this example:
|
|
|
|
@smallexample
|
|
VAR
|
|
s: POINTER TO ARRAY [1..5] OF CARDINAL ;
|
|
BEGIN
|
|
NEW(s) ;
|
|
s^[1] := 1 ;
|
|
@end smallexample
|
|
|
|
@noindent
|
|
and you can request that @value{GDBN} describes the type of @code{s}.
|
|
|
|
@smallexample
|
|
(@value{GDBP}) ptype s
|
|
type = POINTER TO ARRAY [1..5] OF CARDINAL
|
|
@end smallexample
|
|
|
|
@value{GDBN} handles compound types as we can see in this example.
|
|
Here we combine array types, record types, pointer types and subrange
|
|
types:
|
|
|
|
@smallexample
|
|
TYPE
|
|
foo = RECORD
|
|
f1: CARDINAL ;
|
|
f2: CHAR ;
|
|
f3: myarray ;
|
|
END ;
|
|
|
|
myarray = ARRAY myrange OF CARDINAL ;
|
|
myrange = [-2..2] ;
|
|
VAR
|
|
s: POINTER TO ARRAY myrange OF foo ;
|
|
@end smallexample
|
|
|
|
@noindent
|
|
and you can ask @value{GDBN} to describe the type of @code{s} as shown
|
|
below.
|
|
|
|
@smallexample
|
|
(@value{GDBP}) ptype s
|
|
type = POINTER TO ARRAY [-2..2] OF foo = RECORD
|
|
f1 : CARDINAL;
|
|
f2 : CHAR;
|
|
f3 : ARRAY [-2..2] OF CARDINAL;
|
|
END
|
|
@end smallexample
|
|
|
|
@node M2 Defaults
|
|
@subsubsection Modula-2 Defaults
|
|
@cindex Modula-2 defaults
|
|
|
|
If type and range checking are set automatically by @value{GDBN}, they
|
|
both default to @code{on} whenever the working language changes to
|
|
Modula-2. This happens regardless of whether you or @value{GDBN}
|
|
selected the working language.
|
|
|
|
If you allow @value{GDBN} to set the language automatically, then entering
|
|
code compiled from a file whose name ends with @file{.mod} sets the
|
|
working language to Modula-2. @xref{Automatically, ,Having @value{GDBN}
|
|
Infer the Source Language}, for further details.
|
|
|
|
@node Deviations
|
|
@subsubsection Deviations from Standard Modula-2
|
|
@cindex Modula-2, deviations from
|
|
|
|
A few changes have been made to make Modula-2 programs easier to debug.
|
|
This is done primarily via loosening its type strictness:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
Unlike in standard Modula-2, pointer constants can be formed by
|
|
integers. This allows you to modify pointer variables during
|
|
debugging. (In standard Modula-2, the actual address contained in a
|
|
pointer variable is hidden from you; it can only be modified
|
|
through direct assignment to another pointer variable or expression that
|
|
returned a pointer.)
|
|
|
|
@item
|
|
C escape sequences can be used in strings and characters to represent
|
|
non-printable characters. @value{GDBN} prints out strings with these
|
|
escape sequences embedded. Single non-printable characters are
|
|
printed using the @samp{CHR(@var{nnn})} format.
|
|
|
|
@item
|
|
The assignment operator (@code{:=}) returns the value of its right-hand
|
|
argument.
|
|
|
|
@item
|
|
All built-in procedures both modify @emph{and} return their argument.
|
|
@end itemize
|
|
|
|
@node M2 Checks
|
|
@subsubsection Modula-2 Type and Range Checks
|
|
@cindex Modula-2 checks
|
|
|
|
@quotation
|
|
@emph{Warning:} in this release, @value{GDBN} does not yet perform type or
|
|
range checking.
|
|
@end quotation
|
|
@c FIXME remove warning when type/range checks added
|
|
|
|
@value{GDBN} considers two Modula-2 variables type equivalent if:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
They are of types that have been declared equivalent via a @code{TYPE
|
|
@var{t1} = @var{t2}} statement
|
|
|
|
@item
|
|
They have been declared on the same line. (Note: This is true of the
|
|
@sc{gnu} Modula-2 compiler, but it may not be true of other compilers.)
|
|
@end itemize
|
|
|
|
As long as type checking is enabled, any attempt to combine variables
|
|
whose types are not equivalent is an error.
|
|
|
|
Range checking is done on all mathematical operations, assignment, array
|
|
index bounds, and all built-in functions and procedures.
|
|
|
|
@node M2 Scope
|
|
@subsubsection The Scope Operators @code{::} and @code{.}
|
|
@cindex scope
|
|
@cindex @code{.}, Modula-2 scope operator
|
|
@cindex colon, doubled as scope operator
|
|
@ifinfo
|
|
@vindex colon-colon@r{, in Modula-2}
|
|
@c Info cannot handle :: but TeX can.
|
|
@end ifinfo
|
|
@ifnotinfo
|
|
@vindex ::@r{, in Modula-2}
|
|
@end ifnotinfo
|
|
|
|
There are a few subtle differences between the Modula-2 scope operator
|
|
(@code{.}) and the @value{GDBN} scope operator (@code{::}). The two have
|
|
similar syntax:
|
|
|
|
@smallexample
|
|
|
|
@var{module} . @var{id}
|
|
@var{scope} :: @var{id}
|
|
@end smallexample
|
|
|
|
@noindent
|
|
where @var{scope} is the name of a module or a procedure,
|
|
@var{module} the name of a module, and @var{id} is any declared
|
|
identifier within your program, except another module.
|
|
|
|
Using the @code{::} operator makes @value{GDBN} search the scope
|
|
specified by @var{scope} for the identifier @var{id}. If it is not
|
|
found in the specified scope, then @value{GDBN} searches all scopes
|
|
enclosing the one specified by @var{scope}.
|
|
|
|
Using the @code{.} operator makes @value{GDBN} search the current scope for
|
|
the identifier specified by @var{id} that was imported from the
|
|
definition module specified by @var{module}. With this operator, it is
|
|
an error if the identifier @var{id} was not imported from definition
|
|
module @var{module}, or if @var{id} is not an identifier in
|
|
@var{module}.
|
|
|
|
@node GDB/M2
|
|
@subsubsection @value{GDBN} and Modula-2
|
|
|
|
Some @value{GDBN} commands have little use when debugging Modula-2 programs.
|
|
Five subcommands of @code{set print} and @code{show print} apply
|
|
specifically to C and C@t{++}: @samp{vtbl}, @samp{demangle},
|
|
@samp{asm-demangle}, @samp{object}, and @samp{union}. The first four
|
|
apply to C@t{++}, and the last to the C @code{union} type, which has no direct
|
|
analogue in Modula-2.
|
|
|
|
The @code{@@} operator (@pxref{Expressions, ,Expressions}), while available
|
|
with any language, is not useful with Modula-2. Its
|
|
intent is to aid the debugging of @dfn{dynamic arrays}, which cannot be
|
|
created in Modula-2 as they can in C or C@t{++}. However, because an
|
|
address can be specified by an integral constant, the construct
|
|
@samp{@{@var{type}@}@var{adrexp}} is still useful.
|
|
|
|
@cindex @code{#} in Modula-2
|
|
In @value{GDBN} scripts, the Modula-2 inequality operator @code{#} is
|
|
interpreted as the beginning of a comment. Use @code{<>} instead.
|
|
|
|
@node Ada
|
|
@subsection Ada
|
|
@cindex Ada
|
|
|
|
The extensions made to @value{GDBN} for Ada only support
|
|
output from the @sc{gnu} Ada (GNAT) compiler.
|
|
Other Ada compilers are not currently supported, and
|
|
attempting to debug executables produced by them is most likely
|
|
to be difficult.
|
|
|
|
|
|
@cindex expressions in Ada
|
|
@menu
|
|
* Ada Mode Intro:: General remarks on the Ada syntax
|
|
and semantics supported by Ada mode
|
|
in @value{GDBN}.
|
|
* Omissions from Ada:: Restrictions on the Ada expression syntax.
|
|
* Additions to Ada:: Extensions of the Ada expression syntax.
|
|
* Stopping Before Main Program:: Debugging the program during elaboration.
|
|
* Ada Tasks:: Listing and setting breakpoints in tasks.
|
|
* Ada Tasks and Core Files:: Tasking Support when Debugging Core Files
|
|
* Ravenscar Profile:: Tasking Support when using the Ravenscar
|
|
Profile
|
|
* Ada Glitches:: Known peculiarities of Ada mode.
|
|
@end menu
|
|
|
|
@node Ada Mode Intro
|
|
@subsubsection Introduction
|
|
@cindex Ada mode, general
|
|
|
|
The Ada mode of @value{GDBN} supports a fairly large subset of Ada expression
|
|
syntax, with some extensions.
|
|
The philosophy behind the design of this subset is
|
|
|
|
@itemize @bullet
|
|
@item
|
|
That @value{GDBN} should provide basic literals and access to operations for
|
|
arithmetic, dereferencing, field selection, indexing, and subprogram calls,
|
|
leaving more sophisticated computations to subprograms written into the
|
|
program (which therefore may be called from @value{GDBN}).
|
|
|
|
@item
|
|
That type safety and strict adherence to Ada language restrictions
|
|
are not particularly important to the @value{GDBN} user.
|
|
|
|
@item
|
|
That brevity is important to the @value{GDBN} user.
|
|
@end itemize
|
|
|
|
Thus, for brevity, the debugger acts as if all names declared in
|
|
user-written packages are directly visible, even if they are not visible
|
|
according to Ada rules, thus making it unnecessary to fully qualify most
|
|
names with their packages, regardless of context. Where this causes
|
|
ambiguity, @value{GDBN} asks the user's intent.
|
|
|
|
The debugger will start in Ada mode if it detects an Ada main program.
|
|
As for other languages, it will enter Ada mode when stopped in a program that
|
|
was translated from an Ada source file.
|
|
|
|
While in Ada mode, you may use `@t{--}' for comments. This is useful
|
|
mostly for documenting command files. The standard @value{GDBN} comment
|
|
(@samp{#}) still works at the beginning of a line in Ada mode, but not in the
|
|
middle (to allow based literals).
|
|
|
|
The debugger supports limited overloading. Given a subprogram call in which
|
|
the function symbol has multiple definitions, it will use the number of
|
|
actual parameters and some information about their types to attempt to narrow
|
|
the set of definitions. It also makes very limited use of context, preferring
|
|
procedures to functions in the context of the @code{call} command, and
|
|
functions to procedures elsewhere.
|
|
|
|
@node Omissions from Ada
|
|
@subsubsection Omissions from Ada
|
|
@cindex Ada, omissions from
|
|
|
|
Here are the notable omissions from the subset:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
Only a subset of the attributes are supported:
|
|
|
|
@itemize @minus
|
|
@item
|
|
@t{'First}, @t{'Last}, and @t{'Length}
|
|
on array objects (not on types and subtypes).
|
|
|
|
@item
|
|
@t{'Min} and @t{'Max}.
|
|
|
|
@item
|
|
@t{'Pos} and @t{'Val}.
|
|
|
|
@item
|
|
@t{'Tag}.
|
|
|
|
@item
|
|
@t{'Range} on array objects (not subtypes), but only as the right
|
|
operand of the membership (@code{in}) operator.
|
|
|
|
@item
|
|
@t{'Access}, @t{'Unchecked_Access}, and
|
|
@t{'Unrestricted_Access} (a GNAT extension).
|
|
|
|
@item
|
|
@t{'Address}.
|
|
@end itemize
|
|
|
|
@item
|
|
The names in
|
|
@code{Characters.Latin_1} are not available and
|
|
concatenation is not implemented. Thus, escape characters in strings are
|
|
not currently available.
|
|
|
|
@item
|
|
Equality tests (@samp{=} and @samp{/=}) on arrays test for bitwise
|
|
equality of representations. They will generally work correctly
|
|
for strings and arrays whose elements have integer or enumeration types.
|
|
They may not work correctly for arrays whose element
|
|
types have user-defined equality, for arrays of real values
|
|
(in particular, IEEE-conformant floating point, because of negative
|
|
zeroes and NaNs), and for arrays whose elements contain unused bits with
|
|
indeterminate values.
|
|
|
|
@item
|
|
The other component-by-component array operations (@code{and}, @code{or},
|
|
@code{xor}, @code{not}, and relational tests other than equality)
|
|
are not implemented.
|
|
|
|
@item
|
|
@cindex array aggregates (Ada)
|
|
@cindex record aggregates (Ada)
|
|
@cindex aggregates (Ada)
|
|
There is limited support for array and record aggregates. They are
|
|
permitted only on the right sides of assignments, as in these examples:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) set An_Array := (1, 2, 3, 4, 5, 6)
|
|
(@value{GDBP}) set An_Array := (1, others => 0)
|
|
(@value{GDBP}) set An_Array := (0|4 => 1, 1..3 => 2, 5 => 6)
|
|
(@value{GDBP}) set A_2D_Array := ((1, 2, 3), (4, 5, 6), (7, 8, 9))
|
|
(@value{GDBP}) set A_Record := (1, "Peter", True);
|
|
(@value{GDBP}) set A_Record := (Name => "Peter", Id => 1, Alive => True)
|
|
@end smallexample
|
|
|
|
Changing a
|
|
discriminant's value by assigning an aggregate has an
|
|
undefined effect if that discriminant is used within the record.
|
|
However, you can first modify discriminants by directly assigning to
|
|
them (which normally would not be allowed in Ada), and then performing an
|
|
aggregate assignment. For example, given a variable @code{A_Rec}
|
|
declared to have a type such as:
|
|
|
|
@smallexample
|
|
type Rec (Len : Small_Integer := 0) is record
|
|
Id : Integer;
|
|
Vals : IntArray (1 .. Len);
|
|
end record;
|
|
@end smallexample
|
|
|
|
you can assign a value with a different size of @code{Vals} with two
|
|
assignments:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) set A_Rec.Len := 4
|
|
(@value{GDBP}) set A_Rec := (Id => 42, Vals => (1, 2, 3, 4))
|
|
@end smallexample
|
|
|
|
As this example also illustrates, @value{GDBN} is very loose about the usual
|
|
rules concerning aggregates. You may leave out some of the
|
|
components of an array or record aggregate (such as the @code{Len}
|
|
component in the assignment to @code{A_Rec} above); they will retain their
|
|
original values upon assignment. You may freely use dynamic values as
|
|
indices in component associations. You may even use overlapping or
|
|
redundant component associations, although which component values are
|
|
assigned in such cases is not defined.
|
|
|
|
@item
|
|
Calls to dispatching subprograms are not implemented.
|
|
|
|
@item
|
|
The overloading algorithm is much more limited (i.e., less selective)
|
|
than that of real Ada. It makes only limited use of the context in
|
|
which a subexpression appears to resolve its meaning, and it is much
|
|
looser in its rules for allowing type matches. As a result, some
|
|
function calls will be ambiguous, and the user will be asked to choose
|
|
the proper resolution.
|
|
|
|
@item
|
|
The @code{new} operator is not implemented.
|
|
|
|
@item
|
|
Entry calls are not implemented.
|
|
|
|
@item
|
|
Aside from printing, arithmetic operations on the native VAX floating-point
|
|
formats are not supported.
|
|
|
|
@item
|
|
It is not possible to slice a packed array.
|
|
|
|
@item
|
|
The names @code{True} and @code{False}, when not part of a qualified name,
|
|
are interpreted as if implicitly prefixed by @code{Standard}, regardless of
|
|
context.
|
|
Should your program
|
|
redefine these names in a package or procedure (at best a dubious practice),
|
|
you will have to use fully qualified names to access their new definitions.
|
|
@end itemize
|
|
|
|
@node Additions to Ada
|
|
@subsubsection Additions to Ada
|
|
@cindex Ada, deviations from
|
|
|
|
As it does for other languages, @value{GDBN} makes certain generic
|
|
extensions to Ada (@pxref{Expressions}):
|
|
|
|
@itemize @bullet
|
|
@item
|
|
If the expression @var{E} is a variable residing in memory (typically
|
|
a local variable or array element) and @var{N} is a positive integer,
|
|
then @code{@var{E}@@@var{N}} displays the values of @var{E} and the
|
|
@var{N}-1 adjacent variables following it in memory as an array. In
|
|
Ada, this operator is generally not necessary, since its prime use is
|
|
in displaying parts of an array, and slicing will usually do this in
|
|
Ada. However, there are occasional uses when debugging programs in
|
|
which certain debugging information has been optimized away.
|
|
|
|
@item
|
|
@code{@var{B}::@var{var}} means ``the variable named @var{var} that
|
|
appears in function or file @var{B}.'' When @var{B} is a file name,
|
|
you must typically surround it in single quotes.
|
|
|
|
@item
|
|
The expression @code{@{@var{type}@} @var{addr}} means ``the variable of type
|
|
@var{type} that appears at address @var{addr}.''
|
|
|
|
@item
|
|
A name starting with @samp{$} is a convenience variable
|
|
(@pxref{Convenience Vars}) or a machine register (@pxref{Registers}).
|
|
@end itemize
|
|
|
|
In addition, @value{GDBN} provides a few other shortcuts and outright
|
|
additions specific to Ada:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
The assignment statement is allowed as an expression, returning
|
|
its right-hand operand as its value. Thus, you may enter
|
|
|
|
@smallexample
|
|
(@value{GDBP}) set x := y + 3
|
|
(@value{GDBP}) print A(tmp := y + 1)
|
|
@end smallexample
|
|
|
|
@item
|
|
The semicolon is allowed as an ``operator,'' returning as its value
|
|
the value of its right-hand operand.
|
|
This allows, for example,
|
|
complex conditional breaks:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) break f
|
|
(@value{GDBP}) condition 1 (report(i); k += 1; A(k) > 100)
|
|
@end smallexample
|
|
|
|
@item
|
|
Rather than use catenation and symbolic character names to introduce special
|
|
characters into strings, one may instead use a special bracket notation,
|
|
which is also used to print strings. A sequence of characters of the form
|
|
@samp{["@var{XX}"]} within a string or character literal denotes the
|
|
(single) character whose numeric encoding is @var{XX} in hexadecimal. The
|
|
sequence of characters @samp{["""]} also denotes a single quotation mark
|
|
in strings. For example,
|
|
@smallexample
|
|
"One line.["0a"]Next line.["0a"]"
|
|
@end smallexample
|
|
@noindent
|
|
contains an ASCII newline character (@code{Ada.Characters.Latin_1.LF})
|
|
after each period.
|
|
|
|
@item
|
|
The subtype used as a prefix for the attributes @t{'Pos}, @t{'Min}, and
|
|
@t{'Max} is optional (and is ignored in any case). For example, it is valid
|
|
to write
|
|
|
|
@smallexample
|
|
(@value{GDBP}) print 'max(x, y)
|
|
@end smallexample
|
|
|
|
@item
|
|
When printing arrays, @value{GDBN} uses positional notation when the
|
|
array has a lower bound of 1, and uses a modified named notation otherwise.
|
|
For example, a one-dimensional array of three integers with a lower bound
|
|
of 3 might print as
|
|
|
|
@smallexample
|
|
(3 => 10, 17, 1)
|
|
@end smallexample
|
|
|
|
@noindent
|
|
That is, in contrast to valid Ada, only the first component has a @code{=>}
|
|
clause.
|
|
|
|
@item
|
|
You may abbreviate attributes in expressions with any unique,
|
|
multi-character subsequence of
|
|
their names (an exact match gets preference).
|
|
For example, you may use @t{a'len}, @t{a'gth}, or @t{a'lh}
|
|
in place of @t{a'length}.
|
|
|
|
@item
|
|
@cindex quoting Ada internal identifiers
|
|
Since Ada is case-insensitive, the debugger normally maps identifiers you type
|
|
to lower case. The GNAT compiler uses upper-case characters for
|
|
some of its internal identifiers, which are normally of no interest to users.
|
|
For the rare occasions when you actually have to look at them,
|
|
enclose them in angle brackets to avoid the lower-case mapping.
|
|
For example,
|
|
@smallexample
|
|
(@value{GDBP}) print <JMPBUF_SAVE>[0]
|
|
@end smallexample
|
|
|
|
@item
|
|
Printing an object of class-wide type or dereferencing an
|
|
access-to-class-wide value will display all the components of the object's
|
|
specific type (as indicated by its run-time tag). Likewise, component
|
|
selection on such a value will operate on the specific type of the
|
|
object.
|
|
|
|
@end itemize
|
|
|
|
@node Stopping Before Main Program
|
|
@subsubsection Stopping at the Very Beginning
|
|
|
|
@cindex breakpointing Ada elaboration code
|
|
It is sometimes necessary to debug the program during elaboration, and
|
|
before reaching the main procedure.
|
|
As defined in the Ada Reference
|
|
Manual, the elaboration code is invoked from a procedure called
|
|
@code{adainit}. To run your program up to the beginning of
|
|
elaboration, simply use the following two commands:
|
|
@code{tbreak adainit} and @code{run}.
|
|
|
|
@node Ada Tasks
|
|
@subsubsection Extensions for Ada Tasks
|
|
@cindex Ada, tasking
|
|
|
|
Support for Ada tasks is analogous to that for threads (@pxref{Threads}).
|
|
@value{GDBN} provides the following task-related commands:
|
|
|
|
@table @code
|
|
@kindex info tasks
|
|
@item info tasks
|
|
This command shows a list of current Ada tasks, as in the following example:
|
|
|
|
|
|
@smallexample
|
|
@iftex
|
|
@leftskip=0.5cm
|
|
@end iftex
|
|
(@value{GDBP}) info tasks
|
|
ID TID P-ID Pri State Name
|
|
1 8088000 0 15 Child Activation Wait main_task
|
|
2 80a4000 1 15 Accept Statement b
|
|
3 809a800 1 15 Child Activation Wait a
|
|
* 4 80ae800 3 15 Runnable c
|
|
|
|
@end smallexample
|
|
|
|
@noindent
|
|
In this listing, the asterisk before the last task indicates it to be the
|
|
task currently being inspected.
|
|
|
|
@table @asis
|
|
@item ID
|
|
Represents @value{GDBN}'s internal task number.
|
|
|
|
@item TID
|
|
The Ada task ID.
|
|
|
|
@item P-ID
|
|
The parent's task ID (@value{GDBN}'s internal task number).
|
|
|
|
@item Pri
|
|
The base priority of the task.
|
|
|
|
@item State
|
|
Current state of the task.
|
|
|
|
@table @code
|
|
@item Unactivated
|
|
The task has been created but has not been activated. It cannot be
|
|
executing.
|
|
|
|
@item Runnable
|
|
The task is not blocked for any reason known to Ada. (It may be waiting
|
|
for a mutex, though.) It is conceptually "executing" in normal mode.
|
|
|
|
@item Terminated
|
|
The task is terminated, in the sense of ARM 9.3 (5). Any dependents
|
|
that were waiting on terminate alternatives have been awakened and have
|
|
terminated themselves.
|
|
|
|
@item Child Activation Wait
|
|
The task is waiting for created tasks to complete activation.
|
|
|
|
@item Accept Statement
|
|
The task is waiting on an accept or selective wait statement.
|
|
|
|
@item Waiting on entry call
|
|
The task is waiting on an entry call.
|
|
|
|
@item Async Select Wait
|
|
The task is waiting to start the abortable part of an asynchronous
|
|
select statement.
|
|
|
|
@item Delay Sleep
|
|
The task is waiting on a select statement with only a delay
|
|
alternative open.
|
|
|
|
@item Child Termination Wait
|
|
The task is sleeping having completed a master within itself, and is
|
|
waiting for the tasks dependent on that master to become terminated or
|
|
waiting on a terminate Phase.
|
|
|
|
@item Wait Child in Term Alt
|
|
The task is sleeping waiting for tasks on terminate alternatives to
|
|
finish terminating.
|
|
|
|
@item Accepting RV with @var{taskno}
|
|
The task is accepting a rendez-vous with the task @var{taskno}.
|
|
@end table
|
|
|
|
@item Name
|
|
Name of the task in the program.
|
|
|
|
@end table
|
|
|
|
@kindex info task @var{taskno}
|
|
@item info task @var{taskno}
|
|
This command shows detailled informations on the specified task, as in
|
|
the following example:
|
|
@smallexample
|
|
@iftex
|
|
@leftskip=0.5cm
|
|
@end iftex
|
|
(@value{GDBP}) info tasks
|
|
ID TID P-ID Pri State Name
|
|
1 8077880 0 15 Child Activation Wait main_task
|
|
* 2 807c468 1 15 Runnable task_1
|
|
(@value{GDBP}) info task 2
|
|
Ada Task: 0x807c468
|
|
Name: task_1
|
|
Thread: 0x807f378
|
|
Parent: 1 (main_task)
|
|
Base Priority: 15
|
|
State: Runnable
|
|
@end smallexample
|
|
|
|
@item task
|
|
@kindex task@r{ (Ada)}
|
|
@cindex current Ada task ID
|
|
This command prints the ID of the current task.
|
|
|
|
@smallexample
|
|
@iftex
|
|
@leftskip=0.5cm
|
|
@end iftex
|
|
(@value{GDBP}) info tasks
|
|
ID TID P-ID Pri State Name
|
|
1 8077870 0 15 Child Activation Wait main_task
|
|
* 2 807c458 1 15 Runnable t
|
|
(@value{GDBP}) task
|
|
[Current task is 2]
|
|
@end smallexample
|
|
|
|
@item task @var{taskno}
|
|
@cindex Ada task switching
|
|
This command is like the @code{thread @var{threadno}}
|
|
command (@pxref{Threads}). It switches the context of debugging
|
|
from the current task to the given task.
|
|
|
|
@smallexample
|
|
@iftex
|
|
@leftskip=0.5cm
|
|
@end iftex
|
|
(@value{GDBP}) info tasks
|
|
ID TID P-ID Pri State Name
|
|
1 8077870 0 15 Child Activation Wait main_task
|
|
* 2 807c458 1 15 Runnable t
|
|
(@value{GDBP}) task 1
|
|
[Switching to task 1]
|
|
#0 0x8067726 in pthread_cond_wait ()
|
|
(@value{GDBP}) bt
|
|
#0 0x8067726 in pthread_cond_wait ()
|
|
#1 0x8056714 in system.os_interface.pthread_cond_wait ()
|
|
#2 0x805cb63 in system.task_primitives.operations.sleep ()
|
|
#3 0x806153e in system.tasking.stages.activate_tasks ()
|
|
#4 0x804aacc in un () at un.adb:5
|
|
@end smallexample
|
|
|
|
@item break @var{linespec} task @var{taskno}
|
|
@itemx break @var{linespec} task @var{taskno} if @dots{}
|
|
@cindex breakpoints and tasks, in Ada
|
|
@cindex task breakpoints, in Ada
|
|
@kindex break @dots{} task @var{taskno}@r{ (Ada)}
|
|
These commands are like the @code{break @dots{} thread @dots{}}
|
|
command (@pxref{Thread Stops}).
|
|
@var{linespec} specifies source lines, as described
|
|
in @ref{Specify Location}.
|
|
|
|
Use the qualifier @samp{task @var{taskno}} with a breakpoint command
|
|
to specify that you only want @value{GDBN} to stop the program when a
|
|
particular Ada task reaches this breakpoint. @var{taskno} is one of the
|
|
numeric task identifiers assigned by @value{GDBN}, shown in the first
|
|
column of the @samp{info tasks} display.
|
|
|
|
If you do not specify @samp{task @var{taskno}} when you set a
|
|
breakpoint, the breakpoint applies to @emph{all} tasks of your
|
|
program.
|
|
|
|
You can use the @code{task} qualifier on conditional breakpoints as
|
|
well; in this case, place @samp{task @var{taskno}} before the
|
|
breakpoint condition (before the @code{if}).
|
|
|
|
For example,
|
|
|
|
@smallexample
|
|
@iftex
|
|
@leftskip=0.5cm
|
|
@end iftex
|
|
(@value{GDBP}) info tasks
|
|
ID TID P-ID Pri State Name
|
|
1 140022020 0 15 Child Activation Wait main_task
|
|
2 140045060 1 15 Accept/Select Wait t2
|
|
3 140044840 1 15 Runnable t1
|
|
* 4 140056040 1 15 Runnable t3
|
|
(@value{GDBP}) b 15 task 2
|
|
Breakpoint 5 at 0x120044cb0: file test_task_debug.adb, line 15.
|
|
(@value{GDBP}) cont
|
|
Continuing.
|
|
task # 1 running
|
|
task # 2 running
|
|
|
|
Breakpoint 5, test_task_debug () at test_task_debug.adb:15
|
|
15 flush;
|
|
(@value{GDBP}) info tasks
|
|
ID TID P-ID Pri State Name
|
|
1 140022020 0 15 Child Activation Wait main_task
|
|
* 2 140045060 1 15 Runnable t2
|
|
3 140044840 1 15 Runnable t1
|
|
4 140056040 1 15 Delay Sleep t3
|
|
@end smallexample
|
|
@end table
|
|
|
|
@node Ada Tasks and Core Files
|
|
@subsubsection Tasking Support when Debugging Core Files
|
|
@cindex Ada tasking and core file debugging
|
|
|
|
When inspecting a core file, as opposed to debugging a live program,
|
|
tasking support may be limited or even unavailable, depending on
|
|
the platform being used.
|
|
For instance, on x86-linux, the list of tasks is available, but task
|
|
switching is not supported. On Tru64, however, task switching will work
|
|
as usual.
|
|
|
|
On certain platforms, including Tru64, the debugger needs to perform some
|
|
memory writes in order to provide Ada tasking support. When inspecting
|
|
a core file, this means that the core file must be opened with read-write
|
|
privileges, using the command @samp{"set write on"} (@pxref{Patching}).
|
|
Under these circumstances, you should make a backup copy of the core
|
|
file before inspecting it with @value{GDBN}.
|
|
|
|
@node Ravenscar Profile
|
|
@subsubsection Tasking Support when using the Ravenscar Profile
|
|
@cindex Ravenscar Profile
|
|
|
|
The @dfn{Ravenscar Profile} is a subset of the Ada tasking features,
|
|
specifically designed for systems with safety-critical real-time
|
|
requirements.
|
|
|
|
@table @code
|
|
@kindex set ravenscar task-switching on
|
|
@cindex task switching with program using Ravenscar Profile
|
|
@item set ravenscar task-switching on
|
|
Allows task switching when debugging a program that uses the Ravenscar
|
|
Profile. This is the default.
|
|
|
|
@kindex set ravenscar task-switching off
|
|
@item set ravenscar task-switching off
|
|
Turn off task switching when debugging a program that uses the Ravenscar
|
|
Profile. This is mostly intended to disable the code that adds support
|
|
for the Ravenscar Profile, in case a bug in either @value{GDBN} or in
|
|
the Ravenscar runtime is preventing @value{GDBN} from working properly.
|
|
To be effective, this command should be run before the program is started.
|
|
|
|
@kindex show ravenscar task-switching
|
|
@item show ravenscar task-switching
|
|
Show whether it is possible to switch from task to task in a program
|
|
using the Ravenscar Profile.
|
|
|
|
@end table
|
|
|
|
@node Ada Glitches
|
|
@subsubsection Known Peculiarities of Ada Mode
|
|
@cindex Ada, problems
|
|
|
|
Besides the omissions listed previously (@pxref{Omissions from Ada}),
|
|
we know of several problems with and limitations of Ada mode in
|
|
@value{GDBN},
|
|
some of which will be fixed with planned future releases of the debugger
|
|
and the GNU Ada compiler.
|
|
|
|
@itemize @bullet
|
|
@item
|
|
Static constants that the compiler chooses not to materialize as objects in
|
|
storage are invisible to the debugger.
|
|
|
|
@item
|
|
Named parameter associations in function argument lists are ignored (the
|
|
argument lists are treated as positional).
|
|
|
|
@item
|
|
Many useful library packages are currently invisible to the debugger.
|
|
|
|
@item
|
|
Fixed-point arithmetic, conversions, input, and output is carried out using
|
|
floating-point arithmetic, and may give results that only approximate those on
|
|
the host machine.
|
|
|
|
@item
|
|
The GNAT compiler never generates the prefix @code{Standard} for any of
|
|
the standard symbols defined by the Ada language. @value{GDBN} knows about
|
|
this: it will strip the prefix from names when you use it, and will never
|
|
look for a name you have so qualified among local symbols, nor match against
|
|
symbols in other packages or subprograms. If you have
|
|
defined entities anywhere in your program other than parameters and
|
|
local variables whose simple names match names in @code{Standard},
|
|
GNAT's lack of qualification here can cause confusion. When this happens,
|
|
you can usually resolve the confusion
|
|
by qualifying the problematic names with package
|
|
@code{Standard} explicitly.
|
|
@end itemize
|
|
|
|
Older versions of the compiler sometimes generate erroneous debugging
|
|
information, resulting in the debugger incorrectly printing the value
|
|
of affected entities. In some cases, the debugger is able to work
|
|
around an issue automatically. In other cases, the debugger is able
|
|
to work around the issue, but the work-around has to be specifically
|
|
enabled.
|
|
|
|
@kindex set ada trust-PAD-over-XVS
|
|
@kindex show ada trust-PAD-over-XVS
|
|
@table @code
|
|
|
|
@item set ada trust-PAD-over-XVS on
|
|
Configure GDB to strictly follow the GNAT encoding when computing the
|
|
value of Ada entities, particularly when @code{PAD} and @code{PAD___XVS}
|
|
types are involved (see @code{ada/exp_dbug.ads} in the GCC sources for
|
|
a complete description of the encoding used by the GNAT compiler).
|
|
This is the default.
|
|
|
|
@item set ada trust-PAD-over-XVS off
|
|
This is related to the encoding using by the GNAT compiler. If @value{GDBN}
|
|
sometimes prints the wrong value for certain entities, changing @code{ada
|
|
trust-PAD-over-XVS} to @code{off} activates a work-around which may fix
|
|
the issue. It is always safe to set @code{ada trust-PAD-over-XVS} to
|
|
@code{off}, but this incurs a slight performance penalty, so it is
|
|
recommended to leave this setting to @code{on} unless necessary.
|
|
|
|
@end table
|
|
|
|
@node Unsupported Languages
|
|
@section Unsupported Languages
|
|
|
|
@cindex unsupported languages
|
|
@cindex minimal language
|
|
In addition to the other fully-supported programming languages,
|
|
@value{GDBN} also provides a pseudo-language, called @code{minimal}.
|
|
It does not represent a real programming language, but provides a set
|
|
of capabilities close to what the C or assembly languages provide.
|
|
This should allow most simple operations to be performed while debugging
|
|
an application that uses a language currently not supported by @value{GDBN}.
|
|
|
|
If the language is set to @code{auto}, @value{GDBN} will automatically
|
|
select this language if the current frame corresponds to an unsupported
|
|
language.
|
|
|
|
@node Symbols
|
|
@chapter Examining the Symbol Table
|
|
|
|
The commands described in this chapter allow you to inquire about the
|
|
symbols (names of variables, functions and types) defined in your
|
|
program. This information is inherent in the text of your program and
|
|
does not change as your program executes. @value{GDBN} finds it in your
|
|
program's symbol table, in the file indicated when you started @value{GDBN}
|
|
(@pxref{File Options, ,Choosing Files}), or by one of the
|
|
file-management commands (@pxref{Files, ,Commands to Specify Files}).
|
|
|
|
@cindex symbol names
|
|
@cindex names of symbols
|
|
@cindex quoting names
|
|
Occasionally, you may need to refer to symbols that contain unusual
|
|
characters, which @value{GDBN} ordinarily treats as word delimiters. The
|
|
most frequent case is in referring to static variables in other
|
|
source files (@pxref{Variables,,Program Variables}). File names
|
|
are recorded in object files as debugging symbols, but @value{GDBN} would
|
|
ordinarily parse a typical file name, like @file{foo.c}, as the three words
|
|
@samp{foo} @samp{.} @samp{c}. To allow @value{GDBN} to recognize
|
|
@samp{foo.c} as a single symbol, enclose it in single quotes; for example,
|
|
|
|
@smallexample
|
|
p 'foo.c'::x
|
|
@end smallexample
|
|
|
|
@noindent
|
|
looks up the value of @code{x} in the scope of the file @file{foo.c}.
|
|
|
|
@table @code
|
|
@cindex case-insensitive symbol names
|
|
@cindex case sensitivity in symbol names
|
|
@kindex set case-sensitive
|
|
@item set case-sensitive on
|
|
@itemx set case-sensitive off
|
|
@itemx set case-sensitive auto
|
|
Normally, when @value{GDBN} looks up symbols, it matches their names
|
|
with case sensitivity determined by the current source language.
|
|
Occasionally, you may wish to control that. The command @code{set
|
|
case-sensitive} lets you do that by specifying @code{on} for
|
|
case-sensitive matches or @code{off} for case-insensitive ones. If
|
|
you specify @code{auto}, case sensitivity is reset to the default
|
|
suitable for the source language. The default is case-sensitive
|
|
matches for all languages except for Fortran, for which the default is
|
|
case-insensitive matches.
|
|
|
|
@kindex show case-sensitive
|
|
@item show case-sensitive
|
|
This command shows the current setting of case sensitivity for symbols
|
|
lookups.
|
|
|
|
@kindex info address
|
|
@cindex address of a symbol
|
|
@item info address @var{symbol}
|
|
Describe where the data for @var{symbol} is stored. For a register
|
|
variable, this says which register it is kept in. For a non-register
|
|
local variable, this prints the stack-frame offset at which the variable
|
|
is always stored.
|
|
|
|
Note the contrast with @samp{print &@var{symbol}}, which does not work
|
|
at all for a register variable, and for a stack local variable prints
|
|
the exact address of the current instantiation of the variable.
|
|
|
|
@kindex info symbol
|
|
@cindex symbol from address
|
|
@cindex closest symbol and offset for an address
|
|
@item info symbol @var{addr}
|
|
Print the name of a symbol which is stored at the address @var{addr}.
|
|
If no symbol is stored exactly at @var{addr}, @value{GDBN} prints the
|
|
nearest symbol and an offset from it:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) info symbol 0x54320
|
|
_initialize_vx + 396 in section .text
|
|
@end smallexample
|
|
|
|
@noindent
|
|
This is the opposite of the @code{info address} command. You can use
|
|
it to find out the name of a variable or a function given its address.
|
|
|
|
For dynamically linked executables, the name of executable or shared
|
|
library containing the symbol is also printed:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) info symbol 0x400225
|
|
_start + 5 in section .text of /tmp/a.out
|
|
(@value{GDBP}) info symbol 0x2aaaac2811cf
|
|
__read_nocancel + 6 in section .text of /usr/lib64/libc.so.6
|
|
@end smallexample
|
|
|
|
@kindex whatis
|
|
@item whatis [@var{arg}]
|
|
Print the data type of @var{arg}, which can be either an expression
|
|
or a name of a data type. With no argument, print the data type of
|
|
@code{$}, the last value in the value history.
|
|
|
|
If @var{arg} is an expression (@pxref{Expressions, ,Expressions}), it
|
|
is not actually evaluated, and any side-effecting operations (such as
|
|
assignments or function calls) inside it do not take place.
|
|
|
|
If @var{arg} is a variable or an expression, @code{whatis} prints its
|
|
literal type as it is used in the source code. If the type was
|
|
defined using a @code{typedef}, @code{whatis} will @emph{not} print
|
|
the data type underlying the @code{typedef}. If the type of the
|
|
variable or the expression is a compound data type, such as
|
|
@code{struct} or @code{class}, @code{whatis} never prints their
|
|
fields or methods. It just prints the @code{struct}/@code{class}
|
|
name (a.k.a.@: its @dfn{tag}). If you want to see the members of
|
|
such a compound data type, use @code{ptype}.
|
|
|
|
If @var{arg} is a type name that was defined using @code{typedef},
|
|
@code{whatis} @dfn{unrolls} only one level of that @code{typedef}.
|
|
Unrolling means that @code{whatis} will show the underlying type used
|
|
in the @code{typedef} declaration of @var{arg}. However, if that
|
|
underlying type is also a @code{typedef}, @code{whatis} will not
|
|
unroll it.
|
|
|
|
For C code, the type names may also have the form @samp{class
|
|
@var{class-name}}, @samp{struct @var{struct-tag}}, @samp{union
|
|
@var{union-tag}} or @samp{enum @var{enum-tag}}.
|
|
|
|
@kindex ptype
|
|
@item ptype [@var{arg}]
|
|
@code{ptype} accepts the same arguments as @code{whatis}, but prints a
|
|
detailed description of the type, instead of just the name of the type.
|
|
@xref{Expressions, ,Expressions}.
|
|
|
|
Contrary to @code{whatis}, @code{ptype} always unrolls any
|
|
@code{typedef}s in its argument declaration, whether the argument is
|
|
a variable, expression, or a data type. This means that @code{ptype}
|
|
of a variable or an expression will not print literally its type as
|
|
present in the source code---use @code{whatis} for that. @code{typedef}s at
|
|
the pointer or reference targets are also unrolled. Only @code{typedef}s of
|
|
fields, methods and inner @code{class typedef}s of @code{struct}s,
|
|
@code{class}es and @code{union}s are not unrolled even with @code{ptype}.
|
|
|
|
For example, for this variable declaration:
|
|
|
|
@smallexample
|
|
typedef double real_t;
|
|
struct complex @{ real_t real; double imag; @};
|
|
typedef struct complex complex_t;
|
|
complex_t var;
|
|
real_t *real_pointer_var;
|
|
@end smallexample
|
|
|
|
@noindent
|
|
the two commands give this output:
|
|
|
|
@smallexample
|
|
@group
|
|
(@value{GDBP}) whatis var
|
|
type = complex_t
|
|
(@value{GDBP}) ptype var
|
|
type = struct complex @{
|
|
real_t real;
|
|
double imag;
|
|
@}
|
|
(@value{GDBP}) whatis complex_t
|
|
type = struct complex
|
|
(@value{GDBP}) whatis struct complex
|
|
type = struct complex
|
|
(@value{GDBP}) ptype struct complex
|
|
type = struct complex @{
|
|
real_t real;
|
|
double imag;
|
|
@}
|
|
(@value{GDBP}) whatis real_pointer_var
|
|
type = real_t *
|
|
(@value{GDBP}) ptype real_pointer_var
|
|
type = double *
|
|
@end group
|
|
@end smallexample
|
|
|
|
@noindent
|
|
As with @code{whatis}, using @code{ptype} without an argument refers to
|
|
the type of @code{$}, the last value in the value history.
|
|
|
|
@cindex incomplete type
|
|
Sometimes, programs use opaque data types or incomplete specifications
|
|
of complex data structure. If the debug information included in the
|
|
program does not allow @value{GDBN} to display a full declaration of
|
|
the data type, it will say @samp{<incomplete type>}. For example,
|
|
given these declarations:
|
|
|
|
@smallexample
|
|
struct foo;
|
|
struct foo *fooptr;
|
|
@end smallexample
|
|
|
|
@noindent
|
|
but no definition for @code{struct foo} itself, @value{GDBN} will say:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) ptype foo
|
|
$1 = <incomplete type>
|
|
@end smallexample
|
|
|
|
@noindent
|
|
``Incomplete type'' is C terminology for data types that are not
|
|
completely specified.
|
|
|
|
@kindex info types
|
|
@item info types @var{regexp}
|
|
@itemx info types
|
|
Print a brief description of all types whose names match the regular
|
|
expression @var{regexp} (or all types in your program, if you supply
|
|
no argument). Each complete typename is matched as though it were a
|
|
complete line; thus, @samp{i type value} gives information on all
|
|
types in your program whose names include the string @code{value}, but
|
|
@samp{i type ^value$} gives information only on types whose complete
|
|
name is @code{value}.
|
|
|
|
This command differs from @code{ptype} in two ways: first, like
|
|
@code{whatis}, it does not print a detailed description; second, it
|
|
lists all source files where a type is defined.
|
|
|
|
@kindex info scope
|
|
@cindex local variables
|
|
@item info scope @var{location}
|
|
List all the variables local to a particular scope. This command
|
|
accepts a @var{location} argument---a function name, a source line, or
|
|
an address preceded by a @samp{*}, and prints all the variables local
|
|
to the scope defined by that location. (@xref{Specify Location}, for
|
|
details about supported forms of @var{location}.) For example:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) @b{info scope command_line_handler}
|
|
Scope for command_line_handler:
|
|
Symbol rl is an argument at stack/frame offset 8, length 4.
|
|
Symbol linebuffer is in static storage at address 0x150a18, length 4.
|
|
Symbol linelength is in static storage at address 0x150a1c, length 4.
|
|
Symbol p is a local variable in register $esi, length 4.
|
|
Symbol p1 is a local variable in register $ebx, length 4.
|
|
Symbol nline is a local variable in register $edx, length 4.
|
|
Symbol repeat is a local variable at frame offset -8, length 4.
|
|
@end smallexample
|
|
|
|
@noindent
|
|
This command is especially useful for determining what data to collect
|
|
during a @dfn{trace experiment}, see @ref{Tracepoint Actions,
|
|
collect}.
|
|
|
|
@kindex info source
|
|
@item info source
|
|
Show information about the current source file---that is, the source file for
|
|
the function containing the current point of execution:
|
|
@itemize @bullet
|
|
@item
|
|
the name of the source file, and the directory containing it,
|
|
@item
|
|
the directory it was compiled in,
|
|
@item
|
|
its length, in lines,
|
|
@item
|
|
which programming language it is written in,
|
|
@item
|
|
whether the executable includes debugging information for that file, and
|
|
if so, what format the information is in (e.g., STABS, Dwarf 2, etc.), and
|
|
@item
|
|
whether the debugging information includes information about
|
|
preprocessor macros.
|
|
@end itemize
|
|
|
|
|
|
@kindex info sources
|
|
@item info sources
|
|
Print the names of all source files in your program for which there is
|
|
debugging information, organized into two lists: files whose symbols
|
|
have already been read, and files whose symbols will be read when needed.
|
|
|
|
@kindex info functions
|
|
@item info functions
|
|
Print the names and data types of all defined functions.
|
|
|
|
@item info functions @var{regexp}
|
|
Print the names and data types of all defined functions
|
|
whose names contain a match for regular expression @var{regexp}.
|
|
Thus, @samp{info fun step} finds all functions whose names
|
|
include @code{step}; @samp{info fun ^step} finds those whose names
|
|
start with @code{step}. If a function name contains characters
|
|
that conflict with the regular expression language (e.g.@:
|
|
@samp{operator*()}), they may be quoted with a backslash.
|
|
|
|
@kindex info variables
|
|
@item info variables
|
|
Print the names and data types of all variables that are defined
|
|
outside of functions (i.e.@: excluding local variables).
|
|
|
|
@item info variables @var{regexp}
|
|
Print the names and data types of all variables (except for local
|
|
variables) whose names contain a match for regular expression
|
|
@var{regexp}.
|
|
|
|
@kindex info classes
|
|
@cindex Objective-C, classes and selectors
|
|
@item info classes
|
|
@itemx info classes @var{regexp}
|
|
Display all Objective-C classes in your program, or
|
|
(with the @var{regexp} argument) all those matching a particular regular
|
|
expression.
|
|
|
|
@kindex info selectors
|
|
@item info selectors
|
|
@itemx info selectors @var{regexp}
|
|
Display all Objective-C selectors in your program, or
|
|
(with the @var{regexp} argument) all those matching a particular regular
|
|
expression.
|
|
|
|
@ignore
|
|
This was never implemented.
|
|
@kindex info methods
|
|
@item info methods
|
|
@itemx info methods @var{regexp}
|
|
The @code{info methods} command permits the user to examine all defined
|
|
methods within C@t{++} program, or (with the @var{regexp} argument) a
|
|
specific set of methods found in the various C@t{++} classes. Many
|
|
C@t{++} classes provide a large number of methods. Thus, the output
|
|
from the @code{ptype} command can be overwhelming and hard to use. The
|
|
@code{info-methods} command filters the methods, printing only those
|
|
which match the regular-expression @var{regexp}.
|
|
@end ignore
|
|
|
|
@cindex opaque data types
|
|
@kindex set opaque-type-resolution
|
|
@item set opaque-type-resolution on
|
|
Tell @value{GDBN} to resolve opaque types. An opaque type is a type
|
|
declared as a pointer to a @code{struct}, @code{class}, or
|
|
@code{union}---for example, @code{struct MyType *}---that is used in one
|
|
source file although the full declaration of @code{struct MyType} is in
|
|
another source file. The default is on.
|
|
|
|
A change in the setting of this subcommand will not take effect until
|
|
the next time symbols for a file are loaded.
|
|
|
|
@item set opaque-type-resolution off
|
|
Tell @value{GDBN} not to resolve opaque types. In this case, the type
|
|
is printed as follows:
|
|
@smallexample
|
|
@{<no data fields>@}
|
|
@end smallexample
|
|
|
|
@kindex show opaque-type-resolution
|
|
@item show opaque-type-resolution
|
|
Show whether opaque types are resolved or not.
|
|
|
|
@kindex maint print symbols
|
|
@cindex symbol dump
|
|
@kindex maint print psymbols
|
|
@cindex partial symbol dump
|
|
@item maint print symbols @var{filename}
|
|
@itemx maint print psymbols @var{filename}
|
|
@itemx maint print msymbols @var{filename}
|
|
Write a dump of debugging symbol data into the file @var{filename}.
|
|
These commands are used to debug the @value{GDBN} symbol-reading code. Only
|
|
symbols with debugging data are included. If you use @samp{maint print
|
|
symbols}, @value{GDBN} includes all the symbols for which it has already
|
|
collected full details: that is, @var{filename} reflects symbols for
|
|
only those files whose symbols @value{GDBN} has read. You can use the
|
|
command @code{info sources} to find out which files these are. If you
|
|
use @samp{maint print psymbols} instead, the dump shows information about
|
|
symbols that @value{GDBN} only knows partially---that is, symbols defined in
|
|
files that @value{GDBN} has skimmed, but not yet read completely. Finally,
|
|
@samp{maint print msymbols} dumps just the minimal symbol information
|
|
required for each object file from which @value{GDBN} has read some symbols.
|
|
@xref{Files, ,Commands to Specify Files}, for a discussion of how
|
|
@value{GDBN} reads symbols (in the description of @code{symbol-file}).
|
|
|
|
@kindex maint info symtabs
|
|
@kindex maint info psymtabs
|
|
@cindex listing @value{GDBN}'s internal symbol tables
|
|
@cindex symbol tables, listing @value{GDBN}'s internal
|
|
@cindex full symbol tables, listing @value{GDBN}'s internal
|
|
@cindex partial symbol tables, listing @value{GDBN}'s internal
|
|
@item maint info symtabs @r{[} @var{regexp} @r{]}
|
|
@itemx maint info psymtabs @r{[} @var{regexp} @r{]}
|
|
|
|
List the @code{struct symtab} or @code{struct partial_symtab}
|
|
structures whose names match @var{regexp}. If @var{regexp} is not
|
|
given, list them all. The output includes expressions which you can
|
|
copy into a @value{GDBN} debugging this one to examine a particular
|
|
structure in more detail. For example:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) maint info psymtabs dwarf2read
|
|
@{ objfile /home/gnu/build/gdb/gdb
|
|
((struct objfile *) 0x82e69d0)
|
|
@{ psymtab /home/gnu/src/gdb/dwarf2read.c
|
|
((struct partial_symtab *) 0x8474b10)
|
|
readin no
|
|
fullname (null)
|
|
text addresses 0x814d3c8 -- 0x8158074
|
|
globals (* (struct partial_symbol **) 0x8507a08 @@ 9)
|
|
statics (* (struct partial_symbol **) 0x40e95b78 @@ 2882)
|
|
dependencies (none)
|
|
@}
|
|
@}
|
|
(@value{GDBP}) maint info symtabs
|
|
(@value{GDBP})
|
|
@end smallexample
|
|
@noindent
|
|
We see that there is one partial symbol table whose filename contains
|
|
the string @samp{dwarf2read}, belonging to the @samp{gdb} executable;
|
|
and we see that @value{GDBN} has not read in any symtabs yet at all.
|
|
If we set a breakpoint on a function, that will cause @value{GDBN} to
|
|
read the symtab for the compilation unit containing that function:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) break dwarf2_psymtab_to_symtab
|
|
Breakpoint 1 at 0x814e5da: file /home/gnu/src/gdb/dwarf2read.c,
|
|
line 1574.
|
|
(@value{GDBP}) maint info symtabs
|
|
@{ objfile /home/gnu/build/gdb/gdb
|
|
((struct objfile *) 0x82e69d0)
|
|
@{ symtab /home/gnu/src/gdb/dwarf2read.c
|
|
((struct symtab *) 0x86c1f38)
|
|
dirname (null)
|
|
fullname (null)
|
|
blockvector ((struct blockvector *) 0x86c1bd0) (primary)
|
|
linetable ((struct linetable *) 0x8370fa0)
|
|
debugformat DWARF 2
|
|
@}
|
|
@}
|
|
(@value{GDBP})
|
|
@end smallexample
|
|
@end table
|
|
|
|
|
|
@node Altering
|
|
@chapter Altering Execution
|
|
|
|
Once you think you have found an error in your program, you might want to
|
|
find out for certain whether correcting the apparent error would lead to
|
|
correct results in the rest of the run. You can find the answer by
|
|
experiment, using the @value{GDBN} features for altering execution of the
|
|
program.
|
|
|
|
For example, you can store new values into variables or memory
|
|
locations, give your program a signal, restart it at a different
|
|
address, or even return prematurely from a function.
|
|
|
|
@menu
|
|
* Assignment:: Assignment to variables
|
|
* Jumping:: Continuing at a different address
|
|
* Signaling:: Giving your program a signal
|
|
* Returning:: Returning from a function
|
|
* Calling:: Calling your program's functions
|
|
* Patching:: Patching your program
|
|
@end menu
|
|
|
|
@node Assignment
|
|
@section Assignment to Variables
|
|
|
|
@cindex assignment
|
|
@cindex setting variables
|
|
To alter the value of a variable, evaluate an assignment expression.
|
|
@xref{Expressions, ,Expressions}. For example,
|
|
|
|
@smallexample
|
|
print x=4
|
|
@end smallexample
|
|
|
|
@noindent
|
|
stores the value 4 into the variable @code{x}, and then prints the
|
|
value of the assignment expression (which is 4).
|
|
@xref{Languages, ,Using @value{GDBN} with Different Languages}, for more
|
|
information on operators in supported languages.
|
|
|
|
@kindex set variable
|
|
@cindex variables, setting
|
|
If you are not interested in seeing the value of the assignment, use the
|
|
@code{set} command instead of the @code{print} command. @code{set} is
|
|
really the same as @code{print} except that the expression's value is
|
|
not printed and is not put in the value history (@pxref{Value History,
|
|
,Value History}). The expression is evaluated only for its effects.
|
|
|
|
If the beginning of the argument string of the @code{set} command
|
|
appears identical to a @code{set} subcommand, use the @code{set
|
|
variable} command instead of just @code{set}. This command is identical
|
|
to @code{set} except for its lack of subcommands. For example, if your
|
|
program has a variable @code{width}, you get an error if you try to set
|
|
a new value with just @samp{set width=13}, because @value{GDBN} has the
|
|
command @code{set width}:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) whatis width
|
|
type = double
|
|
(@value{GDBP}) p width
|
|
$4 = 13
|
|
(@value{GDBP}) set width=47
|
|
Invalid syntax in expression.
|
|
@end smallexample
|
|
|
|
@noindent
|
|
The invalid expression, of course, is @samp{=47}. In
|
|
order to actually set the program's variable @code{width}, use
|
|
|
|
@smallexample
|
|
(@value{GDBP}) set var width=47
|
|
@end smallexample
|
|
|
|
Because the @code{set} command has many subcommands that can conflict
|
|
with the names of program variables, it is a good idea to use the
|
|
@code{set variable} command instead of just @code{set}. For example, if
|
|
your program has a variable @code{g}, you run into problems if you try
|
|
to set a new value with just @samp{set g=4}, because @value{GDBN} has
|
|
the command @code{set gnutarget}, abbreviated @code{set g}:
|
|
|
|
@smallexample
|
|
@group
|
|
(@value{GDBP}) whatis g
|
|
type = double
|
|
(@value{GDBP}) p g
|
|
$1 = 1
|
|
(@value{GDBP}) set g=4
|
|
(@value{GDBP}) p g
|
|
$2 = 1
|
|
(@value{GDBP}) r
|
|
The program being debugged has been started already.
|
|
Start it from the beginning? (y or n) y
|
|
Starting program: /home/smith/cc_progs/a.out
|
|
"/home/smith/cc_progs/a.out": can't open to read symbols:
|
|
Invalid bfd target.
|
|
(@value{GDBP}) show g
|
|
The current BFD target is "=4".
|
|
@end group
|
|
@end smallexample
|
|
|
|
@noindent
|
|
The program variable @code{g} did not change, and you silently set the
|
|
@code{gnutarget} to an invalid value. In order to set the variable
|
|
@code{g}, use
|
|
|
|
@smallexample
|
|
(@value{GDBP}) set var g=4
|
|
@end smallexample
|
|
|
|
@value{GDBN} allows more implicit conversions in assignments than C; you can
|
|
freely store an integer value into a pointer variable or vice versa,
|
|
and you can convert any structure to any other structure that is the
|
|
same length or shorter.
|
|
@comment FIXME: how do structs align/pad in these conversions?
|
|
@comment /doc@cygnus.com 18dec1990
|
|
|
|
To store values into arbitrary places in memory, use the @samp{@{@dots{}@}}
|
|
construct to generate a value of specified type at a specified address
|
|
(@pxref{Expressions, ,Expressions}). For example, @code{@{int@}0x83040} refers
|
|
to memory location @code{0x83040} as an integer (which implies a certain size
|
|
and representation in memory), and
|
|
|
|
@smallexample
|
|
set @{int@}0x83040 = 4
|
|
@end smallexample
|
|
|
|
@noindent
|
|
stores the value 4 into that memory location.
|
|
|
|
@node Jumping
|
|
@section Continuing at a Different Address
|
|
|
|
Ordinarily, when you continue your program, you do so at the place where
|
|
it stopped, with the @code{continue} command. You can instead continue at
|
|
an address of your own choosing, with the following commands:
|
|
|
|
@table @code
|
|
@kindex jump
|
|
@item jump @var{linespec}
|
|
@itemx jump @var{location}
|
|
Resume execution at line @var{linespec} or at address given by
|
|
@var{location}. Execution stops again immediately if there is a
|
|
breakpoint there. @xref{Specify Location}, for a description of the
|
|
different forms of @var{linespec} and @var{location}. It is common
|
|
practice to use the @code{tbreak} command in conjunction with
|
|
@code{jump}. @xref{Set Breaks, ,Setting Breakpoints}.
|
|
|
|
The @code{jump} command does not change the current stack frame, or
|
|
the stack pointer, or the contents of any memory location or any
|
|
register other than the program counter. If line @var{linespec} is in
|
|
a different function from the one currently executing, the results may
|
|
be bizarre if the two functions expect different patterns of arguments or
|
|
of local variables. For this reason, the @code{jump} command requests
|
|
confirmation if the specified line is not in the function currently
|
|
executing. However, even bizarre results are predictable if you are
|
|
well acquainted with the machine-language code of your program.
|
|
@end table
|
|
|
|
@c Doesn't work on HP-UX; have to set $pcoqh and $pcoqt.
|
|
On many systems, you can get much the same effect as the @code{jump}
|
|
command by storing a new value into the register @code{$pc}. The
|
|
difference is that this does not start your program running; it only
|
|
changes the address of where it @emph{will} run when you continue. For
|
|
example,
|
|
|
|
@smallexample
|
|
set $pc = 0x485
|
|
@end smallexample
|
|
|
|
@noindent
|
|
makes the next @code{continue} command or stepping command execute at
|
|
address @code{0x485}, rather than at the address where your program stopped.
|
|
@xref{Continuing and Stepping, ,Continuing and Stepping}.
|
|
|
|
The most common occasion to use the @code{jump} command is to back
|
|
up---perhaps with more breakpoints set---over a portion of a program
|
|
that has already executed, in order to examine its execution in more
|
|
detail.
|
|
|
|
@c @group
|
|
@node Signaling
|
|
@section Giving your Program a Signal
|
|
@cindex deliver a signal to a program
|
|
|
|
@table @code
|
|
@kindex signal
|
|
@item signal @var{signal}
|
|
Resume execution where your program stopped, but immediately give it the
|
|
signal @var{signal}. @var{signal} can be the name or the number of a
|
|
signal. For example, on many systems @code{signal 2} and @code{signal
|
|
SIGINT} are both ways of sending an interrupt signal.
|
|
|
|
Alternatively, if @var{signal} is zero, continue execution without
|
|
giving a signal. This is useful when your program stopped on account of
|
|
a signal and would ordinary see the signal when resumed with the
|
|
@code{continue} command; @samp{signal 0} causes it to resume without a
|
|
signal.
|
|
|
|
@code{signal} does not repeat when you press @key{RET} a second time
|
|
after executing the command.
|
|
@end table
|
|
@c @end group
|
|
|
|
Invoking the @code{signal} command is not the same as invoking the
|
|
@code{kill} utility from the shell. Sending a signal with @code{kill}
|
|
causes @value{GDBN} to decide what to do with the signal depending on
|
|
the signal handling tables (@pxref{Signals}). The @code{signal} command
|
|
passes the signal directly to your program.
|
|
|
|
|
|
@node Returning
|
|
@section Returning from a Function
|
|
|
|
@table @code
|
|
@cindex returning from a function
|
|
@kindex return
|
|
@item return
|
|
@itemx return @var{expression}
|
|
You can cancel execution of a function call with the @code{return}
|
|
command. If you give an
|
|
@var{expression} argument, its value is used as the function's return
|
|
value.
|
|
@end table
|
|
|
|
When you use @code{return}, @value{GDBN} discards the selected stack frame
|
|
(and all frames within it). You can think of this as making the
|
|
discarded frame return prematurely. If you wish to specify a value to
|
|
be returned, give that value as the argument to @code{return}.
|
|
|
|
This pops the selected stack frame (@pxref{Selection, ,Selecting a
|
|
Frame}), and any other frames inside of it, leaving its caller as the
|
|
innermost remaining frame. That frame becomes selected. The
|
|
specified value is stored in the registers used for returning values
|
|
of functions.
|
|
|
|
The @code{return} command does not resume execution; it leaves the
|
|
program stopped in the state that would exist if the function had just
|
|
returned. In contrast, the @code{finish} command (@pxref{Continuing
|
|
and Stepping, ,Continuing and Stepping}) resumes execution until the
|
|
selected stack frame returns naturally.
|
|
|
|
@value{GDBN} needs to know how the @var{expression} argument should be set for
|
|
the inferior. The concrete registers assignment depends on the OS ABI and the
|
|
type being returned by the selected stack frame. For example it is common for
|
|
OS ABI to return floating point values in FPU registers while integer values in
|
|
CPU registers. Still some ABIs return even floating point values in CPU
|
|
registers. Larger integer widths (such as @code{long long int}) also have
|
|
specific placement rules. @value{GDBN} already knows the OS ABI from its
|
|
current target so it needs to find out also the type being returned to make the
|
|
assignment into the right register(s).
|
|
|
|
Normally, the selected stack frame has debug info. @value{GDBN} will always
|
|
use the debug info instead of the implicit type of @var{expression} when the
|
|
debug info is available. For example, if you type @kbd{return -1}, and the
|
|
function in the current stack frame is declared to return a @code{long long
|
|
int}, @value{GDBN} transparently converts the implicit @code{int} value of -1
|
|
into a @code{long long int}:
|
|
|
|
@smallexample
|
|
Breakpoint 1, func () at gdb.base/return-nodebug.c:29
|
|
29 return 31;
|
|
(@value{GDBP}) return -1
|
|
Make func return now? (y or n) y
|
|
#0 0x004004f6 in main () at gdb.base/return-nodebug.c:43
|
|
43 printf ("result=%lld\n", func ());
|
|
(@value{GDBP})
|
|
@end smallexample
|
|
|
|
However, if the selected stack frame does not have a debug info, e.g., if the
|
|
function was compiled without debug info, @value{GDBN} has to find out the type
|
|
to return from user. Specifying a different type by mistake may set the value
|
|
in different inferior registers than the caller code expects. For example,
|
|
typing @kbd{return -1} with its implicit type @code{int} would set only a part
|
|
of a @code{long long int} result for a debug info less function (on 32-bit
|
|
architectures). Therefore the user is required to specify the return type by
|
|
an appropriate cast explicitly:
|
|
|
|
@smallexample
|
|
Breakpoint 2, 0x0040050b in func ()
|
|
(@value{GDBP}) return -1
|
|
Return value type not available for selected stack frame.
|
|
Please use an explicit cast of the value to return.
|
|
(@value{GDBP}) return (long long int) -1
|
|
Make selected stack frame return now? (y or n) y
|
|
#0 0x00400526 in main ()
|
|
(@value{GDBP})
|
|
@end smallexample
|
|
|
|
@node Calling
|
|
@section Calling Program Functions
|
|
|
|
@table @code
|
|
@cindex calling functions
|
|
@cindex inferior functions, calling
|
|
@item print @var{expr}
|
|
Evaluate the expression @var{expr} and display the resulting value.
|
|
@var{expr} may include calls to functions in the program being
|
|
debugged.
|
|
|
|
@kindex call
|
|
@item call @var{expr}
|
|
Evaluate the expression @var{expr} without displaying @code{void}
|
|
returned values.
|
|
|
|
You can use this variant of the @code{print} command if you want to
|
|
execute a function from your program that does not return anything
|
|
(a.k.a.@: @dfn{a void function}), but without cluttering the output
|
|
with @code{void} returned values that @value{GDBN} will otherwise
|
|
print. If the result is not void, it is printed and saved in the
|
|
value history.
|
|
@end table
|
|
|
|
It is possible for the function you call via the @code{print} or
|
|
@code{call} command to generate a signal (e.g., if there's a bug in
|
|
the function, or if you passed it incorrect arguments). What happens
|
|
in that case is controlled by the @code{set unwindonsignal} command.
|
|
|
|
Similarly, with a C@t{++} program it is possible for the function you
|
|
call via the @code{print} or @code{call} command to generate an
|
|
exception that is not handled due to the constraints of the dummy
|
|
frame. In this case, any exception that is raised in the frame, but has
|
|
an out-of-frame exception handler will not be found. GDB builds a
|
|
dummy-frame for the inferior function call, and the unwinder cannot
|
|
seek for exception handlers outside of this dummy-frame. What happens
|
|
in that case is controlled by the
|
|
@code{set unwind-on-terminating-exception} command.
|
|
|
|
@table @code
|
|
@item set unwindonsignal
|
|
@kindex set unwindonsignal
|
|
@cindex unwind stack in called functions
|
|
@cindex call dummy stack unwinding
|
|
Set unwinding of the stack if a signal is received while in a function
|
|
that @value{GDBN} called in the program being debugged. If set to on,
|
|
@value{GDBN} unwinds the stack it created for the call and restores
|
|
the context to what it was before the call. If set to off (the
|
|
default), @value{GDBN} stops in the frame where the signal was
|
|
received.
|
|
|
|
@item show unwindonsignal
|
|
@kindex show unwindonsignal
|
|
Show the current setting of stack unwinding in the functions called by
|
|
@value{GDBN}.
|
|
|
|
@item set unwind-on-terminating-exception
|
|
@kindex set unwind-on-terminating-exception
|
|
@cindex unwind stack in called functions with unhandled exceptions
|
|
@cindex call dummy stack unwinding on unhandled exception.
|
|
Set unwinding of the stack if a C@t{++} exception is raised, but left
|
|
unhandled while in a function that @value{GDBN} called in the program being
|
|
debugged. If set to on (the default), @value{GDBN} unwinds the stack
|
|
it created for the call and restores the context to what it was before
|
|
the call. If set to off, @value{GDBN} the exception is delivered to
|
|
the default C@t{++} exception handler and the inferior terminated.
|
|
|
|
@item show unwind-on-terminating-exception
|
|
@kindex show unwind-on-terminating-exception
|
|
Show the current setting of stack unwinding in the functions called by
|
|
@value{GDBN}.
|
|
|
|
@end table
|
|
|
|
@cindex weak alias functions
|
|
Sometimes, a function you wish to call is actually a @dfn{weak alias}
|
|
for another function. In such case, @value{GDBN} might not pick up
|
|
the type information, including the types of the function arguments,
|
|
which causes @value{GDBN} to call the inferior function incorrectly.
|
|
As a result, the called function will function erroneously and may
|
|
even crash. A solution to that is to use the name of the aliased
|
|
function instead.
|
|
|
|
@node Patching
|
|
@section Patching Programs
|
|
|
|
@cindex patching binaries
|
|
@cindex writing into executables
|
|
@cindex writing into corefiles
|
|
|
|
By default, @value{GDBN} opens the file containing your program's
|
|
executable code (or the corefile) read-only. This prevents accidental
|
|
alterations to machine code; but it also prevents you from intentionally
|
|
patching your program's binary.
|
|
|
|
If you'd like to be able to patch the binary, you can specify that
|
|
explicitly with the @code{set write} command. For example, you might
|
|
want to turn on internal debugging flags, or even to make emergency
|
|
repairs.
|
|
|
|
@table @code
|
|
@kindex set write
|
|
@item set write on
|
|
@itemx set write off
|
|
If you specify @samp{set write on}, @value{GDBN} opens executable and
|
|
core files for both reading and writing; if you specify @kbd{set write
|
|
off} (the default), @value{GDBN} opens them read-only.
|
|
|
|
If you have already loaded a file, you must load it again (using the
|
|
@code{exec-file} or @code{core-file} command) after changing @code{set
|
|
write}, for your new setting to take effect.
|
|
|
|
@item show write
|
|
@kindex show write
|
|
Display whether executable files and core files are opened for writing
|
|
as well as reading.
|
|
@end table
|
|
|
|
@node GDB Files
|
|
@chapter @value{GDBN} Files
|
|
|
|
@value{GDBN} needs to know the file name of the program to be debugged,
|
|
both in order to read its symbol table and in order to start your
|
|
program. To debug a core dump of a previous run, you must also tell
|
|
@value{GDBN} the name of the core dump file.
|
|
|
|
@menu
|
|
* Files:: Commands to specify files
|
|
* Separate Debug Files:: Debugging information in separate files
|
|
* Index Files:: Index files speed up GDB
|
|
* Symbol Errors:: Errors reading symbol files
|
|
* Data Files:: GDB data files
|
|
@end menu
|
|
|
|
@node Files
|
|
@section Commands to Specify Files
|
|
|
|
@cindex symbol table
|
|
@cindex core dump file
|
|
|
|
You may want to specify executable and core dump file names. The usual
|
|
way to do this is at start-up time, using the arguments to
|
|
@value{GDBN}'s start-up commands (@pxref{Invocation, , Getting In and
|
|
Out of @value{GDBN}}).
|
|
|
|
Occasionally it is necessary to change to a different file during a
|
|
@value{GDBN} session. Or you may run @value{GDBN} and forget to
|
|
specify a file you want to use. Or you are debugging a remote target
|
|
via @code{gdbserver} (@pxref{Server, file, Using the @code{gdbserver}
|
|
Program}). In these situations the @value{GDBN} commands to specify
|
|
new files are useful.
|
|
|
|
@table @code
|
|
@cindex executable file
|
|
@kindex file
|
|
@item file @var{filename}
|
|
Use @var{filename} as the program to be debugged. It is read for its
|
|
symbols and for the contents of pure memory. It is also the program
|
|
executed when you use the @code{run} command. If you do not specify a
|
|
directory and the file is not found in the @value{GDBN} working directory,
|
|
@value{GDBN} uses the environment variable @code{PATH} as a list of
|
|
directories to search, just as the shell does when looking for a program
|
|
to run. You can change the value of this variable, for both @value{GDBN}
|
|
and your program, using the @code{path} command.
|
|
|
|
@cindex unlinked object files
|
|
@cindex patching object files
|
|
You can load unlinked object @file{.o} files into @value{GDBN} using
|
|
the @code{file} command. You will not be able to ``run'' an object
|
|
file, but you can disassemble functions and inspect variables. Also,
|
|
if the underlying BFD functionality supports it, you could use
|
|
@kbd{gdb -write} to patch object files using this technique. Note
|
|
that @value{GDBN} can neither interpret nor modify relocations in this
|
|
case, so branches and some initialized variables will appear to go to
|
|
the wrong place. But this feature is still handy from time to time.
|
|
|
|
@item file
|
|
@code{file} with no argument makes @value{GDBN} discard any information it
|
|
has on both executable file and the symbol table.
|
|
|
|
@kindex exec-file
|
|
@item exec-file @r{[} @var{filename} @r{]}
|
|
Specify that the program to be run (but not the symbol table) is found
|
|
in @var{filename}. @value{GDBN} searches the environment variable @code{PATH}
|
|
if necessary to locate your program. Omitting @var{filename} means to
|
|
discard information on the executable file.
|
|
|
|
@kindex symbol-file
|
|
@item symbol-file @r{[} @var{filename} @r{]}
|
|
Read symbol table information from file @var{filename}. @code{PATH} is
|
|
searched when necessary. Use the @code{file} command to get both symbol
|
|
table and program to run from the same file.
|
|
|
|
@code{symbol-file} with no argument clears out @value{GDBN} information on your
|
|
program's symbol table.
|
|
|
|
The @code{symbol-file} command causes @value{GDBN} to forget the contents of
|
|
some breakpoints and auto-display expressions. This is because they may
|
|
contain pointers to the internal data recording symbols and data types,
|
|
which are part of the old symbol table data being discarded inside
|
|
@value{GDBN}.
|
|
|
|
@code{symbol-file} does not repeat if you press @key{RET} again after
|
|
executing it once.
|
|
|
|
When @value{GDBN} is configured for a particular environment, it
|
|
understands debugging information in whatever format is the standard
|
|
generated for that environment; you may use either a @sc{gnu} compiler, or
|
|
other compilers that adhere to the local conventions.
|
|
Best results are usually obtained from @sc{gnu} compilers; for example,
|
|
using @code{@value{NGCC}} you can generate debugging information for
|
|
optimized code.
|
|
|
|
For most kinds of object files, with the exception of old SVR3 systems
|
|
using COFF, the @code{symbol-file} command does not normally read the
|
|
symbol table in full right away. Instead, it scans the symbol table
|
|
quickly to find which source files and which symbols are present. The
|
|
details are read later, one source file at a time, as they are needed.
|
|
|
|
The purpose of this two-stage reading strategy is to make @value{GDBN}
|
|
start up faster. For the most part, it is invisible except for
|
|
occasional pauses while the symbol table details for a particular source
|
|
file are being read. (The @code{set verbose} command can turn these
|
|
pauses into messages if desired. @xref{Messages/Warnings, ,Optional
|
|
Warnings and Messages}.)
|
|
|
|
We have not implemented the two-stage strategy for COFF yet. When the
|
|
symbol table is stored in COFF format, @code{symbol-file} reads the
|
|
symbol table data in full right away. Note that ``stabs-in-COFF''
|
|
still does the two-stage strategy, since the debug info is actually
|
|
in stabs format.
|
|
|
|
@kindex readnow
|
|
@cindex reading symbols immediately
|
|
@cindex symbols, reading immediately
|
|
@item symbol-file @r{[} -readnow @r{]} @var{filename}
|
|
@itemx file @r{[} -readnow @r{]} @var{filename}
|
|
You can override the @value{GDBN} two-stage strategy for reading symbol
|
|
tables by using the @samp{-readnow} option with any of the commands that
|
|
load symbol table information, if you want to be sure @value{GDBN} has the
|
|
entire symbol table available.
|
|
|
|
@c FIXME: for now no mention of directories, since this seems to be in
|
|
@c flux. 13mar1992 status is that in theory GDB would look either in
|
|
@c current dir or in same dir as myprog; but issues like competing
|
|
@c GDB's, or clutter in system dirs, mean that in practice right now
|
|
@c only current dir is used. FFish says maybe a special GDB hierarchy
|
|
@c (eg rooted in val of env var GDBSYMS) could exist for mappable symbol
|
|
@c files.
|
|
|
|
@kindex core-file
|
|
@item core-file @r{[}@var{filename}@r{]}
|
|
@itemx core
|
|
Specify the whereabouts of a core dump file to be used as the ``contents
|
|
of memory''. Traditionally, core files contain only some parts of the
|
|
address space of the process that generated them; @value{GDBN} can access the
|
|
executable file itself for other parts.
|
|
|
|
@code{core-file} with no argument specifies that no core file is
|
|
to be used.
|
|
|
|
Note that the core file is ignored when your program is actually running
|
|
under @value{GDBN}. So, if you have been running your program and you
|
|
wish to debug a core file instead, you must kill the subprocess in which
|
|
the program is running. To do this, use the @code{kill} command
|
|
(@pxref{Kill Process, ,Killing the Child Process}).
|
|
|
|
@kindex add-symbol-file
|
|
@cindex dynamic linking
|
|
@item add-symbol-file @var{filename} @var{address}
|
|
@itemx add-symbol-file @var{filename} @var{address} @r{[} -readnow @r{]}
|
|
@itemx add-symbol-file @var{filename} @var{address} -s @var{section} @var{address} @dots{}
|
|
The @code{add-symbol-file} command reads additional symbol table
|
|
information from the file @var{filename}. You would use this command
|
|
when @var{filename} has been dynamically loaded (by some other means)
|
|
into the program that is running. @var{address} should be the memory
|
|
address at which the file has been loaded; @value{GDBN} cannot figure
|
|
this out for itself. You can additionally specify an arbitrary number
|
|
of @samp{-s @var{section} @var{address}} pairs, to give an explicit
|
|
section name and base address for that section. You can specify any
|
|
@var{address} as an expression.
|
|
|
|
The symbol table of the file @var{filename} is added to the symbol table
|
|
originally read with the @code{symbol-file} command. You can use the
|
|
@code{add-symbol-file} command any number of times; the new symbol data
|
|
thus read keeps adding to the old. To discard all old symbol data
|
|
instead, use the @code{symbol-file} command without any arguments.
|
|
|
|
@cindex relocatable object files, reading symbols from
|
|
@cindex object files, relocatable, reading symbols from
|
|
@cindex reading symbols from relocatable object files
|
|
@cindex symbols, reading from relocatable object files
|
|
@cindex @file{.o} files, reading symbols from
|
|
Although @var{filename} is typically a shared library file, an
|
|
executable file, or some other object file which has been fully
|
|
relocated for loading into a process, you can also load symbolic
|
|
information from relocatable @file{.o} files, as long as:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
the file's symbolic information refers only to linker symbols defined in
|
|
that file, not to symbols defined by other object files,
|
|
@item
|
|
every section the file's symbolic information refers to has actually
|
|
been loaded into the inferior, as it appears in the file, and
|
|
@item
|
|
you can determine the address at which every section was loaded, and
|
|
provide these to the @code{add-symbol-file} command.
|
|
@end itemize
|
|
|
|
@noindent
|
|
Some embedded operating systems, like Sun Chorus and VxWorks, can load
|
|
relocatable files into an already running program; such systems
|
|
typically make the requirements above easy to meet. However, it's
|
|
important to recognize that many native systems use complex link
|
|
procedures (@code{.linkonce} section factoring and C@t{++} constructor table
|
|
assembly, for example) that make the requirements difficult to meet. In
|
|
general, one cannot assume that using @code{add-symbol-file} to read a
|
|
relocatable object file's symbolic information will have the same effect
|
|
as linking the relocatable object file into the program in the normal
|
|
way.
|
|
|
|
@code{add-symbol-file} does not repeat if you press @key{RET} after using it.
|
|
|
|
@kindex add-symbol-file-from-memory
|
|
@cindex @code{syscall DSO}
|
|
@cindex load symbols from memory
|
|
@item add-symbol-file-from-memory @var{address}
|
|
Load symbols from the given @var{address} in a dynamically loaded
|
|
object file whose image is mapped directly into the inferior's memory.
|
|
For example, the Linux kernel maps a @code{syscall DSO} into each
|
|
process's address space; this DSO provides kernel-specific code for
|
|
some system calls. The argument can be any expression whose
|
|
evaluation yields the address of the file's shared object file header.
|
|
For this command to work, you must have used @code{symbol-file} or
|
|
@code{exec-file} commands in advance.
|
|
|
|
@kindex add-shared-symbol-files
|
|
@kindex assf
|
|
@item add-shared-symbol-files @var{library-file}
|
|
@itemx assf @var{library-file}
|
|
The @code{add-shared-symbol-files} command can currently be used only
|
|
in the Cygwin build of @value{GDBN} on MS-Windows OS, where it is an
|
|
alias for the @code{dll-symbols} command (@pxref{Cygwin Native}).
|
|
@value{GDBN} automatically looks for shared libraries, however if
|
|
@value{GDBN} does not find yours, you can invoke
|
|
@code{add-shared-symbol-files}. It takes one argument: the shared
|
|
library's file name. @code{assf} is a shorthand alias for
|
|
@code{add-shared-symbol-files}.
|
|
|
|
@kindex section
|
|
@item section @var{section} @var{addr}
|
|
The @code{section} command changes the base address of the named
|
|
@var{section} of the exec file to @var{addr}. This can be used if the
|
|
exec file does not contain section addresses, (such as in the
|
|
@code{a.out} format), or when the addresses specified in the file
|
|
itself are wrong. Each section must be changed separately. The
|
|
@code{info files} command, described below, lists all the sections and
|
|
their addresses.
|
|
|
|
@kindex info files
|
|
@kindex info target
|
|
@item info files
|
|
@itemx info target
|
|
@code{info files} and @code{info target} are synonymous; both print the
|
|
current target (@pxref{Targets, ,Specifying a Debugging Target}),
|
|
including the names of the executable and core dump files currently in
|
|
use by @value{GDBN}, and the files from which symbols were loaded. The
|
|
command @code{help target} lists all possible targets rather than
|
|
current ones.
|
|
|
|
@kindex maint info sections
|
|
@item maint info sections
|
|
Another command that can give you extra information about program sections
|
|
is @code{maint info sections}. In addition to the section information
|
|
displayed by @code{info files}, this command displays the flags and file
|
|
offset of each section in the executable and core dump files. In addition,
|
|
@code{maint info sections} provides the following command options (which
|
|
may be arbitrarily combined):
|
|
|
|
@table @code
|
|
@item ALLOBJ
|
|
Display sections for all loaded object files, including shared libraries.
|
|
@item @var{sections}
|
|
Display info only for named @var{sections}.
|
|
@item @var{section-flags}
|
|
Display info only for sections for which @var{section-flags} are true.
|
|
The section flags that @value{GDBN} currently knows about are:
|
|
@table @code
|
|
@item ALLOC
|
|
Section will have space allocated in the process when loaded.
|
|
Set for all sections except those containing debug information.
|
|
@item LOAD
|
|
Section will be loaded from the file into the child process memory.
|
|
Set for pre-initialized code and data, clear for @code{.bss} sections.
|
|
@item RELOC
|
|
Section needs to be relocated before loading.
|
|
@item READONLY
|
|
Section cannot be modified by the child process.
|
|
@item CODE
|
|
Section contains executable code only.
|
|
@item DATA
|
|
Section contains data only (no executable code).
|
|
@item ROM
|
|
Section will reside in ROM.
|
|
@item CONSTRUCTOR
|
|
Section contains data for constructor/destructor lists.
|
|
@item HAS_CONTENTS
|
|
Section is not empty.
|
|
@item NEVER_LOAD
|
|
An instruction to the linker to not output the section.
|
|
@item COFF_SHARED_LIBRARY
|
|
A notification to the linker that the section contains
|
|
COFF shared library information.
|
|
@item IS_COMMON
|
|
Section contains common symbols.
|
|
@end table
|
|
@end table
|
|
@kindex set trust-readonly-sections
|
|
@cindex read-only sections
|
|
@item set trust-readonly-sections on
|
|
Tell @value{GDBN} that readonly sections in your object file
|
|
really are read-only (i.e.@: that their contents will not change).
|
|
In that case, @value{GDBN} can fetch values from these sections
|
|
out of the object file, rather than from the target program.
|
|
For some targets (notably embedded ones), this can be a significant
|
|
enhancement to debugging performance.
|
|
|
|
The default is off.
|
|
|
|
@item set trust-readonly-sections off
|
|
Tell @value{GDBN} not to trust readonly sections. This means that
|
|
the contents of the section might change while the program is running,
|
|
and must therefore be fetched from the target when needed.
|
|
|
|
@item show trust-readonly-sections
|
|
Show the current setting of trusting readonly sections.
|
|
@end table
|
|
|
|
All file-specifying commands allow both absolute and relative file names
|
|
as arguments. @value{GDBN} always converts the file name to an absolute file
|
|
name and remembers it that way.
|
|
|
|
@cindex shared libraries
|
|
@anchor{Shared Libraries}
|
|
@value{GDBN} supports @sc{gnu}/Linux, MS-Windows, HP-UX, SunOS, SVr4, Irix,
|
|
and IBM RS/6000 AIX shared libraries.
|
|
|
|
On MS-Windows @value{GDBN} must be linked with the Expat library to support
|
|
shared libraries. @xref{Expat}.
|
|
|
|
@value{GDBN} automatically loads symbol definitions from shared libraries
|
|
when you use the @code{run} command, or when you examine a core file.
|
|
(Before you issue the @code{run} command, @value{GDBN} does not understand
|
|
references to a function in a shared library, however---unless you are
|
|
debugging a core file).
|
|
|
|
On HP-UX, if the program loads a library explicitly, @value{GDBN}
|
|
automatically loads the symbols at the time of the @code{shl_load} call.
|
|
|
|
@c FIXME: some @value{GDBN} release may permit some refs to undef
|
|
@c FIXME...symbols---eg in a break cmd---assuming they are from a shared
|
|
@c FIXME...lib; check this from time to time when updating manual
|
|
|
|
There are times, however, when you may wish to not automatically load
|
|
symbol definitions from shared libraries, such as when they are
|
|
particularly large or there are many of them.
|
|
|
|
To control the automatic loading of shared library symbols, use the
|
|
commands:
|
|
|
|
@table @code
|
|
@kindex set auto-solib-add
|
|
@item set auto-solib-add @var{mode}
|
|
If @var{mode} is @code{on}, symbols from all shared object libraries
|
|
will be loaded automatically when the inferior begins execution, you
|
|
attach to an independently started inferior, or when the dynamic linker
|
|
informs @value{GDBN} that a new library has been loaded. If @var{mode}
|
|
is @code{off}, symbols must be loaded manually, using the
|
|
@code{sharedlibrary} command. The default value is @code{on}.
|
|
|
|
@cindex memory used for symbol tables
|
|
If your program uses lots of shared libraries with debug info that
|
|
takes large amounts of memory, you can decrease the @value{GDBN}
|
|
memory footprint by preventing it from automatically loading the
|
|
symbols from shared libraries. To that end, type @kbd{set
|
|
auto-solib-add off} before running the inferior, then load each
|
|
library whose debug symbols you do need with @kbd{sharedlibrary
|
|
@var{regexp}}, where @var{regexp} is a regular expression that matches
|
|
the libraries whose symbols you want to be loaded.
|
|
|
|
@kindex show auto-solib-add
|
|
@item show auto-solib-add
|
|
Display the current autoloading mode.
|
|
@end table
|
|
|
|
@cindex load shared library
|
|
To explicitly load shared library symbols, use the @code{sharedlibrary}
|
|
command:
|
|
|
|
@table @code
|
|
@kindex info sharedlibrary
|
|
@kindex info share
|
|
@item info share @var{regex}
|
|
@itemx info sharedlibrary @var{regex}
|
|
Print the names of the shared libraries which are currently loaded
|
|
that match @var{regex}. If @var{regex} is omitted then print
|
|
all shared libraries that are loaded.
|
|
|
|
@kindex sharedlibrary
|
|
@kindex share
|
|
@item sharedlibrary @var{regex}
|
|
@itemx share @var{regex}
|
|
Load shared object library symbols for files matching a
|
|
Unix regular expression.
|
|
As with files loaded automatically, it only loads shared libraries
|
|
required by your program for a core file or after typing @code{run}. If
|
|
@var{regex} is omitted all shared libraries required by your program are
|
|
loaded.
|
|
|
|
@item nosharedlibrary
|
|
@kindex nosharedlibrary
|
|
@cindex unload symbols from shared libraries
|
|
Unload all shared object library symbols. This discards all symbols
|
|
that have been loaded from all shared libraries. Symbols from shared
|
|
libraries that were loaded by explicit user requests are not
|
|
discarded.
|
|
@end table
|
|
|
|
Sometimes you may wish that @value{GDBN} stops and gives you control
|
|
when any of shared library events happen. The best way to do this is
|
|
to use @code{catch load} and @code{catch unload} (@pxref{Set
|
|
Catchpoints}).
|
|
|
|
@value{GDBN} also supports the the @code{set stop-on-solib-events}
|
|
command for this. This command exists for historical reasons. It is
|
|
less useful than setting a catchpoint, because it does not allow for
|
|
conditions or commands as a catchpoint does.
|
|
|
|
@table @code
|
|
@item set stop-on-solib-events
|
|
@kindex set stop-on-solib-events
|
|
This command controls whether @value{GDBN} should give you control
|
|
when the dynamic linker notifies it about some shared library event.
|
|
The most common event of interest is loading or unloading of a new
|
|
shared library.
|
|
|
|
@item show stop-on-solib-events
|
|
@kindex show stop-on-solib-events
|
|
Show whether @value{GDBN} stops and gives you control when shared
|
|
library events happen.
|
|
@end table
|
|
|
|
Shared libraries are also supported in many cross or remote debugging
|
|
configurations. @value{GDBN} needs to have access to the target's libraries;
|
|
this can be accomplished either by providing copies of the libraries
|
|
on the host system, or by asking @value{GDBN} to automatically retrieve the
|
|
libraries from the target. If copies of the target libraries are
|
|
provided, they need to be the same as the target libraries, although the
|
|
copies on the target can be stripped as long as the copies on the host are
|
|
not.
|
|
|
|
@cindex where to look for shared libraries
|
|
For remote debugging, you need to tell @value{GDBN} where the target
|
|
libraries are, so that it can load the correct copies---otherwise, it
|
|
may try to load the host's libraries. @value{GDBN} has two variables
|
|
to specify the search directories for target libraries.
|
|
|
|
@table @code
|
|
@cindex prefix for shared library file names
|
|
@cindex system root, alternate
|
|
@kindex set solib-absolute-prefix
|
|
@kindex set sysroot
|
|
@item set sysroot @var{path}
|
|
Use @var{path} as the system root for the program being debugged. Any
|
|
absolute shared library paths will be prefixed with @var{path}; many
|
|
runtime loaders store the absolute paths to the shared library in the
|
|
target program's memory. If you use @code{set sysroot} to find shared
|
|
libraries, they need to be laid out in the same way that they are on
|
|
the target, with e.g.@: a @file{/lib} and @file{/usr/lib} hierarchy
|
|
under @var{path}.
|
|
|
|
If @var{path} starts with the sequence @file{remote:}, @value{GDBN} will
|
|
retrieve the target libraries from the remote system. This is only
|
|
supported when using a remote target that supports the @code{remote get}
|
|
command (@pxref{File Transfer,,Sending files to a remote system}).
|
|
The part of @var{path} following the initial @file{remote:}
|
|
(if present) is used as system root prefix on the remote file system.
|
|
@footnote{If you want to specify a local system root using a directory
|
|
that happens to be named @file{remote:}, you need to use some equivalent
|
|
variant of the name like @file{./remote:}.}
|
|
|
|
For targets with an MS-DOS based filesystem, such as MS-Windows and
|
|
SymbianOS, @value{GDBN} tries prefixing a few variants of the target
|
|
absolute file name with @var{path}. But first, on Unix hosts,
|
|
@value{GDBN} converts all backslash directory separators into forward
|
|
slashes, because the backslash is not a directory separator on Unix:
|
|
|
|
@smallexample
|
|
c:\foo\bar.dll @result{} c:/foo/bar.dll
|
|
@end smallexample
|
|
|
|
Then, @value{GDBN} attempts prefixing the target file name with
|
|
@var{path}, and looks for the resulting file name in the host file
|
|
system:
|
|
|
|
@smallexample
|
|
c:/foo/bar.dll @result{} /path/to/sysroot/c:/foo/bar.dll
|
|
@end smallexample
|
|
|
|
If that does not find the shared library, @value{GDBN} tries removing
|
|
the @samp{:} character from the drive spec, both for convenience, and,
|
|
for the case of the host file system not supporting file names with
|
|
colons:
|
|
|
|
@smallexample
|
|
c:/foo/bar.dll @result{} /path/to/sysroot/c/foo/bar.dll
|
|
@end smallexample
|
|
|
|
This makes it possible to have a system root that mirrors a target
|
|
with more than one drive. E.g., you may want to setup your local
|
|
copies of the target system shared libraries like so (note @samp{c} vs
|
|
@samp{z}):
|
|
|
|
@smallexample
|
|
@file{/path/to/sysroot/c/sys/bin/foo.dll}
|
|
@file{/path/to/sysroot/c/sys/bin/bar.dll}
|
|
@file{/path/to/sysroot/z/sys/bin/bar.dll}
|
|
@end smallexample
|
|
|
|
@noindent
|
|
and point the system root at @file{/path/to/sysroot}, so that
|
|
@value{GDBN} can find the correct copies of both
|
|
@file{c:\sys\bin\foo.dll}, and @file{z:\sys\bin\bar.dll}.
|
|
|
|
If that still does not find the shared library, @value{GDBN} tries
|
|
removing the whole drive spec from the target file name:
|
|
|
|
@smallexample
|
|
c:/foo/bar.dll @result{} /path/to/sysroot/foo/bar.dll
|
|
@end smallexample
|
|
|
|
This last lookup makes it possible to not care about the drive name,
|
|
if you don't want or need to.
|
|
|
|
The @code{set solib-absolute-prefix} command is an alias for @code{set
|
|
sysroot}.
|
|
|
|
@cindex default system root
|
|
@cindex @samp{--with-sysroot}
|
|
You can set the default system root by using the configure-time
|
|
@samp{--with-sysroot} option. If the system root is inside
|
|
@value{GDBN}'s configured binary prefix (set with @samp{--prefix} or
|
|
@samp{--exec-prefix}), then the default system root will be updated
|
|
automatically if the installed @value{GDBN} is moved to a new
|
|
location.
|
|
|
|
@kindex show sysroot
|
|
@item show sysroot
|
|
Display the current shared library prefix.
|
|
|
|
@kindex set solib-search-path
|
|
@item set solib-search-path @var{path}
|
|
If this variable is set, @var{path} is a colon-separated list of
|
|
directories to search for shared libraries. @samp{solib-search-path}
|
|
is used after @samp{sysroot} fails to locate the library, or if the
|
|
path to the library is relative instead of absolute. If you want to
|
|
use @samp{solib-search-path} instead of @samp{sysroot}, be sure to set
|
|
@samp{sysroot} to a nonexistent directory to prevent @value{GDBN} from
|
|
finding your host's libraries. @samp{sysroot} is preferred; setting
|
|
it to a nonexistent directory may interfere with automatic loading
|
|
of shared library symbols.
|
|
|
|
@kindex show solib-search-path
|
|
@item show solib-search-path
|
|
Display the current shared library search path.
|
|
|
|
@cindex DOS file-name semantics of file names.
|
|
@kindex set target-file-system-kind (unix|dos-based|auto)
|
|
@kindex show target-file-system-kind
|
|
@item set target-file-system-kind @var{kind}
|
|
Set assumed file system kind for target reported file names.
|
|
|
|
Shared library file names as reported by the target system may not
|
|
make sense as is on the system @value{GDBN} is running on. For
|
|
example, when remote debugging a target that has MS-DOS based file
|
|
system semantics, from a Unix host, the target may be reporting to
|
|
@value{GDBN} a list of loaded shared libraries with file names such as
|
|
@file{c:\Windows\kernel32.dll}. On Unix hosts, there's no concept of
|
|
drive letters, so the @samp{c:\} prefix is not normally understood as
|
|
indicating an absolute file name, and neither is the backslash
|
|
normally considered a directory separator character. In that case,
|
|
the native file system would interpret this whole absolute file name
|
|
as a relative file name with no directory components. This would make
|
|
it impossible to point @value{GDBN} at a copy of the remote target's
|
|
shared libraries on the host using @code{set sysroot}, and impractical
|
|
with @code{set solib-search-path}. Setting
|
|
@code{target-file-system-kind} to @code{dos-based} tells @value{GDBN}
|
|
to interpret such file names similarly to how the target would, and to
|
|
map them to file names valid on @value{GDBN}'s native file system
|
|
semantics. The value of @var{kind} can be @code{"auto"}, in addition
|
|
to one of the supported file system kinds. In that case, @value{GDBN}
|
|
tries to determine the appropriate file system variant based on the
|
|
current target's operating system (@pxref{ABI, ,Configuring the
|
|
Current ABI}). The supported file system settings are:
|
|
|
|
@table @code
|
|
@item unix
|
|
Instruct @value{GDBN} to assume the target file system is of Unix
|
|
kind. Only file names starting the forward slash (@samp{/}) character
|
|
are considered absolute, and the directory separator character is also
|
|
the forward slash.
|
|
|
|
@item dos-based
|
|
Instruct @value{GDBN} to assume the target file system is DOS based.
|
|
File names starting with either a forward slash, or a drive letter
|
|
followed by a colon (e.g., @samp{c:}), are considered absolute, and
|
|
both the slash (@samp{/}) and the backslash (@samp{\\}) characters are
|
|
considered directory separators.
|
|
|
|
@item auto
|
|
Instruct @value{GDBN} to use the file system kind associated with the
|
|
target operating system (@pxref{ABI, ,Configuring the Current ABI}).
|
|
This is the default.
|
|
@end table
|
|
@end table
|
|
|
|
@cindex file name canonicalization
|
|
@cindex base name differences
|
|
When processing file names provided by the user, @value{GDBN}
|
|
frequently needs to compare them to the file names recorded in the
|
|
program's debug info. Normally, @value{GDBN} compares just the
|
|
@dfn{base names} of the files as strings, which is reasonably fast
|
|
even for very large programs. (The base name of a file is the last
|
|
portion of its name, after stripping all the leading directories.)
|
|
This shortcut in comparison is based upon the assumption that files
|
|
cannot have more than one base name. This is usually true, but
|
|
references to files that use symlinks or similar filesystem
|
|
facilities violate that assumption. If your program records files
|
|
using such facilities, or if you provide file names to @value{GDBN}
|
|
using symlinks etc., you can set @code{basenames-may-differ} to
|
|
@code{true} to instruct @value{GDBN} to completely canonicalize each
|
|
pair of file names it needs to compare. This will make file-name
|
|
comparisons accurate, but at a price of a significant slowdown.
|
|
|
|
@table @code
|
|
@item set basenames-may-differ
|
|
@kindex set basenames-may-differ
|
|
Set whether a source file may have multiple base names.
|
|
|
|
@item show basenames-may-differ
|
|
@kindex show basenames-may-differ
|
|
Show whether a source file may have multiple base names.
|
|
@end table
|
|
|
|
@node Separate Debug Files
|
|
@section Debugging Information in Separate Files
|
|
@cindex separate debugging information files
|
|
@cindex debugging information in separate files
|
|
@cindex @file{.debug} subdirectories
|
|
@cindex debugging information directory, global
|
|
@cindex global debugging information directories
|
|
@cindex build ID, and separate debugging files
|
|
@cindex @file{.build-id} directory
|
|
|
|
@value{GDBN} allows you to put a program's debugging information in a
|
|
file separate from the executable itself, in a way that allows
|
|
@value{GDBN} to find and load the debugging information automatically.
|
|
Since debugging information can be very large---sometimes larger
|
|
than the executable code itself---some systems distribute debugging
|
|
information for their executables in separate files, which users can
|
|
install only when they need to debug a problem.
|
|
|
|
@value{GDBN} supports two ways of specifying the separate debug info
|
|
file:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
The executable contains a @dfn{debug link} that specifies the name of
|
|
the separate debug info file. The separate debug file's name is
|
|
usually @file{@var{executable}.debug}, where @var{executable} is the
|
|
name of the corresponding executable file without leading directories
|
|
(e.g., @file{ls.debug} for @file{/usr/bin/ls}). In addition, the
|
|
debug link specifies a 32-bit @dfn{Cyclic Redundancy Check} (CRC)
|
|
checksum for the debug file, which @value{GDBN} uses to validate that
|
|
the executable and the debug file came from the same build.
|
|
|
|
@item
|
|
The executable contains a @dfn{build ID}, a unique bit string that is
|
|
also present in the corresponding debug info file. (This is supported
|
|
only on some operating systems, notably those which use the ELF format
|
|
for binary files and the @sc{gnu} Binutils.) For more details about
|
|
this feature, see the description of the @option{--build-id}
|
|
command-line option in @ref{Options, , Command Line Options, ld.info,
|
|
The GNU Linker}. The debug info file's name is not specified
|
|
explicitly by the build ID, but can be computed from the build ID, see
|
|
below.
|
|
@end itemize
|
|
|
|
Depending on the way the debug info file is specified, @value{GDBN}
|
|
uses two different methods of looking for the debug file:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
For the ``debug link'' method, @value{GDBN} looks up the named file in
|
|
the directory of the executable file, then in a subdirectory of that
|
|
directory named @file{.debug}, and finally under each one of the global debug
|
|
directories, in a subdirectory whose name is identical to the leading
|
|
directories of the executable's absolute file name.
|
|
|
|
@item
|
|
For the ``build ID'' method, @value{GDBN} looks in the
|
|
@file{.build-id} subdirectory of each one of the global debug directories for
|
|
a file named @file{@var{nn}/@var{nnnnnnnn}.debug}, where @var{nn} are the
|
|
first 2 hex characters of the build ID bit string, and @var{nnnnnnnn}
|
|
are the rest of the bit string. (Real build ID strings are 32 or more
|
|
hex characters, not 10.)
|
|
@end itemize
|
|
|
|
So, for example, suppose you ask @value{GDBN} to debug
|
|
@file{/usr/bin/ls}, which has a debug link that specifies the
|
|
file @file{ls.debug}, and a build ID whose value in hex is
|
|
@code{abcdef1234}. If the list of the global debug directories includes
|
|
@file{/usr/lib/debug}, then @value{GDBN} will look for the following
|
|
debug information files, in the indicated order:
|
|
|
|
@itemize @minus
|
|
@item
|
|
@file{/usr/lib/debug/.build-id/ab/cdef1234.debug}
|
|
@item
|
|
@file{/usr/bin/ls.debug}
|
|
@item
|
|
@file{/usr/bin/.debug/ls.debug}
|
|
@item
|
|
@file{/usr/lib/debug/usr/bin/ls.debug}.
|
|
@end itemize
|
|
|
|
@anchor{debug-file-directory}
|
|
Global debugging info directories default to what is set by @value{GDBN}
|
|
configure option @option{--with-separate-debug-dir}. During @value{GDBN} run
|
|
you can also set the global debugging info directories, and view the list
|
|
@value{GDBN} is currently using.
|
|
|
|
@table @code
|
|
|
|
@kindex set debug-file-directory
|
|
@item set debug-file-directory @var{directories}
|
|
Set the directories which @value{GDBN} searches for separate debugging
|
|
information files to @var{directory}. Multiple path components can be set
|
|
concatenating them by a path separator.
|
|
|
|
@kindex show debug-file-directory
|
|
@item show debug-file-directory
|
|
Show the directories @value{GDBN} searches for separate debugging
|
|
information files.
|
|
|
|
@end table
|
|
|
|
@cindex @code{.gnu_debuglink} sections
|
|
@cindex debug link sections
|
|
A debug link is a special section of the executable file named
|
|
@code{.gnu_debuglink}. The section must contain:
|
|
|
|
@itemize
|
|
@item
|
|
A filename, with any leading directory components removed, followed by
|
|
a zero byte,
|
|
@item
|
|
zero to three bytes of padding, as needed to reach the next four-byte
|
|
boundary within the section, and
|
|
@item
|
|
a four-byte CRC checksum, stored in the same endianness used for the
|
|
executable file itself. The checksum is computed on the debugging
|
|
information file's full contents by the function given below, passing
|
|
zero as the @var{crc} argument.
|
|
@end itemize
|
|
|
|
Any executable file format can carry a debug link, as long as it can
|
|
contain a section named @code{.gnu_debuglink} with the contents
|
|
described above.
|
|
|
|
@cindex @code{.note.gnu.build-id} sections
|
|
@cindex build ID sections
|
|
The build ID is a special section in the executable file (and in other
|
|
ELF binary files that @value{GDBN} may consider). This section is
|
|
often named @code{.note.gnu.build-id}, but that name is not mandatory.
|
|
It contains unique identification for the built files---the ID remains
|
|
the same across multiple builds of the same build tree. The default
|
|
algorithm SHA1 produces 160 bits (40 hexadecimal characters) of the
|
|
content for the build ID string. The same section with an identical
|
|
value is present in the original built binary with symbols, in its
|
|
stripped variant, and in the separate debugging information file.
|
|
|
|
The debugging information file itself should be an ordinary
|
|
executable, containing a full set of linker symbols, sections, and
|
|
debugging information. The sections of the debugging information file
|
|
should have the same names, addresses, and sizes as the original file,
|
|
but they need not contain any data---much like a @code{.bss} section
|
|
in an ordinary executable.
|
|
|
|
The @sc{gnu} binary utilities (Binutils) package includes the
|
|
@samp{objcopy} utility that can produce
|
|
the separated executable / debugging information file pairs using the
|
|
following commands:
|
|
|
|
@smallexample
|
|
@kbd{objcopy --only-keep-debug foo foo.debug}
|
|
@kbd{strip -g foo}
|
|
@end smallexample
|
|
|
|
@noindent
|
|
These commands remove the debugging
|
|
information from the executable file @file{foo} and place it in the file
|
|
@file{foo.debug}. You can use the first, second or both methods to link the
|
|
two files:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
The debug link method needs the following additional command to also leave
|
|
behind a debug link in @file{foo}:
|
|
|
|
@smallexample
|
|
@kbd{objcopy --add-gnu-debuglink=foo.debug foo}
|
|
@end smallexample
|
|
|
|
Ulrich Drepper's @file{elfutils} package, starting with version 0.53, contains
|
|
a version of the @code{strip} command such that the command @kbd{strip foo -f
|
|
foo.debug} has the same functionality as the two @code{objcopy} commands and
|
|
the @code{ln -s} command above, together.
|
|
|
|
@item
|
|
Build ID gets embedded into the main executable using @code{ld --build-id} or
|
|
the @value{NGCC} counterpart @code{gcc -Wl,--build-id}. Build ID support plus
|
|
compatibility fixes for debug files separation are present in @sc{gnu} binary
|
|
utilities (Binutils) package since version 2.18.
|
|
@end itemize
|
|
|
|
@noindent
|
|
|
|
@cindex CRC algorithm definition
|
|
The CRC used in @code{.gnu_debuglink} is the CRC-32 defined in
|
|
IEEE 802.3 using the polynomial:
|
|
|
|
@c TexInfo requires naked braces for multi-digit exponents for Tex
|
|
@c output, but this causes HTML output to barf. HTML has to be set using
|
|
@c raw commands. So we end up having to specify this equation in 2
|
|
@c different ways!
|
|
@ifhtml
|
|
@display
|
|
@html
|
|
<em>x</em><sup>32</sup> + <em>x</em><sup>26</sup> + <em>x</em><sup>23</sup> + <em>x</em><sup>22</sup> + <em>x</em><sup>16</sup> + <em>x</em><sup>12</sup> + <em>x</em><sup>11</sup>
|
|
+ <em>x</em><sup>10</sup> + <em>x</em><sup>8</sup> + <em>x</em><sup>7</sup> + <em>x</em><sup>5</sup> + <em>x</em><sup>4</sup> + <em>x</em><sup>2</sup> + <em>x</em> + 1
|
|
@end html
|
|
@end display
|
|
@end ifhtml
|
|
@ifnothtml
|
|
@display
|
|
@math{x^{32} + x^{26} + x^{23} + x^{22} + x^{16} + x^{12} + x^{11}}
|
|
@math{+ x^{10} + x^8 + x^7 + x^5 + x^4 + x^2 + x + 1}
|
|
@end display
|
|
@end ifnothtml
|
|
|
|
The function is computed byte at a time, taking the least
|
|
significant bit of each byte first. The initial pattern
|
|
@code{0xffffffff} is used, to ensure leading zeros affect the CRC and
|
|
the final result is inverted to ensure trailing zeros also affect the
|
|
CRC.
|
|
|
|
@emph{Note:} This is the same CRC polynomial as used in handling the
|
|
@dfn{Remote Serial Protocol} @code{qCRC} packet (@pxref{Remote Protocol,
|
|
, @value{GDBN} Remote Serial Protocol}). However in the
|
|
case of the Remote Serial Protocol, the CRC is computed @emph{most}
|
|
significant bit first, and the result is not inverted, so trailing
|
|
zeros have no effect on the CRC value.
|
|
|
|
To complete the description, we show below the code of the function
|
|
which produces the CRC used in @code{.gnu_debuglink}. Inverting the
|
|
initially supplied @code{crc} argument means that an initial call to
|
|
this function passing in zero will start computing the CRC using
|
|
@code{0xffffffff}.
|
|
|
|
@kindex gnu_debuglink_crc32
|
|
@smallexample
|
|
unsigned long
|
|
gnu_debuglink_crc32 (unsigned long crc,
|
|
unsigned char *buf, size_t len)
|
|
@{
|
|
static const unsigned long crc32_table[256] =
|
|
@{
|
|
0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419,
|
|
0x706af48f, 0xe963a535, 0x9e6495a3, 0x0edb8832, 0x79dcb8a4,
|
|
0xe0d5e91e, 0x97d2d988, 0x09b64c2b, 0x7eb17cbd, 0xe7b82d07,
|
|
0x90bf1d91, 0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de,
|
|
0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7, 0x136c9856,
|
|
0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9,
|
|
0xfa0f3d63, 0x8d080df5, 0x3b6e20c8, 0x4c69105e, 0xd56041e4,
|
|
0xa2677172, 0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b,
|
|
0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940, 0x32d86ce3,
|
|
0x45df5c75, 0xdcd60dcf, 0xabd13d59, 0x26d930ac, 0x51de003a,
|
|
0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423, 0xcfba9599,
|
|
0xb8bda50f, 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924,
|
|
0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d, 0x76dc4190,
|
|
0x01db7106, 0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f,
|
|
0x9fbfe4a5, 0xe8b8d433, 0x7807c9a2, 0x0f00f934, 0x9609a88e,
|
|
0xe10e9818, 0x7f6a0dbb, 0x086d3d2d, 0x91646c97, 0xe6635c01,
|
|
0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e, 0x6c0695ed,
|
|
0x1b01a57b, 0x8208f4c1, 0xf50fc457, 0x65b0d9c6, 0x12b7e950,
|
|
0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3,
|
|
0xfbd44c65, 0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2,
|
|
0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb, 0x4369e96a,
|
|
0x346ed9fc, 0xad678846, 0xda60b8d0, 0x44042d73, 0x33031de5,
|
|
0xaa0a4c5f, 0xdd0d7cc9, 0x5005713c, 0x270241aa, 0xbe0b1010,
|
|
0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
|
|
0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17,
|
|
0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad, 0xedb88320, 0x9abfb3b6,
|
|
0x03b6e20c, 0x74b1d29a, 0xead54739, 0x9dd277af, 0x04db2615,
|
|
0x73dc1683, 0xe3630b12, 0x94643b84, 0x0d6d6a3e, 0x7a6a5aa8,
|
|
0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1, 0xf00f9344,
|
|
0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb,
|
|
0x196c3671, 0x6e6b06e7, 0xfed41b76, 0x89d32be0, 0x10da7a5a,
|
|
0x67dd4acc, 0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5,
|
|
0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252, 0xd1bb67f1,
|
|
0xa6bc5767, 0x3fb506dd, 0x48b2364b, 0xd80d2bda, 0xaf0a1b4c,
|
|
0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55, 0x316e8eef,
|
|
0x4669be79, 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236,
|
|
0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, 0xc5ba3bbe,
|
|
0xb2bd0b28, 0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31,
|
|
0x2cd99e8b, 0x5bdeae1d, 0x9b64c2b0, 0xec63f226, 0x756aa39c,
|
|
0x026d930a, 0x9c0906a9, 0xeb0e363f, 0x72076785, 0x05005713,
|
|
0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38, 0x92d28e9b,
|
|
0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, 0x86d3d2d4, 0xf1d4e242,
|
|
0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1,
|
|
0x18b74777, 0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c,
|
|
0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45, 0xa00ae278,
|
|
0xd70dd2ee, 0x4e048354, 0x3903b3c2, 0xa7672661, 0xd06016f7,
|
|
0x4969474d, 0x3e6e77db, 0xaed16a4a, 0xd9d65adc, 0x40df0b66,
|
|
0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
|
|
0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605,
|
|
0xcdd70693, 0x54de5729, 0x23d967bf, 0xb3667a2e, 0xc4614ab8,
|
|
0x5d681b02, 0x2a6f2b94, 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b,
|
|
0x2d02ef8d
|
|
@};
|
|
unsigned char *end;
|
|
|
|
crc = ~crc & 0xffffffff;
|
|
for (end = buf + len; buf < end; ++buf)
|
|
crc = crc32_table[(crc ^ *buf) & 0xff] ^ (crc >> 8);
|
|
return ~crc & 0xffffffff;
|
|
@}
|
|
@end smallexample
|
|
|
|
@noindent
|
|
This computation does not apply to the ``build ID'' method.
|
|
|
|
|
|
@node Index Files
|
|
@section Index Files Speed Up @value{GDBN}
|
|
@cindex index files
|
|
@cindex @samp{.gdb_index} section
|
|
|
|
When @value{GDBN} finds a symbol file, it scans the symbols in the
|
|
file in order to construct an internal symbol table. This lets most
|
|
@value{GDBN} operations work quickly---at the cost of a delay early
|
|
on. For large programs, this delay can be quite lengthy, so
|
|
@value{GDBN} provides a way to build an index, which speeds up
|
|
startup.
|
|
|
|
The index is stored as a section in the symbol file. @value{GDBN} can
|
|
write the index to a file, then you can put it into the symbol file
|
|
using @command{objcopy}.
|
|
|
|
To create an index file, use the @code{save gdb-index} command:
|
|
|
|
@table @code
|
|
@item save gdb-index @var{directory}
|
|
@kindex save gdb-index
|
|
Create an index file for each symbol file currently known by
|
|
@value{GDBN}. Each file is named after its corresponding symbol file,
|
|
with @samp{.gdb-index} appended, and is written into the given
|
|
@var{directory}.
|
|
@end table
|
|
|
|
Once you have created an index file you can merge it into your symbol
|
|
file, here named @file{symfile}, using @command{objcopy}:
|
|
|
|
@smallexample
|
|
$ objcopy --add-section .gdb_index=symfile.gdb-index \
|
|
--set-section-flags .gdb_index=readonly symfile symfile
|
|
@end smallexample
|
|
|
|
@value{GDBN} will normally ignore older versions of @file{.gdb_index}
|
|
sections that have been deprecated. Usually they are deprecated because
|
|
they are missing a new feature or have performance issues.
|
|
To tell @value{GDBN} to use a deprecated index section anyway
|
|
specify @code{set use-deprecated-index-sections on}.
|
|
The default is @code{off}.
|
|
This can speed up startup, but may result in some functionality being lost.
|
|
@xref{Index Section Format}.
|
|
|
|
@emph{Warning:} Setting @code{use-deprecated-index-sections} to @code{on}
|
|
must be done before gdb reads the file. The following will not work:
|
|
|
|
@smallexample
|
|
$ gdb -ex "set use-deprecated-index-sections on" <program>
|
|
@end smallexample
|
|
|
|
Instead you must do, for example,
|
|
|
|
@smallexample
|
|
$ gdb -iex "set use-deprecated-index-sections on" <program>
|
|
@end smallexample
|
|
|
|
There are currently some limitation on indices. They only work when
|
|
for DWARF debugging information, not stabs. And, they do not
|
|
currently work for programs using Ada.
|
|
|
|
@node Symbol Errors
|
|
@section Errors Reading Symbol Files
|
|
|
|
While reading a symbol file, @value{GDBN} occasionally encounters problems,
|
|
such as symbol types it does not recognize, or known bugs in compiler
|
|
output. By default, @value{GDBN} does not notify you of such problems, since
|
|
they are relatively common and primarily of interest to people
|
|
debugging compilers. If you are interested in seeing information
|
|
about ill-constructed symbol tables, you can either ask @value{GDBN} to print
|
|
only one message about each such type of problem, no matter how many
|
|
times the problem occurs; or you can ask @value{GDBN} to print more messages,
|
|
to see how many times the problems occur, with the @code{set
|
|
complaints} command (@pxref{Messages/Warnings, ,Optional Warnings and
|
|
Messages}).
|
|
|
|
The messages currently printed, and their meanings, include:
|
|
|
|
@table @code
|
|
@item inner block not inside outer block in @var{symbol}
|
|
|
|
The symbol information shows where symbol scopes begin and end
|
|
(such as at the start of a function or a block of statements). This
|
|
error indicates that an inner scope block is not fully contained
|
|
in its outer scope blocks.
|
|
|
|
@value{GDBN} circumvents the problem by treating the inner block as if it had
|
|
the same scope as the outer block. In the error message, @var{symbol}
|
|
may be shown as ``@code{(don't know)}'' if the outer block is not a
|
|
function.
|
|
|
|
@item block at @var{address} out of order
|
|
|
|
The symbol information for symbol scope blocks should occur in
|
|
order of increasing addresses. This error indicates that it does not
|
|
do so.
|
|
|
|
@value{GDBN} does not circumvent this problem, and has trouble
|
|
locating symbols in the source file whose symbols it is reading. (You
|
|
can often determine what source file is affected by specifying
|
|
@code{set verbose on}. @xref{Messages/Warnings, ,Optional Warnings and
|
|
Messages}.)
|
|
|
|
@item bad block start address patched
|
|
|
|
The symbol information for a symbol scope block has a start address
|
|
smaller than the address of the preceding source line. This is known
|
|
to occur in the SunOS 4.1.1 (and earlier) C compiler.
|
|
|
|
@value{GDBN} circumvents the problem by treating the symbol scope block as
|
|
starting on the previous source line.
|
|
|
|
@item bad string table offset in symbol @var{n}
|
|
|
|
@cindex foo
|
|
Symbol number @var{n} contains a pointer into the string table which is
|
|
larger than the size of the string table.
|
|
|
|
@value{GDBN} circumvents the problem by considering the symbol to have the
|
|
name @code{foo}, which may cause other problems if many symbols end up
|
|
with this name.
|
|
|
|
@item unknown symbol type @code{0x@var{nn}}
|
|
|
|
The symbol information contains new data types that @value{GDBN} does
|
|
not yet know how to read. @code{0x@var{nn}} is the symbol type of the
|
|
uncomprehended information, in hexadecimal.
|
|
|
|
@value{GDBN} circumvents the error by ignoring this symbol information.
|
|
This usually allows you to debug your program, though certain symbols
|
|
are not accessible. If you encounter such a problem and feel like
|
|
debugging it, you can debug @code{@value{GDBP}} with itself, breakpoint
|
|
on @code{complain}, then go up to the function @code{read_dbx_symtab}
|
|
and examine @code{*bufp} to see the symbol.
|
|
|
|
@item stub type has NULL name
|
|
|
|
@value{GDBN} could not find the full definition for a struct or class.
|
|
|
|
@item const/volatile indicator missing (ok if using g++ v1.x), got@dots{}
|
|
The symbol information for a C@t{++} member function is missing some
|
|
information that recent versions of the compiler should have output for
|
|
it.
|
|
|
|
@item info mismatch between compiler and debugger
|
|
|
|
@value{GDBN} could not parse a type specification output by the compiler.
|
|
|
|
@end table
|
|
|
|
@node Data Files
|
|
@section GDB Data Files
|
|
|
|
@cindex prefix for data files
|
|
@value{GDBN} will sometimes read an auxiliary data file. These files
|
|
are kept in a directory known as the @dfn{data directory}.
|
|
|
|
You can set the data directory's name, and view the name @value{GDBN}
|
|
is currently using.
|
|
|
|
@table @code
|
|
@kindex set data-directory
|
|
@item set data-directory @var{directory}
|
|
Set the directory which @value{GDBN} searches for auxiliary data files
|
|
to @var{directory}.
|
|
|
|
@kindex show data-directory
|
|
@item show data-directory
|
|
Show the directory @value{GDBN} searches for auxiliary data files.
|
|
@end table
|
|
|
|
@cindex default data directory
|
|
@cindex @samp{--with-gdb-datadir}
|
|
You can set the default data directory by using the configure-time
|
|
@samp{--with-gdb-datadir} option. If the data directory is inside
|
|
@value{GDBN}'s configured binary prefix (set with @samp{--prefix} or
|
|
@samp{--exec-prefix}), then the default data directory will be updated
|
|
automatically if the installed @value{GDBN} is moved to a new
|
|
location.
|
|
|
|
The data directory may also be specified with the
|
|
@code{--data-directory} command line option.
|
|
@xref{Mode Options}.
|
|
|
|
@node Targets
|
|
@chapter Specifying a Debugging Target
|
|
|
|
@cindex debugging target
|
|
A @dfn{target} is the execution environment occupied by your program.
|
|
|
|
Often, @value{GDBN} runs in the same host environment as your program;
|
|
in that case, the debugging target is specified as a side effect when
|
|
you use the @code{file} or @code{core} commands. When you need more
|
|
flexibility---for example, running @value{GDBN} on a physically separate
|
|
host, or controlling a standalone system over a serial port or a
|
|
realtime system over a TCP/IP connection---you can use the @code{target}
|
|
command to specify one of the target types configured for @value{GDBN}
|
|
(@pxref{Target Commands, ,Commands for Managing Targets}).
|
|
|
|
@cindex target architecture
|
|
It is possible to build @value{GDBN} for several different @dfn{target
|
|
architectures}. When @value{GDBN} is built like that, you can choose
|
|
one of the available architectures with the @kbd{set architecture}
|
|
command.
|
|
|
|
@table @code
|
|
@kindex set architecture
|
|
@kindex show architecture
|
|
@item set architecture @var{arch}
|
|
This command sets the current target architecture to @var{arch}. The
|
|
value of @var{arch} can be @code{"auto"}, in addition to one of the
|
|
supported architectures.
|
|
|
|
@item show architecture
|
|
Show the current target architecture.
|
|
|
|
@item set processor
|
|
@itemx processor
|
|
@kindex set processor
|
|
@kindex show processor
|
|
These are alias commands for, respectively, @code{set architecture}
|
|
and @code{show architecture}.
|
|
@end table
|
|
|
|
@menu
|
|
* Active Targets:: Active targets
|
|
* Target Commands:: Commands for managing targets
|
|
* Byte Order:: Choosing target byte order
|
|
@end menu
|
|
|
|
@node Active Targets
|
|
@section Active Targets
|
|
|
|
@cindex stacking targets
|
|
@cindex active targets
|
|
@cindex multiple targets
|
|
|
|
There are multiple classes of targets such as: processes, executable files or
|
|
recording sessions. Core files belong to the process class, making core file
|
|
and process mutually exclusive. Otherwise, @value{GDBN} can work concurrently
|
|
on multiple active targets, one in each class. This allows you to (for
|
|
example) start a process and inspect its activity, while still having access to
|
|
the executable file after the process finishes. Or if you start process
|
|
recording (@pxref{Reverse Execution}) and @code{reverse-step} there, you are
|
|
presented a virtual layer of the recording target, while the process target
|
|
remains stopped at the chronologically last point of the process execution.
|
|
|
|
Use the @code{core-file} and @code{exec-file} commands to select a new core
|
|
file or executable target (@pxref{Files, ,Commands to Specify Files}). To
|
|
specify as a target a process that is already running, use the @code{attach}
|
|
command (@pxref{Attach, ,Debugging an Already-running Process}).
|
|
|
|
@node Target Commands
|
|
@section Commands for Managing Targets
|
|
|
|
@table @code
|
|
@item target @var{type} @var{parameters}
|
|
Connects the @value{GDBN} host environment to a target machine or
|
|
process. A target is typically a protocol for talking to debugging
|
|
facilities. You use the argument @var{type} to specify the type or
|
|
protocol of the target machine.
|
|
|
|
Further @var{parameters} are interpreted by the target protocol, but
|
|
typically include things like device names or host names to connect
|
|
with, process numbers, and baud rates.
|
|
|
|
The @code{target} command does not repeat if you press @key{RET} again
|
|
after executing the command.
|
|
|
|
@kindex help target
|
|
@item help target
|
|
Displays the names of all targets available. To display targets
|
|
currently selected, use either @code{info target} or @code{info files}
|
|
(@pxref{Files, ,Commands to Specify Files}).
|
|
|
|
@item help target @var{name}
|
|
Describe a particular target, including any parameters necessary to
|
|
select it.
|
|
|
|
@kindex set gnutarget
|
|
@item set gnutarget @var{args}
|
|
@value{GDBN} uses its own library BFD to read your files. @value{GDBN}
|
|
knows whether it is reading an @dfn{executable},
|
|
a @dfn{core}, or a @dfn{.o} file; however, you can specify the file format
|
|
with the @code{set gnutarget} command. Unlike most @code{target} commands,
|
|
with @code{gnutarget} the @code{target} refers to a program, not a machine.
|
|
|
|
@quotation
|
|
@emph{Warning:} To specify a file format with @code{set gnutarget},
|
|
you must know the actual BFD name.
|
|
@end quotation
|
|
|
|
@noindent
|
|
@xref{Files, , Commands to Specify Files}.
|
|
|
|
@kindex show gnutarget
|
|
@item show gnutarget
|
|
Use the @code{show gnutarget} command to display what file format
|
|
@code{gnutarget} is set to read. If you have not set @code{gnutarget},
|
|
@value{GDBN} will determine the file format for each file automatically,
|
|
and @code{show gnutarget} displays @samp{The current BDF target is "auto"}.
|
|
@end table
|
|
|
|
@cindex common targets
|
|
Here are some common targets (available, or not, depending on the GDB
|
|
configuration):
|
|
|
|
@table @code
|
|
@kindex target
|
|
@item target exec @var{program}
|
|
@cindex executable file target
|
|
An executable file. @samp{target exec @var{program}} is the same as
|
|
@samp{exec-file @var{program}}.
|
|
|
|
@item target core @var{filename}
|
|
@cindex core dump file target
|
|
A core dump file. @samp{target core @var{filename}} is the same as
|
|
@samp{core-file @var{filename}}.
|
|
|
|
@item target remote @var{medium}
|
|
@cindex remote target
|
|
A remote system connected to @value{GDBN} via a serial line or network
|
|
connection. This command tells @value{GDBN} to use its own remote
|
|
protocol over @var{medium} for debugging. @xref{Remote Debugging}.
|
|
|
|
For example, if you have a board connected to @file{/dev/ttya} on the
|
|
machine running @value{GDBN}, you could say:
|
|
|
|
@smallexample
|
|
target remote /dev/ttya
|
|
@end smallexample
|
|
|
|
@code{target remote} supports the @code{load} command. This is only
|
|
useful if you have some other way of getting the stub to the target
|
|
system, and you can put it somewhere in memory where it won't get
|
|
clobbered by the download.
|
|
|
|
@item target sim @r{[}@var{simargs}@r{]} @dots{}
|
|
@cindex built-in simulator target
|
|
Builtin CPU simulator. @value{GDBN} includes simulators for most architectures.
|
|
In general,
|
|
@smallexample
|
|
target sim
|
|
load
|
|
run
|
|
@end smallexample
|
|
@noindent
|
|
works; however, you cannot assume that a specific memory map, device
|
|
drivers, or even basic I/O is available, although some simulators do
|
|
provide these. For info about any processor-specific simulator details,
|
|
see the appropriate section in @ref{Embedded Processors, ,Embedded
|
|
Processors}.
|
|
|
|
@end table
|
|
|
|
Some configurations may include these targets as well:
|
|
|
|
@table @code
|
|
|
|
@item target nrom @var{dev}
|
|
@cindex NetROM ROM emulator target
|
|
NetROM ROM emulator. This target only supports downloading.
|
|
|
|
@end table
|
|
|
|
Different targets are available on different configurations of @value{GDBN};
|
|
your configuration may have more or fewer targets.
|
|
|
|
Many remote targets require you to download the executable's code once
|
|
you've successfully established a connection. You may wish to control
|
|
various aspects of this process.
|
|
|
|
@table @code
|
|
|
|
@item set hash
|
|
@kindex set hash@r{, for remote monitors}
|
|
@cindex hash mark while downloading
|
|
This command controls whether a hash mark @samp{#} is displayed while
|
|
downloading a file to the remote monitor. If on, a hash mark is
|
|
displayed after each S-record is successfully downloaded to the
|
|
monitor.
|
|
|
|
@item show hash
|
|
@kindex show hash@r{, for remote monitors}
|
|
Show the current status of displaying the hash mark.
|
|
|
|
@item set debug monitor
|
|
@kindex set debug monitor
|
|
@cindex display remote monitor communications
|
|
Enable or disable display of communications messages between
|
|
@value{GDBN} and the remote monitor.
|
|
|
|
@item show debug monitor
|
|
@kindex show debug monitor
|
|
Show the current status of displaying communications between
|
|
@value{GDBN} and the remote monitor.
|
|
@end table
|
|
|
|
@table @code
|
|
|
|
@kindex load @var{filename}
|
|
@item load @var{filename}
|
|
@anchor{load}
|
|
Depending on what remote debugging facilities are configured into
|
|
@value{GDBN}, the @code{load} command may be available. Where it exists, it
|
|
is meant to make @var{filename} (an executable) available for debugging
|
|
on the remote system---by downloading, or dynamic linking, for example.
|
|
@code{load} also records the @var{filename} symbol table in @value{GDBN}, like
|
|
the @code{add-symbol-file} command.
|
|
|
|
If your @value{GDBN} does not have a @code{load} command, attempting to
|
|
execute it gets the error message ``@code{You can't do that when your
|
|
target is @dots{}}''
|
|
|
|
The file is loaded at whatever address is specified in the executable.
|
|
For some object file formats, you can specify the load address when you
|
|
link the program; for other formats, like a.out, the object file format
|
|
specifies a fixed address.
|
|
@c FIXME! This would be a good place for an xref to the GNU linker doc.
|
|
|
|
Depending on the remote side capabilities, @value{GDBN} may be able to
|
|
load programs into flash memory.
|
|
|
|
@code{load} does not repeat if you press @key{RET} again after using it.
|
|
@end table
|
|
|
|
@node Byte Order
|
|
@section Choosing Target Byte Order
|
|
|
|
@cindex choosing target byte order
|
|
@cindex target byte order
|
|
|
|
Some types of processors, such as the @acronym{MIPS}, PowerPC, and Renesas SH,
|
|
offer the ability to run either big-endian or little-endian byte
|
|
orders. Usually the executable or symbol will include a bit to
|
|
designate the endian-ness, and you will not need to worry about
|
|
which to use. However, you may still find it useful to adjust
|
|
@value{GDBN}'s idea of processor endian-ness manually.
|
|
|
|
@table @code
|
|
@kindex set endian
|
|
@item set endian big
|
|
Instruct @value{GDBN} to assume the target is big-endian.
|
|
|
|
@item set endian little
|
|
Instruct @value{GDBN} to assume the target is little-endian.
|
|
|
|
@item set endian auto
|
|
Instruct @value{GDBN} to use the byte order associated with the
|
|
executable.
|
|
|
|
@item show endian
|
|
Display @value{GDBN}'s current idea of the target byte order.
|
|
|
|
@end table
|
|
|
|
Note that these commands merely adjust interpretation of symbolic
|
|
data on the host, and that they have absolutely no effect on the
|
|
target system.
|
|
|
|
|
|
@node Remote Debugging
|
|
@chapter Debugging Remote Programs
|
|
@cindex remote debugging
|
|
|
|
If you are trying to debug a program running on a machine that cannot run
|
|
@value{GDBN} in the usual way, it is often useful to use remote debugging.
|
|
For example, you might use remote debugging on an operating system kernel,
|
|
or on a small system which does not have a general purpose operating system
|
|
powerful enough to run a full-featured debugger.
|
|
|
|
Some configurations of @value{GDBN} have special serial or TCP/IP interfaces
|
|
to make this work with particular debugging targets. In addition,
|
|
@value{GDBN} comes with a generic serial protocol (specific to @value{GDBN},
|
|
but not specific to any particular target system) which you can use if you
|
|
write the remote stubs---the code that runs on the remote system to
|
|
communicate with @value{GDBN}.
|
|
|
|
Other remote targets may be available in your
|
|
configuration of @value{GDBN}; use @code{help target} to list them.
|
|
|
|
@menu
|
|
* Connecting:: Connecting to a remote target
|
|
* File Transfer:: Sending files to a remote system
|
|
* Server:: Using the gdbserver program
|
|
* Remote Configuration:: Remote configuration
|
|
* Remote Stub:: Implementing a remote stub
|
|
@end menu
|
|
|
|
@node Connecting
|
|
@section Connecting to a Remote Target
|
|
|
|
On the @value{GDBN} host machine, you will need an unstripped copy of
|
|
your program, since @value{GDBN} needs symbol and debugging information.
|
|
Start up @value{GDBN} as usual, using the name of the local copy of your
|
|
program as the first argument.
|
|
|
|
@cindex @code{target remote}
|
|
@value{GDBN} can communicate with the target over a serial line, or
|
|
over an @acronym{IP} network using @acronym{TCP} or @acronym{UDP}. In
|
|
each case, @value{GDBN} uses the same protocol for debugging your
|
|
program; only the medium carrying the debugging packets varies. The
|
|
@code{target remote} command establishes a connection to the target.
|
|
Its arguments indicate which medium to use:
|
|
|
|
@table @code
|
|
|
|
@item target remote @var{serial-device}
|
|
@cindex serial line, @code{target remote}
|
|
Use @var{serial-device} to communicate with the target. For example,
|
|
to use a serial line connected to the device named @file{/dev/ttyb}:
|
|
|
|
@smallexample
|
|
target remote /dev/ttyb
|
|
@end smallexample
|
|
|
|
If you're using a serial line, you may want to give @value{GDBN} the
|
|
@w{@samp{--baud}} option, or use the @code{set remotebaud} command
|
|
(@pxref{Remote Configuration, set remotebaud}) before the
|
|
@code{target} command.
|
|
|
|
@item target remote @code{@var{host}:@var{port}}
|
|
@itemx target remote @code{tcp:@var{host}:@var{port}}
|
|
@cindex @acronym{TCP} port, @code{target remote}
|
|
Debug using a @acronym{TCP} connection to @var{port} on @var{host}.
|
|
The @var{host} may be either a host name or a numeric @acronym{IP}
|
|
address; @var{port} must be a decimal number. The @var{host} could be
|
|
the target machine itself, if it is directly connected to the net, or
|
|
it might be a terminal server which in turn has a serial line to the
|
|
target.
|
|
|
|
For example, to connect to port 2828 on a terminal server named
|
|
@code{manyfarms}:
|
|
|
|
@smallexample
|
|
target remote manyfarms:2828
|
|
@end smallexample
|
|
|
|
If your remote target is actually running on the same machine as your
|
|
debugger session (e.g.@: a simulator for your target running on the
|
|
same host), you can omit the hostname. For example, to connect to
|
|
port 1234 on your local machine:
|
|
|
|
@smallexample
|
|
target remote :1234
|
|
@end smallexample
|
|
@noindent
|
|
|
|
Note that the colon is still required here.
|
|
|
|
@item target remote @code{udp:@var{host}:@var{port}}
|
|
@cindex @acronym{UDP} port, @code{target remote}
|
|
Debug using @acronym{UDP} packets to @var{port} on @var{host}. For example, to
|
|
connect to @acronym{UDP} port 2828 on a terminal server named @code{manyfarms}:
|
|
|
|
@smallexample
|
|
target remote udp:manyfarms:2828
|
|
@end smallexample
|
|
|
|
When using a @acronym{UDP} connection for remote debugging, you should
|
|
keep in mind that the `U' stands for ``Unreliable''. @acronym{UDP}
|
|
can silently drop packets on busy or unreliable networks, which will
|
|
cause havoc with your debugging session.
|
|
|
|
@item target remote | @var{command}
|
|
@cindex pipe, @code{target remote} to
|
|
Run @var{command} in the background and communicate with it using a
|
|
pipe. The @var{command} is a shell command, to be parsed and expanded
|
|
by the system's command shell, @code{/bin/sh}; it should expect remote
|
|
protocol packets on its standard input, and send replies on its
|
|
standard output. You could use this to run a stand-alone simulator
|
|
that speaks the remote debugging protocol, to make net connections
|
|
using programs like @code{ssh}, or for other similar tricks.
|
|
|
|
If @var{command} closes its standard output (perhaps by exiting),
|
|
@value{GDBN} will try to send it a @code{SIGTERM} signal. (If the
|
|
program has already exited, this will have no effect.)
|
|
|
|
@end table
|
|
|
|
Once the connection has been established, you can use all the usual
|
|
commands to examine and change data. The remote program is already
|
|
running; you can use @kbd{step} and @kbd{continue}, and you do not
|
|
need to use @kbd{run}.
|
|
|
|
@cindex interrupting remote programs
|
|
@cindex remote programs, interrupting
|
|
Whenever @value{GDBN} is waiting for the remote program, if you type the
|
|
interrupt character (often @kbd{Ctrl-c}), @value{GDBN} attempts to stop the
|
|
program. This may or may not succeed, depending in part on the hardware
|
|
and the serial drivers the remote system uses. If you type the
|
|
interrupt character once again, @value{GDBN} displays this prompt:
|
|
|
|
@smallexample
|
|
Interrupted while waiting for the program.
|
|
Give up (and stop debugging it)? (y or n)
|
|
@end smallexample
|
|
|
|
If you type @kbd{y}, @value{GDBN} abandons the remote debugging session.
|
|
(If you decide you want to try again later, you can use @samp{target
|
|
remote} again to connect once more.) If you type @kbd{n}, @value{GDBN}
|
|
goes back to waiting.
|
|
|
|
@table @code
|
|
@kindex detach (remote)
|
|
@item detach
|
|
When you have finished debugging the remote program, you can use the
|
|
@code{detach} command to release it from @value{GDBN} control.
|
|
Detaching from the target normally resumes its execution, but the results
|
|
will depend on your particular remote stub. After the @code{detach}
|
|
command, @value{GDBN} is free to connect to another target.
|
|
|
|
@kindex disconnect
|
|
@item disconnect
|
|
The @code{disconnect} command behaves like @code{detach}, except that
|
|
the target is generally not resumed. It will wait for @value{GDBN}
|
|
(this instance or another one) to connect and continue debugging. After
|
|
the @code{disconnect} command, @value{GDBN} is again free to connect to
|
|
another target.
|
|
|
|
@cindex send command to remote monitor
|
|
@cindex extend @value{GDBN} for remote targets
|
|
@cindex add new commands for external monitor
|
|
@kindex monitor
|
|
@item monitor @var{cmd}
|
|
This command allows you to send arbitrary commands directly to the
|
|
remote monitor. Since @value{GDBN} doesn't care about the commands it
|
|
sends like this, this command is the way to extend @value{GDBN}---you
|
|
can add new commands that only the external monitor will understand
|
|
and implement.
|
|
@end table
|
|
|
|
@node File Transfer
|
|
@section Sending files to a remote system
|
|
@cindex remote target, file transfer
|
|
@cindex file transfer
|
|
@cindex sending files to remote systems
|
|
|
|
Some remote targets offer the ability to transfer files over the same
|
|
connection used to communicate with @value{GDBN}. This is convenient
|
|
for targets accessible through other means, e.g.@: @sc{gnu}/Linux systems
|
|
running @code{gdbserver} over a network interface. For other targets,
|
|
e.g.@: embedded devices with only a single serial port, this may be
|
|
the only way to upload or download files.
|
|
|
|
Not all remote targets support these commands.
|
|
|
|
@table @code
|
|
@kindex remote put
|
|
@item remote put @var{hostfile} @var{targetfile}
|
|
Copy file @var{hostfile} from the host system (the machine running
|
|
@value{GDBN}) to @var{targetfile} on the target system.
|
|
|
|
@kindex remote get
|
|
@item remote get @var{targetfile} @var{hostfile}
|
|
Copy file @var{targetfile} from the target system to @var{hostfile}
|
|
on the host system.
|
|
|
|
@kindex remote delete
|
|
@item remote delete @var{targetfile}
|
|
Delete @var{targetfile} from the target system.
|
|
|
|
@end table
|
|
|
|
@node Server
|
|
@section Using the @code{gdbserver} Program
|
|
|
|
@kindex gdbserver
|
|
@cindex remote connection without stubs
|
|
@code{gdbserver} is a control program for Unix-like systems, which
|
|
allows you to connect your program with a remote @value{GDBN} via
|
|
@code{target remote}---but without linking in the usual debugging stub.
|
|
|
|
@code{gdbserver} is not a complete replacement for the debugging stubs,
|
|
because it requires essentially the same operating-system facilities
|
|
that @value{GDBN} itself does. In fact, a system that can run
|
|
@code{gdbserver} to connect to a remote @value{GDBN} could also run
|
|
@value{GDBN} locally! @code{gdbserver} is sometimes useful nevertheless,
|
|
because it is a much smaller program than @value{GDBN} itself. It is
|
|
also easier to port than all of @value{GDBN}, so you may be able to get
|
|
started more quickly on a new system by using @code{gdbserver}.
|
|
Finally, if you develop code for real-time systems, you may find that
|
|
the tradeoffs involved in real-time operation make it more convenient to
|
|
do as much development work as possible on another system, for example
|
|
by cross-compiling. You can use @code{gdbserver} to make a similar
|
|
choice for debugging.
|
|
|
|
@value{GDBN} and @code{gdbserver} communicate via either a serial line
|
|
or a TCP connection, using the standard @value{GDBN} remote serial
|
|
protocol.
|
|
|
|
@quotation
|
|
@emph{Warning:} @code{gdbserver} does not have any built-in security.
|
|
Do not run @code{gdbserver} connected to any public network; a
|
|
@value{GDBN} connection to @code{gdbserver} provides access to the
|
|
target system with the same privileges as the user running
|
|
@code{gdbserver}.
|
|
@end quotation
|
|
|
|
@subsection Running @code{gdbserver}
|
|
@cindex arguments, to @code{gdbserver}
|
|
@cindex @code{gdbserver}, command-line arguments
|
|
|
|
Run @code{gdbserver} on the target system. You need a copy of the
|
|
program you want to debug, including any libraries it requires.
|
|
@code{gdbserver} does not need your program's symbol table, so you can
|
|
strip the program if necessary to save space. @value{GDBN} on the host
|
|
system does all the symbol handling.
|
|
|
|
To use the server, you must tell it how to communicate with @value{GDBN};
|
|
the name of your program; and the arguments for your program. The usual
|
|
syntax is:
|
|
|
|
@smallexample
|
|
target> gdbserver @var{comm} @var{program} [ @var{args} @dots{} ]
|
|
@end smallexample
|
|
|
|
@var{comm} is either a device name (to use a serial line), or a TCP
|
|
hostname and portnumber, or @code{-} or @code{stdio} to use
|
|
stdin/stdout of @code{gdbserver}.
|
|
For example, to debug Emacs with the argument
|
|
@samp{foo.txt} and communicate with @value{GDBN} over the serial port
|
|
@file{/dev/com1}:
|
|
|
|
@smallexample
|
|
target> gdbserver /dev/com1 emacs foo.txt
|
|
@end smallexample
|
|
|
|
@code{gdbserver} waits passively for the host @value{GDBN} to communicate
|
|
with it.
|
|
|
|
To use a TCP connection instead of a serial line:
|
|
|
|
@smallexample
|
|
target> gdbserver host:2345 emacs foo.txt
|
|
@end smallexample
|
|
|
|
The only difference from the previous example is the first argument,
|
|
specifying that you are communicating with the host @value{GDBN} via
|
|
TCP. The @samp{host:2345} argument means that @code{gdbserver} is to
|
|
expect a TCP connection from machine @samp{host} to local TCP port 2345.
|
|
(Currently, the @samp{host} part is ignored.) You can choose any number
|
|
you want for the port number as long as it does not conflict with any
|
|
TCP ports already in use on the target system (for example, @code{23} is
|
|
reserved for @code{telnet}).@footnote{If you choose a port number that
|
|
conflicts with another service, @code{gdbserver} prints an error message
|
|
and exits.} You must use the same port number with the host @value{GDBN}
|
|
@code{target remote} command.
|
|
|
|
The @code{stdio} connection is useful when starting @code{gdbserver}
|
|
with ssh:
|
|
|
|
@smallexample
|
|
(gdb) target remote | ssh -T hostname gdbserver - hello
|
|
@end smallexample
|
|
|
|
The @samp{-T} option to ssh is provided because we don't need a remote pty,
|
|
and we don't want escape-character handling. Ssh does this by default when
|
|
a command is provided, the flag is provided to make it explicit.
|
|
You could elide it if you want to.
|
|
|
|
Programs started with stdio-connected gdbserver have @file{/dev/null} for
|
|
@code{stdin}, and @code{stdout},@code{stderr} are sent back to gdb for
|
|
display through a pipe connected to gdbserver.
|
|
Both @code{stdout} and @code{stderr} use the same pipe.
|
|
|
|
@subsubsection Attaching to a Running Program
|
|
@cindex attach to a program, @code{gdbserver}
|
|
@cindex @option{--attach}, @code{gdbserver} option
|
|
|
|
On some targets, @code{gdbserver} can also attach to running programs.
|
|
This is accomplished via the @code{--attach} argument. The syntax is:
|
|
|
|
@smallexample
|
|
target> gdbserver --attach @var{comm} @var{pid}
|
|
@end smallexample
|
|
|
|
@var{pid} is the process ID of a currently running process. It isn't necessary
|
|
to point @code{gdbserver} at a binary for the running process.
|
|
|
|
@pindex pidof
|
|
You can debug processes by name instead of process ID if your target has the
|
|
@code{pidof} utility:
|
|
|
|
@smallexample
|
|
target> gdbserver --attach @var{comm} `pidof @var{program}`
|
|
@end smallexample
|
|
|
|
In case more than one copy of @var{program} is running, or @var{program}
|
|
has multiple threads, most versions of @code{pidof} support the
|
|
@code{-s} option to only return the first process ID.
|
|
|
|
@subsubsection Multi-Process Mode for @code{gdbserver}
|
|
@cindex @code{gdbserver}, multiple processes
|
|
@cindex multiple processes with @code{gdbserver}
|
|
|
|
When you connect to @code{gdbserver} using @code{target remote},
|
|
@code{gdbserver} debugs the specified program only once. When the
|
|
program exits, or you detach from it, @value{GDBN} closes the connection
|
|
and @code{gdbserver} exits.
|
|
|
|
If you connect using @kbd{target extended-remote}, @code{gdbserver}
|
|
enters multi-process mode. When the debugged program exits, or you
|
|
detach from it, @value{GDBN} stays connected to @code{gdbserver} even
|
|
though no program is running. The @code{run} and @code{attach}
|
|
commands instruct @code{gdbserver} to run or attach to a new program.
|
|
The @code{run} command uses @code{set remote exec-file} (@pxref{set
|
|
remote exec-file}) to select the program to run. Command line
|
|
arguments are supported, except for wildcard expansion and I/O
|
|
redirection (@pxref{Arguments}).
|
|
|
|
@cindex @option{--multi}, @code{gdbserver} option
|
|
To start @code{gdbserver} without supplying an initial command to run
|
|
or process ID to attach, use the @option{--multi} command line option.
|
|
Then you can connect using @kbd{target extended-remote} and start
|
|
the program you want to debug.
|
|
|
|
In multi-process mode @code{gdbserver} does not automatically exit unless you
|
|
use the option @option{--once}. You can terminate it by using
|
|
@code{monitor exit} (@pxref{Monitor Commands for gdbserver}). Note that the
|
|
conditions under which @code{gdbserver} terminates depend on how @value{GDBN}
|
|
connects to it (@kbd{target remote} or @kbd{target extended-remote}). The
|
|
@option{--multi} option to @code{gdbserver} has no influence on that.
|
|
|
|
@subsubsection TCP port allocation lifecycle of @code{gdbserver}
|
|
|
|
This section applies only when @code{gdbserver} is run to listen on a TCP port.
|
|
|
|
@code{gdbserver} normally terminates after all of its debugged processes have
|
|
terminated in @kbd{target remote} mode. On the other hand, for @kbd{target
|
|
extended-remote}, @code{gdbserver} stays running even with no processes left.
|
|
@value{GDBN} normally terminates the spawned debugged process on its exit,
|
|
which normally also terminates @code{gdbserver} in the @kbd{target remote}
|
|
mode. Therefore, when the connection drops unexpectedly, and @value{GDBN}
|
|
cannot ask @code{gdbserver} to kill its debugged processes, @code{gdbserver}
|
|
stays running even in the @kbd{target remote} mode.
|
|
|
|
When @code{gdbserver} stays running, @value{GDBN} can connect to it again later.
|
|
Such reconnecting is useful for features like @ref{disconnected tracing}. For
|
|
completeness, at most one @value{GDBN} can be connected at a time.
|
|
|
|
@cindex @option{--once}, @code{gdbserver} option
|
|
By default, @code{gdbserver} keeps the listening TCP port open, so that
|
|
additional connections are possible. However, if you start @code{gdbserver}
|
|
with the @option{--once} option, it will stop listening for any further
|
|
connection attempts after connecting to the first @value{GDBN} session. This
|
|
means no further connections to @code{gdbserver} will be possible after the
|
|
first one. It also means @code{gdbserver} will terminate after the first
|
|
connection with remote @value{GDBN} has closed, even for unexpectedly closed
|
|
connections and even in the @kbd{target extended-remote} mode. The
|
|
@option{--once} option allows reusing the same port number for connecting to
|
|
multiple instances of @code{gdbserver} running on the same host, since each
|
|
instance closes its port after the first connection.
|
|
|
|
@subsubsection Other Command-Line Arguments for @code{gdbserver}
|
|
|
|
@cindex @option{--debug}, @code{gdbserver} option
|
|
The @option{--debug} option tells @code{gdbserver} to display extra
|
|
status information about the debugging process.
|
|
@cindex @option{--remote-debug}, @code{gdbserver} option
|
|
The @option{--remote-debug} option tells @code{gdbserver} to display
|
|
remote protocol debug output. These options are intended for
|
|
@code{gdbserver} development and for bug reports to the developers.
|
|
|
|
@cindex @option{--wrapper}, @code{gdbserver} option
|
|
The @option{--wrapper} option specifies a wrapper to launch programs
|
|
for debugging. The option should be followed by the name of the
|
|
wrapper, then any command-line arguments to pass to the wrapper, then
|
|
@kbd{--} indicating the end of the wrapper arguments.
|
|
|
|
@code{gdbserver} runs the specified wrapper program with a combined
|
|
command line including the wrapper arguments, then the name of the
|
|
program to debug, then any arguments to the program. The wrapper
|
|
runs until it executes your program, and then @value{GDBN} gains control.
|
|
|
|
You can use any program that eventually calls @code{execve} with
|
|
its arguments as a wrapper. Several standard Unix utilities do
|
|
this, e.g.@: @code{env} and @code{nohup}. Any Unix shell script ending
|
|
with @code{exec "$@@"} will also work.
|
|
|
|
For example, you can use @code{env} to pass an environment variable to
|
|
the debugged program, without setting the variable in @code{gdbserver}'s
|
|
environment:
|
|
|
|
@smallexample
|
|
$ gdbserver --wrapper env LD_PRELOAD=libtest.so -- :2222 ./testprog
|
|
@end smallexample
|
|
|
|
@subsection Connecting to @code{gdbserver}
|
|
|
|
Run @value{GDBN} on the host system.
|
|
|
|
First make sure you have the necessary symbol files. Load symbols for
|
|
your application using the @code{file} command before you connect. Use
|
|
@code{set sysroot} to locate target libraries (unless your @value{GDBN}
|
|
was compiled with the correct sysroot using @code{--with-sysroot}).
|
|
|
|
The symbol file and target libraries must exactly match the executable
|
|
and libraries on the target, with one exception: the files on the host
|
|
system should not be stripped, even if the files on the target system
|
|
are. Mismatched or missing files will lead to confusing results
|
|
during debugging. On @sc{gnu}/Linux targets, mismatched or missing
|
|
files may also prevent @code{gdbserver} from debugging multi-threaded
|
|
programs.
|
|
|
|
Connect to your target (@pxref{Connecting,,Connecting to a Remote Target}).
|
|
For TCP connections, you must start up @code{gdbserver} prior to using
|
|
the @code{target remote} command. Otherwise you may get an error whose
|
|
text depends on the host system, but which usually looks something like
|
|
@samp{Connection refused}. Don't use the @code{load}
|
|
command in @value{GDBN} when using @code{gdbserver}, since the program is
|
|
already on the target.
|
|
|
|
@subsection Monitor Commands for @code{gdbserver}
|
|
@cindex monitor commands, for @code{gdbserver}
|
|
@anchor{Monitor Commands for gdbserver}
|
|
|
|
During a @value{GDBN} session using @code{gdbserver}, you can use the
|
|
@code{monitor} command to send special requests to @code{gdbserver}.
|
|
Here are the available commands.
|
|
|
|
@table @code
|
|
@item monitor help
|
|
List the available monitor commands.
|
|
|
|
@item monitor set debug 0
|
|
@itemx monitor set debug 1
|
|
Disable or enable general debugging messages.
|
|
|
|
@item monitor set remote-debug 0
|
|
@itemx monitor set remote-debug 1
|
|
Disable or enable specific debugging messages associated with the remote
|
|
protocol (@pxref{Remote Protocol}).
|
|
|
|
@item monitor set libthread-db-search-path [PATH]
|
|
@cindex gdbserver, search path for @code{libthread_db}
|
|
When this command is issued, @var{path} is a colon-separated list of
|
|
directories to search for @code{libthread_db} (@pxref{Threads,,set
|
|
libthread-db-search-path}). If you omit @var{path},
|
|
@samp{libthread-db-search-path} will be reset to its default value.
|
|
|
|
The special entry @samp{$pdir} for @samp{libthread-db-search-path} is
|
|
not supported in @code{gdbserver}.
|
|
|
|
@item monitor exit
|
|
Tell gdbserver to exit immediately. This command should be followed by
|
|
@code{disconnect} to close the debugging session. @code{gdbserver} will
|
|
detach from any attached processes and kill any processes it created.
|
|
Use @code{monitor exit} to terminate @code{gdbserver} at the end
|
|
of a multi-process mode debug session.
|
|
|
|
@end table
|
|
|
|
@subsection Tracepoints support in @code{gdbserver}
|
|
@cindex tracepoints support in @code{gdbserver}
|
|
|
|
On some targets, @code{gdbserver} supports tracepoints, fast
|
|
tracepoints and static tracepoints.
|
|
|
|
For fast or static tracepoints to work, a special library called the
|
|
@dfn{in-process agent} (IPA), must be loaded in the inferior process.
|
|
This library is built and distributed as an integral part of
|
|
@code{gdbserver}. In addition, support for static tracepoints
|
|
requires building the in-process agent library with static tracepoints
|
|
support. At present, the UST (LTTng Userspace Tracer,
|
|
@url{http://lttng.org/ust}) tracing engine is supported. This support
|
|
is automatically available if UST development headers are found in the
|
|
standard include path when @code{gdbserver} is built, or if
|
|
@code{gdbserver} was explicitly configured using @option{--with-ust}
|
|
to point at such headers. You can explicitly disable the support
|
|
using @option{--with-ust=no}.
|
|
|
|
There are several ways to load the in-process agent in your program:
|
|
|
|
@table @code
|
|
@item Specifying it as dependency at link time
|
|
|
|
You can link your program dynamically with the in-process agent
|
|
library. On most systems, this is accomplished by adding
|
|
@code{-linproctrace} to the link command.
|
|
|
|
@item Using the system's preloading mechanisms
|
|
|
|
You can force loading the in-process agent at startup time by using
|
|
your system's support for preloading shared libraries. Many Unixes
|
|
support the concept of preloading user defined libraries. In most
|
|
cases, you do that by specifying @code{LD_PRELOAD=libinproctrace.so}
|
|
in the environment. See also the description of @code{gdbserver}'s
|
|
@option{--wrapper} command line option.
|
|
|
|
@item Using @value{GDBN} to force loading the agent at run time
|
|
|
|
On some systems, you can force the inferior to load a shared library,
|
|
by calling a dynamic loader function in the inferior that takes care
|
|
of dynamically looking up and loading a shared library. On most Unix
|
|
systems, the function is @code{dlopen}. You'll use the @code{call}
|
|
command for that. For example:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) call dlopen ("libinproctrace.so", ...)
|
|
@end smallexample
|
|
|
|
Note that on most Unix systems, for the @code{dlopen} function to be
|
|
available, the program needs to be linked with @code{-ldl}.
|
|
@end table
|
|
|
|
On systems that have a userspace dynamic loader, like most Unix
|
|
systems, when you connect to @code{gdbserver} using @code{target
|
|
remote}, you'll find that the program is stopped at the dynamic
|
|
loader's entry point, and no shared library has been loaded in the
|
|
program's address space yet, including the in-process agent. In that
|
|
case, before being able to use any of the fast or static tracepoints
|
|
features, you need to let the loader run and load the shared
|
|
libraries. The simplest way to do that is to run the program to the
|
|
main procedure. E.g., if debugging a C or C@t{++} program, start
|
|
@code{gdbserver} like so:
|
|
|
|
@smallexample
|
|
$ gdbserver :9999 myprogram
|
|
@end smallexample
|
|
|
|
Start GDB and connect to @code{gdbserver} like so, and run to main:
|
|
|
|
@smallexample
|
|
$ gdb myprogram
|
|
(@value{GDBP}) target remote myhost:9999
|
|
0x00007f215893ba60 in ?? () from /lib64/ld-linux-x86-64.so.2
|
|
(@value{GDBP}) b main
|
|
(@value{GDBP}) continue
|
|
@end smallexample
|
|
|
|
The in-process tracing agent library should now be loaded into the
|
|
process; you can confirm it with the @code{info sharedlibrary}
|
|
command, which will list @file{libinproctrace.so} as loaded in the
|
|
process. You are now ready to install fast tracepoints, list static
|
|
tracepoint markers, probe static tracepoints markers, and start
|
|
tracing.
|
|
|
|
@node Remote Configuration
|
|
@section Remote Configuration
|
|
|
|
@kindex set remote
|
|
@kindex show remote
|
|
This section documents the configuration options available when
|
|
debugging remote programs. For the options related to the File I/O
|
|
extensions of the remote protocol, see @ref{system,
|
|
system-call-allowed}.
|
|
|
|
@table @code
|
|
@item set remoteaddresssize @var{bits}
|
|
@cindex address size for remote targets
|
|
@cindex bits in remote address
|
|
Set the maximum size of address in a memory packet to the specified
|
|
number of bits. @value{GDBN} will mask off the address bits above
|
|
that number, when it passes addresses to the remote target. The
|
|
default value is the number of bits in the target's address.
|
|
|
|
@item show remoteaddresssize
|
|
Show the current value of remote address size in bits.
|
|
|
|
@item set remotebaud @var{n}
|
|
@cindex baud rate for remote targets
|
|
Set the baud rate for the remote serial I/O to @var{n} baud. The
|
|
value is used to set the speed of the serial port used for debugging
|
|
remote targets.
|
|
|
|
@item show remotebaud
|
|
Show the current speed of the remote connection.
|
|
|
|
@item set remotebreak
|
|
@cindex interrupt remote programs
|
|
@cindex BREAK signal instead of Ctrl-C
|
|
@anchor{set remotebreak}
|
|
If set to on, @value{GDBN} sends a @code{BREAK} signal to the remote
|
|
when you type @kbd{Ctrl-c} to interrupt the program running
|
|
on the remote. If set to off, @value{GDBN} sends the @samp{Ctrl-C}
|
|
character instead. The default is off, since most remote systems
|
|
expect to see @samp{Ctrl-C} as the interrupt signal.
|
|
|
|
@item show remotebreak
|
|
Show whether @value{GDBN} sends @code{BREAK} or @samp{Ctrl-C} to
|
|
interrupt the remote program.
|
|
|
|
@item set remoteflow on
|
|
@itemx set remoteflow off
|
|
@kindex set remoteflow
|
|
Enable or disable hardware flow control (@code{RTS}/@code{CTS})
|
|
on the serial port used to communicate to the remote target.
|
|
|
|
@item show remoteflow
|
|
@kindex show remoteflow
|
|
Show the current setting of hardware flow control.
|
|
|
|
@item set remotelogbase @var{base}
|
|
Set the base (a.k.a.@: radix) of logging serial protocol
|
|
communications to @var{base}. Supported values of @var{base} are:
|
|
@code{ascii}, @code{octal}, and @code{hex}. The default is
|
|
@code{ascii}.
|
|
|
|
@item show remotelogbase
|
|
Show the current setting of the radix for logging remote serial
|
|
protocol.
|
|
|
|
@item set remotelogfile @var{file}
|
|
@cindex record serial communications on file
|
|
Record remote serial communications on the named @var{file}. The
|
|
default is not to record at all.
|
|
|
|
@item show remotelogfile.
|
|
Show the current setting of the file name on which to record the
|
|
serial communications.
|
|
|
|
@item set remotetimeout @var{num}
|
|
@cindex timeout for serial communications
|
|
@cindex remote timeout
|
|
Set the timeout limit to wait for the remote target to respond to
|
|
@var{num} seconds. The default is 2 seconds.
|
|
|
|
@item show remotetimeout
|
|
Show the current number of seconds to wait for the remote target
|
|
responses.
|
|
|
|
@cindex limit hardware breakpoints and watchpoints
|
|
@cindex remote target, limit break- and watchpoints
|
|
@anchor{set remote hardware-watchpoint-limit}
|
|
@anchor{set remote hardware-breakpoint-limit}
|
|
@item set remote hardware-watchpoint-limit @var{limit}
|
|
@itemx set remote hardware-breakpoint-limit @var{limit}
|
|
Restrict @value{GDBN} to using @var{limit} remote hardware breakpoint or
|
|
watchpoints. A limit of -1, the default, is treated as unlimited.
|
|
|
|
@cindex limit hardware watchpoints length
|
|
@cindex remote target, limit watchpoints length
|
|
@anchor{set remote hardware-watchpoint-length-limit}
|
|
@item set remote hardware-watchpoint-length-limit @var{limit}
|
|
Restrict @value{GDBN} to using @var{limit} bytes for the maximum length of
|
|
a remote hardware watchpoint. A limit of -1, the default, is treated
|
|
as unlimited.
|
|
|
|
@item show remote hardware-watchpoint-length-limit
|
|
Show the current limit (in bytes) of the maximum length of
|
|
a remote hardware watchpoint.
|
|
|
|
@item set remote exec-file @var{filename}
|
|
@itemx show remote exec-file
|
|
@anchor{set remote exec-file}
|
|
@cindex executable file, for remote target
|
|
Select the file used for @code{run} with @code{target
|
|
extended-remote}. This should be set to a filename valid on the
|
|
target system. If it is not set, the target will use a default
|
|
filename (e.g.@: the last program run).
|
|
|
|
@item set remote interrupt-sequence
|
|
@cindex interrupt remote programs
|
|
@cindex select Ctrl-C, BREAK or BREAK-g
|
|
Allow the user to select one of @samp{Ctrl-C}, a @code{BREAK} or
|
|
@samp{BREAK-g} as the
|
|
sequence to the remote target in order to interrupt the execution.
|
|
@samp{Ctrl-C} is a default. Some system prefers @code{BREAK} which
|
|
is high level of serial line for some certain time.
|
|
Linux kernel prefers @samp{BREAK-g}, a.k.a Magic SysRq g.
|
|
It is @code{BREAK} signal followed by character @code{g}.
|
|
|
|
@item show interrupt-sequence
|
|
Show which of @samp{Ctrl-C}, @code{BREAK} or @code{BREAK-g}
|
|
is sent by @value{GDBN} to interrupt the remote program.
|
|
@code{BREAK-g} is BREAK signal followed by @code{g} and
|
|
also known as Magic SysRq g.
|
|
|
|
@item set remote interrupt-on-connect
|
|
@cindex send interrupt-sequence on start
|
|
Specify whether interrupt-sequence is sent to remote target when
|
|
@value{GDBN} connects to it. This is mostly needed when you debug
|
|
Linux kernel. Linux kernel expects @code{BREAK} followed by @code{g}
|
|
which is known as Magic SysRq g in order to connect @value{GDBN}.
|
|
|
|
@item show interrupt-on-connect
|
|
Show whether interrupt-sequence is sent
|
|
to remote target when @value{GDBN} connects to it.
|
|
|
|
@kindex set tcp
|
|
@kindex show tcp
|
|
@item set tcp auto-retry on
|
|
@cindex auto-retry, for remote TCP target
|
|
Enable auto-retry for remote TCP connections. This is useful if the remote
|
|
debugging agent is launched in parallel with @value{GDBN}; there is a race
|
|
condition because the agent may not become ready to accept the connection
|
|
before @value{GDBN} attempts to connect. When auto-retry is
|
|
enabled, if the initial attempt to connect fails, @value{GDBN} reattempts
|
|
to establish the connection using the timeout specified by
|
|
@code{set tcp connect-timeout}.
|
|
|
|
@item set tcp auto-retry off
|
|
Do not auto-retry failed TCP connections.
|
|
|
|
@item show tcp auto-retry
|
|
Show the current auto-retry setting.
|
|
|
|
@item set tcp connect-timeout @var{seconds}
|
|
@cindex connection timeout, for remote TCP target
|
|
@cindex timeout, for remote target connection
|
|
Set the timeout for establishing a TCP connection to the remote target to
|
|
@var{seconds}. The timeout affects both polling to retry failed connections
|
|
(enabled by @code{set tcp auto-retry on}) and waiting for connections
|
|
that are merely slow to complete, and represents an approximate cumulative
|
|
value.
|
|
|
|
@item show tcp connect-timeout
|
|
Show the current connection timeout setting.
|
|
@end table
|
|
|
|
@cindex remote packets, enabling and disabling
|
|
The @value{GDBN} remote protocol autodetects the packets supported by
|
|
your debugging stub. If you need to override the autodetection, you
|
|
can use these commands to enable or disable individual packets. Each
|
|
packet can be set to @samp{on} (the remote target supports this
|
|
packet), @samp{off} (the remote target does not support this packet),
|
|
or @samp{auto} (detect remote target support for this packet). They
|
|
all default to @samp{auto}. For more information about each packet,
|
|
see @ref{Remote Protocol}.
|
|
|
|
During normal use, you should not have to use any of these commands.
|
|
If you do, that may be a bug in your remote debugging stub, or a bug
|
|
in @value{GDBN}. You may want to report the problem to the
|
|
@value{GDBN} developers.
|
|
|
|
For each packet @var{name}, the command to enable or disable the
|
|
packet is @code{set remote @var{name}-packet}. The available settings
|
|
are:
|
|
|
|
@multitable @columnfractions 0.28 0.32 0.25
|
|
@item Command Name
|
|
@tab Remote Packet
|
|
@tab Related Features
|
|
|
|
@item @code{fetch-register}
|
|
@tab @code{p}
|
|
@tab @code{info registers}
|
|
|
|
@item @code{set-register}
|
|
@tab @code{P}
|
|
@tab @code{set}
|
|
|
|
@item @code{binary-download}
|
|
@tab @code{X}
|
|
@tab @code{load}, @code{set}
|
|
|
|
@item @code{read-aux-vector}
|
|
@tab @code{qXfer:auxv:read}
|
|
@tab @code{info auxv}
|
|
|
|
@item @code{symbol-lookup}
|
|
@tab @code{qSymbol}
|
|
@tab Detecting multiple threads
|
|
|
|
@item @code{attach}
|
|
@tab @code{vAttach}
|
|
@tab @code{attach}
|
|
|
|
@item @code{verbose-resume}
|
|
@tab @code{vCont}
|
|
@tab Stepping or resuming multiple threads
|
|
|
|
@item @code{run}
|
|
@tab @code{vRun}
|
|
@tab @code{run}
|
|
|
|
@item @code{software-breakpoint}
|
|
@tab @code{Z0}
|
|
@tab @code{break}
|
|
|
|
@item @code{hardware-breakpoint}
|
|
@tab @code{Z1}
|
|
@tab @code{hbreak}
|
|
|
|
@item @code{write-watchpoint}
|
|
@tab @code{Z2}
|
|
@tab @code{watch}
|
|
|
|
@item @code{read-watchpoint}
|
|
@tab @code{Z3}
|
|
@tab @code{rwatch}
|
|
|
|
@item @code{access-watchpoint}
|
|
@tab @code{Z4}
|
|
@tab @code{awatch}
|
|
|
|
@item @code{target-features}
|
|
@tab @code{qXfer:features:read}
|
|
@tab @code{set architecture}
|
|
|
|
@item @code{library-info}
|
|
@tab @code{qXfer:libraries:read}
|
|
@tab @code{info sharedlibrary}
|
|
|
|
@item @code{memory-map}
|
|
@tab @code{qXfer:memory-map:read}
|
|
@tab @code{info mem}
|
|
|
|
@item @code{read-sdata-object}
|
|
@tab @code{qXfer:sdata:read}
|
|
@tab @code{print $_sdata}
|
|
|
|
@item @code{read-spu-object}
|
|
@tab @code{qXfer:spu:read}
|
|
@tab @code{info spu}
|
|
|
|
@item @code{write-spu-object}
|
|
@tab @code{qXfer:spu:write}
|
|
@tab @code{info spu}
|
|
|
|
@item @code{read-siginfo-object}
|
|
@tab @code{qXfer:siginfo:read}
|
|
@tab @code{print $_siginfo}
|
|
|
|
@item @code{write-siginfo-object}
|
|
@tab @code{qXfer:siginfo:write}
|
|
@tab @code{set $_siginfo}
|
|
|
|
@item @code{threads}
|
|
@tab @code{qXfer:threads:read}
|
|
@tab @code{info threads}
|
|
|
|
@item @code{get-thread-local-@*storage-address}
|
|
@tab @code{qGetTLSAddr}
|
|
@tab Displaying @code{__thread} variables
|
|
|
|
@item @code{get-thread-information-block-address}
|
|
@tab @code{qGetTIBAddr}
|
|
@tab Display MS-Windows Thread Information Block.
|
|
|
|
@item @code{search-memory}
|
|
@tab @code{qSearch:memory}
|
|
@tab @code{find}
|
|
|
|
@item @code{supported-packets}
|
|
@tab @code{qSupported}
|
|
@tab Remote communications parameters
|
|
|
|
@item @code{pass-signals}
|
|
@tab @code{QPassSignals}
|
|
@tab @code{handle @var{signal}}
|
|
|
|
@item @code{program-signals}
|
|
@tab @code{QProgramSignals}
|
|
@tab @code{handle @var{signal}}
|
|
|
|
@item @code{hostio-close-packet}
|
|
@tab @code{vFile:close}
|
|
@tab @code{remote get}, @code{remote put}
|
|
|
|
@item @code{hostio-open-packet}
|
|
@tab @code{vFile:open}
|
|
@tab @code{remote get}, @code{remote put}
|
|
|
|
@item @code{hostio-pread-packet}
|
|
@tab @code{vFile:pread}
|
|
@tab @code{remote get}, @code{remote put}
|
|
|
|
@item @code{hostio-pwrite-packet}
|
|
@tab @code{vFile:pwrite}
|
|
@tab @code{remote get}, @code{remote put}
|
|
|
|
@item @code{hostio-unlink-packet}
|
|
@tab @code{vFile:unlink}
|
|
@tab @code{remote delete}
|
|
|
|
@item @code{hostio-readlink-packet}
|
|
@tab @code{vFile:readlink}
|
|
@tab Host I/O
|
|
|
|
@item @code{noack-packet}
|
|
@tab @code{QStartNoAckMode}
|
|
@tab Packet acknowledgment
|
|
|
|
@item @code{osdata}
|
|
@tab @code{qXfer:osdata:read}
|
|
@tab @code{info os}
|
|
|
|
@item @code{query-attached}
|
|
@tab @code{qAttached}
|
|
@tab Querying remote process attach state.
|
|
|
|
@item @code{traceframe-info}
|
|
@tab @code{qXfer:traceframe-info:read}
|
|
@tab Traceframe info
|
|
|
|
@item @code{install-in-trace}
|
|
@tab @code{InstallInTrace}
|
|
@tab Install tracepoint in tracing
|
|
|
|
@item @code{disable-randomization}
|
|
@tab @code{QDisableRandomization}
|
|
@tab @code{set disable-randomization}
|
|
|
|
@item @code{conditional-breakpoints-packet}
|
|
@tab @code{Z0 and Z1}
|
|
@tab @code{Support for target-side breakpoint condition evaluation}
|
|
@end multitable
|
|
|
|
@node Remote Stub
|
|
@section Implementing a Remote Stub
|
|
|
|
@cindex debugging stub, example
|
|
@cindex remote stub, example
|
|
@cindex stub example, remote debugging
|
|
The stub files provided with @value{GDBN} implement the target side of the
|
|
communication protocol, and the @value{GDBN} side is implemented in the
|
|
@value{GDBN} source file @file{remote.c}. Normally, you can simply allow
|
|
these subroutines to communicate, and ignore the details. (If you're
|
|
implementing your own stub file, you can still ignore the details: start
|
|
with one of the existing stub files. @file{sparc-stub.c} is the best
|
|
organized, and therefore the easiest to read.)
|
|
|
|
@cindex remote serial debugging, overview
|
|
To debug a program running on another machine (the debugging
|
|
@dfn{target} machine), you must first arrange for all the usual
|
|
prerequisites for the program to run by itself. For example, for a C
|
|
program, you need:
|
|
|
|
@enumerate
|
|
@item
|
|
A startup routine to set up the C runtime environment; these usually
|
|
have a name like @file{crt0}. The startup routine may be supplied by
|
|
your hardware supplier, or you may have to write your own.
|
|
|
|
@item
|
|
A C subroutine library to support your program's
|
|
subroutine calls, notably managing input and output.
|
|
|
|
@item
|
|
A way of getting your program to the other machine---for example, a
|
|
download program. These are often supplied by the hardware
|
|
manufacturer, but you may have to write your own from hardware
|
|
documentation.
|
|
@end enumerate
|
|
|
|
The next step is to arrange for your program to use a serial port to
|
|
communicate with the machine where @value{GDBN} is running (the @dfn{host}
|
|
machine). In general terms, the scheme looks like this:
|
|
|
|
@table @emph
|
|
@item On the host,
|
|
@value{GDBN} already understands how to use this protocol; when everything
|
|
else is set up, you can simply use the @samp{target remote} command
|
|
(@pxref{Targets,,Specifying a Debugging Target}).
|
|
|
|
@item On the target,
|
|
you must link with your program a few special-purpose subroutines that
|
|
implement the @value{GDBN} remote serial protocol. The file containing these
|
|
subroutines is called a @dfn{debugging stub}.
|
|
|
|
On certain remote targets, you can use an auxiliary program
|
|
@code{gdbserver} instead of linking a stub into your program.
|
|
@xref{Server,,Using the @code{gdbserver} Program}, for details.
|
|
@end table
|
|
|
|
The debugging stub is specific to the architecture of the remote
|
|
machine; for example, use @file{sparc-stub.c} to debug programs on
|
|
@sc{sparc} boards.
|
|
|
|
@cindex remote serial stub list
|
|
These working remote stubs are distributed with @value{GDBN}:
|
|
|
|
@table @code
|
|
|
|
@item i386-stub.c
|
|
@cindex @file{i386-stub.c}
|
|
@cindex Intel
|
|
@cindex i386
|
|
For Intel 386 and compatible architectures.
|
|
|
|
@item m68k-stub.c
|
|
@cindex @file{m68k-stub.c}
|
|
@cindex Motorola 680x0
|
|
@cindex m680x0
|
|
For Motorola 680x0 architectures.
|
|
|
|
@item sh-stub.c
|
|
@cindex @file{sh-stub.c}
|
|
@cindex Renesas
|
|
@cindex SH
|
|
For Renesas SH architectures.
|
|
|
|
@item sparc-stub.c
|
|
@cindex @file{sparc-stub.c}
|
|
@cindex Sparc
|
|
For @sc{sparc} architectures.
|
|
|
|
@item sparcl-stub.c
|
|
@cindex @file{sparcl-stub.c}
|
|
@cindex Fujitsu
|
|
@cindex SparcLite
|
|
For Fujitsu @sc{sparclite} architectures.
|
|
|
|
@end table
|
|
|
|
The @file{README} file in the @value{GDBN} distribution may list other
|
|
recently added stubs.
|
|
|
|
@menu
|
|
* Stub Contents:: What the stub can do for you
|
|
* Bootstrapping:: What you must do for the stub
|
|
* Debug Session:: Putting it all together
|
|
@end menu
|
|
|
|
@node Stub Contents
|
|
@subsection What the Stub Can Do for You
|
|
|
|
@cindex remote serial stub
|
|
The debugging stub for your architecture supplies these three
|
|
subroutines:
|
|
|
|
@table @code
|
|
@item set_debug_traps
|
|
@findex set_debug_traps
|
|
@cindex remote serial stub, initialization
|
|
This routine arranges for @code{handle_exception} to run when your
|
|
program stops. You must call this subroutine explicitly in your
|
|
program's startup code.
|
|
|
|
@item handle_exception
|
|
@findex handle_exception
|
|
@cindex remote serial stub, main routine
|
|
This is the central workhorse, but your program never calls it
|
|
explicitly---the setup code arranges for @code{handle_exception} to
|
|
run when a trap is triggered.
|
|
|
|
@code{handle_exception} takes control when your program stops during
|
|
execution (for example, on a breakpoint), and mediates communications
|
|
with @value{GDBN} on the host machine. This is where the communications
|
|
protocol is implemented; @code{handle_exception} acts as the @value{GDBN}
|
|
representative on the target machine. It begins by sending summary
|
|
information on the state of your program, then continues to execute,
|
|
retrieving and transmitting any information @value{GDBN} needs, until you
|
|
execute a @value{GDBN} command that makes your program resume; at that point,
|
|
@code{handle_exception} returns control to your own code on the target
|
|
machine.
|
|
|
|
@item breakpoint
|
|
@cindex @code{breakpoint} subroutine, remote
|
|
Use this auxiliary subroutine to make your program contain a
|
|
breakpoint. Depending on the particular situation, this may be the only
|
|
way for @value{GDBN} to get control. For instance, if your target
|
|
machine has some sort of interrupt button, you won't need to call this;
|
|
pressing the interrupt button transfers control to
|
|
@code{handle_exception}---in effect, to @value{GDBN}. On some machines,
|
|
simply receiving characters on the serial port may also trigger a trap;
|
|
again, in that situation, you don't need to call @code{breakpoint} from
|
|
your own program---simply running @samp{target remote} from the host
|
|
@value{GDBN} session gets control.
|
|
|
|
Call @code{breakpoint} if none of these is true, or if you simply want
|
|
to make certain your program stops at a predetermined point for the
|
|
start of your debugging session.
|
|
@end table
|
|
|
|
@node Bootstrapping
|
|
@subsection What You Must Do for the Stub
|
|
|
|
@cindex remote stub, support routines
|
|
The debugging stubs that come with @value{GDBN} are set up for a particular
|
|
chip architecture, but they have no information about the rest of your
|
|
debugging target machine.
|
|
|
|
First of all you need to tell the stub how to communicate with the
|
|
serial port.
|
|
|
|
@table @code
|
|
@item int getDebugChar()
|
|
@findex getDebugChar
|
|
Write this subroutine to read a single character from the serial port.
|
|
It may be identical to @code{getchar} for your target system; a
|
|
different name is used to allow you to distinguish the two if you wish.
|
|
|
|
@item void putDebugChar(int)
|
|
@findex putDebugChar
|
|
Write this subroutine to write a single character to the serial port.
|
|
It may be identical to @code{putchar} for your target system; a
|
|
different name is used to allow you to distinguish the two if you wish.
|
|
@end table
|
|
|
|
@cindex control C, and remote debugging
|
|
@cindex interrupting remote targets
|
|
If you want @value{GDBN} to be able to stop your program while it is
|
|
running, you need to use an interrupt-driven serial driver, and arrange
|
|
for it to stop when it receives a @code{^C} (@samp{\003}, the control-C
|
|
character). That is the character which @value{GDBN} uses to tell the
|
|
remote system to stop.
|
|
|
|
Getting the debugging target to return the proper status to @value{GDBN}
|
|
probably requires changes to the standard stub; one quick and dirty way
|
|
is to just execute a breakpoint instruction (the ``dirty'' part is that
|
|
@value{GDBN} reports a @code{SIGTRAP} instead of a @code{SIGINT}).
|
|
|
|
Other routines you need to supply are:
|
|
|
|
@table @code
|
|
@item void exceptionHandler (int @var{exception_number}, void *@var{exception_address})
|
|
@findex exceptionHandler
|
|
Write this function to install @var{exception_address} in the exception
|
|
handling tables. You need to do this because the stub does not have any
|
|
way of knowing what the exception handling tables on your target system
|
|
are like (for example, the processor's table might be in @sc{rom},
|
|
containing entries which point to a table in @sc{ram}).
|
|
@var{exception_number} is the exception number which should be changed;
|
|
its meaning is architecture-dependent (for example, different numbers
|
|
might represent divide by zero, misaligned access, etc). When this
|
|
exception occurs, control should be transferred directly to
|
|
@var{exception_address}, and the processor state (stack, registers,
|
|
and so on) should be just as it is when a processor exception occurs. So if
|
|
you want to use a jump instruction to reach @var{exception_address}, it
|
|
should be a simple jump, not a jump to subroutine.
|
|
|
|
For the 386, @var{exception_address} should be installed as an interrupt
|
|
gate so that interrupts are masked while the handler runs. The gate
|
|
should be at privilege level 0 (the most privileged level). The
|
|
@sc{sparc} and 68k stubs are able to mask interrupts themselves without
|
|
help from @code{exceptionHandler}.
|
|
|
|
@item void flush_i_cache()
|
|
@findex flush_i_cache
|
|
On @sc{sparc} and @sc{sparclite} only, write this subroutine to flush the
|
|
instruction cache, if any, on your target machine. If there is no
|
|
instruction cache, this subroutine may be a no-op.
|
|
|
|
On target machines that have instruction caches, @value{GDBN} requires this
|
|
function to make certain that the state of your program is stable.
|
|
@end table
|
|
|
|
@noindent
|
|
You must also make sure this library routine is available:
|
|
|
|
@table @code
|
|
@item void *memset(void *, int, int)
|
|
@findex memset
|
|
This is the standard library function @code{memset} that sets an area of
|
|
memory to a known value. If you have one of the free versions of
|
|
@code{libc.a}, @code{memset} can be found there; otherwise, you must
|
|
either obtain it from your hardware manufacturer, or write your own.
|
|
@end table
|
|
|
|
If you do not use the GNU C compiler, you may need other standard
|
|
library subroutines as well; this varies from one stub to another,
|
|
but in general the stubs are likely to use any of the common library
|
|
subroutines which @code{@value{NGCC}} generates as inline code.
|
|
|
|
|
|
@node Debug Session
|
|
@subsection Putting it All Together
|
|
|
|
@cindex remote serial debugging summary
|
|
In summary, when your program is ready to debug, you must follow these
|
|
steps.
|
|
|
|
@enumerate
|
|
@item
|
|
Make sure you have defined the supporting low-level routines
|
|
(@pxref{Bootstrapping,,What You Must Do for the Stub}):
|
|
@display
|
|
@code{getDebugChar}, @code{putDebugChar},
|
|
@code{flush_i_cache}, @code{memset}, @code{exceptionHandler}.
|
|
@end display
|
|
|
|
@item
|
|
Insert these lines in your program's startup code, before the main
|
|
procedure is called:
|
|
|
|
@smallexample
|
|
set_debug_traps();
|
|
breakpoint();
|
|
@end smallexample
|
|
|
|
On some machines, when a breakpoint trap is raised, the hardware
|
|
automatically makes the PC point to the instruction after the
|
|
breakpoint. If your machine doesn't do that, you may need to adjust
|
|
@code{handle_exception} to arrange for it to return to the instruction
|
|
after the breakpoint on this first invocation, so that your program
|
|
doesn't keep hitting the initial breakpoint instead of making
|
|
progress.
|
|
|
|
@item
|
|
For the 680x0 stub only, you need to provide a variable called
|
|
@code{exceptionHook}. Normally you just use:
|
|
|
|
@smallexample
|
|
void (*exceptionHook)() = 0;
|
|
@end smallexample
|
|
|
|
@noindent
|
|
but if before calling @code{set_debug_traps}, you set it to point to a
|
|
function in your program, that function is called when
|
|
@code{@value{GDBN}} continues after stopping on a trap (for example, bus
|
|
error). The function indicated by @code{exceptionHook} is called with
|
|
one parameter: an @code{int} which is the exception number.
|
|
|
|
@item
|
|
Compile and link together: your program, the @value{GDBN} debugging stub for
|
|
your target architecture, and the supporting subroutines.
|
|
|
|
@item
|
|
Make sure you have a serial connection between your target machine and
|
|
the @value{GDBN} host, and identify the serial port on the host.
|
|
|
|
@item
|
|
@c The "remote" target now provides a `load' command, so we should
|
|
@c document that. FIXME.
|
|
Download your program to your target machine (or get it there by
|
|
whatever means the manufacturer provides), and start it.
|
|
|
|
@item
|
|
Start @value{GDBN} on the host, and connect to the target
|
|
(@pxref{Connecting,,Connecting to a Remote Target}).
|
|
|
|
@end enumerate
|
|
|
|
@node Configurations
|
|
@chapter Configuration-Specific Information
|
|
|
|
While nearly all @value{GDBN} commands are available for all native and
|
|
cross versions of the debugger, there are some exceptions. This chapter
|
|
describes things that are only available in certain configurations.
|
|
|
|
There are three major categories of configurations: native
|
|
configurations, where the host and target are the same, embedded
|
|
operating system configurations, which are usually the same for several
|
|
different processor architectures, and bare embedded processors, which
|
|
are quite different from each other.
|
|
|
|
@menu
|
|
* Native::
|
|
* Embedded OS::
|
|
* Embedded Processors::
|
|
* Architectures::
|
|
@end menu
|
|
|
|
@node Native
|
|
@section Native
|
|
|
|
This section describes details specific to particular native
|
|
configurations.
|
|
|
|
@menu
|
|
* HP-UX:: HP-UX
|
|
* BSD libkvm Interface:: Debugging BSD kernel memory images
|
|
* SVR4 Process Information:: SVR4 process information
|
|
* DJGPP Native:: Features specific to the DJGPP port
|
|
* Cygwin Native:: Features specific to the Cygwin port
|
|
* Hurd Native:: Features specific to @sc{gnu} Hurd
|
|
* Darwin:: Features specific to Darwin
|
|
@end menu
|
|
|
|
@node HP-UX
|
|
@subsection HP-UX
|
|
|
|
On HP-UX systems, if you refer to a function or variable name that
|
|
begins with a dollar sign, @value{GDBN} searches for a user or system
|
|
name first, before it searches for a convenience variable.
|
|
|
|
|
|
@node BSD libkvm Interface
|
|
@subsection BSD libkvm Interface
|
|
|
|
@cindex libkvm
|
|
@cindex kernel memory image
|
|
@cindex kernel crash dump
|
|
|
|
BSD-derived systems (FreeBSD/NetBSD/OpenBSD) have a kernel memory
|
|
interface that provides a uniform interface for accessing kernel virtual
|
|
memory images, including live systems and crash dumps. @value{GDBN}
|
|
uses this interface to allow you to debug live kernels and kernel crash
|
|
dumps on many native BSD configurations. This is implemented as a
|
|
special @code{kvm} debugging target. For debugging a live system, load
|
|
the currently running kernel into @value{GDBN} and connect to the
|
|
@code{kvm} target:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) @b{target kvm}
|
|
@end smallexample
|
|
|
|
For debugging crash dumps, provide the file name of the crash dump as an
|
|
argument:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) @b{target kvm /var/crash/bsd.0}
|
|
@end smallexample
|
|
|
|
Once connected to the @code{kvm} target, the following commands are
|
|
available:
|
|
|
|
@table @code
|
|
@kindex kvm
|
|
@item kvm pcb
|
|
Set current context from the @dfn{Process Control Block} (PCB) address.
|
|
|
|
@item kvm proc
|
|
Set current context from proc address. This command isn't available on
|
|
modern FreeBSD systems.
|
|
@end table
|
|
|
|
@node SVR4 Process Information
|
|
@subsection SVR4 Process Information
|
|
@cindex /proc
|
|
@cindex examine process image
|
|
@cindex process info via @file{/proc}
|
|
|
|
Many versions of SVR4 and compatible systems provide a facility called
|
|
@samp{/proc} that can be used to examine the image of a running
|
|
process using file-system subroutines. If @value{GDBN} is configured
|
|
for an operating system with this facility, the command @code{info
|
|
proc} is available to report information about the process running
|
|
your program, or about any process running on your system. @code{info
|
|
proc} works only on SVR4 systems that include the @code{procfs} code.
|
|
This includes, as of this writing, @sc{gnu}/Linux, OSF/1 (Digital
|
|
Unix), Solaris, Irix, and Unixware, but not HP-UX, for example.
|
|
|
|
@table @code
|
|
@kindex info proc
|
|
@cindex process ID
|
|
@item info proc
|
|
@itemx info proc @var{process-id}
|
|
Summarize available information about any running process. If a
|
|
process ID is specified by @var{process-id}, display information about
|
|
that process; otherwise display information about the program being
|
|
debugged. The summary includes the debugged process ID, the command
|
|
line used to invoke it, its current working directory, and its
|
|
executable file's absolute file name.
|
|
|
|
On some systems, @var{process-id} can be of the form
|
|
@samp{[@var{pid}]/@var{tid}} which specifies a certain thread ID
|
|
within a process. If the optional @var{pid} part is missing, it means
|
|
a thread from the process being debugged (the leading @samp{/} still
|
|
needs to be present, or else @value{GDBN} will interpret the number as
|
|
a process ID rather than a thread ID).
|
|
|
|
@item info proc mappings
|
|
@cindex memory address space mappings
|
|
Report the memory address space ranges accessible in the program, with
|
|
information on whether the process has read, write, or execute access
|
|
rights to each range. On @sc{gnu}/Linux systems, each memory range
|
|
includes the object file which is mapped to that range, instead of the
|
|
memory access rights to that range.
|
|
|
|
@item info proc stat
|
|
@itemx info proc status
|
|
@cindex process detailed status information
|
|
These subcommands are specific to @sc{gnu}/Linux systems. They show
|
|
the process-related information, including the user ID and group ID;
|
|
how many threads are there in the process; its virtual memory usage;
|
|
the signals that are pending, blocked, and ignored; its TTY; its
|
|
consumption of system and user time; its stack size; its @samp{nice}
|
|
value; etc. For more information, see the @samp{proc} man page
|
|
(type @kbd{man 5 proc} from your shell prompt).
|
|
|
|
@item info proc all
|
|
Show all the information about the process described under all of the
|
|
above @code{info proc} subcommands.
|
|
|
|
@ignore
|
|
@comment These sub-options of 'info proc' were not included when
|
|
@comment procfs.c was re-written. Keep their descriptions around
|
|
@comment against the day when someone finds the time to put them back in.
|
|
@kindex info proc times
|
|
@item info proc times
|
|
Starting time, user CPU time, and system CPU time for your program and
|
|
its children.
|
|
|
|
@kindex info proc id
|
|
@item info proc id
|
|
Report on the process IDs related to your program: its own process ID,
|
|
the ID of its parent, the process group ID, and the session ID.
|
|
@end ignore
|
|
|
|
@item set procfs-trace
|
|
@kindex set procfs-trace
|
|
@cindex @code{procfs} API calls
|
|
This command enables and disables tracing of @code{procfs} API calls.
|
|
|
|
@item show procfs-trace
|
|
@kindex show procfs-trace
|
|
Show the current state of @code{procfs} API call tracing.
|
|
|
|
@item set procfs-file @var{file}
|
|
@kindex set procfs-file
|
|
Tell @value{GDBN} to write @code{procfs} API trace to the named
|
|
@var{file}. @value{GDBN} appends the trace info to the previous
|
|
contents of the file. The default is to display the trace on the
|
|
standard output.
|
|
|
|
@item show procfs-file
|
|
@kindex show procfs-file
|
|
Show the file to which @code{procfs} API trace is written.
|
|
|
|
@item proc-trace-entry
|
|
@itemx proc-trace-exit
|
|
@itemx proc-untrace-entry
|
|
@itemx proc-untrace-exit
|
|
@kindex proc-trace-entry
|
|
@kindex proc-trace-exit
|
|
@kindex proc-untrace-entry
|
|
@kindex proc-untrace-exit
|
|
These commands enable and disable tracing of entries into and exits
|
|
from the @code{syscall} interface.
|
|
|
|
@item info pidlist
|
|
@kindex info pidlist
|
|
@cindex process list, QNX Neutrino
|
|
For QNX Neutrino only, this command displays the list of all the
|
|
processes and all the threads within each process.
|
|
|
|
@item info meminfo
|
|
@kindex info meminfo
|
|
@cindex mapinfo list, QNX Neutrino
|
|
For QNX Neutrino only, this command displays the list of all mapinfos.
|
|
@end table
|
|
|
|
@node DJGPP Native
|
|
@subsection Features for Debugging @sc{djgpp} Programs
|
|
@cindex @sc{djgpp} debugging
|
|
@cindex native @sc{djgpp} debugging
|
|
@cindex MS-DOS-specific commands
|
|
|
|
@cindex DPMI
|
|
@sc{djgpp} is a port of the @sc{gnu} development tools to MS-DOS and
|
|
MS-Windows. @sc{djgpp} programs are 32-bit protected-mode programs
|
|
that use the @dfn{DPMI} (DOS Protected-Mode Interface) API to run on
|
|
top of real-mode DOS systems and their emulations.
|
|
|
|
@value{GDBN} supports native debugging of @sc{djgpp} programs, and
|
|
defines a few commands specific to the @sc{djgpp} port. This
|
|
subsection describes those commands.
|
|
|
|
@table @code
|
|
@kindex info dos
|
|
@item info dos
|
|
This is a prefix of @sc{djgpp}-specific commands which print
|
|
information about the target system and important OS structures.
|
|
|
|
@kindex sysinfo
|
|
@cindex MS-DOS system info
|
|
@cindex free memory information (MS-DOS)
|
|
@item info dos sysinfo
|
|
This command displays assorted information about the underlying
|
|
platform: the CPU type and features, the OS version and flavor, the
|
|
DPMI version, and the available conventional and DPMI memory.
|
|
|
|
@cindex GDT
|
|
@cindex LDT
|
|
@cindex IDT
|
|
@cindex segment descriptor tables
|
|
@cindex descriptor tables display
|
|
@item info dos gdt
|
|
@itemx info dos ldt
|
|
@itemx info dos idt
|
|
These 3 commands display entries from, respectively, Global, Local,
|
|
and Interrupt Descriptor Tables (GDT, LDT, and IDT). The descriptor
|
|
tables are data structures which store a descriptor for each segment
|
|
that is currently in use. The segment's selector is an index into a
|
|
descriptor table; the table entry for that index holds the
|
|
descriptor's base address and limit, and its attributes and access
|
|
rights.
|
|
|
|
A typical @sc{djgpp} program uses 3 segments: a code segment, a data
|
|
segment (used for both data and the stack), and a DOS segment (which
|
|
allows access to DOS/BIOS data structures and absolute addresses in
|
|
conventional memory). However, the DPMI host will usually define
|
|
additional segments in order to support the DPMI environment.
|
|
|
|
@cindex garbled pointers
|
|
These commands allow to display entries from the descriptor tables.
|
|
Without an argument, all entries from the specified table are
|
|
displayed. An argument, which should be an integer expression, means
|
|
display a single entry whose index is given by the argument. For
|
|
example, here's a convenient way to display information about the
|
|
debugged program's data segment:
|
|
|
|
@smallexample
|
|
@exdent @code{(@value{GDBP}) info dos ldt $ds}
|
|
@exdent @code{0x13f: base=0x11970000 limit=0x0009ffff 32-Bit Data (Read/Write, Exp-up)}
|
|
@end smallexample
|
|
|
|
@noindent
|
|
This comes in handy when you want to see whether a pointer is outside
|
|
the data segment's limit (i.e.@: @dfn{garbled}).
|
|
|
|
@cindex page tables display (MS-DOS)
|
|
@item info dos pde
|
|
@itemx info dos pte
|
|
These two commands display entries from, respectively, the Page
|
|
Directory and the Page Tables. Page Directories and Page Tables are
|
|
data structures which control how virtual memory addresses are mapped
|
|
into physical addresses. A Page Table includes an entry for every
|
|
page of memory that is mapped into the program's address space; there
|
|
may be several Page Tables, each one holding up to 4096 entries. A
|
|
Page Directory has up to 4096 entries, one each for every Page Table
|
|
that is currently in use.
|
|
|
|
Without an argument, @kbd{info dos pde} displays the entire Page
|
|
Directory, and @kbd{info dos pte} displays all the entries in all of
|
|
the Page Tables. An argument, an integer expression, given to the
|
|
@kbd{info dos pde} command means display only that entry from the Page
|
|
Directory table. An argument given to the @kbd{info dos pte} command
|
|
means display entries from a single Page Table, the one pointed to by
|
|
the specified entry in the Page Directory.
|
|
|
|
@cindex direct memory access (DMA) on MS-DOS
|
|
These commands are useful when your program uses @dfn{DMA} (Direct
|
|
Memory Access), which needs physical addresses to program the DMA
|
|
controller.
|
|
|
|
These commands are supported only with some DPMI servers.
|
|
|
|
@cindex physical address from linear address
|
|
@item info dos address-pte @var{addr}
|
|
This command displays the Page Table entry for a specified linear
|
|
address. The argument @var{addr} is a linear address which should
|
|
already have the appropriate segment's base address added to it,
|
|
because this command accepts addresses which may belong to @emph{any}
|
|
segment. For example, here's how to display the Page Table entry for
|
|
the page where a variable @code{i} is stored:
|
|
|
|
@smallexample
|
|
@exdent @code{(@value{GDBP}) info dos address-pte __djgpp_base_address + (char *)&i}
|
|
@exdent @code{Page Table entry for address 0x11a00d30:}
|
|
@exdent @code{Base=0x02698000 Dirty Acc. Not-Cached Write-Back Usr Read-Write +0xd30}
|
|
@end smallexample
|
|
|
|
@noindent
|
|
This says that @code{i} is stored at offset @code{0xd30} from the page
|
|
whose physical base address is @code{0x02698000}, and shows all the
|
|
attributes of that page.
|
|
|
|
Note that you must cast the addresses of variables to a @code{char *},
|
|
since otherwise the value of @code{__djgpp_base_address}, the base
|
|
address of all variables and functions in a @sc{djgpp} program, will
|
|
be added using the rules of C pointer arithmetics: if @code{i} is
|
|
declared an @code{int}, @value{GDBN} will add 4 times the value of
|
|
@code{__djgpp_base_address} to the address of @code{i}.
|
|
|
|
Here's another example, it displays the Page Table entry for the
|
|
transfer buffer:
|
|
|
|
@smallexample
|
|
@exdent @code{(@value{GDBP}) info dos address-pte *((unsigned *)&_go32_info_block + 3)}
|
|
@exdent @code{Page Table entry for address 0x29110:}
|
|
@exdent @code{Base=0x00029000 Dirty Acc. Not-Cached Write-Back Usr Read-Write +0x110}
|
|
@end smallexample
|
|
|
|
@noindent
|
|
(The @code{+ 3} offset is because the transfer buffer's address is the
|
|
3rd member of the @code{_go32_info_block} structure.) The output
|
|
clearly shows that this DPMI server maps the addresses in conventional
|
|
memory 1:1, i.e.@: the physical (@code{0x00029000} + @code{0x110}) and
|
|
linear (@code{0x29110}) addresses are identical.
|
|
|
|
This command is supported only with some DPMI servers.
|
|
@end table
|
|
|
|
@cindex DOS serial data link, remote debugging
|
|
In addition to native debugging, the DJGPP port supports remote
|
|
debugging via a serial data link. The following commands are specific
|
|
to remote serial debugging in the DJGPP port of @value{GDBN}.
|
|
|
|
@table @code
|
|
@kindex set com1base
|
|
@kindex set com1irq
|
|
@kindex set com2base
|
|
@kindex set com2irq
|
|
@kindex set com3base
|
|
@kindex set com3irq
|
|
@kindex set com4base
|
|
@kindex set com4irq
|
|
@item set com1base @var{addr}
|
|
This command sets the base I/O port address of the @file{COM1} serial
|
|
port.
|
|
|
|
@item set com1irq @var{irq}
|
|
This command sets the @dfn{Interrupt Request} (@code{IRQ}) line to use
|
|
for the @file{COM1} serial port.
|
|
|
|
There are similar commands @samp{set com2base}, @samp{set com3irq},
|
|
etc.@: for setting the port address and the @code{IRQ} lines for the
|
|
other 3 COM ports.
|
|
|
|
@kindex show com1base
|
|
@kindex show com1irq
|
|
@kindex show com2base
|
|
@kindex show com2irq
|
|
@kindex show com3base
|
|
@kindex show com3irq
|
|
@kindex show com4base
|
|
@kindex show com4irq
|
|
The related commands @samp{show com1base}, @samp{show com1irq} etc.@:
|
|
display the current settings of the base address and the @code{IRQ}
|
|
lines used by the COM ports.
|
|
|
|
@item info serial
|
|
@kindex info serial
|
|
@cindex DOS serial port status
|
|
This command prints the status of the 4 DOS serial ports. For each
|
|
port, it prints whether it's active or not, its I/O base address and
|
|
IRQ number, whether it uses a 16550-style FIFO, its baudrate, and the
|
|
counts of various errors encountered so far.
|
|
@end table
|
|
|
|
|
|
@node Cygwin Native
|
|
@subsection Features for Debugging MS Windows PE Executables
|
|
@cindex MS Windows debugging
|
|
@cindex native Cygwin debugging
|
|
@cindex Cygwin-specific commands
|
|
|
|
@value{GDBN} supports native debugging of MS Windows programs, including
|
|
DLLs with and without symbolic debugging information.
|
|
|
|
@cindex Ctrl-BREAK, MS-Windows
|
|
@cindex interrupt debuggee on MS-Windows
|
|
MS-Windows programs that call @code{SetConsoleMode} to switch off the
|
|
special meaning of the @samp{Ctrl-C} keystroke cannot be interrupted
|
|
by typing @kbd{C-c}. For this reason, @value{GDBN} on MS-Windows
|
|
supports @kbd{C-@key{BREAK}} as an alternative interrupt key
|
|
sequence, which can be used to interrupt the debuggee even if it
|
|
ignores @kbd{C-c}.
|
|
|
|
There are various additional Cygwin-specific commands, described in
|
|
this section. Working with DLLs that have no debugging symbols is
|
|
described in @ref{Non-debug DLL Symbols}.
|
|
|
|
@table @code
|
|
@kindex info w32
|
|
@item info w32
|
|
This is a prefix of MS Windows-specific commands which print
|
|
information about the target system and important OS structures.
|
|
|
|
@item info w32 selector
|
|
This command displays information returned by
|
|
the Win32 API @code{GetThreadSelectorEntry} function.
|
|
It takes an optional argument that is evaluated to
|
|
a long value to give the information about this given selector.
|
|
Without argument, this command displays information
|
|
about the six segment registers.
|
|
|
|
@item info w32 thread-information-block
|
|
This command displays thread specific information stored in the
|
|
Thread Information Block (readable on the X86 CPU family using @code{$fs}
|
|
selector for 32-bit programs and @code{$gs} for 64-bit programs).
|
|
|
|
@kindex info dll
|
|
@item info dll
|
|
This is a Cygwin-specific alias of @code{info shared}.
|
|
|
|
@kindex dll-symbols
|
|
@item dll-symbols
|
|
This command loads symbols from a dll similarly to
|
|
add-sym command but without the need to specify a base address.
|
|
|
|
@kindex set cygwin-exceptions
|
|
@cindex debugging the Cygwin DLL
|
|
@cindex Cygwin DLL, debugging
|
|
@item set cygwin-exceptions @var{mode}
|
|
If @var{mode} is @code{on}, @value{GDBN} will break on exceptions that
|
|
happen inside the Cygwin DLL. If @var{mode} is @code{off},
|
|
@value{GDBN} will delay recognition of exceptions, and may ignore some
|
|
exceptions which seem to be caused by internal Cygwin DLL
|
|
``bookkeeping''. This option is meant primarily for debugging the
|
|
Cygwin DLL itself; the default value is @code{off} to avoid annoying
|
|
@value{GDBN} users with false @code{SIGSEGV} signals.
|
|
|
|
@kindex show cygwin-exceptions
|
|
@item show cygwin-exceptions
|
|
Displays whether @value{GDBN} will break on exceptions that happen
|
|
inside the Cygwin DLL itself.
|
|
|
|
@kindex set new-console
|
|
@item set new-console @var{mode}
|
|
If @var{mode} is @code{on} the debuggee will
|
|
be started in a new console on next start.
|
|
If @var{mode} is @code{off}, the debuggee will
|
|
be started in the same console as the debugger.
|
|
|
|
@kindex show new-console
|
|
@item show new-console
|
|
Displays whether a new console is used
|
|
when the debuggee is started.
|
|
|
|
@kindex set new-group
|
|
@item set new-group @var{mode}
|
|
This boolean value controls whether the debuggee should
|
|
start a new group or stay in the same group as the debugger.
|
|
This affects the way the Windows OS handles
|
|
@samp{Ctrl-C}.
|
|
|
|
@kindex show new-group
|
|
@item show new-group
|
|
Displays current value of new-group boolean.
|
|
|
|
@kindex set debugevents
|
|
@item set debugevents
|
|
This boolean value adds debug output concerning kernel events related
|
|
to the debuggee seen by the debugger. This includes events that
|
|
signal thread and process creation and exit, DLL loading and
|
|
unloading, console interrupts, and debugging messages produced by the
|
|
Windows @code{OutputDebugString} API call.
|
|
|
|
@kindex set debugexec
|
|
@item set debugexec
|
|
This boolean value adds debug output concerning execute events
|
|
(such as resume thread) seen by the debugger.
|
|
|
|
@kindex set debugexceptions
|
|
@item set debugexceptions
|
|
This boolean value adds debug output concerning exceptions in the
|
|
debuggee seen by the debugger.
|
|
|
|
@kindex set debugmemory
|
|
@item set debugmemory
|
|
This boolean value adds debug output concerning debuggee memory reads
|
|
and writes by the debugger.
|
|
|
|
@kindex set shell
|
|
@item set shell
|
|
This boolean values specifies whether the debuggee is called
|
|
via a shell or directly (default value is on).
|
|
|
|
@kindex show shell
|
|
@item show shell
|
|
Displays if the debuggee will be started with a shell.
|
|
|
|
@end table
|
|
|
|
@menu
|
|
* Non-debug DLL Symbols:: Support for DLLs without debugging symbols
|
|
@end menu
|
|
|
|
@node Non-debug DLL Symbols
|
|
@subsubsection Support for DLLs without Debugging Symbols
|
|
@cindex DLLs with no debugging symbols
|
|
@cindex Minimal symbols and DLLs
|
|
|
|
Very often on windows, some of the DLLs that your program relies on do
|
|
not include symbolic debugging information (for example,
|
|
@file{kernel32.dll}). When @value{GDBN} doesn't recognize any debugging
|
|
symbols in a DLL, it relies on the minimal amount of symbolic
|
|
information contained in the DLL's export table. This section
|
|
describes working with such symbols, known internally to @value{GDBN} as
|
|
``minimal symbols''.
|
|
|
|
Note that before the debugged program has started execution, no DLLs
|
|
will have been loaded. The easiest way around this problem is simply to
|
|
start the program --- either by setting a breakpoint or letting the
|
|
program run once to completion. It is also possible to force
|
|
@value{GDBN} to load a particular DLL before starting the executable ---
|
|
see the shared library information in @ref{Files}, or the
|
|
@code{dll-symbols} command in @ref{Cygwin Native}. Currently,
|
|
explicitly loading symbols from a DLL with no debugging information will
|
|
cause the symbol names to be duplicated in @value{GDBN}'s lookup table,
|
|
which may adversely affect symbol lookup performance.
|
|
|
|
@subsubsection DLL Name Prefixes
|
|
|
|
In keeping with the naming conventions used by the Microsoft debugging
|
|
tools, DLL export symbols are made available with a prefix based on the
|
|
DLL name, for instance @code{KERNEL32!CreateFileA}. The plain name is
|
|
also entered into the symbol table, so @code{CreateFileA} is often
|
|
sufficient. In some cases there will be name clashes within a program
|
|
(particularly if the executable itself includes full debugging symbols)
|
|
necessitating the use of the fully qualified name when referring to the
|
|
contents of the DLL. Use single-quotes around the name to avoid the
|
|
exclamation mark (``!'') being interpreted as a language operator.
|
|
|
|
Note that the internal name of the DLL may be all upper-case, even
|
|
though the file name of the DLL is lower-case, or vice-versa. Since
|
|
symbols within @value{GDBN} are @emph{case-sensitive} this may cause
|
|
some confusion. If in doubt, try the @code{info functions} and
|
|
@code{info variables} commands or even @code{maint print msymbols}
|
|
(@pxref{Symbols}). Here's an example:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) info function CreateFileA
|
|
All functions matching regular expression "CreateFileA":
|
|
|
|
Non-debugging symbols:
|
|
0x77e885f4 CreateFileA
|
|
0x77e885f4 KERNEL32!CreateFileA
|
|
@end smallexample
|
|
|
|
@smallexample
|
|
(@value{GDBP}) info function !
|
|
All functions matching regular expression "!":
|
|
|
|
Non-debugging symbols:
|
|
0x6100114c cygwin1!__assert
|
|
0x61004034 cygwin1!_dll_crt0@@0
|
|
0x61004240 cygwin1!dll_crt0(per_process *)
|
|
[etc...]
|
|
@end smallexample
|
|
|
|
@subsubsection Working with Minimal Symbols
|
|
|
|
Symbols extracted from a DLL's export table do not contain very much
|
|
type information. All that @value{GDBN} can do is guess whether a symbol
|
|
refers to a function or variable depending on the linker section that
|
|
contains the symbol. Also note that the actual contents of the memory
|
|
contained in a DLL are not available unless the program is running. This
|
|
means that you cannot examine the contents of a variable or disassemble
|
|
a function within a DLL without a running program.
|
|
|
|
Variables are generally treated as pointers and dereferenced
|
|
automatically. For this reason, it is often necessary to prefix a
|
|
variable name with the address-of operator (``&'') and provide explicit
|
|
type information in the command. Here's an example of the type of
|
|
problem:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) print 'cygwin1!__argv'
|
|
$1 = 268572168
|
|
@end smallexample
|
|
|
|
@smallexample
|
|
(@value{GDBP}) x 'cygwin1!__argv'
|
|
0x10021610: "\230y\""
|
|
@end smallexample
|
|
|
|
And two possible solutions:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) print ((char **)'cygwin1!__argv')[0]
|
|
$2 = 0x22fd98 "/cygdrive/c/mydirectory/myprogram"
|
|
@end smallexample
|
|
|
|
@smallexample
|
|
(@value{GDBP}) x/2x &'cygwin1!__argv'
|
|
0x610c0aa8 <cygwin1!__argv>: 0x10021608 0x00000000
|
|
(@value{GDBP}) x/x 0x10021608
|
|
0x10021608: 0x0022fd98
|
|
(@value{GDBP}) x/s 0x0022fd98
|
|
0x22fd98: "/cygdrive/c/mydirectory/myprogram"
|
|
@end smallexample
|
|
|
|
Setting a break point within a DLL is possible even before the program
|
|
starts execution. However, under these circumstances, @value{GDBN} can't
|
|
examine the initial instructions of the function in order to skip the
|
|
function's frame set-up code. You can work around this by using ``*&''
|
|
to set the breakpoint at a raw memory address:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) break *&'python22!PyOS_Readline'
|
|
Breakpoint 1 at 0x1e04eff0
|
|
@end smallexample
|
|
|
|
The author of these extensions is not entirely convinced that setting a
|
|
break point within a shared DLL like @file{kernel32.dll} is completely
|
|
safe.
|
|
|
|
@node Hurd Native
|
|
@subsection Commands Specific to @sc{gnu} Hurd Systems
|
|
@cindex @sc{gnu} Hurd debugging
|
|
|
|
This subsection describes @value{GDBN} commands specific to the
|
|
@sc{gnu} Hurd native debugging.
|
|
|
|
@table @code
|
|
@item set signals
|
|
@itemx set sigs
|
|
@kindex set signals@r{, Hurd command}
|
|
@kindex set sigs@r{, Hurd command}
|
|
This command toggles the state of inferior signal interception by
|
|
@value{GDBN}. Mach exceptions, such as breakpoint traps, are not
|
|
affected by this command. @code{sigs} is a shorthand alias for
|
|
@code{signals}.
|
|
|
|
@item show signals
|
|
@itemx show sigs
|
|
@kindex show signals@r{, Hurd command}
|
|
@kindex show sigs@r{, Hurd command}
|
|
Show the current state of intercepting inferior's signals.
|
|
|
|
@item set signal-thread
|
|
@itemx set sigthread
|
|
@kindex set signal-thread
|
|
@kindex set sigthread
|
|
This command tells @value{GDBN} which thread is the @code{libc} signal
|
|
thread. That thread is run when a signal is delivered to a running
|
|
process. @code{set sigthread} is the shorthand alias of @code{set
|
|
signal-thread}.
|
|
|
|
@item show signal-thread
|
|
@itemx show sigthread
|
|
@kindex show signal-thread
|
|
@kindex show sigthread
|
|
These two commands show which thread will run when the inferior is
|
|
delivered a signal.
|
|
|
|
@item set stopped
|
|
@kindex set stopped@r{, Hurd command}
|
|
This commands tells @value{GDBN} that the inferior process is stopped,
|
|
as with the @code{SIGSTOP} signal. The stopped process can be
|
|
continued by delivering a signal to it.
|
|
|
|
@item show stopped
|
|
@kindex show stopped@r{, Hurd command}
|
|
This command shows whether @value{GDBN} thinks the debuggee is
|
|
stopped.
|
|
|
|
@item set exceptions
|
|
@kindex set exceptions@r{, Hurd command}
|
|
Use this command to turn off trapping of exceptions in the inferior.
|
|
When exception trapping is off, neither breakpoints nor
|
|
single-stepping will work. To restore the default, set exception
|
|
trapping on.
|
|
|
|
@item show exceptions
|
|
@kindex show exceptions@r{, Hurd command}
|
|
Show the current state of trapping exceptions in the inferior.
|
|
|
|
@item set task pause
|
|
@kindex set task@r{, Hurd commands}
|
|
@cindex task attributes (@sc{gnu} Hurd)
|
|
@cindex pause current task (@sc{gnu} Hurd)
|
|
This command toggles task suspension when @value{GDBN} has control.
|
|
Setting it to on takes effect immediately, and the task is suspended
|
|
whenever @value{GDBN} gets control. Setting it to off will take
|
|
effect the next time the inferior is continued. If this option is set
|
|
to off, you can use @code{set thread default pause on} or @code{set
|
|
thread pause on} (see below) to pause individual threads.
|
|
|
|
@item show task pause
|
|
@kindex show task@r{, Hurd commands}
|
|
Show the current state of task suspension.
|
|
|
|
@item set task detach-suspend-count
|
|
@cindex task suspend count
|
|
@cindex detach from task, @sc{gnu} Hurd
|
|
This command sets the suspend count the task will be left with when
|
|
@value{GDBN} detaches from it.
|
|
|
|
@item show task detach-suspend-count
|
|
Show the suspend count the task will be left with when detaching.
|
|
|
|
@item set task exception-port
|
|
@itemx set task excp
|
|
@cindex task exception port, @sc{gnu} Hurd
|
|
This command sets the task exception port to which @value{GDBN} will
|
|
forward exceptions. The argument should be the value of the @dfn{send
|
|
rights} of the task. @code{set task excp} is a shorthand alias.
|
|
|
|
@item set noninvasive
|
|
@cindex noninvasive task options
|
|
This command switches @value{GDBN} to a mode that is the least
|
|
invasive as far as interfering with the inferior is concerned. This
|
|
is the same as using @code{set task pause}, @code{set exceptions}, and
|
|
@code{set signals} to values opposite to the defaults.
|
|
|
|
@item info send-rights
|
|
@itemx info receive-rights
|
|
@itemx info port-rights
|
|
@itemx info port-sets
|
|
@itemx info dead-names
|
|
@itemx info ports
|
|
@itemx info psets
|
|
@cindex send rights, @sc{gnu} Hurd
|
|
@cindex receive rights, @sc{gnu} Hurd
|
|
@cindex port rights, @sc{gnu} Hurd
|
|
@cindex port sets, @sc{gnu} Hurd
|
|
@cindex dead names, @sc{gnu} Hurd
|
|
These commands display information about, respectively, send rights,
|
|
receive rights, port rights, port sets, and dead names of a task.
|
|
There are also shorthand aliases: @code{info ports} for @code{info
|
|
port-rights} and @code{info psets} for @code{info port-sets}.
|
|
|
|
@item set thread pause
|
|
@kindex set thread@r{, Hurd command}
|
|
@cindex thread properties, @sc{gnu} Hurd
|
|
@cindex pause current thread (@sc{gnu} Hurd)
|
|
This command toggles current thread suspension when @value{GDBN} has
|
|
control. Setting it to on takes effect immediately, and the current
|
|
thread is suspended whenever @value{GDBN} gets control. Setting it to
|
|
off will take effect the next time the inferior is continued.
|
|
Normally, this command has no effect, since when @value{GDBN} has
|
|
control, the whole task is suspended. However, if you used @code{set
|
|
task pause off} (see above), this command comes in handy to suspend
|
|
only the current thread.
|
|
|
|
@item show thread pause
|
|
@kindex show thread@r{, Hurd command}
|
|
This command shows the state of current thread suspension.
|
|
|
|
@item set thread run
|
|
This command sets whether the current thread is allowed to run.
|
|
|
|
@item show thread run
|
|
Show whether the current thread is allowed to run.
|
|
|
|
@item set thread detach-suspend-count
|
|
@cindex thread suspend count, @sc{gnu} Hurd
|
|
@cindex detach from thread, @sc{gnu} Hurd
|
|
This command sets the suspend count @value{GDBN} will leave on a
|
|
thread when detaching. This number is relative to the suspend count
|
|
found by @value{GDBN} when it notices the thread; use @code{set thread
|
|
takeover-suspend-count} to force it to an absolute value.
|
|
|
|
@item show thread detach-suspend-count
|
|
Show the suspend count @value{GDBN} will leave on the thread when
|
|
detaching.
|
|
|
|
@item set thread exception-port
|
|
@itemx set thread excp
|
|
Set the thread exception port to which to forward exceptions. This
|
|
overrides the port set by @code{set task exception-port} (see above).
|
|
@code{set thread excp} is the shorthand alias.
|
|
|
|
@item set thread takeover-suspend-count
|
|
Normally, @value{GDBN}'s thread suspend counts are relative to the
|
|
value @value{GDBN} finds when it notices each thread. This command
|
|
changes the suspend counts to be absolute instead.
|
|
|
|
@item set thread default
|
|
@itemx show thread default
|
|
@cindex thread default settings, @sc{gnu} Hurd
|
|
Each of the above @code{set thread} commands has a @code{set thread
|
|
default} counterpart (e.g., @code{set thread default pause}, @code{set
|
|
thread default exception-port}, etc.). The @code{thread default}
|
|
variety of commands sets the default thread properties for all
|
|
threads; you can then change the properties of individual threads with
|
|
the non-default commands.
|
|
@end table
|
|
|
|
@node Darwin
|
|
@subsection Darwin
|
|
@cindex Darwin
|
|
|
|
@value{GDBN} provides the following commands specific to the Darwin target:
|
|
|
|
@table @code
|
|
@item set debug darwin @var{num}
|
|
@kindex set debug darwin
|
|
When set to a non zero value, enables debugging messages specific to
|
|
the Darwin support. Higher values produce more verbose output.
|
|
|
|
@item show debug darwin
|
|
@kindex show debug darwin
|
|
Show the current state of Darwin messages.
|
|
|
|
@item set debug mach-o @var{num}
|
|
@kindex set debug mach-o
|
|
When set to a non zero value, enables debugging messages while
|
|
@value{GDBN} is reading Darwin object files. (@dfn{Mach-O} is the
|
|
file format used on Darwin for object and executable files.) Higher
|
|
values produce more verbose output. This is a command to diagnose
|
|
problems internal to @value{GDBN} and should not be needed in normal
|
|
usage.
|
|
|
|
@item show debug mach-o
|
|
@kindex show debug mach-o
|
|
Show the current state of Mach-O file messages.
|
|
|
|
@item set mach-exceptions on
|
|
@itemx set mach-exceptions off
|
|
@kindex set mach-exceptions
|
|
On Darwin, faults are first reported as a Mach exception and are then
|
|
mapped to a Posix signal. Use this command to turn on trapping of
|
|
Mach exceptions in the inferior. This might be sometimes useful to
|
|
better understand the cause of a fault. The default is off.
|
|
|
|
@item show mach-exceptions
|
|
@kindex show mach-exceptions
|
|
Show the current state of exceptions trapping.
|
|
@end table
|
|
|
|
|
|
@node Embedded OS
|
|
@section Embedded Operating Systems
|
|
|
|
This section describes configurations involving the debugging of
|
|
embedded operating systems that are available for several different
|
|
architectures.
|
|
|
|
@menu
|
|
* VxWorks:: Using @value{GDBN} with VxWorks
|
|
@end menu
|
|
|
|
@value{GDBN} includes the ability to debug programs running on
|
|
various real-time operating systems.
|
|
|
|
@node VxWorks
|
|
@subsection Using @value{GDBN} with VxWorks
|
|
|
|
@cindex VxWorks
|
|
|
|
@table @code
|
|
|
|
@kindex target vxworks
|
|
@item target vxworks @var{machinename}
|
|
A VxWorks system, attached via TCP/IP. The argument @var{machinename}
|
|
is the target system's machine name or IP address.
|
|
|
|
@end table
|
|
|
|
On VxWorks, @code{load} links @var{filename} dynamically on the
|
|
current target system as well as adding its symbols in @value{GDBN}.
|
|
|
|
@value{GDBN} enables developers to spawn and debug tasks running on networked
|
|
VxWorks targets from a Unix host. Already-running tasks spawned from
|
|
the VxWorks shell can also be debugged. @value{GDBN} uses code that runs on
|
|
both the Unix host and on the VxWorks target. The program
|
|
@code{@value{GDBP}} is installed and executed on the Unix host. (It may be
|
|
installed with the name @code{vxgdb}, to distinguish it from a
|
|
@value{GDBN} for debugging programs on the host itself.)
|
|
|
|
@table @code
|
|
@item VxWorks-timeout @var{args}
|
|
@kindex vxworks-timeout
|
|
All VxWorks-based targets now support the option @code{vxworks-timeout}.
|
|
This option is set by the user, and @var{args} represents the number of
|
|
seconds @value{GDBN} waits for responses to rpc's. You might use this if
|
|
your VxWorks target is a slow software simulator or is on the far side
|
|
of a thin network line.
|
|
@end table
|
|
|
|
The following information on connecting to VxWorks was current when
|
|
this manual was produced; newer releases of VxWorks may use revised
|
|
procedures.
|
|
|
|
@findex INCLUDE_RDB
|
|
To use @value{GDBN} with VxWorks, you must rebuild your VxWorks kernel
|
|
to include the remote debugging interface routines in the VxWorks
|
|
library @file{rdb.a}. To do this, define @code{INCLUDE_RDB} in the
|
|
VxWorks configuration file @file{configAll.h} and rebuild your VxWorks
|
|
kernel. The resulting kernel contains @file{rdb.a}, and spawns the
|
|
source debugging task @code{tRdbTask} when VxWorks is booted. For more
|
|
information on configuring and remaking VxWorks, see the manufacturer's
|
|
manual.
|
|
@c VxWorks, see the @cite{VxWorks Programmer's Guide}.
|
|
|
|
Once you have included @file{rdb.a} in your VxWorks system image and set
|
|
your Unix execution search path to find @value{GDBN}, you are ready to
|
|
run @value{GDBN}. From your Unix host, run @code{@value{GDBP}} (or
|
|
@code{vxgdb}, depending on your installation).
|
|
|
|
@value{GDBN} comes up showing the prompt:
|
|
|
|
@smallexample
|
|
(vxgdb)
|
|
@end smallexample
|
|
|
|
@menu
|
|
* VxWorks Connection:: Connecting to VxWorks
|
|
* VxWorks Download:: VxWorks download
|
|
* VxWorks Attach:: Running tasks
|
|
@end menu
|
|
|
|
@node VxWorks Connection
|
|
@subsubsection Connecting to VxWorks
|
|
|
|
The @value{GDBN} command @code{target} lets you connect to a VxWorks target on the
|
|
network. To connect to a target whose host name is ``@code{tt}'', type:
|
|
|
|
@smallexample
|
|
(vxgdb) target vxworks tt
|
|
@end smallexample
|
|
|
|
@need 750
|
|
@value{GDBN} displays messages like these:
|
|
|
|
@smallexample
|
|
Attaching remote machine across net...
|
|
Connected to tt.
|
|
@end smallexample
|
|
|
|
@need 1000
|
|
@value{GDBN} then attempts to read the symbol tables of any object modules
|
|
loaded into the VxWorks target since it was last booted. @value{GDBN} locates
|
|
these files by searching the directories listed in the command search
|
|
path (@pxref{Environment, ,Your Program's Environment}); if it fails
|
|
to find an object file, it displays a message such as:
|
|
|
|
@smallexample
|
|
prog.o: No such file or directory.
|
|
@end smallexample
|
|
|
|
When this happens, add the appropriate directory to the search path with
|
|
the @value{GDBN} command @code{path}, and execute the @code{target}
|
|
command again.
|
|
|
|
@node VxWorks Download
|
|
@subsubsection VxWorks Download
|
|
|
|
@cindex download to VxWorks
|
|
If you have connected to the VxWorks target and you want to debug an
|
|
object that has not yet been loaded, you can use the @value{GDBN}
|
|
@code{load} command to download a file from Unix to VxWorks
|
|
incrementally. The object file given as an argument to the @code{load}
|
|
command is actually opened twice: first by the VxWorks target in order
|
|
to download the code, then by @value{GDBN} in order to read the symbol
|
|
table. This can lead to problems if the current working directories on
|
|
the two systems differ. If both systems have NFS mounted the same
|
|
filesystems, you can avoid these problems by using absolute paths.
|
|
Otherwise, it is simplest to set the working directory on both systems
|
|
to the directory in which the object file resides, and then to reference
|
|
the file by its name, without any path. For instance, a program
|
|
@file{prog.o} may reside in @file{@var{vxpath}/vw/demo/rdb} in VxWorks
|
|
and in @file{@var{hostpath}/vw/demo/rdb} on the host. To load this
|
|
program, type this on VxWorks:
|
|
|
|
@smallexample
|
|
-> cd "@var{vxpath}/vw/demo/rdb"
|
|
@end smallexample
|
|
|
|
@noindent
|
|
Then, in @value{GDBN}, type:
|
|
|
|
@smallexample
|
|
(vxgdb) cd @var{hostpath}/vw/demo/rdb
|
|
(vxgdb) load prog.o
|
|
@end smallexample
|
|
|
|
@value{GDBN} displays a response similar to this:
|
|
|
|
@smallexample
|
|
Reading symbol data from wherever/vw/demo/rdb/prog.o... done.
|
|
@end smallexample
|
|
|
|
You can also use the @code{load} command to reload an object module
|
|
after editing and recompiling the corresponding source file. Note that
|
|
this makes @value{GDBN} delete all currently-defined breakpoints,
|
|
auto-displays, and convenience variables, and to clear the value
|
|
history. (This is necessary in order to preserve the integrity of
|
|
debugger's data structures that reference the target system's symbol
|
|
table.)
|
|
|
|
@node VxWorks Attach
|
|
@subsubsection Running Tasks
|
|
|
|
@cindex running VxWorks tasks
|
|
You can also attach to an existing task using the @code{attach} command as
|
|
follows:
|
|
|
|
@smallexample
|
|
(vxgdb) attach @var{task}
|
|
@end smallexample
|
|
|
|
@noindent
|
|
where @var{task} is the VxWorks hexadecimal task ID. The task can be running
|
|
or suspended when you attach to it. Running tasks are suspended at
|
|
the time of attachment.
|
|
|
|
@node Embedded Processors
|
|
@section Embedded Processors
|
|
|
|
This section goes into details specific to particular embedded
|
|
configurations.
|
|
|
|
@cindex send command to simulator
|
|
Whenever a specific embedded processor has a simulator, @value{GDBN}
|
|
allows to send an arbitrary command to the simulator.
|
|
|
|
@table @code
|
|
@item sim @var{command}
|
|
@kindex sim@r{, a command}
|
|
Send an arbitrary @var{command} string to the simulator. Consult the
|
|
documentation for the specific simulator in use for information about
|
|
acceptable commands.
|
|
@end table
|
|
|
|
|
|
@menu
|
|
* ARM:: ARM RDI
|
|
* M32R/D:: Renesas M32R/D
|
|
* M68K:: Motorola M68K
|
|
* MicroBlaze:: Xilinx MicroBlaze
|
|
* MIPS Embedded:: MIPS Embedded
|
|
* OpenRISC 1000:: OpenRisc 1000
|
|
* PowerPC Embedded:: PowerPC Embedded
|
|
* PA:: HP PA Embedded
|
|
* Sparclet:: Tsqware Sparclet
|
|
* Sparclite:: Fujitsu Sparclite
|
|
* Z8000:: Zilog Z8000
|
|
* AVR:: Atmel AVR
|
|
* CRIS:: CRIS
|
|
* Super-H:: Renesas Super-H
|
|
@end menu
|
|
|
|
@node ARM
|
|
@subsection ARM
|
|
@cindex ARM RDI
|
|
|
|
@table @code
|
|
@kindex target rdi
|
|
@item target rdi @var{dev}
|
|
ARM Angel monitor, via RDI library interface to ADP protocol. You may
|
|
use this target to communicate with both boards running the Angel
|
|
monitor, or with the EmbeddedICE JTAG debug device.
|
|
|
|
@kindex target rdp
|
|
@item target rdp @var{dev}
|
|
ARM Demon monitor.
|
|
|
|
@end table
|
|
|
|
@value{GDBN} provides the following ARM-specific commands:
|
|
|
|
@table @code
|
|
@item set arm disassembler
|
|
@kindex set arm
|
|
This commands selects from a list of disassembly styles. The
|
|
@code{"std"} style is the standard style.
|
|
|
|
@item show arm disassembler
|
|
@kindex show arm
|
|
Show the current disassembly style.
|
|
|
|
@item set arm apcs32
|
|
@cindex ARM 32-bit mode
|
|
This command toggles ARM operation mode between 32-bit and 26-bit.
|
|
|
|
@item show arm apcs32
|
|
Display the current usage of the ARM 32-bit mode.
|
|
|
|
@item set arm fpu @var{fputype}
|
|
This command sets the ARM floating-point unit (FPU) type. The
|
|
argument @var{fputype} can be one of these:
|
|
|
|
@table @code
|
|
@item auto
|
|
Determine the FPU type by querying the OS ABI.
|
|
@item softfpa
|
|
Software FPU, with mixed-endian doubles on little-endian ARM
|
|
processors.
|
|
@item fpa
|
|
GCC-compiled FPA co-processor.
|
|
@item softvfp
|
|
Software FPU with pure-endian doubles.
|
|
@item vfp
|
|
VFP co-processor.
|
|
@end table
|
|
|
|
@item show arm fpu
|
|
Show the current type of the FPU.
|
|
|
|
@item set arm abi
|
|
This command forces @value{GDBN} to use the specified ABI.
|
|
|
|
@item show arm abi
|
|
Show the currently used ABI.
|
|
|
|
@item set arm fallback-mode (arm|thumb|auto)
|
|
@value{GDBN} uses the symbol table, when available, to determine
|
|
whether instructions are ARM or Thumb. This command controls
|
|
@value{GDBN}'s default behavior when the symbol table is not
|
|
available. The default is @samp{auto}, which causes @value{GDBN} to
|
|
use the current execution mode (from the @code{T} bit in the @code{CPSR}
|
|
register).
|
|
|
|
@item show arm fallback-mode
|
|
Show the current fallback instruction mode.
|
|
|
|
@item set arm force-mode (arm|thumb|auto)
|
|
This command overrides use of the symbol table to determine whether
|
|
instructions are ARM or Thumb. The default is @samp{auto}, which
|
|
causes @value{GDBN} to use the symbol table and then the setting
|
|
of @samp{set arm fallback-mode}.
|
|
|
|
@item show arm force-mode
|
|
Show the current forced instruction mode.
|
|
|
|
@item set debug arm
|
|
Toggle whether to display ARM-specific debugging messages from the ARM
|
|
target support subsystem.
|
|
|
|
@item show debug arm
|
|
Show whether ARM-specific debugging messages are enabled.
|
|
@end table
|
|
|
|
The following commands are available when an ARM target is debugged
|
|
using the RDI interface:
|
|
|
|
@table @code
|
|
@item rdilogfile @r{[}@var{file}@r{]}
|
|
@kindex rdilogfile
|
|
@cindex ADP (Angel Debugger Protocol) logging
|
|
Set the filename for the ADP (Angel Debugger Protocol) packet log.
|
|
With an argument, sets the log file to the specified @var{file}. With
|
|
no argument, show the current log file name. The default log file is
|
|
@file{rdi.log}.
|
|
|
|
@item rdilogenable @r{[}@var{arg}@r{]}
|
|
@kindex rdilogenable
|
|
Control logging of ADP packets. With an argument of 1 or @code{"yes"}
|
|
enables logging, with an argument 0 or @code{"no"} disables it. With
|
|
no arguments displays the current setting. When logging is enabled,
|
|
ADP packets exchanged between @value{GDBN} and the RDI target device
|
|
are logged to a file.
|
|
|
|
@item set rdiromatzero
|
|
@kindex set rdiromatzero
|
|
@cindex ROM at zero address, RDI
|
|
Tell @value{GDBN} whether the target has ROM at address 0. If on,
|
|
vector catching is disabled, so that zero address can be used. If off
|
|
(the default), vector catching is enabled. For this command to take
|
|
effect, it needs to be invoked prior to the @code{target rdi} command.
|
|
|
|
@item show rdiromatzero
|
|
@kindex show rdiromatzero
|
|
Show the current setting of ROM at zero address.
|
|
|
|
@item set rdiheartbeat
|
|
@kindex set rdiheartbeat
|
|
@cindex RDI heartbeat
|
|
Enable or disable RDI heartbeat packets. It is not recommended to
|
|
turn on this option, since it confuses ARM and EPI JTAG interface, as
|
|
well as the Angel monitor.
|
|
|
|
@item show rdiheartbeat
|
|
@kindex show rdiheartbeat
|
|
Show the setting of RDI heartbeat packets.
|
|
@end table
|
|
|
|
@table @code
|
|
@item target sim @r{[}@var{simargs}@r{]} @dots{}
|
|
The @value{GDBN} ARM simulator accepts the following optional arguments.
|
|
|
|
@table @code
|
|
@item --swi-support=@var{type}
|
|
Tell the simulator which SWI interfaces to support.
|
|
@var{type} may be a comma separated list of the following values.
|
|
The default value is @code{all}.
|
|
|
|
@table @code
|
|
@item none
|
|
@item demon
|
|
@item angel
|
|
@item redboot
|
|
@item all
|
|
@end table
|
|
@end table
|
|
@end table
|
|
|
|
@node M32R/D
|
|
@subsection Renesas M32R/D and M32R/SDI
|
|
|
|
@table @code
|
|
@kindex target m32r
|
|
@item target m32r @var{dev}
|
|
Renesas M32R/D ROM monitor.
|
|
|
|
@kindex target m32rsdi
|
|
@item target m32rsdi @var{dev}
|
|
Renesas M32R SDI server, connected via parallel port to the board.
|
|
@end table
|
|
|
|
The following @value{GDBN} commands are specific to the M32R monitor:
|
|
|
|
@table @code
|
|
@item set download-path @var{path}
|
|
@kindex set download-path
|
|
@cindex find downloadable @sc{srec} files (M32R)
|
|
Set the default path for finding downloadable @sc{srec} files.
|
|
|
|
@item show download-path
|
|
@kindex show download-path
|
|
Show the default path for downloadable @sc{srec} files.
|
|
|
|
@item set board-address @var{addr}
|
|
@kindex set board-address
|
|
@cindex M32-EVA target board address
|
|
Set the IP address for the M32R-EVA target board.
|
|
|
|
@item show board-address
|
|
@kindex show board-address
|
|
Show the current IP address of the target board.
|
|
|
|
@item set server-address @var{addr}
|
|
@kindex set server-address
|
|
@cindex download server address (M32R)
|
|
Set the IP address for the download server, which is the @value{GDBN}'s
|
|
host machine.
|
|
|
|
@item show server-address
|
|
@kindex show server-address
|
|
Display the IP address of the download server.
|
|
|
|
@item upload @r{[}@var{file}@r{]}
|
|
@kindex upload@r{, M32R}
|
|
Upload the specified @sc{srec} @var{file} via the monitor's Ethernet
|
|
upload capability. If no @var{file} argument is given, the current
|
|
executable file is uploaded.
|
|
|
|
@item tload @r{[}@var{file}@r{]}
|
|
@kindex tload@r{, M32R}
|
|
Test the @code{upload} command.
|
|
@end table
|
|
|
|
The following commands are available for M32R/SDI:
|
|
|
|
@table @code
|
|
@item sdireset
|
|
@kindex sdireset
|
|
@cindex reset SDI connection, M32R
|
|
This command resets the SDI connection.
|
|
|
|
@item sdistatus
|
|
@kindex sdistatus
|
|
This command shows the SDI connection status.
|
|
|
|
@item debug_chaos
|
|
@kindex debug_chaos
|
|
@cindex M32R/Chaos debugging
|
|
Instructs the remote that M32R/Chaos debugging is to be used.
|
|
|
|
@item use_debug_dma
|
|
@kindex use_debug_dma
|
|
Instructs the remote to use the DEBUG_DMA method of accessing memory.
|
|
|
|
@item use_mon_code
|
|
@kindex use_mon_code
|
|
Instructs the remote to use the MON_CODE method of accessing memory.
|
|
|
|
@item use_ib_break
|
|
@kindex use_ib_break
|
|
Instructs the remote to set breakpoints by IB break.
|
|
|
|
@item use_dbt_break
|
|
@kindex use_dbt_break
|
|
Instructs the remote to set breakpoints by DBT.
|
|
@end table
|
|
|
|
@node M68K
|
|
@subsection M68k
|
|
|
|
The Motorola m68k configuration includes ColdFire support, and a
|
|
target command for the following ROM monitor.
|
|
|
|
@table @code
|
|
|
|
@kindex target dbug
|
|
@item target dbug @var{dev}
|
|
dBUG ROM monitor for Motorola ColdFire.
|
|
|
|
@end table
|
|
|
|
@node MicroBlaze
|
|
@subsection MicroBlaze
|
|
@cindex Xilinx MicroBlaze
|
|
@cindex XMD, Xilinx Microprocessor Debugger
|
|
|
|
The MicroBlaze is a soft-core processor supported on various Xilinx
|
|
FPGAs, such as Spartan or Virtex series. Boards with these processors
|
|
usually have JTAG ports which connect to a host system running the Xilinx
|
|
Embedded Development Kit (EDK) or Software Development Kit (SDK).
|
|
This host system is used to download the configuration bitstream to
|
|
the target FPGA. The Xilinx Microprocessor Debugger (XMD) program
|
|
communicates with the target board using the JTAG interface and
|
|
presents a @code{gdbserver} interface to the board. By default
|
|
@code{xmd} uses port @code{1234}. (While it is possible to change
|
|
this default port, it requires the use of undocumented @code{xmd}
|
|
commands. Contact Xilinx support if you need to do this.)
|
|
|
|
Use these GDB commands to connect to the MicroBlaze target processor.
|
|
|
|
@table @code
|
|
@item target remote :1234
|
|
Use this command to connect to the target if you are running @value{GDBN}
|
|
on the same system as @code{xmd}.
|
|
|
|
@item target remote @var{xmd-host}:1234
|
|
Use this command to connect to the target if it is connected to @code{xmd}
|
|
running on a different system named @var{xmd-host}.
|
|
|
|
@item load
|
|
Use this command to download a program to the MicroBlaze target.
|
|
|
|
@item set debug microblaze @var{n}
|
|
Enable MicroBlaze-specific debugging messages if non-zero.
|
|
|
|
@item show debug microblaze @var{n}
|
|
Show MicroBlaze-specific debugging level.
|
|
@end table
|
|
|
|
@node MIPS Embedded
|
|
@subsection @acronym{MIPS} Embedded
|
|
|
|
@cindex @acronym{MIPS} boards
|
|
@value{GDBN} can use the @acronym{MIPS} remote debugging protocol to talk to a
|
|
@acronym{MIPS} board attached to a serial line. This is available when
|
|
you configure @value{GDBN} with @samp{--target=mips-elf}.
|
|
|
|
@need 1000
|
|
Use these @value{GDBN} commands to specify the connection to your target board:
|
|
|
|
@table @code
|
|
@item target mips @var{port}
|
|
@kindex target mips @var{port}
|
|
To run a program on the board, start up @code{@value{GDBP}} with the
|
|
name of your program as the argument. To connect to the board, use the
|
|
command @samp{target mips @var{port}}, where @var{port} is the name of
|
|
the serial port connected to the board. If the program has not already
|
|
been downloaded to the board, you may use the @code{load} command to
|
|
download it. You can then use all the usual @value{GDBN} commands.
|
|
|
|
For example, this sequence connects to the target board through a serial
|
|
port, and loads and runs a program called @var{prog} through the
|
|
debugger:
|
|
|
|
@smallexample
|
|
host$ @value{GDBP} @var{prog}
|
|
@value{GDBN} is free software and @dots{}
|
|
(@value{GDBP}) target mips /dev/ttyb
|
|
(@value{GDBP}) load @var{prog}
|
|
(@value{GDBP}) run
|
|
@end smallexample
|
|
|
|
@item target mips @var{hostname}:@var{portnumber}
|
|
On some @value{GDBN} host configurations, you can specify a TCP
|
|
connection (for instance, to a serial line managed by a terminal
|
|
concentrator) instead of a serial port, using the syntax
|
|
@samp{@var{hostname}:@var{portnumber}}.
|
|
|
|
@item target pmon @var{port}
|
|
@kindex target pmon @var{port}
|
|
PMON ROM monitor.
|
|
|
|
@item target ddb @var{port}
|
|
@kindex target ddb @var{port}
|
|
NEC's DDB variant of PMON for Vr4300.
|
|
|
|
@item target lsi @var{port}
|
|
@kindex target lsi @var{port}
|
|
LSI variant of PMON.
|
|
|
|
@kindex target r3900
|
|
@item target r3900 @var{dev}
|
|
Densan DVE-R3900 ROM monitor for Toshiba R3900 Mips.
|
|
|
|
@kindex target array
|
|
@item target array @var{dev}
|
|
Array Tech LSI33K RAID controller board.
|
|
|
|
@end table
|
|
|
|
|
|
@noindent
|
|
@value{GDBN} also supports these special commands for @acronym{MIPS} targets:
|
|
|
|
@table @code
|
|
@item set mipsfpu double
|
|
@itemx set mipsfpu single
|
|
@itemx set mipsfpu none
|
|
@itemx set mipsfpu auto
|
|
@itemx show mipsfpu
|
|
@kindex set mipsfpu
|
|
@kindex show mipsfpu
|
|
@cindex @acronym{MIPS} remote floating point
|
|
@cindex floating point, @acronym{MIPS} remote
|
|
If your target board does not support the @acronym{MIPS} floating point
|
|
coprocessor, you should use the command @samp{set mipsfpu none} (if you
|
|
need this, you may wish to put the command in your @value{GDBN} init
|
|
file). This tells @value{GDBN} how to find the return value of
|
|
functions which return floating point values. It also allows
|
|
@value{GDBN} to avoid saving the floating point registers when calling
|
|
functions on the board. If you are using a floating point coprocessor
|
|
with only single precision floating point support, as on the @sc{r4650}
|
|
processor, use the command @samp{set mipsfpu single}. The default
|
|
double precision floating point coprocessor may be selected using
|
|
@samp{set mipsfpu double}.
|
|
|
|
In previous versions the only choices were double precision or no
|
|
floating point, so @samp{set mipsfpu on} will select double precision
|
|
and @samp{set mipsfpu off} will select no floating point.
|
|
|
|
As usual, you can inquire about the @code{mipsfpu} variable with
|
|
@samp{show mipsfpu}.
|
|
|
|
@item set timeout @var{seconds}
|
|
@itemx set retransmit-timeout @var{seconds}
|
|
@itemx show timeout
|
|
@itemx show retransmit-timeout
|
|
@cindex @code{timeout}, @acronym{MIPS} protocol
|
|
@cindex @code{retransmit-timeout}, @acronym{MIPS} protocol
|
|
@kindex set timeout
|
|
@kindex show timeout
|
|
@kindex set retransmit-timeout
|
|
@kindex show retransmit-timeout
|
|
You can control the timeout used while waiting for a packet, in the @acronym{MIPS}
|
|
remote protocol, with the @code{set timeout @var{seconds}} command. The
|
|
default is 5 seconds. Similarly, you can control the timeout used while
|
|
waiting for an acknowledgment of a packet with the @code{set
|
|
retransmit-timeout @var{seconds}} command. The default is 3 seconds.
|
|
You can inspect both values with @code{show timeout} and @code{show
|
|
retransmit-timeout}. (These commands are @emph{only} available when
|
|
@value{GDBN} is configured for @samp{--target=mips-elf}.)
|
|
|
|
The timeout set by @code{set timeout} does not apply when @value{GDBN}
|
|
is waiting for your program to stop. In that case, @value{GDBN} waits
|
|
forever because it has no way of knowing how long the program is going
|
|
to run before stopping.
|
|
|
|
@item set syn-garbage-limit @var{num}
|
|
@kindex set syn-garbage-limit@r{, @acronym{MIPS} remote}
|
|
@cindex synchronize with remote @acronym{MIPS} target
|
|
Limit the maximum number of characters @value{GDBN} should ignore when
|
|
it tries to synchronize with the remote target. The default is 10
|
|
characters. Setting the limit to -1 means there's no limit.
|
|
|
|
@item show syn-garbage-limit
|
|
@kindex show syn-garbage-limit@r{, @acronym{MIPS} remote}
|
|
Show the current limit on the number of characters to ignore when
|
|
trying to synchronize with the remote system.
|
|
|
|
@item set monitor-prompt @var{prompt}
|
|
@kindex set monitor-prompt@r{, @acronym{MIPS} remote}
|
|
@cindex remote monitor prompt
|
|
Tell @value{GDBN} to expect the specified @var{prompt} string from the
|
|
remote monitor. The default depends on the target:
|
|
@table @asis
|
|
@item pmon target
|
|
@samp{PMON}
|
|
@item ddb target
|
|
@samp{NEC010}
|
|
@item lsi target
|
|
@samp{PMON>}
|
|
@end table
|
|
|
|
@item show monitor-prompt
|
|
@kindex show monitor-prompt@r{, @acronym{MIPS} remote}
|
|
Show the current strings @value{GDBN} expects as the prompt from the
|
|
remote monitor.
|
|
|
|
@item set monitor-warnings
|
|
@kindex set monitor-warnings@r{, @acronym{MIPS} remote}
|
|
Enable or disable monitor warnings about hardware breakpoints. This
|
|
has effect only for the @code{lsi} target. When on, @value{GDBN} will
|
|
display warning messages whose codes are returned by the @code{lsi}
|
|
PMON monitor for breakpoint commands.
|
|
|
|
@item show monitor-warnings
|
|
@kindex show monitor-warnings@r{, @acronym{MIPS} remote}
|
|
Show the current setting of printing monitor warnings.
|
|
|
|
@item pmon @var{command}
|
|
@kindex pmon@r{, @acronym{MIPS} remote}
|
|
@cindex send PMON command
|
|
This command allows sending an arbitrary @var{command} string to the
|
|
monitor. The monitor must be in debug mode for this to work.
|
|
@end table
|
|
|
|
@node OpenRISC 1000
|
|
@subsection OpenRISC 1000
|
|
@cindex OpenRISC 1000
|
|
|
|
@cindex or1k boards
|
|
See OR1k Architecture document (@uref{www.opencores.org}) for more information
|
|
about platform and commands.
|
|
|
|
@table @code
|
|
|
|
@kindex target jtag
|
|
@item target jtag jtag://@var{host}:@var{port}
|
|
|
|
Connects to remote JTAG server.
|
|
JTAG remote server can be either an or1ksim or JTAG server,
|
|
connected via parallel port to the board.
|
|
|
|
Example: @code{target jtag jtag://localhost:9999}
|
|
|
|
@kindex or1ksim
|
|
@item or1ksim @var{command}
|
|
If connected to @code{or1ksim} OpenRISC 1000 Architectural
|
|
Simulator, proprietary commands can be executed.
|
|
|
|
@kindex info or1k spr
|
|
@item info or1k spr
|
|
Displays spr groups.
|
|
|
|
@item info or1k spr @var{group}
|
|
@itemx info or1k spr @var{groupno}
|
|
Displays register names in selected group.
|
|
|
|
@item info or1k spr @var{group} @var{register}
|
|
@itemx info or1k spr @var{register}
|
|
@itemx info or1k spr @var{groupno} @var{registerno}
|
|
@itemx info or1k spr @var{registerno}
|
|
Shows information about specified spr register.
|
|
|
|
@kindex spr
|
|
@item spr @var{group} @var{register} @var{value}
|
|
@itemx spr @var{register @var{value}}
|
|
@itemx spr @var{groupno} @var{registerno @var{value}}
|
|
@itemx spr @var{registerno @var{value}}
|
|
Writes @var{value} to specified spr register.
|
|
@end table
|
|
|
|
Some implementations of OpenRISC 1000 Architecture also have hardware trace.
|
|
It is very similar to @value{GDBN} trace, except it does not interfere with normal
|
|
program execution and is thus much faster. Hardware breakpoints/watchpoint
|
|
triggers can be set using:
|
|
@table @code
|
|
@item $LEA/$LDATA
|
|
Load effective address/data
|
|
@item $SEA/$SDATA
|
|
Store effective address/data
|
|
@item $AEA/$ADATA
|
|
Access effective address ($SEA or $LEA) or data ($SDATA/$LDATA)
|
|
@item $FETCH
|
|
Fetch data
|
|
@end table
|
|
|
|
When triggered, it can capture low level data, like: @code{PC}, @code{LSEA},
|
|
@code{LDATA}, @code{SDATA}, @code{READSPR}, @code{WRITESPR}, @code{INSTR}.
|
|
|
|
@code{htrace} commands:
|
|
@cindex OpenRISC 1000 htrace
|
|
@table @code
|
|
@kindex hwatch
|
|
@item hwatch @var{conditional}
|
|
Set hardware watchpoint on combination of Load/Store Effective Address(es)
|
|
or Data. For example:
|
|
|
|
@code{hwatch ($LEA == my_var) && ($LDATA < 50) || ($SEA == my_var) && ($SDATA >= 50)}
|
|
|
|
@code{hwatch ($LEA == my_var) && ($LDATA < 50) || ($SEA == my_var) && ($SDATA >= 50)}
|
|
|
|
@kindex htrace
|
|
@item htrace info
|
|
Display information about current HW trace configuration.
|
|
|
|
@item htrace trigger @var{conditional}
|
|
Set starting criteria for HW trace.
|
|
|
|
@item htrace qualifier @var{conditional}
|
|
Set acquisition qualifier for HW trace.
|
|
|
|
@item htrace stop @var{conditional}
|
|
Set HW trace stopping criteria.
|
|
|
|
@item htrace record [@var{data}]*
|
|
Selects the data to be recorded, when qualifier is met and HW trace was
|
|
triggered.
|
|
|
|
@item htrace enable
|
|
@itemx htrace disable
|
|
Enables/disables the HW trace.
|
|
|
|
@item htrace rewind [@var{filename}]
|
|
Clears currently recorded trace data.
|
|
|
|
If filename is specified, new trace file is made and any newly collected data
|
|
will be written there.
|
|
|
|
@item htrace print [@var{start} [@var{len}]]
|
|
Prints trace buffer, using current record configuration.
|
|
|
|
@item htrace mode continuous
|
|
Set continuous trace mode.
|
|
|
|
@item htrace mode suspend
|
|
Set suspend trace mode.
|
|
|
|
@end table
|
|
|
|
@node PowerPC Embedded
|
|
@subsection PowerPC Embedded
|
|
|
|
@cindex DVC register
|
|
@value{GDBN} supports using the DVC (Data Value Compare) register to
|
|
implement in hardware simple hardware watchpoint conditions of the form:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) watch @var{ADDRESS|VARIABLE} \
|
|
if @var{ADDRESS|VARIABLE} == @var{CONSTANT EXPRESSION}
|
|
@end smallexample
|
|
|
|
The DVC register will be automatically used when @value{GDBN} detects
|
|
such pattern in a condition expression, and the created watchpoint uses one
|
|
debug register (either the @code{exact-watchpoints} option is on and the
|
|
variable is scalar, or the variable has a length of one byte). This feature
|
|
is available in native @value{GDBN} running on a Linux kernel version 2.6.34
|
|
or newer.
|
|
|
|
When running on PowerPC embedded processors, @value{GDBN} automatically uses
|
|
ranged hardware watchpoints, unless the @code{exact-watchpoints} option is on,
|
|
in which case watchpoints using only one debug register are created when
|
|
watching variables of scalar types.
|
|
|
|
You can create an artificial array to watch an arbitrary memory
|
|
region using one of the following commands (@pxref{Expressions}):
|
|
|
|
@smallexample
|
|
(@value{GDBP}) watch *((char *) @var{address})@@@var{length}
|
|
(@value{GDBP}) watch @{char[@var{length}]@} @var{address}
|
|
@end smallexample
|
|
|
|
PowerPC embedded processors support masked watchpoints. See the discussion
|
|
about the @code{mask} argument in @ref{Set Watchpoints}.
|
|
|
|
@cindex ranged breakpoint
|
|
PowerPC embedded processors support hardware accelerated
|
|
@dfn{ranged breakpoints}. A ranged breakpoint stops execution of
|
|
the inferior whenever it executes an instruction at any address within
|
|
the range it specifies. To set a ranged breakpoint in @value{GDBN},
|
|
use the @code{break-range} command.
|
|
|
|
@value{GDBN} provides the following PowerPC-specific commands:
|
|
|
|
@table @code
|
|
@kindex break-range
|
|
@item break-range @var{start-location}, @var{end-location}
|
|
Set a breakpoint for an address range.
|
|
@var{start-location} and @var{end-location} can specify a function name,
|
|
a line number, an offset of lines from the current line or from the start
|
|
location, or an address of an instruction (see @ref{Specify Location},
|
|
for a list of all the possible ways to specify a @var{location}.)
|
|
The breakpoint will stop execution of the inferior whenever it
|
|
executes an instruction at any address within the specified range,
|
|
(including @var{start-location} and @var{end-location}.)
|
|
|
|
@kindex set powerpc
|
|
@item set powerpc soft-float
|
|
@itemx show powerpc soft-float
|
|
Force @value{GDBN} to use (or not use) a software floating point calling
|
|
convention. By default, @value{GDBN} selects the calling convention based
|
|
on the selected architecture and the provided executable file.
|
|
|
|
@item set powerpc vector-abi
|
|
@itemx show powerpc vector-abi
|
|
Force @value{GDBN} to use the specified calling convention for vector
|
|
arguments and return values. The valid options are @samp{auto};
|
|
@samp{generic}, to avoid vector registers even if they are present;
|
|
@samp{altivec}, to use AltiVec registers; and @samp{spe} to use SPE
|
|
registers. By default, @value{GDBN} selects the calling convention
|
|
based on the selected architecture and the provided executable file.
|
|
|
|
@item set powerpc exact-watchpoints
|
|
@itemx show powerpc exact-watchpoints
|
|
Allow @value{GDBN} to use only one debug register when watching a variable
|
|
of scalar type, thus assuming that the variable is accessed through the
|
|
address of its first byte.
|
|
|
|
@kindex target dink32
|
|
@item target dink32 @var{dev}
|
|
DINK32 ROM monitor.
|
|
|
|
@kindex target ppcbug
|
|
@item target ppcbug @var{dev}
|
|
@kindex target ppcbug1
|
|
@item target ppcbug1 @var{dev}
|
|
PPCBUG ROM monitor for PowerPC.
|
|
|
|
@kindex target sds
|
|
@item target sds @var{dev}
|
|
SDS monitor, running on a PowerPC board (such as Motorola's ADS).
|
|
@end table
|
|
|
|
@cindex SDS protocol
|
|
The following commands specific to the SDS protocol are supported
|
|
by @value{GDBN}:
|
|
|
|
@table @code
|
|
@item set sdstimeout @var{nsec}
|
|
@kindex set sdstimeout
|
|
Set the timeout for SDS protocol reads to be @var{nsec} seconds. The
|
|
default is 2 seconds.
|
|
|
|
@item show sdstimeout
|
|
@kindex show sdstimeout
|
|
Show the current value of the SDS timeout.
|
|
|
|
@item sds @var{command}
|
|
@kindex sds@r{, a command}
|
|
Send the specified @var{command} string to the SDS monitor.
|
|
@end table
|
|
|
|
|
|
@node PA
|
|
@subsection HP PA Embedded
|
|
|
|
@table @code
|
|
|
|
@kindex target op50n
|
|
@item target op50n @var{dev}
|
|
OP50N monitor, running on an OKI HPPA board.
|
|
|
|
@kindex target w89k
|
|
@item target w89k @var{dev}
|
|
W89K monitor, running on a Winbond HPPA board.
|
|
|
|
@end table
|
|
|
|
@node Sparclet
|
|
@subsection Tsqware Sparclet
|
|
|
|
@cindex Sparclet
|
|
|
|
@value{GDBN} enables developers to debug tasks running on
|
|
Sparclet targets from a Unix host.
|
|
@value{GDBN} uses code that runs on
|
|
both the Unix host and on the Sparclet target. The program
|
|
@code{@value{GDBP}} is installed and executed on the Unix host.
|
|
|
|
@table @code
|
|
@item remotetimeout @var{args}
|
|
@kindex remotetimeout
|
|
@value{GDBN} supports the option @code{remotetimeout}.
|
|
This option is set by the user, and @var{args} represents the number of
|
|
seconds @value{GDBN} waits for responses.
|
|
@end table
|
|
|
|
@cindex compiling, on Sparclet
|
|
When compiling for debugging, include the options @samp{-g} to get debug
|
|
information and @samp{-Ttext} to relocate the program to where you wish to
|
|
load it on the target. You may also want to add the options @samp{-n} or
|
|
@samp{-N} in order to reduce the size of the sections. Example:
|
|
|
|
@smallexample
|
|
sparclet-aout-gcc prog.c -Ttext 0x12010000 -g -o prog -N
|
|
@end smallexample
|
|
|
|
You can use @code{objdump} to verify that the addresses are what you intended:
|
|
|
|
@smallexample
|
|
sparclet-aout-objdump --headers --syms prog
|
|
@end smallexample
|
|
|
|
@cindex running, on Sparclet
|
|
Once you have set
|
|
your Unix execution search path to find @value{GDBN}, you are ready to
|
|
run @value{GDBN}. From your Unix host, run @code{@value{GDBP}}
|
|
(or @code{sparclet-aout-gdb}, depending on your installation).
|
|
|
|
@value{GDBN} comes up showing the prompt:
|
|
|
|
@smallexample
|
|
(gdbslet)
|
|
@end smallexample
|
|
|
|
@menu
|
|
* Sparclet File:: Setting the file to debug
|
|
* Sparclet Connection:: Connecting to Sparclet
|
|
* Sparclet Download:: Sparclet download
|
|
* Sparclet Execution:: Running and debugging
|
|
@end menu
|
|
|
|
@node Sparclet File
|
|
@subsubsection Setting File to Debug
|
|
|
|
The @value{GDBN} command @code{file} lets you choose with program to debug.
|
|
|
|
@smallexample
|
|
(gdbslet) file prog
|
|
@end smallexample
|
|
|
|
@need 1000
|
|
@value{GDBN} then attempts to read the symbol table of @file{prog}.
|
|
@value{GDBN} locates
|
|
the file by searching the directories listed in the command search
|
|
path.
|
|
If the file was compiled with debug information (option @samp{-g}), source
|
|
files will be searched as well.
|
|
@value{GDBN} locates
|
|
the source files by searching the directories listed in the directory search
|
|
path (@pxref{Environment, ,Your Program's Environment}).
|
|
If it fails
|
|
to find a file, it displays a message such as:
|
|
|
|
@smallexample
|
|
prog: No such file or directory.
|
|
@end smallexample
|
|
|
|
When this happens, add the appropriate directories to the search paths with
|
|
the @value{GDBN} commands @code{path} and @code{dir}, and execute the
|
|
@code{target} command again.
|
|
|
|
@node Sparclet Connection
|
|
@subsubsection Connecting to Sparclet
|
|
|
|
The @value{GDBN} command @code{target} lets you connect to a Sparclet target.
|
|
To connect to a target on serial port ``@code{ttya}'', type:
|
|
|
|
@smallexample
|
|
(gdbslet) target sparclet /dev/ttya
|
|
Remote target sparclet connected to /dev/ttya
|
|
main () at ../prog.c:3
|
|
@end smallexample
|
|
|
|
@need 750
|
|
@value{GDBN} displays messages like these:
|
|
|
|
@smallexample
|
|
Connected to ttya.
|
|
@end smallexample
|
|
|
|
@node Sparclet Download
|
|
@subsubsection Sparclet Download
|
|
|
|
@cindex download to Sparclet
|
|
Once connected to the Sparclet target,
|
|
you can use the @value{GDBN}
|
|
@code{load} command to download the file from the host to the target.
|
|
The file name and load offset should be given as arguments to the @code{load}
|
|
command.
|
|
Since the file format is aout, the program must be loaded to the starting
|
|
address. You can use @code{objdump} to find out what this value is. The load
|
|
offset is an offset which is added to the VMA (virtual memory address)
|
|
of each of the file's sections.
|
|
For instance, if the program
|
|
@file{prog} was linked to text address 0x1201000, with data at 0x12010160
|
|
and bss at 0x12010170, in @value{GDBN}, type:
|
|
|
|
@smallexample
|
|
(gdbslet) load prog 0x12010000
|
|
Loading section .text, size 0xdb0 vma 0x12010000
|
|
@end smallexample
|
|
|
|
If the code is loaded at a different address then what the program was linked
|
|
to, you may need to use the @code{section} and @code{add-symbol-file} commands
|
|
to tell @value{GDBN} where to map the symbol table.
|
|
|
|
@node Sparclet Execution
|
|
@subsubsection Running and Debugging
|
|
|
|
@cindex running and debugging Sparclet programs
|
|
You can now begin debugging the task using @value{GDBN}'s execution control
|
|
commands, @code{b}, @code{step}, @code{run}, etc. See the @value{GDBN}
|
|
manual for the list of commands.
|
|
|
|
@smallexample
|
|
(gdbslet) b main
|
|
Breakpoint 1 at 0x12010000: file prog.c, line 3.
|
|
(gdbslet) run
|
|
Starting program: prog
|
|
Breakpoint 1, main (argc=1, argv=0xeffff21c) at prog.c:3
|
|
3 char *symarg = 0;
|
|
(gdbslet) step
|
|
4 char *execarg = "hello!";
|
|
(gdbslet)
|
|
@end smallexample
|
|
|
|
@node Sparclite
|
|
@subsection Fujitsu Sparclite
|
|
|
|
@table @code
|
|
|
|
@kindex target sparclite
|
|
@item target sparclite @var{dev}
|
|
Fujitsu sparclite boards, used only for the purpose of loading.
|
|
You must use an additional command to debug the program.
|
|
For example: target remote @var{dev} using @value{GDBN} standard
|
|
remote protocol.
|
|
|
|
@end table
|
|
|
|
@node Z8000
|
|
@subsection Zilog Z8000
|
|
|
|
@cindex Z8000
|
|
@cindex simulator, Z8000
|
|
@cindex Zilog Z8000 simulator
|
|
|
|
When configured for debugging Zilog Z8000 targets, @value{GDBN} includes
|
|
a Z8000 simulator.
|
|
|
|
For the Z8000 family, @samp{target sim} simulates either the Z8002 (the
|
|
unsegmented variant of the Z8000 architecture) or the Z8001 (the
|
|
segmented variant). The simulator recognizes which architecture is
|
|
appropriate by inspecting the object code.
|
|
|
|
@table @code
|
|
@item target sim @var{args}
|
|
@kindex sim
|
|
@kindex target sim@r{, with Z8000}
|
|
Debug programs on a simulated CPU. If the simulator supports setup
|
|
options, specify them via @var{args}.
|
|
@end table
|
|
|
|
@noindent
|
|
After specifying this target, you can debug programs for the simulated
|
|
CPU in the same style as programs for your host computer; use the
|
|
@code{file} command to load a new program image, the @code{run} command
|
|
to run your program, and so on.
|
|
|
|
As well as making available all the usual machine registers
|
|
(@pxref{Registers, ,Registers}), the Z8000 simulator provides three
|
|
additional items of information as specially named registers:
|
|
|
|
@table @code
|
|
|
|
@item cycles
|
|
Counts clock-ticks in the simulator.
|
|
|
|
@item insts
|
|
Counts instructions run in the simulator.
|
|
|
|
@item time
|
|
Execution time in 60ths of a second.
|
|
|
|
@end table
|
|
|
|
You can refer to these values in @value{GDBN} expressions with the usual
|
|
conventions; for example, @w{@samp{b fputc if $cycles>5000}} sets a
|
|
conditional breakpoint that suspends only after at least 5000
|
|
simulated clock ticks.
|
|
|
|
@node AVR
|
|
@subsection Atmel AVR
|
|
@cindex AVR
|
|
|
|
When configured for debugging the Atmel AVR, @value{GDBN} supports the
|
|
following AVR-specific commands:
|
|
|
|
@table @code
|
|
@item info io_registers
|
|
@kindex info io_registers@r{, AVR}
|
|
@cindex I/O registers (Atmel AVR)
|
|
This command displays information about the AVR I/O registers. For
|
|
each register, @value{GDBN} prints its number and value.
|
|
@end table
|
|
|
|
@node CRIS
|
|
@subsection CRIS
|
|
@cindex CRIS
|
|
|
|
When configured for debugging CRIS, @value{GDBN} provides the
|
|
following CRIS-specific commands:
|
|
|
|
@table @code
|
|
@item set cris-version @var{ver}
|
|
@cindex CRIS version
|
|
Set the current CRIS version to @var{ver}, either @samp{10} or @samp{32}.
|
|
The CRIS version affects register names and sizes. This command is useful in
|
|
case autodetection of the CRIS version fails.
|
|
|
|
@item show cris-version
|
|
Show the current CRIS version.
|
|
|
|
@item set cris-dwarf2-cfi
|
|
@cindex DWARF-2 CFI and CRIS
|
|
Set the usage of DWARF-2 CFI for CRIS debugging. The default is @samp{on}.
|
|
Change to @samp{off} when using @code{gcc-cris} whose version is below
|
|
@code{R59}.
|
|
|
|
@item show cris-dwarf2-cfi
|
|
Show the current state of using DWARF-2 CFI.
|
|
|
|
@item set cris-mode @var{mode}
|
|
@cindex CRIS mode
|
|
Set the current CRIS mode to @var{mode}. It should only be changed when
|
|
debugging in guru mode, in which case it should be set to
|
|
@samp{guru} (the default is @samp{normal}).
|
|
|
|
@item show cris-mode
|
|
Show the current CRIS mode.
|
|
@end table
|
|
|
|
@node Super-H
|
|
@subsection Renesas Super-H
|
|
@cindex Super-H
|
|
|
|
For the Renesas Super-H processor, @value{GDBN} provides these
|
|
commands:
|
|
|
|
@table @code
|
|
@item regs
|
|
@kindex regs@r{, Super-H}
|
|
This command is deprecated, and @code{info all-registers} should be
|
|
used instead.
|
|
|
|
Show the values of all Super-H registers.
|
|
|
|
@item set sh calling-convention @var{convention}
|
|
@kindex set sh calling-convention
|
|
Set the calling-convention used when calling functions from @value{GDBN}.
|
|
Allowed values are @samp{gcc}, which is the default setting, and @samp{renesas}.
|
|
With the @samp{gcc} setting, functions are called using the @value{NGCC} calling
|
|
convention. If the DWARF-2 information of the called function specifies
|
|
that the function follows the Renesas calling convention, the function
|
|
is called using the Renesas calling convention. If the calling convention
|
|
is set to @samp{renesas}, the Renesas calling convention is always used,
|
|
regardless of the DWARF-2 information. This can be used to override the
|
|
default of @samp{gcc} if debug information is missing, or the compiler
|
|
does not emit the DWARF-2 calling convention entry for a function.
|
|
|
|
@item show sh calling-convention
|
|
@kindex show sh calling-convention
|
|
Show the current calling convention setting.
|
|
|
|
@end table
|
|
|
|
|
|
@node Architectures
|
|
@section Architectures
|
|
|
|
This section describes characteristics of architectures that affect
|
|
all uses of @value{GDBN} with the architecture, both native and cross.
|
|
|
|
@menu
|
|
* i386::
|
|
* Alpha::
|
|
* MIPS::
|
|
* HPPA:: HP PA architecture
|
|
* SPU:: Cell Broadband Engine SPU architecture
|
|
* PowerPC::
|
|
@end menu
|
|
|
|
@node i386
|
|
@subsection x86 Architecture-specific Issues
|
|
|
|
@table @code
|
|
@item set struct-convention @var{mode}
|
|
@kindex set struct-convention
|
|
@cindex struct return convention
|
|
@cindex struct/union returned in registers
|
|
Set the convention used by the inferior to return @code{struct}s and
|
|
@code{union}s from functions to @var{mode}. Possible values of
|
|
@var{mode} are @code{"pcc"}, @code{"reg"}, and @code{"default"} (the
|
|
default). @code{"default"} or @code{"pcc"} means that @code{struct}s
|
|
are returned on the stack, while @code{"reg"} means that a
|
|
@code{struct} or a @code{union} whose size is 1, 2, 4, or 8 bytes will
|
|
be returned in a register.
|
|
|
|
@item show struct-convention
|
|
@kindex show struct-convention
|
|
Show the current setting of the convention to return @code{struct}s
|
|
from functions.
|
|
@end table
|
|
|
|
@node Alpha
|
|
@subsection Alpha
|
|
|
|
See the following section.
|
|
|
|
@node MIPS
|
|
@subsection @acronym{MIPS}
|
|
|
|
@cindex stack on Alpha
|
|
@cindex stack on @acronym{MIPS}
|
|
@cindex Alpha stack
|
|
@cindex @acronym{MIPS} stack
|
|
Alpha- and @acronym{MIPS}-based computers use an unusual stack frame, which
|
|
sometimes requires @value{GDBN} to search backward in the object code to
|
|
find the beginning of a function.
|
|
|
|
@cindex response time, @acronym{MIPS} debugging
|
|
To improve response time (especially for embedded applications, where
|
|
@value{GDBN} may be restricted to a slow serial line for this search)
|
|
you may want to limit the size of this search, using one of these
|
|
commands:
|
|
|
|
@table @code
|
|
@cindex @code{heuristic-fence-post} (Alpha, @acronym{MIPS})
|
|
@item set heuristic-fence-post @var{limit}
|
|
Restrict @value{GDBN} to examining at most @var{limit} bytes in its
|
|
search for the beginning of a function. A value of @var{0} (the
|
|
default) means there is no limit. However, except for @var{0}, the
|
|
larger the limit the more bytes @code{heuristic-fence-post} must search
|
|
and therefore the longer it takes to run. You should only need to use
|
|
this command when debugging a stripped executable.
|
|
|
|
@item show heuristic-fence-post
|
|
Display the current limit.
|
|
@end table
|
|
|
|
@noindent
|
|
These commands are available @emph{only} when @value{GDBN} is configured
|
|
for debugging programs on Alpha or @acronym{MIPS} processors.
|
|
|
|
Several @acronym{MIPS}-specific commands are available when debugging @acronym{MIPS}
|
|
programs:
|
|
|
|
@table @code
|
|
@item set mips abi @var{arg}
|
|
@kindex set mips abi
|
|
@cindex set ABI for @acronym{MIPS}
|
|
Tell @value{GDBN} which @acronym{MIPS} ABI is used by the inferior. Possible
|
|
values of @var{arg} are:
|
|
|
|
@table @samp
|
|
@item auto
|
|
The default ABI associated with the current binary (this is the
|
|
default).
|
|
@item o32
|
|
@item o64
|
|
@item n32
|
|
@item n64
|
|
@item eabi32
|
|
@item eabi64
|
|
@end table
|
|
|
|
@item show mips abi
|
|
@kindex show mips abi
|
|
Show the @acronym{MIPS} ABI used by @value{GDBN} to debug the inferior.
|
|
|
|
@item set mips compression @var{arg}
|
|
@kindex set mips compression
|
|
@cindex code compression, @acronym{MIPS}
|
|
Tell @value{GDBN} which @acronym{MIPS} compressed
|
|
@acronym{ISA, Instruction Set Architecture} encoding is used by the
|
|
inferior. @value{GDBN} uses this for code disassembly and other
|
|
internal interpretation purposes. This setting is only referred to
|
|
when no executable has been associated with the debugging session or
|
|
the executable does not provide information about the encoding it uses.
|
|
Otherwise this setting is automatically updated from information
|
|
provided by the executable.
|
|
|
|
Possible values of @var{arg} are @samp{mips16} and @samp{micromips}.
|
|
The default compressed @acronym{ISA} encoding is @samp{mips16}, as
|
|
executables containing @acronym{MIPS16} code frequently are not
|
|
identified as such.
|
|
|
|
This setting is ``sticky''; that is, it retains its value across
|
|
debugging sessions until reset either explicitly with this command or
|
|
implicitly from an executable.
|
|
|
|
The compiler and/or assembler typically add symbol table annotations to
|
|
identify functions compiled for the @acronym{MIPS16} or
|
|
@acronym{microMIPS} @acronym{ISA}s. If these function-scope annotations
|
|
are present, @value{GDBN} uses them in preference to the global
|
|
compressed @acronym{ISA} encoding setting.
|
|
|
|
@item show mips compression
|
|
@kindex show mips compression
|
|
Show the @acronym{MIPS} compressed @acronym{ISA} encoding used by
|
|
@value{GDBN} to debug the inferior.
|
|
|
|
@item set mipsfpu
|
|
@itemx show mipsfpu
|
|
@xref{MIPS Embedded, set mipsfpu}.
|
|
|
|
@item set mips mask-address @var{arg}
|
|
@kindex set mips mask-address
|
|
@cindex @acronym{MIPS} addresses, masking
|
|
This command determines whether the most-significant 32 bits of 64-bit
|
|
@acronym{MIPS} addresses are masked off. The argument @var{arg} can be
|
|
@samp{on}, @samp{off}, or @samp{auto}. The latter is the default
|
|
setting, which lets @value{GDBN} determine the correct value.
|
|
|
|
@item show mips mask-address
|
|
@kindex show mips mask-address
|
|
Show whether the upper 32 bits of @acronym{MIPS} addresses are masked off or
|
|
not.
|
|
|
|
@item set remote-mips64-transfers-32bit-regs
|
|
@kindex set remote-mips64-transfers-32bit-regs
|
|
This command controls compatibility with 64-bit @acronym{MIPS} targets that
|
|
transfer data in 32-bit quantities. If you have an old @acronym{MIPS} 64 target
|
|
that transfers 32 bits for some registers, like @sc{sr} and @sc{fsr},
|
|
and 64 bits for other registers, set this option to @samp{on}.
|
|
|
|
@item show remote-mips64-transfers-32bit-regs
|
|
@kindex show remote-mips64-transfers-32bit-regs
|
|
Show the current setting of compatibility with older @acronym{MIPS} 64 targets.
|
|
|
|
@item set debug mips
|
|
@kindex set debug mips
|
|
This command turns on and off debugging messages for the @acronym{MIPS}-specific
|
|
target code in @value{GDBN}.
|
|
|
|
@item show debug mips
|
|
@kindex show debug mips
|
|
Show the current setting of @acronym{MIPS} debugging messages.
|
|
@end table
|
|
|
|
|
|
@node HPPA
|
|
@subsection HPPA
|
|
@cindex HPPA support
|
|
|
|
When @value{GDBN} is debugging the HP PA architecture, it provides the
|
|
following special commands:
|
|
|
|
@table @code
|
|
@item set debug hppa
|
|
@kindex set debug hppa
|
|
This command determines whether HPPA architecture-specific debugging
|
|
messages are to be displayed.
|
|
|
|
@item show debug hppa
|
|
Show whether HPPA debugging messages are displayed.
|
|
|
|
@item maint print unwind @var{address}
|
|
@kindex maint print unwind@r{, HPPA}
|
|
This command displays the contents of the unwind table entry at the
|
|
given @var{address}.
|
|
|
|
@end table
|
|
|
|
|
|
@node SPU
|
|
@subsection Cell Broadband Engine SPU architecture
|
|
@cindex Cell Broadband Engine
|
|
@cindex SPU
|
|
|
|
When @value{GDBN} is debugging the Cell Broadband Engine SPU architecture,
|
|
it provides the following special commands:
|
|
|
|
@table @code
|
|
@item info spu event
|
|
@kindex info spu
|
|
Display SPU event facility status. Shows current event mask
|
|
and pending event status.
|
|
|
|
@item info spu signal
|
|
Display SPU signal notification facility status. Shows pending
|
|
signal-control word and signal notification mode of both signal
|
|
notification channels.
|
|
|
|
@item info spu mailbox
|
|
Display SPU mailbox facility status. Shows all pending entries,
|
|
in order of processing, in each of the SPU Write Outbound,
|
|
SPU Write Outbound Interrupt, and SPU Read Inbound mailboxes.
|
|
|
|
@item info spu dma
|
|
Display MFC DMA status. Shows all pending commands in the MFC
|
|
DMA queue. For each entry, opcode, tag, class IDs, effective
|
|
and local store addresses and transfer size are shown.
|
|
|
|
@item info spu proxydma
|
|
Display MFC Proxy-DMA status. Shows all pending commands in the MFC
|
|
Proxy-DMA queue. For each entry, opcode, tag, class IDs, effective
|
|
and local store addresses and transfer size are shown.
|
|
|
|
@end table
|
|
|
|
When @value{GDBN} is debugging a combined PowerPC/SPU application
|
|
on the Cell Broadband Engine, it provides in addition the following
|
|
special commands:
|
|
|
|
@table @code
|
|
@item set spu stop-on-load @var{arg}
|
|
@kindex set spu
|
|
Set whether to stop for new SPE threads. When set to @code{on}, @value{GDBN}
|
|
will give control to the user when a new SPE thread enters its @code{main}
|
|
function. The default is @code{off}.
|
|
|
|
@item show spu stop-on-load
|
|
@kindex show spu
|
|
Show whether to stop for new SPE threads.
|
|
|
|
@item set spu auto-flush-cache @var{arg}
|
|
Set whether to automatically flush the software-managed cache. When set to
|
|
@code{on}, @value{GDBN} will automatically cause the SPE software-managed
|
|
cache to be flushed whenever SPE execution stops. This provides a consistent
|
|
view of PowerPC memory that is accessed via the cache. If an application
|
|
does not use the software-managed cache, this option has no effect.
|
|
|
|
@item show spu auto-flush-cache
|
|
Show whether to automatically flush the software-managed cache.
|
|
|
|
@end table
|
|
|
|
@node PowerPC
|
|
@subsection PowerPC
|
|
@cindex PowerPC architecture
|
|
|
|
When @value{GDBN} is debugging the PowerPC architecture, it provides a set of
|
|
pseudo-registers to enable inspection of 128-bit wide Decimal Floating Point
|
|
numbers stored in the floating point registers. These values must be stored
|
|
in two consecutive registers, always starting at an even register like
|
|
@code{f0} or @code{f2}.
|
|
|
|
The pseudo-registers go from @code{$dl0} through @code{$dl15}, and are formed
|
|
by joining the even/odd register pairs @code{f0} and @code{f1} for @code{$dl0},
|
|
@code{f2} and @code{f3} for @code{$dl1} and so on.
|
|
|
|
For POWER7 processors, @value{GDBN} provides a set of pseudo-registers, the 64-bit
|
|
wide Extended Floating Point Registers (@samp{f32} through @samp{f63}).
|
|
|
|
|
|
@node Controlling GDB
|
|
@chapter Controlling @value{GDBN}
|
|
|
|
You can alter the way @value{GDBN} interacts with you by using the
|
|
@code{set} command. For commands controlling how @value{GDBN} displays
|
|
data, see @ref{Print Settings, ,Print Settings}. Other settings are
|
|
described here.
|
|
|
|
@menu
|
|
* Prompt:: Prompt
|
|
* Editing:: Command editing
|
|
* Command History:: Command history
|
|
* Screen Size:: Screen size
|
|
* Numbers:: Numbers
|
|
* ABI:: Configuring the current ABI
|
|
* Auto-loading:: Automatically loading associated files
|
|
* Messages/Warnings:: Optional warnings and messages
|
|
* Debugging Output:: Optional messages about internal happenings
|
|
* Other Misc Settings:: Other Miscellaneous Settings
|
|
@end menu
|
|
|
|
@node Prompt
|
|
@section Prompt
|
|
|
|
@cindex prompt
|
|
|
|
@value{GDBN} indicates its readiness to read a command by printing a string
|
|
called the @dfn{prompt}. This string is normally @samp{(@value{GDBP})}. You
|
|
can change the prompt string with the @code{set prompt} command. For
|
|
instance, when debugging @value{GDBN} with @value{GDBN}, it is useful to change
|
|
the prompt in one of the @value{GDBN} sessions so that you can always tell
|
|
which one you are talking to.
|
|
|
|
@emph{Note:} @code{set prompt} does not add a space for you after the
|
|
prompt you set. This allows you to set a prompt which ends in a space
|
|
or a prompt that does not.
|
|
|
|
@table @code
|
|
@kindex set prompt
|
|
@item set prompt @var{newprompt}
|
|
Directs @value{GDBN} to use @var{newprompt} as its prompt string henceforth.
|
|
|
|
@kindex show prompt
|
|
@item show prompt
|
|
Prints a line of the form: @samp{Gdb's prompt is: @var{your-prompt}}
|
|
@end table
|
|
|
|
Versions of @value{GDBN} that ship with Python scripting enabled have
|
|
prompt extensions. The commands for interacting with these extensions
|
|
are:
|
|
|
|
@table @code
|
|
@kindex set extended-prompt
|
|
@item set extended-prompt @var{prompt}
|
|
Set an extended prompt that allows for substitutions.
|
|
@xref{gdb.prompt}, for a list of escape sequences that can be used for
|
|
substitution. Any escape sequences specified as part of the prompt
|
|
string are replaced with the corresponding strings each time the prompt
|
|
is displayed.
|
|
|
|
For example:
|
|
|
|
@smallexample
|
|
set extended-prompt Current working directory: \w (gdb)
|
|
@end smallexample
|
|
|
|
Note that when an extended-prompt is set, it takes control of the
|
|
@var{prompt_hook} hook. @xref{prompt_hook}, for further information.
|
|
|
|
@kindex show extended-prompt
|
|
@item show extended-prompt
|
|
Prints the extended prompt. Any escape sequences specified as part of
|
|
the prompt string with @code{set extended-prompt}, are replaced with the
|
|
corresponding strings each time the prompt is displayed.
|
|
@end table
|
|
|
|
@node Editing
|
|
@section Command Editing
|
|
@cindex readline
|
|
@cindex command line editing
|
|
|
|
@value{GDBN} reads its input commands via the @dfn{Readline} interface. This
|
|
@sc{gnu} library provides consistent behavior for programs which provide a
|
|
command line interface to the user. Advantages are @sc{gnu} Emacs-style
|
|
or @dfn{vi}-style inline editing of commands, @code{csh}-like history
|
|
substitution, and a storage and recall of command history across
|
|
debugging sessions.
|
|
|
|
You may control the behavior of command line editing in @value{GDBN} with the
|
|
command @code{set}.
|
|
|
|
@table @code
|
|
@kindex set editing
|
|
@cindex editing
|
|
@item set editing
|
|
@itemx set editing on
|
|
Enable command line editing (enabled by default).
|
|
|
|
@item set editing off
|
|
Disable command line editing.
|
|
|
|
@kindex show editing
|
|
@item show editing
|
|
Show whether command line editing is enabled.
|
|
@end table
|
|
|
|
@ifset SYSTEM_READLINE
|
|
@xref{Command Line Editing, , , rluserman, GNU Readline Library},
|
|
@end ifset
|
|
@ifclear SYSTEM_READLINE
|
|
@xref{Command Line Editing},
|
|
@end ifclear
|
|
for more details about the Readline
|
|
interface. Users unfamiliar with @sc{gnu} Emacs or @code{vi} are
|
|
encouraged to read that chapter.
|
|
|
|
@node Command History
|
|
@section Command History
|
|
@cindex command history
|
|
|
|
@value{GDBN} can keep track of the commands you type during your
|
|
debugging sessions, so that you can be certain of precisely what
|
|
happened. Use these commands to manage the @value{GDBN} command
|
|
history facility.
|
|
|
|
@value{GDBN} uses the @sc{gnu} History library, a part of the Readline
|
|
package, to provide the history facility.
|
|
@ifset SYSTEM_READLINE
|
|
@xref{Using History Interactively, , , history, GNU History Library},
|
|
@end ifset
|
|
@ifclear SYSTEM_READLINE
|
|
@xref{Using History Interactively},
|
|
@end ifclear
|
|
for the detailed description of the History library.
|
|
|
|
To issue a command to @value{GDBN} without affecting certain aspects of
|
|
the state which is seen by users, prefix it with @samp{server }
|
|
(@pxref{Server Prefix}). This
|
|
means that this command will not affect the command history, nor will it
|
|
affect @value{GDBN}'s notion of which command to repeat if @key{RET} is
|
|
pressed on a line by itself.
|
|
|
|
@cindex @code{server}, command prefix
|
|
The server prefix does not affect the recording of values into the value
|
|
history; to print a value without recording it into the value history,
|
|
use the @code{output} command instead of the @code{print} command.
|
|
|
|
Here is the description of @value{GDBN} commands related to command
|
|
history.
|
|
|
|
@table @code
|
|
@cindex history substitution
|
|
@cindex history file
|
|
@kindex set history filename
|
|
@cindex @env{GDBHISTFILE}, environment variable
|
|
@item set history filename @var{fname}
|
|
Set the name of the @value{GDBN} command history file to @var{fname}.
|
|
This is the file where @value{GDBN} reads an initial command history
|
|
list, and where it writes the command history from this session when it
|
|
exits. You can access this list through history expansion or through
|
|
the history command editing characters listed below. This file defaults
|
|
to the value of the environment variable @code{GDBHISTFILE}, or to
|
|
@file{./.gdb_history} (@file{./_gdb_history} on MS-DOS) if this variable
|
|
is not set.
|
|
|
|
@cindex save command history
|
|
@kindex set history save
|
|
@item set history save
|
|
@itemx set history save on
|
|
Record command history in a file, whose name may be specified with the
|
|
@code{set history filename} command. By default, this option is disabled.
|
|
|
|
@item set history save off
|
|
Stop recording command history in a file.
|
|
|
|
@cindex history size
|
|
@kindex set history size
|
|
@cindex @env{HISTSIZE}, environment variable
|
|
@item set history size @var{size}
|
|
Set the number of commands which @value{GDBN} keeps in its history list.
|
|
This defaults to the value of the environment variable
|
|
@code{HISTSIZE}, or to 256 if this variable is not set.
|
|
@end table
|
|
|
|
History expansion assigns special meaning to the character @kbd{!}.
|
|
@ifset SYSTEM_READLINE
|
|
@xref{Event Designators, , , history, GNU History Library},
|
|
@end ifset
|
|
@ifclear SYSTEM_READLINE
|
|
@xref{Event Designators},
|
|
@end ifclear
|
|
for more details.
|
|
|
|
@cindex history expansion, turn on/off
|
|
Since @kbd{!} is also the logical not operator in C, history expansion
|
|
is off by default. If you decide to enable history expansion with the
|
|
@code{set history expansion on} command, you may sometimes need to
|
|
follow @kbd{!} (when it is used as logical not, in an expression) with
|
|
a space or a tab to prevent it from being expanded. The readline
|
|
history facilities do not attempt substitution on the strings
|
|
@kbd{!=} and @kbd{!(}, even when history expansion is enabled.
|
|
|
|
The commands to control history expansion are:
|
|
|
|
@table @code
|
|
@item set history expansion on
|
|
@itemx set history expansion
|
|
@kindex set history expansion
|
|
Enable history expansion. History expansion is off by default.
|
|
|
|
@item set history expansion off
|
|
Disable history expansion.
|
|
|
|
@c @group
|
|
@kindex show history
|
|
@item show history
|
|
@itemx show history filename
|
|
@itemx show history save
|
|
@itemx show history size
|
|
@itemx show history expansion
|
|
These commands display the state of the @value{GDBN} history parameters.
|
|
@code{show history} by itself displays all four states.
|
|
@c @end group
|
|
@end table
|
|
|
|
@table @code
|
|
@kindex show commands
|
|
@cindex show last commands
|
|
@cindex display command history
|
|
@item show commands
|
|
Display the last ten commands in the command history.
|
|
|
|
@item show commands @var{n}
|
|
Print ten commands centered on command number @var{n}.
|
|
|
|
@item show commands +
|
|
Print ten commands just after the commands last printed.
|
|
@end table
|
|
|
|
@node Screen Size
|
|
@section Screen Size
|
|
@cindex size of screen
|
|
@cindex pauses in output
|
|
|
|
Certain commands to @value{GDBN} may produce large amounts of
|
|
information output to the screen. To help you read all of it,
|
|
@value{GDBN} pauses and asks you for input at the end of each page of
|
|
output. Type @key{RET} when you want to continue the output, or @kbd{q}
|
|
to discard the remaining output. Also, the screen width setting
|
|
determines when to wrap lines of output. Depending on what is being
|
|
printed, @value{GDBN} tries to break the line at a readable place,
|
|
rather than simply letting it overflow onto the following line.
|
|
|
|
Normally @value{GDBN} knows the size of the screen from the terminal
|
|
driver software. For example, on Unix @value{GDBN} uses the termcap data base
|
|
together with the value of the @code{TERM} environment variable and the
|
|
@code{stty rows} and @code{stty cols} settings. If this is not correct,
|
|
you can override it with the @code{set height} and @code{set
|
|
width} commands:
|
|
|
|
@table @code
|
|
@kindex set height
|
|
@kindex set width
|
|
@kindex show width
|
|
@kindex show height
|
|
@item set height @var{lpp}
|
|
@itemx show height
|
|
@itemx set width @var{cpl}
|
|
@itemx show width
|
|
These @code{set} commands specify a screen height of @var{lpp} lines and
|
|
a screen width of @var{cpl} characters. The associated @code{show}
|
|
commands display the current settings.
|
|
|
|
If you specify a height of zero lines, @value{GDBN} does not pause during
|
|
output no matter how long the output is. This is useful if output is to a
|
|
file or to an editor buffer.
|
|
|
|
Likewise, you can specify @samp{set width 0} to prevent @value{GDBN}
|
|
from wrapping its output.
|
|
|
|
@item set pagination on
|
|
@itemx set pagination off
|
|
@kindex set pagination
|
|
Turn the output pagination on or off; the default is on. Turning
|
|
pagination off is the alternative to @code{set height 0}. Note that
|
|
running @value{GDBN} with the @option{--batch} option (@pxref{Mode
|
|
Options, -batch}) also automatically disables pagination.
|
|
|
|
@item show pagination
|
|
@kindex show pagination
|
|
Show the current pagination mode.
|
|
@end table
|
|
|
|
@node Numbers
|
|
@section Numbers
|
|
@cindex number representation
|
|
@cindex entering numbers
|
|
|
|
You can always enter numbers in octal, decimal, or hexadecimal in
|
|
@value{GDBN} by the usual conventions: octal numbers begin with
|
|
@samp{0}, decimal numbers end with @samp{.}, and hexadecimal numbers
|
|
begin with @samp{0x}. Numbers that neither begin with @samp{0} or
|
|
@samp{0x}, nor end with a @samp{.} are, by default, entered in base
|
|
10; likewise, the default display for numbers---when no particular
|
|
format is specified---is base 10. You can change the default base for
|
|
both input and output with the commands described below.
|
|
|
|
@table @code
|
|
@kindex set input-radix
|
|
@item set input-radix @var{base}
|
|
Set the default base for numeric input. Supported choices
|
|
for @var{base} are decimal 8, 10, or 16. @var{base} must itself be
|
|
specified either unambiguously or using the current input radix; for
|
|
example, any of
|
|
|
|
@smallexample
|
|
set input-radix 012
|
|
set input-radix 10.
|
|
set input-radix 0xa
|
|
@end smallexample
|
|
|
|
@noindent
|
|
sets the input base to decimal. On the other hand, @samp{set input-radix 10}
|
|
leaves the input radix unchanged, no matter what it was, since
|
|
@samp{10}, being without any leading or trailing signs of its base, is
|
|
interpreted in the current radix. Thus, if the current radix is 16,
|
|
@samp{10} is interpreted in hex, i.e.@: as 16 decimal, which doesn't
|
|
change the radix.
|
|
|
|
@kindex set output-radix
|
|
@item set output-radix @var{base}
|
|
Set the default base for numeric display. Supported choices
|
|
for @var{base} are decimal 8, 10, or 16. @var{base} must itself be
|
|
specified either unambiguously or using the current input radix.
|
|
|
|
@kindex show input-radix
|
|
@item show input-radix
|
|
Display the current default base for numeric input.
|
|
|
|
@kindex show output-radix
|
|
@item show output-radix
|
|
Display the current default base for numeric display.
|
|
|
|
@item set radix @r{[}@var{base}@r{]}
|
|
@itemx show radix
|
|
@kindex set radix
|
|
@kindex show radix
|
|
These commands set and show the default base for both input and output
|
|
of numbers. @code{set radix} sets the radix of input and output to
|
|
the same base; without an argument, it resets the radix back to its
|
|
default value of 10.
|
|
|
|
@end table
|
|
|
|
@node ABI
|
|
@section Configuring the Current ABI
|
|
|
|
@value{GDBN} can determine the @dfn{ABI} (Application Binary Interface) of your
|
|
application automatically. However, sometimes you need to override its
|
|
conclusions. Use these commands to manage @value{GDBN}'s view of the
|
|
current ABI.
|
|
|
|
@cindex OS ABI
|
|
@kindex set osabi
|
|
@kindex show osabi
|
|
|
|
One @value{GDBN} configuration can debug binaries for multiple operating
|
|
system targets, either via remote debugging or native emulation.
|
|
@value{GDBN} will autodetect the @dfn{OS ABI} (Operating System ABI) in use,
|
|
but you can override its conclusion using the @code{set osabi} command.
|
|
One example where this is useful is in debugging of binaries which use
|
|
an alternate C library (e.g.@: @sc{uClibc} for @sc{gnu}/Linux) which does
|
|
not have the same identifying marks that the standard C library for your
|
|
platform provides.
|
|
|
|
@table @code
|
|
@item show osabi
|
|
Show the OS ABI currently in use.
|
|
|
|
@item set osabi
|
|
With no argument, show the list of registered available OS ABI's.
|
|
|
|
@item set osabi @var{abi}
|
|
Set the current OS ABI to @var{abi}.
|
|
@end table
|
|
|
|
@cindex float promotion
|
|
|
|
Generally, the way that an argument of type @code{float} is passed to a
|
|
function depends on whether the function is prototyped. For a prototyped
|
|
(i.e.@: ANSI/ISO style) function, @code{float} arguments are passed unchanged,
|
|
according to the architecture's convention for @code{float}. For unprototyped
|
|
(i.e.@: K&R style) functions, @code{float} arguments are first promoted to type
|
|
@code{double} and then passed.
|
|
|
|
Unfortunately, some forms of debug information do not reliably indicate whether
|
|
a function is prototyped. If @value{GDBN} calls a function that is not marked
|
|
as prototyped, it consults @kbd{set coerce-float-to-double}.
|
|
|
|
@table @code
|
|
@kindex set coerce-float-to-double
|
|
@item set coerce-float-to-double
|
|
@itemx set coerce-float-to-double on
|
|
Arguments of type @code{float} will be promoted to @code{double} when passed
|
|
to an unprototyped function. This is the default setting.
|
|
|
|
@item set coerce-float-to-double off
|
|
Arguments of type @code{float} will be passed directly to unprototyped
|
|
functions.
|
|
|
|
@kindex show coerce-float-to-double
|
|
@item show coerce-float-to-double
|
|
Show the current setting of promoting @code{float} to @code{double}.
|
|
@end table
|
|
|
|
@kindex set cp-abi
|
|
@kindex show cp-abi
|
|
@value{GDBN} needs to know the ABI used for your program's C@t{++}
|
|
objects. The correct C@t{++} ABI depends on which C@t{++} compiler was
|
|
used to build your application. @value{GDBN} only fully supports
|
|
programs with a single C@t{++} ABI; if your program contains code using
|
|
multiple C@t{++} ABI's or if @value{GDBN} can not identify your
|
|
program's ABI correctly, you can tell @value{GDBN} which ABI to use.
|
|
Currently supported ABI's include ``gnu-v2'', for @code{g++} versions
|
|
before 3.0, ``gnu-v3'', for @code{g++} versions 3.0 and later, and
|
|
``hpaCC'' for the HP ANSI C@t{++} compiler. Other C@t{++} compilers may
|
|
use the ``gnu-v2'' or ``gnu-v3'' ABI's as well. The default setting is
|
|
``auto''.
|
|
|
|
@table @code
|
|
@item show cp-abi
|
|
Show the C@t{++} ABI currently in use.
|
|
|
|
@item set cp-abi
|
|
With no argument, show the list of supported C@t{++} ABI's.
|
|
|
|
@item set cp-abi @var{abi}
|
|
@itemx set cp-abi auto
|
|
Set the current C@t{++} ABI to @var{abi}, or return to automatic detection.
|
|
@end table
|
|
|
|
@node Auto-loading
|
|
@section Automatically loading associated files
|
|
@cindex auto-loading
|
|
|
|
@value{GDBN} sometimes reads files with commands and settings automatically,
|
|
without being explicitly told so by the user. We call this feature
|
|
@dfn{auto-loading}. While auto-loading is useful for automatically adapting
|
|
@value{GDBN} to the needs of your project, it can sometimes produce unexpected
|
|
results or introduce security risks (e.g., if the file comes from untrusted
|
|
sources).
|
|
|
|
Note that loading of these associated files (including the local @file{.gdbinit}
|
|
file) requires accordingly configured @code{auto-load safe-path}
|
|
(@pxref{Auto-loading safe path}).
|
|
|
|
For these reasons, @value{GDBN} includes commands and options to let you
|
|
control when to auto-load files and which files should be auto-loaded.
|
|
|
|
@table @code
|
|
@anchor{set auto-load off}
|
|
@kindex set auto-load off
|
|
@item set auto-load off
|
|
Globally disable loading of all auto-loaded files.
|
|
You may want to use this command with the @samp{-iex} option
|
|
(@pxref{Option -init-eval-command}) such as:
|
|
@smallexample
|
|
$ @kbd{gdb -iex "set auto-load off" untrusted-executable corefile}
|
|
@end smallexample
|
|
|
|
Be aware that system init file (@pxref{System-wide configuration})
|
|
and init files from your home directory (@pxref{Home Directory Init File})
|
|
still get read (as they come from generally trusted directories).
|
|
To prevent @value{GDBN} from auto-loading even those init files, use the
|
|
@option{-nx} option (@pxref{Mode Options}), in addition to
|
|
@code{set auto-load no}.
|
|
|
|
@anchor{show auto-load}
|
|
@kindex show auto-load
|
|
@item show auto-load
|
|
Show whether auto-loading of each specific @samp{auto-load} file(s) is enabled
|
|
or disabled.
|
|
|
|
@smallexample
|
|
(gdb) show auto-load
|
|
gdb-scripts: Auto-loading of canned sequences of commands scripts is on.
|
|
libthread-db: Auto-loading of inferior specific libthread_db is on.
|
|
local-gdbinit: Auto-loading of .gdbinit script from current directory
|
|
is on.
|
|
python-scripts: Auto-loading of Python scripts is on.
|
|
safe-path: List of directories from which it is safe to auto-load files
|
|
is $debugdir:$datadir/auto-load.
|
|
scripts-directory: List of directories from which to load auto-loaded scripts
|
|
is $debugdir:$datadir/auto-load.
|
|
@end smallexample
|
|
|
|
@anchor{info auto-load}
|
|
@kindex info auto-load
|
|
@item info auto-load
|
|
Print whether each specific @samp{auto-load} file(s) have been auto-loaded or
|
|
not.
|
|
|
|
@smallexample
|
|
(gdb) info auto-load
|
|
gdb-scripts:
|
|
Loaded Script
|
|
Yes /home/user/gdb/gdb-gdb.gdb
|
|
libthread-db: No auto-loaded libthread-db.
|
|
local-gdbinit: Local .gdbinit file "/home/user/gdb/.gdbinit" has been
|
|
loaded.
|
|
python-scripts:
|
|
Loaded Script
|
|
Yes /home/user/gdb/gdb-gdb.py
|
|
@end smallexample
|
|
@end table
|
|
|
|
These are various kinds of files @value{GDBN} can automatically load:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
@xref{objfile-gdb.py file}, controlled by @ref{set auto-load python-scripts}.
|
|
@item
|
|
@xref{objfile-gdb.gdb file}, controlled by @ref{set auto-load gdb-scripts}.
|
|
@item
|
|
@xref{dotdebug_gdb_scripts section},
|
|
controlled by @ref{set auto-load python-scripts}.
|
|
@item
|
|
@xref{Init File in the Current Directory},
|
|
controlled by @ref{set auto-load local-gdbinit}.
|
|
@item
|
|
@xref{libthread_db.so.1 file}, controlled by @ref{set auto-load libthread-db}.
|
|
@end itemize
|
|
|
|
These are @value{GDBN} control commands for the auto-loading:
|
|
|
|
@multitable @columnfractions .5 .5
|
|
@item @xref{set auto-load off}.
|
|
@tab Disable auto-loading globally.
|
|
@item @xref{show auto-load}.
|
|
@tab Show setting of all kinds of files.
|
|
@item @xref{info auto-load}.
|
|
@tab Show state of all kinds of files.
|
|
@item @xref{set auto-load gdb-scripts}.
|
|
@tab Control for @value{GDBN} command scripts.
|
|
@item @xref{show auto-load gdb-scripts}.
|
|
@tab Show setting of @value{GDBN} command scripts.
|
|
@item @xref{info auto-load gdb-scripts}.
|
|
@tab Show state of @value{GDBN} command scripts.
|
|
@item @xref{set auto-load python-scripts}.
|
|
@tab Control for @value{GDBN} Python scripts.
|
|
@item @xref{show auto-load python-scripts}.
|
|
@tab Show setting of @value{GDBN} Python scripts.
|
|
@item @xref{info auto-load python-scripts}.
|
|
@tab Show state of @value{GDBN} Python scripts.
|
|
@item @xref{set auto-load scripts-directory}.
|
|
@tab Control for @value{GDBN} auto-loaded scripts location.
|
|
@item @xref{show auto-load scripts-directory}.
|
|
@tab Show @value{GDBN} auto-loaded scripts location.
|
|
@item @xref{set auto-load local-gdbinit}.
|
|
@tab Control for init file in the current directory.
|
|
@item @xref{show auto-load local-gdbinit}.
|
|
@tab Show setting of init file in the current directory.
|
|
@item @xref{info auto-load local-gdbinit}.
|
|
@tab Show state of init file in the current directory.
|
|
@item @xref{set auto-load libthread-db}.
|
|
@tab Control for thread debugging library.
|
|
@item @xref{show auto-load libthread-db}.
|
|
@tab Show setting of thread debugging library.
|
|
@item @xref{info auto-load libthread-db}.
|
|
@tab Show state of thread debugging library.
|
|
@item @xref{set auto-load safe-path}.
|
|
@tab Control directories trusted for automatic loading.
|
|
@item @xref{show auto-load safe-path}.
|
|
@tab Show directories trusted for automatic loading.
|
|
@item @xref{add-auto-load-safe-path}.
|
|
@tab Add directory trusted for automatic loading.
|
|
@end multitable
|
|
|
|
@menu
|
|
* Init File in the Current Directory:: @samp{set/show/info auto-load local-gdbinit}
|
|
* libthread_db.so.1 file:: @samp{set/show/info auto-load libthread-db}
|
|
* objfile-gdb.gdb file:: @samp{set/show/info auto-load gdb-script}
|
|
* Auto-loading safe path:: @samp{set/show/info auto-load safe-path}
|
|
* Auto-loading verbose mode:: @samp{set/show debug auto-load}
|
|
@xref{Python Auto-loading}.
|
|
@end menu
|
|
|
|
@node Init File in the Current Directory
|
|
@subsection Automatically loading init file in the current directory
|
|
@cindex auto-loading init file in the current directory
|
|
|
|
By default, @value{GDBN} reads and executes the canned sequences of commands
|
|
from init file (if any) in the current working directory,
|
|
see @ref{Init File in the Current Directory during Startup}.
|
|
|
|
Note that loading of this local @file{.gdbinit} file also requires accordingly
|
|
configured @code{auto-load safe-path} (@pxref{Auto-loading safe path}).
|
|
|
|
@table @code
|
|
@anchor{set auto-load local-gdbinit}
|
|
@kindex set auto-load local-gdbinit
|
|
@item set auto-load local-gdbinit [on|off]
|
|
Enable or disable the auto-loading of canned sequences of commands
|
|
(@pxref{Sequences}) found in init file in the current directory.
|
|
|
|
@anchor{show auto-load local-gdbinit}
|
|
@kindex show auto-load local-gdbinit
|
|
@item show auto-load local-gdbinit
|
|
Show whether auto-loading of canned sequences of commands from init file in the
|
|
current directory is enabled or disabled.
|
|
|
|
@anchor{info auto-load local-gdbinit}
|
|
@kindex info auto-load local-gdbinit
|
|
@item info auto-load local-gdbinit
|
|
Print whether canned sequences of commands from init file in the
|
|
current directory have been auto-loaded.
|
|
@end table
|
|
|
|
@node libthread_db.so.1 file
|
|
@subsection Automatically loading thread debugging library
|
|
@cindex auto-loading libthread_db.so.1
|
|
|
|
This feature is currently present only on @sc{gnu}/Linux native hosts.
|
|
|
|
@value{GDBN} reads in some cases thread debugging library from places specific
|
|
to the inferior (@pxref{set libthread-db-search-path}).
|
|
|
|
The special @samp{libthread-db-search-path} entry @samp{$sdir} is processed
|
|
without checking this @samp{set auto-load libthread-db} switch as system
|
|
libraries have to be trusted in general. In all other cases of
|
|
@samp{libthread-db-search-path} entries @value{GDBN} checks first if @samp{set
|
|
auto-load libthread-db} is enabled before trying to open such thread debugging
|
|
library.
|
|
|
|
Note that loading of this debugging library also requires accordingly configured
|
|
@code{auto-load safe-path} (@pxref{Auto-loading safe path}).
|
|
|
|
@table @code
|
|
@anchor{set auto-load libthread-db}
|
|
@kindex set auto-load libthread-db
|
|
@item set auto-load libthread-db [on|off]
|
|
Enable or disable the auto-loading of inferior specific thread debugging library.
|
|
|
|
@anchor{show auto-load libthread-db}
|
|
@kindex show auto-load libthread-db
|
|
@item show auto-load libthread-db
|
|
Show whether auto-loading of inferior specific thread debugging library is
|
|
enabled or disabled.
|
|
|
|
@anchor{info auto-load libthread-db}
|
|
@kindex info auto-load libthread-db
|
|
@item info auto-load libthread-db
|
|
Print the list of all loaded inferior specific thread debugging libraries and
|
|
for each such library print list of inferior @var{pid}s using it.
|
|
@end table
|
|
|
|
@node objfile-gdb.gdb file
|
|
@subsection The @file{@var{objfile}-gdb.gdb} file
|
|
@cindex auto-loading @file{@var{objfile}-gdb.gdb}
|
|
|
|
@value{GDBN} tries to load an @file{@var{objfile}-gdb.gdb} file containing
|
|
canned sequences of commands (@pxref{Sequences}), as long as @samp{set
|
|
auto-load gdb-scripts} is set to @samp{on}.
|
|
|
|
Note that loading of this script file also requires accordingly configured
|
|
@code{auto-load safe-path} (@pxref{Auto-loading safe path}).
|
|
|
|
For more background refer to the similar Python scripts auto-loading
|
|
description (@pxref{objfile-gdb.py file}).
|
|
|
|
@table @code
|
|
@anchor{set auto-load gdb-scripts}
|
|
@kindex set auto-load gdb-scripts
|
|
@item set auto-load gdb-scripts [on|off]
|
|
Enable or disable the auto-loading of canned sequences of commands scripts.
|
|
|
|
@anchor{show auto-load gdb-scripts}
|
|
@kindex show auto-load gdb-scripts
|
|
@item show auto-load gdb-scripts
|
|
Show whether auto-loading of canned sequences of commands scripts is enabled or
|
|
disabled.
|
|
|
|
@anchor{info auto-load gdb-scripts}
|
|
@kindex info auto-load gdb-scripts
|
|
@cindex print list of auto-loaded canned sequences of commands scripts
|
|
@item info auto-load gdb-scripts [@var{regexp}]
|
|
Print the list of all canned sequences of commands scripts that @value{GDBN}
|
|
auto-loaded.
|
|
@end table
|
|
|
|
If @var{regexp} is supplied only canned sequences of commands scripts with
|
|
matching names are printed.
|
|
|
|
@node Auto-loading safe path
|
|
@subsection Security restriction for auto-loading
|
|
@cindex auto-loading safe-path
|
|
|
|
As the files of inferior can come from untrusted source (such as submitted by
|
|
an application user) @value{GDBN} does not always load any files automatically.
|
|
@value{GDBN} provides the @samp{set auto-load safe-path} setting to list
|
|
directories trusted for loading files not explicitly requested by user.
|
|
Each directory can also be a shell wildcard pattern.
|
|
|
|
If the path is not set properly you will see a warning and the file will not
|
|
get loaded:
|
|
|
|
@smallexample
|
|
$ ./gdb -q ./gdb
|
|
Reading symbols from /home/user/gdb/gdb...done.
|
|
warning: File "/home/user/gdb/gdb-gdb.gdb" auto-loading has been
|
|
declined by your `auto-load safe-path' set
|
|
to "$debugdir:$datadir/auto-load".
|
|
warning: File "/home/user/gdb/gdb-gdb.py" auto-loading has been
|
|
declined by your `auto-load safe-path' set
|
|
to "$debugdir:$datadir/auto-load".
|
|
@end smallexample
|
|
|
|
The list of trusted directories is controlled by the following commands:
|
|
|
|
@table @code
|
|
@anchor{set auto-load safe-path}
|
|
@kindex set auto-load safe-path
|
|
@item set auto-load safe-path @r{[}@var{directories}@r{]}
|
|
Set the list of directories (and their subdirectories) trusted for automatic
|
|
loading and execution of scripts. You can also enter a specific trusted file.
|
|
Each directory can also be a shell wildcard pattern; wildcards do not match
|
|
directory separator - see @code{FNM_PATHNAME} for system function @code{fnmatch}
|
|
(@pxref{Wildcard Matching, fnmatch, , libc, GNU C Library Reference Manual}).
|
|
If you omit @var{directories}, @samp{auto-load safe-path} will be reset to
|
|
its default value as specified during @value{GDBN} compilation.
|
|
|
|
The list of directories uses path separator (@samp{:} on GNU and Unix
|
|
systems, @samp{;} on MS-Windows and MS-DOS) to separate directories, similarly
|
|
to the @env{PATH} environment variable.
|
|
|
|
@anchor{show auto-load safe-path}
|
|
@kindex show auto-load safe-path
|
|
@item show auto-load safe-path
|
|
Show the list of directories trusted for automatic loading and execution of
|
|
scripts.
|
|
|
|
@anchor{add-auto-load-safe-path}
|
|
@kindex add-auto-load-safe-path
|
|
@item add-auto-load-safe-path
|
|
Add an entry (or list of entries) the list of directories trusted for automatic
|
|
loading and execution of scripts. Multiple entries may be delimited by the
|
|
host platform path separator in use.
|
|
@end table
|
|
|
|
This variable defaults to what @code{--with-auto-load-dir} has been configured
|
|
to (@pxref{with-auto-load-dir}). @file{$debugdir} and @file{$datadir}
|
|
substitution applies the same as for @ref{set auto-load scripts-directory}.
|
|
The default @code{set auto-load safe-path} value can be also overriden by
|
|
@value{GDBN} configuration option @option{--with-auto-load-safe-path}.
|
|
|
|
Setting this variable to @file{/} disables this security protection,
|
|
corresponding @value{GDBN} configuration option is
|
|
@option{--without-auto-load-safe-path}.
|
|
This variable is supposed to be set to the system directories writable by the
|
|
system superuser only. Users can add their source directories in init files in
|
|
their home directories (@pxref{Home Directory Init File}). See also deprecated
|
|
init file in the current directory
|
|
(@pxref{Init File in the Current Directory during Startup}).
|
|
|
|
To force @value{GDBN} to load the files it declined to load in the previous
|
|
example, you could use one of the following ways:
|
|
|
|
@table @asis
|
|
@item @file{~/.gdbinit}: @samp{add-auto-load-safe-path ~/src/gdb}
|
|
Specify this trusted directory (or a file) as additional component of the list.
|
|
You have to specify also any existing directories displayed by
|
|
by @samp{show auto-load safe-path} (such as @samp{/usr:/bin} in this example).
|
|
|
|
@item @kbd{gdb -iex "set auto-load safe-path /usr:/bin:~/src/gdb" @dots{}}
|
|
Specify this directory as in the previous case but just for a single
|
|
@value{GDBN} session.
|
|
|
|
@item @kbd{gdb -iex "set auto-load safe-path /" @dots{}}
|
|
Disable auto-loading safety for a single @value{GDBN} session.
|
|
This assumes all the files you debug during this @value{GDBN} session will come
|
|
from trusted sources.
|
|
|
|
@item @kbd{./configure --without-auto-load-safe-path}
|
|
During compilation of @value{GDBN} you may disable any auto-loading safety.
|
|
This assumes all the files you will ever debug with this @value{GDBN} come from
|
|
trusted sources.
|
|
@end table
|
|
|
|
On the other hand you can also explicitly forbid automatic files loading which
|
|
also suppresses any such warning messages:
|
|
|
|
@table @asis
|
|
@item @kbd{gdb -iex "set auto-load no" @dots{}}
|
|
You can use @value{GDBN} command-line option for a single @value{GDBN} session.
|
|
|
|
@item @file{~/.gdbinit}: @samp{set auto-load no}
|
|
Disable auto-loading globally for the user
|
|
(@pxref{Home Directory Init File}). While it is improbable, you could also
|
|
use system init file instead (@pxref{System-wide configuration}).
|
|
@end table
|
|
|
|
This setting applies to the file names as entered by user. If no entry matches
|
|
@value{GDBN} tries as a last resort to also resolve all the file names into
|
|
their canonical form (typically resolving symbolic links) and compare the
|
|
entries again. @value{GDBN} already canonicalizes most of the filenames on its
|
|
own before starting the comparison so a canonical form of directories is
|
|
recommended to be entered.
|
|
|
|
@node Auto-loading verbose mode
|
|
@subsection Displaying files tried for auto-load
|
|
@cindex auto-loading verbose mode
|
|
|
|
For better visibility of all the file locations where you can place scripts to
|
|
be auto-loaded with inferior --- or to protect yourself against accidental
|
|
execution of untrusted scripts --- @value{GDBN} provides a feature for printing
|
|
all the files attempted to be loaded. Both existing and non-existing files may
|
|
be printed.
|
|
|
|
For example the list of directories from which it is safe to auto-load files
|
|
(@pxref{Auto-loading safe path}) applies also to canonicalized filenames which
|
|
may not be too obvious while setting it up.
|
|
|
|
@smallexample
|
|
(gdb) set debug auto-load on
|
|
(gdb) file ~/src/t/true
|
|
auto-load: Loading canned sequences of commands script "/tmp/true-gdb.gdb"
|
|
for objfile "/tmp/true".
|
|
auto-load: Updating directories of "/usr:/opt".
|
|
auto-load: Using directory "/usr".
|
|
auto-load: Using directory "/opt".
|
|
warning: File "/tmp/true-gdb.gdb" auto-loading has been declined
|
|
by your `auto-load safe-path' set to "/usr:/opt".
|
|
@end smallexample
|
|
|
|
@table @code
|
|
@anchor{set debug auto-load}
|
|
@kindex set debug auto-load
|
|
@item set debug auto-load [on|off]
|
|
Set whether to print the filenames attempted to be auto-loaded.
|
|
|
|
@anchor{show debug auto-load}
|
|
@kindex show debug auto-load
|
|
@item show debug auto-load
|
|
Show whether printing of the filenames attempted to be auto-loaded is turned
|
|
on or off.
|
|
@end table
|
|
|
|
@node Messages/Warnings
|
|
@section Optional Warnings and Messages
|
|
|
|
@cindex verbose operation
|
|
@cindex optional warnings
|
|
By default, @value{GDBN} is silent about its inner workings. If you are
|
|
running on a slow machine, you may want to use the @code{set verbose}
|
|
command. This makes @value{GDBN} tell you when it does a lengthy
|
|
internal operation, so you will not think it has crashed.
|
|
|
|
Currently, the messages controlled by @code{set verbose} are those
|
|
which announce that the symbol table for a source file is being read;
|
|
see @code{symbol-file} in @ref{Files, ,Commands to Specify Files}.
|
|
|
|
@table @code
|
|
@kindex set verbose
|
|
@item set verbose on
|
|
Enables @value{GDBN} output of certain informational messages.
|
|
|
|
@item set verbose off
|
|
Disables @value{GDBN} output of certain informational messages.
|
|
|
|
@kindex show verbose
|
|
@item show verbose
|
|
Displays whether @code{set verbose} is on or off.
|
|
@end table
|
|
|
|
By default, if @value{GDBN} encounters bugs in the symbol table of an
|
|
object file, it is silent; but if you are debugging a compiler, you may
|
|
find this information useful (@pxref{Symbol Errors, ,Errors Reading
|
|
Symbol Files}).
|
|
|
|
@table @code
|
|
|
|
@kindex set complaints
|
|
@item set complaints @var{limit}
|
|
Permits @value{GDBN} to output @var{limit} complaints about each type of
|
|
unusual symbols before becoming silent about the problem. Set
|
|
@var{limit} to zero to suppress all complaints; set it to a large number
|
|
to prevent complaints from being suppressed.
|
|
|
|
@kindex show complaints
|
|
@item show complaints
|
|
Displays how many symbol complaints @value{GDBN} is permitted to produce.
|
|
|
|
@end table
|
|
|
|
@anchor{confirmation requests}
|
|
By default, @value{GDBN} is cautious, and asks what sometimes seems to be a
|
|
lot of stupid questions to confirm certain commands. For example, if
|
|
you try to run a program which is already running:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) run
|
|
The program being debugged has been started already.
|
|
Start it from the beginning? (y or n)
|
|
@end smallexample
|
|
|
|
If you are willing to unflinchingly face the consequences of your own
|
|
commands, you can disable this ``feature'':
|
|
|
|
@table @code
|
|
|
|
@kindex set confirm
|
|
@cindex flinching
|
|
@cindex confirmation
|
|
@cindex stupid questions
|
|
@item set confirm off
|
|
Disables confirmation requests. Note that running @value{GDBN} with
|
|
the @option{--batch} option (@pxref{Mode Options, -batch}) also
|
|
automatically disables confirmation requests.
|
|
|
|
@item set confirm on
|
|
Enables confirmation requests (the default).
|
|
|
|
@kindex show confirm
|
|
@item show confirm
|
|
Displays state of confirmation requests.
|
|
|
|
@end table
|
|
|
|
@cindex command tracing
|
|
If you need to debug user-defined commands or sourced files you may find it
|
|
useful to enable @dfn{command tracing}. In this mode each command will be
|
|
printed as it is executed, prefixed with one or more @samp{+} symbols, the
|
|
quantity denoting the call depth of each command.
|
|
|
|
@table @code
|
|
@kindex set trace-commands
|
|
@cindex command scripts, debugging
|
|
@item set trace-commands on
|
|
Enable command tracing.
|
|
@item set trace-commands off
|
|
Disable command tracing.
|
|
@item show trace-commands
|
|
Display the current state of command tracing.
|
|
@end table
|
|
|
|
@node Debugging Output
|
|
@section Optional Messages about Internal Happenings
|
|
@cindex optional debugging messages
|
|
|
|
@value{GDBN} has commands that enable optional debugging messages from
|
|
various @value{GDBN} subsystems; normally these commands are of
|
|
interest to @value{GDBN} maintainers, or when reporting a bug. This
|
|
section documents those commands.
|
|
|
|
@table @code
|
|
@kindex set exec-done-display
|
|
@item set exec-done-display
|
|
Turns on or off the notification of asynchronous commands'
|
|
completion. When on, @value{GDBN} will print a message when an
|
|
asynchronous command finishes its execution. The default is off.
|
|
@kindex show exec-done-display
|
|
@item show exec-done-display
|
|
Displays the current setting of asynchronous command completion
|
|
notification.
|
|
@kindex set debug
|
|
@cindex gdbarch debugging info
|
|
@cindex architecture debugging info
|
|
@item set debug arch
|
|
Turns on or off display of gdbarch debugging info. The default is off
|
|
@kindex show debug
|
|
@item show debug arch
|
|
Displays the current state of displaying gdbarch debugging info.
|
|
@item set debug aix-thread
|
|
@cindex AIX threads
|
|
Display debugging messages about inner workings of the AIX thread
|
|
module.
|
|
@item show debug aix-thread
|
|
Show the current state of AIX thread debugging info display.
|
|
@item set debug check-physname
|
|
@cindex physname
|
|
Check the results of the ``physname'' computation. When reading DWARF
|
|
debugging information for C@t{++}, @value{GDBN} attempts to compute
|
|
each entity's name. @value{GDBN} can do this computation in two
|
|
different ways, depending on exactly what information is present.
|
|
When enabled, this setting causes @value{GDBN} to compute the names
|
|
both ways and display any discrepancies.
|
|
@item show debug check-physname
|
|
Show the current state of ``physname'' checking.
|
|
@item set debug dwarf2-die
|
|
@cindex DWARF2 DIEs
|
|
Dump DWARF2 DIEs after they are read in.
|
|
The value is the number of nesting levels to print.
|
|
A value of zero turns off the display.
|
|
@item show debug dwarf2-die
|
|
Show the current state of DWARF2 DIE debugging.
|
|
@item set debug dwarf2-read
|
|
@cindex DWARF2 Reading
|
|
Turns on or off display of debugging messages related to reading
|
|
DWARF debug info. The default is off.
|
|
@item show debug dwarf2-read
|
|
Show the current state of DWARF2 reader debugging.
|
|
@item set debug displaced
|
|
@cindex displaced stepping debugging info
|
|
Turns on or off display of @value{GDBN} debugging info for the
|
|
displaced stepping support. The default is off.
|
|
@item show debug displaced
|
|
Displays the current state of displaying @value{GDBN} debugging info
|
|
related to displaced stepping.
|
|
@item set debug event
|
|
@cindex event debugging info
|
|
Turns on or off display of @value{GDBN} event debugging info. The
|
|
default is off.
|
|
@item show debug event
|
|
Displays the current state of displaying @value{GDBN} event debugging
|
|
info.
|
|
@item set debug expression
|
|
@cindex expression debugging info
|
|
Turns on or off display of debugging info about @value{GDBN}
|
|
expression parsing. The default is off.
|
|
@item show debug expression
|
|
Displays the current state of displaying debugging info about
|
|
@value{GDBN} expression parsing.
|
|
@item set debug frame
|
|
@cindex frame debugging info
|
|
Turns on or off display of @value{GDBN} frame debugging info. The
|
|
default is off.
|
|
@item show debug frame
|
|
Displays the current state of displaying @value{GDBN} frame debugging
|
|
info.
|
|
@item set debug gnu-nat
|
|
@cindex @sc{gnu}/Hurd debug messages
|
|
Turns on or off debugging messages from the @sc{gnu}/Hurd debug support.
|
|
@item show debug gnu-nat
|
|
Show the current state of @sc{gnu}/Hurd debugging messages.
|
|
@item set debug infrun
|
|
@cindex inferior debugging info
|
|
Turns on or off display of @value{GDBN} debugging info for running the inferior.
|
|
The default is off. @file{infrun.c} contains GDB's runtime state machine used
|
|
for implementing operations such as single-stepping the inferior.
|
|
@item show debug infrun
|
|
Displays the current state of @value{GDBN} inferior debugging.
|
|
@item set debug jit
|
|
@cindex just-in-time compilation, debugging messages
|
|
Turns on or off debugging messages from JIT debug support.
|
|
@item show debug jit
|
|
Displays the current state of @value{GDBN} JIT debugging.
|
|
@item set debug lin-lwp
|
|
@cindex @sc{gnu}/Linux LWP debug messages
|
|
@cindex Linux lightweight processes
|
|
Turns on or off debugging messages from the Linux LWP debug support.
|
|
@item show debug lin-lwp
|
|
Show the current state of Linux LWP debugging messages.
|
|
@item set debug observer
|
|
@cindex observer debugging info
|
|
Turns on or off display of @value{GDBN} observer debugging. This
|
|
includes info such as the notification of observable events.
|
|
@item show debug observer
|
|
Displays the current state of observer debugging.
|
|
@item set debug overload
|
|
@cindex C@t{++} overload debugging info
|
|
Turns on or off display of @value{GDBN} C@t{++} overload debugging
|
|
info. This includes info such as ranking of functions, etc. The default
|
|
is off.
|
|
@item show debug overload
|
|
Displays the current state of displaying @value{GDBN} C@t{++} overload
|
|
debugging info.
|
|
@cindex expression parser, debugging info
|
|
@cindex debug expression parser
|
|
@item set debug parser
|
|
Turns on or off the display of expression parser debugging output.
|
|
Internally, this sets the @code{yydebug} variable in the expression
|
|
parser. @xref{Tracing, , Tracing Your Parser, bison, Bison}, for
|
|
details. The default is off.
|
|
@item show debug parser
|
|
Show the current state of expression parser debugging.
|
|
@cindex packets, reporting on stdout
|
|
@cindex serial connections, debugging
|
|
@cindex debug remote protocol
|
|
@cindex remote protocol debugging
|
|
@cindex display remote packets
|
|
@item set debug remote
|
|
Turns on or off display of reports on all packets sent back and forth across
|
|
the serial line to the remote machine. The info is printed on the
|
|
@value{GDBN} standard output stream. The default is off.
|
|
@item show debug remote
|
|
Displays the state of display of remote packets.
|
|
@item set debug serial
|
|
Turns on or off display of @value{GDBN} serial debugging info. The
|
|
default is off.
|
|
@item show debug serial
|
|
Displays the current state of displaying @value{GDBN} serial debugging
|
|
info.
|
|
@item set debug solib-frv
|
|
@cindex FR-V shared-library debugging
|
|
Turns on or off debugging messages for FR-V shared-library code.
|
|
@item show debug solib-frv
|
|
Display the current state of FR-V shared-library code debugging
|
|
messages.
|
|
@item set debug symtab-create
|
|
@cindex symbol table creation
|
|
Turns on or off display of debugging messages related to symbol table creation.
|
|
The default is off.
|
|
@item show debug symtab-create
|
|
Show the current state of symbol table creation debugging.
|
|
@item set debug target
|
|
@cindex target debugging info
|
|
Turns on or off display of @value{GDBN} target debugging info. This info
|
|
includes what is going on at the target level of GDB, as it happens. The
|
|
default is 0. Set it to 1 to track events, and to 2 to also track the
|
|
value of large memory transfers. Changes to this flag do not take effect
|
|
until the next time you connect to a target or use the @code{run} command.
|
|
@item show debug target
|
|
Displays the current state of displaying @value{GDBN} target debugging
|
|
info.
|
|
@item set debug timestamp
|
|
@cindex timestampping debugging info
|
|
Turns on or off display of timestamps with @value{GDBN} debugging info.
|
|
When enabled, seconds and microseconds are displayed before each debugging
|
|
message.
|
|
@item show debug timestamp
|
|
Displays the current state of displaying timestamps with @value{GDBN}
|
|
debugging info.
|
|
@item set debugvarobj
|
|
@cindex variable object debugging info
|
|
Turns on or off display of @value{GDBN} variable object debugging
|
|
info. The default is off.
|
|
@item show debugvarobj
|
|
Displays the current state of displaying @value{GDBN} variable object
|
|
debugging info.
|
|
@item set debug xml
|
|
@cindex XML parser debugging
|
|
Turns on or off debugging messages for built-in XML parsers.
|
|
@item show debug xml
|
|
Displays the current state of XML debugging messages.
|
|
@end table
|
|
|
|
@node Other Misc Settings
|
|
@section Other Miscellaneous Settings
|
|
@cindex miscellaneous settings
|
|
|
|
@table @code
|
|
@kindex set interactive-mode
|
|
@item set interactive-mode
|
|
If @code{on}, forces @value{GDBN} to assume that GDB was started
|
|
in a terminal. In practice, this means that @value{GDBN} should wait
|
|
for the user to answer queries generated by commands entered at
|
|
the command prompt. If @code{off}, forces @value{GDBN} to operate
|
|
in the opposite mode, and it uses the default answers to all queries.
|
|
If @code{auto} (the default), @value{GDBN} tries to determine whether
|
|
its standard input is a terminal, and works in interactive-mode if it
|
|
is, non-interactively otherwise.
|
|
|
|
In the vast majority of cases, the debugger should be able to guess
|
|
correctly which mode should be used. But this setting can be useful
|
|
in certain specific cases, such as running a MinGW @value{GDBN}
|
|
inside a cygwin window.
|
|
|
|
@kindex show interactive-mode
|
|
@item show interactive-mode
|
|
Displays whether the debugger is operating in interactive mode or not.
|
|
@end table
|
|
|
|
@node Extending GDB
|
|
@chapter Extending @value{GDBN}
|
|
@cindex extending GDB
|
|
|
|
@value{GDBN} provides three mechanisms for extension. The first is based
|
|
on composition of @value{GDBN} commands, the second is based on the
|
|
Python scripting language, and the third is for defining new aliases of
|
|
existing commands.
|
|
|
|
To facilitate the use of the first two extensions, @value{GDBN} is capable
|
|
of evaluating the contents of a file. When doing so, @value{GDBN}
|
|
can recognize which scripting language is being used by looking at
|
|
the filename extension. Files with an unrecognized filename extension
|
|
are always treated as a @value{GDBN} Command Files.
|
|
@xref{Command Files,, Command files}.
|
|
|
|
You can control how @value{GDBN} evaluates these files with the following
|
|
setting:
|
|
|
|
@table @code
|
|
@kindex set script-extension
|
|
@kindex show script-extension
|
|
@item set script-extension off
|
|
All scripts are always evaluated as @value{GDBN} Command Files.
|
|
|
|
@item set script-extension soft
|
|
The debugger determines the scripting language based on filename
|
|
extension. If this scripting language is supported, @value{GDBN}
|
|
evaluates the script using that language. Otherwise, it evaluates
|
|
the file as a @value{GDBN} Command File.
|
|
|
|
@item set script-extension strict
|
|
The debugger determines the scripting language based on filename
|
|
extension, and evaluates the script using that language. If the
|
|
language is not supported, then the evaluation fails.
|
|
|
|
@item show script-extension
|
|
Display the current value of the @code{script-extension} option.
|
|
|
|
@end table
|
|
|
|
@menu
|
|
* Sequences:: Canned Sequences of Commands
|
|
* Python:: Scripting @value{GDBN} using Python
|
|
* Aliases:: Creating new spellings of existing commands
|
|
@end menu
|
|
|
|
@node Sequences
|
|
@section Canned Sequences of Commands
|
|
|
|
Aside from breakpoint commands (@pxref{Break Commands, ,Breakpoint
|
|
Command Lists}), @value{GDBN} provides two ways to store sequences of
|
|
commands for execution as a unit: user-defined commands and command
|
|
files.
|
|
|
|
@menu
|
|
* Define:: How to define your own commands
|
|
* Hooks:: Hooks for user-defined commands
|
|
* Command Files:: How to write scripts of commands to be stored in a file
|
|
* Output:: Commands for controlled output
|
|
@end menu
|
|
|
|
@node Define
|
|
@subsection User-defined Commands
|
|
|
|
@cindex user-defined command
|
|
@cindex arguments, to user-defined commands
|
|
A @dfn{user-defined command} is a sequence of @value{GDBN} commands to
|
|
which you assign a new name as a command. This is done with the
|
|
@code{define} command. User commands may accept up to 10 arguments
|
|
separated by whitespace. Arguments are accessed within the user command
|
|
via @code{$arg0@dots{}$arg9}. A trivial example:
|
|
|
|
@smallexample
|
|
define adder
|
|
print $arg0 + $arg1 + $arg2
|
|
end
|
|
@end smallexample
|
|
|
|
@noindent
|
|
To execute the command use:
|
|
|
|
@smallexample
|
|
adder 1 2 3
|
|
@end smallexample
|
|
|
|
@noindent
|
|
This defines the command @code{adder}, which prints the sum of
|
|
its three arguments. Note the arguments are text substitutions, so they may
|
|
reference variables, use complex expressions, or even perform inferior
|
|
functions calls.
|
|
|
|
@cindex argument count in user-defined commands
|
|
@cindex how many arguments (user-defined commands)
|
|
In addition, @code{$argc} may be used to find out how many arguments have
|
|
been passed. This expands to a number in the range 0@dots{}10.
|
|
|
|
@smallexample
|
|
define adder
|
|
if $argc == 2
|
|
print $arg0 + $arg1
|
|
end
|
|
if $argc == 3
|
|
print $arg0 + $arg1 + $arg2
|
|
end
|
|
end
|
|
@end smallexample
|
|
|
|
@table @code
|
|
|
|
@kindex define
|
|
@item define @var{commandname}
|
|
Define a command named @var{commandname}. If there is already a command
|
|
by that name, you are asked to confirm that you want to redefine it.
|
|
@var{commandname} may be a bare command name consisting of letters,
|
|
numbers, dashes, and underscores. It may also start with any predefined
|
|
prefix command. For example, @samp{define target my-target} creates
|
|
a user-defined @samp{target my-target} command.
|
|
|
|
The definition of the command is made up of other @value{GDBN} command lines,
|
|
which are given following the @code{define} command. The end of these
|
|
commands is marked by a line containing @code{end}.
|
|
|
|
@kindex document
|
|
@kindex end@r{ (user-defined commands)}
|
|
@item document @var{commandname}
|
|
Document the user-defined command @var{commandname}, so that it can be
|
|
accessed by @code{help}. The command @var{commandname} must already be
|
|
defined. This command reads lines of documentation just as @code{define}
|
|
reads the lines of the command definition, ending with @code{end}.
|
|
After the @code{document} command is finished, @code{help} on command
|
|
@var{commandname} displays the documentation you have written.
|
|
|
|
You may use the @code{document} command again to change the
|
|
documentation of a command. Redefining the command with @code{define}
|
|
does not change the documentation.
|
|
|
|
@kindex dont-repeat
|
|
@cindex don't repeat command
|
|
@item dont-repeat
|
|
Used inside a user-defined command, this tells @value{GDBN} that this
|
|
command should not be repeated when the user hits @key{RET}
|
|
(@pxref{Command Syntax, repeat last command}).
|
|
|
|
@kindex help user-defined
|
|
@item help user-defined
|
|
List all user-defined commands and all python commands defined in class
|
|
COMAND_USER. The first line of the documentation or docstring is
|
|
included (if any).
|
|
|
|
@kindex show user
|
|
@item show user
|
|
@itemx show user @var{commandname}
|
|
Display the @value{GDBN} commands used to define @var{commandname} (but
|
|
not its documentation). If no @var{commandname} is given, display the
|
|
definitions for all user-defined commands.
|
|
This does not work for user-defined python commands.
|
|
|
|
@cindex infinite recursion in user-defined commands
|
|
@kindex show max-user-call-depth
|
|
@kindex set max-user-call-depth
|
|
@item show max-user-call-depth
|
|
@itemx set max-user-call-depth
|
|
The value of @code{max-user-call-depth} controls how many recursion
|
|
levels are allowed in user-defined commands before @value{GDBN} suspects an
|
|
infinite recursion and aborts the command.
|
|
This does not apply to user-defined python commands.
|
|
@end table
|
|
|
|
In addition to the above commands, user-defined commands frequently
|
|
use control flow commands, described in @ref{Command Files}.
|
|
|
|
When user-defined commands are executed, the
|
|
commands of the definition are not printed. An error in any command
|
|
stops execution of the user-defined command.
|
|
|
|
If used interactively, commands that would ask for confirmation proceed
|
|
without asking when used inside a user-defined command. Many @value{GDBN}
|
|
commands that normally print messages to say what they are doing omit the
|
|
messages when used in a user-defined command.
|
|
|
|
@node Hooks
|
|
@subsection User-defined Command Hooks
|
|
@cindex command hooks
|
|
@cindex hooks, for commands
|
|
@cindex hooks, pre-command
|
|
|
|
@kindex hook
|
|
You may define @dfn{hooks}, which are a special kind of user-defined
|
|
command. Whenever you run the command @samp{foo}, if the user-defined
|
|
command @samp{hook-foo} exists, it is executed (with no arguments)
|
|
before that command.
|
|
|
|
@cindex hooks, post-command
|
|
@kindex hookpost
|
|
A hook may also be defined which is run after the command you executed.
|
|
Whenever you run the command @samp{foo}, if the user-defined command
|
|
@samp{hookpost-foo} exists, it is executed (with no arguments) after
|
|
that command. Post-execution hooks may exist simultaneously with
|
|
pre-execution hooks, for the same command.
|
|
|
|
It is valid for a hook to call the command which it hooks. If this
|
|
occurs, the hook is not re-executed, thereby avoiding infinite recursion.
|
|
|
|
@c It would be nice if hookpost could be passed a parameter indicating
|
|
@c if the command it hooks executed properly or not. FIXME!
|
|
|
|
@kindex stop@r{, a pseudo-command}
|
|
In addition, a pseudo-command, @samp{stop} exists. Defining
|
|
(@samp{hook-stop}) makes the associated commands execute every time
|
|
execution stops in your program: before breakpoint commands are run,
|
|
displays are printed, or the stack frame is printed.
|
|
|
|
For example, to ignore @code{SIGALRM} signals while
|
|
single-stepping, but treat them normally during normal execution,
|
|
you could define:
|
|
|
|
@smallexample
|
|
define hook-stop
|
|
handle SIGALRM nopass
|
|
end
|
|
|
|
define hook-run
|
|
handle SIGALRM pass
|
|
end
|
|
|
|
define hook-continue
|
|
handle SIGALRM pass
|
|
end
|
|
@end smallexample
|
|
|
|
As a further example, to hook at the beginning and end of the @code{echo}
|
|
command, and to add extra text to the beginning and end of the message,
|
|
you could define:
|
|
|
|
@smallexample
|
|
define hook-echo
|
|
echo <<<---
|
|
end
|
|
|
|
define hookpost-echo
|
|
echo --->>>\n
|
|
end
|
|
|
|
(@value{GDBP}) echo Hello World
|
|
<<<---Hello World--->>>
|
|
(@value{GDBP})
|
|
|
|
@end smallexample
|
|
|
|
You can define a hook for any single-word command in @value{GDBN}, but
|
|
not for command aliases; you should define a hook for the basic command
|
|
name, e.g.@: @code{backtrace} rather than @code{bt}.
|
|
@c FIXME! So how does Joe User discover whether a command is an alias
|
|
@c or not?
|
|
You can hook a multi-word command by adding @code{hook-} or
|
|
@code{hookpost-} to the last word of the command, e.g.@:
|
|
@samp{define target hook-remote} to add a hook to @samp{target remote}.
|
|
|
|
If an error occurs during the execution of your hook, execution of
|
|
@value{GDBN} commands stops and @value{GDBN} issues a prompt
|
|
(before the command that you actually typed had a chance to run).
|
|
|
|
If you try to define a hook which does not match any known command, you
|
|
get a warning from the @code{define} command.
|
|
|
|
@node Command Files
|
|
@subsection Command Files
|
|
|
|
@cindex command files
|
|
@cindex scripting commands
|
|
A command file for @value{GDBN} is a text file made of lines that are
|
|
@value{GDBN} commands. Comments (lines starting with @kbd{#}) may
|
|
also be included. An empty line in a command file does nothing; it
|
|
does not mean to repeat the last command, as it would from the
|
|
terminal.
|
|
|
|
You can request the execution of a command file with the @code{source}
|
|
command. Note that the @code{source} command is also used to evaluate
|
|
scripts that are not Command Files. The exact behavior can be configured
|
|
using the @code{script-extension} setting.
|
|
@xref{Extending GDB,, Extending GDB}.
|
|
|
|
@table @code
|
|
@kindex source
|
|
@cindex execute commands from a file
|
|
@item source [-s] [-v] @var{filename}
|
|
Execute the command file @var{filename}.
|
|
@end table
|
|
|
|
The lines in a command file are generally executed sequentially,
|
|
unless the order of execution is changed by one of the
|
|
@emph{flow-control commands} described below. The commands are not
|
|
printed as they are executed. An error in any command terminates
|
|
execution of the command file and control is returned to the console.
|
|
|
|
@value{GDBN} first searches for @var{filename} in the current directory.
|
|
If the file is not found there, and @var{filename} does not specify a
|
|
directory, then @value{GDBN} also looks for the file on the source search path
|
|
(specified with the @samp{directory} command);
|
|
except that @file{$cdir} is not searched because the compilation directory
|
|
is not relevant to scripts.
|
|
|
|
If @code{-s} is specified, then @value{GDBN} searches for @var{filename}
|
|
on the search path even if @var{filename} specifies a directory.
|
|
The search is done by appending @var{filename} to each element of the
|
|
search path. So, for example, if @var{filename} is @file{mylib/myscript}
|
|
and the search path contains @file{/home/user} then @value{GDBN} will
|
|
look for the script @file{/home/user/mylib/myscript}.
|
|
The search is also done if @var{filename} is an absolute path.
|
|
For example, if @var{filename} is @file{/tmp/myscript} and
|
|
the search path contains @file{/home/user} then @value{GDBN} will
|
|
look for the script @file{/home/user/tmp/myscript}.
|
|
For DOS-like systems, if @var{filename} contains a drive specification,
|
|
it is stripped before concatenation. For example, if @var{filename} is
|
|
@file{d:myscript} and the search path contains @file{c:/tmp} then @value{GDBN}
|
|
will look for the script @file{c:/tmp/myscript}.
|
|
|
|
If @code{-v}, for verbose mode, is given then @value{GDBN} displays
|
|
each command as it is executed. The option must be given before
|
|
@var{filename}, and is interpreted as part of the filename anywhere else.
|
|
|
|
Commands that would ask for confirmation if used interactively proceed
|
|
without asking when used in a command file. Many @value{GDBN} commands that
|
|
normally print messages to say what they are doing omit the messages
|
|
when called from command files.
|
|
|
|
@value{GDBN} also accepts command input from standard input. In this
|
|
mode, normal output goes to standard output and error output goes to
|
|
standard error. Errors in a command file supplied on standard input do
|
|
not terminate execution of the command file---execution continues with
|
|
the next command.
|
|
|
|
@smallexample
|
|
gdb < cmds > log 2>&1
|
|
@end smallexample
|
|
|
|
(The syntax above will vary depending on the shell used.) This example
|
|
will execute commands from the file @file{cmds}. All output and errors
|
|
would be directed to @file{log}.
|
|
|
|
Since commands stored on command files tend to be more general than
|
|
commands typed interactively, they frequently need to deal with
|
|
complicated situations, such as different or unexpected values of
|
|
variables and symbols, changes in how the program being debugged is
|
|
built, etc. @value{GDBN} provides a set of flow-control commands to
|
|
deal with these complexities. Using these commands, you can write
|
|
complex scripts that loop over data structures, execute commands
|
|
conditionally, etc.
|
|
|
|
@table @code
|
|
@kindex if
|
|
@kindex else
|
|
@item if
|
|
@itemx else
|
|
This command allows to include in your script conditionally executed
|
|
commands. The @code{if} command takes a single argument, which is an
|
|
expression to evaluate. It is followed by a series of commands that
|
|
are executed only if the expression is true (its value is nonzero).
|
|
There can then optionally be an @code{else} line, followed by a series
|
|
of commands that are only executed if the expression was false. The
|
|
end of the list is marked by a line containing @code{end}.
|
|
|
|
@kindex while
|
|
@item while
|
|
This command allows to write loops. Its syntax is similar to
|
|
@code{if}: the command takes a single argument, which is an expression
|
|
to evaluate, and must be followed by the commands to execute, one per
|
|
line, terminated by an @code{end}. These commands are called the
|
|
@dfn{body} of the loop. The commands in the body of @code{while} are
|
|
executed repeatedly as long as the expression evaluates to true.
|
|
|
|
@kindex loop_break
|
|
@item loop_break
|
|
This command exits the @code{while} loop in whose body it is included.
|
|
Execution of the script continues after that @code{while}s @code{end}
|
|
line.
|
|
|
|
@kindex loop_continue
|
|
@item loop_continue
|
|
This command skips the execution of the rest of the body of commands
|
|
in the @code{while} loop in whose body it is included. Execution
|
|
branches to the beginning of the @code{while} loop, where it evaluates
|
|
the controlling expression.
|
|
|
|
@kindex end@r{ (if/else/while commands)}
|
|
@item end
|
|
Terminate the block of commands that are the body of @code{if},
|
|
@code{else}, or @code{while} flow-control commands.
|
|
@end table
|
|
|
|
|
|
@node Output
|
|
@subsection Commands for Controlled Output
|
|
|
|
During the execution of a command file or a user-defined command, normal
|
|
@value{GDBN} output is suppressed; the only output that appears is what is
|
|
explicitly printed by the commands in the definition. This section
|
|
describes three commands useful for generating exactly the output you
|
|
want.
|
|
|
|
@table @code
|
|
@kindex echo
|
|
@item echo @var{text}
|
|
@c I do not consider backslash-space a standard C escape sequence
|
|
@c because it is not in ANSI.
|
|
Print @var{text}. Nonprinting characters can be included in
|
|
@var{text} using C escape sequences, such as @samp{\n} to print a
|
|
newline. @strong{No newline is printed unless you specify one.}
|
|
In addition to the standard C escape sequences, a backslash followed
|
|
by a space stands for a space. This is useful for displaying a
|
|
string with spaces at the beginning or the end, since leading and
|
|
trailing spaces are otherwise trimmed from all arguments.
|
|
To print @samp{@w{ }and foo =@w{ }}, use the command
|
|
@samp{echo \@w{ }and foo = \@w{ }}.
|
|
|
|
A backslash at the end of @var{text} can be used, as in C, to continue
|
|
the command onto subsequent lines. For example,
|
|
|
|
@smallexample
|
|
echo This is some text\n\
|
|
which is continued\n\
|
|
onto several lines.\n
|
|
@end smallexample
|
|
|
|
produces the same output as
|
|
|
|
@smallexample
|
|
echo This is some text\n
|
|
echo which is continued\n
|
|
echo onto several lines.\n
|
|
@end smallexample
|
|
|
|
@kindex output
|
|
@item output @var{expression}
|
|
Print the value of @var{expression} and nothing but that value: no
|
|
newlines, no @samp{$@var{nn} = }. The value is not entered in the
|
|
value history either. @xref{Expressions, ,Expressions}, for more information
|
|
on expressions.
|
|
|
|
@item output/@var{fmt} @var{expression}
|
|
Print the value of @var{expression} in format @var{fmt}. You can use
|
|
the same formats as for @code{print}. @xref{Output Formats,,Output
|
|
Formats}, for more information.
|
|
|
|
@kindex printf
|
|
@item printf @var{template}, @var{expressions}@dots{}
|
|
Print the values of one or more @var{expressions} under the control of
|
|
the string @var{template}. To print several values, make
|
|
@var{expressions} be a comma-separated list of individual expressions,
|
|
which may be either numbers or pointers. Their values are printed as
|
|
specified by @var{template}, exactly as a C program would do by
|
|
executing the code below:
|
|
|
|
@smallexample
|
|
printf (@var{template}, @var{expressions}@dots{});
|
|
@end smallexample
|
|
|
|
As in @code{C} @code{printf}, ordinary characters in @var{template}
|
|
are printed verbatim, while @dfn{conversion specification} introduced
|
|
by the @samp{%} character cause subsequent @var{expressions} to be
|
|
evaluated, their values converted and formatted according to type and
|
|
style information encoded in the conversion specifications, and then
|
|
printed.
|
|
|
|
For example, you can print two values in hex like this:
|
|
|
|
@smallexample
|
|
printf "foo, bar-foo = 0x%x, 0x%x\n", foo, bar-foo
|
|
@end smallexample
|
|
|
|
@code{printf} supports all the standard @code{C} conversion
|
|
specifications, including the flags and modifiers between the @samp{%}
|
|
character and the conversion letter, with the following exceptions:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
The argument-ordering modifiers, such as @samp{2$}, are not supported.
|
|
|
|
@item
|
|
The modifier @samp{*} is not supported for specifying precision or
|
|
width.
|
|
|
|
@item
|
|
The @samp{'} flag (for separation of digits into groups according to
|
|
@code{LC_NUMERIC'}) is not supported.
|
|
|
|
@item
|
|
The type modifiers @samp{hh}, @samp{j}, @samp{t}, and @samp{z} are not
|
|
supported.
|
|
|
|
@item
|
|
The conversion letter @samp{n} (as in @samp{%n}) is not supported.
|
|
|
|
@item
|
|
The conversion letters @samp{a} and @samp{A} are not supported.
|
|
@end itemize
|
|
|
|
@noindent
|
|
Note that the @samp{ll} type modifier is supported only if the
|
|
underlying @code{C} implementation used to build @value{GDBN} supports
|
|
the @code{long long int} type, and the @samp{L} type modifier is
|
|
supported only if @code{long double} type is available.
|
|
|
|
As in @code{C}, @code{printf} supports simple backslash-escape
|
|
sequences, such as @code{\n}, @samp{\t}, @samp{\\}, @samp{\"},
|
|
@samp{\a}, and @samp{\f}, that consist of backslash followed by a
|
|
single character. Octal and hexadecimal escape sequences are not
|
|
supported.
|
|
|
|
Additionally, @code{printf} supports conversion specifications for DFP
|
|
(@dfn{Decimal Floating Point}) types using the following length modifiers
|
|
together with a floating point specifier.
|
|
letters:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
@samp{H} for printing @code{Decimal32} types.
|
|
|
|
@item
|
|
@samp{D} for printing @code{Decimal64} types.
|
|
|
|
@item
|
|
@samp{DD} for printing @code{Decimal128} types.
|
|
@end itemize
|
|
|
|
If the underlying @code{C} implementation used to build @value{GDBN} has
|
|
support for the three length modifiers for DFP types, other modifiers
|
|
such as width and precision will also be available for @value{GDBN} to use.
|
|
|
|
In case there is no such @code{C} support, no additional modifiers will be
|
|
available and the value will be printed in the standard way.
|
|
|
|
Here's an example of printing DFP types using the above conversion letters:
|
|
@smallexample
|
|
printf "D32: %Hf - D64: %Df - D128: %DDf\n",1.2345df,1.2E10dd,1.2E1dl
|
|
@end smallexample
|
|
|
|
@kindex eval
|
|
@item eval @var{template}, @var{expressions}@dots{}
|
|
Convert the values of one or more @var{expressions} under the control of
|
|
the string @var{template} to a command line, and call it.
|
|
|
|
@end table
|
|
|
|
@node Python
|
|
@section Scripting @value{GDBN} using Python
|
|
@cindex python scripting
|
|
@cindex scripting with python
|
|
|
|
You can script @value{GDBN} using the @uref{http://www.python.org/,
|
|
Python programming language}. This feature is available only if
|
|
@value{GDBN} was configured using @option{--with-python}.
|
|
|
|
@cindex python directory
|
|
Python scripts used by @value{GDBN} should be installed in
|
|
@file{@var{data-directory}/python}, where @var{data-directory} is
|
|
the data directory as determined at @value{GDBN} startup (@pxref{Data Files}).
|
|
This directory, known as the @dfn{python directory},
|
|
is automatically added to the Python Search Path in order to allow
|
|
the Python interpreter to locate all scripts installed at this location.
|
|
|
|
Additionally, @value{GDBN} commands and convenience functions which
|
|
are written in Python and are located in the
|
|
@file{@var{data-directory}/python/gdb/command} or
|
|
@file{@var{data-directory}/python/gdb/function} directories are
|
|
automatically imported when @value{GDBN} starts.
|
|
|
|
@menu
|
|
* Python Commands:: Accessing Python from @value{GDBN}.
|
|
* Python API:: Accessing @value{GDBN} from Python.
|
|
* Python Auto-loading:: Automatically loading Python code.
|
|
* Python modules:: Python modules provided by @value{GDBN}.
|
|
@end menu
|
|
|
|
@node Python Commands
|
|
@subsection Python Commands
|
|
@cindex python commands
|
|
@cindex commands to access python
|
|
|
|
@value{GDBN} provides one command for accessing the Python interpreter,
|
|
and one related setting:
|
|
|
|
@table @code
|
|
@kindex python
|
|
@item python @r{[}@var{code}@r{]}
|
|
The @code{python} command can be used to evaluate Python code.
|
|
|
|
If given an argument, the @code{python} command will evaluate the
|
|
argument as a Python command. For example:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) python print 23
|
|
23
|
|
@end smallexample
|
|
|
|
If you do not provide an argument to @code{python}, it will act as a
|
|
multi-line command, like @code{define}. In this case, the Python
|
|
script is made up of subsequent command lines, given after the
|
|
@code{python} command. This command list is terminated using a line
|
|
containing @code{end}. For example:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) python
|
|
Type python script
|
|
End with a line saying just "end".
|
|
>print 23
|
|
>end
|
|
23
|
|
@end smallexample
|
|
|
|
@kindex set python print-stack
|
|
@item set python print-stack
|
|
By default, @value{GDBN} will print only the message component of a
|
|
Python exception when an error occurs in a Python script. This can be
|
|
controlled using @code{set python print-stack}: if @code{full}, then
|
|
full Python stack printing is enabled; if @code{none}, then Python stack
|
|
and message printing is disabled; if @code{message}, the default, only
|
|
the message component of the error is printed.
|
|
@end table
|
|
|
|
It is also possible to execute a Python script from the @value{GDBN}
|
|
interpreter:
|
|
|
|
@table @code
|
|
@item source @file{script-name}
|
|
The script name must end with @samp{.py} and @value{GDBN} must be configured
|
|
to recognize the script language based on filename extension using
|
|
the @code{script-extension} setting. @xref{Extending GDB, ,Extending GDB}.
|
|
|
|
@item python execfile ("script-name")
|
|
This method is based on the @code{execfile} Python built-in function,
|
|
and thus is always available.
|
|
@end table
|
|
|
|
@node Python API
|
|
@subsection Python API
|
|
@cindex python api
|
|
@cindex programming in python
|
|
|
|
@cindex python stdout
|
|
@cindex python pagination
|
|
At startup, @value{GDBN} overrides Python's @code{sys.stdout} and
|
|
@code{sys.stderr} to print using @value{GDBN}'s output-paging streams.
|
|
A Python program which outputs to one of these streams may have its
|
|
output interrupted by the user (@pxref{Screen Size}). In this
|
|
situation, a Python @code{KeyboardInterrupt} exception is thrown.
|
|
|
|
@menu
|
|
* Basic Python:: Basic Python Functions.
|
|
* Exception Handling:: How Python exceptions are translated.
|
|
* Values From Inferior:: Python representation of values.
|
|
* Types In Python:: Python representation of types.
|
|
* Pretty Printing API:: Pretty-printing values.
|
|
* Selecting Pretty-Printers:: How GDB chooses a pretty-printer.
|
|
* Writing a Pretty-Printer:: Writing a Pretty-Printer.
|
|
* Inferiors In Python:: Python representation of inferiors (processes)
|
|
* Events In Python:: Listening for events from @value{GDBN}.
|
|
* Threads In Python:: Accessing inferior threads from Python.
|
|
* Commands In Python:: Implementing new commands in Python.
|
|
* Parameters In Python:: Adding new @value{GDBN} parameters.
|
|
* Functions In Python:: Writing new convenience functions.
|
|
* Progspaces In Python:: Program spaces.
|
|
* Objfiles In Python:: Object files.
|
|
* Frames In Python:: Accessing inferior stack frames from Python.
|
|
* Blocks In Python:: Accessing frame blocks from Python.
|
|
* Symbols In Python:: Python representation of symbols.
|
|
* Symbol Tables In Python:: Python representation of symbol tables.
|
|
* Breakpoints In Python:: Manipulating breakpoints using Python.
|
|
* Finish Breakpoints in Python:: Setting Breakpoints on function return
|
|
using Python.
|
|
* Lazy Strings In Python:: Python representation of lazy strings.
|
|
@end menu
|
|
|
|
@node Basic Python
|
|
@subsubsection Basic Python
|
|
|
|
@cindex python functions
|
|
@cindex python module
|
|
@cindex gdb module
|
|
@value{GDBN} introduces a new Python module, named @code{gdb}. All
|
|
methods and classes added by @value{GDBN} are placed in this module.
|
|
@value{GDBN} automatically @code{import}s the @code{gdb} module for
|
|
use in all scripts evaluated by the @code{python} command.
|
|
|
|
@findex gdb.PYTHONDIR
|
|
@defvar gdb.PYTHONDIR
|
|
A string containing the python directory (@pxref{Python}).
|
|
@end defvar
|
|
|
|
@findex gdb.execute
|
|
@defun gdb.execute (command @r{[}, from_tty @r{[}, to_string@r{]]})
|
|
Evaluate @var{command}, a string, as a @value{GDBN} CLI command.
|
|
If a GDB exception happens while @var{command} runs, it is
|
|
translated as described in @ref{Exception Handling,,Exception Handling}.
|
|
|
|
@var{from_tty} specifies whether @value{GDBN} ought to consider this
|
|
command as having originated from the user invoking it interactively.
|
|
It must be a boolean value. If omitted, it defaults to @code{False}.
|
|
|
|
By default, any output produced by @var{command} is sent to
|
|
@value{GDBN}'s standard output. If the @var{to_string} parameter is
|
|
@code{True}, then output will be collected by @code{gdb.execute} and
|
|
returned as a string. The default is @code{False}, in which case the
|
|
return value is @code{None}. If @var{to_string} is @code{True}, the
|
|
@value{GDBN} virtual terminal will be temporarily set to unlimited width
|
|
and height, and its pagination will be disabled; @pxref{Screen Size}.
|
|
@end defun
|
|
|
|
@findex gdb.breakpoints
|
|
@defun gdb.breakpoints ()
|
|
Return a sequence holding all of @value{GDBN}'s breakpoints.
|
|
@xref{Breakpoints In Python}, for more information.
|
|
@end defun
|
|
|
|
@findex gdb.parameter
|
|
@defun gdb.parameter (parameter)
|
|
Return the value of a @value{GDBN} parameter. @var{parameter} is a
|
|
string naming the parameter to look up; @var{parameter} may contain
|
|
spaces if the parameter has a multi-part name. For example,
|
|
@samp{print object} is a valid parameter name.
|
|
|
|
If the named parameter does not exist, this function throws a
|
|
@code{gdb.error} (@pxref{Exception Handling}). Otherwise, the
|
|
parameter's value is converted to a Python value of the appropriate
|
|
type, and returned.
|
|
@end defun
|
|
|
|
@findex gdb.history
|
|
@defun gdb.history (number)
|
|
Return a value from @value{GDBN}'s value history (@pxref{Value
|
|
History}). @var{number} indicates which history element to return.
|
|
If @var{number} is negative, then @value{GDBN} will take its absolute value
|
|
and count backward from the last element (i.e., the most recent element) to
|
|
find the value to return. If @var{number} is zero, then @value{GDBN} will
|
|
return the most recent element. If the element specified by @var{number}
|
|
doesn't exist in the value history, a @code{gdb.error} exception will be
|
|
raised.
|
|
|
|
If no exception is raised, the return value is always an instance of
|
|
@code{gdb.Value} (@pxref{Values From Inferior}).
|
|
@end defun
|
|
|
|
@findex gdb.parse_and_eval
|
|
@defun gdb.parse_and_eval (expression)
|
|
Parse @var{expression} as an expression in the current language,
|
|
evaluate it, and return the result as a @code{gdb.Value}.
|
|
@var{expression} must be a string.
|
|
|
|
This function can be useful when implementing a new command
|
|
(@pxref{Commands In Python}), as it provides a way to parse the
|
|
command's argument as an expression. It is also useful simply to
|
|
compute values, for example, it is the only way to get the value of a
|
|
convenience variable (@pxref{Convenience Vars}) as a @code{gdb.Value}.
|
|
@end defun
|
|
|
|
@findex gdb.find_pc_line
|
|
@defun gdb.find_pc_line (pc)
|
|
Return the @code{gdb.Symtab_and_line} object corresponding to the
|
|
@var{pc} value. @xref{Symbol Tables In Python}. If an invalid
|
|
value of @var{pc} is passed as an argument, then the @code{symtab} and
|
|
@code{line} attributes of the returned @code{gdb.Symtab_and_line} object
|
|
will be @code{None} and 0 respectively.
|
|
@end defun
|
|
|
|
@findex gdb.post_event
|
|
@defun gdb.post_event (event)
|
|
Put @var{event}, a callable object taking no arguments, into
|
|
@value{GDBN}'s internal event queue. This callable will be invoked at
|
|
some later point, during @value{GDBN}'s event processing. Events
|
|
posted using @code{post_event} will be run in the order in which they
|
|
were posted; however, there is no way to know when they will be
|
|
processed relative to other events inside @value{GDBN}.
|
|
|
|
@value{GDBN} is not thread-safe. If your Python program uses multiple
|
|
threads, you must be careful to only call @value{GDBN}-specific
|
|
functions in the main @value{GDBN} thread. @code{post_event} ensures
|
|
this. For example:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) python
|
|
>import threading
|
|
>
|
|
>class Writer():
|
|
> def __init__(self, message):
|
|
> self.message = message;
|
|
> def __call__(self):
|
|
> gdb.write(self.message)
|
|
>
|
|
>class MyThread1 (threading.Thread):
|
|
> def run (self):
|
|
> gdb.post_event(Writer("Hello "))
|
|
>
|
|
>class MyThread2 (threading.Thread):
|
|
> def run (self):
|
|
> gdb.post_event(Writer("World\n"))
|
|
>
|
|
>MyThread1().start()
|
|
>MyThread2().start()
|
|
>end
|
|
(@value{GDBP}) Hello World
|
|
@end smallexample
|
|
@end defun
|
|
|
|
@findex gdb.write
|
|
@defun gdb.write (string @r{[}, stream{]})
|
|
Print a string to @value{GDBN}'s paginated output stream. The
|
|
optional @var{stream} determines the stream to print to. The default
|
|
stream is @value{GDBN}'s standard output stream. Possible stream
|
|
values are:
|
|
|
|
@table @code
|
|
@findex STDOUT
|
|
@findex gdb.STDOUT
|
|
@item gdb.STDOUT
|
|
@value{GDBN}'s standard output stream.
|
|
|
|
@findex STDERR
|
|
@findex gdb.STDERR
|
|
@item gdb.STDERR
|
|
@value{GDBN}'s standard error stream.
|
|
|
|
@findex STDLOG
|
|
@findex gdb.STDLOG
|
|
@item gdb.STDLOG
|
|
@value{GDBN}'s log stream (@pxref{Logging Output}).
|
|
@end table
|
|
|
|
Writing to @code{sys.stdout} or @code{sys.stderr} will automatically
|
|
call this function and will automatically direct the output to the
|
|
relevant stream.
|
|
@end defun
|
|
|
|
@findex gdb.flush
|
|
@defun gdb.flush ()
|
|
Flush the buffer of a @value{GDBN} paginated stream so that the
|
|
contents are displayed immediately. @value{GDBN} will flush the
|
|
contents of a stream automatically when it encounters a newline in the
|
|
buffer. The optional @var{stream} determines the stream to flush. The
|
|
default stream is @value{GDBN}'s standard output stream. Possible
|
|
stream values are:
|
|
|
|
@table @code
|
|
@findex STDOUT
|
|
@findex gdb.STDOUT
|
|
@item gdb.STDOUT
|
|
@value{GDBN}'s standard output stream.
|
|
|
|
@findex STDERR
|
|
@findex gdb.STDERR
|
|
@item gdb.STDERR
|
|
@value{GDBN}'s standard error stream.
|
|
|
|
@findex STDLOG
|
|
@findex gdb.STDLOG
|
|
@item gdb.STDLOG
|
|
@value{GDBN}'s log stream (@pxref{Logging Output}).
|
|
|
|
@end table
|
|
|
|
Flushing @code{sys.stdout} or @code{sys.stderr} will automatically
|
|
call this function for the relevant stream.
|
|
@end defun
|
|
|
|
@findex gdb.target_charset
|
|
@defun gdb.target_charset ()
|
|
Return the name of the current target character set (@pxref{Character
|
|
Sets}). This differs from @code{gdb.parameter('target-charset')} in
|
|
that @samp{auto} is never returned.
|
|
@end defun
|
|
|
|
@findex gdb.target_wide_charset
|
|
@defun gdb.target_wide_charset ()
|
|
Return the name of the current target wide character set
|
|
(@pxref{Character Sets}). This differs from
|
|
@code{gdb.parameter('target-wide-charset')} in that @samp{auto} is
|
|
never returned.
|
|
@end defun
|
|
|
|
@findex gdb.solib_name
|
|
@defun gdb.solib_name (address)
|
|
Return the name of the shared library holding the given @var{address}
|
|
as a string, or @code{None}.
|
|
@end defun
|
|
|
|
@findex gdb.decode_line
|
|
@defun gdb.decode_line @r{[}expression@r{]}
|
|
Return locations of the line specified by @var{expression}, or of the
|
|
current line if no argument was given. This function returns a Python
|
|
tuple containing two elements. The first element contains a string
|
|
holding any unparsed section of @var{expression} (or @code{None} if
|
|
the expression has been fully parsed). The second element contains
|
|
either @code{None} or another tuple that contains all the locations
|
|
that match the expression represented as @code{gdb.Symtab_and_line}
|
|
objects (@pxref{Symbol Tables In Python}). If @var{expression} is
|
|
provided, it is decoded the way that @value{GDBN}'s inbuilt
|
|
@code{break} or @code{edit} commands do (@pxref{Specify Location}).
|
|
@end defun
|
|
|
|
@defun gdb.prompt_hook (current_prompt)
|
|
@anchor{prompt_hook}
|
|
|
|
If @var{prompt_hook} is callable, @value{GDBN} will call the method
|
|
assigned to this operation before a prompt is displayed by
|
|
@value{GDBN}.
|
|
|
|
The parameter @code{current_prompt} contains the current @value{GDBN}
|
|
prompt. This method must return a Python string, or @code{None}. If
|
|
a string is returned, the @value{GDBN} prompt will be set to that
|
|
string. If @code{None} is returned, @value{GDBN} will continue to use
|
|
the current prompt.
|
|
|
|
Some prompts cannot be substituted in @value{GDBN}. Secondary prompts
|
|
such as those used by readline for command input, and annotation
|
|
related prompts are prohibited from being changed.
|
|
@end defun
|
|
|
|
@node Exception Handling
|
|
@subsubsection Exception Handling
|
|
@cindex python exceptions
|
|
@cindex exceptions, python
|
|
|
|
When executing the @code{python} command, Python exceptions
|
|
uncaught within the Python code are translated to calls to
|
|
@value{GDBN} error-reporting mechanism. If the command that called
|
|
@code{python} does not handle the error, @value{GDBN} will
|
|
terminate it and print an error message containing the Python
|
|
exception name, the associated value, and the Python call stack
|
|
backtrace at the point where the exception was raised. Example:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) python print foo
|
|
Traceback (most recent call last):
|
|
File "<string>", line 1, in <module>
|
|
NameError: name 'foo' is not defined
|
|
@end smallexample
|
|
|
|
@value{GDBN} errors that happen in @value{GDBN} commands invoked by
|
|
Python code are converted to Python exceptions. The type of the
|
|
Python exception depends on the error.
|
|
|
|
@ftable @code
|
|
@item gdb.error
|
|
This is the base class for most exceptions generated by @value{GDBN}.
|
|
It is derived from @code{RuntimeError}, for compatibility with earlier
|
|
versions of @value{GDBN}.
|
|
|
|
If an error occurring in @value{GDBN} does not fit into some more
|
|
specific category, then the generated exception will have this type.
|
|
|
|
@item gdb.MemoryError
|
|
This is a subclass of @code{gdb.error} which is thrown when an
|
|
operation tried to access invalid memory in the inferior.
|
|
|
|
@item KeyboardInterrupt
|
|
User interrupt (via @kbd{C-c} or by typing @kbd{q} at a pagination
|
|
prompt) is translated to a Python @code{KeyboardInterrupt} exception.
|
|
@end ftable
|
|
|
|
In all cases, your exception handler will see the @value{GDBN} error
|
|
message as its value and the Python call stack backtrace at the Python
|
|
statement closest to where the @value{GDBN} error occured as the
|
|
traceback.
|
|
|
|
@findex gdb.GdbError
|
|
When implementing @value{GDBN} commands in Python via @code{gdb.Command},
|
|
it is useful to be able to throw an exception that doesn't cause a
|
|
traceback to be printed. For example, the user may have invoked the
|
|
command incorrectly. Use the @code{gdb.GdbError} exception
|
|
to handle this case. Example:
|
|
|
|
@smallexample
|
|
(gdb) python
|
|
>class HelloWorld (gdb.Command):
|
|
> """Greet the whole world."""
|
|
> def __init__ (self):
|
|
> super (HelloWorld, self).__init__ ("hello-world", gdb.COMMAND_USER)
|
|
> def invoke (self, args, from_tty):
|
|
> argv = gdb.string_to_argv (args)
|
|
> if len (argv) != 0:
|
|
> raise gdb.GdbError ("hello-world takes no arguments")
|
|
> print "Hello, World!"
|
|
>HelloWorld ()
|
|
>end
|
|
(gdb) hello-world 42
|
|
hello-world takes no arguments
|
|
@end smallexample
|
|
|
|
@node Values From Inferior
|
|
@subsubsection Values From Inferior
|
|
@cindex values from inferior, with Python
|
|
@cindex python, working with values from inferior
|
|
|
|
@cindex @code{gdb.Value}
|
|
@value{GDBN} provides values it obtains from the inferior program in
|
|
an object of type @code{gdb.Value}. @value{GDBN} uses this object
|
|
for its internal bookkeeping of the inferior's values, and for
|
|
fetching values when necessary.
|
|
|
|
Inferior values that are simple scalars can be used directly in
|
|
Python expressions that are valid for the value's data type. Here's
|
|
an example for an integer or floating-point value @code{some_val}:
|
|
|
|
@smallexample
|
|
bar = some_val + 2
|
|
@end smallexample
|
|
|
|
@noindent
|
|
As result of this, @code{bar} will also be a @code{gdb.Value} object
|
|
whose values are of the same type as those of @code{some_val}.
|
|
|
|
Inferior values that are structures or instances of some class can
|
|
be accessed using the Python @dfn{dictionary syntax}. For example, if
|
|
@code{some_val} is a @code{gdb.Value} instance holding a structure, you
|
|
can access its @code{foo} element with:
|
|
|
|
@smallexample
|
|
bar = some_val['foo']
|
|
@end smallexample
|
|
|
|
Again, @code{bar} will also be a @code{gdb.Value} object.
|
|
|
|
A @code{gdb.Value} that represents a function can be executed via
|
|
inferior function call. Any arguments provided to the call must match
|
|
the function's prototype, and must be provided in the order specified
|
|
by that prototype.
|
|
|
|
For example, @code{some_val} is a @code{gdb.Value} instance
|
|
representing a function that takes two integers as arguments. To
|
|
execute this function, call it like so:
|
|
|
|
@smallexample
|
|
result = some_val (10,20)
|
|
@end smallexample
|
|
|
|
Any values returned from a function call will be stored as a
|
|
@code{gdb.Value}.
|
|
|
|
The following attributes are provided:
|
|
|
|
@table @code
|
|
@defvar Value.address
|
|
If this object is addressable, this read-only attribute holds a
|
|
@code{gdb.Value} object representing the address. Otherwise,
|
|
this attribute holds @code{None}.
|
|
@end defvar
|
|
|
|
@cindex optimized out value in Python
|
|
@defvar Value.is_optimized_out
|
|
This read-only boolean attribute is true if the compiler optimized out
|
|
this value, thus it is not available for fetching from the inferior.
|
|
@end defvar
|
|
|
|
@defvar Value.type
|
|
The type of this @code{gdb.Value}. The value of this attribute is a
|
|
@code{gdb.Type} object (@pxref{Types In Python}).
|
|
@end defvar
|
|
|
|
@defvar Value.dynamic_type
|
|
The dynamic type of this @code{gdb.Value}. This uses C@t{++} run-time
|
|
type information (@acronym{RTTI}) to determine the dynamic type of the
|
|
value. If this value is of class type, it will return the class in
|
|
which the value is embedded, if any. If this value is of pointer or
|
|
reference to a class type, it will compute the dynamic type of the
|
|
referenced object, and return a pointer or reference to that type,
|
|
respectively. In all other cases, it will return the value's static
|
|
type.
|
|
|
|
Note that this feature will only work when debugging a C@t{++} program
|
|
that includes @acronym{RTTI} for the object in question. Otherwise,
|
|
it will just return the static type of the value as in @kbd{ptype foo}
|
|
(@pxref{Symbols, ptype}).
|
|
@end defvar
|
|
|
|
@defvar Value.is_lazy
|
|
The value of this read-only boolean attribute is @code{True} if this
|
|
@code{gdb.Value} has not yet been fetched from the inferior.
|
|
@value{GDBN} does not fetch values until necessary, for efficiency.
|
|
For example:
|
|
|
|
@smallexample
|
|
myval = gdb.parse_and_eval ('somevar')
|
|
@end smallexample
|
|
|
|
The value of @code{somevar} is not fetched at this time. It will be
|
|
fetched when the value is needed, or when the @code{fetch_lazy}
|
|
method is invoked.
|
|
@end defvar
|
|
@end table
|
|
|
|
The following methods are provided:
|
|
|
|
@table @code
|
|
@defun Value.__init__ (@var{val})
|
|
Many Python values can be converted directly to a @code{gdb.Value} via
|
|
this object initializer. Specifically:
|
|
|
|
@table @asis
|
|
@item Python boolean
|
|
A Python boolean is converted to the boolean type from the current
|
|
language.
|
|
|
|
@item Python integer
|
|
A Python integer is converted to the C @code{long} type for the
|
|
current architecture.
|
|
|
|
@item Python long
|
|
A Python long is converted to the C @code{long long} type for the
|
|
current architecture.
|
|
|
|
@item Python float
|
|
A Python float is converted to the C @code{double} type for the
|
|
current architecture.
|
|
|
|
@item Python string
|
|
A Python string is converted to a target string, using the current
|
|
target encoding.
|
|
|
|
@item @code{gdb.Value}
|
|
If @code{val} is a @code{gdb.Value}, then a copy of the value is made.
|
|
|
|
@item @code{gdb.LazyString}
|
|
If @code{val} is a @code{gdb.LazyString} (@pxref{Lazy Strings In
|
|
Python}), then the lazy string's @code{value} method is called, and
|
|
its result is used.
|
|
@end table
|
|
@end defun
|
|
|
|
@defun Value.cast (type)
|
|
Return a new instance of @code{gdb.Value} that is the result of
|
|
casting this instance to the type described by @var{type}, which must
|
|
be a @code{gdb.Type} object. If the cast cannot be performed for some
|
|
reason, this method throws an exception.
|
|
@end defun
|
|
|
|
@defun Value.dereference ()
|
|
For pointer data types, this method returns a new @code{gdb.Value} object
|
|
whose contents is the object pointed to by the pointer. For example, if
|
|
@code{foo} is a C pointer to an @code{int}, declared in your C program as
|
|
|
|
@smallexample
|
|
int *foo;
|
|
@end smallexample
|
|
|
|
@noindent
|
|
then you can use the corresponding @code{gdb.Value} to access what
|
|
@code{foo} points to like this:
|
|
|
|
@smallexample
|
|
bar = foo.dereference ()
|
|
@end smallexample
|
|
|
|
The result @code{bar} will be a @code{gdb.Value} object holding the
|
|
value pointed to by @code{foo}.
|
|
|
|
A similar function @code{Value.referenced_value} exists which also
|
|
returns @code{gdb.Value} objects corresonding to the values pointed to
|
|
by pointer values (and additionally, values referenced by reference
|
|
values). However, the behavior of @code{Value.dereference}
|
|
differs from @code{Value.referenced_value} by the fact that the
|
|
behavior of @code{Value.dereference} is identical to applying the C
|
|
unary operator @code{*} on a given value. For example, consider a
|
|
reference to a pointer @code{ptrref}, declared in your C@t{++} program
|
|
as
|
|
|
|
@smallexample
|
|
typedef int *intptr;
|
|
...
|
|
int val = 10;
|
|
intptr ptr = &val;
|
|
intptr &ptrref = ptr;
|
|
@end smallexample
|
|
|
|
Though @code{ptrref} is a reference value, one can apply the method
|
|
@code{Value.dereference} to the @code{gdb.Value} object corresponding
|
|
to it and obtain a @code{gdb.Value} which is identical to that
|
|
corresponding to @code{val}. However, if you apply the method
|
|
@code{Value.referenced_value}, the result would be a @code{gdb.Value}
|
|
object identical to that corresponding to @code{ptr}.
|
|
|
|
@smallexample
|
|
py_ptrref = gdb.parse_and_eval ("ptrref")
|
|
py_val = py_ptrref.dereference ()
|
|
py_ptr = py_ptrref.referenced_value ()
|
|
@end smallexample
|
|
|
|
The @code{gdb.Value} object @code{py_val} is identical to that
|
|
corresponding to @code{val}, and @code{py_ptr} is identical to that
|
|
corresponding to @code{ptr}. In general, @code{Value.dereference} can
|
|
be applied whenever the C unary operator @code{*} can be applied
|
|
to the corresponding C value. For those cases where applying both
|
|
@code{Value.dereference} and @code{Value.referenced_value} is allowed,
|
|
the results obtained need not be identical (as we have seen in the above
|
|
example). The results are however identical when applied on
|
|
@code{gdb.Value} objects corresponding to pointers (@code{gdb.Value}
|
|
objects with type code @code{TYPE_CODE_PTR}) in a C/C@t{++} program.
|
|
@end defun
|
|
|
|
@defun Value.referenced_value ()
|
|
For pointer or reference data types, this method returns a new
|
|
@code{gdb.Value} object corresponding to the value referenced by the
|
|
pointer/reference value. For pointer data types,
|
|
@code{Value.dereference} and @code{Value.referenced_value} produce
|
|
identical results. The difference between these methods is that
|
|
@code{Value.dereference} cannot get the values referenced by reference
|
|
values. For example, consider a reference to an @code{int}, declared
|
|
in your C@t{++} program as
|
|
|
|
@smallexample
|
|
int val = 10;
|
|
int &ref = val;
|
|
@end smallexample
|
|
|
|
@noindent
|
|
then applying @code{Value.dereference} to the @code{gdb.Value} object
|
|
corresponding to @code{ref} will result in an error, while applying
|
|
@code{Value.referenced_value} will result in a @code{gdb.Value} object
|
|
identical to that corresponding to @code{val}.
|
|
|
|
@smallexample
|
|
py_ref = gdb.parse_and_eval ("ref")
|
|
er_ref = py_ref.dereference () # Results in error
|
|
py_val = py_ref.referenced_value () # Returns the referenced value
|
|
@end smallexample
|
|
|
|
The @code{gdb.Value} object @code{py_val} is identical to that
|
|
corresponding to @code{val}.
|
|
@end defun
|
|
|
|
@defun Value.dynamic_cast (type)
|
|
Like @code{Value.cast}, but works as if the C@t{++} @code{dynamic_cast}
|
|
operator were used. Consult a C@t{++} reference for details.
|
|
@end defun
|
|
|
|
@defun Value.reinterpret_cast (type)
|
|
Like @code{Value.cast}, but works as if the C@t{++} @code{reinterpret_cast}
|
|
operator were used. Consult a C@t{++} reference for details.
|
|
@end defun
|
|
|
|
@defun Value.string (@r{[}encoding@r{[}, errors@r{[}, length@r{]]]})
|
|
If this @code{gdb.Value} represents a string, then this method
|
|
converts the contents to a Python string. Otherwise, this method will
|
|
throw an exception.
|
|
|
|
Strings are recognized in a language-specific way; whether a given
|
|
@code{gdb.Value} represents a string is determined by the current
|
|
language.
|
|
|
|
For C-like languages, a value is a string if it is a pointer to or an
|
|
array of characters or ints. The string is assumed to be terminated
|
|
by a zero of the appropriate width. However if the optional length
|
|
argument is given, the string will be converted to that given length,
|
|
ignoring any embedded zeros that the string may contain.
|
|
|
|
If the optional @var{encoding} argument is given, it must be a string
|
|
naming the encoding of the string in the @code{gdb.Value}, such as
|
|
@code{"ascii"}, @code{"iso-8859-6"} or @code{"utf-8"}. It accepts
|
|
the same encodings as the corresponding argument to Python's
|
|
@code{string.decode} method, and the Python codec machinery will be used
|
|
to convert the string. If @var{encoding} is not given, or if
|
|
@var{encoding} is the empty string, then either the @code{target-charset}
|
|
(@pxref{Character Sets}) will be used, or a language-specific encoding
|
|
will be used, if the current language is able to supply one.
|
|
|
|
The optional @var{errors} argument is the same as the corresponding
|
|
argument to Python's @code{string.decode} method.
|
|
|
|
If the optional @var{length} argument is given, the string will be
|
|
fetched and converted to the given length.
|
|
@end defun
|
|
|
|
@defun Value.lazy_string (@r{[}encoding @r{[}, length@r{]]})
|
|
If this @code{gdb.Value} represents a string, then this method
|
|
converts the contents to a @code{gdb.LazyString} (@pxref{Lazy Strings
|
|
In Python}). Otherwise, this method will throw an exception.
|
|
|
|
If the optional @var{encoding} argument is given, it must be a string
|
|
naming the encoding of the @code{gdb.LazyString}. Some examples are:
|
|
@samp{ascii}, @samp{iso-8859-6} or @samp{utf-8}. If the
|
|
@var{encoding} argument is an encoding that @value{GDBN} does
|
|
recognize, @value{GDBN} will raise an error.
|
|
|
|
When a lazy string is printed, the @value{GDBN} encoding machinery is
|
|
used to convert the string during printing. If the optional
|
|
@var{encoding} argument is not provided, or is an empty string,
|
|
@value{GDBN} will automatically select the encoding most suitable for
|
|
the string type. For further information on encoding in @value{GDBN}
|
|
please see @ref{Character Sets}.
|
|
|
|
If the optional @var{length} argument is given, the string will be
|
|
fetched and encoded to the length of characters specified. If
|
|
the @var{length} argument is not provided, the string will be fetched
|
|
and encoded until a null of appropriate width is found.
|
|
@end defun
|
|
|
|
@defun Value.fetch_lazy ()
|
|
If the @code{gdb.Value} object is currently a lazy value
|
|
(@code{gdb.Value.is_lazy} is @code{True}), then the value is
|
|
fetched from the inferior. Any errors that occur in the process
|
|
will produce a Python exception.
|
|
|
|
If the @code{gdb.Value} object is not a lazy value, this method
|
|
has no effect.
|
|
|
|
This method does not return a value.
|
|
@end defun
|
|
|
|
@end table
|
|
|
|
@node Types In Python
|
|
@subsubsection Types In Python
|
|
@cindex types in Python
|
|
@cindex Python, working with types
|
|
|
|
@tindex gdb.Type
|
|
@value{GDBN} represents types from the inferior using the class
|
|
@code{gdb.Type}.
|
|
|
|
The following type-related functions are available in the @code{gdb}
|
|
module:
|
|
|
|
@findex gdb.lookup_type
|
|
@defun gdb.lookup_type (name @r{[}, block@r{]})
|
|
This function looks up a type by name. @var{name} is the name of the
|
|
type to look up. It must be a string.
|
|
|
|
If @var{block} is given, then @var{name} is looked up in that scope.
|
|
Otherwise, it is searched for globally.
|
|
|
|
Ordinarily, this function will return an instance of @code{gdb.Type}.
|
|
If the named type cannot be found, it will throw an exception.
|
|
@end defun
|
|
|
|
If the type is a structure or class type, or an enum type, the fields
|
|
of that type can be accessed using the Python @dfn{dictionary syntax}.
|
|
For example, if @code{some_type} is a @code{gdb.Type} instance holding
|
|
a structure type, you can access its @code{foo} field with:
|
|
|
|
@smallexample
|
|
bar = some_type['foo']
|
|
@end smallexample
|
|
|
|
@code{bar} will be a @code{gdb.Field} object; see below under the
|
|
description of the @code{Type.fields} method for a description of the
|
|
@code{gdb.Field} class.
|
|
|
|
An instance of @code{Type} has the following attributes:
|
|
|
|
@table @code
|
|
@defvar Type.code
|
|
The type code for this type. The type code will be one of the
|
|
@code{TYPE_CODE_} constants defined below.
|
|
@end defvar
|
|
|
|
@defvar Type.sizeof
|
|
The size of this type, in target @code{char} units. Usually, a
|
|
target's @code{char} type will be an 8-bit byte. However, on some
|
|
unusual platforms, this type may have a different size.
|
|
@end defvar
|
|
|
|
@defvar Type.tag
|
|
The tag name for this type. The tag name is the name after
|
|
@code{struct}, @code{union}, or @code{enum} in C and C@t{++}; not all
|
|
languages have this concept. If this type has no tag name, then
|
|
@code{None} is returned.
|
|
@end defvar
|
|
@end table
|
|
|
|
The following methods are provided:
|
|
|
|
@table @code
|
|
@defun Type.fields ()
|
|
For structure and union types, this method returns the fields. Range
|
|
types have two fields, the minimum and maximum values. Enum types
|
|
have one field per enum constant. Function and method types have one
|
|
field per parameter. The base types of C@t{++} classes are also
|
|
represented as fields. If the type has no fields, or does not fit
|
|
into one of these categories, an empty sequence will be returned.
|
|
|
|
Each field is a @code{gdb.Field} object, with some pre-defined attributes:
|
|
@table @code
|
|
@item bitpos
|
|
This attribute is not available for @code{static} fields (as in
|
|
C@t{++} or Java). For non-@code{static} fields, the value is the bit
|
|
position of the field. For @code{enum} fields, the value is the
|
|
enumeration member's integer representation.
|
|
|
|
@item name
|
|
The name of the field, or @code{None} for anonymous fields.
|
|
|
|
@item artificial
|
|
This is @code{True} if the field is artificial, usually meaning that
|
|
it was provided by the compiler and not the user. This attribute is
|
|
always provided, and is @code{False} if the field is not artificial.
|
|
|
|
@item is_base_class
|
|
This is @code{True} if the field represents a base class of a C@t{++}
|
|
structure. This attribute is always provided, and is @code{False}
|
|
if the field is not a base class of the type that is the argument of
|
|
@code{fields}, or if that type was not a C@t{++} class.
|
|
|
|
@item bitsize
|
|
If the field is packed, or is a bitfield, then this will have a
|
|
non-zero value, which is the size of the field in bits. Otherwise,
|
|
this will be zero; in this case the field's size is given by its type.
|
|
|
|
@item type
|
|
The type of the field. This is usually an instance of @code{Type},
|
|
but it can be @code{None} in some situations.
|
|
@end table
|
|
@end defun
|
|
|
|
@defun Type.array (@var{n1} @r{[}, @var{n2}@r{]})
|
|
Return a new @code{gdb.Type} object which represents an array of this
|
|
type. If one argument is given, it is the inclusive upper bound of
|
|
the array; in this case the lower bound is zero. If two arguments are
|
|
given, the first argument is the lower bound of the array, and the
|
|
second argument is the upper bound of the array. An array's length
|
|
must not be negative, but the bounds can be.
|
|
@end defun
|
|
|
|
@defun Type.const ()
|
|
Return a new @code{gdb.Type} object which represents a
|
|
@code{const}-qualified variant of this type.
|
|
@end defun
|
|
|
|
@defun Type.volatile ()
|
|
Return a new @code{gdb.Type} object which represents a
|
|
@code{volatile}-qualified variant of this type.
|
|
@end defun
|
|
|
|
@defun Type.unqualified ()
|
|
Return a new @code{gdb.Type} object which represents an unqualified
|
|
variant of this type. That is, the result is neither @code{const} nor
|
|
@code{volatile}.
|
|
@end defun
|
|
|
|
@defun Type.range ()
|
|
Return a Python @code{Tuple} object that contains two elements: the
|
|
low bound of the argument type and the high bound of that type. If
|
|
the type does not have a range, @value{GDBN} will raise a
|
|
@code{gdb.error} exception (@pxref{Exception Handling}).
|
|
@end defun
|
|
|
|
@defun Type.reference ()
|
|
Return a new @code{gdb.Type} object which represents a reference to this
|
|
type.
|
|
@end defun
|
|
|
|
@defun Type.pointer ()
|
|
Return a new @code{gdb.Type} object which represents a pointer to this
|
|
type.
|
|
@end defun
|
|
|
|
@defun Type.strip_typedefs ()
|
|
Return a new @code{gdb.Type} that represents the real type,
|
|
after removing all layers of typedefs.
|
|
@end defun
|
|
|
|
@defun Type.target ()
|
|
Return a new @code{gdb.Type} object which represents the target type
|
|
of this type.
|
|
|
|
For a pointer type, the target type is the type of the pointed-to
|
|
object. For an array type (meaning C-like arrays), the target type is
|
|
the type of the elements of the array. For a function or method type,
|
|
the target type is the type of the return value. For a complex type,
|
|
the target type is the type of the elements. For a typedef, the
|
|
target type is the aliased type.
|
|
|
|
If the type does not have a target, this method will throw an
|
|
exception.
|
|
@end defun
|
|
|
|
@defun Type.template_argument (n @r{[}, block@r{]})
|
|
If this @code{gdb.Type} is an instantiation of a template, this will
|
|
return a new @code{gdb.Type} which represents the type of the
|
|
@var{n}th template argument.
|
|
|
|
If this @code{gdb.Type} is not a template type, this will throw an
|
|
exception. Ordinarily, only C@t{++} code will have template types.
|
|
|
|
If @var{block} is given, then @var{name} is looked up in that scope.
|
|
Otherwise, it is searched for globally.
|
|
@end defun
|
|
@end table
|
|
|
|
|
|
Each type has a code, which indicates what category this type falls
|
|
into. The available type categories are represented by constants
|
|
defined in the @code{gdb} module:
|
|
|
|
@table @code
|
|
@findex TYPE_CODE_PTR
|
|
@findex gdb.TYPE_CODE_PTR
|
|
@item gdb.TYPE_CODE_PTR
|
|
The type is a pointer.
|
|
|
|
@findex TYPE_CODE_ARRAY
|
|
@findex gdb.TYPE_CODE_ARRAY
|
|
@item gdb.TYPE_CODE_ARRAY
|
|
The type is an array.
|
|
|
|
@findex TYPE_CODE_STRUCT
|
|
@findex gdb.TYPE_CODE_STRUCT
|
|
@item gdb.TYPE_CODE_STRUCT
|
|
The type is a structure.
|
|
|
|
@findex TYPE_CODE_UNION
|
|
@findex gdb.TYPE_CODE_UNION
|
|
@item gdb.TYPE_CODE_UNION
|
|
The type is a union.
|
|
|
|
@findex TYPE_CODE_ENUM
|
|
@findex gdb.TYPE_CODE_ENUM
|
|
@item gdb.TYPE_CODE_ENUM
|
|
The type is an enum.
|
|
|
|
@findex TYPE_CODE_FLAGS
|
|
@findex gdb.TYPE_CODE_FLAGS
|
|
@item gdb.TYPE_CODE_FLAGS
|
|
A bit flags type, used for things such as status registers.
|
|
|
|
@findex TYPE_CODE_FUNC
|
|
@findex gdb.TYPE_CODE_FUNC
|
|
@item gdb.TYPE_CODE_FUNC
|
|
The type is a function.
|
|
|
|
@findex TYPE_CODE_INT
|
|
@findex gdb.TYPE_CODE_INT
|
|
@item gdb.TYPE_CODE_INT
|
|
The type is an integer type.
|
|
|
|
@findex TYPE_CODE_FLT
|
|
@findex gdb.TYPE_CODE_FLT
|
|
@item gdb.TYPE_CODE_FLT
|
|
A floating point type.
|
|
|
|
@findex TYPE_CODE_VOID
|
|
@findex gdb.TYPE_CODE_VOID
|
|
@item gdb.TYPE_CODE_VOID
|
|
The special type @code{void}.
|
|
|
|
@findex TYPE_CODE_SET
|
|
@findex gdb.TYPE_CODE_SET
|
|
@item gdb.TYPE_CODE_SET
|
|
A Pascal set type.
|
|
|
|
@findex TYPE_CODE_RANGE
|
|
@findex gdb.TYPE_CODE_RANGE
|
|
@item gdb.TYPE_CODE_RANGE
|
|
A range type, that is, an integer type with bounds.
|
|
|
|
@findex TYPE_CODE_STRING
|
|
@findex gdb.TYPE_CODE_STRING
|
|
@item gdb.TYPE_CODE_STRING
|
|
A string type. Note that this is only used for certain languages with
|
|
language-defined string types; C strings are not represented this way.
|
|
|
|
@findex TYPE_CODE_BITSTRING
|
|
@findex gdb.TYPE_CODE_BITSTRING
|
|
@item gdb.TYPE_CODE_BITSTRING
|
|
A string of bits.
|
|
|
|
@findex TYPE_CODE_ERROR
|
|
@findex gdb.TYPE_CODE_ERROR
|
|
@item gdb.TYPE_CODE_ERROR
|
|
An unknown or erroneous type.
|
|
|
|
@findex TYPE_CODE_METHOD
|
|
@findex gdb.TYPE_CODE_METHOD
|
|
@item gdb.TYPE_CODE_METHOD
|
|
A method type, as found in C@t{++} or Java.
|
|
|
|
@findex TYPE_CODE_METHODPTR
|
|
@findex gdb.TYPE_CODE_METHODPTR
|
|
@item gdb.TYPE_CODE_METHODPTR
|
|
A pointer-to-member-function.
|
|
|
|
@findex TYPE_CODE_MEMBERPTR
|
|
@findex gdb.TYPE_CODE_MEMBERPTR
|
|
@item gdb.TYPE_CODE_MEMBERPTR
|
|
A pointer-to-member.
|
|
|
|
@findex TYPE_CODE_REF
|
|
@findex gdb.TYPE_CODE_REF
|
|
@item gdb.TYPE_CODE_REF
|
|
A reference type.
|
|
|
|
@findex TYPE_CODE_CHAR
|
|
@findex gdb.TYPE_CODE_CHAR
|
|
@item gdb.TYPE_CODE_CHAR
|
|
A character type.
|
|
|
|
@findex TYPE_CODE_BOOL
|
|
@findex gdb.TYPE_CODE_BOOL
|
|
@item gdb.TYPE_CODE_BOOL
|
|
A boolean type.
|
|
|
|
@findex TYPE_CODE_COMPLEX
|
|
@findex gdb.TYPE_CODE_COMPLEX
|
|
@item gdb.TYPE_CODE_COMPLEX
|
|
A complex float type.
|
|
|
|
@findex TYPE_CODE_TYPEDEF
|
|
@findex gdb.TYPE_CODE_TYPEDEF
|
|
@item gdb.TYPE_CODE_TYPEDEF
|
|
A typedef to some other type.
|
|
|
|
@findex TYPE_CODE_NAMESPACE
|
|
@findex gdb.TYPE_CODE_NAMESPACE
|
|
@item gdb.TYPE_CODE_NAMESPACE
|
|
A C@t{++} namespace.
|
|
|
|
@findex TYPE_CODE_DECFLOAT
|
|
@findex gdb.TYPE_CODE_DECFLOAT
|
|
@item gdb.TYPE_CODE_DECFLOAT
|
|
A decimal floating point type.
|
|
|
|
@findex TYPE_CODE_INTERNAL_FUNCTION
|
|
@findex gdb.TYPE_CODE_INTERNAL_FUNCTION
|
|
@item gdb.TYPE_CODE_INTERNAL_FUNCTION
|
|
A function internal to @value{GDBN}. This is the type used to represent
|
|
convenience functions.
|
|
@end table
|
|
|
|
Further support for types is provided in the @code{gdb.types}
|
|
Python module (@pxref{gdb.types}).
|
|
|
|
@node Pretty Printing API
|
|
@subsubsection Pretty Printing API
|
|
|
|
An example output is provided (@pxref{Pretty Printing}).
|
|
|
|
A pretty-printer is just an object that holds a value and implements a
|
|
specific interface, defined here.
|
|
|
|
@defun pretty_printer.children (self)
|
|
@value{GDBN} will call this method on a pretty-printer to compute the
|
|
children of the pretty-printer's value.
|
|
|
|
This method must return an object conforming to the Python iterator
|
|
protocol. Each item returned by the iterator must be a tuple holding
|
|
two elements. The first element is the ``name'' of the child; the
|
|
second element is the child's value. The value can be any Python
|
|
object which is convertible to a @value{GDBN} value.
|
|
|
|
This method is optional. If it does not exist, @value{GDBN} will act
|
|
as though the value has no children.
|
|
@end defun
|
|
|
|
@defun pretty_printer.display_hint (self)
|
|
The CLI may call this method and use its result to change the
|
|
formatting of a value. The result will also be supplied to an MI
|
|
consumer as a @samp{displayhint} attribute of the variable being
|
|
printed.
|
|
|
|
This method is optional. If it does exist, this method must return a
|
|
string.
|
|
|
|
Some display hints are predefined by @value{GDBN}:
|
|
|
|
@table @samp
|
|
@item array
|
|
Indicate that the object being printed is ``array-like''. The CLI
|
|
uses this to respect parameters such as @code{set print elements} and
|
|
@code{set print array}.
|
|
|
|
@item map
|
|
Indicate that the object being printed is ``map-like'', and that the
|
|
children of this value can be assumed to alternate between keys and
|
|
values.
|
|
|
|
@item string
|
|
Indicate that the object being printed is ``string-like''. If the
|
|
printer's @code{to_string} method returns a Python string of some
|
|
kind, then @value{GDBN} will call its internal language-specific
|
|
string-printing function to format the string. For the CLI this means
|
|
adding quotation marks, possibly escaping some characters, respecting
|
|
@code{set print elements}, and the like.
|
|
@end table
|
|
@end defun
|
|
|
|
@defun pretty_printer.to_string (self)
|
|
@value{GDBN} will call this method to display the string
|
|
representation of the value passed to the object's constructor.
|
|
|
|
When printing from the CLI, if the @code{to_string} method exists,
|
|
then @value{GDBN} will prepend its result to the values returned by
|
|
@code{children}. Exactly how this formatting is done is dependent on
|
|
the display hint, and may change as more hints are added. Also,
|
|
depending on the print settings (@pxref{Print Settings}), the CLI may
|
|
print just the result of @code{to_string} in a stack trace, omitting
|
|
the result of @code{children}.
|
|
|
|
If this method returns a string, it is printed verbatim.
|
|
|
|
Otherwise, if this method returns an instance of @code{gdb.Value},
|
|
then @value{GDBN} prints this value. This may result in a call to
|
|
another pretty-printer.
|
|
|
|
If instead the method returns a Python value which is convertible to a
|
|
@code{gdb.Value}, then @value{GDBN} performs the conversion and prints
|
|
the resulting value. Again, this may result in a call to another
|
|
pretty-printer. Python scalars (integers, floats, and booleans) and
|
|
strings are convertible to @code{gdb.Value}; other types are not.
|
|
|
|
Finally, if this method returns @code{None} then no further operations
|
|
are peformed in this method and nothing is printed.
|
|
|
|
If the result is not one of these types, an exception is raised.
|
|
@end defun
|
|
|
|
@value{GDBN} provides a function which can be used to look up the
|
|
default pretty-printer for a @code{gdb.Value}:
|
|
|
|
@findex gdb.default_visualizer
|
|
@defun gdb.default_visualizer (value)
|
|
This function takes a @code{gdb.Value} object as an argument. If a
|
|
pretty-printer for this value exists, then it is returned. If no such
|
|
printer exists, then this returns @code{None}.
|
|
@end defun
|
|
|
|
@node Selecting Pretty-Printers
|
|
@subsubsection Selecting Pretty-Printers
|
|
|
|
The Python list @code{gdb.pretty_printers} contains an array of
|
|
functions or callable objects that have been registered via addition
|
|
as a pretty-printer. Printers in this list are called @code{global}
|
|
printers, they're available when debugging all inferiors.
|
|
Each @code{gdb.Progspace} contains a @code{pretty_printers} attribute.
|
|
Each @code{gdb.Objfile} also contains a @code{pretty_printers}
|
|
attribute.
|
|
|
|
Each function on these lists is passed a single @code{gdb.Value}
|
|
argument and should return a pretty-printer object conforming to the
|
|
interface definition above (@pxref{Pretty Printing API}). If a function
|
|
cannot create a pretty-printer for the value, it should return
|
|
@code{None}.
|
|
|
|
@value{GDBN} first checks the @code{pretty_printers} attribute of each
|
|
@code{gdb.Objfile} in the current program space and iteratively calls
|
|
each enabled lookup routine in the list for that @code{gdb.Objfile}
|
|
until it receives a pretty-printer object.
|
|
If no pretty-printer is found in the objfile lists, @value{GDBN} then
|
|
searches the pretty-printer list of the current program space,
|
|
calling each enabled function until an object is returned.
|
|
After these lists have been exhausted, it tries the global
|
|
@code{gdb.pretty_printers} list, again calling each enabled function until an
|
|
object is returned.
|
|
|
|
The order in which the objfiles are searched is not specified. For a
|
|
given list, functions are always invoked from the head of the list,
|
|
and iterated over sequentially until the end of the list, or a printer
|
|
object is returned.
|
|
|
|
For various reasons a pretty-printer may not work.
|
|
For example, the underlying data structure may have changed and
|
|
the pretty-printer is out of date.
|
|
|
|
The consequences of a broken pretty-printer are severe enough that
|
|
@value{GDBN} provides support for enabling and disabling individual
|
|
printers. For example, if @code{print frame-arguments} is on,
|
|
a backtrace can become highly illegible if any argument is printed
|
|
with a broken printer.
|
|
|
|
Pretty-printers are enabled and disabled by attaching an @code{enabled}
|
|
attribute to the registered function or callable object. If this attribute
|
|
is present and its value is @code{False}, the printer is disabled, otherwise
|
|
the printer is enabled.
|
|
|
|
@node Writing a Pretty-Printer
|
|
@subsubsection Writing a Pretty-Printer
|
|
@cindex writing a pretty-printer
|
|
|
|
A pretty-printer consists of two parts: a lookup function to detect
|
|
if the type is supported, and the printer itself.
|
|
|
|
Here is an example showing how a @code{std::string} printer might be
|
|
written. @xref{Pretty Printing API}, for details on the API this class
|
|
must provide.
|
|
|
|
@smallexample
|
|
class StdStringPrinter(object):
|
|
"Print a std::string"
|
|
|
|
def __init__(self, val):
|
|
self.val = val
|
|
|
|
def to_string(self):
|
|
return self.val['_M_dataplus']['_M_p']
|
|
|
|
def display_hint(self):
|
|
return 'string'
|
|
@end smallexample
|
|
|
|
And here is an example showing how a lookup function for the printer
|
|
example above might be written.
|
|
|
|
@smallexample
|
|
def str_lookup_function(val):
|
|
lookup_tag = val.type.tag
|
|
if lookup_tag == None:
|
|
return None
|
|
regex = re.compile("^std::basic_string<char,.*>$")
|
|
if regex.match(lookup_tag):
|
|
return StdStringPrinter(val)
|
|
return None
|
|
@end smallexample
|
|
|
|
The example lookup function extracts the value's type, and attempts to
|
|
match it to a type that it can pretty-print. If it is a type the
|
|
printer can pretty-print, it will return a printer object. If not, it
|
|
returns @code{None}.
|
|
|
|
We recommend that you put your core pretty-printers into a Python
|
|
package. If your pretty-printers are for use with a library, we
|
|
further recommend embedding a version number into the package name.
|
|
This practice will enable @value{GDBN} to load multiple versions of
|
|
your pretty-printers at the same time, because they will have
|
|
different names.
|
|
|
|
You should write auto-loaded code (@pxref{Python Auto-loading}) such that it
|
|
can be evaluated multiple times without changing its meaning. An
|
|
ideal auto-load file will consist solely of @code{import}s of your
|
|
printer modules, followed by a call to a register pretty-printers with
|
|
the current objfile.
|
|
|
|
Taken as a whole, this approach will scale nicely to multiple
|
|
inferiors, each potentially using a different library version.
|
|
Embedding a version number in the Python package name will ensure that
|
|
@value{GDBN} is able to load both sets of printers simultaneously.
|
|
Then, because the search for pretty-printers is done by objfile, and
|
|
because your auto-loaded code took care to register your library's
|
|
printers with a specific objfile, @value{GDBN} will find the correct
|
|
printers for the specific version of the library used by each
|
|
inferior.
|
|
|
|
To continue the @code{std::string} example (@pxref{Pretty Printing API}),
|
|
this code might appear in @code{gdb.libstdcxx.v6}:
|
|
|
|
@smallexample
|
|
def register_printers(objfile):
|
|
objfile.pretty_printers.append(str_lookup_function)
|
|
@end smallexample
|
|
|
|
@noindent
|
|
And then the corresponding contents of the auto-load file would be:
|
|
|
|
@smallexample
|
|
import gdb.libstdcxx.v6
|
|
gdb.libstdcxx.v6.register_printers(gdb.current_objfile())
|
|
@end smallexample
|
|
|
|
The previous example illustrates a basic pretty-printer.
|
|
There are a few things that can be improved on.
|
|
The printer doesn't have a name, making it hard to identify in a
|
|
list of installed printers. The lookup function has a name, but
|
|
lookup functions can have arbitrary, even identical, names.
|
|
|
|
Second, the printer only handles one type, whereas a library typically has
|
|
several types. One could install a lookup function for each desired type
|
|
in the library, but one could also have a single lookup function recognize
|
|
several types. The latter is the conventional way this is handled.
|
|
If a pretty-printer can handle multiple data types, then its
|
|
@dfn{subprinters} are the printers for the individual data types.
|
|
|
|
The @code{gdb.printing} module provides a formal way of solving these
|
|
problems (@pxref{gdb.printing}).
|
|
Here is another example that handles multiple types.
|
|
|
|
These are the types we are going to pretty-print:
|
|
|
|
@smallexample
|
|
struct foo @{ int a, b; @};
|
|
struct bar @{ struct foo x, y; @};
|
|
@end smallexample
|
|
|
|
Here are the printers:
|
|
|
|
@smallexample
|
|
class fooPrinter:
|
|
"""Print a foo object."""
|
|
|
|
def __init__(self, val):
|
|
self.val = val
|
|
|
|
def to_string(self):
|
|
return ("a=<" + str(self.val["a"]) +
|
|
"> b=<" + str(self.val["b"]) + ">")
|
|
|
|
class barPrinter:
|
|
"""Print a bar object."""
|
|
|
|
def __init__(self, val):
|
|
self.val = val
|
|
|
|
def to_string(self):
|
|
return ("x=<" + str(self.val["x"]) +
|
|
"> y=<" + str(self.val["y"]) + ">")
|
|
@end smallexample
|
|
|
|
This example doesn't need a lookup function, that is handled by the
|
|
@code{gdb.printing} module. Instead a function is provided to build up
|
|
the object that handles the lookup.
|
|
|
|
@smallexample
|
|
import gdb.printing
|
|
|
|
def build_pretty_printer():
|
|
pp = gdb.printing.RegexpCollectionPrettyPrinter(
|
|
"my_library")
|
|
pp.add_printer('foo', '^foo$', fooPrinter)
|
|
pp.add_printer('bar', '^bar$', barPrinter)
|
|
return pp
|
|
@end smallexample
|
|
|
|
And here is the autoload support:
|
|
|
|
@smallexample
|
|
import gdb.printing
|
|
import my_library
|
|
gdb.printing.register_pretty_printer(
|
|
gdb.current_objfile(),
|
|
my_library.build_pretty_printer())
|
|
@end smallexample
|
|
|
|
Finally, when this printer is loaded into @value{GDBN}, here is the
|
|
corresponding output of @samp{info pretty-printer}:
|
|
|
|
@smallexample
|
|
(gdb) info pretty-printer
|
|
my_library.so:
|
|
my_library
|
|
foo
|
|
bar
|
|
@end smallexample
|
|
|
|
@node Inferiors In Python
|
|
@subsubsection Inferiors In Python
|
|
@cindex inferiors in Python
|
|
|
|
@findex gdb.Inferior
|
|
Programs which are being run under @value{GDBN} are called inferiors
|
|
(@pxref{Inferiors and Programs}). Python scripts can access
|
|
information about and manipulate inferiors controlled by @value{GDBN}
|
|
via objects of the @code{gdb.Inferior} class.
|
|
|
|
The following inferior-related functions are available in the @code{gdb}
|
|
module:
|
|
|
|
@defun gdb.inferiors ()
|
|
Return a tuple containing all inferior objects.
|
|
@end defun
|
|
|
|
@defun gdb.selected_inferior ()
|
|
Return an object representing the current inferior.
|
|
@end defun
|
|
|
|
A @code{gdb.Inferior} object has the following attributes:
|
|
|
|
@table @code
|
|
@defvar Inferior.num
|
|
ID of inferior, as assigned by GDB.
|
|
@end defvar
|
|
|
|
@defvar Inferior.pid
|
|
Process ID of the inferior, as assigned by the underlying operating
|
|
system.
|
|
@end defvar
|
|
|
|
@defvar Inferior.was_attached
|
|
Boolean signaling whether the inferior was created using `attach', or
|
|
started by @value{GDBN} itself.
|
|
@end defvar
|
|
@end table
|
|
|
|
A @code{gdb.Inferior} object has the following methods:
|
|
|
|
@table @code
|
|
@defun Inferior.is_valid ()
|
|
Returns @code{True} if the @code{gdb.Inferior} object is valid,
|
|
@code{False} if not. A @code{gdb.Inferior} object will become invalid
|
|
if the inferior no longer exists within @value{GDBN}. All other
|
|
@code{gdb.Inferior} methods will throw an exception if it is invalid
|
|
at the time the method is called.
|
|
@end defun
|
|
|
|
@defun Inferior.threads ()
|
|
This method returns a tuple holding all the threads which are valid
|
|
when it is called. If there are no valid threads, the method will
|
|
return an empty tuple.
|
|
@end defun
|
|
|
|
@findex Inferior.read_memory
|
|
@defun Inferior.read_memory (address, length)
|
|
Read @var{length} bytes of memory from the inferior, starting at
|
|
@var{address}. Returns a buffer object, which behaves much like an array
|
|
or a string. It can be modified and given to the
|
|
@code{Inferior.write_memory} function.
|
|
@end defun
|
|
|
|
@findex Inferior.write_memory
|
|
@defun Inferior.write_memory (address, buffer @r{[}, length@r{]})
|
|
Write the contents of @var{buffer} to the inferior, starting at
|
|
@var{address}. The @var{buffer} parameter must be a Python object
|
|
which supports the buffer protocol, i.e., a string, an array or the
|
|
object returned from @code{Inferior.read_memory}. If given, @var{length}
|
|
determines the number of bytes from @var{buffer} to be written.
|
|
@end defun
|
|
|
|
@findex gdb.search_memory
|
|
@defun Inferior.search_memory (address, length, pattern)
|
|
Search a region of the inferior memory starting at @var{address} with
|
|
the given @var{length} using the search pattern supplied in
|
|
@var{pattern}. The @var{pattern} parameter must be a Python object
|
|
which supports the buffer protocol, i.e., a string, an array or the
|
|
object returned from @code{gdb.read_memory}. Returns a Python @code{Long}
|
|
containing the address where the pattern was found, or @code{None} if
|
|
the pattern could not be found.
|
|
@end defun
|
|
@end table
|
|
|
|
@node Events In Python
|
|
@subsubsection Events In Python
|
|
@cindex inferior events in Python
|
|
|
|
@value{GDBN} provides a general event facility so that Python code can be
|
|
notified of various state changes, particularly changes that occur in
|
|
the inferior.
|
|
|
|
An @dfn{event} is just an object that describes some state change. The
|
|
type of the object and its attributes will vary depending on the details
|
|
of the change. All the existing events are described below.
|
|
|
|
In order to be notified of an event, you must register an event handler
|
|
with an @dfn{event registry}. An event registry is an object in the
|
|
@code{gdb.events} module which dispatches particular events. A registry
|
|
provides methods to register and unregister event handlers:
|
|
|
|
@table @code
|
|
@defun EventRegistry.connect (object)
|
|
Add the given callable @var{object} to the registry. This object will be
|
|
called when an event corresponding to this registry occurs.
|
|
@end defun
|
|
|
|
@defun EventRegistry.disconnect (object)
|
|
Remove the given @var{object} from the registry. Once removed, the object
|
|
will no longer receive notifications of events.
|
|
@end defun
|
|
@end table
|
|
|
|
Here is an example:
|
|
|
|
@smallexample
|
|
def exit_handler (event):
|
|
print "event type: exit"
|
|
print "exit code: %d" % (event.exit_code)
|
|
|
|
gdb.events.exited.connect (exit_handler)
|
|
@end smallexample
|
|
|
|
In the above example we connect our handler @code{exit_handler} to the
|
|
registry @code{events.exited}. Once connected, @code{exit_handler} gets
|
|
called when the inferior exits. The argument @dfn{event} in this example is
|
|
of type @code{gdb.ExitedEvent}. As you can see in the example the
|
|
@code{ExitedEvent} object has an attribute which indicates the exit code of
|
|
the inferior.
|
|
|
|
The following is a listing of the event registries that are available and
|
|
details of the events they emit:
|
|
|
|
@table @code
|
|
|
|
@item events.cont
|
|
Emits @code{gdb.ThreadEvent}.
|
|
|
|
Some events can be thread specific when @value{GDBN} is running in non-stop
|
|
mode. When represented in Python, these events all extend
|
|
@code{gdb.ThreadEvent}. Note, this event is not emitted directly; instead,
|
|
events which are emitted by this or other modules might extend this event.
|
|
Examples of these events are @code{gdb.BreakpointEvent} and
|
|
@code{gdb.ContinueEvent}.
|
|
|
|
@table @code
|
|
@defvar ThreadEvent.inferior_thread
|
|
In non-stop mode this attribute will be set to the specific thread which was
|
|
involved in the emitted event. Otherwise, it will be set to @code{None}.
|
|
@end defvar
|
|
@end table
|
|
|
|
Emits @code{gdb.ContinueEvent} which extends @code{gdb.ThreadEvent}.
|
|
|
|
This event indicates that the inferior has been continued after a stop. For
|
|
inherited attribute refer to @code{gdb.ThreadEvent} above.
|
|
|
|
@item events.exited
|
|
Emits @code{events.ExitedEvent} which indicates that the inferior has exited.
|
|
@code{events.ExitedEvent} has two attributes:
|
|
@table @code
|
|
@defvar ExitedEvent.exit_code
|
|
An integer representing the exit code, if available, which the inferior
|
|
has returned. (The exit code could be unavailable if, for example,
|
|
@value{GDBN} detaches from the inferior.) If the exit code is unavailable,
|
|
the attribute does not exist.
|
|
@end defvar
|
|
@defvar ExitedEvent inferior
|
|
A reference to the inferior which triggered the @code{exited} event.
|
|
@end defvar
|
|
@end table
|
|
|
|
@item events.stop
|
|
Emits @code{gdb.StopEvent} which extends @code{gdb.ThreadEvent}.
|
|
|
|
Indicates that the inferior has stopped. All events emitted by this registry
|
|
extend StopEvent. As a child of @code{gdb.ThreadEvent}, @code{gdb.StopEvent}
|
|
will indicate the stopped thread when @value{GDBN} is running in non-stop
|
|
mode. Refer to @code{gdb.ThreadEvent} above for more details.
|
|
|
|
Emits @code{gdb.SignalEvent} which extends @code{gdb.StopEvent}.
|
|
|
|
This event indicates that the inferior or one of its threads has received as
|
|
signal. @code{gdb.SignalEvent} has the following attributes:
|
|
|
|
@table @code
|
|
@defvar SignalEvent.stop_signal
|
|
A string representing the signal received by the inferior. A list of possible
|
|
signal values can be obtained by running the command @code{info signals} in
|
|
the @value{GDBN} command prompt.
|
|
@end defvar
|
|
@end table
|
|
|
|
Also emits @code{gdb.BreakpointEvent} which extends @code{gdb.StopEvent}.
|
|
|
|
@code{gdb.BreakpointEvent} event indicates that one or more breakpoints have
|
|
been hit, and has the following attributes:
|
|
|
|
@table @code
|
|
@defvar BreakpointEvent.breakpoints
|
|
A sequence containing references to all the breakpoints (type
|
|
@code{gdb.Breakpoint}) that were hit.
|
|
@xref{Breakpoints In Python}, for details of the @code{gdb.Breakpoint} object.
|
|
@end defvar
|
|
@defvar BreakpointEvent.breakpoint
|
|
A reference to the first breakpoint that was hit.
|
|
This function is maintained for backward compatibility and is now deprecated
|
|
in favor of the @code{gdb.BreakpointEvent.breakpoints} attribute.
|
|
@end defvar
|
|
@end table
|
|
|
|
@item events.new_objfile
|
|
Emits @code{gdb.NewObjFileEvent} which indicates that a new object file has
|
|
been loaded by @value{GDBN}. @code{gdb.NewObjFileEvent} has one attribute:
|
|
|
|
@table @code
|
|
@defvar NewObjFileEvent.new_objfile
|
|
A reference to the object file (@code{gdb.Objfile}) which has been loaded.
|
|
@xref{Objfiles In Python}, for details of the @code{gdb.Objfile} object.
|
|
@end defvar
|
|
@end table
|
|
|
|
@end table
|
|
|
|
@node Threads In Python
|
|
@subsubsection Threads In Python
|
|
@cindex threads in python
|
|
|
|
@findex gdb.InferiorThread
|
|
Python scripts can access information about, and manipulate inferior threads
|
|
controlled by @value{GDBN}, via objects of the @code{gdb.InferiorThread} class.
|
|
|
|
The following thread-related functions are available in the @code{gdb}
|
|
module:
|
|
|
|
@findex gdb.selected_thread
|
|
@defun gdb.selected_thread ()
|
|
This function returns the thread object for the selected thread. If there
|
|
is no selected thread, this will return @code{None}.
|
|
@end defun
|
|
|
|
A @code{gdb.InferiorThread} object has the following attributes:
|
|
|
|
@table @code
|
|
@defvar InferiorThread.name
|
|
The name of the thread. If the user specified a name using
|
|
@code{thread name}, then this returns that name. Otherwise, if an
|
|
OS-supplied name is available, then it is returned. Otherwise, this
|
|
returns @code{None}.
|
|
|
|
This attribute can be assigned to. The new value must be a string
|
|
object, which sets the new name, or @code{None}, which removes any
|
|
user-specified thread name.
|
|
@end defvar
|
|
|
|
@defvar InferiorThread.num
|
|
ID of the thread, as assigned by GDB.
|
|
@end defvar
|
|
|
|
@defvar InferiorThread.ptid
|
|
ID of the thread, as assigned by the operating system. This attribute is a
|
|
tuple containing three integers. The first is the Process ID (PID); the second
|
|
is the Lightweight Process ID (LWPID), and the third is the Thread ID (TID).
|
|
Either the LWPID or TID may be 0, which indicates that the operating system
|
|
does not use that identifier.
|
|
@end defvar
|
|
@end table
|
|
|
|
A @code{gdb.InferiorThread} object has the following methods:
|
|
|
|
@table @code
|
|
@defun InferiorThread.is_valid ()
|
|
Returns @code{True} if the @code{gdb.InferiorThread} object is valid,
|
|
@code{False} if not. A @code{gdb.InferiorThread} object will become
|
|
invalid if the thread exits, or the inferior that the thread belongs
|
|
is deleted. All other @code{gdb.InferiorThread} methods will throw an
|
|
exception if it is invalid at the time the method is called.
|
|
@end defun
|
|
|
|
@defun InferiorThread.switch ()
|
|
This changes @value{GDBN}'s currently selected thread to the one represented
|
|
by this object.
|
|
@end defun
|
|
|
|
@defun InferiorThread.is_stopped ()
|
|
Return a Boolean indicating whether the thread is stopped.
|
|
@end defun
|
|
|
|
@defun InferiorThread.is_running ()
|
|
Return a Boolean indicating whether the thread is running.
|
|
@end defun
|
|
|
|
@defun InferiorThread.is_exited ()
|
|
Return a Boolean indicating whether the thread is exited.
|
|
@end defun
|
|
@end table
|
|
|
|
@node Commands In Python
|
|
@subsubsection Commands In Python
|
|
|
|
@cindex commands in python
|
|
@cindex python commands
|
|
You can implement new @value{GDBN} CLI commands in Python. A CLI
|
|
command is implemented using an instance of the @code{gdb.Command}
|
|
class, most commonly using a subclass.
|
|
|
|
@defun Command.__init__ (name, @var{command_class} @r{[}, @var{completer_class} @r{[}, @var{prefix}@r{]]})
|
|
The object initializer for @code{Command} registers the new command
|
|
with @value{GDBN}. This initializer is normally invoked from the
|
|
subclass' own @code{__init__} method.
|
|
|
|
@var{name} is the name of the command. If @var{name} consists of
|
|
multiple words, then the initial words are looked for as prefix
|
|
commands. In this case, if one of the prefix commands does not exist,
|
|
an exception is raised.
|
|
|
|
There is no support for multi-line commands.
|
|
|
|
@var{command_class} should be one of the @samp{COMMAND_} constants
|
|
defined below. This argument tells @value{GDBN} how to categorize the
|
|
new command in the help system.
|
|
|
|
@var{completer_class} is an optional argument. If given, it should be
|
|
one of the @samp{COMPLETE_} constants defined below. This argument
|
|
tells @value{GDBN} how to perform completion for this command. If not
|
|
given, @value{GDBN} will attempt to complete using the object's
|
|
@code{complete} method (see below); if no such method is found, an
|
|
error will occur when completion is attempted.
|
|
|
|
@var{prefix} is an optional argument. If @code{True}, then the new
|
|
command is a prefix command; sub-commands of this command may be
|
|
registered.
|
|
|
|
The help text for the new command is taken from the Python
|
|
documentation string for the command's class, if there is one. If no
|
|
documentation string is provided, the default value ``This command is
|
|
not documented.'' is used.
|
|
@end defun
|
|
|
|
@cindex don't repeat Python command
|
|
@defun Command.dont_repeat ()
|
|
By default, a @value{GDBN} command is repeated when the user enters a
|
|
blank line at the command prompt. A command can suppress this
|
|
behavior by invoking the @code{dont_repeat} method. This is similar
|
|
to the user command @code{dont-repeat}, see @ref{Define, dont-repeat}.
|
|
@end defun
|
|
|
|
@defun Command.invoke (argument, from_tty)
|
|
This method is called by @value{GDBN} when this command is invoked.
|
|
|
|
@var{argument} is a string. It is the argument to the command, after
|
|
leading and trailing whitespace has been stripped.
|
|
|
|
@var{from_tty} is a boolean argument. When true, this means that the
|
|
command was entered by the user at the terminal; when false it means
|
|
that the command came from elsewhere.
|
|
|
|
If this method throws an exception, it is turned into a @value{GDBN}
|
|
@code{error} call. Otherwise, the return value is ignored.
|
|
|
|
@findex gdb.string_to_argv
|
|
To break @var{argument} up into an argv-like string use
|
|
@code{gdb.string_to_argv}. This function behaves identically to
|
|
@value{GDBN}'s internal argument lexer @code{buildargv}.
|
|
It is recommended to use this for consistency.
|
|
Arguments are separated by spaces and may be quoted.
|
|
Example:
|
|
|
|
@smallexample
|
|
print gdb.string_to_argv ("1 2\ \\\"3 '4 \"5' \"6 '7\"")
|
|
['1', '2 "3', '4 "5', "6 '7"]
|
|
@end smallexample
|
|
|
|
@end defun
|
|
|
|
@cindex completion of Python commands
|
|
@defun Command.complete (text, word)
|
|
This method is called by @value{GDBN} when the user attempts
|
|
completion on this command. All forms of completion are handled by
|
|
this method, that is, the @key{TAB} and @key{M-?} key bindings
|
|
(@pxref{Completion}), and the @code{complete} command (@pxref{Help,
|
|
complete}).
|
|
|
|
The arguments @var{text} and @var{word} are both strings. @var{text}
|
|
holds the complete command line up to the cursor's location.
|
|
@var{word} holds the last word of the command line; this is computed
|
|
using a word-breaking heuristic.
|
|
|
|
The @code{complete} method can return several values:
|
|
@itemize @bullet
|
|
@item
|
|
If the return value is a sequence, the contents of the sequence are
|
|
used as the completions. It is up to @code{complete} to ensure that the
|
|
contents actually do complete the word. A zero-length sequence is
|
|
allowed, it means that there were no completions available. Only
|
|
string elements of the sequence are used; other elements in the
|
|
sequence are ignored.
|
|
|
|
@item
|
|
If the return value is one of the @samp{COMPLETE_} constants defined
|
|
below, then the corresponding @value{GDBN}-internal completion
|
|
function is invoked, and its result is used.
|
|
|
|
@item
|
|
All other results are treated as though there were no available
|
|
completions.
|
|
@end itemize
|
|
@end defun
|
|
|
|
When a new command is registered, it must be declared as a member of
|
|
some general class of commands. This is used to classify top-level
|
|
commands in the on-line help system; note that prefix commands are not
|
|
listed under their own category but rather that of their top-level
|
|
command. The available classifications are represented by constants
|
|
defined in the @code{gdb} module:
|
|
|
|
@table @code
|
|
@findex COMMAND_NONE
|
|
@findex gdb.COMMAND_NONE
|
|
@item gdb.COMMAND_NONE
|
|
The command does not belong to any particular class. A command in
|
|
this category will not be displayed in any of the help categories.
|
|
|
|
@findex COMMAND_RUNNING
|
|
@findex gdb.COMMAND_RUNNING
|
|
@item gdb.COMMAND_RUNNING
|
|
The command is related to running the inferior. For example,
|
|
@code{start}, @code{step}, and @code{continue} are in this category.
|
|
Type @kbd{help running} at the @value{GDBN} prompt to see a list of
|
|
commands in this category.
|
|
|
|
@findex COMMAND_DATA
|
|
@findex gdb.COMMAND_DATA
|
|
@item gdb.COMMAND_DATA
|
|
The command is related to data or variables. For example,
|
|
@code{call}, @code{find}, and @code{print} are in this category. Type
|
|
@kbd{help data} at the @value{GDBN} prompt to see a list of commands
|
|
in this category.
|
|
|
|
@findex COMMAND_STACK
|
|
@findex gdb.COMMAND_STACK
|
|
@item gdb.COMMAND_STACK
|
|
The command has to do with manipulation of the stack. For example,
|
|
@code{backtrace}, @code{frame}, and @code{return} are in this
|
|
category. Type @kbd{help stack} at the @value{GDBN} prompt to see a
|
|
list of commands in this category.
|
|
|
|
@findex COMMAND_FILES
|
|
@findex gdb.COMMAND_FILES
|
|
@item gdb.COMMAND_FILES
|
|
This class is used for file-related commands. For example,
|
|
@code{file}, @code{list} and @code{section} are in this category.
|
|
Type @kbd{help files} at the @value{GDBN} prompt to see a list of
|
|
commands in this category.
|
|
|
|
@findex COMMAND_SUPPORT
|
|
@findex gdb.COMMAND_SUPPORT
|
|
@item gdb.COMMAND_SUPPORT
|
|
This should be used for ``support facilities'', generally meaning
|
|
things that are useful to the user when interacting with @value{GDBN},
|
|
but not related to the state of the inferior. For example,
|
|
@code{help}, @code{make}, and @code{shell} are in this category. Type
|
|
@kbd{help support} at the @value{GDBN} prompt to see a list of
|
|
commands in this category.
|
|
|
|
@findex COMMAND_STATUS
|
|
@findex gdb.COMMAND_STATUS
|
|
@item gdb.COMMAND_STATUS
|
|
The command is an @samp{info}-related command, that is, related to the
|
|
state of @value{GDBN} itself. For example, @code{info}, @code{macro},
|
|
and @code{show} are in this category. Type @kbd{help status} at the
|
|
@value{GDBN} prompt to see a list of commands in this category.
|
|
|
|
@findex COMMAND_BREAKPOINTS
|
|
@findex gdb.COMMAND_BREAKPOINTS
|
|
@item gdb.COMMAND_BREAKPOINTS
|
|
The command has to do with breakpoints. For example, @code{break},
|
|
@code{clear}, and @code{delete} are in this category. Type @kbd{help
|
|
breakpoints} at the @value{GDBN} prompt to see a list of commands in
|
|
this category.
|
|
|
|
@findex COMMAND_TRACEPOINTS
|
|
@findex gdb.COMMAND_TRACEPOINTS
|
|
@item gdb.COMMAND_TRACEPOINTS
|
|
The command has to do with tracepoints. For example, @code{trace},
|
|
@code{actions}, and @code{tfind} are in this category. Type
|
|
@kbd{help tracepoints} at the @value{GDBN} prompt to see a list of
|
|
commands in this category.
|
|
|
|
@findex COMMAND_USER
|
|
@findex gdb.COMMAND_USER
|
|
@item gdb.COMMAND_USER
|
|
The command is a general purpose command for the user, and typically
|
|
does not fit in one of the other categories.
|
|
Type @kbd{help user-defined} at the @value{GDBN} prompt to see
|
|
a list of commands in this category, as well as the list of gdb macros
|
|
(@pxref{Sequences}).
|
|
|
|
@findex COMMAND_OBSCURE
|
|
@findex gdb.COMMAND_OBSCURE
|
|
@item gdb.COMMAND_OBSCURE
|
|
The command is only used in unusual circumstances, or is not of
|
|
general interest to users. For example, @code{checkpoint},
|
|
@code{fork}, and @code{stop} are in this category. Type @kbd{help
|
|
obscure} at the @value{GDBN} prompt to see a list of commands in this
|
|
category.
|
|
|
|
@findex COMMAND_MAINTENANCE
|
|
@findex gdb.COMMAND_MAINTENANCE
|
|
@item gdb.COMMAND_MAINTENANCE
|
|
The command is only useful to @value{GDBN} maintainers. The
|
|
@code{maintenance} and @code{flushregs} commands are in this category.
|
|
Type @kbd{help internals} at the @value{GDBN} prompt to see a list of
|
|
commands in this category.
|
|
@end table
|
|
|
|
A new command can use a predefined completion function, either by
|
|
specifying it via an argument at initialization, or by returning it
|
|
from the @code{complete} method. These predefined completion
|
|
constants are all defined in the @code{gdb} module:
|
|
|
|
@table @code
|
|
@findex COMPLETE_NONE
|
|
@findex gdb.COMPLETE_NONE
|
|
@item gdb.COMPLETE_NONE
|
|
This constant means that no completion should be done.
|
|
|
|
@findex COMPLETE_FILENAME
|
|
@findex gdb.COMPLETE_FILENAME
|
|
@item gdb.COMPLETE_FILENAME
|
|
This constant means that filename completion should be performed.
|
|
|
|
@findex COMPLETE_LOCATION
|
|
@findex gdb.COMPLETE_LOCATION
|
|
@item gdb.COMPLETE_LOCATION
|
|
This constant means that location completion should be done.
|
|
@xref{Specify Location}.
|
|
|
|
@findex COMPLETE_COMMAND
|
|
@findex gdb.COMPLETE_COMMAND
|
|
@item gdb.COMPLETE_COMMAND
|
|
This constant means that completion should examine @value{GDBN}
|
|
command names.
|
|
|
|
@findex COMPLETE_SYMBOL
|
|
@findex gdb.COMPLETE_SYMBOL
|
|
@item gdb.COMPLETE_SYMBOL
|
|
This constant means that completion should be done using symbol names
|
|
as the source.
|
|
@end table
|
|
|
|
The following code snippet shows how a trivial CLI command can be
|
|
implemented in Python:
|
|
|
|
@smallexample
|
|
class HelloWorld (gdb.Command):
|
|
"""Greet the whole world."""
|
|
|
|
def __init__ (self):
|
|
super (HelloWorld, self).__init__ ("hello-world", gdb.COMMAND_USER)
|
|
|
|
def invoke (self, arg, from_tty):
|
|
print "Hello, World!"
|
|
|
|
HelloWorld ()
|
|
@end smallexample
|
|
|
|
The last line instantiates the class, and is necessary to trigger the
|
|
registration of the command with @value{GDBN}. Depending on how the
|
|
Python code is read into @value{GDBN}, you may need to import the
|
|
@code{gdb} module explicitly.
|
|
|
|
@node Parameters In Python
|
|
@subsubsection Parameters In Python
|
|
|
|
@cindex parameters in python
|
|
@cindex python parameters
|
|
@tindex gdb.Parameter
|
|
@tindex Parameter
|
|
You can implement new @value{GDBN} parameters using Python. A new
|
|
parameter is implemented as an instance of the @code{gdb.Parameter}
|
|
class.
|
|
|
|
Parameters are exposed to the user via the @code{set} and
|
|
@code{show} commands. @xref{Help}.
|
|
|
|
There are many parameters that already exist and can be set in
|
|
@value{GDBN}. Two examples are: @code{set follow fork} and
|
|
@code{set charset}. Setting these parameters influences certain
|
|
behavior in @value{GDBN}. Similarly, you can define parameters that
|
|
can be used to influence behavior in custom Python scripts and commands.
|
|
|
|
@defun Parameter.__init__ (name, @var{command-class}, @var{parameter-class} @r{[}, @var{enum-sequence}@r{]})
|
|
The object initializer for @code{Parameter} registers the new
|
|
parameter with @value{GDBN}. This initializer is normally invoked
|
|
from the subclass' own @code{__init__} method.
|
|
|
|
@var{name} is the name of the new parameter. If @var{name} consists
|
|
of multiple words, then the initial words are looked for as prefix
|
|
parameters. An example of this can be illustrated with the
|
|
@code{set print} set of parameters. If @var{name} is
|
|
@code{print foo}, then @code{print} will be searched as the prefix
|
|
parameter. In this case the parameter can subsequently be accessed in
|
|
@value{GDBN} as @code{set print foo}.
|
|
|
|
If @var{name} consists of multiple words, and no prefix parameter group
|
|
can be found, an exception is raised.
|
|
|
|
@var{command-class} should be one of the @samp{COMMAND_} constants
|
|
(@pxref{Commands In Python}). This argument tells @value{GDBN} how to
|
|
categorize the new parameter in the help system.
|
|
|
|
@var{parameter-class} should be one of the @samp{PARAM_} constants
|
|
defined below. This argument tells @value{GDBN} the type of the new
|
|
parameter; this information is used for input validation and
|
|
completion.
|
|
|
|
If @var{parameter-class} is @code{PARAM_ENUM}, then
|
|
@var{enum-sequence} must be a sequence of strings. These strings
|
|
represent the possible values for the parameter.
|
|
|
|
If @var{parameter-class} is not @code{PARAM_ENUM}, then the presence
|
|
of a fourth argument will cause an exception to be thrown.
|
|
|
|
The help text for the new parameter is taken from the Python
|
|
documentation string for the parameter's class, if there is one. If
|
|
there is no documentation string, a default value is used.
|
|
@end defun
|
|
|
|
@defvar Parameter.set_doc
|
|
If this attribute exists, and is a string, then its value is used as
|
|
the help text for this parameter's @code{set} command. The value is
|
|
examined when @code{Parameter.__init__} is invoked; subsequent changes
|
|
have no effect.
|
|
@end defvar
|
|
|
|
@defvar Parameter.show_doc
|
|
If this attribute exists, and is a string, then its value is used as
|
|
the help text for this parameter's @code{show} command. The value is
|
|
examined when @code{Parameter.__init__} is invoked; subsequent changes
|
|
have no effect.
|
|
@end defvar
|
|
|
|
@defvar Parameter.value
|
|
The @code{value} attribute holds the underlying value of the
|
|
parameter. It can be read and assigned to just as any other
|
|
attribute. @value{GDBN} does validation when assignments are made.
|
|
@end defvar
|
|
|
|
There are two methods that should be implemented in any
|
|
@code{Parameter} class. These are:
|
|
|
|
@defun Parameter.get_set_string (self)
|
|
@value{GDBN} will call this method when a @var{parameter}'s value has
|
|
been changed via the @code{set} API (for example, @kbd{set foo off}).
|
|
The @code{value} attribute has already been populated with the new
|
|
value and may be used in output. This method must return a string.
|
|
@end defun
|
|
|
|
@defun Parameter.get_show_string (self, svalue)
|
|
@value{GDBN} will call this method when a @var{parameter}'s
|
|
@code{show} API has been invoked (for example, @kbd{show foo}). The
|
|
argument @code{svalue} receives the string representation of the
|
|
current value. This method must return a string.
|
|
@end defun
|
|
|
|
When a new parameter is defined, its type must be specified. The
|
|
available types are represented by constants defined in the @code{gdb}
|
|
module:
|
|
|
|
@table @code
|
|
@findex PARAM_BOOLEAN
|
|
@findex gdb.PARAM_BOOLEAN
|
|
@item gdb.PARAM_BOOLEAN
|
|
The value is a plain boolean. The Python boolean values, @code{True}
|
|
and @code{False} are the only valid values.
|
|
|
|
@findex PARAM_AUTO_BOOLEAN
|
|
@findex gdb.PARAM_AUTO_BOOLEAN
|
|
@item gdb.PARAM_AUTO_BOOLEAN
|
|
The value has three possible states: true, false, and @samp{auto}. In
|
|
Python, true and false are represented using boolean constants, and
|
|
@samp{auto} is represented using @code{None}.
|
|
|
|
@findex PARAM_UINTEGER
|
|
@findex gdb.PARAM_UINTEGER
|
|
@item gdb.PARAM_UINTEGER
|
|
The value is an unsigned integer. The value of 0 should be
|
|
interpreted to mean ``unlimited''.
|
|
|
|
@findex PARAM_INTEGER
|
|
@findex gdb.PARAM_INTEGER
|
|
@item gdb.PARAM_INTEGER
|
|
The value is a signed integer. The value of 0 should be interpreted
|
|
to mean ``unlimited''.
|
|
|
|
@findex PARAM_STRING
|
|
@findex gdb.PARAM_STRING
|
|
@item gdb.PARAM_STRING
|
|
The value is a string. When the user modifies the string, any escape
|
|
sequences, such as @samp{\t}, @samp{\f}, and octal escapes, are
|
|
translated into corresponding characters and encoded into the current
|
|
host charset.
|
|
|
|
@findex PARAM_STRING_NOESCAPE
|
|
@findex gdb.PARAM_STRING_NOESCAPE
|
|
@item gdb.PARAM_STRING_NOESCAPE
|
|
The value is a string. When the user modifies the string, escapes are
|
|
passed through untranslated.
|
|
|
|
@findex PARAM_OPTIONAL_FILENAME
|
|
@findex gdb.PARAM_OPTIONAL_FILENAME
|
|
@item gdb.PARAM_OPTIONAL_FILENAME
|
|
The value is a either a filename (a string), or @code{None}.
|
|
|
|
@findex PARAM_FILENAME
|
|
@findex gdb.PARAM_FILENAME
|
|
@item gdb.PARAM_FILENAME
|
|
The value is a filename. This is just like
|
|
@code{PARAM_STRING_NOESCAPE}, but uses file names for completion.
|
|
|
|
@findex PARAM_ZINTEGER
|
|
@findex gdb.PARAM_ZINTEGER
|
|
@item gdb.PARAM_ZINTEGER
|
|
The value is an integer. This is like @code{PARAM_INTEGER}, except 0
|
|
is interpreted as itself.
|
|
|
|
@findex PARAM_ENUM
|
|
@findex gdb.PARAM_ENUM
|
|
@item gdb.PARAM_ENUM
|
|
The value is a string, which must be one of a collection string
|
|
constants provided when the parameter is created.
|
|
@end table
|
|
|
|
@node Functions In Python
|
|
@subsubsection Writing new convenience functions
|
|
|
|
@cindex writing convenience functions
|
|
@cindex convenience functions in python
|
|
@cindex python convenience functions
|
|
@tindex gdb.Function
|
|
@tindex Function
|
|
You can implement new convenience functions (@pxref{Convenience Vars})
|
|
in Python. A convenience function is an instance of a subclass of the
|
|
class @code{gdb.Function}.
|
|
|
|
@defun Function.__init__ (name)
|
|
The initializer for @code{Function} registers the new function with
|
|
@value{GDBN}. The argument @var{name} is the name of the function,
|
|
a string. The function will be visible to the user as a convenience
|
|
variable of type @code{internal function}, whose name is the same as
|
|
the given @var{name}.
|
|
|
|
The documentation for the new function is taken from the documentation
|
|
string for the new class.
|
|
@end defun
|
|
|
|
@defun Function.invoke (@var{*args})
|
|
When a convenience function is evaluated, its arguments are converted
|
|
to instances of @code{gdb.Value}, and then the function's
|
|
@code{invoke} method is called. Note that @value{GDBN} does not
|
|
predetermine the arity of convenience functions. Instead, all
|
|
available arguments are passed to @code{invoke}, following the
|
|
standard Python calling convention. In particular, a convenience
|
|
function can have default values for parameters without ill effect.
|
|
|
|
The return value of this method is used as its value in the enclosing
|
|
expression. If an ordinary Python value is returned, it is converted
|
|
to a @code{gdb.Value} following the usual rules.
|
|
@end defun
|
|
|
|
The following code snippet shows how a trivial convenience function can
|
|
be implemented in Python:
|
|
|
|
@smallexample
|
|
class Greet (gdb.Function):
|
|
"""Return string to greet someone.
|
|
Takes a name as argument."""
|
|
|
|
def __init__ (self):
|
|
super (Greet, self).__init__ ("greet")
|
|
|
|
def invoke (self, name):
|
|
return "Hello, %s!" % name.string ()
|
|
|
|
Greet ()
|
|
@end smallexample
|
|
|
|
The last line instantiates the class, and is necessary to trigger the
|
|
registration of the function with @value{GDBN}. Depending on how the
|
|
Python code is read into @value{GDBN}, you may need to import the
|
|
@code{gdb} module explicitly.
|
|
|
|
@node Progspaces In Python
|
|
@subsubsection Program Spaces In Python
|
|
|
|
@cindex progspaces in python
|
|
@tindex gdb.Progspace
|
|
@tindex Progspace
|
|
A program space, or @dfn{progspace}, represents a symbolic view
|
|
of an address space.
|
|
It consists of all of the objfiles of the program.
|
|
@xref{Objfiles In Python}.
|
|
@xref{Inferiors and Programs, program spaces}, for more details
|
|
about program spaces.
|
|
|
|
The following progspace-related functions are available in the
|
|
@code{gdb} module:
|
|
|
|
@findex gdb.current_progspace
|
|
@defun gdb.current_progspace ()
|
|
This function returns the program space of the currently selected inferior.
|
|
@xref{Inferiors and Programs}.
|
|
@end defun
|
|
|
|
@findex gdb.progspaces
|
|
@defun gdb.progspaces ()
|
|
Return a sequence of all the progspaces currently known to @value{GDBN}.
|
|
@end defun
|
|
|
|
Each progspace is represented by an instance of the @code{gdb.Progspace}
|
|
class.
|
|
|
|
@defvar Progspace.filename
|
|
The file name of the progspace as a string.
|
|
@end defvar
|
|
|
|
@defvar Progspace.pretty_printers
|
|
The @code{pretty_printers} attribute is a list of functions. It is
|
|
used to look up pretty-printers. A @code{Value} is passed to each
|
|
function in order; if the function returns @code{None}, then the
|
|
search continues. Otherwise, the return value should be an object
|
|
which is used to format the value. @xref{Pretty Printing API}, for more
|
|
information.
|
|
@end defvar
|
|
|
|
@node Objfiles In Python
|
|
@subsubsection Objfiles In Python
|
|
|
|
@cindex objfiles in python
|
|
@tindex gdb.Objfile
|
|
@tindex Objfile
|
|
@value{GDBN} loads symbols for an inferior from various
|
|
symbol-containing files (@pxref{Files}). These include the primary
|
|
executable file, any shared libraries used by the inferior, and any
|
|
separate debug info files (@pxref{Separate Debug Files}).
|
|
@value{GDBN} calls these symbol-containing files @dfn{objfiles}.
|
|
|
|
The following objfile-related functions are available in the
|
|
@code{gdb} module:
|
|
|
|
@findex gdb.current_objfile
|
|
@defun gdb.current_objfile ()
|
|
When auto-loading a Python script (@pxref{Python Auto-loading}), @value{GDBN}
|
|
sets the ``current objfile'' to the corresponding objfile. This
|
|
function returns the current objfile. If there is no current objfile,
|
|
this function returns @code{None}.
|
|
@end defun
|
|
|
|
@findex gdb.objfiles
|
|
@defun gdb.objfiles ()
|
|
Return a sequence of all the objfiles current known to @value{GDBN}.
|
|
@xref{Objfiles In Python}.
|
|
@end defun
|
|
|
|
Each objfile is represented by an instance of the @code{gdb.Objfile}
|
|
class.
|
|
|
|
@defvar Objfile.filename
|
|
The file name of the objfile as a string.
|
|
@end defvar
|
|
|
|
@defvar Objfile.pretty_printers
|
|
The @code{pretty_printers} attribute is a list of functions. It is
|
|
used to look up pretty-printers. A @code{Value} is passed to each
|
|
function in order; if the function returns @code{None}, then the
|
|
search continues. Otherwise, the return value should be an object
|
|
which is used to format the value. @xref{Pretty Printing API}, for more
|
|
information.
|
|
@end defvar
|
|
|
|
A @code{gdb.Objfile} object has the following methods:
|
|
|
|
@defun Objfile.is_valid ()
|
|
Returns @code{True} if the @code{gdb.Objfile} object is valid,
|
|
@code{False} if not. A @code{gdb.Objfile} object can become invalid
|
|
if the object file it refers to is not loaded in @value{GDBN} any
|
|
longer. All other @code{gdb.Objfile} methods will throw an exception
|
|
if it is invalid at the time the method is called.
|
|
@end defun
|
|
|
|
@node Frames In Python
|
|
@subsubsection Accessing inferior stack frames from Python.
|
|
|
|
@cindex frames in python
|
|
When the debugged program stops, @value{GDBN} is able to analyze its call
|
|
stack (@pxref{Frames,,Stack frames}). The @code{gdb.Frame} class
|
|
represents a frame in the stack. A @code{gdb.Frame} object is only valid
|
|
while its corresponding frame exists in the inferior's stack. If you try
|
|
to use an invalid frame object, @value{GDBN} will throw a @code{gdb.error}
|
|
exception (@pxref{Exception Handling}).
|
|
|
|
Two @code{gdb.Frame} objects can be compared for equality with the @code{==}
|
|
operator, like:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) python print gdb.newest_frame() == gdb.selected_frame ()
|
|
True
|
|
@end smallexample
|
|
|
|
The following frame-related functions are available in the @code{gdb} module:
|
|
|
|
@findex gdb.selected_frame
|
|
@defun gdb.selected_frame ()
|
|
Return the selected frame object. (@pxref{Selection,,Selecting a Frame}).
|
|
@end defun
|
|
|
|
@findex gdb.newest_frame
|
|
@defun gdb.newest_frame ()
|
|
Return the newest frame object for the selected thread.
|
|
@end defun
|
|
|
|
@defun gdb.frame_stop_reason_string (reason)
|
|
Return a string explaining the reason why @value{GDBN} stopped unwinding
|
|
frames, as expressed by the given @var{reason} code (an integer, see the
|
|
@code{unwind_stop_reason} method further down in this section).
|
|
@end defun
|
|
|
|
A @code{gdb.Frame} object has the following methods:
|
|
|
|
@table @code
|
|
@defun Frame.is_valid ()
|
|
Returns true if the @code{gdb.Frame} object is valid, false if not.
|
|
A frame object can become invalid if the frame it refers to doesn't
|
|
exist anymore in the inferior. All @code{gdb.Frame} methods will throw
|
|
an exception if it is invalid at the time the method is called.
|
|
@end defun
|
|
|
|
@defun Frame.name ()
|
|
Returns the function name of the frame, or @code{None} if it can't be
|
|
obtained.
|
|
@end defun
|
|
|
|
@defun Frame.type ()
|
|
Returns the type of the frame. The value can be one of:
|
|
@table @code
|
|
@item gdb.NORMAL_FRAME
|
|
An ordinary stack frame.
|
|
|
|
@item gdb.DUMMY_FRAME
|
|
A fake stack frame that was created by @value{GDBN} when performing an
|
|
inferior function call.
|
|
|
|
@item gdb.INLINE_FRAME
|
|
A frame representing an inlined function. The function was inlined
|
|
into a @code{gdb.NORMAL_FRAME} that is older than this one.
|
|
|
|
@item gdb.TAILCALL_FRAME
|
|
A frame representing a tail call. @xref{Tail Call Frames}.
|
|
|
|
@item gdb.SIGTRAMP_FRAME
|
|
A signal trampoline frame. This is the frame created by the OS when
|
|
it calls into a signal handler.
|
|
|
|
@item gdb.ARCH_FRAME
|
|
A fake stack frame representing a cross-architecture call.
|
|
|
|
@item gdb.SENTINEL_FRAME
|
|
This is like @code{gdb.NORMAL_FRAME}, but it is only used for the
|
|
newest frame.
|
|
@end table
|
|
@end defun
|
|
|
|
@defun Frame.unwind_stop_reason ()
|
|
Return an integer representing the reason why it's not possible to find
|
|
more frames toward the outermost frame. Use
|
|
@code{gdb.frame_stop_reason_string} to convert the value returned by this
|
|
function to a string. The value can be one of:
|
|
|
|
@table @code
|
|
@item gdb.FRAME_UNWIND_NO_REASON
|
|
No particular reason (older frames should be available).
|
|
|
|
@item gdb.FRAME_UNWIND_NULL_ID
|
|
The previous frame's analyzer returns an invalid result.
|
|
|
|
@item gdb.FRAME_UNWIND_OUTERMOST
|
|
This frame is the outermost.
|
|
|
|
@item gdb.FRAME_UNWIND_UNAVAILABLE
|
|
Cannot unwind further, because that would require knowing the
|
|
values of registers or memory that have not been collected.
|
|
|
|
@item gdb.FRAME_UNWIND_INNER_ID
|
|
This frame ID looks like it ought to belong to a NEXT frame,
|
|
but we got it for a PREV frame. Normally, this is a sign of
|
|
unwinder failure. It could also indicate stack corruption.
|
|
|
|
@item gdb.FRAME_UNWIND_SAME_ID
|
|
This frame has the same ID as the previous one. That means
|
|
that unwinding further would almost certainly give us another
|
|
frame with exactly the same ID, so break the chain. Normally,
|
|
this is a sign of unwinder failure. It could also indicate
|
|
stack corruption.
|
|
|
|
@item gdb.FRAME_UNWIND_NO_SAVED_PC
|
|
The frame unwinder did not find any saved PC, but we needed
|
|
one to unwind further.
|
|
|
|
@item gdb.FRAME_UNWIND_FIRST_ERROR
|
|
Any stop reason greater or equal to this value indicates some kind
|
|
of error. This special value facilitates writing code that tests
|
|
for errors in unwinding in a way that will work correctly even if
|
|
the list of the other values is modified in future @value{GDBN}
|
|
versions. Using it, you could write:
|
|
@smallexample
|
|
reason = gdb.selected_frame().unwind_stop_reason ()
|
|
reason_str = gdb.frame_stop_reason_string (reason)
|
|
if reason >= gdb.FRAME_UNWIND_FIRST_ERROR:
|
|
print "An error occured: %s" % reason_str
|
|
@end smallexample
|
|
@end table
|
|
|
|
@end defun
|
|
|
|
@defun Frame.pc ()
|
|
Returns the frame's resume address.
|
|
@end defun
|
|
|
|
@defun Frame.block ()
|
|
Return the frame's code block. @xref{Blocks In Python}.
|
|
@end defun
|
|
|
|
@defun Frame.function ()
|
|
Return the symbol for the function corresponding to this frame.
|
|
@xref{Symbols In Python}.
|
|
@end defun
|
|
|
|
@defun Frame.older ()
|
|
Return the frame that called this frame.
|
|
@end defun
|
|
|
|
@defun Frame.newer ()
|
|
Return the frame called by this frame.
|
|
@end defun
|
|
|
|
@defun Frame.find_sal ()
|
|
Return the frame's symtab and line object.
|
|
@xref{Symbol Tables In Python}.
|
|
@end defun
|
|
|
|
@defun Frame.read_var (variable @r{[}, block@r{]})
|
|
Return the value of @var{variable} in this frame. If the optional
|
|
argument @var{block} is provided, search for the variable from that
|
|
block; otherwise start at the frame's current block (which is
|
|
determined by the frame's current program counter). @var{variable}
|
|
must be a string or a @code{gdb.Symbol} object. @var{block} must be a
|
|
@code{gdb.Block} object.
|
|
@end defun
|
|
|
|
@defun Frame.select ()
|
|
Set this frame to be the selected frame. @xref{Stack, ,Examining the
|
|
Stack}.
|
|
@end defun
|
|
@end table
|
|
|
|
@node Blocks In Python
|
|
@subsubsection Accessing frame blocks from Python.
|
|
|
|
@cindex blocks in python
|
|
@tindex gdb.Block
|
|
|
|
Within each frame, @value{GDBN} maintains information on each block
|
|
stored in that frame. These blocks are organized hierarchically, and
|
|
are represented individually in Python as a @code{gdb.Block}.
|
|
Please see @ref{Frames In Python}, for a more in-depth discussion on
|
|
frames. Furthermore, see @ref{Stack, ,Examining the Stack}, for more
|
|
detailed technical information on @value{GDBN}'s book-keeping of the
|
|
stack.
|
|
|
|
A @code{gdb.Block} is iterable. The iterator returns the symbols
|
|
(@pxref{Symbols In Python}) local to the block. Python programs
|
|
should not assume that a specific block object will always contain a
|
|
given symbol, since changes in @value{GDBN} features and
|
|
infrastructure may cause symbols move across blocks in a symbol
|
|
table.
|
|
|
|
The following block-related functions are available in the @code{gdb}
|
|
module:
|
|
|
|
@findex gdb.block_for_pc
|
|
@defun gdb.block_for_pc (pc)
|
|
Return the @code{gdb.Block} containing the given @var{pc} value. If the
|
|
block cannot be found for the @var{pc} value specified, the function
|
|
will return @code{None}.
|
|
@end defun
|
|
|
|
A @code{gdb.Block} object has the following methods:
|
|
|
|
@table @code
|
|
@defun Block.is_valid ()
|
|
Returns @code{True} if the @code{gdb.Block} object is valid,
|
|
@code{False} if not. A block object can become invalid if the block it
|
|
refers to doesn't exist anymore in the inferior. All other
|
|
@code{gdb.Block} methods will throw an exception if it is invalid at
|
|
the time the method is called. The block's validity is also checked
|
|
during iteration over symbols of the block.
|
|
@end defun
|
|
@end table
|
|
|
|
A @code{gdb.Block} object has the following attributes:
|
|
|
|
@table @code
|
|
@defvar Block.start
|
|
The start address of the block. This attribute is not writable.
|
|
@end defvar
|
|
|
|
@defvar Block.end
|
|
The end address of the block. This attribute is not writable.
|
|
@end defvar
|
|
|
|
@defvar Block.function
|
|
The name of the block represented as a @code{gdb.Symbol}. If the
|
|
block is not named, then this attribute holds @code{None}. This
|
|
attribute is not writable.
|
|
@end defvar
|
|
|
|
@defvar Block.superblock
|
|
The block containing this block. If this parent block does not exist,
|
|
this attribute holds @code{None}. This attribute is not writable.
|
|
@end defvar
|
|
|
|
@defvar Block.global_block
|
|
The global block associated with this block. This attribute is not
|
|
writable.
|
|
@end defvar
|
|
|
|
@defvar Block.static_block
|
|
The static block associated with this block. This attribute is not
|
|
writable.
|
|
@end defvar
|
|
|
|
@defvar Block.is_global
|
|
@code{True} if the @code{gdb.Block} object is a global block,
|
|
@code{False} if not. This attribute is not
|
|
writable.
|
|
@end defvar
|
|
|
|
@defvar Block.is_static
|
|
@code{True} if the @code{gdb.Block} object is a static block,
|
|
@code{False} if not. This attribute is not writable.
|
|
@end defvar
|
|
@end table
|
|
|
|
@node Symbols In Python
|
|
@subsubsection Python representation of Symbols.
|
|
|
|
@cindex symbols in python
|
|
@tindex gdb.Symbol
|
|
|
|
@value{GDBN} represents every variable, function and type as an
|
|
entry in a symbol table. @xref{Symbols, ,Examining the Symbol Table}.
|
|
Similarly, Python represents these symbols in @value{GDBN} with the
|
|
@code{gdb.Symbol} object.
|
|
|
|
The following symbol-related functions are available in the @code{gdb}
|
|
module:
|
|
|
|
@findex gdb.lookup_symbol
|
|
@defun gdb.lookup_symbol (name @r{[}, block @r{[}, domain@r{]]})
|
|
This function searches for a symbol by name. The search scope can be
|
|
restricted to the parameters defined in the optional domain and block
|
|
arguments.
|
|
|
|
@var{name} is the name of the symbol. It must be a string. The
|
|
optional @var{block} argument restricts the search to symbols visible
|
|
in that @var{block}. The @var{block} argument must be a
|
|
@code{gdb.Block} object. If omitted, the block for the current frame
|
|
is used. The optional @var{domain} argument restricts
|
|
the search to the domain type. The @var{domain} argument must be a
|
|
domain constant defined in the @code{gdb} module and described later
|
|
in this chapter.
|
|
|
|
The result is a tuple of two elements.
|
|
The first element is a @code{gdb.Symbol} object or @code{None} if the symbol
|
|
is not found.
|
|
If the symbol is found, the second element is @code{True} if the symbol
|
|
is a field of a method's object (e.g., @code{this} in C@t{++}),
|
|
otherwise it is @code{False}.
|
|
If the symbol is not found, the second element is @code{False}.
|
|
@end defun
|
|
|
|
@findex gdb.lookup_global_symbol
|
|
@defun gdb.lookup_global_symbol (name @r{[}, domain@r{]})
|
|
This function searches for a global symbol by name.
|
|
The search scope can be restricted to by the domain argument.
|
|
|
|
@var{name} is the name of the symbol. It must be a string.
|
|
The optional @var{domain} argument restricts the search to the domain type.
|
|
The @var{domain} argument must be a domain constant defined in the @code{gdb}
|
|
module and described later in this chapter.
|
|
|
|
The result is a @code{gdb.Symbol} object or @code{None} if the symbol
|
|
is not found.
|
|
@end defun
|
|
|
|
A @code{gdb.Symbol} object has the following attributes:
|
|
|
|
@table @code
|
|
@defvar Symbol.type
|
|
The type of the symbol or @code{None} if no type is recorded.
|
|
This attribute is represented as a @code{gdb.Type} object.
|
|
@xref{Types In Python}. This attribute is not writable.
|
|
@end defvar
|
|
|
|
@defvar Symbol.symtab
|
|
The symbol table in which the symbol appears. This attribute is
|
|
represented as a @code{gdb.Symtab} object. @xref{Symbol Tables In
|
|
Python}. This attribute is not writable.
|
|
@end defvar
|
|
|
|
@defvar Symbol.line
|
|
The line number in the source code at which the symbol was defined.
|
|
This is an integer.
|
|
@end defvar
|
|
|
|
@defvar Symbol.name
|
|
The name of the symbol as a string. This attribute is not writable.
|
|
@end defvar
|
|
|
|
@defvar Symbol.linkage_name
|
|
The name of the symbol, as used by the linker (i.e., may be mangled).
|
|
This attribute is not writable.
|
|
@end defvar
|
|
|
|
@defvar Symbol.print_name
|
|
The name of the symbol in a form suitable for output. This is either
|
|
@code{name} or @code{linkage_name}, depending on whether the user
|
|
asked @value{GDBN} to display demangled or mangled names.
|
|
@end defvar
|
|
|
|
@defvar Symbol.addr_class
|
|
The address class of the symbol. This classifies how to find the value
|
|
of a symbol. Each address class is a constant defined in the
|
|
@code{gdb} module and described later in this chapter.
|
|
@end defvar
|
|
|
|
@defvar Symbol.needs_frame
|
|
This is @code{True} if evaluating this symbol's value requires a frame
|
|
(@pxref{Frames In Python}) and @code{False} otherwise. Typically,
|
|
local variables will require a frame, but other symbols will not.
|
|
@end defvar
|
|
|
|
@defvar Symbol.is_argument
|
|
@code{True} if the symbol is an argument of a function.
|
|
@end defvar
|
|
|
|
@defvar Symbol.is_constant
|
|
@code{True} if the symbol is a constant.
|
|
@end defvar
|
|
|
|
@defvar Symbol.is_function
|
|
@code{True} if the symbol is a function or a method.
|
|
@end defvar
|
|
|
|
@defvar Symbol.is_variable
|
|
@code{True} if the symbol is a variable.
|
|
@end defvar
|
|
@end table
|
|
|
|
A @code{gdb.Symbol} object has the following methods:
|
|
|
|
@table @code
|
|
@defun Symbol.is_valid ()
|
|
Returns @code{True} if the @code{gdb.Symbol} object is valid,
|
|
@code{False} if not. A @code{gdb.Symbol} object can become invalid if
|
|
the symbol it refers to does not exist in @value{GDBN} any longer.
|
|
All other @code{gdb.Symbol} methods will throw an exception if it is
|
|
invalid at the time the method is called.
|
|
@end defun
|
|
|
|
@defun Symbol.value (@r{[}frame@r{]})
|
|
Compute the value of the symbol, as a @code{gdb.Value}. For
|
|
functions, this computes the address of the function, cast to the
|
|
appropriate type. If the symbol requires a frame in order to compute
|
|
its value, then @var{frame} must be given. If @var{frame} is not
|
|
given, or if @var{frame} is invalid, then this method will throw an
|
|
exception.
|
|
@end defun
|
|
@end table
|
|
|
|
The available domain categories in @code{gdb.Symbol} are represented
|
|
as constants in the @code{gdb} module:
|
|
|
|
@table @code
|
|
@findex SYMBOL_UNDEF_DOMAIN
|
|
@findex gdb.SYMBOL_UNDEF_DOMAIN
|
|
@item gdb.SYMBOL_UNDEF_DOMAIN
|
|
This is used when a domain has not been discovered or none of the
|
|
following domains apply. This usually indicates an error either
|
|
in the symbol information or in @value{GDBN}'s handling of symbols.
|
|
@findex SYMBOL_VAR_DOMAIN
|
|
@findex gdb.SYMBOL_VAR_DOMAIN
|
|
@item gdb.SYMBOL_VAR_DOMAIN
|
|
This domain contains variables, function names, typedef names and enum
|
|
type values.
|
|
@findex SYMBOL_STRUCT_DOMAIN
|
|
@findex gdb.SYMBOL_STRUCT_DOMAIN
|
|
@item gdb.SYMBOL_STRUCT_DOMAIN
|
|
This domain holds struct, union and enum type names.
|
|
@findex SYMBOL_LABEL_DOMAIN
|
|
@findex gdb.SYMBOL_LABEL_DOMAIN
|
|
@item gdb.SYMBOL_LABEL_DOMAIN
|
|
This domain contains names of labels (for gotos).
|
|
@findex SYMBOL_VARIABLES_DOMAIN
|
|
@findex gdb.SYMBOL_VARIABLES_DOMAIN
|
|
@item gdb.SYMBOL_VARIABLES_DOMAIN
|
|
This domain holds a subset of the @code{SYMBOLS_VAR_DOMAIN}; it
|
|
contains everything minus functions and types.
|
|
@findex SYMBOL_FUNCTIONS_DOMAIN
|
|
@findex gdb.SYMBOL_FUNCTIONS_DOMAIN
|
|
@item gdb.SYMBOL_FUNCTION_DOMAIN
|
|
This domain contains all functions.
|
|
@findex SYMBOL_TYPES_DOMAIN
|
|
@findex gdb.SYMBOL_TYPES_DOMAIN
|
|
@item gdb.SYMBOL_TYPES_DOMAIN
|
|
This domain contains all types.
|
|
@end table
|
|
|
|
The available address class categories in @code{gdb.Symbol} are represented
|
|
as constants in the @code{gdb} module:
|
|
|
|
@table @code
|
|
@findex SYMBOL_LOC_UNDEF
|
|
@findex gdb.SYMBOL_LOC_UNDEF
|
|
@item gdb.SYMBOL_LOC_UNDEF
|
|
If this is returned by address class, it indicates an error either in
|
|
the symbol information or in @value{GDBN}'s handling of symbols.
|
|
@findex SYMBOL_LOC_CONST
|
|
@findex gdb.SYMBOL_LOC_CONST
|
|
@item gdb.SYMBOL_LOC_CONST
|
|
Value is constant int.
|
|
@findex SYMBOL_LOC_STATIC
|
|
@findex gdb.SYMBOL_LOC_STATIC
|
|
@item gdb.SYMBOL_LOC_STATIC
|
|
Value is at a fixed address.
|
|
@findex SYMBOL_LOC_REGISTER
|
|
@findex gdb.SYMBOL_LOC_REGISTER
|
|
@item gdb.SYMBOL_LOC_REGISTER
|
|
Value is in a register.
|
|
@findex SYMBOL_LOC_ARG
|
|
@findex gdb.SYMBOL_LOC_ARG
|
|
@item gdb.SYMBOL_LOC_ARG
|
|
Value is an argument. This value is at the offset stored within the
|
|
symbol inside the frame's argument list.
|
|
@findex SYMBOL_LOC_REF_ARG
|
|
@findex gdb.SYMBOL_LOC_REF_ARG
|
|
@item gdb.SYMBOL_LOC_REF_ARG
|
|
Value address is stored in the frame's argument list. Just like
|
|
@code{LOC_ARG} except that the value's address is stored at the
|
|
offset, not the value itself.
|
|
@findex SYMBOL_LOC_REGPARM_ADDR
|
|
@findex gdb.SYMBOL_LOC_REGPARM_ADDR
|
|
@item gdb.SYMBOL_LOC_REGPARM_ADDR
|
|
Value is a specified register. Just like @code{LOC_REGISTER} except
|
|
the register holds the address of the argument instead of the argument
|
|
itself.
|
|
@findex SYMBOL_LOC_LOCAL
|
|
@findex gdb.SYMBOL_LOC_LOCAL
|
|
@item gdb.SYMBOL_LOC_LOCAL
|
|
Value is a local variable.
|
|
@findex SYMBOL_LOC_TYPEDEF
|
|
@findex gdb.SYMBOL_LOC_TYPEDEF
|
|
@item gdb.SYMBOL_LOC_TYPEDEF
|
|
Value not used. Symbols in the domain @code{SYMBOL_STRUCT_DOMAIN} all
|
|
have this class.
|
|
@findex SYMBOL_LOC_BLOCK
|
|
@findex gdb.SYMBOL_LOC_BLOCK
|
|
@item gdb.SYMBOL_LOC_BLOCK
|
|
Value is a block.
|
|
@findex SYMBOL_LOC_CONST_BYTES
|
|
@findex gdb.SYMBOL_LOC_CONST_BYTES
|
|
@item gdb.SYMBOL_LOC_CONST_BYTES
|
|
Value is a byte-sequence.
|
|
@findex SYMBOL_LOC_UNRESOLVED
|
|
@findex gdb.SYMBOL_LOC_UNRESOLVED
|
|
@item gdb.SYMBOL_LOC_UNRESOLVED
|
|
Value is at a fixed address, but the address of the variable has to be
|
|
determined from the minimal symbol table whenever the variable is
|
|
referenced.
|
|
@findex SYMBOL_LOC_OPTIMIZED_OUT
|
|
@findex gdb.SYMBOL_LOC_OPTIMIZED_OUT
|
|
@item gdb.SYMBOL_LOC_OPTIMIZED_OUT
|
|
The value does not actually exist in the program.
|
|
@findex SYMBOL_LOC_COMPUTED
|
|
@findex gdb.SYMBOL_LOC_COMPUTED
|
|
@item gdb.SYMBOL_LOC_COMPUTED
|
|
The value's address is a computed location.
|
|
@end table
|
|
|
|
@node Symbol Tables In Python
|
|
@subsubsection Symbol table representation in Python.
|
|
|
|
@cindex symbol tables in python
|
|
@tindex gdb.Symtab
|
|
@tindex gdb.Symtab_and_line
|
|
|
|
Access to symbol table data maintained by @value{GDBN} on the inferior
|
|
is exposed to Python via two objects: @code{gdb.Symtab_and_line} and
|
|
@code{gdb.Symtab}. Symbol table and line data for a frame is returned
|
|
from the @code{find_sal} method in @code{gdb.Frame} object.
|
|
@xref{Frames In Python}.
|
|
|
|
For more information on @value{GDBN}'s symbol table management, see
|
|
@ref{Symbols, ,Examining the Symbol Table}, for more information.
|
|
|
|
A @code{gdb.Symtab_and_line} object has the following attributes:
|
|
|
|
@table @code
|
|
@defvar Symtab_and_line.symtab
|
|
The symbol table object (@code{gdb.Symtab}) for this frame.
|
|
This attribute is not writable.
|
|
@end defvar
|
|
|
|
@defvar Symtab_and_line.pc
|
|
Indicates the start of the address range occupied by code for the
|
|
current source line. This attribute is not writable.
|
|
@end defvar
|
|
|
|
@defvar Symtab_and_line.last
|
|
Indicates the end of the address range occupied by code for the current
|
|
source line. This attribute is not writable.
|
|
@end defvar
|
|
|
|
@defvar Symtab_and_line.line
|
|
Indicates the current line number for this object. This
|
|
attribute is not writable.
|
|
@end defvar
|
|
@end table
|
|
|
|
A @code{gdb.Symtab_and_line} object has the following methods:
|
|
|
|
@table @code
|
|
@defun Symtab_and_line.is_valid ()
|
|
Returns @code{True} if the @code{gdb.Symtab_and_line} object is valid,
|
|
@code{False} if not. A @code{gdb.Symtab_and_line} object can become
|
|
invalid if the Symbol table and line object it refers to does not
|
|
exist in @value{GDBN} any longer. All other
|
|
@code{gdb.Symtab_and_line} methods will throw an exception if it is
|
|
invalid at the time the method is called.
|
|
@end defun
|
|
@end table
|
|
|
|
A @code{gdb.Symtab} object has the following attributes:
|
|
|
|
@table @code
|
|
@defvar Symtab.filename
|
|
The symbol table's source filename. This attribute is not writable.
|
|
@end defvar
|
|
|
|
@defvar Symtab.objfile
|
|
The symbol table's backing object file. @xref{Objfiles In Python}.
|
|
This attribute is not writable.
|
|
@end defvar
|
|
@end table
|
|
|
|
A @code{gdb.Symtab} object has the following methods:
|
|
|
|
@table @code
|
|
@defun Symtab.is_valid ()
|
|
Returns @code{True} if the @code{gdb.Symtab} object is valid,
|
|
@code{False} if not. A @code{gdb.Symtab} object can become invalid if
|
|
the symbol table it refers to does not exist in @value{GDBN} any
|
|
longer. All other @code{gdb.Symtab} methods will throw an exception
|
|
if it is invalid at the time the method is called.
|
|
@end defun
|
|
|
|
@defun Symtab.fullname ()
|
|
Return the symbol table's source absolute file name.
|
|
@end defun
|
|
|
|
@defun Symtab.global_block ()
|
|
Return the global block of the underlying symbol table.
|
|
@xref{Blocks In Python}.
|
|
@end defun
|
|
|
|
@defun Symtab.static_block ()
|
|
Return the static block of the underlying symbol table.
|
|
@xref{Blocks In Python}.
|
|
@end defun
|
|
@end table
|
|
|
|
@node Breakpoints In Python
|
|
@subsubsection Manipulating breakpoints using Python
|
|
|
|
@cindex breakpoints in python
|
|
@tindex gdb.Breakpoint
|
|
|
|
Python code can manipulate breakpoints via the @code{gdb.Breakpoint}
|
|
class.
|
|
|
|
@defun Breakpoint.__init__ (spec @r{[}, type @r{[}, wp_class @r{[},internal@r{]]]})
|
|
Create a new breakpoint. @var{spec} is a string naming the
|
|
location of the breakpoint, or an expression that defines a
|
|
watchpoint. The contents can be any location recognized by the
|
|
@code{break} command, or in the case of a watchpoint, by the @code{watch}
|
|
command. The optional @var{type} denotes the breakpoint to create
|
|
from the types defined later in this chapter. This argument can be
|
|
either: @code{gdb.BP_BREAKPOINT} or @code{gdb.BP_WATCHPOINT}. @var{type}
|
|
defaults to @code{gdb.BP_BREAKPOINT}. The optional @var{internal} argument
|
|
allows the breakpoint to become invisible to the user. The breakpoint
|
|
will neither be reported when created, nor will it be listed in the
|
|
output from @code{info breakpoints} (but will be listed with the
|
|
@code{maint info breakpoints} command). The optional @var{wp_class}
|
|
argument defines the class of watchpoint to create, if @var{type} is
|
|
@code{gdb.BP_WATCHPOINT}. If a watchpoint class is not provided, it is
|
|
assumed to be a @code{gdb.WP_WRITE} class.
|
|
@end defun
|
|
|
|
@defun Breakpoint.stop (self)
|
|
The @code{gdb.Breakpoint} class can be sub-classed and, in
|
|
particular, you may choose to implement the @code{stop} method.
|
|
If this method is defined as a sub-class of @code{gdb.Breakpoint},
|
|
it will be called when the inferior reaches any location of a
|
|
breakpoint which instantiates that sub-class. If the method returns
|
|
@code{True}, the inferior will be stopped at the location of the
|
|
breakpoint, otherwise the inferior will continue.
|
|
|
|
If there are multiple breakpoints at the same location with a
|
|
@code{stop} method, each one will be called regardless of the
|
|
return status of the previous. This ensures that all @code{stop}
|
|
methods have a chance to execute at that location. In this scenario
|
|
if one of the methods returns @code{True} but the others return
|
|
@code{False}, the inferior will still be stopped.
|
|
|
|
You should not alter the execution state of the inferior (i.e.@:, step,
|
|
next, etc.), alter the current frame context (i.e.@:, change the current
|
|
active frame), or alter, add or delete any breakpoint. As a general
|
|
rule, you should not alter any data within @value{GDBN} or the inferior
|
|
at this time.
|
|
|
|
Example @code{stop} implementation:
|
|
|
|
@smallexample
|
|
class MyBreakpoint (gdb.Breakpoint):
|
|
def stop (self):
|
|
inf_val = gdb.parse_and_eval("foo")
|
|
if inf_val == 3:
|
|
return True
|
|
return False
|
|
@end smallexample
|
|
@end defun
|
|
|
|
The available watchpoint types represented by constants are defined in the
|
|
@code{gdb} module:
|
|
|
|
@table @code
|
|
@findex WP_READ
|
|
@findex gdb.WP_READ
|
|
@item gdb.WP_READ
|
|
Read only watchpoint.
|
|
|
|
@findex WP_WRITE
|
|
@findex gdb.WP_WRITE
|
|
@item gdb.WP_WRITE
|
|
Write only watchpoint.
|
|
|
|
@findex WP_ACCESS
|
|
@findex gdb.WP_ACCESS
|
|
@item gdb.WP_ACCESS
|
|
Read/Write watchpoint.
|
|
@end table
|
|
|
|
@defun Breakpoint.is_valid ()
|
|
Return @code{True} if this @code{Breakpoint} object is valid,
|
|
@code{False} otherwise. A @code{Breakpoint} object can become invalid
|
|
if the user deletes the breakpoint. In this case, the object still
|
|
exists, but the underlying breakpoint does not. In the cases of
|
|
watchpoint scope, the watchpoint remains valid even if execution of the
|
|
inferior leaves the scope of that watchpoint.
|
|
@end defun
|
|
|
|
@defun Breakpoint.delete
|
|
Permanently deletes the @value{GDBN} breakpoint. This also
|
|
invalidates the Python @code{Breakpoint} object. Any further access
|
|
to this object's attributes or methods will raise an error.
|
|
@end defun
|
|
|
|
@defvar Breakpoint.enabled
|
|
This attribute is @code{True} if the breakpoint is enabled, and
|
|
@code{False} otherwise. This attribute is writable.
|
|
@end defvar
|
|
|
|
@defvar Breakpoint.silent
|
|
This attribute is @code{True} if the breakpoint is silent, and
|
|
@code{False} otherwise. This attribute is writable.
|
|
|
|
Note that a breakpoint can also be silent if it has commands and the
|
|
first command is @code{silent}. This is not reported by the
|
|
@code{silent} attribute.
|
|
@end defvar
|
|
|
|
@defvar Breakpoint.thread
|
|
If the breakpoint is thread-specific, this attribute holds the thread
|
|
id. If the breakpoint is not thread-specific, this attribute is
|
|
@code{None}. This attribute is writable.
|
|
@end defvar
|
|
|
|
@defvar Breakpoint.task
|
|
If the breakpoint is Ada task-specific, this attribute holds the Ada task
|
|
id. If the breakpoint is not task-specific (or the underlying
|
|
language is not Ada), this attribute is @code{None}. This attribute
|
|
is writable.
|
|
@end defvar
|
|
|
|
@defvar Breakpoint.ignore_count
|
|
This attribute holds the ignore count for the breakpoint, an integer.
|
|
This attribute is writable.
|
|
@end defvar
|
|
|
|
@defvar Breakpoint.number
|
|
This attribute holds the breakpoint's number --- the identifier used by
|
|
the user to manipulate the breakpoint. This attribute is not writable.
|
|
@end defvar
|
|
|
|
@defvar Breakpoint.type
|
|
This attribute holds the breakpoint's type --- the identifier used to
|
|
determine the actual breakpoint type or use-case. This attribute is not
|
|
writable.
|
|
@end defvar
|
|
|
|
@defvar Breakpoint.visible
|
|
This attribute tells whether the breakpoint is visible to the user
|
|
when set, or when the @samp{info breakpoints} command is run. This
|
|
attribute is not writable.
|
|
@end defvar
|
|
|
|
The available types are represented by constants defined in the @code{gdb}
|
|
module:
|
|
|
|
@table @code
|
|
@findex BP_BREAKPOINT
|
|
@findex gdb.BP_BREAKPOINT
|
|
@item gdb.BP_BREAKPOINT
|
|
Normal code breakpoint.
|
|
|
|
@findex BP_WATCHPOINT
|
|
@findex gdb.BP_WATCHPOINT
|
|
@item gdb.BP_WATCHPOINT
|
|
Watchpoint breakpoint.
|
|
|
|
@findex BP_HARDWARE_WATCHPOINT
|
|
@findex gdb.BP_HARDWARE_WATCHPOINT
|
|
@item gdb.BP_HARDWARE_WATCHPOINT
|
|
Hardware assisted watchpoint.
|
|
|
|
@findex BP_READ_WATCHPOINT
|
|
@findex gdb.BP_READ_WATCHPOINT
|
|
@item gdb.BP_READ_WATCHPOINT
|
|
Hardware assisted read watchpoint.
|
|
|
|
@findex BP_ACCESS_WATCHPOINT
|
|
@findex gdb.BP_ACCESS_WATCHPOINT
|
|
@item gdb.BP_ACCESS_WATCHPOINT
|
|
Hardware assisted access watchpoint.
|
|
@end table
|
|
|
|
@defvar Breakpoint.hit_count
|
|
This attribute holds the hit count for the breakpoint, an integer.
|
|
This attribute is writable, but currently it can only be set to zero.
|
|
@end defvar
|
|
|
|
@defvar Breakpoint.location
|
|
This attribute holds the location of the breakpoint, as specified by
|
|
the user. It is a string. If the breakpoint does not have a location
|
|
(that is, it is a watchpoint) the attribute's value is @code{None}. This
|
|
attribute is not writable.
|
|
@end defvar
|
|
|
|
@defvar Breakpoint.expression
|
|
This attribute holds a breakpoint expression, as specified by
|
|
the user. It is a string. If the breakpoint does not have an
|
|
expression (the breakpoint is not a watchpoint) the attribute's value
|
|
is @code{None}. This attribute is not writable.
|
|
@end defvar
|
|
|
|
@defvar Breakpoint.condition
|
|
This attribute holds the condition of the breakpoint, as specified by
|
|
the user. It is a string. If there is no condition, this attribute's
|
|
value is @code{None}. This attribute is writable.
|
|
@end defvar
|
|
|
|
@defvar Breakpoint.commands
|
|
This attribute holds the commands attached to the breakpoint. If
|
|
there are commands, this attribute's value is a string holding all the
|
|
commands, separated by newlines. If there are no commands, this
|
|
attribute is @code{None}. This attribute is not writable.
|
|
@end defvar
|
|
|
|
@node Finish Breakpoints in Python
|
|
@subsubsection Finish Breakpoints
|
|
|
|
@cindex python finish breakpoints
|
|
@tindex gdb.FinishBreakpoint
|
|
|
|
A finish breakpoint is a temporary breakpoint set at the return address of
|
|
a frame, based on the @code{finish} command. @code{gdb.FinishBreakpoint}
|
|
extends @code{gdb.Breakpoint}. The underlying breakpoint will be disabled
|
|
and deleted when the execution will run out of the breakpoint scope (i.e.@:
|
|
@code{Breakpoint.stop} or @code{FinishBreakpoint.out_of_scope} triggered).
|
|
Finish breakpoints are thread specific and must be create with the right
|
|
thread selected.
|
|
|
|
@defun FinishBreakpoint.__init__ (@r{[}frame@r{]} @r{[}, internal@r{]})
|
|
Create a finish breakpoint at the return address of the @code{gdb.Frame}
|
|
object @var{frame}. If @var{frame} is not provided, this defaults to the
|
|
newest frame. The optional @var{internal} argument allows the breakpoint to
|
|
become invisible to the user. @xref{Breakpoints In Python}, for further
|
|
details about this argument.
|
|
@end defun
|
|
|
|
@defun FinishBreakpoint.out_of_scope (self)
|
|
In some circumstances (e.g.@: @code{longjmp}, C@t{++} exceptions, @value{GDBN}
|
|
@code{return} command, @dots{}), a function may not properly terminate, and
|
|
thus never hit the finish breakpoint. When @value{GDBN} notices such a
|
|
situation, the @code{out_of_scope} callback will be triggered.
|
|
|
|
You may want to sub-class @code{gdb.FinishBreakpoint} and override this
|
|
method:
|
|
|
|
@smallexample
|
|
class MyFinishBreakpoint (gdb.FinishBreakpoint)
|
|
def stop (self):
|
|
print "normal finish"
|
|
return True
|
|
|
|
def out_of_scope ():
|
|
print "abnormal finish"
|
|
@end smallexample
|
|
@end defun
|
|
|
|
@defvar FinishBreakpoint.return_value
|
|
When @value{GDBN} is stopped at a finish breakpoint and the frame
|
|
used to build the @code{gdb.FinishBreakpoint} object had debug symbols, this
|
|
attribute will contain a @code{gdb.Value} object corresponding to the return
|
|
value of the function. The value will be @code{None} if the function return
|
|
type is @code{void} or if the return value was not computable. This attribute
|
|
is not writable.
|
|
@end defvar
|
|
|
|
@node Lazy Strings In Python
|
|
@subsubsection Python representation of lazy strings.
|
|
|
|
@cindex lazy strings in python
|
|
@tindex gdb.LazyString
|
|
|
|
A @dfn{lazy string} is a string whose contents is not retrieved or
|
|
encoded until it is needed.
|
|
|
|
A @code{gdb.LazyString} is represented in @value{GDBN} as an
|
|
@code{address} that points to a region of memory, an @code{encoding}
|
|
that will be used to encode that region of memory, and a @code{length}
|
|
to delimit the region of memory that represents the string. The
|
|
difference between a @code{gdb.LazyString} and a string wrapped within
|
|
a @code{gdb.Value} is that a @code{gdb.LazyString} will be treated
|
|
differently by @value{GDBN} when printing. A @code{gdb.LazyString} is
|
|
retrieved and encoded during printing, while a @code{gdb.Value}
|
|
wrapping a string is immediately retrieved and encoded on creation.
|
|
|
|
A @code{gdb.LazyString} object has the following functions:
|
|
|
|
@defun LazyString.value ()
|
|
Convert the @code{gdb.LazyString} to a @code{gdb.Value}. This value
|
|
will point to the string in memory, but will lose all the delayed
|
|
retrieval, encoding and handling that @value{GDBN} applies to a
|
|
@code{gdb.LazyString}.
|
|
@end defun
|
|
|
|
@defvar LazyString.address
|
|
This attribute holds the address of the string. This attribute is not
|
|
writable.
|
|
@end defvar
|
|
|
|
@defvar LazyString.length
|
|
This attribute holds the length of the string in characters. If the
|
|
length is -1, then the string will be fetched and encoded up to the
|
|
first null of appropriate width. This attribute is not writable.
|
|
@end defvar
|
|
|
|
@defvar LazyString.encoding
|
|
This attribute holds the encoding that will be applied to the string
|
|
when the string is printed by @value{GDBN}. If the encoding is not
|
|
set, or contains an empty string, then @value{GDBN} will select the
|
|
most appropriate encoding when the string is printed. This attribute
|
|
is not writable.
|
|
@end defvar
|
|
|
|
@defvar LazyString.type
|
|
This attribute holds the type that is represented by the lazy string's
|
|
type. For a lazy string this will always be a pointer type. To
|
|
resolve this to the lazy string's character type, use the type's
|
|
@code{target} method. @xref{Types In Python}. This attribute is not
|
|
writable.
|
|
@end defvar
|
|
|
|
@node Python Auto-loading
|
|
@subsection Python Auto-loading
|
|
@cindex Python auto-loading
|
|
|
|
When a new object file is read (for example, due to the @code{file}
|
|
command, or because the inferior has loaded a shared library),
|
|
@value{GDBN} will look for Python support scripts in several ways:
|
|
@file{@var{objfile}-gdb.py} (@pxref{objfile-gdb.py file})
|
|
and @code{.debug_gdb_scripts} section
|
|
(@pxref{dotdebug_gdb_scripts section}).
|
|
|
|
The auto-loading feature is useful for supplying application-specific
|
|
debugging commands and scripts.
|
|
|
|
Auto-loading can be enabled or disabled,
|
|
and the list of auto-loaded scripts can be printed.
|
|
|
|
@table @code
|
|
@anchor{set auto-load python-scripts}
|
|
@kindex set auto-load python-scripts
|
|
@item set auto-load python-scripts [on|off]
|
|
Enable or disable the auto-loading of Python scripts.
|
|
|
|
@anchor{show auto-load python-scripts}
|
|
@kindex show auto-load python-scripts
|
|
@item show auto-load python-scripts
|
|
Show whether auto-loading of Python scripts is enabled or disabled.
|
|
|
|
@anchor{info auto-load python-scripts}
|
|
@kindex info auto-load python-scripts
|
|
@cindex print list of auto-loaded Python scripts
|
|
@item info auto-load python-scripts [@var{regexp}]
|
|
Print the list of all Python scripts that @value{GDBN} auto-loaded.
|
|
|
|
Also printed is the list of Python scripts that were mentioned in
|
|
the @code{.debug_gdb_scripts} section and were not found
|
|
(@pxref{dotdebug_gdb_scripts section}).
|
|
This is useful because their names are not printed when @value{GDBN}
|
|
tries to load them and fails. There may be many of them, and printing
|
|
an error message for each one is problematic.
|
|
|
|
If @var{regexp} is supplied only Python scripts with matching names are printed.
|
|
|
|
Example:
|
|
|
|
@smallexample
|
|
(gdb) info auto-load python-scripts
|
|
Loaded Script
|
|
Yes py-section-script.py
|
|
full name: /tmp/py-section-script.py
|
|
No my-foo-pretty-printers.py
|
|
@end smallexample
|
|
@end table
|
|
|
|
When reading an auto-loaded file, @value{GDBN} sets the
|
|
@dfn{current objfile}. This is available via the @code{gdb.current_objfile}
|
|
function (@pxref{Objfiles In Python}). This can be useful for
|
|
registering objfile-specific pretty-printers.
|
|
|
|
@menu
|
|
* objfile-gdb.py file:: The @file{@var{objfile}-gdb.py} file
|
|
* dotdebug_gdb_scripts section:: The @code{.debug_gdb_scripts} section
|
|
* Which flavor to choose?::
|
|
@end menu
|
|
|
|
@node objfile-gdb.py file
|
|
@subsubsection The @file{@var{objfile}-gdb.py} file
|
|
@cindex @file{@var{objfile}-gdb.py}
|
|
|
|
When a new object file is read, @value{GDBN} looks for
|
|
a file named @file{@var{objfile}-gdb.py} (we call it @var{script-name} below),
|
|
where @var{objfile} is the object file's real name, formed by ensuring
|
|
that the file name is absolute, following all symlinks, and resolving
|
|
@code{.} and @code{..} components. If this file exists and is
|
|
readable, @value{GDBN} will evaluate it as a Python script.
|
|
|
|
If this file does not exist, then @value{GDBN} will look for
|
|
@var{script-name} file in all of the directories as specified below.
|
|
|
|
Note that loading of this script file also requires accordingly configured
|
|
@code{auto-load safe-path} (@pxref{Auto-loading safe path}).
|
|
|
|
@table @code
|
|
@anchor{set auto-load scripts-directory}
|
|
@kindex set auto-load scripts-directory
|
|
@item set auto-load scripts-directory @r{[}@var{directories}@r{]}
|
|
Control @value{GDBN} auto-loaded scripts location. Multiple directory entries
|
|
may be delimited by the host platform path separator in use
|
|
(@samp{:} on Unix, @samp{;} on MS-Windows and MS-DOS).
|
|
|
|
Each entry here needs to be covered also by the security setting
|
|
@code{set auto-load safe-path} (@pxref{set auto-load safe-path}).
|
|
|
|
@anchor{with-auto-load-dir}
|
|
This variable defaults to @file{$debugdir:$datadir/auto-load}. The default
|
|
@code{set auto-load safe-path} value can be also overriden by @value{GDBN}
|
|
configuration option @option{--with-auto-load-dir}.
|
|
|
|
Any reference to @file{$debugdir} will get replaced by
|
|
@var{debug-file-directory} value (@pxref{Separate Debug Files}) and any
|
|
reference to @file{$datadir} will get replaced by @var{data-directory} which is
|
|
determined at @value{GDBN} startup (@pxref{Data Files}). @file{$debugdir} and
|
|
@file{$datadir} must be placed as a directory component --- either alone or
|
|
delimited by @file{/} or @file{\} directory separators, depending on the host
|
|
platform.
|
|
|
|
The list of directories uses path separator (@samp{:} on GNU and Unix
|
|
systems, @samp{;} on MS-Windows and MS-DOS) to separate directories, similarly
|
|
to the @env{PATH} environment variable.
|
|
|
|
@anchor{show auto-load scripts-directory}
|
|
@kindex show auto-load scripts-directory
|
|
@item show auto-load scripts-directory
|
|
Show @value{GDBN} auto-loaded scripts location.
|
|
@end table
|
|
|
|
@value{GDBN} does not track which files it has already auto-loaded this way.
|
|
@value{GDBN} will load the associated script every time the corresponding
|
|
@var{objfile} is opened.
|
|
So your @file{-gdb.py} file should be careful to avoid errors if it
|
|
is evaluated more than once.
|
|
|
|
@node dotdebug_gdb_scripts section
|
|
@subsubsection The @code{.debug_gdb_scripts} section
|
|
@cindex @code{.debug_gdb_scripts} section
|
|
|
|
For systems using file formats like ELF and COFF,
|
|
when @value{GDBN} loads a new object file
|
|
it will look for a special section named @samp{.debug_gdb_scripts}.
|
|
If this section exists, its contents is a list of names of scripts to load.
|
|
|
|
@value{GDBN} will look for each specified script file first in the
|
|
current directory and then along the source search path
|
|
(@pxref{Source Path, ,Specifying Source Directories}),
|
|
except that @file{$cdir} is not searched, since the compilation
|
|
directory is not relevant to scripts.
|
|
|
|
Entries can be placed in section @code{.debug_gdb_scripts} with,
|
|
for example, this GCC macro:
|
|
|
|
@example
|
|
/* Note: The "MS" section flags are to remove duplicates. */
|
|
#define DEFINE_GDB_SCRIPT(script_name) \
|
|
asm("\
|
|
.pushsection \".debug_gdb_scripts\", \"MS\",@@progbits,1\n\
|
|
.byte 1\n\
|
|
.asciz \"" script_name "\"\n\
|
|
.popsection \n\
|
|
");
|
|
@end example
|
|
|
|
@noindent
|
|
Then one can reference the macro in a header or source file like this:
|
|
|
|
@example
|
|
DEFINE_GDB_SCRIPT ("my-app-scripts.py")
|
|
@end example
|
|
|
|
The script name may include directories if desired.
|
|
|
|
Note that loading of this script file also requires accordingly configured
|
|
@code{auto-load safe-path} (@pxref{Auto-loading safe path}).
|
|
|
|
If the macro is put in a header, any application or library
|
|
using this header will get a reference to the specified script.
|
|
|
|
@node Which flavor to choose?
|
|
@subsubsection Which flavor to choose?
|
|
|
|
Given the multiple ways of auto-loading Python scripts, it might not always
|
|
be clear which one to choose. This section provides some guidance.
|
|
|
|
Benefits of the @file{-gdb.py} way:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
Can be used with file formats that don't support multiple sections.
|
|
|
|
@item
|
|
Ease of finding scripts for public libraries.
|
|
|
|
Scripts specified in the @code{.debug_gdb_scripts} section are searched for
|
|
in the source search path.
|
|
For publicly installed libraries, e.g., @file{libstdc++}, there typically
|
|
isn't a source directory in which to find the script.
|
|
|
|
@item
|
|
Doesn't require source code additions.
|
|
@end itemize
|
|
|
|
Benefits of the @code{.debug_gdb_scripts} way:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
Works with static linking.
|
|
|
|
Scripts for libraries done the @file{-gdb.py} way require an objfile to
|
|
trigger their loading. When an application is statically linked the only
|
|
objfile available is the executable, and it is cumbersome to attach all the
|
|
scripts from all the input libraries to the executable's @file{-gdb.py} script.
|
|
|
|
@item
|
|
Works with classes that are entirely inlined.
|
|
|
|
Some classes can be entirely inlined, and thus there may not be an associated
|
|
shared library to attach a @file{-gdb.py} script to.
|
|
|
|
@item
|
|
Scripts needn't be copied out of the source tree.
|
|
|
|
In some circumstances, apps can be built out of large collections of internal
|
|
libraries, and the build infrastructure necessary to install the
|
|
@file{-gdb.py} scripts in a place where @value{GDBN} can find them is
|
|
cumbersome. It may be easier to specify the scripts in the
|
|
@code{.debug_gdb_scripts} section as relative paths, and add a path to the
|
|
top of the source tree to the source search path.
|
|
@end itemize
|
|
|
|
@node Python modules
|
|
@subsection Python modules
|
|
@cindex python modules
|
|
|
|
@value{GDBN} comes with several modules to assist writing Python code.
|
|
|
|
@menu
|
|
* gdb.printing:: Building and registering pretty-printers.
|
|
* gdb.types:: Utilities for working with types.
|
|
* gdb.prompt:: Utilities for prompt value substitution.
|
|
@end menu
|
|
|
|
@node gdb.printing
|
|
@subsubsection gdb.printing
|
|
@cindex gdb.printing
|
|
|
|
This module provides a collection of utilities for working with
|
|
pretty-printers.
|
|
|
|
@table @code
|
|
@item PrettyPrinter (@var{name}, @var{subprinters}=None)
|
|
This class specifies the API that makes @samp{info pretty-printer},
|
|
@samp{enable pretty-printer} and @samp{disable pretty-printer} work.
|
|
Pretty-printers should generally inherit from this class.
|
|
|
|
@item SubPrettyPrinter (@var{name})
|
|
For printers that handle multiple types, this class specifies the
|
|
corresponding API for the subprinters.
|
|
|
|
@item RegexpCollectionPrettyPrinter (@var{name})
|
|
Utility class for handling multiple printers, all recognized via
|
|
regular expressions.
|
|
@xref{Writing a Pretty-Printer}, for an example.
|
|
|
|
@item FlagEnumerationPrinter (@var{name})
|
|
A pretty-printer which handles printing of @code{enum} values. Unlike
|
|
@value{GDBN}'s built-in @code{enum} printing, this printer attempts to
|
|
work properly when there is some overlap between the enumeration
|
|
constants. @var{name} is the name of the printer and also the name of
|
|
the @code{enum} type to look up.
|
|
|
|
@item register_pretty_printer (@var{obj}, @var{printer}, @var{replace}=False)
|
|
Register @var{printer} with the pretty-printer list of @var{obj}.
|
|
If @var{replace} is @code{True} then any existing copy of the printer
|
|
is replaced. Otherwise a @code{RuntimeError} exception is raised
|
|
if a printer with the same name already exists.
|
|
@end table
|
|
|
|
@node gdb.types
|
|
@subsubsection gdb.types
|
|
@cindex gdb.types
|
|
|
|
This module provides a collection of utilities for working with
|
|
@code{gdb.Types} objects.
|
|
|
|
@table @code
|
|
@item get_basic_type (@var{type})
|
|
Return @var{type} with const and volatile qualifiers stripped,
|
|
and with typedefs and C@t{++} references converted to the underlying type.
|
|
|
|
C@t{++} example:
|
|
|
|
@smallexample
|
|
typedef const int const_int;
|
|
const_int foo (3);
|
|
const_int& foo_ref (foo);
|
|
int main () @{ return 0; @}
|
|
@end smallexample
|
|
|
|
Then in gdb:
|
|
|
|
@smallexample
|
|
(gdb) start
|
|
(gdb) python import gdb.types
|
|
(gdb) python foo_ref = gdb.parse_and_eval("foo_ref")
|
|
(gdb) python print gdb.types.get_basic_type(foo_ref.type)
|
|
int
|
|
@end smallexample
|
|
|
|
@item has_field (@var{type}, @var{field})
|
|
Return @code{True} if @var{type}, assumed to be a type with fields
|
|
(e.g., a structure or union), has field @var{field}.
|
|
|
|
@item make_enum_dict (@var{enum_type})
|
|
Return a Python @code{dictionary} type produced from @var{enum_type}.
|
|
|
|
@item deep_items (@var{type})
|
|
Returns a Python iterator similar to the standard
|
|
@code{gdb.Type.iteritems} method, except that the iterator returned
|
|
by @code{deep_items} will recursively traverse anonymous struct or
|
|
union fields. For example:
|
|
|
|
@smallexample
|
|
struct A
|
|
@{
|
|
int a;
|
|
union @{
|
|
int b0;
|
|
int b1;
|
|
@};
|
|
@};
|
|
@end smallexample
|
|
|
|
@noindent
|
|
Then in @value{GDBN}:
|
|
@smallexample
|
|
(@value{GDBP}) python import gdb.types
|
|
(@value{GDBP}) python struct_a = gdb.lookup_type("struct A")
|
|
(@value{GDBP}) python print struct_a.keys ()
|
|
@{['a', '']@}
|
|
(@value{GDBP}) python print [k for k,v in gdb.types.deep_items(struct_a)]
|
|
@{['a', 'b0', 'b1']@}
|
|
@end smallexample
|
|
|
|
@end table
|
|
|
|
@node gdb.prompt
|
|
@subsubsection gdb.prompt
|
|
@cindex gdb.prompt
|
|
|
|
This module provides a method for prompt value-substitution.
|
|
|
|
@table @code
|
|
@item substitute_prompt (@var{string})
|
|
Return @var{string} with escape sequences substituted by values. Some
|
|
escape sequences take arguments. You can specify arguments inside
|
|
``@{@}'' immediately following the escape sequence.
|
|
|
|
The escape sequences you can pass to this function are:
|
|
|
|
@table @code
|
|
@item \\
|
|
Substitute a backslash.
|
|
@item \e
|
|
Substitute an ESC character.
|
|
@item \f
|
|
Substitute the selected frame; an argument names a frame parameter.
|
|
@item \n
|
|
Substitute a newline.
|
|
@item \p
|
|
Substitute a parameter's value; the argument names the parameter.
|
|
@item \r
|
|
Substitute a carriage return.
|
|
@item \t
|
|
Substitute the selected thread; an argument names a thread parameter.
|
|
@item \v
|
|
Substitute the version of GDB.
|
|
@item \w
|
|
Substitute the current working directory.
|
|
@item \[
|
|
Begin a sequence of non-printing characters. These sequences are
|
|
typically used with the ESC character, and are not counted in the string
|
|
length. Example: ``\[\e[0;34m\](gdb)\[\e[0m\]'' will return a
|
|
blue-colored ``(gdb)'' prompt where the length is five.
|
|
@item \]
|
|
End a sequence of non-printing characters.
|
|
@end table
|
|
|
|
For example:
|
|
|
|
@smallexample
|
|
substitute_prompt (``frame: \f,
|
|
print arguments: \p@{print frame-arguments@}'')
|
|
@end smallexample
|
|
|
|
@exdent will return the string:
|
|
|
|
@smallexample
|
|
"frame: main, print arguments: scalars"
|
|
@end smallexample
|
|
@end table
|
|
|
|
@node Aliases
|
|
@section Creating new spellings of existing commands
|
|
@cindex aliases for commands
|
|
|
|
It is often useful to define alternate spellings of existing commands.
|
|
For example, if a new @value{GDBN} command defined in Python has
|
|
a long name to type, it is handy to have an abbreviated version of it
|
|
that involves less typing.
|
|
|
|
@value{GDBN} itself uses aliases. For example @samp{s} is an alias
|
|
of the @samp{step} command even though it is otherwise an ambiguous
|
|
abbreviation of other commands like @samp{set} and @samp{show}.
|
|
|
|
Aliases are also used to provide shortened or more common versions
|
|
of multi-word commands. For example, @value{GDBN} provides the
|
|
@samp{tty} alias of the @samp{set inferior-tty} command.
|
|
|
|
You can define a new alias with the @samp{alias} command.
|
|
|
|
@table @code
|
|
|
|
@kindex alias
|
|
@item alias [-a] [--] @var{ALIAS} = @var{COMMAND}
|
|
|
|
@end table
|
|
|
|
@var{ALIAS} specifies the name of the new alias.
|
|
Each word of @var{ALIAS} must consist of letters, numbers, dashes and
|
|
underscores.
|
|
|
|
@var{COMMAND} specifies the name of an existing command
|
|
that is being aliased.
|
|
|
|
The @samp{-a} option specifies that the new alias is an abbreviation
|
|
of the command. Abbreviations are not shown in command
|
|
lists displayed by the @samp{help} command.
|
|
|
|
The @samp{--} option specifies the end of options,
|
|
and is useful when @var{ALIAS} begins with a dash.
|
|
|
|
Here is a simple example showing how to make an abbreviation
|
|
of a command so that there is less to type.
|
|
Suppose you were tired of typing @samp{disas}, the current
|
|
shortest unambiguous abbreviation of the @samp{disassemble} command
|
|
and you wanted an even shorter version named @samp{di}.
|
|
The following will accomplish this.
|
|
|
|
@smallexample
|
|
(gdb) alias -a di = disas
|
|
@end smallexample
|
|
|
|
Note that aliases are different from user-defined commands.
|
|
With a user-defined command, you also need to write documentation
|
|
for it with the @samp{document} command.
|
|
An alias automatically picks up the documentation of the existing command.
|
|
|
|
Here is an example where we make @samp{elms} an abbreviation of
|
|
@samp{elements} in the @samp{set print elements} command.
|
|
This is to show that you can make an abbreviation of any part
|
|
of a command.
|
|
|
|
@smallexample
|
|
(gdb) alias -a set print elms = set print elements
|
|
(gdb) alias -a show print elms = show print elements
|
|
(gdb) set p elms 20
|
|
(gdb) show p elms
|
|
Limit on string chars or array elements to print is 200.
|
|
@end smallexample
|
|
|
|
Note that if you are defining an alias of a @samp{set} command,
|
|
and you want to have an alias for the corresponding @samp{show}
|
|
command, then you need to define the latter separately.
|
|
|
|
Unambiguously abbreviated commands are allowed in @var{COMMAND} and
|
|
@var{ALIAS}, just as they are normally.
|
|
|
|
@smallexample
|
|
(gdb) alias -a set pr elms = set p ele
|
|
@end smallexample
|
|
|
|
Finally, here is an example showing the creation of a one word
|
|
alias for a more complex command.
|
|
This creates alias @samp{spe} of the command @samp{set print elements}.
|
|
|
|
@smallexample
|
|
(gdb) alias spe = set print elements
|
|
(gdb) spe 20
|
|
@end smallexample
|
|
|
|
@node Interpreters
|
|
@chapter Command Interpreters
|
|
@cindex command interpreters
|
|
|
|
@value{GDBN} supports multiple command interpreters, and some command
|
|
infrastructure to allow users or user interface writers to switch
|
|
between interpreters or run commands in other interpreters.
|
|
|
|
@value{GDBN} currently supports two command interpreters, the console
|
|
interpreter (sometimes called the command-line interpreter or @sc{cli})
|
|
and the machine interface interpreter (or @sc{gdb/mi}). This manual
|
|
describes both of these interfaces in great detail.
|
|
|
|
By default, @value{GDBN} will start with the console interpreter.
|
|
However, the user may choose to start @value{GDBN} with another
|
|
interpreter by specifying the @option{-i} or @option{--interpreter}
|
|
startup options. Defined interpreters include:
|
|
|
|
@table @code
|
|
@item console
|
|
@cindex console interpreter
|
|
The traditional console or command-line interpreter. This is the most often
|
|
used interpreter with @value{GDBN}. With no interpreter specified at runtime,
|
|
@value{GDBN} will use this interpreter.
|
|
|
|
@item mi
|
|
@cindex mi interpreter
|
|
The newest @sc{gdb/mi} interface (currently @code{mi2}). Used primarily
|
|
by programs wishing to use @value{GDBN} as a backend for a debugger GUI
|
|
or an IDE. For more information, see @ref{GDB/MI, ,The @sc{gdb/mi}
|
|
Interface}.
|
|
|
|
@item mi2
|
|
@cindex mi2 interpreter
|
|
The current @sc{gdb/mi} interface.
|
|
|
|
@item mi1
|
|
@cindex mi1 interpreter
|
|
The @sc{gdb/mi} interface included in @value{GDBN} 5.1, 5.2, and 5.3.
|
|
|
|
@end table
|
|
|
|
@cindex invoke another interpreter
|
|
The interpreter being used by @value{GDBN} may not be dynamically
|
|
switched at runtime. Although possible, this could lead to a very
|
|
precarious situation. Consider an IDE using @sc{gdb/mi}. If a user
|
|
enters the command "interpreter-set console" in a console view,
|
|
@value{GDBN} would switch to using the console interpreter, rendering
|
|
the IDE inoperable!
|
|
|
|
@kindex interpreter-exec
|
|
Although you may only choose a single interpreter at startup, you may execute
|
|
commands in any interpreter from the current interpreter using the appropriate
|
|
command. If you are running the console interpreter, simply use the
|
|
@code{interpreter-exec} command:
|
|
|
|
@smallexample
|
|
interpreter-exec mi "-data-list-register-names"
|
|
@end smallexample
|
|
|
|
@sc{gdb/mi} has a similar command, although it is only available in versions of
|
|
@value{GDBN} which support @sc{gdb/mi} version 2 (or greater).
|
|
|
|
@node TUI
|
|
@chapter @value{GDBN} Text User Interface
|
|
@cindex TUI
|
|
@cindex Text User Interface
|
|
|
|
@menu
|
|
* TUI Overview:: TUI overview
|
|
* TUI Keys:: TUI key bindings
|
|
* TUI Single Key Mode:: TUI single key mode
|
|
* TUI Commands:: TUI-specific commands
|
|
* TUI Configuration:: TUI configuration variables
|
|
@end menu
|
|
|
|
The @value{GDBN} Text User Interface (TUI) is a terminal
|
|
interface which uses the @code{curses} library to show the source
|
|
file, the assembly output, the program registers and @value{GDBN}
|
|
commands in separate text windows. The TUI mode is supported only
|
|
on platforms where a suitable version of the @code{curses} library
|
|
is available.
|
|
|
|
The TUI mode is enabled by default when you invoke @value{GDBN} as
|
|
@samp{@value{GDBP} -tui}.
|
|
You can also switch in and out of TUI mode while @value{GDBN} runs by
|
|
using various TUI commands and key bindings, such as @kbd{C-x C-a}.
|
|
@xref{TUI Keys, ,TUI Key Bindings}.
|
|
|
|
@node TUI Overview
|
|
@section TUI Overview
|
|
|
|
In TUI mode, @value{GDBN} can display several text windows:
|
|
|
|
@table @emph
|
|
@item command
|
|
This window is the @value{GDBN} command window with the @value{GDBN}
|
|
prompt and the @value{GDBN} output. The @value{GDBN} input is still
|
|
managed using readline.
|
|
|
|
@item source
|
|
The source window shows the source file of the program. The current
|
|
line and active breakpoints are displayed in this window.
|
|
|
|
@item assembly
|
|
The assembly window shows the disassembly output of the program.
|
|
|
|
@item register
|
|
This window shows the processor registers. Registers are highlighted
|
|
when their values change.
|
|
@end table
|
|
|
|
The source and assembly windows show the current program position
|
|
by highlighting the current line and marking it with a @samp{>} marker.
|
|
Breakpoints are indicated with two markers. The first marker
|
|
indicates the breakpoint type:
|
|
|
|
@table @code
|
|
@item B
|
|
Breakpoint which was hit at least once.
|
|
|
|
@item b
|
|
Breakpoint which was never hit.
|
|
|
|
@item H
|
|
Hardware breakpoint which was hit at least once.
|
|
|
|
@item h
|
|
Hardware breakpoint which was never hit.
|
|
@end table
|
|
|
|
The second marker indicates whether the breakpoint is enabled or not:
|
|
|
|
@table @code
|
|
@item +
|
|
Breakpoint is enabled.
|
|
|
|
@item -
|
|
Breakpoint is disabled.
|
|
@end table
|
|
|
|
The source, assembly and register windows are updated when the current
|
|
thread changes, when the frame changes, or when the program counter
|
|
changes.
|
|
|
|
These windows are not all visible at the same time. The command
|
|
window is always visible. The others can be arranged in several
|
|
layouts:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
source only,
|
|
|
|
@item
|
|
assembly only,
|
|
|
|
@item
|
|
source and assembly,
|
|
|
|
@item
|
|
source and registers, or
|
|
|
|
@item
|
|
assembly and registers.
|
|
@end itemize
|
|
|
|
A status line above the command window shows the following information:
|
|
|
|
@table @emph
|
|
@item target
|
|
Indicates the current @value{GDBN} target.
|
|
(@pxref{Targets, ,Specifying a Debugging Target}).
|
|
|
|
@item process
|
|
Gives the current process or thread number.
|
|
When no process is being debugged, this field is set to @code{No process}.
|
|
|
|
@item function
|
|
Gives the current function name for the selected frame.
|
|
The name is demangled if demangling is turned on (@pxref{Print Settings}).
|
|
When there is no symbol corresponding to the current program counter,
|
|
the string @code{??} is displayed.
|
|
|
|
@item line
|
|
Indicates the current line number for the selected frame.
|
|
When the current line number is not known, the string @code{??} is displayed.
|
|
|
|
@item pc
|
|
Indicates the current program counter address.
|
|
@end table
|
|
|
|
@node TUI Keys
|
|
@section TUI Key Bindings
|
|
@cindex TUI key bindings
|
|
|
|
The TUI installs several key bindings in the readline keymaps
|
|
@ifset SYSTEM_READLINE
|
|
(@pxref{Command Line Editing, , , rluserman, GNU Readline Library}).
|
|
@end ifset
|
|
@ifclear SYSTEM_READLINE
|
|
(@pxref{Command Line Editing}).
|
|
@end ifclear
|
|
The following key bindings are installed for both TUI mode and the
|
|
@value{GDBN} standard mode.
|
|
|
|
@table @kbd
|
|
@kindex C-x C-a
|
|
@item C-x C-a
|
|
@kindex C-x a
|
|
@itemx C-x a
|
|
@kindex C-x A
|
|
@itemx C-x A
|
|
Enter or leave the TUI mode. When leaving the TUI mode,
|
|
the curses window management stops and @value{GDBN} operates using
|
|
its standard mode, writing on the terminal directly. When reentering
|
|
the TUI mode, control is given back to the curses windows.
|
|
The screen is then refreshed.
|
|
|
|
@kindex C-x 1
|
|
@item C-x 1
|
|
Use a TUI layout with only one window. The layout will
|
|
either be @samp{source} or @samp{assembly}. When the TUI mode
|
|
is not active, it will switch to the TUI mode.
|
|
|
|
Think of this key binding as the Emacs @kbd{C-x 1} binding.
|
|
|
|
@kindex C-x 2
|
|
@item C-x 2
|
|
Use a TUI layout with at least two windows. When the current
|
|
layout already has two windows, the next layout with two windows is used.
|
|
When a new layout is chosen, one window will always be common to the
|
|
previous layout and the new one.
|
|
|
|
Think of it as the Emacs @kbd{C-x 2} binding.
|
|
|
|
@kindex C-x o
|
|
@item C-x o
|
|
Change the active window. The TUI associates several key bindings
|
|
(like scrolling and arrow keys) with the active window. This command
|
|
gives the focus to the next TUI window.
|
|
|
|
Think of it as the Emacs @kbd{C-x o} binding.
|
|
|
|
@kindex C-x s
|
|
@item C-x s
|
|
Switch in and out of the TUI SingleKey mode that binds single
|
|
keys to @value{GDBN} commands (@pxref{TUI Single Key Mode}).
|
|
@end table
|
|
|
|
The following key bindings only work in the TUI mode:
|
|
|
|
@table @asis
|
|
@kindex PgUp
|
|
@item @key{PgUp}
|
|
Scroll the active window one page up.
|
|
|
|
@kindex PgDn
|
|
@item @key{PgDn}
|
|
Scroll the active window one page down.
|
|
|
|
@kindex Up
|
|
@item @key{Up}
|
|
Scroll the active window one line up.
|
|
|
|
@kindex Down
|
|
@item @key{Down}
|
|
Scroll the active window one line down.
|
|
|
|
@kindex Left
|
|
@item @key{Left}
|
|
Scroll the active window one column left.
|
|
|
|
@kindex Right
|
|
@item @key{Right}
|
|
Scroll the active window one column right.
|
|
|
|
@kindex C-L
|
|
@item @kbd{C-L}
|
|
Refresh the screen.
|
|
@end table
|
|
|
|
Because the arrow keys scroll the active window in the TUI mode, they
|
|
are not available for their normal use by readline unless the command
|
|
window has the focus. When another window is active, you must use
|
|
other readline key bindings such as @kbd{C-p}, @kbd{C-n}, @kbd{C-b}
|
|
and @kbd{C-f} to control the command window.
|
|
|
|
@node TUI Single Key Mode
|
|
@section TUI Single Key Mode
|
|
@cindex TUI single key mode
|
|
|
|
The TUI also provides a @dfn{SingleKey} mode, which binds several
|
|
frequently used @value{GDBN} commands to single keys. Type @kbd{C-x s} to
|
|
switch into this mode, where the following key bindings are used:
|
|
|
|
@table @kbd
|
|
@kindex c @r{(SingleKey TUI key)}
|
|
@item c
|
|
continue
|
|
|
|
@kindex d @r{(SingleKey TUI key)}
|
|
@item d
|
|
down
|
|
|
|
@kindex f @r{(SingleKey TUI key)}
|
|
@item f
|
|
finish
|
|
|
|
@kindex n @r{(SingleKey TUI key)}
|
|
@item n
|
|
next
|
|
|
|
@kindex q @r{(SingleKey TUI key)}
|
|
@item q
|
|
exit the SingleKey mode.
|
|
|
|
@kindex r @r{(SingleKey TUI key)}
|
|
@item r
|
|
run
|
|
|
|
@kindex s @r{(SingleKey TUI key)}
|
|
@item s
|
|
step
|
|
|
|
@kindex u @r{(SingleKey TUI key)}
|
|
@item u
|
|
up
|
|
|
|
@kindex v @r{(SingleKey TUI key)}
|
|
@item v
|
|
info locals
|
|
|
|
@kindex w @r{(SingleKey TUI key)}
|
|
@item w
|
|
where
|
|
@end table
|
|
|
|
Other keys temporarily switch to the @value{GDBN} command prompt.
|
|
The key that was pressed is inserted in the editing buffer so that
|
|
it is possible to type most @value{GDBN} commands without interaction
|
|
with the TUI SingleKey mode. Once the command is entered the TUI
|
|
SingleKey mode is restored. The only way to permanently leave
|
|
this mode is by typing @kbd{q} or @kbd{C-x s}.
|
|
|
|
|
|
@node TUI Commands
|
|
@section TUI-specific Commands
|
|
@cindex TUI commands
|
|
|
|
The TUI has specific commands to control the text windows.
|
|
These commands are always available, even when @value{GDBN} is not in
|
|
the TUI mode. When @value{GDBN} is in the standard mode, most
|
|
of these commands will automatically switch to the TUI mode.
|
|
|
|
Note that if @value{GDBN}'s @code{stdout} is not connected to a
|
|
terminal, or @value{GDBN} has been started with the machine interface
|
|
interpreter (@pxref{GDB/MI, ,The @sc{gdb/mi} Interface}), most of
|
|
these commands will fail with an error, because it would not be
|
|
possible or desirable to enable curses window management.
|
|
|
|
@table @code
|
|
@item info win
|
|
@kindex info win
|
|
List and give the size of all displayed windows.
|
|
|
|
@item layout next
|
|
@kindex layout
|
|
Display the next layout.
|
|
|
|
@item layout prev
|
|
Display the previous layout.
|
|
|
|
@item layout src
|
|
Display the source window only.
|
|
|
|
@item layout asm
|
|
Display the assembly window only.
|
|
|
|
@item layout split
|
|
Display the source and assembly window.
|
|
|
|
@item layout regs
|
|
Display the register window together with the source or assembly window.
|
|
|
|
@item focus next
|
|
@kindex focus
|
|
Make the next window active for scrolling.
|
|
|
|
@item focus prev
|
|
Make the previous window active for scrolling.
|
|
|
|
@item focus src
|
|
Make the source window active for scrolling.
|
|
|
|
@item focus asm
|
|
Make the assembly window active for scrolling.
|
|
|
|
@item focus regs
|
|
Make the register window active for scrolling.
|
|
|
|
@item focus cmd
|
|
Make the command window active for scrolling.
|
|
|
|
@item refresh
|
|
@kindex refresh
|
|
Refresh the screen. This is similar to typing @kbd{C-L}.
|
|
|
|
@item tui reg float
|
|
@kindex tui reg
|
|
Show the floating point registers in the register window.
|
|
|
|
@item tui reg general
|
|
Show the general registers in the register window.
|
|
|
|
@item tui reg next
|
|
Show the next register group. The list of register groups as well as
|
|
their order is target specific. The predefined register groups are the
|
|
following: @code{general}, @code{float}, @code{system}, @code{vector},
|
|
@code{all}, @code{save}, @code{restore}.
|
|
|
|
@item tui reg system
|
|
Show the system registers in the register window.
|
|
|
|
@item update
|
|
@kindex update
|
|
Update the source window and the current execution point.
|
|
|
|
@item winheight @var{name} +@var{count}
|
|
@itemx winheight @var{name} -@var{count}
|
|
@kindex winheight
|
|
Change the height of the window @var{name} by @var{count}
|
|
lines. Positive counts increase the height, while negative counts
|
|
decrease it.
|
|
|
|
@item tabset @var{nchars}
|
|
@kindex tabset
|
|
Set the width of tab stops to be @var{nchars} characters.
|
|
@end table
|
|
|
|
@node TUI Configuration
|
|
@section TUI Configuration Variables
|
|
@cindex TUI configuration variables
|
|
|
|
Several configuration variables control the appearance of TUI windows.
|
|
|
|
@table @code
|
|
@item set tui border-kind @var{kind}
|
|
@kindex set tui border-kind
|
|
Select the border appearance for the source, assembly and register windows.
|
|
The possible values are the following:
|
|
@table @code
|
|
@item space
|
|
Use a space character to draw the border.
|
|
|
|
@item ascii
|
|
Use @sc{ascii} characters @samp{+}, @samp{-} and @samp{|} to draw the border.
|
|
|
|
@item acs
|
|
Use the Alternate Character Set to draw the border. The border is
|
|
drawn using character line graphics if the terminal supports them.
|
|
@end table
|
|
|
|
@item set tui border-mode @var{mode}
|
|
@kindex set tui border-mode
|
|
@itemx set tui active-border-mode @var{mode}
|
|
@kindex set tui active-border-mode
|
|
Select the display attributes for the borders of the inactive windows
|
|
or the active window. The @var{mode} can be one of the following:
|
|
@table @code
|
|
@item normal
|
|
Use normal attributes to display the border.
|
|
|
|
@item standout
|
|
Use standout mode.
|
|
|
|
@item reverse
|
|
Use reverse video mode.
|
|
|
|
@item half
|
|
Use half bright mode.
|
|
|
|
@item half-standout
|
|
Use half bright and standout mode.
|
|
|
|
@item bold
|
|
Use extra bright or bold mode.
|
|
|
|
@item bold-standout
|
|
Use extra bright or bold and standout mode.
|
|
@end table
|
|
@end table
|
|
|
|
@node Emacs
|
|
@chapter Using @value{GDBN} under @sc{gnu} Emacs
|
|
|
|
@cindex Emacs
|
|
@cindex @sc{gnu} Emacs
|
|
A special interface allows you to use @sc{gnu} Emacs to view (and
|
|
edit) the source files for the program you are debugging with
|
|
@value{GDBN}.
|
|
|
|
To use this interface, use the command @kbd{M-x gdb} in Emacs. Give the
|
|
executable file you want to debug as an argument. This command starts
|
|
@value{GDBN} as a subprocess of Emacs, with input and output through a newly
|
|
created Emacs buffer.
|
|
@c (Do not use the @code{-tui} option to run @value{GDBN} from Emacs.)
|
|
|
|
Running @value{GDBN} under Emacs can be just like running @value{GDBN} normally except for two
|
|
things:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
All ``terminal'' input and output goes through an Emacs buffer, called
|
|
the GUD buffer.
|
|
|
|
This applies both to @value{GDBN} commands and their output, and to the input
|
|
and output done by the program you are debugging.
|
|
|
|
This is useful because it means that you can copy the text of previous
|
|
commands and input them again; you can even use parts of the output
|
|
in this way.
|
|
|
|
All the facilities of Emacs' Shell mode are available for interacting
|
|
with your program. In particular, you can send signals the usual
|
|
way---for example, @kbd{C-c C-c} for an interrupt, @kbd{C-c C-z} for a
|
|
stop.
|
|
|
|
@item
|
|
@value{GDBN} displays source code through Emacs.
|
|
|
|
Each time @value{GDBN} displays a stack frame, Emacs automatically finds the
|
|
source file for that frame and puts an arrow (@samp{=>}) at the
|
|
left margin of the current line. Emacs uses a separate buffer for
|
|
source display, and splits the screen to show both your @value{GDBN} session
|
|
and the source.
|
|
|
|
Explicit @value{GDBN} @code{list} or search commands still produce output as
|
|
usual, but you probably have no reason to use them from Emacs.
|
|
@end itemize
|
|
|
|
We call this @dfn{text command mode}. Emacs 22.1, and later, also uses
|
|
a graphical mode, enabled by default, which provides further buffers
|
|
that can control the execution and describe the state of your program.
|
|
@xref{GDB Graphical Interface,,, Emacs, The @sc{gnu} Emacs Manual}.
|
|
|
|
If you specify an absolute file name when prompted for the @kbd{M-x
|
|
gdb} argument, then Emacs sets your current working directory to where
|
|
your program resides. If you only specify the file name, then Emacs
|
|
sets your current working directory to the directory associated
|
|
with the previous buffer. In this case, @value{GDBN} may find your
|
|
program by searching your environment's @code{PATH} variable, but on
|
|
some operating systems it might not find the source. So, although the
|
|
@value{GDBN} input and output session proceeds normally, the auxiliary
|
|
buffer does not display the current source and line of execution.
|
|
|
|
The initial working directory of @value{GDBN} is printed on the top
|
|
line of the GUD buffer and this serves as a default for the commands
|
|
that specify files for @value{GDBN} to operate on. @xref{Files,
|
|
,Commands to Specify Files}.
|
|
|
|
By default, @kbd{M-x gdb} calls the program called @file{gdb}. If you
|
|
need to call @value{GDBN} by a different name (for example, if you
|
|
keep several configurations around, with different names) you can
|
|
customize the Emacs variable @code{gud-gdb-command-name} to run the
|
|
one you want.
|
|
|
|
In the GUD buffer, you can use these special Emacs commands in
|
|
addition to the standard Shell mode commands:
|
|
|
|
@table @kbd
|
|
@item C-h m
|
|
Describe the features of Emacs' GUD Mode.
|
|
|
|
@item C-c C-s
|
|
Execute to another source line, like the @value{GDBN} @code{step} command; also
|
|
update the display window to show the current file and location.
|
|
|
|
@item C-c C-n
|
|
Execute to next source line in this function, skipping all function
|
|
calls, like the @value{GDBN} @code{next} command. Then update the display window
|
|
to show the current file and location.
|
|
|
|
@item C-c C-i
|
|
Execute one instruction, like the @value{GDBN} @code{stepi} command; update
|
|
display window accordingly.
|
|
|
|
@item C-c C-f
|
|
Execute until exit from the selected stack frame, like the @value{GDBN}
|
|
@code{finish} command.
|
|
|
|
@item C-c C-r
|
|
Continue execution of your program, like the @value{GDBN} @code{continue}
|
|
command.
|
|
|
|
@item C-c <
|
|
Go up the number of frames indicated by the numeric argument
|
|
(@pxref{Arguments, , Numeric Arguments, Emacs, The @sc{gnu} Emacs Manual}),
|
|
like the @value{GDBN} @code{up} command.
|
|
|
|
@item C-c >
|
|
Go down the number of frames indicated by the numeric argument, like the
|
|
@value{GDBN} @code{down} command.
|
|
@end table
|
|
|
|
In any source file, the Emacs command @kbd{C-x @key{SPC}} (@code{gud-break})
|
|
tells @value{GDBN} to set a breakpoint on the source line point is on.
|
|
|
|
In text command mode, if you type @kbd{M-x speedbar}, Emacs displays a
|
|
separate frame which shows a backtrace when the GUD buffer is current.
|
|
Move point to any frame in the stack and type @key{RET} to make it
|
|
become the current frame and display the associated source in the
|
|
source buffer. Alternatively, click @kbd{Mouse-2} to make the
|
|
selected frame become the current one. In graphical mode, the
|
|
speedbar displays watch expressions.
|
|
|
|
If you accidentally delete the source-display buffer, an easy way to get
|
|
it back is to type the command @code{f} in the @value{GDBN} buffer, to
|
|
request a frame display; when you run under Emacs, this recreates
|
|
the source buffer if necessary to show you the context of the current
|
|
frame.
|
|
|
|
The source files displayed in Emacs are in ordinary Emacs buffers
|
|
which are visiting the source files in the usual way. You can edit
|
|
the files with these buffers if you wish; but keep in mind that @value{GDBN}
|
|
communicates with Emacs in terms of line numbers. If you add or
|
|
delete lines from the text, the line numbers that @value{GDBN} knows cease
|
|
to correspond properly with the code.
|
|
|
|
A more detailed description of Emacs' interaction with @value{GDBN} is
|
|
given in the Emacs manual (@pxref{Debuggers,,, Emacs, The @sc{gnu}
|
|
Emacs Manual}).
|
|
|
|
@c The following dropped because Epoch is nonstandard. Reactivate
|
|
@c if/when v19 does something similar. ---doc@cygnus.com 19dec1990
|
|
@ignore
|
|
@kindex Emacs Epoch environment
|
|
@kindex Epoch
|
|
@kindex inspect
|
|
|
|
Version 18 of @sc{gnu} Emacs has a built-in window system
|
|
called the @code{epoch}
|
|
environment. Users of this environment can use a new command,
|
|
@code{inspect} which performs identically to @code{print} except that
|
|
each value is printed in its own window.
|
|
@end ignore
|
|
|
|
|
|
@node GDB/MI
|
|
@chapter The @sc{gdb/mi} Interface
|
|
|
|
@unnumberedsec Function and Purpose
|
|
|
|
@cindex @sc{gdb/mi}, its purpose
|
|
@sc{gdb/mi} is a line based machine oriented text interface to
|
|
@value{GDBN} and is activated by specifying using the
|
|
@option{--interpreter} command line option (@pxref{Mode Options}). It
|
|
is specifically intended to support the development of systems which
|
|
use the debugger as just one small component of a larger system.
|
|
|
|
This chapter is a specification of the @sc{gdb/mi} interface. It is written
|
|
in the form of a reference manual.
|
|
|
|
Note that @sc{gdb/mi} is still under construction, so some of the
|
|
features described below are incomplete and subject to change
|
|
(@pxref{GDB/MI Development and Front Ends, , @sc{gdb/mi} Development and Front Ends}).
|
|
|
|
@unnumberedsec Notation and Terminology
|
|
|
|
@cindex notational conventions, for @sc{gdb/mi}
|
|
This chapter uses the following notation:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
@code{|} separates two alternatives.
|
|
|
|
@item
|
|
@code{[ @var{something} ]} indicates that @var{something} is optional:
|
|
it may or may not be given.
|
|
|
|
@item
|
|
@code{( @var{group} )*} means that @var{group} inside the parentheses
|
|
may repeat zero or more times.
|
|
|
|
@item
|
|
@code{( @var{group} )+} means that @var{group} inside the parentheses
|
|
may repeat one or more times.
|
|
|
|
@item
|
|
@code{"@var{string}"} means a literal @var{string}.
|
|
@end itemize
|
|
|
|
@ignore
|
|
@heading Dependencies
|
|
@end ignore
|
|
|
|
@menu
|
|
* GDB/MI General Design::
|
|
* GDB/MI Command Syntax::
|
|
* GDB/MI Compatibility with CLI::
|
|
* GDB/MI Development and Front Ends::
|
|
* GDB/MI Output Records::
|
|
* GDB/MI Simple Examples::
|
|
* GDB/MI Command Description Format::
|
|
* GDB/MI Breakpoint Commands::
|
|
* GDB/MI Program Context::
|
|
* GDB/MI Thread Commands::
|
|
* GDB/MI Ada Tasking Commands::
|
|
* GDB/MI Program Execution::
|
|
* GDB/MI Stack Manipulation::
|
|
* GDB/MI Variable Objects::
|
|
* GDB/MI Data Manipulation::
|
|
* GDB/MI Tracepoint Commands::
|
|
* GDB/MI Symbol Query::
|
|
* GDB/MI File Commands::
|
|
@ignore
|
|
* GDB/MI Kod Commands::
|
|
* GDB/MI Memory Overlay Commands::
|
|
* GDB/MI Signal Handling Commands::
|
|
@end ignore
|
|
* GDB/MI Target Manipulation::
|
|
* GDB/MI File Transfer Commands::
|
|
* GDB/MI Miscellaneous Commands::
|
|
@end menu
|
|
|
|
@c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
@node GDB/MI General Design
|
|
@section @sc{gdb/mi} General Design
|
|
@cindex GDB/MI General Design
|
|
|
|
Interaction of a @sc{GDB/MI} frontend with @value{GDBN} involves three
|
|
parts---commands sent to @value{GDBN}, responses to those commands
|
|
and notifications. Each command results in exactly one response,
|
|
indicating either successful completion of the command, or an error.
|
|
For the commands that do not resume the target, the response contains the
|
|
requested information. For the commands that resume the target, the
|
|
response only indicates whether the target was successfully resumed.
|
|
Notifications is the mechanism for reporting changes in the state of the
|
|
target, or in @value{GDBN} state, that cannot conveniently be associated with
|
|
a command and reported as part of that command response.
|
|
|
|
The important examples of notifications are:
|
|
@itemize @bullet
|
|
|
|
@item
|
|
Exec notifications. These are used to report changes in
|
|
target state---when a target is resumed, or stopped. It would not
|
|
be feasible to include this information in response of resuming
|
|
commands, because one resume commands can result in multiple events in
|
|
different threads. Also, quite some time may pass before any event
|
|
happens in the target, while a frontend needs to know whether the resuming
|
|
command itself was successfully executed.
|
|
|
|
@item
|
|
Console output, and status notifications. Console output
|
|
notifications are used to report output of CLI commands, as well as
|
|
diagnostics for other commands. Status notifications are used to
|
|
report the progress of a long-running operation. Naturally, including
|
|
this information in command response would mean no output is produced
|
|
until the command is finished, which is undesirable.
|
|
|
|
@item
|
|
General notifications. Commands may have various side effects on
|
|
the @value{GDBN} or target state beyond their official purpose. For example,
|
|
a command may change the selected thread. Although such changes can
|
|
be included in command response, using notification allows for more
|
|
orthogonal frontend design.
|
|
|
|
@end itemize
|
|
|
|
There's no guarantee that whenever an MI command reports an error,
|
|
@value{GDBN} or the target are in any specific state, and especially,
|
|
the state is not reverted to the state before the MI command was
|
|
processed. Therefore, whenever an MI command results in an error,
|
|
we recommend that the frontend refreshes all the information shown in
|
|
the user interface.
|
|
|
|
|
|
@menu
|
|
* Context management::
|
|
* Asynchronous and non-stop modes::
|
|
* Thread groups::
|
|
@end menu
|
|
|
|
@node Context management
|
|
@subsection Context management
|
|
|
|
In most cases when @value{GDBN} accesses the target, this access is
|
|
done in context of a specific thread and frame (@pxref{Frames}).
|
|
Often, even when accessing global data, the target requires that a thread
|
|
be specified. The CLI interface maintains the selected thread and frame,
|
|
and supplies them to target on each command. This is convenient,
|
|
because a command line user would not want to specify that information
|
|
explicitly on each command, and because user interacts with
|
|
@value{GDBN} via a single terminal, so no confusion is possible as
|
|
to what thread and frame are the current ones.
|
|
|
|
In the case of MI, the concept of selected thread and frame is less
|
|
useful. First, a frontend can easily remember this information
|
|
itself. Second, a graphical frontend can have more than one window,
|
|
each one used for debugging a different thread, and the frontend might
|
|
want to access additional threads for internal purposes. This
|
|
increases the risk that by relying on implicitly selected thread, the
|
|
frontend may be operating on a wrong one. Therefore, each MI command
|
|
should explicitly specify which thread and frame to operate on. To
|
|
make it possible, each MI command accepts the @samp{--thread} and
|
|
@samp{--frame} options, the value to each is @value{GDBN} identifier
|
|
for thread and frame to operate on.
|
|
|
|
Usually, each top-level window in a frontend allows the user to select
|
|
a thread and a frame, and remembers the user selection for further
|
|
operations. However, in some cases @value{GDBN} may suggest that the
|
|
current thread be changed. For example, when stopping on a breakpoint
|
|
it is reasonable to switch to the thread where breakpoint is hit. For
|
|
another example, if the user issues the CLI @samp{thread} command via
|
|
the frontend, it is desirable to change the frontend's selected thread to the
|
|
one specified by user. @value{GDBN} communicates the suggestion to
|
|
change current thread using the @samp{=thread-selected} notification.
|
|
No such notification is available for the selected frame at the moment.
|
|
|
|
Note that historically, MI shares the selected thread with CLI, so
|
|
frontends used the @code{-thread-select} to execute commands in the
|
|
right context. However, getting this to work right is cumbersome. The
|
|
simplest way is for frontend to emit @code{-thread-select} command
|
|
before every command. This doubles the number of commands that need
|
|
to be sent. The alternative approach is to suppress @code{-thread-select}
|
|
if the selected thread in @value{GDBN} is supposed to be identical to the
|
|
thread the frontend wants to operate on. However, getting this
|
|
optimization right can be tricky. In particular, if the frontend
|
|
sends several commands to @value{GDBN}, and one of the commands changes the
|
|
selected thread, then the behaviour of subsequent commands will
|
|
change. So, a frontend should either wait for response from such
|
|
problematic commands, or explicitly add @code{-thread-select} for
|
|
all subsequent commands. No frontend is known to do this exactly
|
|
right, so it is suggested to just always pass the @samp{--thread} and
|
|
@samp{--frame} options.
|
|
|
|
@node Asynchronous and non-stop modes
|
|
@subsection Asynchronous command execution and non-stop mode
|
|
|
|
On some targets, @value{GDBN} is capable of processing MI commands
|
|
even while the target is running. This is called @dfn{asynchronous
|
|
command execution} (@pxref{Background Execution}). The frontend may
|
|
specify a preferrence for asynchronous execution using the
|
|
@code{-gdb-set target-async 1} command, which should be emitted before
|
|
either running the executable or attaching to the target. After the
|
|
frontend has started the executable or attached to the target, it can
|
|
find if asynchronous execution is enabled using the
|
|
@code{-list-target-features} command.
|
|
|
|
Even if @value{GDBN} can accept a command while target is running,
|
|
many commands that access the target do not work when the target is
|
|
running. Therefore, asynchronous command execution is most useful
|
|
when combined with non-stop mode (@pxref{Non-Stop Mode}). Then,
|
|
it is possible to examine the state of one thread, while other threads
|
|
are running.
|
|
|
|
When a given thread is running, MI commands that try to access the
|
|
target in the context of that thread may not work, or may work only on
|
|
some targets. In particular, commands that try to operate on thread's
|
|
stack will not work, on any target. Commands that read memory, or
|
|
modify breakpoints, may work or not work, depending on the target. Note
|
|
that even commands that operate on global state, such as @code{print},
|
|
@code{set}, and breakpoint commands, still access the target in the
|
|
context of a specific thread, so frontend should try to find a
|
|
stopped thread and perform the operation on that thread (using the
|
|
@samp{--thread} option).
|
|
|
|
Which commands will work in the context of a running thread is
|
|
highly target dependent. However, the two commands
|
|
@code{-exec-interrupt}, to stop a thread, and @code{-thread-info},
|
|
to find the state of a thread, will always work.
|
|
|
|
@node Thread groups
|
|
@subsection Thread groups
|
|
@value{GDBN} may be used to debug several processes at the same time.
|
|
On some platfroms, @value{GDBN} may support debugging of several
|
|
hardware systems, each one having several cores with several different
|
|
processes running on each core. This section describes the MI
|
|
mechanism to support such debugging scenarios.
|
|
|
|
The key observation is that regardless of the structure of the
|
|
target, MI can have a global list of threads, because most commands that
|
|
accept the @samp{--thread} option do not need to know what process that
|
|
thread belongs to. Therefore, it is not necessary to introduce
|
|
neither additional @samp{--process} option, nor an notion of the
|
|
current process in the MI interface. The only strictly new feature
|
|
that is required is the ability to find how the threads are grouped
|
|
into processes.
|
|
|
|
To allow the user to discover such grouping, and to support arbitrary
|
|
hierarchy of machines/cores/processes, MI introduces the concept of a
|
|
@dfn{thread group}. Thread group is a collection of threads and other
|
|
thread groups. A thread group always has a string identifier, a type,
|
|
and may have additional attributes specific to the type. A new
|
|
command, @code{-list-thread-groups}, returns the list of top-level
|
|
thread groups, which correspond to processes that @value{GDBN} is
|
|
debugging at the moment. By passing an identifier of a thread group
|
|
to the @code{-list-thread-groups} command, it is possible to obtain
|
|
the members of specific thread group.
|
|
|
|
To allow the user to easily discover processes, and other objects, he
|
|
wishes to debug, a concept of @dfn{available thread group} is
|
|
introduced. Available thread group is an thread group that
|
|
@value{GDBN} is not debugging, but that can be attached to, using the
|
|
@code{-target-attach} command. The list of available top-level thread
|
|
groups can be obtained using @samp{-list-thread-groups --available}.
|
|
In general, the content of a thread group may be only retrieved only
|
|
after attaching to that thread group.
|
|
|
|
Thread groups are related to inferiors (@pxref{Inferiors and
|
|
Programs}). Each inferior corresponds to a thread group of a special
|
|
type @samp{process}, and some additional operations are permitted on
|
|
such thread groups.
|
|
|
|
@c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
@node GDB/MI Command Syntax
|
|
@section @sc{gdb/mi} Command Syntax
|
|
|
|
@menu
|
|
* GDB/MI Input Syntax::
|
|
* GDB/MI Output Syntax::
|
|
@end menu
|
|
|
|
@node GDB/MI Input Syntax
|
|
@subsection @sc{gdb/mi} Input Syntax
|
|
|
|
@cindex input syntax for @sc{gdb/mi}
|
|
@cindex @sc{gdb/mi}, input syntax
|
|
@table @code
|
|
@item @var{command} @expansion{}
|
|
@code{@var{cli-command} | @var{mi-command}}
|
|
|
|
@item @var{cli-command} @expansion{}
|
|
@code{[ @var{token} ] @var{cli-command} @var{nl}}, where
|
|
@var{cli-command} is any existing @value{GDBN} CLI command.
|
|
|
|
@item @var{mi-command} @expansion{}
|
|
@code{[ @var{token} ] "-" @var{operation} ( " " @var{option} )*
|
|
@code{[} " --" @code{]} ( " " @var{parameter} )* @var{nl}}
|
|
|
|
@item @var{token} @expansion{}
|
|
"any sequence of digits"
|
|
|
|
@item @var{option} @expansion{}
|
|
@code{"-" @var{parameter} [ " " @var{parameter} ]}
|
|
|
|
@item @var{parameter} @expansion{}
|
|
@code{@var{non-blank-sequence} | @var{c-string}}
|
|
|
|
@item @var{operation} @expansion{}
|
|
@emph{any of the operations described in this chapter}
|
|
|
|
@item @var{non-blank-sequence} @expansion{}
|
|
@emph{anything, provided it doesn't contain special characters such as
|
|
"-", @var{nl}, """ and of course " "}
|
|
|
|
@item @var{c-string} @expansion{}
|
|
@code{""" @var{seven-bit-iso-c-string-content} """}
|
|
|
|
@item @var{nl} @expansion{}
|
|
@code{CR | CR-LF}
|
|
@end table
|
|
|
|
@noindent
|
|
Notes:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
The CLI commands are still handled by the @sc{mi} interpreter; their
|
|
output is described below.
|
|
|
|
@item
|
|
The @code{@var{token}}, when present, is passed back when the command
|
|
finishes.
|
|
|
|
@item
|
|
Some @sc{mi} commands accept optional arguments as part of the parameter
|
|
list. Each option is identified by a leading @samp{-} (dash) and may be
|
|
followed by an optional argument parameter. Options occur first in the
|
|
parameter list and can be delimited from normal parameters using
|
|
@samp{--} (this is useful when some parameters begin with a dash).
|
|
@end itemize
|
|
|
|
Pragmatics:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
We want easy access to the existing CLI syntax (for debugging).
|
|
|
|
@item
|
|
We want it to be easy to spot a @sc{mi} operation.
|
|
@end itemize
|
|
|
|
@node GDB/MI Output Syntax
|
|
@subsection @sc{gdb/mi} Output Syntax
|
|
|
|
@cindex output syntax of @sc{gdb/mi}
|
|
@cindex @sc{gdb/mi}, output syntax
|
|
The output from @sc{gdb/mi} consists of zero or more out-of-band records
|
|
followed, optionally, by a single result record. This result record
|
|
is for the most recent command. The sequence of output records is
|
|
terminated by @samp{(gdb)}.
|
|
|
|
If an input command was prefixed with a @code{@var{token}} then the
|
|
corresponding output for that command will also be prefixed by that same
|
|
@var{token}.
|
|
|
|
@table @code
|
|
@item @var{output} @expansion{}
|
|
@code{( @var{out-of-band-record} )* [ @var{result-record} ] "(gdb)" @var{nl}}
|
|
|
|
@item @var{result-record} @expansion{}
|
|
@code{ [ @var{token} ] "^" @var{result-class} ( "," @var{result} )* @var{nl}}
|
|
|
|
@item @var{out-of-band-record} @expansion{}
|
|
@code{@var{async-record} | @var{stream-record}}
|
|
|
|
@item @var{async-record} @expansion{}
|
|
@code{@var{exec-async-output} | @var{status-async-output} | @var{notify-async-output}}
|
|
|
|
@item @var{exec-async-output} @expansion{}
|
|
@code{[ @var{token} ] "*" @var{async-output}}
|
|
|
|
@item @var{status-async-output} @expansion{}
|
|
@code{[ @var{token} ] "+" @var{async-output}}
|
|
|
|
@item @var{notify-async-output} @expansion{}
|
|
@code{[ @var{token} ] "=" @var{async-output}}
|
|
|
|
@item @var{async-output} @expansion{}
|
|
@code{@var{async-class} ( "," @var{result} )* @var{nl}}
|
|
|
|
@item @var{result-class} @expansion{}
|
|
@code{"done" | "running" | "connected" | "error" | "exit"}
|
|
|
|
@item @var{async-class} @expansion{}
|
|
@code{"stopped" | @var{others}} (where @var{others} will be added
|
|
depending on the needs---this is still in development).
|
|
|
|
@item @var{result} @expansion{}
|
|
@code{ @var{variable} "=" @var{value}}
|
|
|
|
@item @var{variable} @expansion{}
|
|
@code{ @var{string} }
|
|
|
|
@item @var{value} @expansion{}
|
|
@code{ @var{const} | @var{tuple} | @var{list} }
|
|
|
|
@item @var{const} @expansion{}
|
|
@code{@var{c-string}}
|
|
|
|
@item @var{tuple} @expansion{}
|
|
@code{ "@{@}" | "@{" @var{result} ( "," @var{result} )* "@}" }
|
|
|
|
@item @var{list} @expansion{}
|
|
@code{ "[]" | "[" @var{value} ( "," @var{value} )* "]" | "["
|
|
@var{result} ( "," @var{result} )* "]" }
|
|
|
|
@item @var{stream-record} @expansion{}
|
|
@code{@var{console-stream-output} | @var{target-stream-output} | @var{log-stream-output}}
|
|
|
|
@item @var{console-stream-output} @expansion{}
|
|
@code{"~" @var{c-string}}
|
|
|
|
@item @var{target-stream-output} @expansion{}
|
|
@code{"@@" @var{c-string}}
|
|
|
|
@item @var{log-stream-output} @expansion{}
|
|
@code{"&" @var{c-string}}
|
|
|
|
@item @var{nl} @expansion{}
|
|
@code{CR | CR-LF}
|
|
|
|
@item @var{token} @expansion{}
|
|
@emph{any sequence of digits}.
|
|
@end table
|
|
|
|
@noindent
|
|
Notes:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
All output sequences end in a single line containing a period.
|
|
|
|
@item
|
|
The @code{@var{token}} is from the corresponding request. Note that
|
|
for all async output, while the token is allowed by the grammar and
|
|
may be output by future versions of @value{GDBN} for select async
|
|
output messages, it is generally omitted. Frontends should treat
|
|
all async output as reporting general changes in the state of the
|
|
target and there should be no need to associate async output to any
|
|
prior command.
|
|
|
|
@item
|
|
@cindex status output in @sc{gdb/mi}
|
|
@var{status-async-output} contains on-going status information about the
|
|
progress of a slow operation. It can be discarded. All status output is
|
|
prefixed by @samp{+}.
|
|
|
|
@item
|
|
@cindex async output in @sc{gdb/mi}
|
|
@var{exec-async-output} contains asynchronous state change on the target
|
|
(stopped, started, disappeared). All async output is prefixed by
|
|
@samp{*}.
|
|
|
|
@item
|
|
@cindex notify output in @sc{gdb/mi}
|
|
@var{notify-async-output} contains supplementary information that the
|
|
client should handle (e.g., a new breakpoint information). All notify
|
|
output is prefixed by @samp{=}.
|
|
|
|
@item
|
|
@cindex console output in @sc{gdb/mi}
|
|
@var{console-stream-output} is output that should be displayed as is in the
|
|
console. It is the textual response to a CLI command. All the console
|
|
output is prefixed by @samp{~}.
|
|
|
|
@item
|
|
@cindex target output in @sc{gdb/mi}
|
|
@var{target-stream-output} is the output produced by the target program.
|
|
All the target output is prefixed by @samp{@@}.
|
|
|
|
@item
|
|
@cindex log output in @sc{gdb/mi}
|
|
@var{log-stream-output} is output text coming from @value{GDBN}'s internals, for
|
|
instance messages that should be displayed as part of an error log. All
|
|
the log output is prefixed by @samp{&}.
|
|
|
|
@item
|
|
@cindex list output in @sc{gdb/mi}
|
|
New @sc{gdb/mi} commands should only output @var{lists} containing
|
|
@var{values}.
|
|
|
|
|
|
@end itemize
|
|
|
|
@xref{GDB/MI Stream Records, , @sc{gdb/mi} Stream Records}, for more
|
|
details about the various output records.
|
|
|
|
@c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
@node GDB/MI Compatibility with CLI
|
|
@section @sc{gdb/mi} Compatibility with CLI
|
|
|
|
@cindex compatibility, @sc{gdb/mi} and CLI
|
|
@cindex @sc{gdb/mi}, compatibility with CLI
|
|
|
|
For the developers convenience CLI commands can be entered directly,
|
|
but there may be some unexpected behaviour. For example, commands
|
|
that query the user will behave as if the user replied yes, breakpoint
|
|
command lists are not executed and some CLI commands, such as
|
|
@code{if}, @code{when} and @code{define}, prompt for further input with
|
|
@samp{>}, which is not valid MI output.
|
|
|
|
This feature may be removed at some stage in the future and it is
|
|
recommended that front ends use the @code{-interpreter-exec} command
|
|
(@pxref{-interpreter-exec}).
|
|
|
|
@c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
@node GDB/MI Development and Front Ends
|
|
@section @sc{gdb/mi} Development and Front Ends
|
|
@cindex @sc{gdb/mi} development
|
|
|
|
The application which takes the MI output and presents the state of the
|
|
program being debugged to the user is called a @dfn{front end}.
|
|
|
|
Although @sc{gdb/mi} is still incomplete, it is currently being used
|
|
by a variety of front ends to @value{GDBN}. This makes it difficult
|
|
to introduce new functionality without breaking existing usage. This
|
|
section tries to minimize the problems by describing how the protocol
|
|
might change.
|
|
|
|
Some changes in MI need not break a carefully designed front end, and
|
|
for these the MI version will remain unchanged. The following is a
|
|
list of changes that may occur within one level, so front ends should
|
|
parse MI output in a way that can handle them:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
New MI commands may be added.
|
|
|
|
@item
|
|
New fields may be added to the output of any MI command.
|
|
|
|
@item
|
|
The range of values for fields with specified values, e.g.,
|
|
@code{in_scope} (@pxref{-var-update}) may be extended.
|
|
|
|
@c The format of field's content e.g type prefix, may change so parse it
|
|
@c at your own risk. Yes, in general?
|
|
|
|
@c The order of fields may change? Shouldn't really matter but it might
|
|
@c resolve inconsistencies.
|
|
@end itemize
|
|
|
|
If the changes are likely to break front ends, the MI version level
|
|
will be increased by one. This will allow the front end to parse the
|
|
output according to the MI version. Apart from mi0, new versions of
|
|
@value{GDBN} will not support old versions of MI and it will be the
|
|
responsibility of the front end to work with the new one.
|
|
|
|
@c Starting with mi3, add a new command -mi-version that prints the MI
|
|
@c version?
|
|
|
|
The best way to avoid unexpected changes in MI that might break your front
|
|
end is to make your project known to @value{GDBN} developers and
|
|
follow development on @email{gdb@@sourceware.org} and
|
|
@email{gdb-patches@@sourceware.org}.
|
|
@cindex mailing lists
|
|
|
|
@c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
@node GDB/MI Output Records
|
|
@section @sc{gdb/mi} Output Records
|
|
|
|
@menu
|
|
* GDB/MI Result Records::
|
|
* GDB/MI Stream Records::
|
|
* GDB/MI Async Records::
|
|
* GDB/MI Frame Information::
|
|
* GDB/MI Thread Information::
|
|
* GDB/MI Ada Exception Information::
|
|
@end menu
|
|
|
|
@node GDB/MI Result Records
|
|
@subsection @sc{gdb/mi} Result Records
|
|
|
|
@cindex result records in @sc{gdb/mi}
|
|
@cindex @sc{gdb/mi}, result records
|
|
In addition to a number of out-of-band notifications, the response to a
|
|
@sc{gdb/mi} command includes one of the following result indications:
|
|
|
|
@table @code
|
|
@findex ^done
|
|
@item "^done" [ "," @var{results} ]
|
|
The synchronous operation was successful, @code{@var{results}} are the return
|
|
values.
|
|
|
|
@item "^running"
|
|
@findex ^running
|
|
This result record is equivalent to @samp{^done}. Historically, it
|
|
was output instead of @samp{^done} if the command has resumed the
|
|
target. This behaviour is maintained for backward compatibility, but
|
|
all frontends should treat @samp{^done} and @samp{^running}
|
|
identically and rely on the @samp{*running} output record to determine
|
|
which threads are resumed.
|
|
|
|
@item "^connected"
|
|
@findex ^connected
|
|
@value{GDBN} has connected to a remote target.
|
|
|
|
@item "^error" "," @var{c-string}
|
|
@findex ^error
|
|
The operation failed. The @code{@var{c-string}} contains the corresponding
|
|
error message.
|
|
|
|
@item "^exit"
|
|
@findex ^exit
|
|
@value{GDBN} has terminated.
|
|
|
|
@end table
|
|
|
|
@node GDB/MI Stream Records
|
|
@subsection @sc{gdb/mi} Stream Records
|
|
|
|
@cindex @sc{gdb/mi}, stream records
|
|
@cindex stream records in @sc{gdb/mi}
|
|
@value{GDBN} internally maintains a number of output streams: the console, the
|
|
target, and the log. The output intended for each of these streams is
|
|
funneled through the @sc{gdb/mi} interface using @dfn{stream records}.
|
|
|
|
Each stream record begins with a unique @dfn{prefix character} which
|
|
identifies its stream (@pxref{GDB/MI Output Syntax, , @sc{gdb/mi} Output
|
|
Syntax}). In addition to the prefix, each stream record contains a
|
|
@code{@var{string-output}}. This is either raw text (with an implicit new
|
|
line) or a quoted C string (which does not contain an implicit newline).
|
|
|
|
@table @code
|
|
@item "~" @var{string-output}
|
|
The console output stream contains text that should be displayed in the
|
|
CLI console window. It contains the textual responses to CLI commands.
|
|
|
|
@item "@@" @var{string-output}
|
|
The target output stream contains any textual output from the running
|
|
target. This is only present when GDB's event loop is truly
|
|
asynchronous, which is currently only the case for remote targets.
|
|
|
|
@item "&" @var{string-output}
|
|
The log stream contains debugging messages being produced by @value{GDBN}'s
|
|
internals.
|
|
@end table
|
|
|
|
@node GDB/MI Async Records
|
|
@subsection @sc{gdb/mi} Async Records
|
|
|
|
@cindex async records in @sc{gdb/mi}
|
|
@cindex @sc{gdb/mi}, async records
|
|
@dfn{Async} records are used to notify the @sc{gdb/mi} client of
|
|
additional changes that have occurred. Those changes can either be a
|
|
consequence of @sc{gdb/mi} commands (e.g., a breakpoint modified) or a result of
|
|
target activity (e.g., target stopped).
|
|
|
|
The following is the list of possible async records:
|
|
|
|
@table @code
|
|
|
|
@item *running,thread-id="@var{thread}"
|
|
The target is now running. The @var{thread} field tells which
|
|
specific thread is now running, and can be @samp{all} if all threads
|
|
are running. The frontend should assume that no interaction with a
|
|
running thread is possible after this notification is produced.
|
|
The frontend should not assume that this notification is output
|
|
only once for any command. @value{GDBN} may emit this notification
|
|
several times, either for different threads, because it cannot resume
|
|
all threads together, or even for a single thread, if the thread must
|
|
be stepped though some code before letting it run freely.
|
|
|
|
@item *stopped,reason="@var{reason}",thread-id="@var{id}",stopped-threads="@var{stopped}",core="@var{core}"
|
|
The target has stopped. The @var{reason} field can have one of the
|
|
following values:
|
|
|
|
@table @code
|
|
@item breakpoint-hit
|
|
A breakpoint was reached.
|
|
@item watchpoint-trigger
|
|
A watchpoint was triggered.
|
|
@item read-watchpoint-trigger
|
|
A read watchpoint was triggered.
|
|
@item access-watchpoint-trigger
|
|
An access watchpoint was triggered.
|
|
@item function-finished
|
|
An -exec-finish or similar CLI command was accomplished.
|
|
@item location-reached
|
|
An -exec-until or similar CLI command was accomplished.
|
|
@item watchpoint-scope
|
|
A watchpoint has gone out of scope.
|
|
@item end-stepping-range
|
|
An -exec-next, -exec-next-instruction, -exec-step, -exec-step-instruction or
|
|
similar CLI command was accomplished.
|
|
@item exited-signalled
|
|
The inferior exited because of a signal.
|
|
@item exited
|
|
The inferior exited.
|
|
@item exited-normally
|
|
The inferior exited normally.
|
|
@item signal-received
|
|
A signal was received by the inferior.
|
|
@item solib-event
|
|
The inferior has stopped due to a library being loaded or unloaded.
|
|
This can happen when @code{stop-on-solib-events} (@pxref{Files}) is
|
|
set or when a @code{catch load} or @code{catch unload} catchpoint is
|
|
in use (@pxref{Set Catchpoints}).
|
|
@item fork
|
|
The inferior has forked. This is reported when @code{catch fork}
|
|
(@pxref{Set Catchpoints}) has been used.
|
|
@item vfork
|
|
The inferior has vforked. This is reported in when @code{catch vfork}
|
|
(@pxref{Set Catchpoints}) has been used.
|
|
@item syscall-entry
|
|
The inferior entered a system call. This is reported when @code{catch
|
|
syscall} (@pxref{Set Catchpoints}) has been used.
|
|
@item syscall-entry
|
|
The inferior returned from a system call. This is reported when
|
|
@code{catch syscall} (@pxref{Set Catchpoints}) has been used.
|
|
@item exec
|
|
The inferior called @code{exec}. This is reported when @code{catch exec}
|
|
(@pxref{Set Catchpoints}) has been used.
|
|
@end table
|
|
|
|
The @var{id} field identifies the thread that directly caused the stop
|
|
-- for example by hitting a breakpoint. Depending on whether all-stop
|
|
mode is in effect (@pxref{All-Stop Mode}), @value{GDBN} may either
|
|
stop all threads, or only the thread that directly triggered the stop.
|
|
If all threads are stopped, the @var{stopped} field will have the
|
|
value of @code{"all"}. Otherwise, the value of the @var{stopped}
|
|
field will be a list of thread identifiers. Presently, this list will
|
|
always include a single thread, but frontend should be prepared to see
|
|
several threads in the list. The @var{core} field reports the
|
|
processor core on which the stop event has happened. This field may be absent
|
|
if such information is not available.
|
|
|
|
@item =thread-group-added,id="@var{id}"
|
|
@itemx =thread-group-removed,id="@var{id}"
|
|
A thread group was either added or removed. The @var{id} field
|
|
contains the @value{GDBN} identifier of the thread group. When a thread
|
|
group is added, it generally might not be associated with a running
|
|
process. When a thread group is removed, its id becomes invalid and
|
|
cannot be used in any way.
|
|
|
|
@item =thread-group-started,id="@var{id}",pid="@var{pid}"
|
|
A thread group became associated with a running program,
|
|
either because the program was just started or the thread group
|
|
was attached to a program. The @var{id} field contains the
|
|
@value{GDBN} identifier of the thread group. The @var{pid} field
|
|
contains process identifier, specific to the operating system.
|
|
|
|
@item =thread-group-exited,id="@var{id}"[,exit-code="@var{code}"]
|
|
A thread group is no longer associated with a running program,
|
|
either because the program has exited, or because it was detached
|
|
from. The @var{id} field contains the @value{GDBN} identifier of the
|
|
thread group. @var{code} is the exit code of the inferior; it exists
|
|
only when the inferior exited with some code.
|
|
|
|
@item =thread-created,id="@var{id}",group-id="@var{gid}"
|
|
@itemx =thread-exited,id="@var{id}",group-id="@var{gid}"
|
|
A thread either was created, or has exited. The @var{id} field
|
|
contains the @value{GDBN} identifier of the thread. The @var{gid}
|
|
field identifies the thread group this thread belongs to.
|
|
|
|
@item =thread-selected,id="@var{id}"
|
|
Informs that the selected thread was changed as result of the last
|
|
command. This notification is not emitted as result of @code{-thread-select}
|
|
command but is emitted whenever an MI command that is not documented
|
|
to change the selected thread actually changes it. In particular,
|
|
invoking, directly or indirectly (via user-defined command), the CLI
|
|
@code{thread} command, will generate this notification.
|
|
|
|
We suggest that in response to this notification, front ends
|
|
highlight the selected thread and cause subsequent commands to apply to
|
|
that thread.
|
|
|
|
@item =library-loaded,...
|
|
Reports that a new library file was loaded by the program. This
|
|
notification has 4 fields---@var{id}, @var{target-name},
|
|
@var{host-name}, and @var{symbols-loaded}. The @var{id} field is an
|
|
opaque identifier of the library. For remote debugging case,
|
|
@var{target-name} and @var{host-name} fields give the name of the
|
|
library file on the target, and on the host respectively. For native
|
|
debugging, both those fields have the same value. The
|
|
@var{symbols-loaded} field is emitted only for backward compatibility
|
|
and should not be relied on to convey any useful information. The
|
|
@var{thread-group} field, if present, specifies the id of the thread
|
|
group in whose context the library was loaded. If the field is
|
|
absent, it means the library was loaded in the context of all present
|
|
thread groups.
|
|
|
|
@item =library-unloaded,...
|
|
Reports that a library was unloaded by the program. This notification
|
|
has 3 fields---@var{id}, @var{target-name} and @var{host-name} with
|
|
the same meaning as for the @code{=library-loaded} notification.
|
|
The @var{thread-group} field, if present, specifies the id of the
|
|
thread group in whose context the library was unloaded. If the field is
|
|
absent, it means the library was unloaded in the context of all present
|
|
thread groups.
|
|
|
|
@item =breakpoint-created,bkpt=@{...@}
|
|
@itemx =breakpoint-modified,bkpt=@{...@}
|
|
@itemx =breakpoint-deleted,id=@var{number}
|
|
Reports that a breakpoint was created, modified, or deleted,
|
|
respectively. Only user-visible breakpoints are reported to the MI
|
|
user.
|
|
|
|
The @var{bkpt} argument is of the same form as returned by the various
|
|
breakpoint commands; @xref{GDB/MI Breakpoint Commands}. The
|
|
@var{number} is the ordinal number of the breakpoint.
|
|
|
|
Note that if a breakpoint is emitted in the result record of a
|
|
command, then it will not also be emitted in an async record.
|
|
|
|
@item =cmd-param-changed,param=@var{param},value=@var{value}
|
|
Reports that a parameter of the command @code{set @var{param}} is
|
|
changed to @var{value}. In the multi-word @code{set} command,
|
|
the @var{param} is the whole parameter list to @code{set} command.
|
|
For example, In command @code{set check type on}, @var{param}
|
|
is @code{check type} and @var{value} is @code{on}.
|
|
@end table
|
|
|
|
@node GDB/MI Frame Information
|
|
@subsection @sc{gdb/mi} Frame Information
|
|
|
|
Response from many MI commands includes an information about stack
|
|
frame. This information is a tuple that may have the following
|
|
fields:
|
|
|
|
@table @code
|
|
@item level
|
|
The level of the stack frame. The innermost frame has the level of
|
|
zero. This field is always present.
|
|
|
|
@item func
|
|
The name of the function corresponding to the frame. This field may
|
|
be absent if @value{GDBN} is unable to determine the function name.
|
|
|
|
@item addr
|
|
The code address for the frame. This field is always present.
|
|
|
|
@item file
|
|
The name of the source files that correspond to the frame's code
|
|
address. This field may be absent.
|
|
|
|
@item line
|
|
The source line corresponding to the frames' code address. This field
|
|
may be absent.
|
|
|
|
@item from
|
|
The name of the binary file (either executable or shared library) the
|
|
corresponds to the frame's code address. This field may be absent.
|
|
|
|
@end table
|
|
|
|
@node GDB/MI Thread Information
|
|
@subsection @sc{gdb/mi} Thread Information
|
|
|
|
Whenever @value{GDBN} has to report an information about a thread, it
|
|
uses a tuple with the following fields:
|
|
|
|
@table @code
|
|
@item id
|
|
The numeric id assigned to the thread by @value{GDBN}. This field is
|
|
always present.
|
|
|
|
@item target-id
|
|
Target-specific string identifying the thread. This field is always present.
|
|
|
|
@item details
|
|
Additional information about the thread provided by the target.
|
|
It is supposed to be human-readable and not interpreted by the
|
|
frontend. This field is optional.
|
|
|
|
@item state
|
|
Either @samp{stopped} or @samp{running}, depending on whether the
|
|
thread is presently running. This field is always present.
|
|
|
|
@item core
|
|
The value of this field is an integer number of the processor core the
|
|
thread was last seen on. This field is optional.
|
|
@end table
|
|
|
|
@node GDB/MI Ada Exception Information
|
|
@subsection @sc{gdb/mi} Ada Exception Information
|
|
|
|
Whenever a @code{*stopped} record is emitted because the program
|
|
stopped after hitting an exception catchpoint (@pxref{Set Catchpoints}),
|
|
@value{GDBN} provides the name of the exception that was raised via
|
|
the @code{exception-name} field.
|
|
|
|
@c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
@node GDB/MI Simple Examples
|
|
@section Simple Examples of @sc{gdb/mi} Interaction
|
|
@cindex @sc{gdb/mi}, simple examples
|
|
|
|
This subsection presents several simple examples of interaction using
|
|
the @sc{gdb/mi} interface. In these examples, @samp{->} means that the
|
|
following line is passed to @sc{gdb/mi} as input, while @samp{<-} means
|
|
the output received from @sc{gdb/mi}.
|
|
|
|
Note the line breaks shown in the examples are here only for
|
|
readability, they don't appear in the real output.
|
|
|
|
@subheading Setting a Breakpoint
|
|
|
|
Setting a breakpoint generates synchronous output which contains detailed
|
|
information of the breakpoint.
|
|
|
|
@smallexample
|
|
-> -break-insert main
|
|
<- ^done,bkpt=@{number="1",type="breakpoint",disp="keep",
|
|
enabled="y",addr="0x08048564",func="main",file="myprog.c",
|
|
fullname="/home/nickrob/myprog.c",line="68",times="0"@}
|
|
<- (gdb)
|
|
@end smallexample
|
|
|
|
@subheading Program Execution
|
|
|
|
Program execution generates asynchronous records and MI gives the
|
|
reason that execution stopped.
|
|
|
|
@smallexample
|
|
-> -exec-run
|
|
<- ^running
|
|
<- (gdb)
|
|
<- *stopped,reason="breakpoint-hit",disp="keep",bkptno="1",thread-id="0",
|
|
frame=@{addr="0x08048564",func="main",
|
|
args=[@{name="argc",value="1"@},@{name="argv",value="0xbfc4d4d4"@}],
|
|
file="myprog.c",fullname="/home/nickrob/myprog.c",line="68"@}
|
|
<- (gdb)
|
|
-> -exec-continue
|
|
<- ^running
|
|
<- (gdb)
|
|
<- *stopped,reason="exited-normally"
|
|
<- (gdb)
|
|
@end smallexample
|
|
|
|
@subheading Quitting @value{GDBN}
|
|
|
|
Quitting @value{GDBN} just prints the result class @samp{^exit}.
|
|
|
|
@smallexample
|
|
-> (gdb)
|
|
<- -gdb-exit
|
|
<- ^exit
|
|
@end smallexample
|
|
|
|
Please note that @samp{^exit} is printed immediately, but it might
|
|
take some time for @value{GDBN} to actually exit. During that time, @value{GDBN}
|
|
performs necessary cleanups, including killing programs being debugged
|
|
or disconnecting from debug hardware, so the frontend should wait till
|
|
@value{GDBN} exits and should only forcibly kill @value{GDBN} if it
|
|
fails to exit in reasonable time.
|
|
|
|
@subheading A Bad Command
|
|
|
|
Here's what happens if you pass a non-existent command:
|
|
|
|
@smallexample
|
|
-> -rubbish
|
|
<- ^error,msg="Undefined MI command: rubbish"
|
|
<- (gdb)
|
|
@end smallexample
|
|
|
|
|
|
@c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
@node GDB/MI Command Description Format
|
|
@section @sc{gdb/mi} Command Description Format
|
|
|
|
The remaining sections describe blocks of commands. Each block of
|
|
commands is laid out in a fashion similar to this section.
|
|
|
|
@subheading Motivation
|
|
|
|
The motivation for this collection of commands.
|
|
|
|
@subheading Introduction
|
|
|
|
A brief introduction to this collection of commands as a whole.
|
|
|
|
@subheading Commands
|
|
|
|
For each command in the block, the following is described:
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-command @var{args}@dots{}
|
|
@end smallexample
|
|
|
|
@subsubheading Result
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} CLI command(s), if any.
|
|
|
|
@subsubheading Example
|
|
|
|
Example(s) formatted for readability. Some of the described commands have
|
|
not been implemented yet and these are labeled N.A.@: (not available).
|
|
|
|
|
|
@c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
@node GDB/MI Breakpoint Commands
|
|
@section @sc{gdb/mi} Breakpoint Commands
|
|
|
|
@cindex breakpoint commands for @sc{gdb/mi}
|
|
@cindex @sc{gdb/mi}, breakpoint commands
|
|
This section documents @sc{gdb/mi} commands for manipulating
|
|
breakpoints.
|
|
|
|
@subheading The @code{-break-after} Command
|
|
@findex -break-after
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-break-after @var{number} @var{count}
|
|
@end smallexample
|
|
|
|
The breakpoint number @var{number} is not in effect until it has been
|
|
hit @var{count} times. To see how this is reflected in the output of
|
|
the @samp{-break-list} command, see the description of the
|
|
@samp{-break-list} command below.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} command is @samp{ignore}.
|
|
|
|
@subsubheading Example
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-break-insert main
|
|
^done,bkpt=@{number="1",type="breakpoint",disp="keep",
|
|
enabled="y",addr="0x000100d0",func="main",file="hello.c",
|
|
fullname="/home/foo/hello.c",line="5",times="0"@}
|
|
(gdb)
|
|
-break-after 1 3
|
|
~
|
|
^done
|
|
(gdb)
|
|
-break-list
|
|
^done,BreakpointTable=@{nr_rows="1",nr_cols="6",
|
|
hdr=[@{width="3",alignment="-1",col_name="number",colhdr="Num"@},
|
|
@{width="14",alignment="-1",col_name="type",colhdr="Type"@},
|
|
@{width="4",alignment="-1",col_name="disp",colhdr="Disp"@},
|
|
@{width="3",alignment="-1",col_name="enabled",colhdr="Enb"@},
|
|
@{width="10",alignment="-1",col_name="addr",colhdr="Address"@},
|
|
@{width="40",alignment="2",col_name="what",colhdr="What"@}],
|
|
body=[bkpt=@{number="1",type="breakpoint",disp="keep",enabled="y",
|
|
addr="0x000100d0",func="main",file="hello.c",fullname="/home/foo/hello.c",
|
|
line="5",times="0",ignore="3"@}]@}
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
@ignore
|
|
@subheading The @code{-break-catch} Command
|
|
@findex -break-catch
|
|
@end ignore
|
|
|
|
@subheading The @code{-break-commands} Command
|
|
@findex -break-commands
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-break-commands @var{number} [ @var{command1} ... @var{commandN} ]
|
|
@end smallexample
|
|
|
|
Specifies the CLI commands that should be executed when breakpoint
|
|
@var{number} is hit. The parameters @var{command1} to @var{commandN}
|
|
are the commands. If no command is specified, any previously-set
|
|
commands are cleared. @xref{Break Commands}. Typical use of this
|
|
functionality is tracing a program, that is, printing of values of
|
|
some variables whenever breakpoint is hit and then continuing.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} command is @samp{commands}.
|
|
|
|
@subsubheading Example
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-break-insert main
|
|
^done,bkpt=@{number="1",type="breakpoint",disp="keep",
|
|
enabled="y",addr="0x000100d0",func="main",file="hello.c",
|
|
fullname="/home/foo/hello.c",line="5",times="0"@}
|
|
(gdb)
|
|
-break-commands 1 "print v" "continue"
|
|
^done
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
@subheading The @code{-break-condition} Command
|
|
@findex -break-condition
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-break-condition @var{number} @var{expr}
|
|
@end smallexample
|
|
|
|
Breakpoint @var{number} will stop the program only if the condition in
|
|
@var{expr} is true. The condition becomes part of the
|
|
@samp{-break-list} output (see the description of the @samp{-break-list}
|
|
command below).
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} command is @samp{condition}.
|
|
|
|
@subsubheading Example
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-break-condition 1 1
|
|
^done
|
|
(gdb)
|
|
-break-list
|
|
^done,BreakpointTable=@{nr_rows="1",nr_cols="6",
|
|
hdr=[@{width="3",alignment="-1",col_name="number",colhdr="Num"@},
|
|
@{width="14",alignment="-1",col_name="type",colhdr="Type"@},
|
|
@{width="4",alignment="-1",col_name="disp",colhdr="Disp"@},
|
|
@{width="3",alignment="-1",col_name="enabled",colhdr="Enb"@},
|
|
@{width="10",alignment="-1",col_name="addr",colhdr="Address"@},
|
|
@{width="40",alignment="2",col_name="what",colhdr="What"@}],
|
|
body=[bkpt=@{number="1",type="breakpoint",disp="keep",enabled="y",
|
|
addr="0x000100d0",func="main",file="hello.c",fullname="/home/foo/hello.c",
|
|
line="5",cond="1",times="0",ignore="3"@}]@}
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
@subheading The @code{-break-delete} Command
|
|
@findex -break-delete
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-break-delete ( @var{breakpoint} )+
|
|
@end smallexample
|
|
|
|
Delete the breakpoint(s) whose number(s) are specified in the argument
|
|
list. This is obviously reflected in the breakpoint list.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} command is @samp{delete}.
|
|
|
|
@subsubheading Example
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-break-delete 1
|
|
^done
|
|
(gdb)
|
|
-break-list
|
|
^done,BreakpointTable=@{nr_rows="0",nr_cols="6",
|
|
hdr=[@{width="3",alignment="-1",col_name="number",colhdr="Num"@},
|
|
@{width="14",alignment="-1",col_name="type",colhdr="Type"@},
|
|
@{width="4",alignment="-1",col_name="disp",colhdr="Disp"@},
|
|
@{width="3",alignment="-1",col_name="enabled",colhdr="Enb"@},
|
|
@{width="10",alignment="-1",col_name="addr",colhdr="Address"@},
|
|
@{width="40",alignment="2",col_name="what",colhdr="What"@}],
|
|
body=[]@}
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
@subheading The @code{-break-disable} Command
|
|
@findex -break-disable
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-break-disable ( @var{breakpoint} )+
|
|
@end smallexample
|
|
|
|
Disable the named @var{breakpoint}(s). The field @samp{enabled} in the
|
|
break list is now set to @samp{n} for the named @var{breakpoint}(s).
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} command is @samp{disable}.
|
|
|
|
@subsubheading Example
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-break-disable 2
|
|
^done
|
|
(gdb)
|
|
-break-list
|
|
^done,BreakpointTable=@{nr_rows="1",nr_cols="6",
|
|
hdr=[@{width="3",alignment="-1",col_name="number",colhdr="Num"@},
|
|
@{width="14",alignment="-1",col_name="type",colhdr="Type"@},
|
|
@{width="4",alignment="-1",col_name="disp",colhdr="Disp"@},
|
|
@{width="3",alignment="-1",col_name="enabled",colhdr="Enb"@},
|
|
@{width="10",alignment="-1",col_name="addr",colhdr="Address"@},
|
|
@{width="40",alignment="2",col_name="what",colhdr="What"@}],
|
|
body=[bkpt=@{number="2",type="breakpoint",disp="keep",enabled="n",
|
|
addr="0x000100d0",func="main",file="hello.c",fullname="/home/foo/hello.c",
|
|
line="5",times="0"@}]@}
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
@subheading The @code{-break-enable} Command
|
|
@findex -break-enable
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-break-enable ( @var{breakpoint} )+
|
|
@end smallexample
|
|
|
|
Enable (previously disabled) @var{breakpoint}(s).
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} command is @samp{enable}.
|
|
|
|
@subsubheading Example
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-break-enable 2
|
|
^done
|
|
(gdb)
|
|
-break-list
|
|
^done,BreakpointTable=@{nr_rows="1",nr_cols="6",
|
|
hdr=[@{width="3",alignment="-1",col_name="number",colhdr="Num"@},
|
|
@{width="14",alignment="-1",col_name="type",colhdr="Type"@},
|
|
@{width="4",alignment="-1",col_name="disp",colhdr="Disp"@},
|
|
@{width="3",alignment="-1",col_name="enabled",colhdr="Enb"@},
|
|
@{width="10",alignment="-1",col_name="addr",colhdr="Address"@},
|
|
@{width="40",alignment="2",col_name="what",colhdr="What"@}],
|
|
body=[bkpt=@{number="2",type="breakpoint",disp="keep",enabled="y",
|
|
addr="0x000100d0",func="main",file="hello.c",fullname="/home/foo/hello.c",
|
|
line="5",times="0"@}]@}
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
@subheading The @code{-break-info} Command
|
|
@findex -break-info
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-break-info @var{breakpoint}
|
|
@end smallexample
|
|
|
|
@c REDUNDANT???
|
|
Get information about a single breakpoint.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} command is @samp{info break @var{breakpoint}}.
|
|
|
|
@subsubheading Example
|
|
N.A.
|
|
|
|
@subheading The @code{-break-insert} Command
|
|
@findex -break-insert
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-break-insert [ -t ] [ -h ] [ -f ] [ -d ] [ -a ]
|
|
[ -c @var{condition} ] [ -i @var{ignore-count} ]
|
|
[ -p @var{thread-id} ] [ @var{location} ]
|
|
@end smallexample
|
|
|
|
@noindent
|
|
If specified, @var{location}, can be one of:
|
|
|
|
@itemize @bullet
|
|
@item function
|
|
@c @item +offset
|
|
@c @item -offset
|
|
@c @item linenum
|
|
@item filename:linenum
|
|
@item filename:function
|
|
@item *address
|
|
@end itemize
|
|
|
|
The possible optional parameters of this command are:
|
|
|
|
@table @samp
|
|
@item -t
|
|
Insert a temporary breakpoint.
|
|
@item -h
|
|
Insert a hardware breakpoint.
|
|
@item -f
|
|
If @var{location} cannot be parsed (for example if it
|
|
refers to unknown files or functions), create a pending
|
|
breakpoint. Without this flag, @value{GDBN} will report
|
|
an error, and won't create a breakpoint, if @var{location}
|
|
cannot be parsed.
|
|
@item -d
|
|
Create a disabled breakpoint.
|
|
@item -a
|
|
Create a tracepoint. @xref{Tracepoints}. When this parameter
|
|
is used together with @samp{-h}, a fast tracepoint is created.
|
|
@item -c @var{condition}
|
|
Make the breakpoint conditional on @var{condition}.
|
|
@item -i @var{ignore-count}
|
|
Initialize the @var{ignore-count}.
|
|
@item -p @var{thread-id}
|
|
Restrict the breakpoint to the specified @var{thread-id}.
|
|
@end table
|
|
|
|
@subsubheading Result
|
|
|
|
The result is in the form:
|
|
|
|
@smallexample
|
|
^done,bkpt=@{number="@var{number}",type="@var{type}",disp="del"|"keep",
|
|
enabled="y"|"n",addr="@var{hex}",func="@var{funcname}",file="@var{filename}",
|
|
fullname="@var{full_filename}",line="@var{lineno}",[thread="@var{threadno},]
|
|
times="@var{times}"@}
|
|
@end smallexample
|
|
|
|
@noindent
|
|
where @var{number} is the @value{GDBN} number for this breakpoint,
|
|
@var{funcname} is the name of the function where the breakpoint was
|
|
inserted, @var{filename} is the name of the source file which contains
|
|
this function, @var{lineno} is the source line number within that file
|
|
and @var{times} the number of times that the breakpoint has been hit
|
|
(always 0 for -break-insert but may be greater for -break-info or -break-list
|
|
which use the same output).
|
|
|
|
Note: this format is open to change.
|
|
@c An out-of-band breakpoint instead of part of the result?
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} commands are @samp{break}, @samp{tbreak},
|
|
@samp{hbreak}, and @samp{thbreak}. @c and @samp{rbreak}.
|
|
|
|
@subsubheading Example
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-break-insert main
|
|
^done,bkpt=@{number="1",addr="0x0001072c",file="recursive2.c",
|
|
fullname="/home/foo/recursive2.c,line="4",times="0"@}
|
|
(gdb)
|
|
-break-insert -t foo
|
|
^done,bkpt=@{number="2",addr="0x00010774",file="recursive2.c",
|
|
fullname="/home/foo/recursive2.c,line="11",times="0"@}
|
|
(gdb)
|
|
-break-list
|
|
^done,BreakpointTable=@{nr_rows="2",nr_cols="6",
|
|
hdr=[@{width="3",alignment="-1",col_name="number",colhdr="Num"@},
|
|
@{width="14",alignment="-1",col_name="type",colhdr="Type"@},
|
|
@{width="4",alignment="-1",col_name="disp",colhdr="Disp"@},
|
|
@{width="3",alignment="-1",col_name="enabled",colhdr="Enb"@},
|
|
@{width="10",alignment="-1",col_name="addr",colhdr="Address"@},
|
|
@{width="40",alignment="2",col_name="what",colhdr="What"@}],
|
|
body=[bkpt=@{number="1",type="breakpoint",disp="keep",enabled="y",
|
|
addr="0x0001072c", func="main",file="recursive2.c",
|
|
fullname="/home/foo/recursive2.c,"line="4",times="0"@},
|
|
bkpt=@{number="2",type="breakpoint",disp="del",enabled="y",
|
|
addr="0x00010774",func="foo",file="recursive2.c",
|
|
fullname="/home/foo/recursive2.c",line="11",times="0"@}]@}
|
|
(gdb)
|
|
@c -break-insert -r foo.*
|
|
@c ~int foo(int, int);
|
|
@c ^done,bkpt=@{number="3",addr="0x00010774",file="recursive2.c,
|
|
@c "fullname="/home/foo/recursive2.c",line="11",times="0"@}
|
|
@c (gdb)
|
|
@end smallexample
|
|
|
|
@subheading The @code{-break-list} Command
|
|
@findex -break-list
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-break-list
|
|
@end smallexample
|
|
|
|
Displays the list of inserted breakpoints, showing the following fields:
|
|
|
|
@table @samp
|
|
@item Number
|
|
number of the breakpoint
|
|
@item Type
|
|
type of the breakpoint: @samp{breakpoint} or @samp{watchpoint}
|
|
@item Disposition
|
|
should the breakpoint be deleted or disabled when it is hit: @samp{keep}
|
|
or @samp{nokeep}
|
|
@item Enabled
|
|
is the breakpoint enabled or no: @samp{y} or @samp{n}
|
|
@item Address
|
|
memory location at which the breakpoint is set
|
|
@item What
|
|
logical location of the breakpoint, expressed by function name, file
|
|
name, line number
|
|
@item Times
|
|
number of times the breakpoint has been hit
|
|
@end table
|
|
|
|
If there are no breakpoints or watchpoints, the @code{BreakpointTable}
|
|
@code{body} field is an empty list.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} command is @samp{info break}.
|
|
|
|
@subsubheading Example
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-break-list
|
|
^done,BreakpointTable=@{nr_rows="2",nr_cols="6",
|
|
hdr=[@{width="3",alignment="-1",col_name="number",colhdr="Num"@},
|
|
@{width="14",alignment="-1",col_name="type",colhdr="Type"@},
|
|
@{width="4",alignment="-1",col_name="disp",colhdr="Disp"@},
|
|
@{width="3",alignment="-1",col_name="enabled",colhdr="Enb"@},
|
|
@{width="10",alignment="-1",col_name="addr",colhdr="Address"@},
|
|
@{width="40",alignment="2",col_name="what",colhdr="What"@}],
|
|
body=[bkpt=@{number="1",type="breakpoint",disp="keep",enabled="y",
|
|
addr="0x000100d0",func="main",file="hello.c",line="5",times="0"@},
|
|
bkpt=@{number="2",type="breakpoint",disp="keep",enabled="y",
|
|
addr="0x00010114",func="foo",file="hello.c",fullname="/home/foo/hello.c",
|
|
line="13",times="0"@}]@}
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
Here's an example of the result when there are no breakpoints:
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-break-list
|
|
^done,BreakpointTable=@{nr_rows="0",nr_cols="6",
|
|
hdr=[@{width="3",alignment="-1",col_name="number",colhdr="Num"@},
|
|
@{width="14",alignment="-1",col_name="type",colhdr="Type"@},
|
|
@{width="4",alignment="-1",col_name="disp",colhdr="Disp"@},
|
|
@{width="3",alignment="-1",col_name="enabled",colhdr="Enb"@},
|
|
@{width="10",alignment="-1",col_name="addr",colhdr="Address"@},
|
|
@{width="40",alignment="2",col_name="what",colhdr="What"@}],
|
|
body=[]@}
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
@subheading The @code{-break-passcount} Command
|
|
@findex -break-passcount
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-break-passcount @var{tracepoint-number} @var{passcount}
|
|
@end smallexample
|
|
|
|
Set the passcount for tracepoint @var{tracepoint-number} to
|
|
@var{passcount}. If the breakpoint referred to by @var{tracepoint-number}
|
|
is not a tracepoint, error is emitted. This corresponds to CLI
|
|
command @samp{passcount}.
|
|
|
|
@subheading The @code{-break-watch} Command
|
|
@findex -break-watch
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-break-watch [ -a | -r ]
|
|
@end smallexample
|
|
|
|
Create a watchpoint. With the @samp{-a} option it will create an
|
|
@dfn{access} watchpoint, i.e., a watchpoint that triggers either on a
|
|
read from or on a write to the memory location. With the @samp{-r}
|
|
option, the watchpoint created is a @dfn{read} watchpoint, i.e., it will
|
|
trigger only when the memory location is accessed for reading. Without
|
|
either of the options, the watchpoint created is a regular watchpoint,
|
|
i.e., it will trigger when the memory location is accessed for writing.
|
|
@xref{Set Watchpoints, , Setting Watchpoints}.
|
|
|
|
Note that @samp{-break-list} will report a single list of watchpoints and
|
|
breakpoints inserted.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} commands are @samp{watch}, @samp{awatch}, and
|
|
@samp{rwatch}.
|
|
|
|
@subsubheading Example
|
|
|
|
Setting a watchpoint on a variable in the @code{main} function:
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-break-watch x
|
|
^done,wpt=@{number="2",exp="x"@}
|
|
(gdb)
|
|
-exec-continue
|
|
^running
|
|
(gdb)
|
|
*stopped,reason="watchpoint-trigger",wpt=@{number="2",exp="x"@},
|
|
value=@{old="-268439212",new="55"@},
|
|
frame=@{func="main",args=[],file="recursive2.c",
|
|
fullname="/home/foo/bar/recursive2.c",line="5"@}
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
Setting a watchpoint on a variable local to a function. @value{GDBN} will stop
|
|
the program execution twice: first for the variable changing value, then
|
|
for the watchpoint going out of scope.
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-break-watch C
|
|
^done,wpt=@{number="5",exp="C"@}
|
|
(gdb)
|
|
-exec-continue
|
|
^running
|
|
(gdb)
|
|
*stopped,reason="watchpoint-trigger",
|
|
wpt=@{number="5",exp="C"@},value=@{old="-276895068",new="3"@},
|
|
frame=@{func="callee4",args=[],
|
|
file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
|
|
fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="13"@}
|
|
(gdb)
|
|
-exec-continue
|
|
^running
|
|
(gdb)
|
|
*stopped,reason="watchpoint-scope",wpnum="5",
|
|
frame=@{func="callee3",args=[@{name="strarg",
|
|
value="0x11940 \"A string argument.\""@}],
|
|
file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
|
|
fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="18"@}
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
Listing breakpoints and watchpoints, at different points in the program
|
|
execution. Note that once the watchpoint goes out of scope, it is
|
|
deleted.
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-break-watch C
|
|
^done,wpt=@{number="2",exp="C"@}
|
|
(gdb)
|
|
-break-list
|
|
^done,BreakpointTable=@{nr_rows="2",nr_cols="6",
|
|
hdr=[@{width="3",alignment="-1",col_name="number",colhdr="Num"@},
|
|
@{width="14",alignment="-1",col_name="type",colhdr="Type"@},
|
|
@{width="4",alignment="-1",col_name="disp",colhdr="Disp"@},
|
|
@{width="3",alignment="-1",col_name="enabled",colhdr="Enb"@},
|
|
@{width="10",alignment="-1",col_name="addr",colhdr="Address"@},
|
|
@{width="40",alignment="2",col_name="what",colhdr="What"@}],
|
|
body=[bkpt=@{number="1",type="breakpoint",disp="keep",enabled="y",
|
|
addr="0x00010734",func="callee4",
|
|
file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
|
|
fullname="/home/foo/devo/gdb/testsuite/gdb.mi/basics.c"line="8",times="1"@},
|
|
bkpt=@{number="2",type="watchpoint",disp="keep",
|
|
enabled="y",addr="",what="C",times="0"@}]@}
|
|
(gdb)
|
|
-exec-continue
|
|
^running
|
|
(gdb)
|
|
*stopped,reason="watchpoint-trigger",wpt=@{number="2",exp="C"@},
|
|
value=@{old="-276895068",new="3"@},
|
|
frame=@{func="callee4",args=[],
|
|
file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
|
|
fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="13"@}
|
|
(gdb)
|
|
-break-list
|
|
^done,BreakpointTable=@{nr_rows="2",nr_cols="6",
|
|
hdr=[@{width="3",alignment="-1",col_name="number",colhdr="Num"@},
|
|
@{width="14",alignment="-1",col_name="type",colhdr="Type"@},
|
|
@{width="4",alignment="-1",col_name="disp",colhdr="Disp"@},
|
|
@{width="3",alignment="-1",col_name="enabled",colhdr="Enb"@},
|
|
@{width="10",alignment="-1",col_name="addr",colhdr="Address"@},
|
|
@{width="40",alignment="2",col_name="what",colhdr="What"@}],
|
|
body=[bkpt=@{number="1",type="breakpoint",disp="keep",enabled="y",
|
|
addr="0x00010734",func="callee4",
|
|
file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
|
|
fullname="/home/foo/devo/gdb/testsuite/gdb.mi/basics.c",line="8",times="1"@},
|
|
bkpt=@{number="2",type="watchpoint",disp="keep",
|
|
enabled="y",addr="",what="C",times="-5"@}]@}
|
|
(gdb)
|
|
-exec-continue
|
|
^running
|
|
^done,reason="watchpoint-scope",wpnum="2",
|
|
frame=@{func="callee3",args=[@{name="strarg",
|
|
value="0x11940 \"A string argument.\""@}],
|
|
file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
|
|
fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="18"@}
|
|
(gdb)
|
|
-break-list
|
|
^done,BreakpointTable=@{nr_rows="1",nr_cols="6",
|
|
hdr=[@{width="3",alignment="-1",col_name="number",colhdr="Num"@},
|
|
@{width="14",alignment="-1",col_name="type",colhdr="Type"@},
|
|
@{width="4",alignment="-1",col_name="disp",colhdr="Disp"@},
|
|
@{width="3",alignment="-1",col_name="enabled",colhdr="Enb"@},
|
|
@{width="10",alignment="-1",col_name="addr",colhdr="Address"@},
|
|
@{width="40",alignment="2",col_name="what",colhdr="What"@}],
|
|
body=[bkpt=@{number="1",type="breakpoint",disp="keep",enabled="y",
|
|
addr="0x00010734",func="callee4",
|
|
file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
|
|
fullname="/home/foo/devo/gdb/testsuite/gdb.mi/basics.c",line="8",
|
|
times="1"@}]@}
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
@c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
@node GDB/MI Program Context
|
|
@section @sc{gdb/mi} Program Context
|
|
|
|
@subheading The @code{-exec-arguments} Command
|
|
@findex -exec-arguments
|
|
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-exec-arguments @var{args}
|
|
@end smallexample
|
|
|
|
Set the inferior program arguments, to be used in the next
|
|
@samp{-exec-run}.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} command is @samp{set args}.
|
|
|
|
@subsubheading Example
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-exec-arguments -v word
|
|
^done
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
|
|
@ignore
|
|
@subheading The @code{-exec-show-arguments} Command
|
|
@findex -exec-show-arguments
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-exec-show-arguments
|
|
@end smallexample
|
|
|
|
Print the arguments of the program.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} command is @samp{show args}.
|
|
|
|
@subsubheading Example
|
|
N.A.
|
|
@end ignore
|
|
|
|
|
|
@subheading The @code{-environment-cd} Command
|
|
@findex -environment-cd
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-environment-cd @var{pathdir}
|
|
@end smallexample
|
|
|
|
Set @value{GDBN}'s working directory.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} command is @samp{cd}.
|
|
|
|
@subsubheading Example
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-environment-cd /kwikemart/marge/ezannoni/flathead-dev/devo/gdb
|
|
^done
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
|
|
@subheading The @code{-environment-directory} Command
|
|
@findex -environment-directory
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-environment-directory [ -r ] [ @var{pathdir} ]+
|
|
@end smallexample
|
|
|
|
Add directories @var{pathdir} to beginning of search path for source files.
|
|
If the @samp{-r} option is used, the search path is reset to the default
|
|
search path. If directories @var{pathdir} are supplied in addition to the
|
|
@samp{-r} option, the search path is first reset and then addition
|
|
occurs as normal.
|
|
Multiple directories may be specified, separated by blanks. Specifying
|
|
multiple directories in a single command
|
|
results in the directories added to the beginning of the
|
|
search path in the same order they were presented in the command.
|
|
If blanks are needed as
|
|
part of a directory name, double-quotes should be used around
|
|
the name. In the command output, the path will show up separated
|
|
by the system directory-separator character. The directory-separator
|
|
character must not be used
|
|
in any directory name.
|
|
If no directories are specified, the current search path is displayed.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} command is @samp{dir}.
|
|
|
|
@subsubheading Example
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-environment-directory /kwikemart/marge/ezannoni/flathead-dev/devo/gdb
|
|
^done,source-path="/kwikemart/marge/ezannoni/flathead-dev/devo/gdb:$cdir:$cwd"
|
|
(gdb)
|
|
-environment-directory ""
|
|
^done,source-path="/kwikemart/marge/ezannoni/flathead-dev/devo/gdb:$cdir:$cwd"
|
|
(gdb)
|
|
-environment-directory -r /home/jjohnstn/src/gdb /usr/src
|
|
^done,source-path="/home/jjohnstn/src/gdb:/usr/src:$cdir:$cwd"
|
|
(gdb)
|
|
-environment-directory -r
|
|
^done,source-path="$cdir:$cwd"
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
|
|
@subheading The @code{-environment-path} Command
|
|
@findex -environment-path
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-environment-path [ -r ] [ @var{pathdir} ]+
|
|
@end smallexample
|
|
|
|
Add directories @var{pathdir} to beginning of search path for object files.
|
|
If the @samp{-r} option is used, the search path is reset to the original
|
|
search path that existed at gdb start-up. If directories @var{pathdir} are
|
|
supplied in addition to the
|
|
@samp{-r} option, the search path is first reset and then addition
|
|
occurs as normal.
|
|
Multiple directories may be specified, separated by blanks. Specifying
|
|
multiple directories in a single command
|
|
results in the directories added to the beginning of the
|
|
search path in the same order they were presented in the command.
|
|
If blanks are needed as
|
|
part of a directory name, double-quotes should be used around
|
|
the name. In the command output, the path will show up separated
|
|
by the system directory-separator character. The directory-separator
|
|
character must not be used
|
|
in any directory name.
|
|
If no directories are specified, the current path is displayed.
|
|
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} command is @samp{path}.
|
|
|
|
@subsubheading Example
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-environment-path
|
|
^done,path="/usr/bin"
|
|
(gdb)
|
|
-environment-path /kwikemart/marge/ezannoni/flathead-dev/ppc-eabi/gdb /bin
|
|
^done,path="/kwikemart/marge/ezannoni/flathead-dev/ppc-eabi/gdb:/bin:/usr/bin"
|
|
(gdb)
|
|
-environment-path -r /usr/local/bin
|
|
^done,path="/usr/local/bin:/usr/bin"
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
|
|
@subheading The @code{-environment-pwd} Command
|
|
@findex -environment-pwd
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-environment-pwd
|
|
@end smallexample
|
|
|
|
Show the current working directory.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} command is @samp{pwd}.
|
|
|
|
@subsubheading Example
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-environment-pwd
|
|
^done,cwd="/kwikemart/marge/ezannoni/flathead-dev/devo/gdb"
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
@c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
@node GDB/MI Thread Commands
|
|
@section @sc{gdb/mi} Thread Commands
|
|
|
|
|
|
@subheading The @code{-thread-info} Command
|
|
@findex -thread-info
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-thread-info [ @var{thread-id} ]
|
|
@end smallexample
|
|
|
|
Reports information about either a specific thread, if
|
|
the @var{thread-id} parameter is present, or about all
|
|
threads. When printing information about all threads,
|
|
also reports the current thread.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The @samp{info thread} command prints the same information
|
|
about all threads.
|
|
|
|
@subsubheading Result
|
|
|
|
The result is a list of threads. The following attributes are
|
|
defined for a given thread:
|
|
|
|
@table @samp
|
|
@item current
|
|
This field exists only for the current thread. It has the value @samp{*}.
|
|
|
|
@item id
|
|
The identifier that @value{GDBN} uses to refer to the thread.
|
|
|
|
@item target-id
|
|
The identifier that the target uses to refer to the thread.
|
|
|
|
@item details
|
|
Extra information about the thread, in a target-specific format. This
|
|
field is optional.
|
|
|
|
@item name
|
|
The name of the thread. If the user specified a name using the
|
|
@code{thread name} command, then this name is given. Otherwise, if
|
|
@value{GDBN} can extract the thread name from the target, then that
|
|
name is given. If @value{GDBN} cannot find the thread name, then this
|
|
field is omitted.
|
|
|
|
@item frame
|
|
The stack frame currently executing in the thread.
|
|
|
|
@item state
|
|
The thread's state. The @samp{state} field may have the following
|
|
values:
|
|
|
|
@table @code
|
|
@item stopped
|
|
The thread is stopped. Frame information is available for stopped
|
|
threads.
|
|
|
|
@item running
|
|
The thread is running. There's no frame information for running
|
|
threads.
|
|
|
|
@end table
|
|
|
|
@item core
|
|
If @value{GDBN} can find the CPU core on which this thread is running,
|
|
then this field is the core identifier. This field is optional.
|
|
|
|
@end table
|
|
|
|
@subsubheading Example
|
|
|
|
@smallexample
|
|
-thread-info
|
|
^done,threads=[
|
|
@{id="2",target-id="Thread 0xb7e14b90 (LWP 21257)",
|
|
frame=@{level="0",addr="0xffffe410",func="__kernel_vsyscall",
|
|
args=[]@},state="running"@},
|
|
@{id="1",target-id="Thread 0xb7e156b0 (LWP 21254)",
|
|
frame=@{level="0",addr="0x0804891f",func="foo",
|
|
args=[@{name="i",value="10"@}],
|
|
file="/tmp/a.c",fullname="/tmp/a.c",line="158"@},
|
|
state="running"@}],
|
|
current-thread-id="1"
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
@subheading The @code{-thread-list-ids} Command
|
|
@findex -thread-list-ids
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-thread-list-ids
|
|
@end smallexample
|
|
|
|
Produces a list of the currently known @value{GDBN} thread ids. At the
|
|
end of the list it also prints the total number of such threads.
|
|
|
|
This command is retained for historical reasons, the
|
|
@code{-thread-info} command should be used instead.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
Part of @samp{info threads} supplies the same information.
|
|
|
|
@subsubheading Example
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-thread-list-ids
|
|
^done,thread-ids=@{thread-id="3",thread-id="2",thread-id="1"@},
|
|
current-thread-id="1",number-of-threads="3"
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
|
|
@subheading The @code{-thread-select} Command
|
|
@findex -thread-select
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-thread-select @var{threadnum}
|
|
@end smallexample
|
|
|
|
Make @var{threadnum} the current thread. It prints the number of the new
|
|
current thread, and the topmost frame for that thread.
|
|
|
|
This command is deprecated in favor of explicitly using the
|
|
@samp{--thread} option to each command.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} command is @samp{thread}.
|
|
|
|
@subsubheading Example
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-exec-next
|
|
^running
|
|
(gdb)
|
|
*stopped,reason="end-stepping-range",thread-id="2",line="187",
|
|
file="../../../devo/gdb/testsuite/gdb.threads/linux-dp.c"
|
|
(gdb)
|
|
-thread-list-ids
|
|
^done,
|
|
thread-ids=@{thread-id="3",thread-id="2",thread-id="1"@},
|
|
number-of-threads="3"
|
|
(gdb)
|
|
-thread-select 3
|
|
^done,new-thread-id="3",
|
|
frame=@{level="0",func="vprintf",
|
|
args=[@{name="format",value="0x8048e9c \"%*s%c %d %c\\n\""@},
|
|
@{name="arg",value="0x2"@}],file="vprintf.c",line="31"@}
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
@c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
@node GDB/MI Ada Tasking Commands
|
|
@section @sc{gdb/mi} Ada Tasking Commands
|
|
|
|
@subheading The @code{-ada-task-info} Command
|
|
@findex -ada-task-info
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-ada-task-info [ @var{task-id} ]
|
|
@end smallexample
|
|
|
|
Reports information about either a specific Ada task, if the
|
|
@var{task-id} parameter is present, or about all Ada tasks.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The @samp{info tasks} command prints the same information
|
|
about all Ada tasks (@pxref{Ada Tasks}).
|
|
|
|
@subsubheading Result
|
|
|
|
The result is a table of Ada tasks. The following columns are
|
|
defined for each Ada task:
|
|
|
|
@table @samp
|
|
@item current
|
|
This field exists only for the current thread. It has the value @samp{*}.
|
|
|
|
@item id
|
|
The identifier that @value{GDBN} uses to refer to the Ada task.
|
|
|
|
@item task-id
|
|
The identifier that the target uses to refer to the Ada task.
|
|
|
|
@item thread-id
|
|
The identifier of the thread corresponding to the Ada task.
|
|
|
|
This field should always exist, as Ada tasks are always implemented
|
|
on top of a thread. But if @value{GDBN} cannot find this corresponding
|
|
thread for any reason, the field is omitted.
|
|
|
|
@item parent-id
|
|
This field exists only when the task was created by another task.
|
|
In this case, it provides the ID of the parent task.
|
|
|
|
@item priority
|
|
The base priority of the task.
|
|
|
|
@item state
|
|
The current state of the task. For a detailed description of the
|
|
possible states, see @ref{Ada Tasks}.
|
|
|
|
@item name
|
|
The name of the task.
|
|
|
|
@end table
|
|
|
|
@subsubheading Example
|
|
|
|
@smallexample
|
|
-ada-task-info
|
|
^done,tasks=@{nr_rows="3",nr_cols="8",
|
|
hdr=[@{width="1",alignment="-1",col_name="current",colhdr=""@},
|
|
@{width="3",alignment="1",col_name="id",colhdr="ID"@},
|
|
@{width="9",alignment="1",col_name="task-id",colhdr="TID"@},
|
|
@{width="4",alignment="1",col_name="thread-id",colhdr=""@},
|
|
@{width="4",alignment="1",col_name="parent-id",colhdr="P-ID"@},
|
|
@{width="3",alignment="1",col_name="priority",colhdr="Pri"@},
|
|
@{width="22",alignment="-1",col_name="state",colhdr="State"@},
|
|
@{width="1",alignment="2",col_name="name",colhdr="Name"@}],
|
|
body=[@{current="*",id="1",task-id=" 644010",thread-id="1",priority="48",
|
|
state="Child Termination Wait",name="main_task"@}]@}
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
@c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
@node GDB/MI Program Execution
|
|
@section @sc{gdb/mi} Program Execution
|
|
|
|
These are the asynchronous commands which generate the out-of-band
|
|
record @samp{*stopped}. Currently @value{GDBN} only really executes
|
|
asynchronously with remote targets and this interaction is mimicked in
|
|
other cases.
|
|
|
|
@subheading The @code{-exec-continue} Command
|
|
@findex -exec-continue
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-exec-continue [--reverse] [--all|--thread-group N]
|
|
@end smallexample
|
|
|
|
Resumes the execution of the inferior program, which will continue
|
|
to execute until it reaches a debugger stop event. If the
|
|
@samp{--reverse} option is specified, execution resumes in reverse until
|
|
it reaches a stop event. Stop events may include
|
|
@itemize @bullet
|
|
@item
|
|
breakpoints or watchpoints
|
|
@item
|
|
signals or exceptions
|
|
@item
|
|
the end of the process (or its beginning under @samp{--reverse})
|
|
@item
|
|
the end or beginning of a replay log if one is being used.
|
|
@end itemize
|
|
In all-stop mode (@pxref{All-Stop
|
|
Mode}), may resume only one thread, or all threads, depending on the
|
|
value of the @samp{scheduler-locking} variable. If @samp{--all} is
|
|
specified, all threads (in all inferiors) will be resumed. The @samp{--all} option is
|
|
ignored in all-stop mode. If the @samp{--thread-group} options is
|
|
specified, then all threads in that thread group are resumed.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} corresponding is @samp{continue}.
|
|
|
|
@subsubheading Example
|
|
|
|
@smallexample
|
|
-exec-continue
|
|
^running
|
|
(gdb)
|
|
@@Hello world
|
|
*stopped,reason="breakpoint-hit",disp="keep",bkptno="2",frame=@{
|
|
func="foo",args=[],file="hello.c",fullname="/home/foo/bar/hello.c",
|
|
line="13"@}
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
|
|
@subheading The @code{-exec-finish} Command
|
|
@findex -exec-finish
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-exec-finish [--reverse]
|
|
@end smallexample
|
|
|
|
Resumes the execution of the inferior program until the current
|
|
function is exited. Displays the results returned by the function.
|
|
If the @samp{--reverse} option is specified, resumes the reverse
|
|
execution of the inferior program until the point where current
|
|
function was called.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} command is @samp{finish}.
|
|
|
|
@subsubheading Example
|
|
|
|
Function returning @code{void}.
|
|
|
|
@smallexample
|
|
-exec-finish
|
|
^running
|
|
(gdb)
|
|
@@hello from foo
|
|
*stopped,reason="function-finished",frame=@{func="main",args=[],
|
|
file="hello.c",fullname="/home/foo/bar/hello.c",line="7"@}
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
Function returning other than @code{void}. The name of the internal
|
|
@value{GDBN} variable storing the result is printed, together with the
|
|
value itself.
|
|
|
|
@smallexample
|
|
-exec-finish
|
|
^running
|
|
(gdb)
|
|
*stopped,reason="function-finished",frame=@{addr="0x000107b0",func="foo",
|
|
args=[@{name="a",value="1"],@{name="b",value="9"@}@},
|
|
file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"@},
|
|
gdb-result-var="$1",return-value="0"
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
|
|
@subheading The @code{-exec-interrupt} Command
|
|
@findex -exec-interrupt
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-exec-interrupt [--all|--thread-group N]
|
|
@end smallexample
|
|
|
|
Interrupts the background execution of the target. Note how the token
|
|
associated with the stop message is the one for the execution command
|
|
that has been interrupted. The token for the interrupt itself only
|
|
appears in the @samp{^done} output. If the user is trying to
|
|
interrupt a non-running program, an error message will be printed.
|
|
|
|
Note that when asynchronous execution is enabled, this command is
|
|
asynchronous just like other execution commands. That is, first the
|
|
@samp{^done} response will be printed, and the target stop will be
|
|
reported after that using the @samp{*stopped} notification.
|
|
|
|
In non-stop mode, only the context thread is interrupted by default.
|
|
All threads (in all inferiors) will be interrupted if the
|
|
@samp{--all} option is specified. If the @samp{--thread-group}
|
|
option is specified, all threads in that group will be interrupted.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} command is @samp{interrupt}.
|
|
|
|
@subsubheading Example
|
|
|
|
@smallexample
|
|
(gdb)
|
|
111-exec-continue
|
|
111^running
|
|
|
|
(gdb)
|
|
222-exec-interrupt
|
|
222^done
|
|
(gdb)
|
|
111*stopped,signal-name="SIGINT",signal-meaning="Interrupt",
|
|
frame=@{addr="0x00010140",func="foo",args=[],file="try.c",
|
|
fullname="/home/foo/bar/try.c",line="13"@}
|
|
(gdb)
|
|
|
|
(gdb)
|
|
-exec-interrupt
|
|
^error,msg="mi_cmd_exec_interrupt: Inferior not executing."
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
@subheading The @code{-exec-jump} Command
|
|
@findex -exec-jump
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-exec-jump @var{location}
|
|
@end smallexample
|
|
|
|
Resumes execution of the inferior program at the location specified by
|
|
parameter. @xref{Specify Location}, for a description of the
|
|
different forms of @var{location}.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} command is @samp{jump}.
|
|
|
|
@subsubheading Example
|
|
|
|
@smallexample
|
|
-exec-jump foo.c:10
|
|
*running,thread-id="all"
|
|
^running
|
|
@end smallexample
|
|
|
|
|
|
@subheading The @code{-exec-next} Command
|
|
@findex -exec-next
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-exec-next [--reverse]
|
|
@end smallexample
|
|
|
|
Resumes execution of the inferior program, stopping when the beginning
|
|
of the next source line is reached.
|
|
|
|
If the @samp{--reverse} option is specified, resumes reverse execution
|
|
of the inferior program, stopping at the beginning of the previous
|
|
source line. If you issue this command on the first line of a
|
|
function, it will take you back to the caller of that function, to the
|
|
source line where the function was called.
|
|
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} command is @samp{next}.
|
|
|
|
@subsubheading Example
|
|
|
|
@smallexample
|
|
-exec-next
|
|
^running
|
|
(gdb)
|
|
*stopped,reason="end-stepping-range",line="8",file="hello.c"
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
|
|
@subheading The @code{-exec-next-instruction} Command
|
|
@findex -exec-next-instruction
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-exec-next-instruction [--reverse]
|
|
@end smallexample
|
|
|
|
Executes one machine instruction. If the instruction is a function
|
|
call, continues until the function returns. If the program stops at an
|
|
instruction in the middle of a source line, the address will be
|
|
printed as well.
|
|
|
|
If the @samp{--reverse} option is specified, resumes reverse execution
|
|
of the inferior program, stopping at the previous instruction. If the
|
|
previously executed instruction was a return from another function,
|
|
it will continue to execute in reverse until the call to that function
|
|
(from the current stack frame) is reached.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} command is @samp{nexti}.
|
|
|
|
@subsubheading Example
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-exec-next-instruction
|
|
^running
|
|
|
|
(gdb)
|
|
*stopped,reason="end-stepping-range",
|
|
addr="0x000100d4",line="5",file="hello.c"
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
|
|
@subheading The @code{-exec-return} Command
|
|
@findex -exec-return
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-exec-return
|
|
@end smallexample
|
|
|
|
Makes current function return immediately. Doesn't execute the inferior.
|
|
Displays the new current frame.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} command is @samp{return}.
|
|
|
|
@subsubheading Example
|
|
|
|
@smallexample
|
|
(gdb)
|
|
200-break-insert callee4
|
|
200^done,bkpt=@{number="1",addr="0x00010734",
|
|
file="../../../devo/gdb/testsuite/gdb.mi/basics.c",line="8"@}
|
|
(gdb)
|
|
000-exec-run
|
|
000^running
|
|
(gdb)
|
|
000*stopped,reason="breakpoint-hit",disp="keep",bkptno="1",
|
|
frame=@{func="callee4",args=[],
|
|
file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
|
|
fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="8"@}
|
|
(gdb)
|
|
205-break-delete
|
|
205^done
|
|
(gdb)
|
|
111-exec-return
|
|
111^done,frame=@{level="0",func="callee3",
|
|
args=[@{name="strarg",
|
|
value="0x11940 \"A string argument.\""@}],
|
|
file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
|
|
fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="18"@}
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
|
|
@subheading The @code{-exec-run} Command
|
|
@findex -exec-run
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-exec-run [--all | --thread-group N]
|
|
@end smallexample
|
|
|
|
Starts execution of the inferior from the beginning. The inferior
|
|
executes until either a breakpoint is encountered or the program
|
|
exits. In the latter case the output will include an exit code, if
|
|
the program has exited exceptionally.
|
|
|
|
When no option is specified, the current inferior is started. If the
|
|
@samp{--thread-group} option is specified, it should refer to a thread
|
|
group of type @samp{process}, and that thread group will be started.
|
|
If the @samp{--all} option is specified, then all inferiors will be started.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} command is @samp{run}.
|
|
|
|
@subsubheading Examples
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-break-insert main
|
|
^done,bkpt=@{number="1",addr="0x0001072c",file="recursive2.c",line="4"@}
|
|
(gdb)
|
|
-exec-run
|
|
^running
|
|
(gdb)
|
|
*stopped,reason="breakpoint-hit",disp="keep",bkptno="1",
|
|
frame=@{func="main",args=[],file="recursive2.c",
|
|
fullname="/home/foo/bar/recursive2.c",line="4"@}
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
@noindent
|
|
Program exited normally:
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-exec-run
|
|
^running
|
|
(gdb)
|
|
x = 55
|
|
*stopped,reason="exited-normally"
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
@noindent
|
|
Program exited exceptionally:
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-exec-run
|
|
^running
|
|
(gdb)
|
|
x = 55
|
|
*stopped,reason="exited",exit-code="01"
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
Another way the program can terminate is if it receives a signal such as
|
|
@code{SIGINT}. In this case, @sc{gdb/mi} displays this:
|
|
|
|
@smallexample
|
|
(gdb)
|
|
*stopped,reason="exited-signalled",signal-name="SIGINT",
|
|
signal-meaning="Interrupt"
|
|
@end smallexample
|
|
|
|
|
|
@c @subheading -exec-signal
|
|
|
|
|
|
@subheading The @code{-exec-step} Command
|
|
@findex -exec-step
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-exec-step [--reverse]
|
|
@end smallexample
|
|
|
|
Resumes execution of the inferior program, stopping when the beginning
|
|
of the next source line is reached, if the next source line is not a
|
|
function call. If it is, stop at the first instruction of the called
|
|
function. If the @samp{--reverse} option is specified, resumes reverse
|
|
execution of the inferior program, stopping at the beginning of the
|
|
previously executed source line.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} command is @samp{step}.
|
|
|
|
@subsubheading Example
|
|
|
|
Stepping into a function:
|
|
|
|
@smallexample
|
|
-exec-step
|
|
^running
|
|
(gdb)
|
|
*stopped,reason="end-stepping-range",
|
|
frame=@{func="foo",args=[@{name="a",value="10"@},
|
|
@{name="b",value="0"@}],file="recursive2.c",
|
|
fullname="/home/foo/bar/recursive2.c",line="11"@}
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
Regular stepping:
|
|
|
|
@smallexample
|
|
-exec-step
|
|
^running
|
|
(gdb)
|
|
*stopped,reason="end-stepping-range",line="14",file="recursive2.c"
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
|
|
@subheading The @code{-exec-step-instruction} Command
|
|
@findex -exec-step-instruction
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-exec-step-instruction [--reverse]
|
|
@end smallexample
|
|
|
|
Resumes the inferior which executes one machine instruction. If the
|
|
@samp{--reverse} option is specified, resumes reverse execution of the
|
|
inferior program, stopping at the previously executed instruction.
|
|
The output, once @value{GDBN} has stopped, will vary depending on
|
|
whether we have stopped in the middle of a source line or not. In the
|
|
former case, the address at which the program stopped will be printed
|
|
as well.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} command is @samp{stepi}.
|
|
|
|
@subsubheading Example
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-exec-step-instruction
|
|
^running
|
|
|
|
(gdb)
|
|
*stopped,reason="end-stepping-range",
|
|
frame=@{func="foo",args=[],file="try.c",
|
|
fullname="/home/foo/bar/try.c",line="10"@}
|
|
(gdb)
|
|
-exec-step-instruction
|
|
^running
|
|
|
|
(gdb)
|
|
*stopped,reason="end-stepping-range",
|
|
frame=@{addr="0x000100f4",func="foo",args=[],file="try.c",
|
|
fullname="/home/foo/bar/try.c",line="10"@}
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
|
|
@subheading The @code{-exec-until} Command
|
|
@findex -exec-until
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-exec-until [ @var{location} ]
|
|
@end smallexample
|
|
|
|
Executes the inferior until the @var{location} specified in the
|
|
argument is reached. If there is no argument, the inferior executes
|
|
until a source line greater than the current one is reached. The
|
|
reason for stopping in this case will be @samp{location-reached}.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} command is @samp{until}.
|
|
|
|
@subsubheading Example
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-exec-until recursive2.c:6
|
|
^running
|
|
(gdb)
|
|
x = 55
|
|
*stopped,reason="location-reached",frame=@{func="main",args=[],
|
|
file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="6"@}
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
@ignore
|
|
@subheading -file-clear
|
|
Is this going away????
|
|
@end ignore
|
|
|
|
@c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
@node GDB/MI Stack Manipulation
|
|
@section @sc{gdb/mi} Stack Manipulation Commands
|
|
|
|
|
|
@subheading The @code{-stack-info-frame} Command
|
|
@findex -stack-info-frame
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-stack-info-frame
|
|
@end smallexample
|
|
|
|
Get info on the selected frame.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} command is @samp{info frame} or @samp{frame}
|
|
(without arguments).
|
|
|
|
@subsubheading Example
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-stack-info-frame
|
|
^done,frame=@{level="1",addr="0x0001076c",func="callee3",
|
|
file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
|
|
fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="17"@}
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
@subheading The @code{-stack-info-depth} Command
|
|
@findex -stack-info-depth
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-stack-info-depth [ @var{max-depth} ]
|
|
@end smallexample
|
|
|
|
Return the depth of the stack. If the integer argument @var{max-depth}
|
|
is specified, do not count beyond @var{max-depth} frames.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
There's no equivalent @value{GDBN} command.
|
|
|
|
@subsubheading Example
|
|
|
|
For a stack with frame levels 0 through 11:
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-stack-info-depth
|
|
^done,depth="12"
|
|
(gdb)
|
|
-stack-info-depth 4
|
|
^done,depth="4"
|
|
(gdb)
|
|
-stack-info-depth 12
|
|
^done,depth="12"
|
|
(gdb)
|
|
-stack-info-depth 11
|
|
^done,depth="11"
|
|
(gdb)
|
|
-stack-info-depth 13
|
|
^done,depth="12"
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
@subheading The @code{-stack-list-arguments} Command
|
|
@findex -stack-list-arguments
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-stack-list-arguments @var{print-values}
|
|
[ @var{low-frame} @var{high-frame} ]
|
|
@end smallexample
|
|
|
|
Display a list of the arguments for the frames between @var{low-frame}
|
|
and @var{high-frame} (inclusive). If @var{low-frame} and
|
|
@var{high-frame} are not provided, list the arguments for the whole
|
|
call stack. If the two arguments are equal, show the single frame
|
|
at the corresponding level. It is an error if @var{low-frame} is
|
|
larger than the actual number of frames. On the other hand,
|
|
@var{high-frame} may be larger than the actual number of frames, in
|
|
which case only existing frames will be returned.
|
|
|
|
If @var{print-values} is 0 or @code{--no-values}, print only the names of
|
|
the variables; if it is 1 or @code{--all-values}, print also their
|
|
values; and if it is 2 or @code{--simple-values}, print the name,
|
|
type and value for simple data types, and the name and type for arrays,
|
|
structures and unions.
|
|
|
|
Use of this command to obtain arguments in a single frame is
|
|
deprecated in favor of the @samp{-stack-list-variables} command.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
@value{GDBN} does not have an equivalent command. @code{gdbtk} has a
|
|
@samp{gdb_get_args} command which partially overlaps with the
|
|
functionality of @samp{-stack-list-arguments}.
|
|
|
|
@subsubheading Example
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-stack-list-frames
|
|
^done,
|
|
stack=[
|
|
frame=@{level="0",addr="0x00010734",func="callee4",
|
|
file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
|
|
fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="8"@},
|
|
frame=@{level="1",addr="0x0001076c",func="callee3",
|
|
file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
|
|
fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="17"@},
|
|
frame=@{level="2",addr="0x0001078c",func="callee2",
|
|
file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
|
|
fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="22"@},
|
|
frame=@{level="3",addr="0x000107b4",func="callee1",
|
|
file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
|
|
fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="27"@},
|
|
frame=@{level="4",addr="0x000107e0",func="main",
|
|
file="../../../devo/gdb/testsuite/gdb.mi/basics.c",
|
|
fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="32"@}]
|
|
(gdb)
|
|
-stack-list-arguments 0
|
|
^done,
|
|
stack-args=[
|
|
frame=@{level="0",args=[]@},
|
|
frame=@{level="1",args=[name="strarg"]@},
|
|
frame=@{level="2",args=[name="intarg",name="strarg"]@},
|
|
frame=@{level="3",args=[name="intarg",name="strarg",name="fltarg"]@},
|
|
frame=@{level="4",args=[]@}]
|
|
(gdb)
|
|
-stack-list-arguments 1
|
|
^done,
|
|
stack-args=[
|
|
frame=@{level="0",args=[]@},
|
|
frame=@{level="1",
|
|
args=[@{name="strarg",value="0x11940 \"A string argument.\""@}]@},
|
|
frame=@{level="2",args=[
|
|
@{name="intarg",value="2"@},
|
|
@{name="strarg",value="0x11940 \"A string argument.\""@}]@},
|
|
@{frame=@{level="3",args=[
|
|
@{name="intarg",value="2"@},
|
|
@{name="strarg",value="0x11940 \"A string argument.\""@},
|
|
@{name="fltarg",value="3.5"@}]@},
|
|
frame=@{level="4",args=[]@}]
|
|
(gdb)
|
|
-stack-list-arguments 0 2 2
|
|
^done,stack-args=[frame=@{level="2",args=[name="intarg",name="strarg"]@}]
|
|
(gdb)
|
|
-stack-list-arguments 1 2 2
|
|
^done,stack-args=[frame=@{level="2",
|
|
args=[@{name="intarg",value="2"@},
|
|
@{name="strarg",value="0x11940 \"A string argument.\""@}]@}]
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
@c @subheading -stack-list-exception-handlers
|
|
|
|
|
|
@subheading The @code{-stack-list-frames} Command
|
|
@findex -stack-list-frames
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-stack-list-frames [ @var{low-frame} @var{high-frame} ]
|
|
@end smallexample
|
|
|
|
List the frames currently on the stack. For each frame it displays the
|
|
following info:
|
|
|
|
@table @samp
|
|
@item @var{level}
|
|
The frame number, 0 being the topmost frame, i.e., the innermost function.
|
|
@item @var{addr}
|
|
The @code{$pc} value for that frame.
|
|
@item @var{func}
|
|
Function name.
|
|
@item @var{file}
|
|
File name of the source file where the function lives.
|
|
@item @var{fullname}
|
|
The full file name of the source file where the function lives.
|
|
@item @var{line}
|
|
Line number corresponding to the @code{$pc}.
|
|
@item @var{from}
|
|
The shared library where this function is defined. This is only given
|
|
if the frame's function is not known.
|
|
@end table
|
|
|
|
If invoked without arguments, this command prints a backtrace for the
|
|
whole stack. If given two integer arguments, it shows the frames whose
|
|
levels are between the two arguments (inclusive). If the two arguments
|
|
are equal, it shows the single frame at the corresponding level. It is
|
|
an error if @var{low-frame} is larger than the actual number of
|
|
frames. On the other hand, @var{high-frame} may be larger than the
|
|
actual number of frames, in which case only existing frames will be returned.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} commands are @samp{backtrace} and @samp{where}.
|
|
|
|
@subsubheading Example
|
|
|
|
Full stack backtrace:
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-stack-list-frames
|
|
^done,stack=
|
|
[frame=@{level="0",addr="0x0001076c",func="foo",
|
|
file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="11"@},
|
|
frame=@{level="1",addr="0x000107a4",func="foo",
|
|
file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"@},
|
|
frame=@{level="2",addr="0x000107a4",func="foo",
|
|
file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"@},
|
|
frame=@{level="3",addr="0x000107a4",func="foo",
|
|
file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"@},
|
|
frame=@{level="4",addr="0x000107a4",func="foo",
|
|
file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"@},
|
|
frame=@{level="5",addr="0x000107a4",func="foo",
|
|
file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"@},
|
|
frame=@{level="6",addr="0x000107a4",func="foo",
|
|
file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"@},
|
|
frame=@{level="7",addr="0x000107a4",func="foo",
|
|
file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"@},
|
|
frame=@{level="8",addr="0x000107a4",func="foo",
|
|
file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"@},
|
|
frame=@{level="9",addr="0x000107a4",func="foo",
|
|
file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"@},
|
|
frame=@{level="10",addr="0x000107a4",func="foo",
|
|
file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"@},
|
|
frame=@{level="11",addr="0x00010738",func="main",
|
|
file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="4"@}]
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
Show frames between @var{low_frame} and @var{high_frame}:
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-stack-list-frames 3 5
|
|
^done,stack=
|
|
[frame=@{level="3",addr="0x000107a4",func="foo",
|
|
file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"@},
|
|
frame=@{level="4",addr="0x000107a4",func="foo",
|
|
file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"@},
|
|
frame=@{level="5",addr="0x000107a4",func="foo",
|
|
file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"@}]
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
Show a single frame:
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-stack-list-frames 3 3
|
|
^done,stack=
|
|
[frame=@{level="3",addr="0x000107a4",func="foo",
|
|
file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"@}]
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
|
|
@subheading The @code{-stack-list-locals} Command
|
|
@findex -stack-list-locals
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-stack-list-locals @var{print-values}
|
|
@end smallexample
|
|
|
|
Display the local variable names for the selected frame. If
|
|
@var{print-values} is 0 or @code{--no-values}, print only the names of
|
|
the variables; if it is 1 or @code{--all-values}, print also their
|
|
values; and if it is 2 or @code{--simple-values}, print the name,
|
|
type and value for simple data types, and the name and type for arrays,
|
|
structures and unions. In this last case, a frontend can immediately
|
|
display the value of simple data types and create variable objects for
|
|
other data types when the user wishes to explore their values in
|
|
more detail.
|
|
|
|
This command is deprecated in favor of the
|
|
@samp{-stack-list-variables} command.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
@samp{info locals} in @value{GDBN}, @samp{gdb_get_locals} in @code{gdbtk}.
|
|
|
|
@subsubheading Example
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-stack-list-locals 0
|
|
^done,locals=[name="A",name="B",name="C"]
|
|
(gdb)
|
|
-stack-list-locals --all-values
|
|
^done,locals=[@{name="A",value="1"@},@{name="B",value="2"@},
|
|
@{name="C",value="@{1, 2, 3@}"@}]
|
|
-stack-list-locals --simple-values
|
|
^done,locals=[@{name="A",type="int",value="1"@},
|
|
@{name="B",type="int",value="2"@},@{name="C",type="int [3]"@}]
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
@subheading The @code{-stack-list-variables} Command
|
|
@findex -stack-list-variables
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-stack-list-variables @var{print-values}
|
|
@end smallexample
|
|
|
|
Display the names of local variables and function arguments for the selected frame. If
|
|
@var{print-values} is 0 or @code{--no-values}, print only the names of
|
|
the variables; if it is 1 or @code{--all-values}, print also their
|
|
values; and if it is 2 or @code{--simple-values}, print the name,
|
|
type and value for simple data types, and the name and type for arrays,
|
|
structures and unions.
|
|
|
|
@subsubheading Example
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-stack-list-variables --thread 1 --frame 0 --all-values
|
|
^done,variables=[@{name="x",value="11"@},@{name="s",value="@{a = 1, b = 2@}"@}]
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
|
|
@subheading The @code{-stack-select-frame} Command
|
|
@findex -stack-select-frame
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-stack-select-frame @var{framenum}
|
|
@end smallexample
|
|
|
|
Change the selected frame. Select a different frame @var{framenum} on
|
|
the stack.
|
|
|
|
This command in deprecated in favor of passing the @samp{--frame}
|
|
option to every command.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} commands are @samp{frame}, @samp{up},
|
|
@samp{down}, @samp{select-frame}, @samp{up-silent}, and @samp{down-silent}.
|
|
|
|
@subsubheading Example
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-stack-select-frame 2
|
|
^done
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
@c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
@node GDB/MI Variable Objects
|
|
@section @sc{gdb/mi} Variable Objects
|
|
|
|
@ignore
|
|
|
|
@subheading Motivation for Variable Objects in @sc{gdb/mi}
|
|
|
|
For the implementation of a variable debugger window (locals, watched
|
|
expressions, etc.), we are proposing the adaptation of the existing code
|
|
used by @code{Insight}.
|
|
|
|
The two main reasons for that are:
|
|
|
|
@enumerate 1
|
|
@item
|
|
It has been proven in practice (it is already on its second generation).
|
|
|
|
@item
|
|
It will shorten development time (needless to say how important it is
|
|
now).
|
|
@end enumerate
|
|
|
|
The original interface was designed to be used by Tcl code, so it was
|
|
slightly changed so it could be used through @sc{gdb/mi}. This section
|
|
describes the @sc{gdb/mi} operations that will be available and gives some
|
|
hints about their use.
|
|
|
|
@emph{Note}: In addition to the set of operations described here, we
|
|
expect the @sc{gui} implementation of a variable window to require, at
|
|
least, the following operations:
|
|
|
|
@itemize @bullet
|
|
@item @code{-gdb-show} @code{output-radix}
|
|
@item @code{-stack-list-arguments}
|
|
@item @code{-stack-list-locals}
|
|
@item @code{-stack-select-frame}
|
|
@end itemize
|
|
|
|
@end ignore
|
|
|
|
@subheading Introduction to Variable Objects
|
|
|
|
@cindex variable objects in @sc{gdb/mi}
|
|
|
|
Variable objects are "object-oriented" MI interface for examining and
|
|
changing values of expressions. Unlike some other MI interfaces that
|
|
work with expressions, variable objects are specifically designed for
|
|
simple and efficient presentation in the frontend. A variable object
|
|
is identified by string name. When a variable object is created, the
|
|
frontend specifies the expression for that variable object. The
|
|
expression can be a simple variable, or it can be an arbitrary complex
|
|
expression, and can even involve CPU registers. After creating a
|
|
variable object, the frontend can invoke other variable object
|
|
operations---for example to obtain or change the value of a variable
|
|
object, or to change display format.
|
|
|
|
Variable objects have hierarchical tree structure. Any variable object
|
|
that corresponds to a composite type, such as structure in C, has
|
|
a number of child variable objects, for example corresponding to each
|
|
element of a structure. A child variable object can itself have
|
|
children, recursively. Recursion ends when we reach
|
|
leaf variable objects, which always have built-in types. Child variable
|
|
objects are created only by explicit request, so if a frontend
|
|
is not interested in the children of a particular variable object, no
|
|
child will be created.
|
|
|
|
For a leaf variable object it is possible to obtain its value as a
|
|
string, or set the value from a string. String value can be also
|
|
obtained for a non-leaf variable object, but it's generally a string
|
|
that only indicates the type of the object, and does not list its
|
|
contents. Assignment to a non-leaf variable object is not allowed.
|
|
|
|
A frontend does not need to read the values of all variable objects each time
|
|
the program stops. Instead, MI provides an update command that lists all
|
|
variable objects whose values has changed since the last update
|
|
operation. This considerably reduces the amount of data that must
|
|
be transferred to the frontend. As noted above, children variable
|
|
objects are created on demand, and only leaf variable objects have a
|
|
real value. As result, gdb will read target memory only for leaf
|
|
variables that frontend has created.
|
|
|
|
The automatic update is not always desirable. For example, a frontend
|
|
might want to keep a value of some expression for future reference,
|
|
and never update it. For another example, fetching memory is
|
|
relatively slow for embedded targets, so a frontend might want
|
|
to disable automatic update for the variables that are either not
|
|
visible on the screen, or ``closed''. This is possible using so
|
|
called ``frozen variable objects''. Such variable objects are never
|
|
implicitly updated.
|
|
|
|
Variable objects can be either @dfn{fixed} or @dfn{floating}. For the
|
|
fixed variable object, the expression is parsed when the variable
|
|
object is created, including associating identifiers to specific
|
|
variables. The meaning of expression never changes. For a floating
|
|
variable object the values of variables whose names appear in the
|
|
expressions are re-evaluated every time in the context of the current
|
|
frame. Consider this example:
|
|
|
|
@smallexample
|
|
void do_work(...)
|
|
@{
|
|
struct work_state state;
|
|
|
|
if (...)
|
|
do_work(...);
|
|
@}
|
|
@end smallexample
|
|
|
|
If a fixed variable object for the @code{state} variable is created in
|
|
this function, and we enter the recursive call, the variable
|
|
object will report the value of @code{state} in the top-level
|
|
@code{do_work} invocation. On the other hand, a floating variable
|
|
object will report the value of @code{state} in the current frame.
|
|
|
|
If an expression specified when creating a fixed variable object
|
|
refers to a local variable, the variable object becomes bound to the
|
|
thread and frame in which the variable object is created. When such
|
|
variable object is updated, @value{GDBN} makes sure that the
|
|
thread/frame combination the variable object is bound to still exists,
|
|
and re-evaluates the variable object in context of that thread/frame.
|
|
|
|
The following is the complete set of @sc{gdb/mi} operations defined to
|
|
access this functionality:
|
|
|
|
@multitable @columnfractions .4 .6
|
|
@item @strong{Operation}
|
|
@tab @strong{Description}
|
|
|
|
@item @code{-enable-pretty-printing}
|
|
@tab enable Python-based pretty-printing
|
|
@item @code{-var-create}
|
|
@tab create a variable object
|
|
@item @code{-var-delete}
|
|
@tab delete the variable object and/or its children
|
|
@item @code{-var-set-format}
|
|
@tab set the display format of this variable
|
|
@item @code{-var-show-format}
|
|
@tab show the display format of this variable
|
|
@item @code{-var-info-num-children}
|
|
@tab tells how many children this object has
|
|
@item @code{-var-list-children}
|
|
@tab return a list of the object's children
|
|
@item @code{-var-info-type}
|
|
@tab show the type of this variable object
|
|
@item @code{-var-info-expression}
|
|
@tab print parent-relative expression that this variable object represents
|
|
@item @code{-var-info-path-expression}
|
|
@tab print full expression that this variable object represents
|
|
@item @code{-var-show-attributes}
|
|
@tab is this variable editable? does it exist here?
|
|
@item @code{-var-evaluate-expression}
|
|
@tab get the value of this variable
|
|
@item @code{-var-assign}
|
|
@tab set the value of this variable
|
|
@item @code{-var-update}
|
|
@tab update the variable and its children
|
|
@item @code{-var-set-frozen}
|
|
@tab set frozeness attribute
|
|
@item @code{-var-set-update-range}
|
|
@tab set range of children to display on update
|
|
@end multitable
|
|
|
|
In the next subsection we describe each operation in detail and suggest
|
|
how it can be used.
|
|
|
|
@subheading Description And Use of Operations on Variable Objects
|
|
|
|
@subheading The @code{-enable-pretty-printing} Command
|
|
@findex -enable-pretty-printing
|
|
|
|
@smallexample
|
|
-enable-pretty-printing
|
|
@end smallexample
|
|
|
|
@value{GDBN} allows Python-based visualizers to affect the output of the
|
|
MI variable object commands. However, because there was no way to
|
|
implement this in a fully backward-compatible way, a front end must
|
|
request that this functionality be enabled.
|
|
|
|
Once enabled, this feature cannot be disabled.
|
|
|
|
Note that if Python support has not been compiled into @value{GDBN},
|
|
this command will still succeed (and do nothing).
|
|
|
|
This feature is currently (as of @value{GDBN} 7.0) experimental, and
|
|
may work differently in future versions of @value{GDBN}.
|
|
|
|
@subheading The @code{-var-create} Command
|
|
@findex -var-create
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-var-create @{@var{name} | "-"@}
|
|
@{@var{frame-addr} | "*" | "@@"@} @var{expression}
|
|
@end smallexample
|
|
|
|
This operation creates a variable object, which allows the monitoring of
|
|
a variable, the result of an expression, a memory cell or a CPU
|
|
register.
|
|
|
|
The @var{name} parameter is the string by which the object can be
|
|
referenced. It must be unique. If @samp{-} is specified, the varobj
|
|
system will generate a string ``varNNNNNN'' automatically. It will be
|
|
unique provided that one does not specify @var{name} of that format.
|
|
The command fails if a duplicate name is found.
|
|
|
|
The frame under which the expression should be evaluated can be
|
|
specified by @var{frame-addr}. A @samp{*} indicates that the current
|
|
frame should be used. A @samp{@@} indicates that a floating variable
|
|
object must be created.
|
|
|
|
@var{expression} is any expression valid on the current language set (must not
|
|
begin with a @samp{*}), or one of the following:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
@samp{*@var{addr}}, where @var{addr} is the address of a memory cell
|
|
|
|
@item
|
|
@samp{*@var{addr}-@var{addr}} --- a memory address range (TBD)
|
|
|
|
@item
|
|
@samp{$@var{regname}} --- a CPU register name
|
|
@end itemize
|
|
|
|
@cindex dynamic varobj
|
|
A varobj's contents may be provided by a Python-based pretty-printer. In this
|
|
case the varobj is known as a @dfn{dynamic varobj}. Dynamic varobjs
|
|
have slightly different semantics in some cases. If the
|
|
@code{-enable-pretty-printing} command is not sent, then @value{GDBN}
|
|
will never create a dynamic varobj. This ensures backward
|
|
compatibility for existing clients.
|
|
|
|
@subsubheading Result
|
|
|
|
This operation returns attributes of the newly-created varobj. These
|
|
are:
|
|
|
|
@table @samp
|
|
@item name
|
|
The name of the varobj.
|
|
|
|
@item numchild
|
|
The number of children of the varobj. This number is not necessarily
|
|
reliable for a dynamic varobj. Instead, you must examine the
|
|
@samp{has_more} attribute.
|
|
|
|
@item value
|
|
The varobj's scalar value. For a varobj whose type is some sort of
|
|
aggregate (e.g., a @code{struct}), or for a dynamic varobj, this value
|
|
will not be interesting.
|
|
|
|
@item type
|
|
The varobj's type. This is a string representation of the type, as
|
|
would be printed by the @value{GDBN} CLI. If @samp{print object}
|
|
(@pxref{Print Settings, set print object}) is set to @code{on}, the
|
|
@emph{actual} (derived) type of the object is shown rather than the
|
|
@emph{declared} one.
|
|
|
|
@item thread-id
|
|
If a variable object is bound to a specific thread, then this is the
|
|
thread's identifier.
|
|
|
|
@item has_more
|
|
For a dynamic varobj, this indicates whether there appear to be any
|
|
children available. For a non-dynamic varobj, this will be 0.
|
|
|
|
@item dynamic
|
|
This attribute will be present and have the value @samp{1} if the
|
|
varobj is a dynamic varobj. If the varobj is not a dynamic varobj,
|
|
then this attribute will not be present.
|
|
|
|
@item displayhint
|
|
A dynamic varobj can supply a display hint to the front end. The
|
|
value comes directly from the Python pretty-printer object's
|
|
@code{display_hint} method. @xref{Pretty Printing API}.
|
|
@end table
|
|
|
|
Typical output will look like this:
|
|
|
|
@smallexample
|
|
name="@var{name}",numchild="@var{N}",type="@var{type}",thread-id="@var{M}",
|
|
has_more="@var{has_more}"
|
|
@end smallexample
|
|
|
|
|
|
@subheading The @code{-var-delete} Command
|
|
@findex -var-delete
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-var-delete [ -c ] @var{name}
|
|
@end smallexample
|
|
|
|
Deletes a previously created variable object and all of its children.
|
|
With the @samp{-c} option, just deletes the children.
|
|
|
|
Returns an error if the object @var{name} is not found.
|
|
|
|
|
|
@subheading The @code{-var-set-format} Command
|
|
@findex -var-set-format
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-var-set-format @var{name} @var{format-spec}
|
|
@end smallexample
|
|
|
|
Sets the output format for the value of the object @var{name} to be
|
|
@var{format-spec}.
|
|
|
|
@anchor{-var-set-format}
|
|
The syntax for the @var{format-spec} is as follows:
|
|
|
|
@smallexample
|
|
@var{format-spec} @expansion{}
|
|
@{binary | decimal | hexadecimal | octal | natural@}
|
|
@end smallexample
|
|
|
|
The natural format is the default format choosen automatically
|
|
based on the variable type (like decimal for an @code{int}, hex
|
|
for pointers, etc.).
|
|
|
|
For a variable with children, the format is set only on the
|
|
variable itself, and the children are not affected.
|
|
|
|
@subheading The @code{-var-show-format} Command
|
|
@findex -var-show-format
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-var-show-format @var{name}
|
|
@end smallexample
|
|
|
|
Returns the format used to display the value of the object @var{name}.
|
|
|
|
@smallexample
|
|
@var{format} @expansion{}
|
|
@var{format-spec}
|
|
@end smallexample
|
|
|
|
|
|
@subheading The @code{-var-info-num-children} Command
|
|
@findex -var-info-num-children
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-var-info-num-children @var{name}
|
|
@end smallexample
|
|
|
|
Returns the number of children of a variable object @var{name}:
|
|
|
|
@smallexample
|
|
numchild=@var{n}
|
|
@end smallexample
|
|
|
|
Note that this number is not completely reliable for a dynamic varobj.
|
|
It will return the current number of children, but more children may
|
|
be available.
|
|
|
|
|
|
@subheading The @code{-var-list-children} Command
|
|
@findex -var-list-children
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-var-list-children [@var{print-values}] @var{name} [@var{from} @var{to}]
|
|
@end smallexample
|
|
@anchor{-var-list-children}
|
|
|
|
Return a list of the children of the specified variable object and
|
|
create variable objects for them, if they do not already exist. With
|
|
a single argument or if @var{print-values} has a value of 0 or
|
|
@code{--no-values}, print only the names of the variables; if
|
|
@var{print-values} is 1 or @code{--all-values}, also print their
|
|
values; and if it is 2 or @code{--simple-values} print the name and
|
|
value for simple data types and just the name for arrays, structures
|
|
and unions.
|
|
|
|
@var{from} and @var{to}, if specified, indicate the range of children
|
|
to report. If @var{from} or @var{to} is less than zero, the range is
|
|
reset and all children will be reported. Otherwise, children starting
|
|
at @var{from} (zero-based) and up to and excluding @var{to} will be
|
|
reported.
|
|
|
|
If a child range is requested, it will only affect the current call to
|
|
@code{-var-list-children}, but not future calls to @code{-var-update}.
|
|
For this, you must instead use @code{-var-set-update-range}. The
|
|
intent of this approach is to enable a front end to implement any
|
|
update approach it likes; for example, scrolling a view may cause the
|
|
front end to request more children with @code{-var-list-children}, and
|
|
then the front end could call @code{-var-set-update-range} with a
|
|
different range to ensure that future updates are restricted to just
|
|
the visible items.
|
|
|
|
For each child the following results are returned:
|
|
|
|
@table @var
|
|
|
|
@item name
|
|
Name of the variable object created for this child.
|
|
|
|
@item exp
|
|
The expression to be shown to the user by the front end to designate this child.
|
|
For example this may be the name of a structure member.
|
|
|
|
For a dynamic varobj, this value cannot be used to form an
|
|
expression. There is no way to do this at all with a dynamic varobj.
|
|
|
|
For C/C@t{++} structures there are several pseudo children returned to
|
|
designate access qualifiers. For these pseudo children @var{exp} is
|
|
@samp{public}, @samp{private}, or @samp{protected}. In this case the
|
|
type and value are not present.
|
|
|
|
A dynamic varobj will not report the access qualifying
|
|
pseudo-children, regardless of the language. This information is not
|
|
available at all with a dynamic varobj.
|
|
|
|
@item numchild
|
|
Number of children this child has. For a dynamic varobj, this will be
|
|
0.
|
|
|
|
@item type
|
|
The type of the child. If @samp{print object}
|
|
(@pxref{Print Settings, set print object}) is set to @code{on}, the
|
|
@emph{actual} (derived) type of the object is shown rather than the
|
|
@emph{declared} one.
|
|
|
|
@item value
|
|
If values were requested, this is the value.
|
|
|
|
@item thread-id
|
|
If this variable object is associated with a thread, this is the thread id.
|
|
Otherwise this result is not present.
|
|
|
|
@item frozen
|
|
If the variable object is frozen, this variable will be present with a value of 1.
|
|
@end table
|
|
|
|
The result may have its own attributes:
|
|
|
|
@table @samp
|
|
@item displayhint
|
|
A dynamic varobj can supply a display hint to the front end. The
|
|
value comes directly from the Python pretty-printer object's
|
|
@code{display_hint} method. @xref{Pretty Printing API}.
|
|
|
|
@item has_more
|
|
This is an integer attribute which is nonzero if there are children
|
|
remaining after the end of the selected range.
|
|
@end table
|
|
|
|
@subsubheading Example
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-var-list-children n
|
|
^done,numchild=@var{n},children=[child=@{name=@var{name},exp=@var{exp},
|
|
numchild=@var{n},type=@var{type}@},@r{(repeats N times)}]
|
|
(gdb)
|
|
-var-list-children --all-values n
|
|
^done,numchild=@var{n},children=[child=@{name=@var{name},exp=@var{exp},
|
|
numchild=@var{n},value=@var{value},type=@var{type}@},@r{(repeats N times)}]
|
|
@end smallexample
|
|
|
|
|
|
@subheading The @code{-var-info-type} Command
|
|
@findex -var-info-type
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-var-info-type @var{name}
|
|
@end smallexample
|
|
|
|
Returns the type of the specified variable @var{name}. The type is
|
|
returned as a string in the same format as it is output by the
|
|
@value{GDBN} CLI:
|
|
|
|
@smallexample
|
|
type=@var{typename}
|
|
@end smallexample
|
|
|
|
|
|
@subheading The @code{-var-info-expression} Command
|
|
@findex -var-info-expression
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-var-info-expression @var{name}
|
|
@end smallexample
|
|
|
|
Returns a string that is suitable for presenting this
|
|
variable object in user interface. The string is generally
|
|
not valid expression in the current language, and cannot be evaluated.
|
|
|
|
For example, if @code{a} is an array, and variable object
|
|
@code{A} was created for @code{a}, then we'll get this output:
|
|
|
|
@smallexample
|
|
(gdb) -var-info-expression A.1
|
|
^done,lang="C",exp="1"
|
|
@end smallexample
|
|
|
|
@noindent
|
|
Here, the values of @code{lang} can be @code{@{"C" | "C++" | "Java"@}}.
|
|
|
|
Note that the output of the @code{-var-list-children} command also
|
|
includes those expressions, so the @code{-var-info-expression} command
|
|
is of limited use.
|
|
|
|
@subheading The @code{-var-info-path-expression} Command
|
|
@findex -var-info-path-expression
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-var-info-path-expression @var{name}
|
|
@end smallexample
|
|
|
|
Returns an expression that can be evaluated in the current
|
|
context and will yield the same value that a variable object has.
|
|
Compare this with the @code{-var-info-expression} command, which
|
|
result can be used only for UI presentation. Typical use of
|
|
the @code{-var-info-path-expression} command is creating a
|
|
watchpoint from a variable object.
|
|
|
|
This command is currently not valid for children of a dynamic varobj,
|
|
and will give an error when invoked on one.
|
|
|
|
For example, suppose @code{C} is a C@t{++} class, derived from class
|
|
@code{Base}, and that the @code{Base} class has a member called
|
|
@code{m_size}. Assume a variable @code{c} is has the type of
|
|
@code{C} and a variable object @code{C} was created for variable
|
|
@code{c}. Then, we'll get this output:
|
|
@smallexample
|
|
(gdb) -var-info-path-expression C.Base.public.m_size
|
|
^done,path_expr=((Base)c).m_size)
|
|
@end smallexample
|
|
|
|
@subheading The @code{-var-show-attributes} Command
|
|
@findex -var-show-attributes
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-var-show-attributes @var{name}
|
|
@end smallexample
|
|
|
|
List attributes of the specified variable object @var{name}:
|
|
|
|
@smallexample
|
|
status=@var{attr} [ ( ,@var{attr} )* ]
|
|
@end smallexample
|
|
|
|
@noindent
|
|
where @var{attr} is @code{@{ @{ editable | noneditable @} | TBD @}}.
|
|
|
|
@subheading The @code{-var-evaluate-expression} Command
|
|
@findex -var-evaluate-expression
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-var-evaluate-expression [-f @var{format-spec}] @var{name}
|
|
@end smallexample
|
|
|
|
Evaluates the expression that is represented by the specified variable
|
|
object and returns its value as a string. The format of the string
|
|
can be specified with the @samp{-f} option. The possible values of
|
|
this option are the same as for @code{-var-set-format}
|
|
(@pxref{-var-set-format}). If the @samp{-f} option is not specified,
|
|
the current display format will be used. The current display format
|
|
can be changed using the @code{-var-set-format} command.
|
|
|
|
@smallexample
|
|
value=@var{value}
|
|
@end smallexample
|
|
|
|
Note that one must invoke @code{-var-list-children} for a variable
|
|
before the value of a child variable can be evaluated.
|
|
|
|
@subheading The @code{-var-assign} Command
|
|
@findex -var-assign
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-var-assign @var{name} @var{expression}
|
|
@end smallexample
|
|
|
|
Assigns the value of @var{expression} to the variable object specified
|
|
by @var{name}. The object must be @samp{editable}. If the variable's
|
|
value is altered by the assign, the variable will show up in any
|
|
subsequent @code{-var-update} list.
|
|
|
|
@subsubheading Example
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-var-assign var1 3
|
|
^done,value="3"
|
|
(gdb)
|
|
-var-update *
|
|
^done,changelist=[@{name="var1",in_scope="true",type_changed="false"@}]
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
@subheading The @code{-var-update} Command
|
|
@findex -var-update
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-var-update [@var{print-values}] @{@var{name} | "*"@}
|
|
@end smallexample
|
|
|
|
Reevaluate the expressions corresponding to the variable object
|
|
@var{name} and all its direct and indirect children, and return the
|
|
list of variable objects whose values have changed; @var{name} must
|
|
be a root variable object. Here, ``changed'' means that the result of
|
|
@code{-var-evaluate-expression} before and after the
|
|
@code{-var-update} is different. If @samp{*} is used as the variable
|
|
object names, all existing variable objects are updated, except
|
|
for frozen ones (@pxref{-var-set-frozen}). The option
|
|
@var{print-values} determines whether both names and values, or just
|
|
names are printed. The possible values of this option are the same
|
|
as for @code{-var-list-children} (@pxref{-var-list-children}). It is
|
|
recommended to use the @samp{--all-values} option, to reduce the
|
|
number of MI commands needed on each program stop.
|
|
|
|
With the @samp{*} parameter, if a variable object is bound to a
|
|
currently running thread, it will not be updated, without any
|
|
diagnostic.
|
|
|
|
If @code{-var-set-update-range} was previously used on a varobj, then
|
|
only the selected range of children will be reported.
|
|
|
|
@code{-var-update} reports all the changed varobjs in a tuple named
|
|
@samp{changelist}.
|
|
|
|
Each item in the change list is itself a tuple holding:
|
|
|
|
@table @samp
|
|
@item name
|
|
The name of the varobj.
|
|
|
|
@item value
|
|
If values were requested for this update, then this field will be
|
|
present and will hold the value of the varobj.
|
|
|
|
@item in_scope
|
|
@anchor{-var-update}
|
|
This field is a string which may take one of three values:
|
|
|
|
@table @code
|
|
@item "true"
|
|
The variable object's current value is valid.
|
|
|
|
@item "false"
|
|
The variable object does not currently hold a valid value but it may
|
|
hold one in the future if its associated expression comes back into
|
|
scope.
|
|
|
|
@item "invalid"
|
|
The variable object no longer holds a valid value.
|
|
This can occur when the executable file being debugged has changed,
|
|
either through recompilation or by using the @value{GDBN} @code{file}
|
|
command. The front end should normally choose to delete these variable
|
|
objects.
|
|
@end table
|
|
|
|
In the future new values may be added to this list so the front should
|
|
be prepared for this possibility. @xref{GDB/MI Development and Front Ends, ,@sc{GDB/MI} Development and Front Ends}.
|
|
|
|
@item type_changed
|
|
This is only present if the varobj is still valid. If the type
|
|
changed, then this will be the string @samp{true}; otherwise it will
|
|
be @samp{false}.
|
|
|
|
When a varobj's type changes, its children are also likely to have
|
|
become incorrect. Therefore, the varobj's children are automatically
|
|
deleted when this attribute is @samp{true}. Also, the varobj's update
|
|
range, when set using the @code{-var-set-update-range} command, is
|
|
unset.
|
|
|
|
@item new_type
|
|
If the varobj's type changed, then this field will be present and will
|
|
hold the new type.
|
|
|
|
@item new_num_children
|
|
For a dynamic varobj, if the number of children changed, or if the
|
|
type changed, this will be the new number of children.
|
|
|
|
The @samp{numchild} field in other varobj responses is generally not
|
|
valid for a dynamic varobj -- it will show the number of children that
|
|
@value{GDBN} knows about, but because dynamic varobjs lazily
|
|
instantiate their children, this will not reflect the number of
|
|
children which may be available.
|
|
|
|
The @samp{new_num_children} attribute only reports changes to the
|
|
number of children known by @value{GDBN}. This is the only way to
|
|
detect whether an update has removed children (which necessarily can
|
|
only happen at the end of the update range).
|
|
|
|
@item displayhint
|
|
The display hint, if any.
|
|
|
|
@item has_more
|
|
This is an integer value, which will be 1 if there are more children
|
|
available outside the varobj's update range.
|
|
|
|
@item dynamic
|
|
This attribute will be present and have the value @samp{1} if the
|
|
varobj is a dynamic varobj. If the varobj is not a dynamic varobj,
|
|
then this attribute will not be present.
|
|
|
|
@item new_children
|
|
If new children were added to a dynamic varobj within the selected
|
|
update range (as set by @code{-var-set-update-range}), then they will
|
|
be listed in this attribute.
|
|
@end table
|
|
|
|
@subsubheading Example
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-var-assign var1 3
|
|
^done,value="3"
|
|
(gdb)
|
|
-var-update --all-values var1
|
|
^done,changelist=[@{name="var1",value="3",in_scope="true",
|
|
type_changed="false"@}]
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
@subheading The @code{-var-set-frozen} Command
|
|
@findex -var-set-frozen
|
|
@anchor{-var-set-frozen}
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-var-set-frozen @var{name} @var{flag}
|
|
@end smallexample
|
|
|
|
Set the frozenness flag on the variable object @var{name}. The
|
|
@var{flag} parameter should be either @samp{1} to make the variable
|
|
frozen or @samp{0} to make it unfrozen. If a variable object is
|
|
frozen, then neither itself, nor any of its children, are
|
|
implicitly updated by @code{-var-update} of
|
|
a parent variable or by @code{-var-update *}. Only
|
|
@code{-var-update} of the variable itself will update its value and
|
|
values of its children. After a variable object is unfrozen, it is
|
|
implicitly updated by all subsequent @code{-var-update} operations.
|
|
Unfreezing a variable does not update it, only subsequent
|
|
@code{-var-update} does.
|
|
|
|
@subsubheading Example
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-var-set-frozen V 1
|
|
^done
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
@subheading The @code{-var-set-update-range} command
|
|
@findex -var-set-update-range
|
|
@anchor{-var-set-update-range}
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-var-set-update-range @var{name} @var{from} @var{to}
|
|
@end smallexample
|
|
|
|
Set the range of children to be returned by future invocations of
|
|
@code{-var-update}.
|
|
|
|
@var{from} and @var{to} indicate the range of children to report. If
|
|
@var{from} or @var{to} is less than zero, the range is reset and all
|
|
children will be reported. Otherwise, children starting at @var{from}
|
|
(zero-based) and up to and excluding @var{to} will be reported.
|
|
|
|
@subsubheading Example
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-var-set-update-range V 1 2
|
|
^done
|
|
@end smallexample
|
|
|
|
@subheading The @code{-var-set-visualizer} command
|
|
@findex -var-set-visualizer
|
|
@anchor{-var-set-visualizer}
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-var-set-visualizer @var{name} @var{visualizer}
|
|
@end smallexample
|
|
|
|
Set a visualizer for the variable object @var{name}.
|
|
|
|
@var{visualizer} is the visualizer to use. The special value
|
|
@samp{None} means to disable any visualizer in use.
|
|
|
|
If not @samp{None}, @var{visualizer} must be a Python expression.
|
|
This expression must evaluate to a callable object which accepts a
|
|
single argument. @value{GDBN} will call this object with the value of
|
|
the varobj @var{name} as an argument (this is done so that the same
|
|
Python pretty-printing code can be used for both the CLI and MI).
|
|
When called, this object must return an object which conforms to the
|
|
pretty-printing interface (@pxref{Pretty Printing API}).
|
|
|
|
The pre-defined function @code{gdb.default_visualizer} may be used to
|
|
select a visualizer by following the built-in process
|
|
(@pxref{Selecting Pretty-Printers}). This is done automatically when
|
|
a varobj is created, and so ordinarily is not needed.
|
|
|
|
This feature is only available if Python support is enabled. The MI
|
|
command @code{-list-features} (@pxref{GDB/MI Miscellaneous Commands})
|
|
can be used to check this.
|
|
|
|
@subsubheading Example
|
|
|
|
Resetting the visualizer:
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-var-set-visualizer V None
|
|
^done
|
|
@end smallexample
|
|
|
|
Reselecting the default (type-based) visualizer:
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-var-set-visualizer V gdb.default_visualizer
|
|
^done
|
|
@end smallexample
|
|
|
|
Suppose @code{SomeClass} is a visualizer class. A lambda expression
|
|
can be used to instantiate this class for a varobj:
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-var-set-visualizer V "lambda val: SomeClass()"
|
|
^done
|
|
@end smallexample
|
|
|
|
@c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
@node GDB/MI Data Manipulation
|
|
@section @sc{gdb/mi} Data Manipulation
|
|
|
|
@cindex data manipulation, in @sc{gdb/mi}
|
|
@cindex @sc{gdb/mi}, data manipulation
|
|
This section describes the @sc{gdb/mi} commands that manipulate data:
|
|
examine memory and registers, evaluate expressions, etc.
|
|
|
|
@c REMOVED FROM THE INTERFACE.
|
|
@c @subheading -data-assign
|
|
@c Change the value of a program variable. Plenty of side effects.
|
|
@c @subsubheading GDB Command
|
|
@c set variable
|
|
@c @subsubheading Example
|
|
@c N.A.
|
|
|
|
@subheading The @code{-data-disassemble} Command
|
|
@findex -data-disassemble
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-data-disassemble
|
|
[ -s @var{start-addr} -e @var{end-addr} ]
|
|
| [ -f @var{filename} -l @var{linenum} [ -n @var{lines} ] ]
|
|
-- @var{mode}
|
|
@end smallexample
|
|
|
|
@noindent
|
|
Where:
|
|
|
|
@table @samp
|
|
@item @var{start-addr}
|
|
is the beginning address (or @code{$pc})
|
|
@item @var{end-addr}
|
|
is the end address
|
|
@item @var{filename}
|
|
is the name of the file to disassemble
|
|
@item @var{linenum}
|
|
is the line number to disassemble around
|
|
@item @var{lines}
|
|
is the number of disassembly lines to be produced. If it is -1,
|
|
the whole function will be disassembled, in case no @var{end-addr} is
|
|
specified. If @var{end-addr} is specified as a non-zero value, and
|
|
@var{lines} is lower than the number of disassembly lines between
|
|
@var{start-addr} and @var{end-addr}, only @var{lines} lines are
|
|
displayed; if @var{lines} is higher than the number of lines between
|
|
@var{start-addr} and @var{end-addr}, only the lines up to @var{end-addr}
|
|
are displayed.
|
|
@item @var{mode}
|
|
is either 0 (meaning only disassembly), 1 (meaning mixed source and
|
|
disassembly), 2 (meaning disassembly with raw opcodes), or 3 (meaning
|
|
mixed source and disassembly with raw opcodes).
|
|
@end table
|
|
|
|
@subsubheading Result
|
|
|
|
The output for each instruction is composed of four fields:
|
|
|
|
@itemize @bullet
|
|
@item Address
|
|
@item Func-name
|
|
@item Offset
|
|
@item Instruction
|
|
@end itemize
|
|
|
|
Note that whatever included in the instruction field, is not manipulated
|
|
directly by @sc{gdb/mi}, i.e., it is not possible to adjust its format.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
There's no direct mapping from this command to the CLI.
|
|
|
|
@subsubheading Example
|
|
|
|
Disassemble from the current value of @code{$pc} to @code{$pc + 20}:
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-data-disassemble -s $pc -e "$pc + 20" -- 0
|
|
^done,
|
|
asm_insns=[
|
|
@{address="0x000107c0",func-name="main",offset="4",
|
|
inst="mov 2, %o0"@},
|
|
@{address="0x000107c4",func-name="main",offset="8",
|
|
inst="sethi %hi(0x11800), %o2"@},
|
|
@{address="0x000107c8",func-name="main",offset="12",
|
|
inst="or %o2, 0x140, %o1\t! 0x11940 <_lib_version+8>"@},
|
|
@{address="0x000107cc",func-name="main",offset="16",
|
|
inst="sethi %hi(0x11800), %o2"@},
|
|
@{address="0x000107d0",func-name="main",offset="20",
|
|
inst="or %o2, 0x168, %o4\t! 0x11968 <_lib_version+48>"@}]
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
Disassemble the whole @code{main} function. Line 32 is part of
|
|
@code{main}.
|
|
|
|
@smallexample
|
|
-data-disassemble -f basics.c -l 32 -- 0
|
|
^done,asm_insns=[
|
|
@{address="0x000107bc",func-name="main",offset="0",
|
|
inst="save %sp, -112, %sp"@},
|
|
@{address="0x000107c0",func-name="main",offset="4",
|
|
inst="mov 2, %o0"@},
|
|
@{address="0x000107c4",func-name="main",offset="8",
|
|
inst="sethi %hi(0x11800), %o2"@},
|
|
[@dots{}]
|
|
@{address="0x0001081c",func-name="main",offset="96",inst="ret "@},
|
|
@{address="0x00010820",func-name="main",offset="100",inst="restore "@}]
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
Disassemble 3 instructions from the start of @code{main}:
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-data-disassemble -f basics.c -l 32 -n 3 -- 0
|
|
^done,asm_insns=[
|
|
@{address="0x000107bc",func-name="main",offset="0",
|
|
inst="save %sp, -112, %sp"@},
|
|
@{address="0x000107c0",func-name="main",offset="4",
|
|
inst="mov 2, %o0"@},
|
|
@{address="0x000107c4",func-name="main",offset="8",
|
|
inst="sethi %hi(0x11800), %o2"@}]
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
Disassemble 3 instructions from the start of @code{main} in mixed mode:
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-data-disassemble -f basics.c -l 32 -n 3 -- 1
|
|
^done,asm_insns=[
|
|
src_and_asm_line=@{line="31",
|
|
file="/kwikemart/marge/ezannoni/flathead-dev/devo/gdb/ \
|
|
testsuite/gdb.mi/basics.c",line_asm_insn=[
|
|
@{address="0x000107bc",func-name="main",offset="0",
|
|
inst="save %sp, -112, %sp"@}]@},
|
|
src_and_asm_line=@{line="32",
|
|
file="/kwikemart/marge/ezannoni/flathead-dev/devo/gdb/ \
|
|
testsuite/gdb.mi/basics.c",line_asm_insn=[
|
|
@{address="0x000107c0",func-name="main",offset="4",
|
|
inst="mov 2, %o0"@},
|
|
@{address="0x000107c4",func-name="main",offset="8",
|
|
inst="sethi %hi(0x11800), %o2"@}]@}]
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
|
|
@subheading The @code{-data-evaluate-expression} Command
|
|
@findex -data-evaluate-expression
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-data-evaluate-expression @var{expr}
|
|
@end smallexample
|
|
|
|
Evaluate @var{expr} as an expression. The expression could contain an
|
|
inferior function call. The function call will execute synchronously.
|
|
If the expression contains spaces, it must be enclosed in double quotes.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} commands are @samp{print}, @samp{output}, and
|
|
@samp{call}. In @code{gdbtk} only, there's a corresponding
|
|
@samp{gdb_eval} command.
|
|
|
|
@subsubheading Example
|
|
|
|
In the following example, the numbers that precede the commands are the
|
|
@dfn{tokens} described in @ref{GDB/MI Command Syntax, ,@sc{gdb/mi}
|
|
Command Syntax}. Notice how @sc{gdb/mi} returns the same tokens in its
|
|
output.
|
|
|
|
@smallexample
|
|
211-data-evaluate-expression A
|
|
211^done,value="1"
|
|
(gdb)
|
|
311-data-evaluate-expression &A
|
|
311^done,value="0xefffeb7c"
|
|
(gdb)
|
|
411-data-evaluate-expression A+3
|
|
411^done,value="4"
|
|
(gdb)
|
|
511-data-evaluate-expression "A + 3"
|
|
511^done,value="4"
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
|
|
@subheading The @code{-data-list-changed-registers} Command
|
|
@findex -data-list-changed-registers
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-data-list-changed-registers
|
|
@end smallexample
|
|
|
|
Display a list of the registers that have changed.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
@value{GDBN} doesn't have a direct analog for this command; @code{gdbtk}
|
|
has the corresponding command @samp{gdb_changed_register_list}.
|
|
|
|
@subsubheading Example
|
|
|
|
On a PPC MBX board:
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-exec-continue
|
|
^running
|
|
|
|
(gdb)
|
|
*stopped,reason="breakpoint-hit",disp="keep",bkptno="1",frame=@{
|
|
func="main",args=[],file="try.c",fullname="/home/foo/bar/try.c",
|
|
line="5"@}
|
|
(gdb)
|
|
-data-list-changed-registers
|
|
^done,changed-registers=["0","1","2","4","5","6","7","8","9",
|
|
"10","11","13","14","15","16","17","18","19","20","21","22","23",
|
|
"24","25","26","27","28","30","31","64","65","66","67","69"]
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
|
|
@subheading The @code{-data-list-register-names} Command
|
|
@findex -data-list-register-names
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-data-list-register-names [ ( @var{regno} )+ ]
|
|
@end smallexample
|
|
|
|
Show a list of register names for the current target. If no arguments
|
|
are given, it shows a list of the names of all the registers. If
|
|
integer numbers are given as arguments, it will print a list of the
|
|
names of the registers corresponding to the arguments. To ensure
|
|
consistency between a register name and its number, the output list may
|
|
include empty register names.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
@value{GDBN} does not have a command which corresponds to
|
|
@samp{-data-list-register-names}. In @code{gdbtk} there is a
|
|
corresponding command @samp{gdb_regnames}.
|
|
|
|
@subsubheading Example
|
|
|
|
For the PPC MBX board:
|
|
@smallexample
|
|
(gdb)
|
|
-data-list-register-names
|
|
^done,register-names=["r0","r1","r2","r3","r4","r5","r6","r7",
|
|
"r8","r9","r10","r11","r12","r13","r14","r15","r16","r17","r18",
|
|
"r19","r20","r21","r22","r23","r24","r25","r26","r27","r28","r29",
|
|
"r30","r31","f0","f1","f2","f3","f4","f5","f6","f7","f8","f9",
|
|
"f10","f11","f12","f13","f14","f15","f16","f17","f18","f19","f20",
|
|
"f21","f22","f23","f24","f25","f26","f27","f28","f29","f30","f31",
|
|
"", "pc","ps","cr","lr","ctr","xer"]
|
|
(gdb)
|
|
-data-list-register-names 1 2 3
|
|
^done,register-names=["r1","r2","r3"]
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
@subheading The @code{-data-list-register-values} Command
|
|
@findex -data-list-register-values
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-data-list-register-values @var{fmt} [ ( @var{regno} )*]
|
|
@end smallexample
|
|
|
|
Display the registers' contents. @var{fmt} is the format according to
|
|
which the registers' contents are to be returned, followed by an optional
|
|
list of numbers specifying the registers to display. A missing list of
|
|
numbers indicates that the contents of all the registers must be returned.
|
|
|
|
Allowed formats for @var{fmt} are:
|
|
|
|
@table @code
|
|
@item x
|
|
Hexadecimal
|
|
@item o
|
|
Octal
|
|
@item t
|
|
Binary
|
|
@item d
|
|
Decimal
|
|
@item r
|
|
Raw
|
|
@item N
|
|
Natural
|
|
@end table
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} commands are @samp{info reg}, @samp{info
|
|
all-reg}, and (in @code{gdbtk}) @samp{gdb_fetch_registers}.
|
|
|
|
@subsubheading Example
|
|
|
|
For a PPC MBX board (note: line breaks are for readability only, they
|
|
don't appear in the actual output):
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-data-list-register-values r 64 65
|
|
^done,register-values=[@{number="64",value="0xfe00a300"@},
|
|
@{number="65",value="0x00029002"@}]
|
|
(gdb)
|
|
-data-list-register-values x
|
|
^done,register-values=[@{number="0",value="0xfe0043c8"@},
|
|
@{number="1",value="0x3fff88"@},@{number="2",value="0xfffffffe"@},
|
|
@{number="3",value="0x0"@},@{number="4",value="0xa"@},
|
|
@{number="5",value="0x3fff68"@},@{number="6",value="0x3fff58"@},
|
|
@{number="7",value="0xfe011e98"@},@{number="8",value="0x2"@},
|
|
@{number="9",value="0xfa202820"@},@{number="10",value="0xfa202808"@},
|
|
@{number="11",value="0x1"@},@{number="12",value="0x0"@},
|
|
@{number="13",value="0x4544"@},@{number="14",value="0xffdfffff"@},
|
|
@{number="15",value="0xffffffff"@},@{number="16",value="0xfffffeff"@},
|
|
@{number="17",value="0xefffffed"@},@{number="18",value="0xfffffffe"@},
|
|
@{number="19",value="0xffffffff"@},@{number="20",value="0xffffffff"@},
|
|
@{number="21",value="0xffffffff"@},@{number="22",value="0xfffffff7"@},
|
|
@{number="23",value="0xffffffff"@},@{number="24",value="0xffffffff"@},
|
|
@{number="25",value="0xffffffff"@},@{number="26",value="0xfffffffb"@},
|
|
@{number="27",value="0xffffffff"@},@{number="28",value="0xf7bfffff"@},
|
|
@{number="29",value="0x0"@},@{number="30",value="0xfe010000"@},
|
|
@{number="31",value="0x0"@},@{number="32",value="0x0"@},
|
|
@{number="33",value="0x0"@},@{number="34",value="0x0"@},
|
|
@{number="35",value="0x0"@},@{number="36",value="0x0"@},
|
|
@{number="37",value="0x0"@},@{number="38",value="0x0"@},
|
|
@{number="39",value="0x0"@},@{number="40",value="0x0"@},
|
|
@{number="41",value="0x0"@},@{number="42",value="0x0"@},
|
|
@{number="43",value="0x0"@},@{number="44",value="0x0"@},
|
|
@{number="45",value="0x0"@},@{number="46",value="0x0"@},
|
|
@{number="47",value="0x0"@},@{number="48",value="0x0"@},
|
|
@{number="49",value="0x0"@},@{number="50",value="0x0"@},
|
|
@{number="51",value="0x0"@},@{number="52",value="0x0"@},
|
|
@{number="53",value="0x0"@},@{number="54",value="0x0"@},
|
|
@{number="55",value="0x0"@},@{number="56",value="0x0"@},
|
|
@{number="57",value="0x0"@},@{number="58",value="0x0"@},
|
|
@{number="59",value="0x0"@},@{number="60",value="0x0"@},
|
|
@{number="61",value="0x0"@},@{number="62",value="0x0"@},
|
|
@{number="63",value="0x0"@},@{number="64",value="0xfe00a300"@},
|
|
@{number="65",value="0x29002"@},@{number="66",value="0x202f04b5"@},
|
|
@{number="67",value="0xfe0043b0"@},@{number="68",value="0xfe00b3e4"@},
|
|
@{number="69",value="0x20002b03"@}]
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
|
|
@subheading The @code{-data-read-memory} Command
|
|
@findex -data-read-memory
|
|
|
|
This command is deprecated, use @code{-data-read-memory-bytes} instead.
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-data-read-memory [ -o @var{byte-offset} ]
|
|
@var{address} @var{word-format} @var{word-size}
|
|
@var{nr-rows} @var{nr-cols} [ @var{aschar} ]
|
|
@end smallexample
|
|
|
|
@noindent
|
|
where:
|
|
|
|
@table @samp
|
|
@item @var{address}
|
|
An expression specifying the address of the first memory word to be
|
|
read. Complex expressions containing embedded white space should be
|
|
quoted using the C convention.
|
|
|
|
@item @var{word-format}
|
|
The format to be used to print the memory words. The notation is the
|
|
same as for @value{GDBN}'s @code{print} command (@pxref{Output Formats,
|
|
,Output Formats}).
|
|
|
|
@item @var{word-size}
|
|
The size of each memory word in bytes.
|
|
|
|
@item @var{nr-rows}
|
|
The number of rows in the output table.
|
|
|
|
@item @var{nr-cols}
|
|
The number of columns in the output table.
|
|
|
|
@item @var{aschar}
|
|
If present, indicates that each row should include an @sc{ascii} dump. The
|
|
value of @var{aschar} is used as a padding character when a byte is not a
|
|
member of the printable @sc{ascii} character set (printable @sc{ascii}
|
|
characters are those whose code is between 32 and 126, inclusively).
|
|
|
|
@item @var{byte-offset}
|
|
An offset to add to the @var{address} before fetching memory.
|
|
@end table
|
|
|
|
This command displays memory contents as a table of @var{nr-rows} by
|
|
@var{nr-cols} words, each word being @var{word-size} bytes. In total,
|
|
@code{@var{nr-rows} * @var{nr-cols} * @var{word-size}} bytes are read
|
|
(returned as @samp{total-bytes}). Should less than the requested number
|
|
of bytes be returned by the target, the missing words are identified
|
|
using @samp{N/A}. The number of bytes read from the target is returned
|
|
in @samp{nr-bytes} and the starting address used to read memory in
|
|
@samp{addr}.
|
|
|
|
The address of the next/previous row or page is available in
|
|
@samp{next-row} and @samp{prev-row}, @samp{next-page} and
|
|
@samp{prev-page}.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} command is @samp{x}. @code{gdbtk} has
|
|
@samp{gdb_get_mem} memory read command.
|
|
|
|
@subsubheading Example
|
|
|
|
Read six bytes of memory starting at @code{bytes+6} but then offset by
|
|
@code{-6} bytes. Format as three rows of two columns. One byte per
|
|
word. Display each word in hex.
|
|
|
|
@smallexample
|
|
(gdb)
|
|
9-data-read-memory -o -6 -- bytes+6 x 1 3 2
|
|
9^done,addr="0x00001390",nr-bytes="6",total-bytes="6",
|
|
next-row="0x00001396",prev-row="0x0000138e",next-page="0x00001396",
|
|
prev-page="0x0000138a",memory=[
|
|
@{addr="0x00001390",data=["0x00","0x01"]@},
|
|
@{addr="0x00001392",data=["0x02","0x03"]@},
|
|
@{addr="0x00001394",data=["0x04","0x05"]@}]
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
Read two bytes of memory starting at address @code{shorts + 64} and
|
|
display as a single word formatted in decimal.
|
|
|
|
@smallexample
|
|
(gdb)
|
|
5-data-read-memory shorts+64 d 2 1 1
|
|
5^done,addr="0x00001510",nr-bytes="2",total-bytes="2",
|
|
next-row="0x00001512",prev-row="0x0000150e",
|
|
next-page="0x00001512",prev-page="0x0000150e",memory=[
|
|
@{addr="0x00001510",data=["128"]@}]
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
Read thirty two bytes of memory starting at @code{bytes+16} and format
|
|
as eight rows of four columns. Include a string encoding with @samp{x}
|
|
used as the non-printable character.
|
|
|
|
@smallexample
|
|
(gdb)
|
|
4-data-read-memory bytes+16 x 1 8 4 x
|
|
4^done,addr="0x000013a0",nr-bytes="32",total-bytes="32",
|
|
next-row="0x000013c0",prev-row="0x0000139c",
|
|
next-page="0x000013c0",prev-page="0x00001380",memory=[
|
|
@{addr="0x000013a0",data=["0x10","0x11","0x12","0x13"],ascii="xxxx"@},
|
|
@{addr="0x000013a4",data=["0x14","0x15","0x16","0x17"],ascii="xxxx"@},
|
|
@{addr="0x000013a8",data=["0x18","0x19","0x1a","0x1b"],ascii="xxxx"@},
|
|
@{addr="0x000013ac",data=["0x1c","0x1d","0x1e","0x1f"],ascii="xxxx"@},
|
|
@{addr="0x000013b0",data=["0x20","0x21","0x22","0x23"],ascii=" !\"#"@},
|
|
@{addr="0x000013b4",data=["0x24","0x25","0x26","0x27"],ascii="$%&'"@},
|
|
@{addr="0x000013b8",data=["0x28","0x29","0x2a","0x2b"],ascii="()*+"@},
|
|
@{addr="0x000013bc",data=["0x2c","0x2d","0x2e","0x2f"],ascii=",-./"@}]
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
@subheading The @code{-data-read-memory-bytes} Command
|
|
@findex -data-read-memory-bytes
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-data-read-memory-bytes [ -o @var{byte-offset} ]
|
|
@var{address} @var{count}
|
|
@end smallexample
|
|
|
|
@noindent
|
|
where:
|
|
|
|
@table @samp
|
|
@item @var{address}
|
|
An expression specifying the address of the first memory word to be
|
|
read. Complex expressions containing embedded white space should be
|
|
quoted using the C convention.
|
|
|
|
@item @var{count}
|
|
The number of bytes to read. This should be an integer literal.
|
|
|
|
@item @var{byte-offset}
|
|
The offsets in bytes relative to @var{address} at which to start
|
|
reading. This should be an integer literal. This option is provided
|
|
so that a frontend is not required to first evaluate address and then
|
|
perform address arithmetics itself.
|
|
|
|
@end table
|
|
|
|
This command attempts to read all accessible memory regions in the
|
|
specified range. First, all regions marked as unreadable in the memory
|
|
map (if one is defined) will be skipped. @xref{Memory Region
|
|
Attributes}. Second, @value{GDBN} will attempt to read the remaining
|
|
regions. For each one, if reading full region results in an errors,
|
|
@value{GDBN} will try to read a subset of the region.
|
|
|
|
In general, every single byte in the region may be readable or not,
|
|
and the only way to read every readable byte is to try a read at
|
|
every address, which is not practical. Therefore, @value{GDBN} will
|
|
attempt to read all accessible bytes at either beginning or the end
|
|
of the region, using a binary division scheme. This heuristic works
|
|
well for reading accross a memory map boundary. Note that if a region
|
|
has a readable range that is neither at the beginning or the end,
|
|
@value{GDBN} will not read it.
|
|
|
|
The result record (@pxref{GDB/MI Result Records}) that is output of
|
|
the command includes a field named @samp{memory} whose content is a
|
|
list of tuples. Each tuple represent a successfully read memory block
|
|
and has the following fields:
|
|
|
|
@table @code
|
|
@item begin
|
|
The start address of the memory block, as hexadecimal literal.
|
|
|
|
@item end
|
|
The end address of the memory block, as hexadecimal literal.
|
|
|
|
@item offset
|
|
The offset of the memory block, as hexadecimal literal, relative to
|
|
the start address passed to @code{-data-read-memory-bytes}.
|
|
|
|
@item contents
|
|
The contents of the memory block, in hex.
|
|
|
|
@end table
|
|
|
|
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} command is @samp{x}.
|
|
|
|
@subsubheading Example
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-data-read-memory-bytes &a 10
|
|
^done,memory=[@{begin="0xbffff154",offset="0x00000000",
|
|
end="0xbffff15e",
|
|
contents="01000000020000000300"@}]
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
|
|
@subheading The @code{-data-write-memory-bytes} Command
|
|
@findex -data-write-memory-bytes
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-data-write-memory-bytes @var{address} @var{contents}
|
|
@end smallexample
|
|
|
|
@noindent
|
|
where:
|
|
|
|
@table @samp
|
|
@item @var{address}
|
|
An expression specifying the address of the first memory word to be
|
|
read. Complex expressions containing embedded white space should be
|
|
quoted using the C convention.
|
|
|
|
@item @var{contents}
|
|
The hex-encoded bytes to write.
|
|
|
|
@end table
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
There's no corresponding @value{GDBN} command.
|
|
|
|
@subsubheading Example
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-data-write-memory-bytes &a "aabbccdd"
|
|
^done
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
|
|
@c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
@node GDB/MI Tracepoint Commands
|
|
@section @sc{gdb/mi} Tracepoint Commands
|
|
|
|
The commands defined in this section implement MI support for
|
|
tracepoints. For detailed introduction, see @ref{Tracepoints}.
|
|
|
|
@subheading The @code{-trace-find} Command
|
|
@findex -trace-find
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-trace-find @var{mode} [@var{parameters}@dots{}]
|
|
@end smallexample
|
|
|
|
Find a trace frame using criteria defined by @var{mode} and
|
|
@var{parameters}. The following table lists permissible
|
|
modes and their parameters. For details of operation, see @ref{tfind}.
|
|
|
|
@table @samp
|
|
|
|
@item none
|
|
No parameters are required. Stops examining trace frames.
|
|
|
|
@item frame-number
|
|
An integer is required as parameter. Selects tracepoint frame with
|
|
that index.
|
|
|
|
@item tracepoint-number
|
|
An integer is required as parameter. Finds next
|
|
trace frame that corresponds to tracepoint with the specified number.
|
|
|
|
@item pc
|
|
An address is required as parameter. Finds
|
|
next trace frame that corresponds to any tracepoint at the specified
|
|
address.
|
|
|
|
@item pc-inside-range
|
|
Two addresses are required as parameters. Finds next trace
|
|
frame that corresponds to a tracepoint at an address inside the
|
|
specified range. Both bounds are considered to be inside the range.
|
|
|
|
@item pc-outside-range
|
|
Two addresses are required as parameters. Finds
|
|
next trace frame that corresponds to a tracepoint at an address outside
|
|
the specified range. Both bounds are considered to be inside the range.
|
|
|
|
@item line
|
|
Line specification is required as parameter. @xref{Specify Location}.
|
|
Finds next trace frame that corresponds to a tracepoint at
|
|
the specified location.
|
|
|
|
@end table
|
|
|
|
If @samp{none} was passed as @var{mode}, the response does not
|
|
have fields. Otherwise, the response may have the following fields:
|
|
|
|
@table @samp
|
|
@item found
|
|
This field has either @samp{0} or @samp{1} as the value, depending
|
|
on whether a matching tracepoint was found.
|
|
|
|
@item traceframe
|
|
The index of the found traceframe. This field is present iff
|
|
the @samp{found} field has value of @samp{1}.
|
|
|
|
@item tracepoint
|
|
The index of the found tracepoint. This field is present iff
|
|
the @samp{found} field has value of @samp{1}.
|
|
|
|
@item frame
|
|
The information about the frame corresponding to the found trace
|
|
frame. This field is present only if a trace frame was found.
|
|
@xref{GDB/MI Frame Information}, for description of this field.
|
|
|
|
@end table
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} command is @samp{tfind}.
|
|
|
|
@subheading -trace-define-variable
|
|
@findex -trace-define-variable
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-trace-define-variable @var{name} [ @var{value} ]
|
|
@end smallexample
|
|
|
|
Create trace variable @var{name} if it does not exist. If
|
|
@var{value} is specified, sets the initial value of the specified
|
|
trace variable to that value. Note that the @var{name} should start
|
|
with the @samp{$} character.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} command is @samp{tvariable}.
|
|
|
|
@subheading -trace-list-variables
|
|
@findex -trace-list-variables
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-trace-list-variables
|
|
@end smallexample
|
|
|
|
Return a table of all defined trace variables. Each element of the
|
|
table has the following fields:
|
|
|
|
@table @samp
|
|
@item name
|
|
The name of the trace variable. This field is always present.
|
|
|
|
@item initial
|
|
The initial value. This is a 64-bit signed integer. This
|
|
field is always present.
|
|
|
|
@item current
|
|
The value the trace variable has at the moment. This is a 64-bit
|
|
signed integer. This field is absent iff current value is
|
|
not defined, for example if the trace was never run, or is
|
|
presently running.
|
|
|
|
@end table
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} command is @samp{tvariables}.
|
|
|
|
@subsubheading Example
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-trace-list-variables
|
|
^done,trace-variables=@{nr_rows="1",nr_cols="3",
|
|
hdr=[@{width="15",alignment="-1",col_name="name",colhdr="Name"@},
|
|
@{width="11",alignment="-1",col_name="initial",colhdr="Initial"@},
|
|
@{width="11",alignment="-1",col_name="current",colhdr="Current"@}],
|
|
body=[variable=@{name="$trace_timestamp",initial="0"@}
|
|
variable=@{name="$foo",initial="10",current="15"@}]@}
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
@subheading -trace-save
|
|
@findex -trace-save
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-trace-save [-r ] @var{filename}
|
|
@end smallexample
|
|
|
|
Saves the collected trace data to @var{filename}. Without the
|
|
@samp{-r} option, the data is downloaded from the target and saved
|
|
in a local file. With the @samp{-r} option the target is asked
|
|
to perform the save.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} command is @samp{tsave}.
|
|
|
|
|
|
@subheading -trace-start
|
|
@findex -trace-start
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-trace-start
|
|
@end smallexample
|
|
|
|
Starts a tracing experiments. The result of this command does not
|
|
have any fields.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} command is @samp{tstart}.
|
|
|
|
@subheading -trace-status
|
|
@findex -trace-status
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-trace-status
|
|
@end smallexample
|
|
|
|
Obtains the status of a tracing experiment. The result may include
|
|
the following fields:
|
|
|
|
@table @samp
|
|
|
|
@item supported
|
|
May have a value of either @samp{0}, when no tracing operations are
|
|
supported, @samp{1}, when all tracing operations are supported, or
|
|
@samp{file} when examining trace file. In the latter case, examining
|
|
of trace frame is possible but new tracing experiement cannot be
|
|
started. This field is always present.
|
|
|
|
@item running
|
|
May have a value of either @samp{0} or @samp{1} depending on whether
|
|
tracing experiement is in progress on target. This field is present
|
|
if @samp{supported} field is not @samp{0}.
|
|
|
|
@item stop-reason
|
|
Report the reason why the tracing was stopped last time. This field
|
|
may be absent iff tracing was never stopped on target yet. The
|
|
value of @samp{request} means the tracing was stopped as result of
|
|
the @code{-trace-stop} command. The value of @samp{overflow} means
|
|
the tracing buffer is full. The value of @samp{disconnection} means
|
|
tracing was automatically stopped when @value{GDBN} has disconnected.
|
|
The value of @samp{passcount} means tracing was stopped when a
|
|
tracepoint was passed a maximal number of times for that tracepoint.
|
|
This field is present if @samp{supported} field is not @samp{0}.
|
|
|
|
@item stopping-tracepoint
|
|
The number of tracepoint whose passcount as exceeded. This field is
|
|
present iff the @samp{stop-reason} field has the value of
|
|
@samp{passcount}.
|
|
|
|
@item frames
|
|
@itemx frames-created
|
|
The @samp{frames} field is a count of the total number of trace frames
|
|
in the trace buffer, while @samp{frames-created} is the total created
|
|
during the run, including ones that were discarded, such as when a
|
|
circular trace buffer filled up. Both fields are optional.
|
|
|
|
@item buffer-size
|
|
@itemx buffer-free
|
|
These fields tell the current size of the tracing buffer and the
|
|
remaining space. These fields are optional.
|
|
|
|
@item circular
|
|
The value of the circular trace buffer flag. @code{1} means that the
|
|
trace buffer is circular and old trace frames will be discarded if
|
|
necessary to make room, @code{0} means that the trace buffer is linear
|
|
and may fill up.
|
|
|
|
@item disconnected
|
|
The value of the disconnected tracing flag. @code{1} means that
|
|
tracing will continue after @value{GDBN} disconnects, @code{0} means
|
|
that the trace run will stop.
|
|
|
|
@end table
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} command is @samp{tstatus}.
|
|
|
|
@subheading -trace-stop
|
|
@findex -trace-stop
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-trace-stop
|
|
@end smallexample
|
|
|
|
Stops a tracing experiment. The result of this command has the same
|
|
fields as @code{-trace-status}, except that the @samp{supported} and
|
|
@samp{running} fields are not output.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} command is @samp{tstop}.
|
|
|
|
|
|
@c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
@node GDB/MI Symbol Query
|
|
@section @sc{gdb/mi} Symbol Query Commands
|
|
|
|
|
|
@ignore
|
|
@subheading The @code{-symbol-info-address} Command
|
|
@findex -symbol-info-address
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-symbol-info-address @var{symbol}
|
|
@end smallexample
|
|
|
|
Describe where @var{symbol} is stored.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} command is @samp{info address}.
|
|
|
|
@subsubheading Example
|
|
N.A.
|
|
|
|
|
|
@subheading The @code{-symbol-info-file} Command
|
|
@findex -symbol-info-file
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-symbol-info-file
|
|
@end smallexample
|
|
|
|
Show the file for the symbol.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
There's no equivalent @value{GDBN} command. @code{gdbtk} has
|
|
@samp{gdb_find_file}.
|
|
|
|
@subsubheading Example
|
|
N.A.
|
|
|
|
|
|
@subheading The @code{-symbol-info-function} Command
|
|
@findex -symbol-info-function
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-symbol-info-function
|
|
@end smallexample
|
|
|
|
Show which function the symbol lives in.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
@samp{gdb_get_function} in @code{gdbtk}.
|
|
|
|
@subsubheading Example
|
|
N.A.
|
|
|
|
|
|
@subheading The @code{-symbol-info-line} Command
|
|
@findex -symbol-info-line
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-symbol-info-line
|
|
@end smallexample
|
|
|
|
Show the core addresses of the code for a source line.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} command is @samp{info line}.
|
|
@code{gdbtk} has the @samp{gdb_get_line} and @samp{gdb_get_file} commands.
|
|
|
|
@subsubheading Example
|
|
N.A.
|
|
|
|
|
|
@subheading The @code{-symbol-info-symbol} Command
|
|
@findex -symbol-info-symbol
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-symbol-info-symbol @var{addr}
|
|
@end smallexample
|
|
|
|
Describe what symbol is at location @var{addr}.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} command is @samp{info symbol}.
|
|
|
|
@subsubheading Example
|
|
N.A.
|
|
|
|
|
|
@subheading The @code{-symbol-list-functions} Command
|
|
@findex -symbol-list-functions
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-symbol-list-functions
|
|
@end smallexample
|
|
|
|
List the functions in the executable.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
@samp{info functions} in @value{GDBN}, @samp{gdb_listfunc} and
|
|
@samp{gdb_search} in @code{gdbtk}.
|
|
|
|
@subsubheading Example
|
|
N.A.
|
|
@end ignore
|
|
|
|
|
|
@subheading The @code{-symbol-list-lines} Command
|
|
@findex -symbol-list-lines
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-symbol-list-lines @var{filename}
|
|
@end smallexample
|
|
|
|
Print the list of lines that contain code and their associated program
|
|
addresses for the given source filename. The entries are sorted in
|
|
ascending PC order.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
There is no corresponding @value{GDBN} command.
|
|
|
|
@subsubheading Example
|
|
@smallexample
|
|
(gdb)
|
|
-symbol-list-lines basics.c
|
|
^done,lines=[@{pc="0x08048554",line="7"@},@{pc="0x0804855a",line="8"@}]
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
|
|
@ignore
|
|
@subheading The @code{-symbol-list-types} Command
|
|
@findex -symbol-list-types
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-symbol-list-types
|
|
@end smallexample
|
|
|
|
List all the type names.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding commands are @samp{info types} in @value{GDBN},
|
|
@samp{gdb_search} in @code{gdbtk}.
|
|
|
|
@subsubheading Example
|
|
N.A.
|
|
|
|
|
|
@subheading The @code{-symbol-list-variables} Command
|
|
@findex -symbol-list-variables
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-symbol-list-variables
|
|
@end smallexample
|
|
|
|
List all the global and static variable names.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
@samp{info variables} in @value{GDBN}, @samp{gdb_search} in @code{gdbtk}.
|
|
|
|
@subsubheading Example
|
|
N.A.
|
|
|
|
|
|
@subheading The @code{-symbol-locate} Command
|
|
@findex -symbol-locate
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-symbol-locate
|
|
@end smallexample
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
@samp{gdb_loc} in @code{gdbtk}.
|
|
|
|
@subsubheading Example
|
|
N.A.
|
|
|
|
|
|
@subheading The @code{-symbol-type} Command
|
|
@findex -symbol-type
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-symbol-type @var{variable}
|
|
@end smallexample
|
|
|
|
Show type of @var{variable}.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} command is @samp{ptype}, @code{gdbtk} has
|
|
@samp{gdb_obj_variable}.
|
|
|
|
@subsubheading Example
|
|
N.A.
|
|
@end ignore
|
|
|
|
|
|
@c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
@node GDB/MI File Commands
|
|
@section @sc{gdb/mi} File Commands
|
|
|
|
This section describes the GDB/MI commands to specify executable file names
|
|
and to read in and obtain symbol table information.
|
|
|
|
@subheading The @code{-file-exec-and-symbols} Command
|
|
@findex -file-exec-and-symbols
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-file-exec-and-symbols @var{file}
|
|
@end smallexample
|
|
|
|
Specify the executable file to be debugged. This file is the one from
|
|
which the symbol table is also read. If no file is specified, the
|
|
command clears the executable and symbol information. If breakpoints
|
|
are set when using this command with no arguments, @value{GDBN} will produce
|
|
error messages. Otherwise, no output is produced, except a completion
|
|
notification.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} command is @samp{file}.
|
|
|
|
@subsubheading Example
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-file-exec-and-symbols /kwikemart/marge/ezannoni/TRUNK/mbx/hello.mbx
|
|
^done
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
|
|
@subheading The @code{-file-exec-file} Command
|
|
@findex -file-exec-file
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-file-exec-file @var{file}
|
|
@end smallexample
|
|
|
|
Specify the executable file to be debugged. Unlike
|
|
@samp{-file-exec-and-symbols}, the symbol table is @emph{not} read
|
|
from this file. If used without argument, @value{GDBN} clears the information
|
|
about the executable file. No output is produced, except a completion
|
|
notification.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} command is @samp{exec-file}.
|
|
|
|
@subsubheading Example
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-file-exec-file /kwikemart/marge/ezannoni/TRUNK/mbx/hello.mbx
|
|
^done
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
|
|
@ignore
|
|
@subheading The @code{-file-list-exec-sections} Command
|
|
@findex -file-list-exec-sections
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-file-list-exec-sections
|
|
@end smallexample
|
|
|
|
List the sections of the current executable file.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The @value{GDBN} command @samp{info file} shows, among the rest, the same
|
|
information as this command. @code{gdbtk} has a corresponding command
|
|
@samp{gdb_load_info}.
|
|
|
|
@subsubheading Example
|
|
N.A.
|
|
@end ignore
|
|
|
|
|
|
@subheading The @code{-file-list-exec-source-file} Command
|
|
@findex -file-list-exec-source-file
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-file-list-exec-source-file
|
|
@end smallexample
|
|
|
|
List the line number, the current source file, and the absolute path
|
|
to the current source file for the current executable. The macro
|
|
information field has a value of @samp{1} or @samp{0} depending on
|
|
whether or not the file includes preprocessor macro information.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The @value{GDBN} equivalent is @samp{info source}
|
|
|
|
@subsubheading Example
|
|
|
|
@smallexample
|
|
(gdb)
|
|
123-file-list-exec-source-file
|
|
123^done,line="1",file="foo.c",fullname="/home/bar/foo.c,macro-info="1"
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
|
|
@subheading The @code{-file-list-exec-source-files} Command
|
|
@findex -file-list-exec-source-files
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-file-list-exec-source-files
|
|
@end smallexample
|
|
|
|
List the source files for the current executable.
|
|
|
|
It will always output the filename, but only when @value{GDBN} can find
|
|
the absolute file name of a source file, will it output the fullname.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The @value{GDBN} equivalent is @samp{info sources}.
|
|
@code{gdbtk} has an analogous command @samp{gdb_listfiles}.
|
|
|
|
@subsubheading Example
|
|
@smallexample
|
|
(gdb)
|
|
-file-list-exec-source-files
|
|
^done,files=[
|
|
@{file=foo.c,fullname=/home/foo.c@},
|
|
@{file=/home/bar.c,fullname=/home/bar.c@},
|
|
@{file=gdb_could_not_find_fullpath.c@}]
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
@ignore
|
|
@subheading The @code{-file-list-shared-libraries} Command
|
|
@findex -file-list-shared-libraries
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-file-list-shared-libraries
|
|
@end smallexample
|
|
|
|
List the shared libraries in the program.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} command is @samp{info shared}.
|
|
|
|
@subsubheading Example
|
|
N.A.
|
|
|
|
|
|
@subheading The @code{-file-list-symbol-files} Command
|
|
@findex -file-list-symbol-files
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-file-list-symbol-files
|
|
@end smallexample
|
|
|
|
List symbol files.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} command is @samp{info file} (part of it).
|
|
|
|
@subsubheading Example
|
|
N.A.
|
|
@end ignore
|
|
|
|
|
|
@subheading The @code{-file-symbol-file} Command
|
|
@findex -file-symbol-file
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-file-symbol-file @var{file}
|
|
@end smallexample
|
|
|
|
Read symbol table info from the specified @var{file} argument. When
|
|
used without arguments, clears @value{GDBN}'s symbol table info. No output is
|
|
produced, except for a completion notification.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} command is @samp{symbol-file}.
|
|
|
|
@subsubheading Example
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-file-symbol-file /kwikemart/marge/ezannoni/TRUNK/mbx/hello.mbx
|
|
^done
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
@ignore
|
|
@c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
@node GDB/MI Memory Overlay Commands
|
|
@section @sc{gdb/mi} Memory Overlay Commands
|
|
|
|
The memory overlay commands are not implemented.
|
|
|
|
@c @subheading -overlay-auto
|
|
|
|
@c @subheading -overlay-list-mapping-state
|
|
|
|
@c @subheading -overlay-list-overlays
|
|
|
|
@c @subheading -overlay-map
|
|
|
|
@c @subheading -overlay-off
|
|
|
|
@c @subheading -overlay-on
|
|
|
|
@c @subheading -overlay-unmap
|
|
|
|
@c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
@node GDB/MI Signal Handling Commands
|
|
@section @sc{gdb/mi} Signal Handling Commands
|
|
|
|
Signal handling commands are not implemented.
|
|
|
|
@c @subheading -signal-handle
|
|
|
|
@c @subheading -signal-list-handle-actions
|
|
|
|
@c @subheading -signal-list-signal-types
|
|
@end ignore
|
|
|
|
|
|
@c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
@node GDB/MI Target Manipulation
|
|
@section @sc{gdb/mi} Target Manipulation Commands
|
|
|
|
|
|
@subheading The @code{-target-attach} Command
|
|
@findex -target-attach
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-target-attach @var{pid} | @var{gid} | @var{file}
|
|
@end smallexample
|
|
|
|
Attach to a process @var{pid} or a file @var{file} outside of
|
|
@value{GDBN}, or a thread group @var{gid}. If attaching to a thread
|
|
group, the id previously returned by
|
|
@samp{-list-thread-groups --available} must be used.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} command is @samp{attach}.
|
|
|
|
@subsubheading Example
|
|
@smallexample
|
|
(gdb)
|
|
-target-attach 34
|
|
=thread-created,id="1"
|
|
*stopped,thread-id="1",frame=@{addr="0xb7f7e410",func="bar",args=[]@}
|
|
^done
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
@ignore
|
|
@subheading The @code{-target-compare-sections} Command
|
|
@findex -target-compare-sections
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-target-compare-sections [ @var{section} ]
|
|
@end smallexample
|
|
|
|
Compare data of section @var{section} on target to the exec file.
|
|
Without the argument, all sections are compared.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The @value{GDBN} equivalent is @samp{compare-sections}.
|
|
|
|
@subsubheading Example
|
|
N.A.
|
|
@end ignore
|
|
|
|
|
|
@subheading The @code{-target-detach} Command
|
|
@findex -target-detach
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-target-detach [ @var{pid} | @var{gid} ]
|
|
@end smallexample
|
|
|
|
Detach from the remote target which normally resumes its execution.
|
|
If either @var{pid} or @var{gid} is specified, detaches from either
|
|
the specified process, or specified thread group. There's no output.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} command is @samp{detach}.
|
|
|
|
@subsubheading Example
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-target-detach
|
|
^done
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
|
|
@subheading The @code{-target-disconnect} Command
|
|
@findex -target-disconnect
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-target-disconnect
|
|
@end smallexample
|
|
|
|
Disconnect from the remote target. There's no output and the target is
|
|
generally not resumed.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} command is @samp{disconnect}.
|
|
|
|
@subsubheading Example
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-target-disconnect
|
|
^done
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
|
|
@subheading The @code{-target-download} Command
|
|
@findex -target-download
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-target-download
|
|
@end smallexample
|
|
|
|
Loads the executable onto the remote target.
|
|
It prints out an update message every half second, which includes the fields:
|
|
|
|
@table @samp
|
|
@item section
|
|
The name of the section.
|
|
@item section-sent
|
|
The size of what has been sent so far for that section.
|
|
@item section-size
|
|
The size of the section.
|
|
@item total-sent
|
|
The total size of what was sent so far (the current and the previous sections).
|
|
@item total-size
|
|
The size of the overall executable to download.
|
|
@end table
|
|
|
|
@noindent
|
|
Each message is sent as status record (@pxref{GDB/MI Output Syntax, ,
|
|
@sc{gdb/mi} Output Syntax}).
|
|
|
|
In addition, it prints the name and size of the sections, as they are
|
|
downloaded. These messages include the following fields:
|
|
|
|
@table @samp
|
|
@item section
|
|
The name of the section.
|
|
@item section-size
|
|
The size of the section.
|
|
@item total-size
|
|
The size of the overall executable to download.
|
|
@end table
|
|
|
|
@noindent
|
|
At the end, a summary is printed.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} command is @samp{load}.
|
|
|
|
@subsubheading Example
|
|
|
|
Note: each status message appears on a single line. Here the messages
|
|
have been broken down so that they can fit onto a page.
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-target-download
|
|
+download,@{section=".text",section-size="6668",total-size="9880"@}
|
|
+download,@{section=".text",section-sent="512",section-size="6668",
|
|
total-sent="512",total-size="9880"@}
|
|
+download,@{section=".text",section-sent="1024",section-size="6668",
|
|
total-sent="1024",total-size="9880"@}
|
|
+download,@{section=".text",section-sent="1536",section-size="6668",
|
|
total-sent="1536",total-size="9880"@}
|
|
+download,@{section=".text",section-sent="2048",section-size="6668",
|
|
total-sent="2048",total-size="9880"@}
|
|
+download,@{section=".text",section-sent="2560",section-size="6668",
|
|
total-sent="2560",total-size="9880"@}
|
|
+download,@{section=".text",section-sent="3072",section-size="6668",
|
|
total-sent="3072",total-size="9880"@}
|
|
+download,@{section=".text",section-sent="3584",section-size="6668",
|
|
total-sent="3584",total-size="9880"@}
|
|
+download,@{section=".text",section-sent="4096",section-size="6668",
|
|
total-sent="4096",total-size="9880"@}
|
|
+download,@{section=".text",section-sent="4608",section-size="6668",
|
|
total-sent="4608",total-size="9880"@}
|
|
+download,@{section=".text",section-sent="5120",section-size="6668",
|
|
total-sent="5120",total-size="9880"@}
|
|
+download,@{section=".text",section-sent="5632",section-size="6668",
|
|
total-sent="5632",total-size="9880"@}
|
|
+download,@{section=".text",section-sent="6144",section-size="6668",
|
|
total-sent="6144",total-size="9880"@}
|
|
+download,@{section=".text",section-sent="6656",section-size="6668",
|
|
total-sent="6656",total-size="9880"@}
|
|
+download,@{section=".init",section-size="28",total-size="9880"@}
|
|
+download,@{section=".fini",section-size="28",total-size="9880"@}
|
|
+download,@{section=".data",section-size="3156",total-size="9880"@}
|
|
+download,@{section=".data",section-sent="512",section-size="3156",
|
|
total-sent="7236",total-size="9880"@}
|
|
+download,@{section=".data",section-sent="1024",section-size="3156",
|
|
total-sent="7748",total-size="9880"@}
|
|
+download,@{section=".data",section-sent="1536",section-size="3156",
|
|
total-sent="8260",total-size="9880"@}
|
|
+download,@{section=".data",section-sent="2048",section-size="3156",
|
|
total-sent="8772",total-size="9880"@}
|
|
+download,@{section=".data",section-sent="2560",section-size="3156",
|
|
total-sent="9284",total-size="9880"@}
|
|
+download,@{section=".data",section-sent="3072",section-size="3156",
|
|
total-sent="9796",total-size="9880"@}
|
|
^done,address="0x10004",load-size="9880",transfer-rate="6586",
|
|
write-rate="429"
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
|
|
@ignore
|
|
@subheading The @code{-target-exec-status} Command
|
|
@findex -target-exec-status
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-target-exec-status
|
|
@end smallexample
|
|
|
|
Provide information on the state of the target (whether it is running or
|
|
not, for instance).
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
There's no equivalent @value{GDBN} command.
|
|
|
|
@subsubheading Example
|
|
N.A.
|
|
|
|
|
|
@subheading The @code{-target-list-available-targets} Command
|
|
@findex -target-list-available-targets
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-target-list-available-targets
|
|
@end smallexample
|
|
|
|
List the possible targets to connect to.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} command is @samp{help target}.
|
|
|
|
@subsubheading Example
|
|
N.A.
|
|
|
|
|
|
@subheading The @code{-target-list-current-targets} Command
|
|
@findex -target-list-current-targets
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-target-list-current-targets
|
|
@end smallexample
|
|
|
|
Describe the current target.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding information is printed by @samp{info file} (among
|
|
other things).
|
|
|
|
@subsubheading Example
|
|
N.A.
|
|
|
|
|
|
@subheading The @code{-target-list-parameters} Command
|
|
@findex -target-list-parameters
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-target-list-parameters
|
|
@end smallexample
|
|
|
|
@c ????
|
|
@end ignore
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
No equivalent.
|
|
|
|
@subsubheading Example
|
|
N.A.
|
|
|
|
|
|
@subheading The @code{-target-select} Command
|
|
@findex -target-select
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-target-select @var{type} @var{parameters @dots{}}
|
|
@end smallexample
|
|
|
|
Connect @value{GDBN} to the remote target. This command takes two args:
|
|
|
|
@table @samp
|
|
@item @var{type}
|
|
The type of target, for instance @samp{remote}, etc.
|
|
@item @var{parameters}
|
|
Device names, host names and the like. @xref{Target Commands, ,
|
|
Commands for Managing Targets}, for more details.
|
|
@end table
|
|
|
|
The output is a connection notification, followed by the address at
|
|
which the target program is, in the following form:
|
|
|
|
@smallexample
|
|
^connected,addr="@var{address}",func="@var{function name}",
|
|
args=[@var{arg list}]
|
|
@end smallexample
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} command is @samp{target}.
|
|
|
|
@subsubheading Example
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-target-select remote /dev/ttya
|
|
^connected,addr="0xfe00a300",func="??",args=[]
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
@c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
@node GDB/MI File Transfer Commands
|
|
@section @sc{gdb/mi} File Transfer Commands
|
|
|
|
|
|
@subheading The @code{-target-file-put} Command
|
|
@findex -target-file-put
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-target-file-put @var{hostfile} @var{targetfile}
|
|
@end smallexample
|
|
|
|
Copy file @var{hostfile} from the host system (the machine running
|
|
@value{GDBN}) to @var{targetfile} on the target system.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} command is @samp{remote put}.
|
|
|
|
@subsubheading Example
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-target-file-put localfile remotefile
|
|
^done
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
|
|
@subheading The @code{-target-file-get} Command
|
|
@findex -target-file-get
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-target-file-get @var{targetfile} @var{hostfile}
|
|
@end smallexample
|
|
|
|
Copy file @var{targetfile} from the target system to @var{hostfile}
|
|
on the host system.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} command is @samp{remote get}.
|
|
|
|
@subsubheading Example
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-target-file-get remotefile localfile
|
|
^done
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
|
|
@subheading The @code{-target-file-delete} Command
|
|
@findex -target-file-delete
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-target-file-delete @var{targetfile}
|
|
@end smallexample
|
|
|
|
Delete @var{targetfile} from the target system.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} command is @samp{remote delete}.
|
|
|
|
@subsubheading Example
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-target-file-delete remotefile
|
|
^done
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
|
|
@c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
@node GDB/MI Miscellaneous Commands
|
|
@section Miscellaneous @sc{gdb/mi} Commands
|
|
|
|
@c @subheading -gdb-complete
|
|
|
|
@subheading The @code{-gdb-exit} Command
|
|
@findex -gdb-exit
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-gdb-exit
|
|
@end smallexample
|
|
|
|
Exit @value{GDBN} immediately.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
Approximately corresponds to @samp{quit}.
|
|
|
|
@subsubheading Example
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-gdb-exit
|
|
^exit
|
|
@end smallexample
|
|
|
|
|
|
@ignore
|
|
@subheading The @code{-exec-abort} Command
|
|
@findex -exec-abort
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-exec-abort
|
|
@end smallexample
|
|
|
|
Kill the inferior running program.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} command is @samp{kill}.
|
|
|
|
@subsubheading Example
|
|
N.A.
|
|
@end ignore
|
|
|
|
|
|
@subheading The @code{-gdb-set} Command
|
|
@findex -gdb-set
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-gdb-set
|
|
@end smallexample
|
|
|
|
Set an internal @value{GDBN} variable.
|
|
@c IS THIS A DOLLAR VARIABLE? OR SOMETHING LIKE ANNOTATE ?????
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} command is @samp{set}.
|
|
|
|
@subsubheading Example
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-gdb-set $foo=3
|
|
^done
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
|
|
@subheading The @code{-gdb-show} Command
|
|
@findex -gdb-show
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-gdb-show
|
|
@end smallexample
|
|
|
|
Show the current value of a @value{GDBN} variable.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} command is @samp{show}.
|
|
|
|
@subsubheading Example
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-gdb-show annotate
|
|
^done,value="0"
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
@c @subheading -gdb-source
|
|
|
|
|
|
@subheading The @code{-gdb-version} Command
|
|
@findex -gdb-version
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-gdb-version
|
|
@end smallexample
|
|
|
|
Show version information for @value{GDBN}. Used mostly in testing.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The @value{GDBN} equivalent is @samp{show version}. @value{GDBN} by
|
|
default shows this information when you start an interactive session.
|
|
|
|
@subsubheading Example
|
|
|
|
@c This example modifies the actual output from GDB to avoid overfull
|
|
@c box in TeX.
|
|
@smallexample
|
|
(gdb)
|
|
-gdb-version
|
|
~GNU gdb 5.2.1
|
|
~Copyright 2000 Free Software Foundation, Inc.
|
|
~GDB is free software, covered by the GNU General Public License, and
|
|
~you are welcome to change it and/or distribute copies of it under
|
|
~ certain conditions.
|
|
~Type "show copying" to see the conditions.
|
|
~There is absolutely no warranty for GDB. Type "show warranty" for
|
|
~ details.
|
|
~This GDB was configured as
|
|
"--host=sparc-sun-solaris2.5.1 --target=ppc-eabi".
|
|
^done
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
@subheading The @code{-list-features} Command
|
|
@findex -list-features
|
|
|
|
Returns a list of particular features of the MI protocol that
|
|
this version of gdb implements. A feature can be a command,
|
|
or a new field in an output of some command, or even an
|
|
important bugfix. While a frontend can sometimes detect presence
|
|
of a feature at runtime, it is easier to perform detection at debugger
|
|
startup.
|
|
|
|
The command returns a list of strings, with each string naming an
|
|
available feature. Each returned string is just a name, it does not
|
|
have any internal structure. The list of possible feature names
|
|
is given below.
|
|
|
|
Example output:
|
|
|
|
@smallexample
|
|
(gdb) -list-features
|
|
^done,result=["feature1","feature2"]
|
|
@end smallexample
|
|
|
|
The current list of features is:
|
|
|
|
@table @samp
|
|
@item frozen-varobjs
|
|
Indicates support for the @code{-var-set-frozen} command, as well
|
|
as possible presense of the @code{frozen} field in the output
|
|
of @code{-varobj-create}.
|
|
@item pending-breakpoints
|
|
Indicates support for the @option{-f} option to the @code{-break-insert}
|
|
command.
|
|
@item python
|
|
Indicates Python scripting support, Python-based
|
|
pretty-printing commands, and possible presence of the
|
|
@samp{display_hint} field in the output of @code{-var-list-children}
|
|
@item thread-info
|
|
Indicates support for the @code{-thread-info} command.
|
|
@item data-read-memory-bytes
|
|
Indicates support for the @code{-data-read-memory-bytes} and the
|
|
@code{-data-write-memory-bytes} commands.
|
|
@item breakpoint-notifications
|
|
Indicates that changes to breakpoints and breakpoints created via the
|
|
CLI will be announced via async records.
|
|
@item ada-task-info
|
|
Indicates support for the @code{-ada-task-info} command.
|
|
@end table
|
|
|
|
@subheading The @code{-list-target-features} Command
|
|
@findex -list-target-features
|
|
|
|
Returns a list of particular features that are supported by the
|
|
target. Those features affect the permitted MI commands, but
|
|
unlike the features reported by the @code{-list-features} command, the
|
|
features depend on which target GDB is using at the moment. Whenever
|
|
a target can change, due to commands such as @code{-target-select},
|
|
@code{-target-attach} or @code{-exec-run}, the list of target features
|
|
may change, and the frontend should obtain it again.
|
|
Example output:
|
|
|
|
@smallexample
|
|
(gdb) -list-features
|
|
^done,result=["async"]
|
|
@end smallexample
|
|
|
|
The current list of features is:
|
|
|
|
@table @samp
|
|
@item async
|
|
Indicates that the target is capable of asynchronous command
|
|
execution, which means that @value{GDBN} will accept further commands
|
|
while the target is running.
|
|
|
|
@item reverse
|
|
Indicates that the target is capable of reverse execution.
|
|
@xref{Reverse Execution}, for more information.
|
|
|
|
@end table
|
|
|
|
@subheading The @code{-list-thread-groups} Command
|
|
@findex -list-thread-groups
|
|
|
|
@subheading Synopsis
|
|
|
|
@smallexample
|
|
-list-thread-groups [ --available ] [ --recurse 1 ] [ @var{group} ... ]
|
|
@end smallexample
|
|
|
|
Lists thread groups (@pxref{Thread groups}). When a single thread
|
|
group is passed as the argument, lists the children of that group.
|
|
When several thread group are passed, lists information about those
|
|
thread groups. Without any parameters, lists information about all
|
|
top-level thread groups.
|
|
|
|
Normally, thread groups that are being debugged are reported.
|
|
With the @samp{--available} option, @value{GDBN} reports thread groups
|
|
available on the target.
|
|
|
|
The output of this command may have either a @samp{threads} result or
|
|
a @samp{groups} result. The @samp{thread} result has a list of tuples
|
|
as value, with each tuple describing a thread (@pxref{GDB/MI Thread
|
|
Information}). The @samp{groups} result has a list of tuples as value,
|
|
each tuple describing a thread group. If top-level groups are
|
|
requested (that is, no parameter is passed), or when several groups
|
|
are passed, the output always has a @samp{groups} result. The format
|
|
of the @samp{group} result is described below.
|
|
|
|
To reduce the number of roundtrips it's possible to list thread groups
|
|
together with their children, by passing the @samp{--recurse} option
|
|
and the recursion depth. Presently, only recursion depth of 1 is
|
|
permitted. If this option is present, then every reported thread group
|
|
will also include its children, either as @samp{group} or
|
|
@samp{threads} field.
|
|
|
|
In general, any combination of option and parameters is permitted, with
|
|
the following caveats:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
When a single thread group is passed, the output will typically
|
|
be the @samp{threads} result. Because threads may not contain
|
|
anything, the @samp{recurse} option will be ignored.
|
|
|
|
@item
|
|
When the @samp{--available} option is passed, limited information may
|
|
be available. In particular, the list of threads of a process might
|
|
be inaccessible. Further, specifying specific thread groups might
|
|
not give any performance advantage over listing all thread groups.
|
|
The frontend should assume that @samp{-list-thread-groups --available}
|
|
is always an expensive operation and cache the results.
|
|
|
|
@end itemize
|
|
|
|
The @samp{groups} result is a list of tuples, where each tuple may
|
|
have the following fields:
|
|
|
|
@table @code
|
|
@item id
|
|
Identifier of the thread group. This field is always present.
|
|
The identifier is an opaque string; frontends should not try to
|
|
convert it to an integer, even though it might look like one.
|
|
|
|
@item type
|
|
The type of the thread group. At present, only @samp{process} is a
|
|
valid type.
|
|
|
|
@item pid
|
|
The target-specific process identifier. This field is only present
|
|
for thread groups of type @samp{process} and only if the process exists.
|
|
|
|
@item num_children
|
|
The number of children this thread group has. This field may be
|
|
absent for an available thread group.
|
|
|
|
@item threads
|
|
This field has a list of tuples as value, each tuple describing a
|
|
thread. It may be present if the @samp{--recurse} option is
|
|
specified, and it's actually possible to obtain the threads.
|
|
|
|
@item cores
|
|
This field is a list of integers, each identifying a core that one
|
|
thread of the group is running on. This field may be absent if
|
|
such information is not available.
|
|
|
|
@item executable
|
|
The name of the executable file that corresponds to this thread group.
|
|
The field is only present for thread groups of type @samp{process},
|
|
and only if there is a corresponding executable file.
|
|
|
|
@end table
|
|
|
|
@subheading Example
|
|
|
|
@smallexample
|
|
@value{GDBP}
|
|
-list-thread-groups
|
|
^done,groups=[@{id="17",type="process",pid="yyy",num_children="2"@}]
|
|
-list-thread-groups 17
|
|
^done,threads=[@{id="2",target-id="Thread 0xb7e14b90 (LWP 21257)",
|
|
frame=@{level="0",addr="0xffffe410",func="__kernel_vsyscall",args=[]@},state="running"@},
|
|
@{id="1",target-id="Thread 0xb7e156b0 (LWP 21254)",
|
|
frame=@{level="0",addr="0x0804891f",func="foo",args=[@{name="i",value="10"@}],
|
|
file="/tmp/a.c",fullname="/tmp/a.c",line="158"@},state="running"@}]]
|
|
-list-thread-groups --available
|
|
^done,groups=[@{id="17",type="process",pid="yyy",num_children="2",cores=[1,2]@}]
|
|
-list-thread-groups --available --recurse 1
|
|
^done,groups=[@{id="17", types="process",pid="yyy",num_children="2",cores=[1,2],
|
|
threads=[@{id="1",target-id="Thread 0xb7e14b90",cores=[1]@},
|
|
@{id="2",target-id="Thread 0xb7e14b90",cores=[2]@}]@},..]
|
|
-list-thread-groups --available --recurse 1 17 18
|
|
^done,groups=[@{id="17", types="process",pid="yyy",num_children="2",cores=[1,2],
|
|
threads=[@{id="1",target-id="Thread 0xb7e14b90",cores=[1]@},
|
|
@{id="2",target-id="Thread 0xb7e14b90",cores=[2]@}]@},...]
|
|
@end smallexample
|
|
|
|
@subheading The @code{-info-os} Command
|
|
@findex -info-os
|
|
|
|
@subsubheading Synopsis
|
|
|
|
@smallexample
|
|
-info-os [ @var{type} ]
|
|
@end smallexample
|
|
|
|
If no argument is supplied, the command returns a table of available
|
|
operating-system-specific information types. If one of these types is
|
|
supplied as an argument @var{type}, then the command returns a table
|
|
of data of that type.
|
|
|
|
The types of information available depend on the target operating
|
|
system.
|
|
|
|
@subsubheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} command is @samp{info os}.
|
|
|
|
@subsubheading Example
|
|
|
|
When run on a @sc{gnu}/Linux system, the output will look something
|
|
like this:
|
|
|
|
@smallexample
|
|
@value{GDBP}
|
|
-info-os
|
|
^done,OSDataTable=@{nr_rows="9",nr_cols="3",
|
|
hdr=[@{width="10",alignment="-1",col_name="col0",colhdr="Type"@},
|
|
@{width="10",alignment="-1",col_name="col1",colhdr="Description"@},
|
|
@{width="10",alignment="-1",col_name="col2",colhdr="Title"@}],
|
|
body=[item=@{col0="processes",col1="Listing of all processes",
|
|
col2="Processes"@},
|
|
item=@{col0="procgroups",col1="Listing of all process groups",
|
|
col2="Process groups"@},
|
|
item=@{col0="threads",col1="Listing of all threads",
|
|
col2="Threads"@},
|
|
item=@{col0="files",col1="Listing of all file descriptors",
|
|
col2="File descriptors"@},
|
|
item=@{col0="sockets",col1="Listing of all internet-domain sockets",
|
|
col2="Sockets"@},
|
|
item=@{col0="shm",col1="Listing of all shared-memory regions",
|
|
col2="Shared-memory regions"@},
|
|
item=@{col0="semaphores",col1="Listing of all semaphores",
|
|
col2="Semaphores"@},
|
|
item=@{col0="msg",col1="Listing of all message queues",
|
|
col2="Message queues"@},
|
|
item=@{col0="modules",col1="Listing of all loaded kernel modules",
|
|
col2="Kernel modules"@}]@}
|
|
@value{GDBP}
|
|
-info-os processes
|
|
^done,OSDataTable=@{nr_rows="190",nr_cols="4",
|
|
hdr=[@{width="10",alignment="-1",col_name="col0",colhdr="pid"@},
|
|
@{width="10",alignment="-1",col_name="col1",colhdr="user"@},
|
|
@{width="10",alignment="-1",col_name="col2",colhdr="command"@},
|
|
@{width="10",alignment="-1",col_name="col3",colhdr="cores"@}],
|
|
body=[item=@{col0="1",col1="root",col2="/sbin/init",col3="0"@},
|
|
item=@{col0="2",col1="root",col2="[kthreadd]",col3="1"@},
|
|
item=@{col0="3",col1="root",col2="[ksoftirqd/0]",col3="0"@},
|
|
...
|
|
item=@{col0="26446",col1="stan",col2="bash",col3="0"@},
|
|
item=@{col0="28152",col1="stan",col2="bash",col3="1"@}]@}
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
(Note that the MI output here includes a @code{"Title"} column that
|
|
does not appear in command-line @code{info os}; this column is useful
|
|
for MI clients that want to enumerate the types of data, such as in a
|
|
popup menu, but is needless clutter on the command line, and
|
|
@code{info os} omits it.)
|
|
|
|
@subheading The @code{-add-inferior} Command
|
|
@findex -add-inferior
|
|
|
|
@subheading Synopsis
|
|
|
|
@smallexample
|
|
-add-inferior
|
|
@end smallexample
|
|
|
|
Creates a new inferior (@pxref{Inferiors and Programs}). The created
|
|
inferior is not associated with any executable. Such association may
|
|
be established with the @samp{-file-exec-and-symbols} command
|
|
(@pxref{GDB/MI File Commands}). The command response has a single
|
|
field, @samp{thread-group}, whose value is the identifier of the
|
|
thread group corresponding to the new inferior.
|
|
|
|
@subheading Example
|
|
|
|
@smallexample
|
|
@value{GDBP}
|
|
-add-inferior
|
|
^done,thread-group="i3"
|
|
@end smallexample
|
|
|
|
@subheading The @code{-interpreter-exec} Command
|
|
@findex -interpreter-exec
|
|
|
|
@subheading Synopsis
|
|
|
|
@smallexample
|
|
-interpreter-exec @var{interpreter} @var{command}
|
|
@end smallexample
|
|
@anchor{-interpreter-exec}
|
|
|
|
Execute the specified @var{command} in the given @var{interpreter}.
|
|
|
|
@subheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} command is @samp{interpreter-exec}.
|
|
|
|
@subheading Example
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-interpreter-exec console "break main"
|
|
&"During symbol reading, couldn't parse type; debugger out of date?.\n"
|
|
&"During symbol reading, bad structure-type format.\n"
|
|
~"Breakpoint 1 at 0x8074fc6: file ../../src/gdb/main.c, line 743.\n"
|
|
^done
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
@subheading The @code{-inferior-tty-set} Command
|
|
@findex -inferior-tty-set
|
|
|
|
@subheading Synopsis
|
|
|
|
@smallexample
|
|
-inferior-tty-set /dev/pts/1
|
|
@end smallexample
|
|
|
|
Set terminal for future runs of the program being debugged.
|
|
|
|
@subheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} command is @samp{set inferior-tty} /dev/pts/1.
|
|
|
|
@subheading Example
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-inferior-tty-set /dev/pts/1
|
|
^done
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
@subheading The @code{-inferior-tty-show} Command
|
|
@findex -inferior-tty-show
|
|
|
|
@subheading Synopsis
|
|
|
|
@smallexample
|
|
-inferior-tty-show
|
|
@end smallexample
|
|
|
|
Show terminal for future runs of program being debugged.
|
|
|
|
@subheading @value{GDBN} Command
|
|
|
|
The corresponding @value{GDBN} command is @samp{show inferior-tty}.
|
|
|
|
@subheading Example
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-inferior-tty-set /dev/pts/1
|
|
^done
|
|
(gdb)
|
|
-inferior-tty-show
|
|
^done,inferior_tty_terminal="/dev/pts/1"
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
@subheading The @code{-enable-timings} Command
|
|
@findex -enable-timings
|
|
|
|
@subheading Synopsis
|
|
|
|
@smallexample
|
|
-enable-timings [yes | no]
|
|
@end smallexample
|
|
|
|
Toggle the printing of the wallclock, user and system times for an MI
|
|
command as a field in its output. This command is to help frontend
|
|
developers optimize the performance of their code. No argument is
|
|
equivalent to @samp{yes}.
|
|
|
|
@subheading @value{GDBN} Command
|
|
|
|
No equivalent.
|
|
|
|
@subheading Example
|
|
|
|
@smallexample
|
|
(gdb)
|
|
-enable-timings
|
|
^done
|
|
(gdb)
|
|
-break-insert main
|
|
^done,bkpt=@{number="1",type="breakpoint",disp="keep",enabled="y",
|
|
addr="0x080484ed",func="main",file="myprog.c",
|
|
fullname="/home/nickrob/myprog.c",line="73",times="0"@},
|
|
time=@{wallclock="0.05185",user="0.00800",system="0.00000"@}
|
|
(gdb)
|
|
-enable-timings no
|
|
^done
|
|
(gdb)
|
|
-exec-run
|
|
^running
|
|
(gdb)
|
|
*stopped,reason="breakpoint-hit",disp="keep",bkptno="1",thread-id="0",
|
|
frame=@{addr="0x080484ed",func="main",args=[@{name="argc",value="1"@},
|
|
@{name="argv",value="0xbfb60364"@}],file="myprog.c",
|
|
fullname="/home/nickrob/myprog.c",line="73"@}
|
|
(gdb)
|
|
@end smallexample
|
|
|
|
@node Annotations
|
|
@chapter @value{GDBN} Annotations
|
|
|
|
This chapter describes annotations in @value{GDBN}. Annotations were
|
|
designed to interface @value{GDBN} to graphical user interfaces or other
|
|
similar programs which want to interact with @value{GDBN} at a
|
|
relatively high level.
|
|
|
|
The annotation mechanism has largely been superseded by @sc{gdb/mi}
|
|
(@pxref{GDB/MI}).
|
|
|
|
@ignore
|
|
This is Edition @value{EDITION}, @value{DATE}.
|
|
@end ignore
|
|
|
|
@menu
|
|
* Annotations Overview:: What annotations are; the general syntax.
|
|
* Server Prefix:: Issuing a command without affecting user state.
|
|
* Prompting:: Annotations marking @value{GDBN}'s need for input.
|
|
* Errors:: Annotations for error messages.
|
|
* Invalidation:: Some annotations describe things now invalid.
|
|
* Annotations for Running::
|
|
Whether the program is running, how it stopped, etc.
|
|
* Source Annotations:: Annotations describing source code.
|
|
@end menu
|
|
|
|
@node Annotations Overview
|
|
@section What is an Annotation?
|
|
@cindex annotations
|
|
|
|
Annotations start with a newline character, two @samp{control-z}
|
|
characters, and the name of the annotation. If there is no additional
|
|
information associated with this annotation, the name of the annotation
|
|
is followed immediately by a newline. If there is additional
|
|
information, the name of the annotation is followed by a space, the
|
|
additional information, and a newline. The additional information
|
|
cannot contain newline characters.
|
|
|
|
Any output not beginning with a newline and two @samp{control-z}
|
|
characters denotes literal output from @value{GDBN}. Currently there is
|
|
no need for @value{GDBN} to output a newline followed by two
|
|
@samp{control-z} characters, but if there was such a need, the
|
|
annotations could be extended with an @samp{escape} annotation which
|
|
means those three characters as output.
|
|
|
|
The annotation @var{level}, which is specified using the
|
|
@option{--annotate} command line option (@pxref{Mode Options}), controls
|
|
how much information @value{GDBN} prints together with its prompt,
|
|
values of expressions, source lines, and other types of output. Level 0
|
|
is for no annotations, level 1 is for use when @value{GDBN} is run as a
|
|
subprocess of @sc{gnu} Emacs, level 3 is the maximum annotation suitable
|
|
for programs that control @value{GDBN}, and level 2 annotations have
|
|
been made obsolete (@pxref{Limitations, , Limitations of the Annotation
|
|
Interface, annotate, GDB's Obsolete Annotations}).
|
|
|
|
@table @code
|
|
@kindex set annotate
|
|
@item set annotate @var{level}
|
|
The @value{GDBN} command @code{set annotate} sets the level of
|
|
annotations to the specified @var{level}.
|
|
|
|
@item show annotate
|
|
@kindex show annotate
|
|
Show the current annotation level.
|
|
@end table
|
|
|
|
This chapter describes level 3 annotations.
|
|
|
|
A simple example of starting up @value{GDBN} with annotations is:
|
|
|
|
@smallexample
|
|
$ @kbd{gdb --annotate=3}
|
|
GNU gdb 6.0
|
|
Copyright 2003 Free Software Foundation, Inc.
|
|
GDB is free software, covered by the GNU General Public License,
|
|
and you are welcome to change it and/or distribute copies of it
|
|
under certain conditions.
|
|
Type "show copying" to see the conditions.
|
|
There is absolutely no warranty for GDB. Type "show warranty"
|
|
for details.
|
|
This GDB was configured as "i386-pc-linux-gnu"
|
|
|
|
^Z^Zpre-prompt
|
|
(@value{GDBP})
|
|
^Z^Zprompt
|
|
@kbd{quit}
|
|
|
|
^Z^Zpost-prompt
|
|
$
|
|
@end smallexample
|
|
|
|
Here @samp{quit} is input to @value{GDBN}; the rest is output from
|
|
@value{GDBN}. The three lines beginning @samp{^Z^Z} (where @samp{^Z}
|
|
denotes a @samp{control-z} character) are annotations; the rest is
|
|
output from @value{GDBN}.
|
|
|
|
@node Server Prefix
|
|
@section The Server Prefix
|
|
@cindex server prefix
|
|
|
|
If you prefix a command with @samp{server } then it will not affect
|
|
the command history, nor will it affect @value{GDBN}'s notion of which
|
|
command to repeat if @key{RET} is pressed on a line by itself. This
|
|
means that commands can be run behind a user's back by a front-end in
|
|
a transparent manner.
|
|
|
|
The @code{server } prefix does not affect the recording of values into
|
|
the value history; to print a value without recording it into the
|
|
value history, use the @code{output} command instead of the
|
|
@code{print} command.
|
|
|
|
Using this prefix also disables confirmation requests
|
|
(@pxref{confirmation requests}).
|
|
|
|
@node Prompting
|
|
@section Annotation for @value{GDBN} Input
|
|
|
|
@cindex annotations for prompts
|
|
When @value{GDBN} prompts for input, it annotates this fact so it is possible
|
|
to know when to send output, when the output from a given command is
|
|
over, etc.
|
|
|
|
Different kinds of input each have a different @dfn{input type}. Each
|
|
input type has three annotations: a @code{pre-} annotation, which
|
|
denotes the beginning of any prompt which is being output, a plain
|
|
annotation, which denotes the end of the prompt, and then a @code{post-}
|
|
annotation which denotes the end of any echo which may (or may not) be
|
|
associated with the input. For example, the @code{prompt} input type
|
|
features the following annotations:
|
|
|
|
@smallexample
|
|
^Z^Zpre-prompt
|
|
^Z^Zprompt
|
|
^Z^Zpost-prompt
|
|
@end smallexample
|
|
|
|
The input types are
|
|
|
|
@table @code
|
|
@findex pre-prompt annotation
|
|
@findex prompt annotation
|
|
@findex post-prompt annotation
|
|
@item prompt
|
|
When @value{GDBN} is prompting for a command (the main @value{GDBN} prompt).
|
|
|
|
@findex pre-commands annotation
|
|
@findex commands annotation
|
|
@findex post-commands annotation
|
|
@item commands
|
|
When @value{GDBN} prompts for a set of commands, like in the @code{commands}
|
|
command. The annotations are repeated for each command which is input.
|
|
|
|
@findex pre-overload-choice annotation
|
|
@findex overload-choice annotation
|
|
@findex post-overload-choice annotation
|
|
@item overload-choice
|
|
When @value{GDBN} wants the user to select between various overloaded functions.
|
|
|
|
@findex pre-query annotation
|
|
@findex query annotation
|
|
@findex post-query annotation
|
|
@item query
|
|
When @value{GDBN} wants the user to confirm a potentially dangerous operation.
|
|
|
|
@findex pre-prompt-for-continue annotation
|
|
@findex prompt-for-continue annotation
|
|
@findex post-prompt-for-continue annotation
|
|
@item prompt-for-continue
|
|
When @value{GDBN} is asking the user to press return to continue. Note: Don't
|
|
expect this to work well; instead use @code{set height 0} to disable
|
|
prompting. This is because the counting of lines is buggy in the
|
|
presence of annotations.
|
|
@end table
|
|
|
|
@node Errors
|
|
@section Errors
|
|
@cindex annotations for errors, warnings and interrupts
|
|
|
|
@findex quit annotation
|
|
@smallexample
|
|
^Z^Zquit
|
|
@end smallexample
|
|
|
|
This annotation occurs right before @value{GDBN} responds to an interrupt.
|
|
|
|
@findex error annotation
|
|
@smallexample
|
|
^Z^Zerror
|
|
@end smallexample
|
|
|
|
This annotation occurs right before @value{GDBN} responds to an error.
|
|
|
|
Quit and error annotations indicate that any annotations which @value{GDBN} was
|
|
in the middle of may end abruptly. For example, if a
|
|
@code{value-history-begin} annotation is followed by a @code{error}, one
|
|
cannot expect to receive the matching @code{value-history-end}. One
|
|
cannot expect not to receive it either, however; an error annotation
|
|
does not necessarily mean that @value{GDBN} is immediately returning all the way
|
|
to the top level.
|
|
|
|
@findex error-begin annotation
|
|
A quit or error annotation may be preceded by
|
|
|
|
@smallexample
|
|
^Z^Zerror-begin
|
|
@end smallexample
|
|
|
|
Any output between that and the quit or error annotation is the error
|
|
message.
|
|
|
|
Warning messages are not yet annotated.
|
|
@c If we want to change that, need to fix warning(), type_error(),
|
|
@c range_error(), and possibly other places.
|
|
|
|
@node Invalidation
|
|
@section Invalidation Notices
|
|
|
|
@cindex annotations for invalidation messages
|
|
The following annotations say that certain pieces of state may have
|
|
changed.
|
|
|
|
@table @code
|
|
@findex frames-invalid annotation
|
|
@item ^Z^Zframes-invalid
|
|
|
|
The frames (for example, output from the @code{backtrace} command) may
|
|
have changed.
|
|
|
|
@findex breakpoints-invalid annotation
|
|
@item ^Z^Zbreakpoints-invalid
|
|
|
|
The breakpoints may have changed. For example, the user just added or
|
|
deleted a breakpoint.
|
|
@end table
|
|
|
|
@node Annotations for Running
|
|
@section Running the Program
|
|
@cindex annotations for running programs
|
|
|
|
@findex starting annotation
|
|
@findex stopping annotation
|
|
When the program starts executing due to a @value{GDBN} command such as
|
|
@code{step} or @code{continue},
|
|
|
|
@smallexample
|
|
^Z^Zstarting
|
|
@end smallexample
|
|
|
|
is output. When the program stops,
|
|
|
|
@smallexample
|
|
^Z^Zstopped
|
|
@end smallexample
|
|
|
|
is output. Before the @code{stopped} annotation, a variety of
|
|
annotations describe how the program stopped.
|
|
|
|
@table @code
|
|
@findex exited annotation
|
|
@item ^Z^Zexited @var{exit-status}
|
|
The program exited, and @var{exit-status} is the exit status (zero for
|
|
successful exit, otherwise nonzero).
|
|
|
|
@findex signalled annotation
|
|
@findex signal-name annotation
|
|
@findex signal-name-end annotation
|
|
@findex signal-string annotation
|
|
@findex signal-string-end annotation
|
|
@item ^Z^Zsignalled
|
|
The program exited with a signal. After the @code{^Z^Zsignalled}, the
|
|
annotation continues:
|
|
|
|
@smallexample
|
|
@var{intro-text}
|
|
^Z^Zsignal-name
|
|
@var{name}
|
|
^Z^Zsignal-name-end
|
|
@var{middle-text}
|
|
^Z^Zsignal-string
|
|
@var{string}
|
|
^Z^Zsignal-string-end
|
|
@var{end-text}
|
|
@end smallexample
|
|
|
|
@noindent
|
|
where @var{name} is the name of the signal, such as @code{SIGILL} or
|
|
@code{SIGSEGV}, and @var{string} is the explanation of the signal, such
|
|
as @code{Illegal Instruction} or @code{Segmentation fault}.
|
|
@var{intro-text}, @var{middle-text}, and @var{end-text} are for the
|
|
user's benefit and have no particular format.
|
|
|
|
@findex signal annotation
|
|
@item ^Z^Zsignal
|
|
The syntax of this annotation is just like @code{signalled}, but @value{GDBN} is
|
|
just saying that the program received the signal, not that it was
|
|
terminated with it.
|
|
|
|
@findex breakpoint annotation
|
|
@item ^Z^Zbreakpoint @var{number}
|
|
The program hit breakpoint number @var{number}.
|
|
|
|
@findex watchpoint annotation
|
|
@item ^Z^Zwatchpoint @var{number}
|
|
The program hit watchpoint number @var{number}.
|
|
@end table
|
|
|
|
@node Source Annotations
|
|
@section Displaying Source
|
|
@cindex annotations for source display
|
|
|
|
@findex source annotation
|
|
The following annotation is used instead of displaying source code:
|
|
|
|
@smallexample
|
|
^Z^Zsource @var{filename}:@var{line}:@var{character}:@var{middle}:@var{addr}
|
|
@end smallexample
|
|
|
|
where @var{filename} is an absolute file name indicating which source
|
|
file, @var{line} is the line number within that file (where 1 is the
|
|
first line in the file), @var{character} is the character position
|
|
within the file (where 0 is the first character in the file) (for most
|
|
debug formats this will necessarily point to the beginning of a line),
|
|
@var{middle} is @samp{middle} if @var{addr} is in the middle of the
|
|
line, or @samp{beg} if @var{addr} is at the beginning of the line, and
|
|
@var{addr} is the address in the target program associated with the
|
|
source which is being displayed. @var{addr} is in the form @samp{0x}
|
|
followed by one or more lowercase hex digits (note that this does not
|
|
depend on the language).
|
|
|
|
@node JIT Interface
|
|
@chapter JIT Compilation Interface
|
|
@cindex just-in-time compilation
|
|
@cindex JIT compilation interface
|
|
|
|
This chapter documents @value{GDBN}'s @dfn{just-in-time} (JIT) compilation
|
|
interface. A JIT compiler is a program or library that generates native
|
|
executable code at runtime and executes it, usually in order to achieve good
|
|
performance while maintaining platform independence.
|
|
|
|
Programs that use JIT compilation are normally difficult to debug because
|
|
portions of their code are generated at runtime, instead of being loaded from
|
|
object files, which is where @value{GDBN} normally finds the program's symbols
|
|
and debug information. In order to debug programs that use JIT compilation,
|
|
@value{GDBN} has an interface that allows the program to register in-memory
|
|
symbol files with @value{GDBN} at runtime.
|
|
|
|
If you are using @value{GDBN} to debug a program that uses this interface, then
|
|
it should work transparently so long as you have not stripped the binary. If
|
|
you are developing a JIT compiler, then the interface is documented in the rest
|
|
of this chapter. At this time, the only known client of this interface is the
|
|
LLVM JIT.
|
|
|
|
Broadly speaking, the JIT interface mirrors the dynamic loader interface. The
|
|
JIT compiler communicates with @value{GDBN} by writing data into a global
|
|
variable and calling a fuction at a well-known symbol. When @value{GDBN}
|
|
attaches, it reads a linked list of symbol files from the global variable to
|
|
find existing code, and puts a breakpoint in the function so that it can find
|
|
out about additional code.
|
|
|
|
@menu
|
|
* Declarations:: Relevant C struct declarations
|
|
* Registering Code:: Steps to register code
|
|
* Unregistering Code:: Steps to unregister code
|
|
* Custom Debug Info:: Emit debug information in a custom format
|
|
@end menu
|
|
|
|
@node Declarations
|
|
@section JIT Declarations
|
|
|
|
These are the relevant struct declarations that a C program should include to
|
|
implement the interface:
|
|
|
|
@smallexample
|
|
typedef enum
|
|
@{
|
|
JIT_NOACTION = 0,
|
|
JIT_REGISTER_FN,
|
|
JIT_UNREGISTER_FN
|
|
@} jit_actions_t;
|
|
|
|
struct jit_code_entry
|
|
@{
|
|
struct jit_code_entry *next_entry;
|
|
struct jit_code_entry *prev_entry;
|
|
const char *symfile_addr;
|
|
uint64_t symfile_size;
|
|
@};
|
|
|
|
struct jit_descriptor
|
|
@{
|
|
uint32_t version;
|
|
/* This type should be jit_actions_t, but we use uint32_t
|
|
to be explicit about the bitwidth. */
|
|
uint32_t action_flag;
|
|
struct jit_code_entry *relevant_entry;
|
|
struct jit_code_entry *first_entry;
|
|
@};
|
|
|
|
/* GDB puts a breakpoint in this function. */
|
|
void __attribute__((noinline)) __jit_debug_register_code() @{ @};
|
|
|
|
/* Make sure to specify the version statically, because the
|
|
debugger may check the version before we can set it. */
|
|
struct jit_descriptor __jit_debug_descriptor = @{ 1, 0, 0, 0 @};
|
|
@end smallexample
|
|
|
|
If the JIT is multi-threaded, then it is important that the JIT synchronize any
|
|
modifications to this global data properly, which can easily be done by putting
|
|
a global mutex around modifications to these structures.
|
|
|
|
@node Registering Code
|
|
@section Registering Code
|
|
|
|
To register code with @value{GDBN}, the JIT should follow this protocol:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
Generate an object file in memory with symbols and other desired debug
|
|
information. The file must include the virtual addresses of the sections.
|
|
|
|
@item
|
|
Create a code entry for the file, which gives the start and size of the symbol
|
|
file.
|
|
|
|
@item
|
|
Add it to the linked list in the JIT descriptor.
|
|
|
|
@item
|
|
Point the relevant_entry field of the descriptor at the entry.
|
|
|
|
@item
|
|
Set @code{action_flag} to @code{JIT_REGISTER} and call
|
|
@code{__jit_debug_register_code}.
|
|
@end itemize
|
|
|
|
When @value{GDBN} is attached and the breakpoint fires, @value{GDBN} uses the
|
|
@code{relevant_entry} pointer so it doesn't have to walk the list looking for
|
|
new code. However, the linked list must still be maintained in order to allow
|
|
@value{GDBN} to attach to a running process and still find the symbol files.
|
|
|
|
@node Unregistering Code
|
|
@section Unregistering Code
|
|
|
|
If code is freed, then the JIT should use the following protocol:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
Remove the code entry corresponding to the code from the linked list.
|
|
|
|
@item
|
|
Point the @code{relevant_entry} field of the descriptor at the code entry.
|
|
|
|
@item
|
|
Set @code{action_flag} to @code{JIT_UNREGISTER} and call
|
|
@code{__jit_debug_register_code}.
|
|
@end itemize
|
|
|
|
If the JIT frees or recompiles code without unregistering it, then @value{GDBN}
|
|
and the JIT will leak the memory used for the associated symbol files.
|
|
|
|
@node Custom Debug Info
|
|
@section Custom Debug Info
|
|
@cindex custom JIT debug info
|
|
@cindex JIT debug info reader
|
|
|
|
Generating debug information in platform-native file formats (like ELF
|
|
or COFF) may be an overkill for JIT compilers; especially if all the
|
|
debug info is used for is displaying a meaningful backtrace. The
|
|
issue can be resolved by having the JIT writers decide on a debug info
|
|
format and also provide a reader that parses the debug info generated
|
|
by the JIT compiler. This section gives a brief overview on writing
|
|
such a parser. More specific details can be found in the source file
|
|
@file{gdb/jit-reader.in}, which is also installed as a header at
|
|
@file{@var{includedir}/gdb/jit-reader.h} for easy inclusion.
|
|
|
|
The reader is implemented as a shared object (so this functionality is
|
|
not available on platforms which don't allow loading shared objects at
|
|
runtime). Two @value{GDBN} commands, @code{jit-reader-load} and
|
|
@code{jit-reader-unload} are provided, to be used to load and unload
|
|
the readers from a preconfigured directory. Once loaded, the shared
|
|
object is used the parse the debug information emitted by the JIT
|
|
compiler.
|
|
|
|
@menu
|
|
* Using JIT Debug Info Readers:: How to use supplied readers correctly
|
|
* Writing JIT Debug Info Readers:: Creating a debug-info reader
|
|
@end menu
|
|
|
|
@node Using JIT Debug Info Readers
|
|
@subsection Using JIT Debug Info Readers
|
|
@kindex jit-reader-load
|
|
@kindex jit-reader-unload
|
|
|
|
Readers can be loaded and unloaded using the @code{jit-reader-load}
|
|
and @code{jit-reader-unload} commands.
|
|
|
|
@table @code
|
|
@item jit-reader-load @var{reader-name}
|
|
Load the JIT reader named @var{reader-name}. On a UNIX system, this
|
|
will usually load @file{@var{libdir}/gdb/@var{reader-name}}, where
|
|
@var{libdir} is the system library directory, usually
|
|
@file{/usr/local/lib}. Only one reader can be active at a time;
|
|
trying to load a second reader when one is already loaded will result
|
|
in @value{GDBN} reporting an error. A new JIT reader can be loaded by
|
|
first unloading the current one using @code{jit-reader-load} and then
|
|
invoking @code{jit-reader-load}.
|
|
|
|
@item jit-reader-unload
|
|
Unload the currently loaded JIT reader.
|
|
|
|
@end table
|
|
|
|
@node Writing JIT Debug Info Readers
|
|
@subsection Writing JIT Debug Info Readers
|
|
@cindex writing JIT debug info readers
|
|
|
|
As mentioned, a reader is essentially a shared object conforming to a
|
|
certain ABI. This ABI is described in @file{jit-reader.h}.
|
|
|
|
@file{jit-reader.h} defines the structures, macros and functions
|
|
required to write a reader. It is installed (along with
|
|
@value{GDBN}), in @file{@var{includedir}/gdb} where @var{includedir} is
|
|
the system include directory.
|
|
|
|
Readers need to be released under a GPL compatible license. A reader
|
|
can be declared as released under such a license by placing the macro
|
|
@code{GDB_DECLARE_GPL_COMPATIBLE_READER} in a source file.
|
|
|
|
The entry point for readers is the symbol @code{gdb_init_reader},
|
|
which is expected to be a function with the prototype
|
|
|
|
@findex gdb_init_reader
|
|
@smallexample
|
|
extern struct gdb_reader_funcs *gdb_init_reader (void);
|
|
@end smallexample
|
|
|
|
@cindex @code{struct gdb_reader_funcs}
|
|
|
|
@code{struct gdb_reader_funcs} contains a set of pointers to callback
|
|
functions. These functions are executed to read the debug info
|
|
generated by the JIT compiler (@code{read}), to unwind stack frames
|
|
(@code{unwind}) and to create canonical frame IDs
|
|
(@code{get_Frame_id}). It also has a callback that is called when the
|
|
reader is being unloaded (@code{destroy}). The struct looks like this
|
|
|
|
@smallexample
|
|
struct gdb_reader_funcs
|
|
@{
|
|
/* Must be set to GDB_READER_INTERFACE_VERSION. */
|
|
int reader_version;
|
|
|
|
/* For use by the reader. */
|
|
void *priv_data;
|
|
|
|
gdb_read_debug_info *read;
|
|
gdb_unwind_frame *unwind;
|
|
gdb_get_frame_id *get_frame_id;
|
|
gdb_destroy_reader *destroy;
|
|
@};
|
|
@end smallexample
|
|
|
|
@cindex @code{struct gdb_symbol_callbacks}
|
|
@cindex @code{struct gdb_unwind_callbacks}
|
|
|
|
The callbacks are provided with another set of callbacks by
|
|
@value{GDBN} to do their job. For @code{read}, these callbacks are
|
|
passed in a @code{struct gdb_symbol_callbacks} and for @code{unwind}
|
|
and @code{get_frame_id}, in a @code{struct gdb_unwind_callbacks}.
|
|
@code{struct gdb_symbol_callbacks} has callbacks to create new object
|
|
files and new symbol tables inside those object files. @code{struct
|
|
gdb_unwind_callbacks} has callbacks to read registers off the current
|
|
frame and to write out the values of the registers in the previous
|
|
frame. Both have a callback (@code{target_read}) to read bytes off the
|
|
target's address space.
|
|
|
|
@node In-Process Agent
|
|
@chapter In-Process Agent
|
|
@cindex debugging agent
|
|
The traditional debugging model is conceptually low-speed, but works fine,
|
|
because most bugs can be reproduced in debugging-mode execution. However,
|
|
as multi-core or many-core processors are becoming mainstream, and
|
|
multi-threaded programs become more and more popular, there should be more
|
|
and more bugs that only manifest themselves at normal-mode execution, for
|
|
example, thread races, because debugger's interference with the program's
|
|
timing may conceal the bugs. On the other hand, in some applications,
|
|
it is not feasible for the debugger to interrupt the program's execution
|
|
long enough for the developer to learn anything helpful about its behavior.
|
|
If the program's correctness depends on its real-time behavior, delays
|
|
introduced by a debugger might cause the program to fail, even when the
|
|
code itself is correct. It is useful to be able to observe the program's
|
|
behavior without interrupting it.
|
|
|
|
Therefore, traditional debugging model is too intrusive to reproduce
|
|
some bugs. In order to reduce the interference with the program, we can
|
|
reduce the number of operations performed by debugger. The
|
|
@dfn{In-Process Agent}, a shared library, is running within the same
|
|
process with inferior, and is able to perform some debugging operations
|
|
itself. As a result, debugger is only involved when necessary, and
|
|
performance of debugging can be improved accordingly. Note that
|
|
interference with program can be reduced but can't be removed completely,
|
|
because the in-process agent will still stop or slow down the program.
|
|
|
|
The in-process agent can interpret and execute Agent Expressions
|
|
(@pxref{Agent Expressions}) during performing debugging operations. The
|
|
agent expressions can be used for different purposes, such as collecting
|
|
data in tracepoints, and condition evaluation in breakpoints.
|
|
|
|
@anchor{Control Agent}
|
|
You can control whether the in-process agent is used as an aid for
|
|
debugging with the following commands:
|
|
|
|
@table @code
|
|
@kindex set agent on
|
|
@item set agent on
|
|
Causes the in-process agent to perform some operations on behalf of the
|
|
debugger. Just which operations requested by the user will be done
|
|
by the in-process agent depends on the its capabilities. For example,
|
|
if you request to evaluate breakpoint conditions in the in-process agent,
|
|
and the in-process agent has such capability as well, then breakpoint
|
|
conditions will be evaluated in the in-process agent.
|
|
|
|
@kindex set agent off
|
|
@item set agent off
|
|
Disables execution of debugging operations by the in-process agent. All
|
|
of the operations will be performed by @value{GDBN}.
|
|
|
|
@kindex show agent
|
|
@item show agent
|
|
Display the current setting of execution of debugging operations by
|
|
the in-process agent.
|
|
@end table
|
|
|
|
@menu
|
|
* In-Process Agent Protocol::
|
|
@end menu
|
|
|
|
@node In-Process Agent Protocol
|
|
@section In-Process Agent Protocol
|
|
@cindex in-process agent protocol
|
|
|
|
The in-process agent is able to communicate with both @value{GDBN} and
|
|
GDBserver (@pxref{In-Process Agent}). This section documents the protocol
|
|
used for communications between @value{GDBN} or GDBserver and the IPA.
|
|
In general, @value{GDBN} or GDBserver sends commands
|
|
(@pxref{IPA Protocol Commands}) and data to in-process agent, and then
|
|
in-process agent replies back with the return result of the command, or
|
|
some other information. The data sent to in-process agent is composed
|
|
of primitive data types, such as 4-byte or 8-byte type, and composite
|
|
types, which are called objects (@pxref{IPA Protocol Objects}).
|
|
|
|
@menu
|
|
* IPA Protocol Objects::
|
|
* IPA Protocol Commands::
|
|
@end menu
|
|
|
|
@node IPA Protocol Objects
|
|
@subsection IPA Protocol Objects
|
|
@cindex ipa protocol objects
|
|
|
|
The commands sent to and results received from agent may contain some
|
|
complex data types called @dfn{objects}.
|
|
|
|
The in-process agent is running on the same machine with @value{GDBN}
|
|
or GDBserver, so it doesn't have to handle as much differences between
|
|
two ends as remote protocol (@pxref{Remote Protocol}) tries to handle.
|
|
However, there are still some differences of two ends in two processes:
|
|
|
|
@enumerate
|
|
@item
|
|
word size. On some 64-bit machines, @value{GDBN} or GDBserver can be
|
|
compiled as a 64-bit executable, while in-process agent is a 32-bit one.
|
|
@item
|
|
ABI. Some machines may have multiple types of ABI, @value{GDBN} or
|
|
GDBserver is compiled with one, and in-process agent is compiled with
|
|
the other one.
|
|
@end enumerate
|
|
|
|
Here are the IPA Protocol Objects:
|
|
|
|
@enumerate
|
|
@item
|
|
agent expression object. It represents an agent expression
|
|
(@pxref{Agent Expressions}).
|
|
@anchor{agent expression object}
|
|
@item
|
|
tracepoint action object. It represents a tracepoint action
|
|
(@pxref{Tracepoint Actions,,Tracepoint Action Lists}) to collect registers,
|
|
memory, static trace data and to evaluate expression.
|
|
@anchor{tracepoint action object}
|
|
@item
|
|
tracepoint object. It represents a tracepoint (@pxref{Tracepoints}).
|
|
@anchor{tracepoint object}
|
|
|
|
@end enumerate
|
|
|
|
The following table describes important attributes of each IPA protocol
|
|
object:
|
|
|
|
@multitable @columnfractions .30 .20 .50
|
|
@headitem Name @tab Size @tab Description
|
|
@item @emph{agent expression object} @tab @tab
|
|
@item length @tab 4 @tab length of bytes code
|
|
@item byte code @tab @var{length} @tab contents of byte code
|
|
@item @emph{tracepoint action for collecting memory} @tab @tab
|
|
@item 'M' @tab 1 @tab type of tracepoint action
|
|
@item addr @tab 8 @tab if @var{basereg} is @samp{-1}, @var{addr} is the
|
|
address of the lowest byte to collect, otherwise @var{addr} is the offset
|
|
of @var{basereg} for memory collecting.
|
|
@item len @tab 8 @tab length of memory for collecting
|
|
@item basereg @tab 4 @tab the register number containing the starting
|
|
memory address for collecting.
|
|
@item @emph{tracepoint action for collecting registers} @tab @tab
|
|
@item 'R' @tab 1 @tab type of tracepoint action
|
|
@item @emph{tracepoint action for collecting static trace data} @tab @tab
|
|
@item 'L' @tab 1 @tab type of tracepoint action
|
|
@item @emph{tracepoint action for expression evaluation} @tab @tab
|
|
@item 'X' @tab 1 @tab type of tracepoint action
|
|
@item agent expression @tab length of @tab @ref{agent expression object}
|
|
@item @emph{tracepoint object} @tab @tab
|
|
@item number @tab 4 @tab number of tracepoint
|
|
@item address @tab 8 @tab address of tracepoint inserted on
|
|
@item type @tab 4 @tab type of tracepoint
|
|
@item enabled @tab 1 @tab enable or disable of tracepoint
|
|
@item step_count @tab 8 @tab step
|
|
@item pass_count @tab 8 @tab pass
|
|
@item numactions @tab 4 @tab number of tracepoint actions
|
|
@item hit count @tab 8 @tab hit count
|
|
@item trace frame usage @tab 8 @tab trace frame usage
|
|
@item compiled_cond @tab 8 @tab compiled condition
|
|
@item orig_size @tab 8 @tab orig size
|
|
@item condition @tab 4 if condition is NULL otherwise length of
|
|
@ref{agent expression object}
|
|
@tab zero if condition is NULL, otherwise is
|
|
@ref{agent expression object}
|
|
@item actions @tab variable
|
|
@tab numactions number of @ref{tracepoint action object}
|
|
@end multitable
|
|
|
|
@node IPA Protocol Commands
|
|
@subsection IPA Protocol Commands
|
|
@cindex ipa protocol commands
|
|
|
|
The spaces in each command are delimiters to ease reading this commands
|
|
specification. They don't exist in real commands.
|
|
|
|
@table @samp
|
|
|
|
@item FastTrace:@var{tracepoint_object} @var{gdb_jump_pad_head}
|
|
Installs a new fast tracepoint described by @var{tracepoint_object}
|
|
(@pxref{tracepoint object}). @var{gdb_jump_pad_head}, 8-byte long, is the
|
|
head of @dfn{jumppad}, which is used to jump to data collection routine
|
|
in IPA finally.
|
|
|
|
Replies:
|
|
@table @samp
|
|
@item OK @var{target_address} @var{gdb_jump_pad_head} @var{fjump_size} @var{fjump}
|
|
@var{target_address} is address of tracepoint in the inferior.
|
|
@var{gdb_jump_pad_head} is updated head of jumppad. Both of
|
|
@var{target_address} and @var{gdb_jump_pad_head} are 8-byte long.
|
|
@var{fjump} contains a sequence of instructions jump to jumppad entry.
|
|
@var{fjump_size}, 4-byte long, is the size of @var{fjump}.
|
|
@item E @var{NN}
|
|
for an error
|
|
|
|
@end table
|
|
|
|
@item close
|
|
Closes the in-process agent. This command is sent when @value{GDBN} or GDBserver
|
|
is about to kill inferiors.
|
|
|
|
@item qTfSTM
|
|
@xref{qTfSTM}.
|
|
@item qTsSTM
|
|
@xref{qTsSTM}.
|
|
@item qTSTMat
|
|
@xref{qTSTMat}.
|
|
@item probe_marker_at:@var{address}
|
|
Asks in-process agent to probe the marker at @var{address}.
|
|
|
|
Replies:
|
|
@table @samp
|
|
@item E @var{NN}
|
|
for an error
|
|
@end table
|
|
@item unprobe_marker_at:@var{address}
|
|
Asks in-process agent to unprobe the marker at @var{address}.
|
|
@end table
|
|
|
|
@node GDB Bugs
|
|
@chapter Reporting Bugs in @value{GDBN}
|
|
@cindex bugs in @value{GDBN}
|
|
@cindex reporting bugs in @value{GDBN}
|
|
|
|
Your bug reports play an essential role in making @value{GDBN} reliable.
|
|
|
|
Reporting a bug may help you by bringing a solution to your problem, or it
|
|
may not. But in any case the principal function of a bug report is to help
|
|
the entire community by making the next version of @value{GDBN} work better. Bug
|
|
reports are your contribution to the maintenance of @value{GDBN}.
|
|
|
|
In order for a bug report to serve its purpose, you must include the
|
|
information that enables us to fix the bug.
|
|
|
|
@menu
|
|
* Bug Criteria:: Have you found a bug?
|
|
* Bug Reporting:: How to report bugs
|
|
@end menu
|
|
|
|
@node Bug Criteria
|
|
@section Have You Found a Bug?
|
|
@cindex bug criteria
|
|
|
|
If you are not sure whether you have found a bug, here are some guidelines:
|
|
|
|
@itemize @bullet
|
|
@cindex fatal signal
|
|
@cindex debugger crash
|
|
@cindex crash of debugger
|
|
@item
|
|
If the debugger gets a fatal signal, for any input whatever, that is a
|
|
@value{GDBN} bug. Reliable debuggers never crash.
|
|
|
|
@cindex error on valid input
|
|
@item
|
|
If @value{GDBN} produces an error message for valid input, that is a
|
|
bug. (Note that if you're cross debugging, the problem may also be
|
|
somewhere in the connection to the target.)
|
|
|
|
@cindex invalid input
|
|
@item
|
|
If @value{GDBN} does not produce an error message for invalid input,
|
|
that is a bug. However, you should note that your idea of
|
|
``invalid input'' might be our idea of ``an extension'' or ``support
|
|
for traditional practice''.
|
|
|
|
@item
|
|
If you are an experienced user of debugging tools, your suggestions
|
|
for improvement of @value{GDBN} are welcome in any case.
|
|
@end itemize
|
|
|
|
@node Bug Reporting
|
|
@section How to Report Bugs
|
|
@cindex bug reports
|
|
@cindex @value{GDBN} bugs, reporting
|
|
|
|
A number of companies and individuals offer support for @sc{gnu} products.
|
|
If you obtained @value{GDBN} from a support organization, we recommend you
|
|
contact that organization first.
|
|
|
|
You can find contact information for many support companies and
|
|
individuals in the file @file{etc/SERVICE} in the @sc{gnu} Emacs
|
|
distribution.
|
|
@c should add a web page ref...
|
|
|
|
@ifset BUGURL
|
|
@ifset BUGURL_DEFAULT
|
|
In any event, we also recommend that you submit bug reports for
|
|
@value{GDBN}. The preferred method is to submit them directly using
|
|
@uref{http://www.gnu.org/software/gdb/bugs/, @value{GDBN}'s Bugs web
|
|
page}. Alternatively, the @email{bug-gdb@@gnu.org, e-mail gateway} can
|
|
be used.
|
|
|
|
@strong{Do not send bug reports to @samp{info-gdb}, or to
|
|
@samp{help-gdb}, or to any newsgroups.} Most users of @value{GDBN} do
|
|
not want to receive bug reports. Those that do have arranged to receive
|
|
@samp{bug-gdb}.
|
|
|
|
The mailing list @samp{bug-gdb} has a newsgroup @samp{gnu.gdb.bug} which
|
|
serves as a repeater. The mailing list and the newsgroup carry exactly
|
|
the same messages. Often people think of posting bug reports to the
|
|
newsgroup instead of mailing them. This appears to work, but it has one
|
|
problem which can be crucial: a newsgroup posting often lacks a mail
|
|
path back to the sender. Thus, if we need to ask for more information,
|
|
we may be unable to reach you. For this reason, it is better to send
|
|
bug reports to the mailing list.
|
|
@end ifset
|
|
@ifclear BUGURL_DEFAULT
|
|
In any event, we also recommend that you submit bug reports for
|
|
@value{GDBN} to @value{BUGURL}.
|
|
@end ifclear
|
|
@end ifset
|
|
|
|
The fundamental principle of reporting bugs usefully is this:
|
|
@strong{report all the facts}. If you are not sure whether to state a
|
|
fact or leave it out, state it!
|
|
|
|
Often people omit facts because they think they know what causes the
|
|
problem and assume that some details do not matter. Thus, you might
|
|
assume that the name of the variable you use in an example does not matter.
|
|
Well, probably it does not, but one cannot be sure. Perhaps the bug is a
|
|
stray memory reference which happens to fetch from the location where that
|
|
name is stored in memory; perhaps, if the name were different, the contents
|
|
of that location would fool the debugger into doing the right thing despite
|
|
the bug. Play it safe and give a specific, complete example. That is the
|
|
easiest thing for you to do, and the most helpful.
|
|
|
|
Keep in mind that the purpose of a bug report is to enable us to fix the
|
|
bug. It may be that the bug has been reported previously, but neither
|
|
you nor we can know that unless your bug report is complete and
|
|
self-contained.
|
|
|
|
Sometimes people give a few sketchy facts and ask, ``Does this ring a
|
|
bell?'' Those bug reports are useless, and we urge everyone to
|
|
@emph{refuse to respond to them} except to chide the sender to report
|
|
bugs properly.
|
|
|
|
To enable us to fix the bug, you should include all these things:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
The version of @value{GDBN}. @value{GDBN} announces it if you start
|
|
with no arguments; you can also print it at any time using @code{show
|
|
version}.
|
|
|
|
Without this, we will not know whether there is any point in looking for
|
|
the bug in the current version of @value{GDBN}.
|
|
|
|
@item
|
|
The type of machine you are using, and the operating system name and
|
|
version number.
|
|
|
|
@item
|
|
What compiler (and its version) was used to compile @value{GDBN}---e.g.@:
|
|
``@value{GCC}--2.8.1''.
|
|
|
|
@item
|
|
What compiler (and its version) was used to compile the program you are
|
|
debugging---e.g.@: ``@value{GCC}--2.8.1'', or ``HP92453-01 A.10.32.03 HP
|
|
C Compiler''. For @value{NGCC}, you can say @kbd{@value{GCC} --version}
|
|
to get this information; for other compilers, see the documentation for
|
|
those compilers.
|
|
|
|
@item
|
|
The command arguments you gave the compiler to compile your example and
|
|
observe the bug. For example, did you use @samp{-O}? To guarantee
|
|
you will not omit something important, list them all. A copy of the
|
|
Makefile (or the output from make) is sufficient.
|
|
|
|
If we were to try to guess the arguments, we would probably guess wrong
|
|
and then we might not encounter the bug.
|
|
|
|
@item
|
|
A complete input script, and all necessary source files, that will
|
|
reproduce the bug.
|
|
|
|
@item
|
|
A description of what behavior you observe that you believe is
|
|
incorrect. For example, ``It gets a fatal signal.''
|
|
|
|
Of course, if the bug is that @value{GDBN} gets a fatal signal, then we
|
|
will certainly notice it. But if the bug is incorrect output, we might
|
|
not notice unless it is glaringly wrong. You might as well not give us
|
|
a chance to make a mistake.
|
|
|
|
Even if the problem you experience is a fatal signal, you should still
|
|
say so explicitly. Suppose something strange is going on, such as, your
|
|
copy of @value{GDBN} is out of synch, or you have encountered a bug in
|
|
the C library on your system. (This has happened!) Your copy might
|
|
crash and ours would not. If you told us to expect a crash, then when
|
|
ours fails to crash, we would know that the bug was not happening for
|
|
us. If you had not told us to expect a crash, then we would not be able
|
|
to draw any conclusion from our observations.
|
|
|
|
@pindex script
|
|
@cindex recording a session script
|
|
To collect all this information, you can use a session recording program
|
|
such as @command{script}, which is available on many Unix systems.
|
|
Just run your @value{GDBN} session inside @command{script} and then
|
|
include the @file{typescript} file with your bug report.
|
|
|
|
Another way to record a @value{GDBN} session is to run @value{GDBN}
|
|
inside Emacs and then save the entire buffer to a file.
|
|
|
|
@item
|
|
If you wish to suggest changes to the @value{GDBN} source, send us context
|
|
diffs. If you even discuss something in the @value{GDBN} source, refer to
|
|
it by context, not by line number.
|
|
|
|
The line numbers in our development sources will not match those in your
|
|
sources. Your line numbers would convey no useful information to us.
|
|
|
|
@end itemize
|
|
|
|
Here are some things that are not necessary:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
A description of the envelope of the bug.
|
|
|
|
Often people who encounter a bug spend a lot of time investigating
|
|
which changes to the input file will make the bug go away and which
|
|
changes will not affect it.
|
|
|
|
This is often time consuming and not very useful, because the way we
|
|
will find the bug is by running a single example under the debugger
|
|
with breakpoints, not by pure deduction from a series of examples.
|
|
We recommend that you save your time for something else.
|
|
|
|
Of course, if you can find a simpler example to report @emph{instead}
|
|
of the original one, that is a convenience for us. Errors in the
|
|
output will be easier to spot, running under the debugger will take
|
|
less time, and so on.
|
|
|
|
However, simplification is not vital; if you do not want to do this,
|
|
report the bug anyway and send us the entire test case you used.
|
|
|
|
@item
|
|
A patch for the bug.
|
|
|
|
A patch for the bug does help us if it is a good one. But do not omit
|
|
the necessary information, such as the test case, on the assumption that
|
|
a patch is all we need. We might see problems with your patch and decide
|
|
to fix the problem another way, or we might not understand it at all.
|
|
|
|
Sometimes with a program as complicated as @value{GDBN} it is very hard to
|
|
construct an example that will make the program follow a certain path
|
|
through the code. If you do not send us the example, we will not be able
|
|
to construct one, so we will not be able to verify that the bug is fixed.
|
|
|
|
And if we cannot understand what bug you are trying to fix, or why your
|
|
patch should be an improvement, we will not install it. A test case will
|
|
help us to understand.
|
|
|
|
@item
|
|
A guess about what the bug is or what it depends on.
|
|
|
|
Such guesses are usually wrong. Even we cannot guess right about such
|
|
things without first using the debugger to find the facts.
|
|
@end itemize
|
|
|
|
@c The readline documentation is distributed with the readline code
|
|
@c and consists of the two following files:
|
|
@c rluser.texi
|
|
@c hsuser.texi
|
|
@c Use -I with makeinfo to point to the appropriate directory,
|
|
@c environment var TEXINPUTS with TeX.
|
|
@ifclear SYSTEM_READLINE
|
|
@include rluser.texi
|
|
@include hsuser.texi
|
|
@end ifclear
|
|
|
|
@node In Memoriam
|
|
@appendix In Memoriam
|
|
|
|
The @value{GDBN} project mourns the loss of the following long-time
|
|
contributors:
|
|
|
|
@table @code
|
|
@item Fred Fish
|
|
Fred was a long-standing contributor to @value{GDBN} (1991-2006), and
|
|
to Free Software in general. Outside of @value{GDBN}, he was known in
|
|
the Amiga world for his series of Fish Disks, and the GeekGadget project.
|
|
|
|
@item Michael Snyder
|
|
Michael was one of the Global Maintainers of the @value{GDBN} project,
|
|
with contributions recorded as early as 1996, until 2011. In addition
|
|
to his day to day participation, he was a large driving force behind
|
|
adding Reverse Debugging to @value{GDBN}.
|
|
@end table
|
|
|
|
Beyond their technical contributions to the project, they were also
|
|
enjoyable members of the Free Software Community. We will miss them.
|
|
|
|
@node Formatting Documentation
|
|
@appendix Formatting Documentation
|
|
|
|
@cindex @value{GDBN} reference card
|
|
@cindex reference card
|
|
The @value{GDBN} 4 release includes an already-formatted reference card, ready
|
|
for printing with PostScript or Ghostscript, in the @file{gdb}
|
|
subdirectory of the main source directory@footnote{In
|
|
@file{gdb-@value{GDBVN}/gdb/refcard.ps} of the version @value{GDBVN}
|
|
release.}. If you can use PostScript or Ghostscript with your printer,
|
|
you can print the reference card immediately with @file{refcard.ps}.
|
|
|
|
The release also includes the source for the reference card. You
|
|
can format it, using @TeX{}, by typing:
|
|
|
|
@smallexample
|
|
make refcard.dvi
|
|
@end smallexample
|
|
|
|
The @value{GDBN} reference card is designed to print in @dfn{landscape}
|
|
mode on US ``letter'' size paper;
|
|
that is, on a sheet 11 inches wide by 8.5 inches
|
|
high. You will need to specify this form of printing as an option to
|
|
your @sc{dvi} output program.
|
|
|
|
@cindex documentation
|
|
|
|
All the documentation for @value{GDBN} comes as part of the machine-readable
|
|
distribution. The documentation is written in Texinfo format, which is
|
|
a documentation system that uses a single source file to produce both
|
|
on-line information and a printed manual. You can use one of the Info
|
|
formatting commands to create the on-line version of the documentation
|
|
and @TeX{} (or @code{texi2roff}) to typeset the printed version.
|
|
|
|
@value{GDBN} includes an already formatted copy of the on-line Info
|
|
version of this manual in the @file{gdb} subdirectory. The main Info
|
|
file is @file{gdb-@value{GDBVN}/gdb/gdb.info}, and it refers to
|
|
subordinate files matching @samp{gdb.info*} in the same directory. If
|
|
necessary, you can print out these files, or read them with any editor;
|
|
but they are easier to read using the @code{info} subsystem in @sc{gnu}
|
|
Emacs or the standalone @code{info} program, available as part of the
|
|
@sc{gnu} Texinfo distribution.
|
|
|
|
If you want to format these Info files yourself, you need one of the
|
|
Info formatting programs, such as @code{texinfo-format-buffer} or
|
|
@code{makeinfo}.
|
|
|
|
If you have @code{makeinfo} installed, and are in the top level
|
|
@value{GDBN} source directory (@file{gdb-@value{GDBVN}}, in the case of
|
|
version @value{GDBVN}), you can make the Info file by typing:
|
|
|
|
@smallexample
|
|
cd gdb
|
|
make gdb.info
|
|
@end smallexample
|
|
|
|
If you want to typeset and print copies of this manual, you need @TeX{},
|
|
a program to print its @sc{dvi} output files, and @file{texinfo.tex}, the
|
|
Texinfo definitions file.
|
|
|
|
@TeX{} is a typesetting program; it does not print files directly, but
|
|
produces output files called @sc{dvi} files. To print a typeset
|
|
document, you need a program to print @sc{dvi} files. If your system
|
|
has @TeX{} installed, chances are it has such a program. The precise
|
|
command to use depends on your system; @kbd{lpr -d} is common; another
|
|
(for PostScript devices) is @kbd{dvips}. The @sc{dvi} print command may
|
|
require a file name without any extension or a @samp{.dvi} extension.
|
|
|
|
@TeX{} also requires a macro definitions file called
|
|
@file{texinfo.tex}. This file tells @TeX{} how to typeset a document
|
|
written in Texinfo format. On its own, @TeX{} cannot either read or
|
|
typeset a Texinfo file. @file{texinfo.tex} is distributed with GDB
|
|
and is located in the @file{gdb-@var{version-number}/texinfo}
|
|
directory.
|
|
|
|
If you have @TeX{} and a @sc{dvi} printer program installed, you can
|
|
typeset and print this manual. First switch to the @file{gdb}
|
|
subdirectory of the main source directory (for example, to
|
|
@file{gdb-@value{GDBVN}/gdb}) and type:
|
|
|
|
@smallexample
|
|
make gdb.dvi
|
|
@end smallexample
|
|
|
|
Then give @file{gdb.dvi} to your @sc{dvi} printing program.
|
|
|
|
@node Installing GDB
|
|
@appendix Installing @value{GDBN}
|
|
@cindex installation
|
|
|
|
@menu
|
|
* Requirements:: Requirements for building @value{GDBN}
|
|
* Running Configure:: Invoking the @value{GDBN} @file{configure} script
|
|
* Separate Objdir:: Compiling @value{GDBN} in another directory
|
|
* Config Names:: Specifying names for hosts and targets
|
|
* Configure Options:: Summary of options for configure
|
|
* System-wide configuration:: Having a system-wide init file
|
|
@end menu
|
|
|
|
@node Requirements
|
|
@section Requirements for Building @value{GDBN}
|
|
@cindex building @value{GDBN}, requirements for
|
|
|
|
Building @value{GDBN} requires various tools and packages to be available.
|
|
Other packages will be used only if they are found.
|
|
|
|
@heading Tools/Packages Necessary for Building @value{GDBN}
|
|
@table @asis
|
|
@item ISO C90 compiler
|
|
@value{GDBN} is written in ISO C90. It should be buildable with any
|
|
working C90 compiler, e.g.@: GCC.
|
|
|
|
@end table
|
|
|
|
@heading Tools/Packages Optional for Building @value{GDBN}
|
|
@table @asis
|
|
@item Expat
|
|
@anchor{Expat}
|
|
@value{GDBN} can use the Expat XML parsing library. This library may be
|
|
included with your operating system distribution; if it is not, you
|
|
can get the latest version from @url{http://expat.sourceforge.net}.
|
|
The @file{configure} script will search for this library in several
|
|
standard locations; if it is installed in an unusual path, you can
|
|
use the @option{--with-libexpat-prefix} option to specify its location.
|
|
|
|
Expat is used for:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
Remote protocol memory maps (@pxref{Memory Map Format})
|
|
@item
|
|
Target descriptions (@pxref{Target Descriptions})
|
|
@item
|
|
Remote shared library lists (@xref{Library List Format},
|
|
or alternatively @pxref{Library List Format for SVR4 Targets})
|
|
@item
|
|
MS-Windows shared libraries (@pxref{Shared Libraries})
|
|
@item
|
|
Traceframe info (@pxref{Traceframe Info Format})
|
|
@end itemize
|
|
|
|
@item zlib
|
|
@cindex compressed debug sections
|
|
@value{GDBN} will use the @samp{zlib} library, if available, to read
|
|
compressed debug sections. Some linkers, such as GNU gold, are capable
|
|
of producing binaries with compressed debug sections. If @value{GDBN}
|
|
is compiled with @samp{zlib}, it will be able to read the debug
|
|
information in such binaries.
|
|
|
|
The @samp{zlib} library is likely included with your operating system
|
|
distribution; if it is not, you can get the latest version from
|
|
@url{http://zlib.net}.
|
|
|
|
@item iconv
|
|
@value{GDBN}'s features related to character sets (@pxref{Character
|
|
Sets}) require a functioning @code{iconv} implementation. If you are
|
|
on a GNU system, then this is provided by the GNU C Library. Some
|
|
other systems also provide a working @code{iconv}.
|
|
|
|
If @value{GDBN} is using the @code{iconv} program which is installed
|
|
in a non-standard place, you will need to tell @value{GDBN} where to find it.
|
|
This is done with @option{--with-iconv-bin} which specifies the
|
|
directory that contains the @code{iconv} program.
|
|
|
|
On systems without @code{iconv}, you can install GNU Libiconv. If you
|
|
have previously installed Libiconv, you can use the
|
|
@option{--with-libiconv-prefix} option to configure.
|
|
|
|
@value{GDBN}'s top-level @file{configure} and @file{Makefile} will
|
|
arrange to build Libiconv if a directory named @file{libiconv} appears
|
|
in the top-most source directory. If Libiconv is built this way, and
|
|
if the operating system does not provide a suitable @code{iconv}
|
|
implementation, then the just-built library will automatically be used
|
|
by @value{GDBN}. One easy way to set this up is to download GNU
|
|
Libiconv, unpack it, and then rename the directory holding the
|
|
Libiconv source code to @samp{libiconv}.
|
|
@end table
|
|
|
|
@node Running Configure
|
|
@section Invoking the @value{GDBN} @file{configure} Script
|
|
@cindex configuring @value{GDBN}
|
|
@value{GDBN} comes with a @file{configure} script that automates the process
|
|
of preparing @value{GDBN} for installation; you can then use @code{make} to
|
|
build the @code{gdb} program.
|
|
@iftex
|
|
@c irrelevant in info file; it's as current as the code it lives with.
|
|
@footnote{If you have a more recent version of @value{GDBN} than @value{GDBVN},
|
|
look at the @file{README} file in the sources; we may have improved the
|
|
installation procedures since publishing this manual.}
|
|
@end iftex
|
|
|
|
The @value{GDBN} distribution includes all the source code you need for
|
|
@value{GDBN} in a single directory, whose name is usually composed by
|
|
appending the version number to @samp{gdb}.
|
|
|
|
For example, the @value{GDBN} version @value{GDBVN} distribution is in the
|
|
@file{gdb-@value{GDBVN}} directory. That directory contains:
|
|
|
|
@table @code
|
|
@item gdb-@value{GDBVN}/configure @r{(and supporting files)}
|
|
script for configuring @value{GDBN} and all its supporting libraries
|
|
|
|
@item gdb-@value{GDBVN}/gdb
|
|
the source specific to @value{GDBN} itself
|
|
|
|
@item gdb-@value{GDBVN}/bfd
|
|
source for the Binary File Descriptor library
|
|
|
|
@item gdb-@value{GDBVN}/include
|
|
@sc{gnu} include files
|
|
|
|
@item gdb-@value{GDBVN}/libiberty
|
|
source for the @samp{-liberty} free software library
|
|
|
|
@item gdb-@value{GDBVN}/opcodes
|
|
source for the library of opcode tables and disassemblers
|
|
|
|
@item gdb-@value{GDBVN}/readline
|
|
source for the @sc{gnu} command-line interface
|
|
|
|
@item gdb-@value{GDBVN}/glob
|
|
source for the @sc{gnu} filename pattern-matching subroutine
|
|
|
|
@item gdb-@value{GDBVN}/mmalloc
|
|
source for the @sc{gnu} memory-mapped malloc package
|
|
@end table
|
|
|
|
The simplest way to configure and build @value{GDBN} is to run @file{configure}
|
|
from the @file{gdb-@var{version-number}} source directory, which in
|
|
this example is the @file{gdb-@value{GDBVN}} directory.
|
|
|
|
First switch to the @file{gdb-@var{version-number}} source directory
|
|
if you are not already in it; then run @file{configure}. Pass the
|
|
identifier for the platform on which @value{GDBN} will run as an
|
|
argument.
|
|
|
|
For example:
|
|
|
|
@smallexample
|
|
cd gdb-@value{GDBVN}
|
|
./configure @var{host}
|
|
make
|
|
@end smallexample
|
|
|
|
@noindent
|
|
where @var{host} is an identifier such as @samp{sun4} or
|
|
@samp{decstation}, that identifies the platform where @value{GDBN} will run.
|
|
(You can often leave off @var{host}; @file{configure} tries to guess the
|
|
correct value by examining your system.)
|
|
|
|
Running @samp{configure @var{host}} and then running @code{make} builds the
|
|
@file{bfd}, @file{readline}, @file{mmalloc}, and @file{libiberty}
|
|
libraries, then @code{gdb} itself. The configured source files, and the
|
|
binaries, are left in the corresponding source directories.
|
|
|
|
@need 750
|
|
@file{configure} is a Bourne-shell (@code{/bin/sh}) script; if your
|
|
system does not recognize this automatically when you run a different
|
|
shell, you may need to run @code{sh} on it explicitly:
|
|
|
|
@smallexample
|
|
sh configure @var{host}
|
|
@end smallexample
|
|
|
|
If you run @file{configure} from a directory that contains source
|
|
directories for multiple libraries or programs, such as the
|
|
@file{gdb-@value{GDBVN}} source directory for version @value{GDBVN},
|
|
@file{configure}
|
|
creates configuration files for every directory level underneath (unless
|
|
you tell it not to, with the @samp{--norecursion} option).
|
|
|
|
You should run the @file{configure} script from the top directory in the
|
|
source tree, the @file{gdb-@var{version-number}} directory. If you run
|
|
@file{configure} from one of the subdirectories, you will configure only
|
|
that subdirectory. That is usually not what you want. In particular,
|
|
if you run the first @file{configure} from the @file{gdb} subdirectory
|
|
of the @file{gdb-@var{version-number}} directory, you will omit the
|
|
configuration of @file{bfd}, @file{readline}, and other sibling
|
|
directories of the @file{gdb} subdirectory. This leads to build errors
|
|
about missing include files such as @file{bfd/bfd.h}.
|
|
|
|
You can install @code{@value{GDBP}} anywhere; it has no hardwired paths.
|
|
However, you should make sure that the shell on your path (named by
|
|
the @samp{SHELL} environment variable) is publicly readable. Remember
|
|
that @value{GDBN} uses the shell to start your program---some systems refuse to
|
|
let @value{GDBN} debug child processes whose programs are not readable.
|
|
|
|
@node Separate Objdir
|
|
@section Compiling @value{GDBN} in Another Directory
|
|
|
|
If you want to run @value{GDBN} versions for several host or target machines,
|
|
you need a different @code{gdb} compiled for each combination of
|
|
host and target. @file{configure} is designed to make this easy by
|
|
allowing you to generate each configuration in a separate subdirectory,
|
|
rather than in the source directory. If your @code{make} program
|
|
handles the @samp{VPATH} feature (@sc{gnu} @code{make} does), running
|
|
@code{make} in each of these directories builds the @code{gdb}
|
|
program specified there.
|
|
|
|
To build @code{gdb} in a separate directory, run @file{configure}
|
|
with the @samp{--srcdir} option to specify where to find the source.
|
|
(You also need to specify a path to find @file{configure}
|
|
itself from your working directory. If the path to @file{configure}
|
|
would be the same as the argument to @samp{--srcdir}, you can leave out
|
|
the @samp{--srcdir} option; it is assumed.)
|
|
|
|
For example, with version @value{GDBVN}, you can build @value{GDBN} in a
|
|
separate directory for a Sun 4 like this:
|
|
|
|
@smallexample
|
|
@group
|
|
cd gdb-@value{GDBVN}
|
|
mkdir ../gdb-sun4
|
|
cd ../gdb-sun4
|
|
../gdb-@value{GDBVN}/configure sun4
|
|
make
|
|
@end group
|
|
@end smallexample
|
|
|
|
When @file{configure} builds a configuration using a remote source
|
|
directory, it creates a tree for the binaries with the same structure
|
|
(and using the same names) as the tree under the source directory. In
|
|
the example, you'd find the Sun 4 library @file{libiberty.a} in the
|
|
directory @file{gdb-sun4/libiberty}, and @value{GDBN} itself in
|
|
@file{gdb-sun4/gdb}.
|
|
|
|
Make sure that your path to the @file{configure} script has just one
|
|
instance of @file{gdb} in it. If your path to @file{configure} looks
|
|
like @file{../gdb-@value{GDBVN}/gdb/configure}, you are configuring only
|
|
one subdirectory of @value{GDBN}, not the whole package. This leads to
|
|
build errors about missing include files such as @file{bfd/bfd.h}.
|
|
|
|
One popular reason to build several @value{GDBN} configurations in separate
|
|
directories is to configure @value{GDBN} for cross-compiling (where
|
|
@value{GDBN} runs on one machine---the @dfn{host}---while debugging
|
|
programs that run on another machine---the @dfn{target}).
|
|
You specify a cross-debugging target by
|
|
giving the @samp{--target=@var{target}} option to @file{configure}.
|
|
|
|
When you run @code{make} to build a program or library, you must run
|
|
it in a configured directory---whatever directory you were in when you
|
|
called @file{configure} (or one of its subdirectories).
|
|
|
|
The @code{Makefile} that @file{configure} generates in each source
|
|
directory also runs recursively. If you type @code{make} in a source
|
|
directory such as @file{gdb-@value{GDBVN}} (or in a separate configured
|
|
directory configured with @samp{--srcdir=@var{dirname}/gdb-@value{GDBVN}}), you
|
|
will build all the required libraries, and then build GDB.
|
|
|
|
When you have multiple hosts or targets configured in separate
|
|
directories, you can run @code{make} on them in parallel (for example,
|
|
if they are NFS-mounted on each of the hosts); they will not interfere
|
|
with each other.
|
|
|
|
@node Config Names
|
|
@section Specifying Names for Hosts and Targets
|
|
|
|
The specifications used for hosts and targets in the @file{configure}
|
|
script are based on a three-part naming scheme, but some short predefined
|
|
aliases are also supported. The full naming scheme encodes three pieces
|
|
of information in the following pattern:
|
|
|
|
@smallexample
|
|
@var{architecture}-@var{vendor}-@var{os}
|
|
@end smallexample
|
|
|
|
For example, you can use the alias @code{sun4} as a @var{host} argument,
|
|
or as the value for @var{target} in a @code{--target=@var{target}}
|
|
option. The equivalent full name is @samp{sparc-sun-sunos4}.
|
|
|
|
The @file{configure} script accompanying @value{GDBN} does not provide
|
|
any query facility to list all supported host and target names or
|
|
aliases. @file{configure} calls the Bourne shell script
|
|
@code{config.sub} to map abbreviations to full names; you can read the
|
|
script, if you wish, or you can use it to test your guesses on
|
|
abbreviations---for example:
|
|
|
|
@smallexample
|
|
% sh config.sub i386-linux
|
|
i386-pc-linux-gnu
|
|
% sh config.sub alpha-linux
|
|
alpha-unknown-linux-gnu
|
|
% sh config.sub hp9k700
|
|
hppa1.1-hp-hpux
|
|
% sh config.sub sun4
|
|
sparc-sun-sunos4.1.1
|
|
% sh config.sub sun3
|
|
m68k-sun-sunos4.1.1
|
|
% sh config.sub i986v
|
|
Invalid configuration `i986v': machine `i986v' not recognized
|
|
@end smallexample
|
|
|
|
@noindent
|
|
@code{config.sub} is also distributed in the @value{GDBN} source
|
|
directory (@file{gdb-@value{GDBVN}}, for version @value{GDBVN}).
|
|
|
|
@node Configure Options
|
|
@section @file{configure} Options
|
|
|
|
Here is a summary of the @file{configure} options and arguments that
|
|
are most often useful for building @value{GDBN}. @file{configure} also has
|
|
several other options not listed here. @inforef{What Configure
|
|
Does,,configure.info}, for a full explanation of @file{configure}.
|
|
|
|
@smallexample
|
|
configure @r{[}--help@r{]}
|
|
@r{[}--prefix=@var{dir}@r{]}
|
|
@r{[}--exec-prefix=@var{dir}@r{]}
|
|
@r{[}--srcdir=@var{dirname}@r{]}
|
|
@r{[}--norecursion@r{]} @r{[}--rm@r{]}
|
|
@r{[}--target=@var{target}@r{]}
|
|
@var{host}
|
|
@end smallexample
|
|
|
|
@noindent
|
|
You may introduce options with a single @samp{-} rather than
|
|
@samp{--} if you prefer; but you may abbreviate option names if you use
|
|
@samp{--}.
|
|
|
|
@table @code
|
|
@item --help
|
|
Display a quick summary of how to invoke @file{configure}.
|
|
|
|
@item --prefix=@var{dir}
|
|
Configure the source to install programs and files under directory
|
|
@file{@var{dir}}.
|
|
|
|
@item --exec-prefix=@var{dir}
|
|
Configure the source to install programs under directory
|
|
@file{@var{dir}}.
|
|
|
|
@c avoid splitting the warning from the explanation:
|
|
@need 2000
|
|
@item --srcdir=@var{dirname}
|
|
@strong{Warning: using this option requires @sc{gnu} @code{make}, or another
|
|
@code{make} that implements the @code{VPATH} feature.}@*
|
|
Use this option to make configurations in directories separate from the
|
|
@value{GDBN} source directories. Among other things, you can use this to
|
|
build (or maintain) several configurations simultaneously, in separate
|
|
directories. @file{configure} writes configuration-specific files in
|
|
the current directory, but arranges for them to use the source in the
|
|
directory @var{dirname}. @file{configure} creates directories under
|
|
the working directory in parallel to the source directories below
|
|
@var{dirname}.
|
|
|
|
@item --norecursion
|
|
Configure only the directory level where @file{configure} is executed; do not
|
|
propagate configuration to subdirectories.
|
|
|
|
@item --target=@var{target}
|
|
Configure @value{GDBN} for cross-debugging programs running on the specified
|
|
@var{target}. Without this option, @value{GDBN} is configured to debug
|
|
programs that run on the same machine (@var{host}) as @value{GDBN} itself.
|
|
|
|
There is no convenient way to generate a list of all available targets.
|
|
|
|
@item @var{host} @dots{}
|
|
Configure @value{GDBN} to run on the specified @var{host}.
|
|
|
|
There is no convenient way to generate a list of all available hosts.
|
|
@end table
|
|
|
|
There are many other options available as well, but they are generally
|
|
needed for special purposes only.
|
|
|
|
@node System-wide configuration
|
|
@section System-wide configuration and settings
|
|
@cindex system-wide init file
|
|
|
|
@value{GDBN} can be configured to have a system-wide init file;
|
|
this file will be read and executed at startup (@pxref{Startup, , What
|
|
@value{GDBN} does during startup}).
|
|
|
|
Here is the corresponding configure option:
|
|
|
|
@table @code
|
|
@item --with-system-gdbinit=@var{file}
|
|
Specify that the default location of the system-wide init file is
|
|
@var{file}.
|
|
@end table
|
|
|
|
If @value{GDBN} has been configured with the option @option{--prefix=$prefix},
|
|
it may be subject to relocation. Two possible cases:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
If the default location of this init file contains @file{$prefix},
|
|
it will be subject to relocation. Suppose that the configure options
|
|
are @option{--prefix=$prefix --with-system-gdbinit=$prefix/etc/gdbinit};
|
|
if @value{GDBN} is moved from @file{$prefix} to @file{$install}, the system
|
|
init file is looked for as @file{$install/etc/gdbinit} instead of
|
|
@file{$prefix/etc/gdbinit}.
|
|
|
|
@item
|
|
By contrast, if the default location does not contain the prefix,
|
|
it will not be relocated. E.g.@: if @value{GDBN} has been configured with
|
|
@option{--prefix=/usr/local --with-system-gdbinit=/usr/share/gdb/gdbinit},
|
|
then @value{GDBN} will always look for @file{/usr/share/gdb/gdbinit},
|
|
wherever @value{GDBN} is installed.
|
|
@end itemize
|
|
|
|
@node Maintenance Commands
|
|
@appendix Maintenance Commands
|
|
@cindex maintenance commands
|
|
@cindex internal commands
|
|
|
|
In addition to commands intended for @value{GDBN} users, @value{GDBN}
|
|
includes a number of commands intended for @value{GDBN} developers,
|
|
that are not documented elsewhere in this manual. These commands are
|
|
provided here for reference. (For commands that turn on debugging
|
|
messages, see @ref{Debugging Output}.)
|
|
|
|
@table @code
|
|
@kindex maint agent
|
|
@kindex maint agent-eval
|
|
@item maint agent @r{[}-at @var{location}@r{,}@r{]} @var{expression}
|
|
@itemx maint agent-eval @r{[}-at @var{location}@r{,}@r{]} @var{expression}
|
|
Translate the given @var{expression} into remote agent bytecodes.
|
|
This command is useful for debugging the Agent Expression mechanism
|
|
(@pxref{Agent Expressions}). The @samp{agent} version produces an
|
|
expression useful for data collection, such as by tracepoints, while
|
|
@samp{maint agent-eval} produces an expression that evaluates directly
|
|
to a result. For instance, a collection expression for @code{globa +
|
|
globb} will include bytecodes to record four bytes of memory at each
|
|
of the addresses of @code{globa} and @code{globb}, while discarding
|
|
the result of the addition, while an evaluation expression will do the
|
|
addition and return the sum.
|
|
If @code{-at} is given, generate remote agent bytecode for @var{location}.
|
|
If not, generate remote agent bytecode for current frame PC address.
|
|
|
|
@kindex maint agent-printf
|
|
@item maint agent-printf @var{format},@var{expr},...
|
|
Translate the given format string and list of argument expressions
|
|
into remote agent bytecodes and display them as a disassembled list.
|
|
This command is useful for debugging the agent version of dynamic
|
|
printf (@pxref{Dynamic Printf}.
|
|
|
|
@kindex maint info breakpoints
|
|
@item @anchor{maint info breakpoints}maint info breakpoints
|
|
Using the same format as @samp{info breakpoints}, display both the
|
|
breakpoints you've set explicitly, and those @value{GDBN} is using for
|
|
internal purposes. Internal breakpoints are shown with negative
|
|
breakpoint numbers. The type column identifies what kind of breakpoint
|
|
is shown:
|
|
|
|
@table @code
|
|
@item breakpoint
|
|
Normal, explicitly set breakpoint.
|
|
|
|
@item watchpoint
|
|
Normal, explicitly set watchpoint.
|
|
|
|
@item longjmp
|
|
Internal breakpoint, used to handle correctly stepping through
|
|
@code{longjmp} calls.
|
|
|
|
@item longjmp resume
|
|
Internal breakpoint at the target of a @code{longjmp}.
|
|
|
|
@item until
|
|
Temporary internal breakpoint used by the @value{GDBN} @code{until} command.
|
|
|
|
@item finish
|
|
Temporary internal breakpoint used by the @value{GDBN} @code{finish} command.
|
|
|
|
@item shlib events
|
|
Shared library events.
|
|
|
|
@end table
|
|
|
|
@kindex maint info bfds
|
|
@item maint info bfds
|
|
This prints information about each @code{bfd} object that is known to
|
|
@value{GDBN}. @xref{Top, , BFD, bfd, The Binary File Descriptor Library}.
|
|
|
|
@kindex set displaced-stepping
|
|
@kindex show displaced-stepping
|
|
@cindex displaced stepping support
|
|
@cindex out-of-line single-stepping
|
|
@item set displaced-stepping
|
|
@itemx show displaced-stepping
|
|
Control whether or not @value{GDBN} will do @dfn{displaced stepping}
|
|
if the target supports it. Displaced stepping is a way to single-step
|
|
over breakpoints without removing them from the inferior, by executing
|
|
an out-of-line copy of the instruction that was originally at the
|
|
breakpoint location. It is also known as out-of-line single-stepping.
|
|
|
|
@table @code
|
|
@item set displaced-stepping on
|
|
If the target architecture supports it, @value{GDBN} will use
|
|
displaced stepping to step over breakpoints.
|
|
|
|
@item set displaced-stepping off
|
|
@value{GDBN} will not use displaced stepping to step over breakpoints,
|
|
even if such is supported by the target architecture.
|
|
|
|
@cindex non-stop mode, and @samp{set displaced-stepping}
|
|
@item set displaced-stepping auto
|
|
This is the default mode. @value{GDBN} will use displaced stepping
|
|
only if non-stop mode is active (@pxref{Non-Stop Mode}) and the target
|
|
architecture supports displaced stepping.
|
|
@end table
|
|
|
|
@kindex maint check-symtabs
|
|
@item maint check-symtabs
|
|
Check the consistency of psymtabs and symtabs.
|
|
|
|
@kindex maint cplus first_component
|
|
@item maint cplus first_component @var{name}
|
|
Print the first C@t{++} class/namespace component of @var{name}.
|
|
|
|
@kindex maint cplus namespace
|
|
@item maint cplus namespace
|
|
Print the list of possible C@t{++} namespaces.
|
|
|
|
@kindex maint demangle
|
|
@item maint demangle @var{name}
|
|
Demangle a C@t{++} or Objective-C mangled @var{name}.
|
|
|
|
@kindex maint deprecate
|
|
@kindex maint undeprecate
|
|
@cindex deprecated commands
|
|
@item maint deprecate @var{command} @r{[}@var{replacement}@r{]}
|
|
@itemx maint undeprecate @var{command}
|
|
Deprecate or undeprecate the named @var{command}. Deprecated commands
|
|
cause @value{GDBN} to issue a warning when you use them. The optional
|
|
argument @var{replacement} says which newer command should be used in
|
|
favor of the deprecated one; if it is given, @value{GDBN} will mention
|
|
the replacement as part of the warning.
|
|
|
|
@kindex maint dump-me
|
|
@item maint dump-me
|
|
@cindex @code{SIGQUIT} signal, dump core of @value{GDBN}
|
|
Cause a fatal signal in the debugger and force it to dump its core.
|
|
This is supported only on systems which support aborting a program
|
|
with the @code{SIGQUIT} signal.
|
|
|
|
@kindex maint internal-error
|
|
@kindex maint internal-warning
|
|
@item maint internal-error @r{[}@var{message-text}@r{]}
|
|
@itemx maint internal-warning @r{[}@var{message-text}@r{]}
|
|
Cause @value{GDBN} to call the internal function @code{internal_error}
|
|
or @code{internal_warning} and hence behave as though an internal error
|
|
or internal warning has been detected. In addition to reporting the
|
|
internal problem, these functions give the user the opportunity to
|
|
either quit @value{GDBN} or create a core file of the current
|
|
@value{GDBN} session.
|
|
|
|
These commands take an optional parameter @var{message-text} that is
|
|
used as the text of the error or warning message.
|
|
|
|
Here's an example of using @code{internal-error}:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) @kbd{maint internal-error testing, 1, 2}
|
|
@dots{}/maint.c:121: internal-error: testing, 1, 2
|
|
A problem internal to GDB has been detected. Further
|
|
debugging may prove unreliable.
|
|
Quit this debugging session? (y or n) @kbd{n}
|
|
Create a core file? (y or n) @kbd{n}
|
|
(@value{GDBP})
|
|
@end smallexample
|
|
|
|
@cindex @value{GDBN} internal error
|
|
@cindex internal errors, control of @value{GDBN} behavior
|
|
|
|
@kindex maint set internal-error
|
|
@kindex maint show internal-error
|
|
@kindex maint set internal-warning
|
|
@kindex maint show internal-warning
|
|
@item maint set internal-error @var{action} [ask|yes|no]
|
|
@itemx maint show internal-error @var{action}
|
|
@itemx maint set internal-warning @var{action} [ask|yes|no]
|
|
@itemx maint show internal-warning @var{action}
|
|
When @value{GDBN} reports an internal problem (error or warning) it
|
|
gives the user the opportunity to both quit @value{GDBN} and create a
|
|
core file of the current @value{GDBN} session. These commands let you
|
|
override the default behaviour for each particular @var{action},
|
|
described in the table below.
|
|
|
|
@table @samp
|
|
@item quit
|
|
You can specify that @value{GDBN} should always (yes) or never (no)
|
|
quit. The default is to ask the user what to do.
|
|
|
|
@item corefile
|
|
You can specify that @value{GDBN} should always (yes) or never (no)
|
|
create a core file. The default is to ask the user what to do.
|
|
@end table
|
|
|
|
@kindex maint packet
|
|
@item maint packet @var{text}
|
|
If @value{GDBN} is talking to an inferior via the serial protocol,
|
|
then this command sends the string @var{text} to the inferior, and
|
|
displays the response packet. @value{GDBN} supplies the initial
|
|
@samp{$} character, the terminating @samp{#} character, and the
|
|
checksum.
|
|
|
|
@kindex maint print architecture
|
|
@item maint print architecture @r{[}@var{file}@r{]}
|
|
Print the entire architecture configuration. The optional argument
|
|
@var{file} names the file where the output goes.
|
|
|
|
@kindex maint print c-tdesc
|
|
@item maint print c-tdesc
|
|
Print the current target description (@pxref{Target Descriptions}) as
|
|
a C source file. The created source file can be used in @value{GDBN}
|
|
when an XML parser is not available to parse the description.
|
|
|
|
@kindex maint print dummy-frames
|
|
@item maint print dummy-frames
|
|
Prints the contents of @value{GDBN}'s internal dummy-frame stack.
|
|
|
|
@smallexample
|
|
(@value{GDBP}) @kbd{b add}
|
|
@dots{}
|
|
(@value{GDBP}) @kbd{print add(2,3)}
|
|
Breakpoint 2, add (a=2, b=3) at @dots{}
|
|
58 return (a + b);
|
|
The program being debugged stopped while in a function called from GDB.
|
|
@dots{}
|
|
(@value{GDBP}) @kbd{maint print dummy-frames}
|
|
0x1a57c80: pc=0x01014068 fp=0x0200bddc sp=0x0200bdd6
|
|
top=0x0200bdd4 id=@{stack=0x200bddc,code=0x101405c@}
|
|
call_lo=0x01014000 call_hi=0x01014001
|
|
(@value{GDBP})
|
|
@end smallexample
|
|
|
|
Takes an optional file parameter.
|
|
|
|
@kindex maint print registers
|
|
@kindex maint print raw-registers
|
|
@kindex maint print cooked-registers
|
|
@kindex maint print register-groups
|
|
@kindex maint print remote-registers
|
|
@item maint print registers @r{[}@var{file}@r{]}
|
|
@itemx maint print raw-registers @r{[}@var{file}@r{]}
|
|
@itemx maint print cooked-registers @r{[}@var{file}@r{]}
|
|
@itemx maint print register-groups @r{[}@var{file}@r{]}
|
|
@itemx maint print remote-registers @r{[}@var{file}@r{]}
|
|
Print @value{GDBN}'s internal register data structures.
|
|
|
|
The command @code{maint print raw-registers} includes the contents of
|
|
the raw register cache; the command @code{maint print
|
|
cooked-registers} includes the (cooked) value of all registers,
|
|
including registers which aren't available on the target nor visible
|
|
to user; the command @code{maint print register-groups} includes the
|
|
groups that each register is a member of; and the command @code{maint
|
|
print remote-registers} includes the remote target's register numbers
|
|
and offsets in the `G' packets. @xref{Registers,, Registers, gdbint,
|
|
@value{GDBN} Internals}.
|
|
|
|
These commands take an optional parameter, a file name to which to
|
|
write the information.
|
|
|
|
@kindex maint print reggroups
|
|
@item maint print reggroups @r{[}@var{file}@r{]}
|
|
Print @value{GDBN}'s internal register group data structures. The
|
|
optional argument @var{file} tells to what file to write the
|
|
information.
|
|
|
|
The register groups info looks like this:
|
|
|
|
@smallexample
|
|
(@value{GDBP}) @kbd{maint print reggroups}
|
|
Group Type
|
|
general user
|
|
float user
|
|
all user
|
|
vector user
|
|
system user
|
|
save internal
|
|
restore internal
|
|
@end smallexample
|
|
|
|
@kindex flushregs
|
|
@item flushregs
|
|
This command forces @value{GDBN} to flush its internal register cache.
|
|
|
|
@kindex maint print objfiles
|
|
@cindex info for known object files
|
|
@item maint print objfiles
|
|
Print a dump of all known object files. For each object file, this
|
|
command prints its name, address in memory, and all of its psymtabs
|
|
and symtabs.
|
|
|
|
@kindex maint print section-scripts
|
|
@cindex info for known .debug_gdb_scripts-loaded scripts
|
|
@item maint print section-scripts [@var{regexp}]
|
|
Print a dump of scripts specified in the @code{.debug_gdb_section} section.
|
|
If @var{regexp} is specified, only print scripts loaded by object files
|
|
matching @var{regexp}.
|
|
For each script, this command prints its name as specified in the objfile,
|
|
and the full path if known.
|
|
@xref{dotdebug_gdb_scripts section}.
|
|
|
|
@kindex maint print statistics
|
|
@cindex bcache statistics
|
|
@item maint print statistics
|
|
This command prints, for each object file in the program, various data
|
|
about that object file followed by the byte cache (@dfn{bcache})
|
|
statistics for the object file. The objfile data includes the number
|
|
of minimal, partial, full, and stabs symbols, the number of types
|
|
defined by the objfile, the number of as yet unexpanded psym tables,
|
|
the number of line tables and string tables, and the amount of memory
|
|
used by the various tables. The bcache statistics include the counts,
|
|
sizes, and counts of duplicates of all and unique objects, max,
|
|
average, and median entry size, total memory used and its overhead and
|
|
savings, and various measures of the hash table size and chain
|
|
lengths.
|
|
|
|
@kindex maint print target-stack
|
|
@cindex target stack description
|
|
@item maint print target-stack
|
|
A @dfn{target} is an interface between the debugger and a particular
|
|
kind of file or process. Targets can be stacked in @dfn{strata},
|
|
so that more than one target can potentially respond to a request.
|
|
In particular, memory accesses will walk down the stack of targets
|
|
until they find a target that is interested in handling that particular
|
|
address.
|
|
|
|
This command prints a short description of each layer that was pushed on
|
|
the @dfn{target stack}, starting from the top layer down to the bottom one.
|
|
|
|
@kindex maint print type
|
|
@cindex type chain of a data type
|
|
@item maint print type @var{expr}
|
|
Print the type chain for a type specified by @var{expr}. The argument
|
|
can be either a type name or a symbol. If it is a symbol, the type of
|
|
that symbol is described. The type chain produced by this command is
|
|
a recursive definition of the data type as stored in @value{GDBN}'s
|
|
data structures, including its flags and contained types.
|
|
|
|
@kindex maint set dwarf2 always-disassemble
|
|
@kindex maint show dwarf2 always-disassemble
|
|
@item maint set dwarf2 always-disassemble
|
|
@item maint show dwarf2 always-disassemble
|
|
Control the behavior of @code{info address} when using DWARF debugging
|
|
information.
|
|
|
|
The default is @code{off}, which means that @value{GDBN} should try to
|
|
describe a variable's location in an easily readable format. When
|
|
@code{on}, @value{GDBN} will instead display the DWARF location
|
|
expression in an assembly-like format. Note that some locations are
|
|
too complex for @value{GDBN} to describe simply; in this case you will
|
|
always see the disassembly form.
|
|
|
|
Here is an example of the resulting disassembly:
|
|
|
|
@smallexample
|
|
(gdb) info addr argc
|
|
Symbol "argc" is a complex DWARF expression:
|
|
1: DW_OP_fbreg 0
|
|
@end smallexample
|
|
|
|
For more information on these expressions, see
|
|
@uref{http://www.dwarfstd.org/, the DWARF standard}.
|
|
|
|
@kindex maint set dwarf2 max-cache-age
|
|
@kindex maint show dwarf2 max-cache-age
|
|
@item maint set dwarf2 max-cache-age
|
|
@itemx maint show dwarf2 max-cache-age
|
|
Control the DWARF 2 compilation unit cache.
|
|
|
|
@cindex DWARF 2 compilation units cache
|
|
In object files with inter-compilation-unit references, such as those
|
|
produced by the GCC option @samp{-feliminate-dwarf2-dups}, the DWARF 2
|
|
reader needs to frequently refer to previously read compilation units.
|
|
This setting controls how long a compilation unit will remain in the
|
|
cache if it is not referenced. A higher limit means that cached
|
|
compilation units will be stored in memory longer, and more total
|
|
memory will be used. Setting it to zero disables caching, which will
|
|
slow down @value{GDBN} startup, but reduce memory consumption.
|
|
|
|
@kindex maint set profile
|
|
@kindex maint show profile
|
|
@cindex profiling GDB
|
|
@item maint set profile
|
|
@itemx maint show profile
|
|
Control profiling of @value{GDBN}.
|
|
|
|
Profiling will be disabled until you use the @samp{maint set profile}
|
|
command to enable it. When you enable profiling, the system will begin
|
|
collecting timing and execution count data; when you disable profiling or
|
|
exit @value{GDBN}, the results will be written to a log file. Remember that
|
|
if you use profiling, @value{GDBN} will overwrite the profiling log file
|
|
(often called @file{gmon.out}). If you have a record of important profiling
|
|
data in a @file{gmon.out} file, be sure to move it to a safe location.
|
|
|
|
Configuring with @samp{--enable-profiling} arranges for @value{GDBN} to be
|
|
compiled with the @samp{-pg} compiler option.
|
|
|
|
@kindex maint set show-debug-regs
|
|
@kindex maint show show-debug-regs
|
|
@cindex hardware debug registers
|
|
@item maint set show-debug-regs
|
|
@itemx maint show show-debug-regs
|
|
Control whether to show variables that mirror the hardware debug
|
|
registers. Use @code{ON} to enable, @code{OFF} to disable. If
|
|
enabled, the debug registers values are shown when @value{GDBN} inserts or
|
|
removes a hardware breakpoint or watchpoint, and when the inferior
|
|
triggers a hardware-assisted breakpoint or watchpoint.
|
|
|
|
@kindex maint set show-all-tib
|
|
@kindex maint show show-all-tib
|
|
@item maint set show-all-tib
|
|
@itemx maint show show-all-tib
|
|
Control whether to show all non zero areas within a 1k block starting
|
|
at thread local base, when using the @samp{info w32 thread-information-block}
|
|
command.
|
|
|
|
@kindex maint space
|
|
@cindex memory used by commands
|
|
@item maint space
|
|
Control whether to display memory usage for each command. If set to a
|
|
nonzero value, @value{GDBN} will display how much memory each command
|
|
took, following the command's own output. This can also be requested
|
|
by invoking @value{GDBN} with the @option{--statistics} command-line
|
|
switch (@pxref{Mode Options}).
|
|
|
|
@kindex maint time
|
|
@cindex time of command execution
|
|
@item maint time
|
|
Control whether to display the execution time of @value{GDBN} for each command.
|
|
If set to a nonzero value, @value{GDBN} will display how much time it
|
|
took to execute each command, following the command's own output.
|
|
Both CPU time and wallclock time are printed.
|
|
Printing both is useful when trying to determine whether the cost is
|
|
CPU or, e.g., disk/network, latency.
|
|
Note that the CPU time printed is for @value{GDBN} only, it does not include
|
|
the execution time of the inferior because there's no mechanism currently
|
|
to compute how much time was spent by @value{GDBN} and how much time was
|
|
spent by the program been debugged.
|
|
This can also be requested by invoking @value{GDBN} with the
|
|
@option{--statistics} command-line switch (@pxref{Mode Options}).
|
|
|
|
@kindex maint translate-address
|
|
@item maint translate-address @r{[}@var{section}@r{]} @var{addr}
|
|
Find the symbol stored at the location specified by the address
|
|
@var{addr} and an optional section name @var{section}. If found,
|
|
@value{GDBN} prints the name of the closest symbol and an offset from
|
|
the symbol's location to the specified address. This is similar to
|
|
the @code{info address} command (@pxref{Symbols}), except that this
|
|
command also allows to find symbols in other sections.
|
|
|
|
If section was not specified, the section in which the symbol was found
|
|
is also printed. For dynamically linked executables, the name of
|
|
executable or shared library containing the symbol is printed as well.
|
|
|
|
@end table
|
|
|
|
The following command is useful for non-interactive invocations of
|
|
@value{GDBN}, such as in the test suite.
|
|
|
|
@table @code
|
|
@item set watchdog @var{nsec}
|
|
@kindex set watchdog
|
|
@cindex watchdog timer
|
|
@cindex timeout for commands
|
|
Set the maximum number of seconds @value{GDBN} will wait for the
|
|
target operation to finish. If this time expires, @value{GDBN}
|
|
reports and error and the command is aborted.
|
|
|
|
@item show watchdog
|
|
Show the current setting of the target wait timeout.
|
|
@end table
|
|
|
|
@node Remote Protocol
|
|
@appendix @value{GDBN} Remote Serial Protocol
|
|
|
|
@menu
|
|
* Overview::
|
|
* Packets::
|
|
* Stop Reply Packets::
|
|
* General Query Packets::
|
|
* Architecture-Specific Protocol Details::
|
|
* Tracepoint Packets::
|
|
* Host I/O Packets::
|
|
* Interrupts::
|
|
* Notification Packets::
|
|
* Remote Non-Stop::
|
|
* Packet Acknowledgment::
|
|
* Examples::
|
|
* File-I/O Remote Protocol Extension::
|
|
* Library List Format::
|
|
* Library List Format for SVR4 Targets::
|
|
* Memory Map Format::
|
|
* Thread List Format::
|
|
* Traceframe Info Format::
|
|
@end menu
|
|
|
|
@node Overview
|
|
@section Overview
|
|
|
|
There may be occasions when you need to know something about the
|
|
protocol---for example, if there is only one serial port to your target
|
|
machine, you might want your program to do something special if it
|
|
recognizes a packet meant for @value{GDBN}.
|
|
|
|
In the examples below, @samp{->} and @samp{<-} are used to indicate
|
|
transmitted and received data, respectively.
|
|
|
|
@cindex protocol, @value{GDBN} remote serial
|
|
@cindex serial protocol, @value{GDBN} remote
|
|
@cindex remote serial protocol
|
|
All @value{GDBN} commands and responses (other than acknowledgments
|
|
and notifications, see @ref{Notification Packets}) are sent as a
|
|
@var{packet}. A @var{packet} is introduced with the character
|
|
@samp{$}, the actual @var{packet-data}, and the terminating character
|
|
@samp{#} followed by a two-digit @var{checksum}:
|
|
|
|
@smallexample
|
|
@code{$}@var{packet-data}@code{#}@var{checksum}
|
|
@end smallexample
|
|
@noindent
|
|
|
|
@cindex checksum, for @value{GDBN} remote
|
|
@noindent
|
|
The two-digit @var{checksum} is computed as the modulo 256 sum of all
|
|
characters between the leading @samp{$} and the trailing @samp{#} (an
|
|
eight bit unsigned checksum).
|
|
|
|
Implementors should note that prior to @value{GDBN} 5.0 the protocol
|
|
specification also included an optional two-digit @var{sequence-id}:
|
|
|
|
@smallexample
|
|
@code{$}@var{sequence-id}@code{:}@var{packet-data}@code{#}@var{checksum}
|
|
@end smallexample
|
|
|
|
@cindex sequence-id, for @value{GDBN} remote
|
|
@noindent
|
|
That @var{sequence-id} was appended to the acknowledgment. @value{GDBN}
|
|
has never output @var{sequence-id}s. Stubs that handle packets added
|
|
since @value{GDBN} 5.0 must not accept @var{sequence-id}.
|
|
|
|
When either the host or the target machine receives a packet, the first
|
|
response expected is an acknowledgment: either @samp{+} (to indicate
|
|
the package was received correctly) or @samp{-} (to request
|
|
retransmission):
|
|
|
|
@smallexample
|
|
-> @code{$}@var{packet-data}@code{#}@var{checksum}
|
|
<- @code{+}
|
|
@end smallexample
|
|
@noindent
|
|
|
|
The @samp{+}/@samp{-} acknowledgments can be disabled
|
|
once a connection is established.
|
|
@xref{Packet Acknowledgment}, for details.
|
|
|
|
The host (@value{GDBN}) sends @var{command}s, and the target (the
|
|
debugging stub incorporated in your program) sends a @var{response}. In
|
|
the case of step and continue @var{command}s, the response is only sent
|
|
when the operation has completed, and the target has again stopped all
|
|
threads in all attached processes. This is the default all-stop mode
|
|
behavior, but the remote protocol also supports @value{GDBN}'s non-stop
|
|
execution mode; see @ref{Remote Non-Stop}, for details.
|
|
|
|
@var{packet-data} consists of a sequence of characters with the
|
|
exception of @samp{#} and @samp{$} (see @samp{X} packet for additional
|
|
exceptions).
|
|
|
|
@cindex remote protocol, field separator
|
|
Fields within the packet should be separated using @samp{,} @samp{;} or
|
|
@samp{:}. Except where otherwise noted all numbers are represented in
|
|
@sc{hex} with leading zeros suppressed.
|
|
|
|
Implementors should note that prior to @value{GDBN} 5.0, the character
|
|
@samp{:} could not appear as the third character in a packet (as it
|
|
would potentially conflict with the @var{sequence-id}).
|
|
|
|
@cindex remote protocol, binary data
|
|
@anchor{Binary Data}
|
|
Binary data in most packets is encoded either as two hexadecimal
|
|
digits per byte of binary data. This allowed the traditional remote
|
|
protocol to work over connections which were only seven-bit clean.
|
|
Some packets designed more recently assume an eight-bit clean
|
|
connection, and use a more efficient encoding to send and receive
|
|
binary data.
|
|
|
|
The binary data representation uses @code{7d} (@sc{ascii} @samp{@}})
|
|
as an escape character. Any escaped byte is transmitted as the escape
|
|
character followed by the original character XORed with @code{0x20}.
|
|
For example, the byte @code{0x7d} would be transmitted as the two
|
|
bytes @code{0x7d 0x5d}. The bytes @code{0x23} (@sc{ascii} @samp{#}),
|
|
@code{0x24} (@sc{ascii} @samp{$}), and @code{0x7d} (@sc{ascii}
|
|
@samp{@}}) must always be escaped. Responses sent by the stub
|
|
must also escape @code{0x2a} (@sc{ascii} @samp{*}), so that it
|
|
is not interpreted as the start of a run-length encoded sequence
|
|
(described next).
|
|
|
|
Response @var{data} can be run-length encoded to save space.
|
|
Run-length encoding replaces runs of identical characters with one
|
|
instance of the repeated character, followed by a @samp{*} and a
|
|
repeat count. The repeat count is itself sent encoded, to avoid
|
|
binary characters in @var{data}: a value of @var{n} is sent as
|
|
@code{@var{n}+29}. For a repeat count greater or equal to 3, this
|
|
produces a printable @sc{ascii} character, e.g.@: a space (@sc{ascii}
|
|
code 32) for a repeat count of 3. (This is because run-length
|
|
encoding starts to win for counts 3 or more.) Thus, for example,
|
|
@samp{0* } is a run-length encoding of ``0000'': the space character
|
|
after @samp{*} means repeat the leading @code{0} @w{@code{32 - 29 =
|
|
3}} more times.
|
|
|
|
The printable characters @samp{#} and @samp{$} or with a numeric value
|
|
greater than 126 must not be used. Runs of six repeats (@samp{#}) or
|
|
seven repeats (@samp{$}) can be expanded using a repeat count of only
|
|
five (@samp{"}). For example, @samp{00000000} can be encoded as
|
|
@samp{0*"00}.
|
|
|
|
The error response returned for some packets includes a two character
|
|
error number. That number is not well defined.
|
|
|
|
@cindex empty response, for unsupported packets
|
|
For any @var{command} not supported by the stub, an empty response
|
|
(@samp{$#00}) should be returned. That way it is possible to extend the
|
|
protocol. A newer @value{GDBN} can tell if a packet is supported based
|
|
on that response.
|
|
|
|
At a minimum, a stub is required to support the @samp{g} and @samp{G}
|
|
commands for register access, and the @samp{m} and @samp{M} commands
|
|
for memory access. Stubs that only control single-threaded targets
|
|
can implement run control with the @samp{c} (continue), and @samp{s}
|
|
(step) commands. Stubs that support multi-threading targets should
|
|
support the @samp{vCont} command. All other commands are optional.
|
|
|
|
@node Packets
|
|
@section Packets
|
|
|
|
The following table provides a complete list of all currently defined
|
|
@var{command}s and their corresponding response @var{data}.
|
|
@xref{File-I/O Remote Protocol Extension}, for details about the File
|
|
I/O extension of the remote protocol.
|
|
|
|
Each packet's description has a template showing the packet's overall
|
|
syntax, followed by an explanation of the packet's meaning. We
|
|
include spaces in some of the templates for clarity; these are not
|
|
part of the packet's syntax. No @value{GDBN} packet uses spaces to
|
|
separate its components. For example, a template like @samp{foo
|
|
@var{bar} @var{baz}} describes a packet beginning with the three ASCII
|
|
bytes @samp{foo}, followed by a @var{bar}, followed directly by a
|
|
@var{baz}. @value{GDBN} does not transmit a space character between the
|
|
@samp{foo} and the @var{bar}, or between the @var{bar} and the
|
|
@var{baz}.
|
|
|
|
@cindex @var{thread-id}, in remote protocol
|
|
@anchor{thread-id syntax}
|
|
Several packets and replies include a @var{thread-id} field to identify
|
|
a thread. Normally these are positive numbers with a target-specific
|
|
interpretation, formatted as big-endian hex strings. A @var{thread-id}
|
|
can also be a literal @samp{-1} to indicate all threads, or @samp{0} to
|
|
pick any thread.
|
|
|
|
In addition, the remote protocol supports a multiprocess feature in
|
|
which the @var{thread-id} syntax is extended to optionally include both
|
|
process and thread ID fields, as @samp{p@var{pid}.@var{tid}}.
|
|
The @var{pid} (process) and @var{tid} (thread) components each have the
|
|
format described above: a positive number with target-specific
|
|
interpretation formatted as a big-endian hex string, literal @samp{-1}
|
|
to indicate all processes or threads (respectively), or @samp{0} to
|
|
indicate an arbitrary process or thread. Specifying just a process, as
|
|
@samp{p@var{pid}}, is equivalent to @samp{p@var{pid}.-1}. It is an
|
|
error to specify all processes but a specific thread, such as
|
|
@samp{p-1.@var{tid}}. Note that the @samp{p} prefix is @emph{not} used
|
|
for those packets and replies explicitly documented to include a process
|
|
ID, rather than a @var{thread-id}.
|
|
|
|
The multiprocess @var{thread-id} syntax extensions are only used if both
|
|
@value{GDBN} and the stub report support for the @samp{multiprocess}
|
|
feature using @samp{qSupported}. @xref{multiprocess extensions}, for
|
|
more information.
|
|
|
|
Note that all packet forms beginning with an upper- or lower-case
|
|
letter, other than those described here, are reserved for future use.
|
|
|
|
Here are the packet descriptions.
|
|
|
|
@table @samp
|
|
|
|
@item !
|
|
@cindex @samp{!} packet
|
|
@anchor{extended mode}
|
|
Enable extended mode. In extended mode, the remote server is made
|
|
persistent. The @samp{R} packet is used to restart the program being
|
|
debugged.
|
|
|
|
Reply:
|
|
@table @samp
|
|
@item OK
|
|
The remote target both supports and has enabled extended mode.
|
|
@end table
|
|
|
|
@item ?
|
|
@cindex @samp{?} packet
|
|
Indicate the reason the target halted. The reply is the same as for
|
|
step and continue. This packet has a special interpretation when the
|
|
target is in non-stop mode; see @ref{Remote Non-Stop}.
|
|
|
|
Reply:
|
|
@xref{Stop Reply Packets}, for the reply specifications.
|
|
|
|
@item A @var{arglen},@var{argnum},@var{arg},@dots{}
|
|
@cindex @samp{A} packet
|
|
Initialized @code{argv[]} array passed into program. @var{arglen}
|
|
specifies the number of bytes in the hex encoded byte stream
|
|
@var{arg}. See @code{gdbserver} for more details.
|
|
|
|
Reply:
|
|
@table @samp
|
|
@item OK
|
|
The arguments were set.
|
|
@item E @var{NN}
|
|
An error occurred.
|
|
@end table
|
|
|
|
@item b @var{baud}
|
|
@cindex @samp{b} packet
|
|
(Don't use this packet; its behavior is not well-defined.)
|
|
Change the serial line speed to @var{baud}.
|
|
|
|
JTC: @emph{When does the transport layer state change? When it's
|
|
received, or after the ACK is transmitted. In either case, there are
|
|
problems if the command or the acknowledgment packet is dropped.}
|
|
|
|
Stan: @emph{If people really wanted to add something like this, and get
|
|
it working for the first time, they ought to modify ser-unix.c to send
|
|
some kind of out-of-band message to a specially-setup stub and have the
|
|
switch happen "in between" packets, so that from remote protocol's point
|
|
of view, nothing actually happened.}
|
|
|
|
@item B @var{addr},@var{mode}
|
|
@cindex @samp{B} packet
|
|
Set (@var{mode} is @samp{S}) or clear (@var{mode} is @samp{C}) a
|
|
breakpoint at @var{addr}.
|
|
|
|
Don't use this packet. Use the @samp{Z} and @samp{z} packets instead
|
|
(@pxref{insert breakpoint or watchpoint packet}).
|
|
|
|
@cindex @samp{bc} packet
|
|
@anchor{bc}
|
|
@item bc
|
|
Backward continue. Execute the target system in reverse. No parameter.
|
|
@xref{Reverse Execution}, for more information.
|
|
|
|
Reply:
|
|
@xref{Stop Reply Packets}, for the reply specifications.
|
|
|
|
@cindex @samp{bs} packet
|
|
@anchor{bs}
|
|
@item bs
|
|
Backward single step. Execute one instruction in reverse. No parameter.
|
|
@xref{Reverse Execution}, for more information.
|
|
|
|
Reply:
|
|
@xref{Stop Reply Packets}, for the reply specifications.
|
|
|
|
@item c @r{[}@var{addr}@r{]}
|
|
@cindex @samp{c} packet
|
|
Continue. @var{addr} is address to resume. If @var{addr} is omitted,
|
|
resume at current address.
|
|
|
|
This packet is deprecated for multi-threading support. @xref{vCont
|
|
packet}.
|
|
|
|
Reply:
|
|
@xref{Stop Reply Packets}, for the reply specifications.
|
|
|
|
@item C @var{sig}@r{[};@var{addr}@r{]}
|
|
@cindex @samp{C} packet
|
|
Continue with signal @var{sig} (hex signal number). If
|
|
@samp{;@var{addr}} is omitted, resume at same address.
|
|
|
|
This packet is deprecated for multi-threading support. @xref{vCont
|
|
packet}.
|
|
|
|
Reply:
|
|
@xref{Stop Reply Packets}, for the reply specifications.
|
|
|
|
@item d
|
|
@cindex @samp{d} packet
|
|
Toggle debug flag.
|
|
|
|
Don't use this packet; instead, define a general set packet
|
|
(@pxref{General Query Packets}).
|
|
|
|
@item D
|
|
@itemx D;@var{pid}
|
|
@cindex @samp{D} packet
|
|
The first form of the packet is used to detach @value{GDBN} from the
|
|
remote system. It is sent to the remote target
|
|
before @value{GDBN} disconnects via the @code{detach} command.
|
|
|
|
The second form, including a process ID, is used when multiprocess
|
|
protocol extensions are enabled (@pxref{multiprocess extensions}), to
|
|
detach only a specific process. The @var{pid} is specified as a
|
|
big-endian hex string.
|
|
|
|
Reply:
|
|
@table @samp
|
|
@item OK
|
|
for success
|
|
@item E @var{NN}
|
|
for an error
|
|
@end table
|
|
|
|
@item F @var{RC},@var{EE},@var{CF};@var{XX}
|
|
@cindex @samp{F} packet
|
|
A reply from @value{GDBN} to an @samp{F} packet sent by the target.
|
|
This is part of the File-I/O protocol extension. @xref{File-I/O
|
|
Remote Protocol Extension}, for the specification.
|
|
|
|
@item g
|
|
@anchor{read registers packet}
|
|
@cindex @samp{g} packet
|
|
Read general registers.
|
|
|
|
Reply:
|
|
@table @samp
|
|
@item @var{XX@dots{}}
|
|
Each byte of register data is described by two hex digits. The bytes
|
|
with the register are transmitted in target byte order. The size of
|
|
each register and their position within the @samp{g} packet are
|
|
determined by the @value{GDBN} internal gdbarch functions
|
|
@code{DEPRECATED_REGISTER_RAW_SIZE} and @code{gdbarch_register_name}. The
|
|
specification of several standard @samp{g} packets is specified below.
|
|
|
|
When reading registers from a trace frame (@pxref{Analyze Collected
|
|
Data,,Using the Collected Data}), the stub may also return a string of
|
|
literal @samp{x}'s in place of the register data digits, to indicate
|
|
that the corresponding register has not been collected, thus its value
|
|
is unavailable. For example, for an architecture with 4 registers of
|
|
4 bytes each, the following reply indicates to @value{GDBN} that
|
|
registers 0 and 2 have not been collected, while registers 1 and 3
|
|
have been collected, and both have zero value:
|
|
|
|
@smallexample
|
|
-> @code{g}
|
|
<- @code{xxxxxxxx00000000xxxxxxxx00000000}
|
|
@end smallexample
|
|
|
|
@item E @var{NN}
|
|
for an error.
|
|
@end table
|
|
|
|
@item G @var{XX@dots{}}
|
|
@cindex @samp{G} packet
|
|
Write general registers. @xref{read registers packet}, for a
|
|
description of the @var{XX@dots{}} data.
|
|
|
|
Reply:
|
|
@table @samp
|
|
@item OK
|
|
for success
|
|
@item E @var{NN}
|
|
for an error
|
|
@end table
|
|
|
|
@item H @var{op} @var{thread-id}
|
|
@cindex @samp{H} packet
|
|
Set thread for subsequent operations (@samp{m}, @samp{M}, @samp{g},
|
|
@samp{G}, et.al.). @var{op} depends on the operation to be performed:
|
|
it should be @samp{c} for step and continue operations (note that this
|
|
is deprecated, supporting the @samp{vCont} command is a better
|
|
option), @samp{g} for other operations. The thread designator
|
|
@var{thread-id} has the format and interpretation described in
|
|
@ref{thread-id syntax}.
|
|
|
|
Reply:
|
|
@table @samp
|
|
@item OK
|
|
for success
|
|
@item E @var{NN}
|
|
for an error
|
|
@end table
|
|
|
|
@c FIXME: JTC:
|
|
@c 'H': How restrictive (or permissive) is the thread model. If a
|
|
@c thread is selected and stopped, are other threads allowed
|
|
@c to continue to execute? As I mentioned above, I think the
|
|
@c semantics of each command when a thread is selected must be
|
|
@c described. For example:
|
|
@c
|
|
@c 'g': If the stub supports threads and a specific thread is
|
|
@c selected, returns the register block from that thread;
|
|
@c otherwise returns current registers.
|
|
@c
|
|
@c 'G' If the stub supports threads and a specific thread is
|
|
@c selected, sets the registers of the register block of
|
|
@c that thread; otherwise sets current registers.
|
|
|
|
@item i @r{[}@var{addr}@r{[},@var{nnn}@r{]]}
|
|
@anchor{cycle step packet}
|
|
@cindex @samp{i} packet
|
|
Step the remote target by a single clock cycle. If @samp{,@var{nnn}} is
|
|
present, cycle step @var{nnn} cycles. If @var{addr} is present, cycle
|
|
step starting at that address.
|
|
|
|
@item I
|
|
@cindex @samp{I} packet
|
|
Signal, then cycle step. @xref{step with signal packet}. @xref{cycle
|
|
step packet}.
|
|
|
|
@item k
|
|
@cindex @samp{k} packet
|
|
Kill request.
|
|
|
|
FIXME: @emph{There is no description of how to operate when a specific
|
|
thread context has been selected (i.e.@: does 'k' kill only that
|
|
thread?)}.
|
|
|
|
@item m @var{addr},@var{length}
|
|
@cindex @samp{m} packet
|
|
Read @var{length} bytes of memory starting at address @var{addr}.
|
|
Note that @var{addr} may not be aligned to any particular boundary.
|
|
|
|
The stub need not use any particular size or alignment when gathering
|
|
data from memory for the response; even if @var{addr} is word-aligned
|
|
and @var{length} is a multiple of the word size, the stub is free to
|
|
use byte accesses, or not. For this reason, this packet may not be
|
|
suitable for accessing memory-mapped I/O devices.
|
|
@cindex alignment of remote memory accesses
|
|
@cindex size of remote memory accesses
|
|
@cindex memory, alignment and size of remote accesses
|
|
|
|
Reply:
|
|
@table @samp
|
|
@item @var{XX@dots{}}
|
|
Memory contents; each byte is transmitted as a two-digit hexadecimal
|
|
number. The reply may contain fewer bytes than requested if the
|
|
server was able to read only part of the region of memory.
|
|
@item E @var{NN}
|
|
@var{NN} is errno
|
|
@end table
|
|
|
|
@item M @var{addr},@var{length}:@var{XX@dots{}}
|
|
@cindex @samp{M} packet
|
|
Write @var{length} bytes of memory starting at address @var{addr}.
|
|
@var{XX@dots{}} is the data; each byte is transmitted as a two-digit
|
|
hexadecimal number.
|
|
|
|
Reply:
|
|
@table @samp
|
|
@item OK
|
|
for success
|
|
@item E @var{NN}
|
|
for an error (this includes the case where only part of the data was
|
|
written).
|
|
@end table
|
|
|
|
@item p @var{n}
|
|
@cindex @samp{p} packet
|
|
Read the value of register @var{n}; @var{n} is in hex.
|
|
@xref{read registers packet}, for a description of how the returned
|
|
register value is encoded.
|
|
|
|
Reply:
|
|
@table @samp
|
|
@item @var{XX@dots{}}
|
|
the register's value
|
|
@item E @var{NN}
|
|
for an error
|
|
@item
|
|
Indicating an unrecognized @var{query}.
|
|
@end table
|
|
|
|
@item P @var{n@dots{}}=@var{r@dots{}}
|
|
@anchor{write register packet}
|
|
@cindex @samp{P} packet
|
|
Write register @var{n@dots{}} with value @var{r@dots{}}. The register
|
|
number @var{n} is in hexadecimal, and @var{r@dots{}} contains two hex
|
|
digits for each byte in the register (target byte order).
|
|
|
|
Reply:
|
|
@table @samp
|
|
@item OK
|
|
for success
|
|
@item E @var{NN}
|
|
for an error
|
|
@end table
|
|
|
|
@item q @var{name} @var{params}@dots{}
|
|
@itemx Q @var{name} @var{params}@dots{}
|
|
@cindex @samp{q} packet
|
|
@cindex @samp{Q} packet
|
|
General query (@samp{q}) and set (@samp{Q}). These packets are
|
|
described fully in @ref{General Query Packets}.
|
|
|
|
@item r
|
|
@cindex @samp{r} packet
|
|
Reset the entire system.
|
|
|
|
Don't use this packet; use the @samp{R} packet instead.
|
|
|
|
@item R @var{XX}
|
|
@cindex @samp{R} packet
|
|
Restart the program being debugged. @var{XX}, while needed, is ignored.
|
|
This packet is only available in extended mode (@pxref{extended mode}).
|
|
|
|
The @samp{R} packet has no reply.
|
|
|
|
@item s @r{[}@var{addr}@r{]}
|
|
@cindex @samp{s} packet
|
|
Single step. @var{addr} is the address at which to resume. If
|
|
@var{addr} is omitted, resume at same address.
|
|
|
|
This packet is deprecated for multi-threading support. @xref{vCont
|
|
packet}.
|
|
|
|
Reply:
|
|
@xref{Stop Reply Packets}, for the reply specifications.
|
|
|
|
@item S @var{sig}@r{[};@var{addr}@r{]}
|
|
@anchor{step with signal packet}
|
|
@cindex @samp{S} packet
|
|
Step with signal. This is analogous to the @samp{C} packet, but
|
|
requests a single-step, rather than a normal resumption of execution.
|
|
|
|
This packet is deprecated for multi-threading support. @xref{vCont
|
|
packet}.
|
|
|
|
Reply:
|
|
@xref{Stop Reply Packets}, for the reply specifications.
|
|
|
|
@item t @var{addr}:@var{PP},@var{MM}
|
|
@cindex @samp{t} packet
|
|
Search backwards starting at address @var{addr} for a match with pattern
|
|
@var{PP} and mask @var{MM}. @var{PP} and @var{MM} are 4 bytes.
|
|
@var{addr} must be at least 3 digits.
|
|
|
|
@item T @var{thread-id}
|
|
@cindex @samp{T} packet
|
|
Find out if the thread @var{thread-id} is alive. @xref{thread-id syntax}.
|
|
|
|
Reply:
|
|
@table @samp
|
|
@item OK
|
|
thread is still alive
|
|
@item E @var{NN}
|
|
thread is dead
|
|
@end table
|
|
|
|
@item v
|
|
Packets starting with @samp{v} are identified by a multi-letter name,
|
|
up to the first @samp{;} or @samp{?} (or the end of the packet).
|
|
|
|
@item vAttach;@var{pid}
|
|
@cindex @samp{vAttach} packet
|
|
Attach to a new process with the specified process ID @var{pid}.
|
|
The process ID is a
|
|
hexadecimal integer identifying the process. In all-stop mode, all
|
|
threads in the attached process are stopped; in non-stop mode, it may be
|
|
attached without being stopped if that is supported by the target.
|
|
|
|
@c In non-stop mode, on a successful vAttach, the stub should set the
|
|
@c current thread to a thread of the newly-attached process. After
|
|
@c attaching, GDB queries for the attached process's thread ID with qC.
|
|
@c Also note that, from a user perspective, whether or not the
|
|
@c target is stopped on attach in non-stop mode depends on whether you
|
|
@c use the foreground or background version of the attach command, not
|
|
@c on what vAttach does; GDB does the right thing with respect to either
|
|
@c stopping or restarting threads.
|
|
|
|
This packet is only available in extended mode (@pxref{extended mode}).
|
|
|
|
Reply:
|
|
@table @samp
|
|
@item E @var{nn}
|
|
for an error
|
|
@item @r{Any stop packet}
|
|
for success in all-stop mode (@pxref{Stop Reply Packets})
|
|
@item OK
|
|
for success in non-stop mode (@pxref{Remote Non-Stop})
|
|
@end table
|
|
|
|
@item vCont@r{[};@var{action}@r{[}:@var{thread-id}@r{]]}@dots{}
|
|
@cindex @samp{vCont} packet
|
|
@anchor{vCont packet}
|
|
Resume the inferior, specifying different actions for each thread.
|
|
If an action is specified with no @var{thread-id}, then it is applied to any
|
|
threads that don't have a specific action specified; if no default action is
|
|
specified then other threads should remain stopped in all-stop mode and
|
|
in their current state in non-stop mode.
|
|
Specifying multiple
|
|
default actions is an error; specifying no actions is also an error.
|
|
Thread IDs are specified using the syntax described in @ref{thread-id syntax}.
|
|
|
|
Currently supported actions are:
|
|
|
|
@table @samp
|
|
@item c
|
|
Continue.
|
|
@item C @var{sig}
|
|
Continue with signal @var{sig}. The signal @var{sig} should be two hex digits.
|
|
@item s
|
|
Step.
|
|
@item S @var{sig}
|
|
Step with signal @var{sig}. The signal @var{sig} should be two hex digits.
|
|
@item t
|
|
Stop.
|
|
@end table
|
|
|
|
The optional argument @var{addr} normally associated with the
|
|
@samp{c}, @samp{C}, @samp{s}, and @samp{S} packets is
|
|
not supported in @samp{vCont}.
|
|
|
|
The @samp{t} action is only relevant in non-stop mode
|
|
(@pxref{Remote Non-Stop}) and may be ignored by the stub otherwise.
|
|
A stop reply should be generated for any affected thread not already stopped.
|
|
When a thread is stopped by means of a @samp{t} action,
|
|
the corresponding stop reply should indicate that the thread has stopped with
|
|
signal @samp{0}, regardless of whether the target uses some other signal
|
|
as an implementation detail.
|
|
|
|
The stub must support @samp{vCont} if it reports support for
|
|
multiprocess extensions (@pxref{multiprocess extensions}). Note that in
|
|
this case @samp{vCont} actions can be specified to apply to all threads
|
|
in a process by using the @samp{p@var{pid}.-1} form of the
|
|
@var{thread-id}.
|
|
|
|
Reply:
|
|
@xref{Stop Reply Packets}, for the reply specifications.
|
|
|
|
@item vCont?
|
|
@cindex @samp{vCont?} packet
|
|
Request a list of actions supported by the @samp{vCont} packet.
|
|
|
|
Reply:
|
|
@table @samp
|
|
@item vCont@r{[};@var{action}@dots{}@r{]}
|
|
The @samp{vCont} packet is supported. Each @var{action} is a supported
|
|
command in the @samp{vCont} packet.
|
|
@item
|
|
The @samp{vCont} packet is not supported.
|
|
@end table
|
|
|
|
@item vFile:@var{operation}:@var{parameter}@dots{}
|
|
@cindex @samp{vFile} packet
|
|
Perform a file operation on the target system. For details,
|
|
see @ref{Host I/O Packets}.
|
|
|
|
@item vFlashErase:@var{addr},@var{length}
|
|
@cindex @samp{vFlashErase} packet
|
|
Direct the stub to erase @var{length} bytes of flash starting at
|
|
@var{addr}. The region may enclose any number of flash blocks, but
|
|
its start and end must fall on block boundaries, as indicated by the
|
|
flash block size appearing in the memory map (@pxref{Memory Map
|
|
Format}). @value{GDBN} groups flash memory programming operations
|
|
together, and sends a @samp{vFlashDone} request after each group; the
|
|
stub is allowed to delay erase operation until the @samp{vFlashDone}
|
|
packet is received.
|
|
|
|
Reply:
|
|
@table @samp
|
|
@item OK
|
|
for success
|
|
@item E @var{NN}
|
|
for an error
|
|
@end table
|
|
|
|
@item vFlashWrite:@var{addr}:@var{XX@dots{}}
|
|
@cindex @samp{vFlashWrite} packet
|
|
Direct the stub to write data to flash address @var{addr}. The data
|
|
is passed in binary form using the same encoding as for the @samp{X}
|
|
packet (@pxref{Binary Data}). The memory ranges specified by
|
|
@samp{vFlashWrite} packets preceding a @samp{vFlashDone} packet must
|
|
not overlap, and must appear in order of increasing addresses
|
|
(although @samp{vFlashErase} packets for higher addresses may already
|
|
have been received; the ordering is guaranteed only between
|
|
@samp{vFlashWrite} packets). If a packet writes to an address that was
|
|
neither erased by a preceding @samp{vFlashErase} packet nor by some other
|
|
target-specific method, the results are unpredictable.
|
|
|
|
|
|
Reply:
|
|
@table @samp
|
|
@item OK
|
|
for success
|
|
@item E.memtype
|
|
for vFlashWrite addressing non-flash memory
|
|
@item E @var{NN}
|
|
for an error
|
|
@end table
|
|
|
|
@item vFlashDone
|
|
@cindex @samp{vFlashDone} packet
|
|
Indicate to the stub that flash programming operation is finished.
|
|
The stub is permitted to delay or batch the effects of a group of
|
|
@samp{vFlashErase} and @samp{vFlashWrite} packets until a
|
|
@samp{vFlashDone} packet is received. The contents of the affected
|
|
regions of flash memory are unpredictable until the @samp{vFlashDone}
|
|
request is completed.
|
|
|
|
@item vKill;@var{pid}
|
|
@cindex @samp{vKill} packet
|
|
Kill the process with the specified process ID. @var{pid} is a
|
|
hexadecimal integer identifying the process. This packet is used in
|
|
preference to @samp{k} when multiprocess protocol extensions are
|
|
supported; see @ref{multiprocess extensions}.
|
|
|
|
Reply:
|
|
@table @samp
|
|
@item E @var{nn}
|
|
for an error
|
|
@item OK
|
|
for success
|
|
@end table
|
|
|
|
@item vRun;@var{filename}@r{[};@var{argument}@r{]}@dots{}
|
|
@cindex @samp{vRun} packet
|
|
Run the program @var{filename}, passing it each @var{argument} on its
|
|
command line. The file and arguments are hex-encoded strings. If
|
|
@var{filename} is an empty string, the stub may use a default program
|
|
(e.g.@: the last program run). The program is created in the stopped
|
|
state.
|
|
|
|
@c FIXME: What about non-stop mode?
|
|
|
|
This packet is only available in extended mode (@pxref{extended mode}).
|
|
|
|
Reply:
|
|
@table @samp
|
|
@item E @var{nn}
|
|
for an error
|
|
@item @r{Any stop packet}
|
|
for success (@pxref{Stop Reply Packets})
|
|
@end table
|
|
|
|
@item vStopped
|
|
@anchor{vStopped packet}
|
|
@cindex @samp{vStopped} packet
|
|
|
|
In non-stop mode (@pxref{Remote Non-Stop}), acknowledge a previous stop
|
|
reply and prompt for the stub to report another one.
|
|
|
|
Reply:
|
|
@table @samp
|
|
@item @r{Any stop packet}
|
|
if there is another unreported stop event (@pxref{Stop Reply Packets})
|
|
@item OK
|
|
if there are no unreported stop events
|
|
@end table
|
|
|
|
@item X @var{addr},@var{length}:@var{XX@dots{}}
|
|
@anchor{X packet}
|
|
@cindex @samp{X} packet
|
|
Write data to memory, where the data is transmitted in binary.
|
|
@var{addr} is address, @var{length} is number of bytes,
|
|
@samp{@var{XX}@dots{}} is binary data (@pxref{Binary Data}).
|
|
|
|
Reply:
|
|
@table @samp
|
|
@item OK
|
|
for success
|
|
@item E @var{NN}
|
|
for an error
|
|
@end table
|
|
|
|
@item z @var{type},@var{addr},@var{kind}
|
|
@itemx Z @var{type},@var{addr},@var{kind}
|
|
@anchor{insert breakpoint or watchpoint packet}
|
|
@cindex @samp{z} packet
|
|
@cindex @samp{Z} packets
|
|
Insert (@samp{Z}) or remove (@samp{z}) a @var{type} breakpoint or
|
|
watchpoint starting at address @var{address} of kind @var{kind}.
|
|
|
|
Each breakpoint and watchpoint packet @var{type} is documented
|
|
separately.
|
|
|
|
@emph{Implementation notes: A remote target shall return an empty string
|
|
for an unrecognized breakpoint or watchpoint packet @var{type}. A
|
|
remote target shall support either both or neither of a given
|
|
@samp{Z@var{type}@dots{}} and @samp{z@var{type}@dots{}} packet pair. To
|
|
avoid potential problems with duplicate packets, the operations should
|
|
be implemented in an idempotent way.}
|
|
|
|
@item z0,@var{addr},@var{kind}
|
|
@itemx Z0,@var{addr},@var{kind}@r{[};@var{cond_list}@dots{}@r{]}@r{[};cmds:@var{persist},@var{cmd_list}@dots{}@r{]}
|
|
@cindex @samp{z0} packet
|
|
@cindex @samp{Z0} packet
|
|
Insert (@samp{Z0}) or remove (@samp{z0}) a memory breakpoint at address
|
|
@var{addr} of type @var{kind}.
|
|
|
|
A memory breakpoint is implemented by replacing the instruction at
|
|
@var{addr} with a software breakpoint or trap instruction. The
|
|
@var{kind} is target-specific and typically indicates the size of
|
|
the breakpoint in bytes that should be inserted. E.g., the @sc{arm}
|
|
and @sc{mips} can insert either a 2 or 4 byte breakpoint. Some
|
|
architectures have additional meanings for @var{kind};
|
|
@var{cond_list} is an optional list of conditional expressions in bytecode
|
|
form that should be evaluated on the target's side. These are the
|
|
conditions that should be taken into consideration when deciding if
|
|
the breakpoint trigger should be reported back to @var{GDBN}.
|
|
|
|
The @var{cond_list} parameter is comprised of a series of expressions,
|
|
concatenated without separators. Each expression has the following form:
|
|
|
|
@table @samp
|
|
|
|
@item X @var{len},@var{expr}
|
|
@var{len} is the length of the bytecode expression and @var{expr} is the
|
|
actual conditional expression in bytecode form.
|
|
|
|
@end table
|
|
|
|
The optional @var{cmd_list} parameter introduces commands that may be
|
|
run on the target, rather than being reported back to @value{GDBN}.
|
|
The parameter starts with a numeric flag @var{persist}; if the flag is
|
|
nonzero, then the breakpoint may remain active and the commands
|
|
continue to be run even when @value{GDBN} disconnects from the target.
|
|
Following this flag is a series of expressions concatenated with no
|
|
separators. Each expression has the following form:
|
|
|
|
@table @samp
|
|
|
|
@item X @var{len},@var{expr}
|
|
@var{len} is the length of the bytecode expression and @var{expr} is the
|
|
actual conditional expression in bytecode form.
|
|
|
|
@end table
|
|
|
|
see @ref{Architecture-Specific Protocol Details}.
|
|
|
|
@emph{Implementation note: It is possible for a target to copy or move
|
|
code that contains memory breakpoints (e.g., when implementing
|
|
overlays). The behavior of this packet, in the presence of such a
|
|
target, is not defined.}
|
|
|
|
Reply:
|
|
@table @samp
|
|
@item OK
|
|
success
|
|
@item
|
|
not supported
|
|
@item E @var{NN}
|
|
for an error
|
|
@end table
|
|
|
|
@item z1,@var{addr},@var{kind}
|
|
@itemx Z1,@var{addr},@var{kind}@r{[};@var{cond_list}@dots{}@r{]}
|
|
@cindex @samp{z1} packet
|
|
@cindex @samp{Z1} packet
|
|
Insert (@samp{Z1}) or remove (@samp{z1}) a hardware breakpoint at
|
|
address @var{addr}.
|
|
|
|
A hardware breakpoint is implemented using a mechanism that is not
|
|
dependant on being able to modify the target's memory. @var{kind}
|
|
and @var{cond_list} have the same meaning as in @samp{Z0} packets.
|
|
|
|
@emph{Implementation note: A hardware breakpoint is not affected by code
|
|
movement.}
|
|
|
|
Reply:
|
|
@table @samp
|
|
@item OK
|
|
success
|
|
@item
|
|
not supported
|
|
@item E @var{NN}
|
|
for an error
|
|
@end table
|
|
|
|
@item z2,@var{addr},@var{kind}
|
|
@itemx Z2,@var{addr},@var{kind}
|
|
@cindex @samp{z2} packet
|
|
@cindex @samp{Z2} packet
|
|
Insert (@samp{Z2}) or remove (@samp{z2}) a write watchpoint at @var{addr}.
|
|
@var{kind} is interpreted as the number of bytes to watch.
|
|
|
|
Reply:
|
|
@table @samp
|
|
@item OK
|
|
success
|
|
@item
|
|
not supported
|
|
@item E @var{NN}
|
|
for an error
|
|
@end table
|
|
|
|
@item z3,@var{addr},@var{kind}
|
|
@itemx Z3,@var{addr},@var{kind}
|
|
@cindex @samp{z3} packet
|
|
@cindex @samp{Z3} packet
|
|
Insert (@samp{Z3}) or remove (@samp{z3}) a read watchpoint at @var{addr}.
|
|
@var{kind} is interpreted as the number of bytes to watch.
|
|
|
|
Reply:
|
|
@table @samp
|
|
@item OK
|
|
success
|
|
@item
|
|
not supported
|
|
@item E @var{NN}
|
|
for an error
|
|
@end table
|
|
|
|
@item z4,@var{addr},@var{kind}
|
|
@itemx Z4,@var{addr},@var{kind}
|
|
@cindex @samp{z4} packet
|
|
@cindex @samp{Z4} packet
|
|
Insert (@samp{Z4}) or remove (@samp{z4}) an access watchpoint at @var{addr}.
|
|
@var{kind} is interpreted as the number of bytes to watch.
|
|
|
|
Reply:
|
|
@table @samp
|
|
@item OK
|
|
success
|
|
@item
|
|
not supported
|
|
@item E @var{NN}
|
|
for an error
|
|
@end table
|
|
|
|
@end table
|
|
|
|
@node Stop Reply Packets
|
|
@section Stop Reply Packets
|
|
@cindex stop reply packets
|
|
|
|
The @samp{C}, @samp{c}, @samp{S}, @samp{s}, @samp{vCont},
|
|
@samp{vAttach}, @samp{vRun}, @samp{vStopped}, and @samp{?} packets can
|
|
receive any of the below as a reply. Except for @samp{?}
|
|
and @samp{vStopped}, that reply is only returned
|
|
when the target halts. In the below the exact meaning of @dfn{signal
|
|
number} is defined by the header @file{include/gdb/signals.h} in the
|
|
@value{GDBN} source code.
|
|
|
|
As in the description of request packets, we include spaces in the
|
|
reply templates for clarity; these are not part of the reply packet's
|
|
syntax. No @value{GDBN} stop reply packet uses spaces to separate its
|
|
components.
|
|
|
|
@table @samp
|
|
|
|
@item S @var{AA}
|
|
The program received signal number @var{AA} (a two-digit hexadecimal
|
|
number). This is equivalent to a @samp{T} response with no
|
|
@var{n}:@var{r} pairs.
|
|
|
|
@item T @var{AA} @var{n1}:@var{r1};@var{n2}:@var{r2};@dots{}
|
|
@cindex @samp{T} packet reply
|
|
The program received signal number @var{AA} (a two-digit hexadecimal
|
|
number). This is equivalent to an @samp{S} response, except that the
|
|
@samp{@var{n}:@var{r}} pairs can carry values of important registers
|
|
and other information directly in the stop reply packet, reducing
|
|
round-trip latency. Single-step and breakpoint traps are reported
|
|
this way. Each @samp{@var{n}:@var{r}} pair is interpreted as follows:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
If @var{n} is a hexadecimal number, it is a register number, and the
|
|
corresponding @var{r} gives that register's value. @var{r} is a
|
|
series of bytes in target byte order, with each byte given by a
|
|
two-digit hex number.
|
|
|
|
@item
|
|
If @var{n} is @samp{thread}, then @var{r} is the @var{thread-id} of
|
|
the stopped thread, as specified in @ref{thread-id syntax}.
|
|
|
|
@item
|
|
If @var{n} is @samp{core}, then @var{r} is the hexadecimal number of
|
|
the core on which the stop event was detected.
|
|
|
|
@item
|
|
If @var{n} is a recognized @dfn{stop reason}, it describes a more
|
|
specific event that stopped the target. The currently defined stop
|
|
reasons are listed below. @var{aa} should be @samp{05}, the trap
|
|
signal. At most one stop reason should be present.
|
|
|
|
@item
|
|
Otherwise, @value{GDBN} should ignore this @samp{@var{n}:@var{r}} pair
|
|
and go on to the next; this allows us to extend the protocol in the
|
|
future.
|
|
@end itemize
|
|
|
|
The currently defined stop reasons are:
|
|
|
|
@table @samp
|
|
@item watch
|
|
@itemx rwatch
|
|
@itemx awatch
|
|
The packet indicates a watchpoint hit, and @var{r} is the data address, in
|
|
hex.
|
|
|
|
@cindex shared library events, remote reply
|
|
@item library
|
|
The packet indicates that the loaded libraries have changed.
|
|
@value{GDBN} should use @samp{qXfer:libraries:read} to fetch a new
|
|
list of loaded libraries. @var{r} is ignored.
|
|
|
|
@cindex replay log events, remote reply
|
|
@item replaylog
|
|
The packet indicates that the target cannot continue replaying
|
|
logged execution events, because it has reached the end (or the
|
|
beginning when executing backward) of the log. The value of @var{r}
|
|
will be either @samp{begin} or @samp{end}. @xref{Reverse Execution},
|
|
for more information.
|
|
@end table
|
|
|
|
@item W @var{AA}
|
|
@itemx W @var{AA} ; process:@var{pid}
|
|
The process exited, and @var{AA} is the exit status. This is only
|
|
applicable to certain targets.
|
|
|
|
The second form of the response, including the process ID of the exited
|
|
process, can be used only when @value{GDBN} has reported support for
|
|
multiprocess protocol extensions; see @ref{multiprocess extensions}.
|
|
The @var{pid} is formatted as a big-endian hex string.
|
|
|
|
@item X @var{AA}
|
|
@itemx X @var{AA} ; process:@var{pid}
|
|
The process terminated with signal @var{AA}.
|
|
|
|
The second form of the response, including the process ID of the
|
|
terminated process, can be used only when @value{GDBN} has reported
|
|
support for multiprocess protocol extensions; see @ref{multiprocess
|
|
extensions}. The @var{pid} is formatted as a big-endian hex string.
|
|
|
|
@item O @var{XX}@dots{}
|
|
@samp{@var{XX}@dots{}} is hex encoding of @sc{ascii} data, to be
|
|
written as the program's console output. This can happen at any time
|
|
while the program is running and the debugger should continue to wait
|
|
for @samp{W}, @samp{T}, etc. This reply is not permitted in non-stop mode.
|
|
|
|
@item F @var{call-id},@var{parameter}@dots{}
|
|
@var{call-id} is the identifier which says which host system call should
|
|
be called. This is just the name of the function. Translation into the
|
|
correct system call is only applicable as it's defined in @value{GDBN}.
|
|
@xref{File-I/O Remote Protocol Extension}, for a list of implemented
|
|
system calls.
|
|
|
|
@samp{@var{parameter}@dots{}} is a list of parameters as defined for
|
|
this very system call.
|
|
|
|
The target replies with this packet when it expects @value{GDBN} to
|
|
call a host system call on behalf of the target. @value{GDBN} replies
|
|
with an appropriate @samp{F} packet and keeps up waiting for the next
|
|
reply packet from the target. The latest @samp{C}, @samp{c}, @samp{S}
|
|
or @samp{s} action is expected to be continued. @xref{File-I/O Remote
|
|
Protocol Extension}, for more details.
|
|
|
|
@end table
|
|
|
|
@node General Query Packets
|
|
@section General Query Packets
|
|
@cindex remote query requests
|
|
|
|
Packets starting with @samp{q} are @dfn{general query packets};
|
|
packets starting with @samp{Q} are @dfn{general set packets}. General
|
|
query and set packets are a semi-unified form for retrieving and
|
|
sending information to and from the stub.
|
|
|
|
The initial letter of a query or set packet is followed by a name
|
|
indicating what sort of thing the packet applies to. For example,
|
|
@value{GDBN} may use a @samp{qSymbol} packet to exchange symbol
|
|
definitions with the stub. These packet names follow some
|
|
conventions:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
The name must not contain commas, colons or semicolons.
|
|
@item
|
|
Most @value{GDBN} query and set packets have a leading upper case
|
|
letter.
|
|
@item
|
|
The names of custom vendor packets should use a company prefix, in
|
|
lower case, followed by a period. For example, packets designed at
|
|
the Acme Corporation might begin with @samp{qacme.foo} (for querying
|
|
foos) or @samp{Qacme.bar} (for setting bars).
|
|
@end itemize
|
|
|
|
The name of a query or set packet should be separated from any
|
|
parameters by a @samp{:}; the parameters themselves should be
|
|
separated by @samp{,} or @samp{;}. Stubs must be careful to match the
|
|
full packet name, and check for a separator or the end of the packet,
|
|
in case two packet names share a common prefix. New packets should not begin
|
|
with @samp{qC}, @samp{qP}, or @samp{qL}@footnote{The @samp{qP} and @samp{qL}
|
|
packets predate these conventions, and have arguments without any terminator
|
|
for the packet name; we suspect they are in widespread use in places that
|
|
are difficult to upgrade. The @samp{qC} packet has no arguments, but some
|
|
existing stubs (e.g.@: RedBoot) are known to not check for the end of the
|
|
packet.}.
|
|
|
|
Like the descriptions of the other packets, each description here
|
|
has a template showing the packet's overall syntax, followed by an
|
|
explanation of the packet's meaning. We include spaces in some of the
|
|
templates for clarity; these are not part of the packet's syntax. No
|
|
@value{GDBN} packet uses spaces to separate its components.
|
|
|
|
Here are the currently defined query and set packets:
|
|
|
|
@table @samp
|
|
|
|
@item QAgent:1
|
|
@item QAgent:0
|
|
Turn on or off the agent as a helper to perform some debugging operations
|
|
delegated from @value{GDBN} (@pxref{Control Agent}).
|
|
|
|
@item QAllow:@var{op}:@var{val}@dots{}
|
|
@cindex @samp{QAllow} packet
|
|
Specify which operations @value{GDBN} expects to request of the
|
|
target, as a semicolon-separated list of operation name and value
|
|
pairs. Possible values for @var{op} include @samp{WriteReg},
|
|
@samp{WriteMem}, @samp{InsertBreak}, @samp{InsertTrace},
|
|
@samp{InsertFastTrace}, and @samp{Stop}. @var{val} is either 0,
|
|
indicating that @value{GDBN} will not request the operation, or 1,
|
|
indicating that it may. (The target can then use this to set up its
|
|
own internals optimally, for instance if the debugger never expects to
|
|
insert breakpoints, it may not need to install its own trap handler.)
|
|
|
|
@item qC
|
|
@cindex current thread, remote request
|
|
@cindex @samp{qC} packet
|
|
Return the current thread ID.
|
|
|
|
Reply:
|
|
@table @samp
|
|
@item QC @var{thread-id}
|
|
Where @var{thread-id} is a thread ID as documented in
|
|
@ref{thread-id syntax}.
|
|
@item @r{(anything else)}
|
|
Any other reply implies the old thread ID.
|
|
@end table
|
|
|
|
@item qCRC:@var{addr},@var{length}
|
|
@cindex CRC of memory block, remote request
|
|
@cindex @samp{qCRC} packet
|
|
Compute the CRC checksum of a block of memory using CRC-32 defined in
|
|
IEEE 802.3. The CRC is computed byte at a time, taking the most
|
|
significant bit of each byte first. The initial pattern code
|
|
@code{0xffffffff} is used to ensure leading zeros affect the CRC.
|
|
|
|
@emph{Note:} This is the same CRC used in validating separate debug
|
|
files (@pxref{Separate Debug Files, , Debugging Information in Separate
|
|
Files}). However the algorithm is slightly different. When validating
|
|
separate debug files, the CRC is computed taking the @emph{least}
|
|
significant bit of each byte first, and the final result is inverted to
|
|
detect trailing zeros.
|
|
|
|
Reply:
|
|
@table @samp
|
|
@item E @var{NN}
|
|
An error (such as memory fault)
|
|
@item C @var{crc32}
|
|
The specified memory region's checksum is @var{crc32}.
|
|
@end table
|
|
|
|
@item QDisableRandomization:@var{value}
|
|
@cindex disable address space randomization, remote request
|
|
@cindex @samp{QDisableRandomization} packet
|
|
Some target operating systems will randomize the virtual address space
|
|
of the inferior process as a security feature, but provide a feature
|
|
to disable such randomization, e.g.@: to allow for a more deterministic
|
|
debugging experience. On such systems, this packet with a @var{value}
|
|
of 1 directs the target to disable address space randomization for
|
|
processes subsequently started via @samp{vRun} packets, while a packet
|
|
with a @var{value} of 0 tells the target to enable address space
|
|
randomization.
|
|
|
|
This packet is only available in extended mode (@pxref{extended mode}).
|
|
|
|
Reply:
|
|
@table @samp
|
|
@item OK
|
|
The request succeeded.
|
|
|
|
@item E @var{nn}
|
|
An error occurred. @var{nn} are hex digits.
|
|
|
|
@item
|
|
An empty reply indicates that @samp{QDisableRandomization} is not supported
|
|
by the stub.
|
|
@end table
|
|
|
|
This packet is not probed by default; the remote stub must request it,
|
|
by supplying an appropriate @samp{qSupported} response (@pxref{qSupported}).
|
|
This should only be done on targets that actually support disabling
|
|
address space randomization.
|
|
|
|
@item qfThreadInfo
|
|
@itemx qsThreadInfo
|
|
@cindex list active threads, remote request
|
|
@cindex @samp{qfThreadInfo} packet
|
|
@cindex @samp{qsThreadInfo} packet
|
|
Obtain a list of all active thread IDs from the target (OS). Since there
|
|
may be too many active threads to fit into one reply packet, this query
|
|
works iteratively: it may require more than one query/reply sequence to
|
|
obtain the entire list of threads. The first query of the sequence will
|
|
be the @samp{qfThreadInfo} query; subsequent queries in the
|
|
sequence will be the @samp{qsThreadInfo} query.
|
|
|
|
NOTE: This packet replaces the @samp{qL} query (see below).
|
|
|
|
Reply:
|
|
@table @samp
|
|
@item m @var{thread-id}
|
|
A single thread ID
|
|
@item m @var{thread-id},@var{thread-id}@dots{}
|
|
a comma-separated list of thread IDs
|
|
@item l
|
|
(lower case letter @samp{L}) denotes end of list.
|
|
@end table
|
|
|
|
In response to each query, the target will reply with a list of one or
|
|
more thread IDs, separated by commas.
|
|
@value{GDBN} will respond to each reply with a request for more thread
|
|
ids (using the @samp{qs} form of the query), until the target responds
|
|
with @samp{l} (lower-case ell, for @dfn{last}).
|
|
Refer to @ref{thread-id syntax}, for the format of the @var{thread-id}
|
|
fields.
|
|
|
|
@item qGetTLSAddr:@var{thread-id},@var{offset},@var{lm}
|
|
@cindex get thread-local storage address, remote request
|
|
@cindex @samp{qGetTLSAddr} packet
|
|
Fetch the address associated with thread local storage specified
|
|
by @var{thread-id}, @var{offset}, and @var{lm}.
|
|
|
|
@var{thread-id} is the thread ID associated with the
|
|
thread for which to fetch the TLS address. @xref{thread-id syntax}.
|
|
|
|
@var{offset} is the (big endian, hex encoded) offset associated with the
|
|
thread local variable. (This offset is obtained from the debug
|
|
information associated with the variable.)
|
|
|
|
@var{lm} is the (big endian, hex encoded) OS/ABI-specific encoding of the
|
|
load module associated with the thread local storage. For example,
|
|
a @sc{gnu}/Linux system will pass the link map address of the shared
|
|
object associated with the thread local storage under consideration.
|
|
Other operating environments may choose to represent the load module
|
|
differently, so the precise meaning of this parameter will vary.
|
|
|
|
Reply:
|
|
@table @samp
|
|
@item @var{XX}@dots{}
|
|
Hex encoded (big endian) bytes representing the address of the thread
|
|
local storage requested.
|
|
|
|
@item E @var{nn}
|
|
An error occurred. @var{nn} are hex digits.
|
|
|
|
@item
|
|
An empty reply indicates that @samp{qGetTLSAddr} is not supported by the stub.
|
|
@end table
|
|
|
|
@item qGetTIBAddr:@var{thread-id}
|
|
@cindex get thread information block address
|
|
@cindex @samp{qGetTIBAddr} packet
|
|
Fetch address of the Windows OS specific Thread Information Block.
|
|
|
|
@var{thread-id} is the thread ID associated with the thread.
|
|
|
|
Reply:
|
|
@table @samp
|
|
@item @var{XX}@dots{}
|
|
Hex encoded (big endian) bytes representing the linear address of the
|
|
thread information block.
|
|
|
|
@item E @var{nn}
|
|
An error occured. This means that either the thread was not found, or the
|
|
address could not be retrieved.
|
|
|
|
@item
|
|
An empty reply indicates that @samp{qGetTIBAddr} is not supported by the stub.
|
|
@end table
|
|
|
|
@item qL @var{startflag} @var{threadcount} @var{nextthread}
|
|
Obtain thread information from RTOS. Where: @var{startflag} (one hex
|
|
digit) is one to indicate the first query and zero to indicate a
|
|
subsequent query; @var{threadcount} (two hex digits) is the maximum
|
|
number of threads the response packet can contain; and @var{nextthread}
|
|
(eight hex digits), for subsequent queries (@var{startflag} is zero), is
|
|
returned in the response as @var{argthread}.
|
|
|
|
Don't use this packet; use the @samp{qfThreadInfo} query instead (see above).
|
|
|
|
Reply:
|
|
@table @samp
|
|
@item qM @var{count} @var{done} @var{argthread} @var{thread}@dots{}
|
|
Where: @var{count} (two hex digits) is the number of threads being
|
|
returned; @var{done} (one hex digit) is zero to indicate more threads
|
|
and one indicates no further threads; @var{argthreadid} (eight hex
|
|
digits) is @var{nextthread} from the request packet; @var{thread}@dots{}
|
|
is a sequence of thread IDs from the target. @var{threadid} (eight hex
|
|
digits). See @code{remote.c:parse_threadlist_response()}.
|
|
@end table
|
|
|
|
@item qOffsets
|
|
@cindex section offsets, remote request
|
|
@cindex @samp{qOffsets} packet
|
|
Get section offsets that the target used when relocating the downloaded
|
|
image.
|
|
|
|
Reply:
|
|
@table @samp
|
|
@item Text=@var{xxx};Data=@var{yyy}@r{[};Bss=@var{zzz}@r{]}
|
|
Relocate the @code{Text} section by @var{xxx} from its original address.
|
|
Relocate the @code{Data} section by @var{yyy} from its original address.
|
|
If the object file format provides segment information (e.g.@: @sc{elf}
|
|
@samp{PT_LOAD} program headers), @value{GDBN} will relocate entire
|
|
segments by the supplied offsets.
|
|
|
|
@emph{Note: while a @code{Bss} offset may be included in the response,
|
|
@value{GDBN} ignores this and instead applies the @code{Data} offset
|
|
to the @code{Bss} section.}
|
|
|
|
@item TextSeg=@var{xxx}@r{[};DataSeg=@var{yyy}@r{]}
|
|
Relocate the first segment of the object file, which conventionally
|
|
contains program code, to a starting address of @var{xxx}. If
|
|
@samp{DataSeg} is specified, relocate the second segment, which
|
|
conventionally contains modifiable data, to a starting address of
|
|
@var{yyy}. @value{GDBN} will report an error if the object file
|
|
does not contain segment information, or does not contain at least
|
|
as many segments as mentioned in the reply. Extra segments are
|
|
kept at fixed offsets relative to the last relocated segment.
|
|
@end table
|
|
|
|
@item qP @var{mode} @var{thread-id}
|
|
@cindex thread information, remote request
|
|
@cindex @samp{qP} packet
|
|
Returns information on @var{thread-id}. Where: @var{mode} is a hex
|
|
encoded 32 bit mode; @var{thread-id} is a thread ID
|
|
(@pxref{thread-id syntax}).
|
|
|
|
Don't use this packet; use the @samp{qThreadExtraInfo} query instead
|
|
(see below).
|
|
|
|
Reply: see @code{remote.c:remote_unpack_thread_info_response()}.
|
|
|
|
@item QNonStop:1
|
|
@item QNonStop:0
|
|
@cindex non-stop mode, remote request
|
|
@cindex @samp{QNonStop} packet
|
|
@anchor{QNonStop}
|
|
Enter non-stop (@samp{QNonStop:1}) or all-stop (@samp{QNonStop:0}) mode.
|
|
@xref{Remote Non-Stop}, for more information.
|
|
|
|
Reply:
|
|
@table @samp
|
|
@item OK
|
|
The request succeeded.
|
|
|
|
@item E @var{nn}
|
|
An error occurred. @var{nn} are hex digits.
|
|
|
|
@item
|
|
An empty reply indicates that @samp{QNonStop} is not supported by
|
|
the stub.
|
|
@end table
|
|
|
|
This packet is not probed by default; the remote stub must request it,
|
|
by supplying an appropriate @samp{qSupported} response (@pxref{qSupported}).
|
|
Use of this packet is controlled by the @code{set non-stop} command;
|
|
@pxref{Non-Stop Mode}.
|
|
|
|
@item QPassSignals: @var{signal} @r{[};@var{signal}@r{]}@dots{}
|
|
@cindex pass signals to inferior, remote request
|
|
@cindex @samp{QPassSignals} packet
|
|
@anchor{QPassSignals}
|
|
Each listed @var{signal} should be passed directly to the inferior process.
|
|
Signals are numbered identically to continue packets and stop replies
|
|
(@pxref{Stop Reply Packets}). Each @var{signal} list item should be
|
|
strictly greater than the previous item. These signals do not need to stop
|
|
the inferior, or be reported to @value{GDBN}. All other signals should be
|
|
reported to @value{GDBN}. Multiple @samp{QPassSignals} packets do not
|
|
combine; any earlier @samp{QPassSignals} list is completely replaced by the
|
|
new list. This packet improves performance when using @samp{handle
|
|
@var{signal} nostop noprint pass}.
|
|
|
|
Reply:
|
|
@table @samp
|
|
@item OK
|
|
The request succeeded.
|
|
|
|
@item E @var{nn}
|
|
An error occurred. @var{nn} are hex digits.
|
|
|
|
@item
|
|
An empty reply indicates that @samp{QPassSignals} is not supported by
|
|
the stub.
|
|
@end table
|
|
|
|
Use of this packet is controlled by the @code{set remote pass-signals}
|
|
command (@pxref{Remote Configuration, set remote pass-signals}).
|
|
This packet is not probed by default; the remote stub must request it,
|
|
by supplying an appropriate @samp{qSupported} response (@pxref{qSupported}).
|
|
|
|
@item QProgramSignals: @var{signal} @r{[};@var{signal}@r{]}@dots{}
|
|
@cindex signals the inferior may see, remote request
|
|
@cindex @samp{QProgramSignals} packet
|
|
@anchor{QProgramSignals}
|
|
Each listed @var{signal} may be delivered to the inferior process.
|
|
Others should be silently discarded.
|
|
|
|
In some cases, the remote stub may need to decide whether to deliver a
|
|
signal to the program or not without @value{GDBN} involvement. One
|
|
example of that is while detaching --- the program's threads may have
|
|
stopped for signals that haven't yet had a chance of being reported to
|
|
@value{GDBN}, and so the remote stub can use the signal list specified
|
|
by this packet to know whether to deliver or ignore those pending
|
|
signals.
|
|
|
|
This does not influence whether to deliver a signal as requested by a
|
|
resumption packet (@pxref{vCont packet}).
|
|
|
|
Signals are numbered identically to continue packets and stop replies
|
|
(@pxref{Stop Reply Packets}). Each @var{signal} list item should be
|
|
strictly greater than the previous item. Multiple
|
|
@samp{QProgramSignals} packets do not combine; any earlier
|
|
@samp{QProgramSignals} list is completely replaced by the new list.
|
|
|
|
Reply:
|
|
@table @samp
|
|
@item OK
|
|
The request succeeded.
|
|
|
|
@item E @var{nn}
|
|
An error occurred. @var{nn} are hex digits.
|
|
|
|
@item
|
|
An empty reply indicates that @samp{QProgramSignals} is not supported
|
|
by the stub.
|
|
@end table
|
|
|
|
Use of this packet is controlled by the @code{set remote program-signals}
|
|
command (@pxref{Remote Configuration, set remote program-signals}).
|
|
This packet is not probed by default; the remote stub must request it,
|
|
by supplying an appropriate @samp{qSupported} response (@pxref{qSupported}).
|
|
|
|
@item qRcmd,@var{command}
|
|
@cindex execute remote command, remote request
|
|
@cindex @samp{qRcmd} packet
|
|
@var{command} (hex encoded) is passed to the local interpreter for
|
|
execution. Invalid commands should be reported using the output
|
|
string. Before the final result packet, the target may also respond
|
|
with a number of intermediate @samp{O@var{output}} console output
|
|
packets. @emph{Implementors should note that providing access to a
|
|
stubs's interpreter may have security implications}.
|
|
|
|
Reply:
|
|
@table @samp
|
|
@item OK
|
|
A command response with no output.
|
|
@item @var{OUTPUT}
|
|
A command response with the hex encoded output string @var{OUTPUT}.
|
|
@item E @var{NN}
|
|
Indicate a badly formed request.
|
|
@item
|
|
An empty reply indicates that @samp{qRcmd} is not recognized.
|
|
@end table
|
|
|
|
(Note that the @code{qRcmd} packet's name is separated from the
|
|
command by a @samp{,}, not a @samp{:}, contrary to the naming
|
|
conventions above. Please don't use this packet as a model for new
|
|
packets.)
|
|
|
|
@item qSearch:memory:@var{address};@var{length};@var{search-pattern}
|
|
@cindex searching memory, in remote debugging
|
|
@cindex @samp{qSearch:memory} packet
|
|
@anchor{qSearch memory}
|
|
Search @var{length} bytes at @var{address} for @var{search-pattern}.
|
|
@var{address} and @var{length} are encoded in hex.
|
|
@var{search-pattern} is a sequence of bytes, hex encoded.
|
|
|
|
Reply:
|
|
@table @samp
|
|
@item 0
|
|
The pattern was not found.
|
|
@item 1,address
|
|
The pattern was found at @var{address}.
|
|
@item E @var{NN}
|
|
A badly formed request or an error was encountered while searching memory.
|
|
@item
|
|
An empty reply indicates that @samp{qSearch:memory} is not recognized.
|
|
@end table
|
|
|
|
@item QStartNoAckMode
|
|
@cindex @samp{QStartNoAckMode} packet
|
|
@anchor{QStartNoAckMode}
|
|
Request that the remote stub disable the normal @samp{+}/@samp{-}
|
|
protocol acknowledgments (@pxref{Packet Acknowledgment}).
|
|
|
|
Reply:
|
|
@table @samp
|
|
@item OK
|
|
The stub has switched to no-acknowledgment mode.
|
|
@value{GDBN} acknowledges this reponse,
|
|
but neither the stub nor @value{GDBN} shall send or expect further
|
|
@samp{+}/@samp{-} acknowledgments in the current connection.
|
|
@item
|
|
An empty reply indicates that the stub does not support no-acknowledgment mode.
|
|
@end table
|
|
|
|
@item qSupported @r{[}:@var{gdbfeature} @r{[};@var{gdbfeature}@r{]}@dots{} @r{]}
|
|
@cindex supported packets, remote query
|
|
@cindex features of the remote protocol
|
|
@cindex @samp{qSupported} packet
|
|
@anchor{qSupported}
|
|
Tell the remote stub about features supported by @value{GDBN}, and
|
|
query the stub for features it supports. This packet allows
|
|
@value{GDBN} and the remote stub to take advantage of each others'
|
|
features. @samp{qSupported} also consolidates multiple feature probes
|
|
at startup, to improve @value{GDBN} performance---a single larger
|
|
packet performs better than multiple smaller probe packets on
|
|
high-latency links. Some features may enable behavior which must not
|
|
be on by default, e.g.@: because it would confuse older clients or
|
|
stubs. Other features may describe packets which could be
|
|
automatically probed for, but are not. These features must be
|
|
reported before @value{GDBN} will use them. This ``default
|
|
unsupported'' behavior is not appropriate for all packets, but it
|
|
helps to keep the initial connection time under control with new
|
|
versions of @value{GDBN} which support increasing numbers of packets.
|
|
|
|
Reply:
|
|
@table @samp
|
|
@item @var{stubfeature} @r{[};@var{stubfeature}@r{]}@dots{}
|
|
The stub supports or does not support each returned @var{stubfeature},
|
|
depending on the form of each @var{stubfeature} (see below for the
|
|
possible forms).
|
|
@item
|
|
An empty reply indicates that @samp{qSupported} is not recognized,
|
|
or that no features needed to be reported to @value{GDBN}.
|
|
@end table
|
|
|
|
The allowed forms for each feature (either a @var{gdbfeature} in the
|
|
@samp{qSupported} packet, or a @var{stubfeature} in the response)
|
|
are:
|
|
|
|
@table @samp
|
|
@item @var{name}=@var{value}
|
|
The remote protocol feature @var{name} is supported, and associated
|
|
with the specified @var{value}. The format of @var{value} depends
|
|
on the feature, but it must not include a semicolon.
|
|
@item @var{name}+
|
|
The remote protocol feature @var{name} is supported, and does not
|
|
need an associated value.
|
|
@item @var{name}-
|
|
The remote protocol feature @var{name} is not supported.
|
|
@item @var{name}?
|
|
The remote protocol feature @var{name} may be supported, and
|
|
@value{GDBN} should auto-detect support in some other way when it is
|
|
needed. This form will not be used for @var{gdbfeature} notifications,
|
|
but may be used for @var{stubfeature} responses.
|
|
@end table
|
|
|
|
Whenever the stub receives a @samp{qSupported} request, the
|
|
supplied set of @value{GDBN} features should override any previous
|
|
request. This allows @value{GDBN} to put the stub in a known
|
|
state, even if the stub had previously been communicating with
|
|
a different version of @value{GDBN}.
|
|
|
|
The following values of @var{gdbfeature} (for the packet sent by @value{GDBN})
|
|
are defined:
|
|
|
|
@table @samp
|
|
@item multiprocess
|
|
This feature indicates whether @value{GDBN} supports multiprocess
|
|
extensions to the remote protocol. @value{GDBN} does not use such
|
|
extensions unless the stub also reports that it supports them by
|
|
including @samp{multiprocess+} in its @samp{qSupported} reply.
|
|
@xref{multiprocess extensions}, for details.
|
|
|
|
@item xmlRegisters
|
|
This feature indicates that @value{GDBN} supports the XML target
|
|
description. If the stub sees @samp{xmlRegisters=} with target
|
|
specific strings separated by a comma, it will report register
|
|
description.
|
|
|
|
@item qRelocInsn
|
|
This feature indicates whether @value{GDBN} supports the
|
|
@samp{qRelocInsn} packet (@pxref{Tracepoint Packets,,Relocate
|
|
instruction reply packet}).
|
|
@end table
|
|
|
|
Stubs should ignore any unknown values for
|
|
@var{gdbfeature}. Any @value{GDBN} which sends a @samp{qSupported}
|
|
packet supports receiving packets of unlimited length (earlier
|
|
versions of @value{GDBN} may reject overly long responses). Additional values
|
|
for @var{gdbfeature} may be defined in the future to let the stub take
|
|
advantage of new features in @value{GDBN}, e.g.@: incompatible
|
|
improvements in the remote protocol---the @samp{multiprocess} feature is
|
|
an example of such a feature. The stub's reply should be independent
|
|
of the @var{gdbfeature} entries sent by @value{GDBN}; first @value{GDBN}
|
|
describes all the features it supports, and then the stub replies with
|
|
all the features it supports.
|
|
|
|
Similarly, @value{GDBN} will silently ignore unrecognized stub feature
|
|
responses, as long as each response uses one of the standard forms.
|
|
|
|
Some features are flags. A stub which supports a flag feature
|
|
should respond with a @samp{+} form response. Other features
|
|
require values, and the stub should respond with an @samp{=}
|
|
form response.
|
|
|
|
Each feature has a default value, which @value{GDBN} will use if
|
|
@samp{qSupported} is not available or if the feature is not mentioned
|
|
in the @samp{qSupported} response. The default values are fixed; a
|
|
stub is free to omit any feature responses that match the defaults.
|
|
|
|
Not all features can be probed, but for those which can, the probing
|
|
mechanism is useful: in some cases, a stub's internal
|
|
architecture may not allow the protocol layer to know some information
|
|
about the underlying target in advance. This is especially common in
|
|
stubs which may be configured for multiple targets.
|
|
|
|
These are the currently defined stub features and their properties:
|
|
|
|
@multitable @columnfractions 0.35 0.2 0.12 0.2
|
|
@c NOTE: The first row should be @headitem, but we do not yet require
|
|
@c a new enough version of Texinfo (4.7) to use @headitem.
|
|
@item Feature Name
|
|
@tab Value Required
|
|
@tab Default
|
|
@tab Probe Allowed
|
|
|
|
@item @samp{PacketSize}
|
|
@tab Yes
|
|
@tab @samp{-}
|
|
@tab No
|
|
|
|
@item @samp{qXfer:auxv:read}
|
|
@tab No
|
|
@tab @samp{-}
|
|
@tab Yes
|
|
|
|
@item @samp{qXfer:features:read}
|
|
@tab No
|
|
@tab @samp{-}
|
|
@tab Yes
|
|
|
|
@item @samp{qXfer:libraries:read}
|
|
@tab No
|
|
@tab @samp{-}
|
|
@tab Yes
|
|
|
|
@item @samp{qXfer:memory-map:read}
|
|
@tab No
|
|
@tab @samp{-}
|
|
@tab Yes
|
|
|
|
@item @samp{qXfer:sdata:read}
|
|
@tab No
|
|
@tab @samp{-}
|
|
@tab Yes
|
|
|
|
@item @samp{qXfer:spu:read}
|
|
@tab No
|
|
@tab @samp{-}
|
|
@tab Yes
|
|
|
|
@item @samp{qXfer:spu:write}
|
|
@tab No
|
|
@tab @samp{-}
|
|
@tab Yes
|
|
|
|
@item @samp{qXfer:siginfo:read}
|
|
@tab No
|
|
@tab @samp{-}
|
|
@tab Yes
|
|
|
|
@item @samp{qXfer:siginfo:write}
|
|
@tab No
|
|
@tab @samp{-}
|
|
@tab Yes
|
|
|
|
@item @samp{qXfer:threads:read}
|
|
@tab No
|
|
@tab @samp{-}
|
|
@tab Yes
|
|
|
|
@item @samp{qXfer:traceframe-info:read}
|
|
@tab No
|
|
@tab @samp{-}
|
|
@tab Yes
|
|
|
|
@item @samp{qXfer:uib:read}
|
|
@tab No
|
|
@tab @samp{-}
|
|
@tab Yes
|
|
|
|
@item @samp{qXfer:fdpic:read}
|
|
@tab No
|
|
@tab @samp{-}
|
|
@tab Yes
|
|
|
|
@item @samp{QNonStop}
|
|
@tab No
|
|
@tab @samp{-}
|
|
@tab Yes
|
|
|
|
@item @samp{QPassSignals}
|
|
@tab No
|
|
@tab @samp{-}
|
|
@tab Yes
|
|
|
|
@item @samp{QStartNoAckMode}
|
|
@tab No
|
|
@tab @samp{-}
|
|
@tab Yes
|
|
|
|
@item @samp{multiprocess}
|
|
@tab No
|
|
@tab @samp{-}
|
|
@tab No
|
|
|
|
@item @samp{ConditionalBreakpoints}
|
|
@tab No
|
|
@tab @samp{-}
|
|
@tab No
|
|
|
|
@item @samp{ConditionalTracepoints}
|
|
@tab No
|
|
@tab @samp{-}
|
|
@tab No
|
|
|
|
@item @samp{ReverseContinue}
|
|
@tab No
|
|
@tab @samp{-}
|
|
@tab No
|
|
|
|
@item @samp{ReverseStep}
|
|
@tab No
|
|
@tab @samp{-}
|
|
@tab No
|
|
|
|
@item @samp{TracepointSource}
|
|
@tab No
|
|
@tab @samp{-}
|
|
@tab No
|
|
|
|
@item @samp{QAgent}
|
|
@tab No
|
|
@tab @samp{-}
|
|
@tab No
|
|
|
|
@item @samp{QAllow}
|
|
@tab No
|
|
@tab @samp{-}
|
|
@tab No
|
|
|
|
@item @samp{QDisableRandomization}
|
|
@tab No
|
|
@tab @samp{-}
|
|
@tab No
|
|
|
|
@item @samp{EnableDisableTracepoints}
|
|
@tab No
|
|
@tab @samp{-}
|
|
@tab No
|
|
|
|
@item @samp{tracenz}
|
|
@tab No
|
|
@tab @samp{-}
|
|
@tab No
|
|
|
|
@item @samp{BreakpointCommands}
|
|
@tab No
|
|
@tab @samp{-}
|
|
@tab No
|
|
|
|
@end multitable
|
|
|
|
These are the currently defined stub features, in more detail:
|
|
|
|
@table @samp
|
|
@cindex packet size, remote protocol
|
|
@item PacketSize=@var{bytes}
|
|
The remote stub can accept packets up to at least @var{bytes} in
|
|
length. @value{GDBN} will send packets up to this size for bulk
|
|
transfers, and will never send larger packets. This is a limit on the
|
|
data characters in the packet, including the frame and checksum.
|
|
There is no trailing NUL byte in a remote protocol packet; if the stub
|
|
stores packets in a NUL-terminated format, it should allow an extra
|
|
byte in its buffer for the NUL. If this stub feature is not supported,
|
|
@value{GDBN} guesses based on the size of the @samp{g} packet response.
|
|
|
|
@item qXfer:auxv:read
|
|
The remote stub understands the @samp{qXfer:auxv:read} packet
|
|
(@pxref{qXfer auxiliary vector read}).
|
|
|
|
@item qXfer:features:read
|
|
The remote stub understands the @samp{qXfer:features:read} packet
|
|
(@pxref{qXfer target description read}).
|
|
|
|
@item qXfer:libraries:read
|
|
The remote stub understands the @samp{qXfer:libraries:read} packet
|
|
(@pxref{qXfer library list read}).
|
|
|
|
@item qXfer:libraries-svr4:read
|
|
The remote stub understands the @samp{qXfer:libraries-svr4:read} packet
|
|
(@pxref{qXfer svr4 library list read}).
|
|
|
|
@item qXfer:memory-map:read
|
|
The remote stub understands the @samp{qXfer:memory-map:read} packet
|
|
(@pxref{qXfer memory map read}).
|
|
|
|
@item qXfer:sdata:read
|
|
The remote stub understands the @samp{qXfer:sdata:read} packet
|
|
(@pxref{qXfer sdata read}).
|
|
|
|
@item qXfer:spu:read
|
|
The remote stub understands the @samp{qXfer:spu:read} packet
|
|
(@pxref{qXfer spu read}).
|
|
|
|
@item qXfer:spu:write
|
|
The remote stub understands the @samp{qXfer:spu:write} packet
|
|
(@pxref{qXfer spu write}).
|
|
|
|
@item qXfer:siginfo:read
|
|
The remote stub understands the @samp{qXfer:siginfo:read} packet
|
|
(@pxref{qXfer siginfo read}).
|
|
|
|
@item qXfer:siginfo:write
|
|
The remote stub understands the @samp{qXfer:siginfo:write} packet
|
|
(@pxref{qXfer siginfo write}).
|
|
|
|
@item qXfer:threads:read
|
|
The remote stub understands the @samp{qXfer:threads:read} packet
|
|
(@pxref{qXfer threads read}).
|
|
|
|
@item qXfer:traceframe-info:read
|
|
The remote stub understands the @samp{qXfer:traceframe-info:read}
|
|
packet (@pxref{qXfer traceframe info read}).
|
|
|
|
@item qXfer:uib:read
|
|
The remote stub understands the @samp{qXfer:uib:read}
|
|
packet (@pxref{qXfer unwind info block}).
|
|
|
|
@item qXfer:fdpic:read
|
|
The remote stub understands the @samp{qXfer:fdpic:read}
|
|
packet (@pxref{qXfer fdpic loadmap read}).
|
|
|
|
@item QNonStop
|
|
The remote stub understands the @samp{QNonStop} packet
|
|
(@pxref{QNonStop}).
|
|
|
|
@item QPassSignals
|
|
The remote stub understands the @samp{QPassSignals} packet
|
|
(@pxref{QPassSignals}).
|
|
|
|
@item QStartNoAckMode
|
|
The remote stub understands the @samp{QStartNoAckMode} packet and
|
|
prefers to operate in no-acknowledgment mode. @xref{Packet Acknowledgment}.
|
|
|
|
@item multiprocess
|
|
@anchor{multiprocess extensions}
|
|
@cindex multiprocess extensions, in remote protocol
|
|
The remote stub understands the multiprocess extensions to the remote
|
|
protocol syntax. The multiprocess extensions affect the syntax of
|
|
thread IDs in both packets and replies (@pxref{thread-id syntax}), and
|
|
add process IDs to the @samp{D} packet and @samp{W} and @samp{X}
|
|
replies. Note that reporting this feature indicates support for the
|
|
syntactic extensions only, not that the stub necessarily supports
|
|
debugging of more than one process at a time. The stub must not use
|
|
multiprocess extensions in packet replies unless @value{GDBN} has also
|
|
indicated it supports them in its @samp{qSupported} request.
|
|
|
|
@item qXfer:osdata:read
|
|
The remote stub understands the @samp{qXfer:osdata:read} packet
|
|
((@pxref{qXfer osdata read}).
|
|
|
|
@item ConditionalBreakpoints
|
|
The target accepts and implements evaluation of conditional expressions
|
|
defined for breakpoints. The target will only report breakpoint triggers
|
|
when such conditions are true (@pxref{Conditions, ,Break Conditions}).
|
|
|
|
@item ConditionalTracepoints
|
|
The remote stub accepts and implements conditional expressions defined
|
|
for tracepoints (@pxref{Tracepoint Conditions}).
|
|
|
|
@item ReverseContinue
|
|
The remote stub accepts and implements the reverse continue packet
|
|
(@pxref{bc}).
|
|
|
|
@item ReverseStep
|
|
The remote stub accepts and implements the reverse step packet
|
|
(@pxref{bs}).
|
|
|
|
@item TracepointSource
|
|
The remote stub understands the @samp{QTDPsrc} packet that supplies
|
|
the source form of tracepoint definitions.
|
|
|
|
@item QAgent
|
|
The remote stub understands the @samp{QAgent} packet.
|
|
|
|
@item QAllow
|
|
The remote stub understands the @samp{QAllow} packet.
|
|
|
|
@item QDisableRandomization
|
|
The remote stub understands the @samp{QDisableRandomization} packet.
|
|
|
|
@item StaticTracepoint
|
|
@cindex static tracepoints, in remote protocol
|
|
The remote stub supports static tracepoints.
|
|
|
|
@item InstallInTrace
|
|
@anchor{install tracepoint in tracing}
|
|
The remote stub supports installing tracepoint in tracing.
|
|
|
|
@item EnableDisableTracepoints
|
|
The remote stub supports the @samp{QTEnable} (@pxref{QTEnable}) and
|
|
@samp{QTDisable} (@pxref{QTDisable}) packets that allow tracepoints
|
|
to be enabled and disabled while a trace experiment is running.
|
|
|
|
@item tracenz
|
|
@cindex string tracing, in remote protocol
|
|
The remote stub supports the @samp{tracenz} bytecode for collecting strings.
|
|
See @ref{Bytecode Descriptions} for details about the bytecode.
|
|
|
|
@item BreakpointCommands
|
|
@cindex breakpoint commands, in remote protocol
|
|
The remote stub supports running a breakpoint's command list itself,
|
|
rather than reporting the hit to @value{GDBN}.
|
|
|
|
@end table
|
|
|
|
@item qSymbol::
|
|
@cindex symbol lookup, remote request
|
|
@cindex @samp{qSymbol} packet
|
|
Notify the target that @value{GDBN} is prepared to serve symbol lookup
|
|
requests. Accept requests from the target for the values of symbols.
|
|
|
|
Reply:
|
|
@table @samp
|
|
@item OK
|
|
The target does not need to look up any (more) symbols.
|
|
@item qSymbol:@var{sym_name}
|
|
The target requests the value of symbol @var{sym_name} (hex encoded).
|
|
@value{GDBN} may provide the value by using the
|
|
@samp{qSymbol:@var{sym_value}:@var{sym_name}} message, described
|
|
below.
|
|
@end table
|
|
|
|
@item qSymbol:@var{sym_value}:@var{sym_name}
|
|
Set the value of @var{sym_name} to @var{sym_value}.
|
|
|
|
@var{sym_name} (hex encoded) is the name of a symbol whose value the
|
|
target has previously requested.
|
|
|
|
@var{sym_value} (hex) is the value for symbol @var{sym_name}. If
|
|
@value{GDBN} cannot supply a value for @var{sym_name}, then this field
|
|
will be empty.
|
|
|
|
Reply:
|
|
@table @samp
|
|
@item OK
|
|
The target does not need to look up any (more) symbols.
|
|
@item qSymbol:@var{sym_name}
|
|
The target requests the value of a new symbol @var{sym_name} (hex
|
|
encoded). @value{GDBN} will continue to supply the values of symbols
|
|
(if available), until the target ceases to request them.
|
|
@end table
|
|
|
|
@item qTBuffer
|
|
@item QTBuffer
|
|
@item QTDisconnected
|
|
@itemx QTDP
|
|
@itemx QTDPsrc
|
|
@itemx QTDV
|
|
@itemx qTfP
|
|
@itemx qTfV
|
|
@itemx QTFrame
|
|
@itemx qTMinFTPILen
|
|
|
|
@xref{Tracepoint Packets}.
|
|
|
|
@item qThreadExtraInfo,@var{thread-id}
|
|
@cindex thread attributes info, remote request
|
|
@cindex @samp{qThreadExtraInfo} packet
|
|
Obtain a printable string description of a thread's attributes from
|
|
the target OS. @var{thread-id} is a thread ID;
|
|
see @ref{thread-id syntax}. This
|
|
string may contain anything that the target OS thinks is interesting
|
|
for @value{GDBN} to tell the user about the thread. The string is
|
|
displayed in @value{GDBN}'s @code{info threads} display. Some
|
|
examples of possible thread extra info strings are @samp{Runnable}, or
|
|
@samp{Blocked on Mutex}.
|
|
|
|
Reply:
|
|
@table @samp
|
|
@item @var{XX}@dots{}
|
|
Where @samp{@var{XX}@dots{}} is a hex encoding of @sc{ascii} data,
|
|
comprising the printable string containing the extra information about
|
|
the thread's attributes.
|
|
@end table
|
|
|
|
(Note that the @code{qThreadExtraInfo} packet's name is separated from
|
|
the command by a @samp{,}, not a @samp{:}, contrary to the naming
|
|
conventions above. Please don't use this packet as a model for new
|
|
packets.)
|
|
|
|
@item QTNotes
|
|
@item qTP
|
|
@item QTSave
|
|
@item qTsP
|
|
@item qTsV
|
|
@itemx QTStart
|
|
@itemx QTStop
|
|
@itemx QTEnable
|
|
@itemx QTDisable
|
|
@itemx QTinit
|
|
@itemx QTro
|
|
@itemx qTStatus
|
|
@itemx qTV
|
|
@itemx qTfSTM
|
|
@itemx qTsSTM
|
|
@itemx qTSTMat
|
|
@xref{Tracepoint Packets}.
|
|
|
|
@item qXfer:@var{object}:read:@var{annex}:@var{offset},@var{length}
|
|
@cindex read special object, remote request
|
|
@cindex @samp{qXfer} packet
|
|
@anchor{qXfer read}
|
|
Read uninterpreted bytes from the target's special data area
|
|
identified by the keyword @var{object}. Request @var{length} bytes
|
|
starting at @var{offset} bytes into the data. The content and
|
|
encoding of @var{annex} is specific to @var{object}; it can supply
|
|
additional details about what data to access.
|
|
|
|
Here are the specific requests of this form defined so far. All
|
|
@samp{qXfer:@var{object}:read:@dots{}} requests use the same reply
|
|
formats, listed below.
|
|
|
|
@table @samp
|
|
@item qXfer:auxv:read::@var{offset},@var{length}
|
|
@anchor{qXfer auxiliary vector read}
|
|
Access the target's @dfn{auxiliary vector}. @xref{OS Information,
|
|
auxiliary vector}. Note @var{annex} must be empty.
|
|
|
|
This packet is not probed by default; the remote stub must request it,
|
|
by supplying an appropriate @samp{qSupported} response (@pxref{qSupported}).
|
|
|
|
@item qXfer:features:read:@var{annex}:@var{offset},@var{length}
|
|
@anchor{qXfer target description read}
|
|
Access the @dfn{target description}. @xref{Target Descriptions}. The
|
|
annex specifies which XML document to access. The main description is
|
|
always loaded from the @samp{target.xml} annex.
|
|
|
|
This packet is not probed by default; the remote stub must request it,
|
|
by supplying an appropriate @samp{qSupported} response (@pxref{qSupported}).
|
|
|
|
@item qXfer:libraries:read:@var{annex}:@var{offset},@var{length}
|
|
@anchor{qXfer library list read}
|
|
Access the target's list of loaded libraries. @xref{Library List Format}.
|
|
The annex part of the generic @samp{qXfer} packet must be empty
|
|
(@pxref{qXfer read}).
|
|
|
|
Targets which maintain a list of libraries in the program's memory do
|
|
not need to implement this packet; it is designed for platforms where
|
|
the operating system manages the list of loaded libraries.
|
|
|
|
This packet is not probed by default; the remote stub must request it,
|
|
by supplying an appropriate @samp{qSupported} response (@pxref{qSupported}).
|
|
|
|
@item qXfer:libraries-svr4:read:@var{annex}:@var{offset},@var{length}
|
|
@anchor{qXfer svr4 library list read}
|
|
Access the target's list of loaded libraries when the target is an SVR4
|
|
platform. @xref{Library List Format for SVR4 Targets}. The annex part
|
|
of the generic @samp{qXfer} packet must be empty (@pxref{qXfer read}).
|
|
|
|
This packet is optional for better performance on SVR4 targets.
|
|
@value{GDBN} uses memory read packets to read the SVR4 library list otherwise.
|
|
|
|
This packet is not probed by default; the remote stub must request it,
|
|
by supplying an appropriate @samp{qSupported} response (@pxref{qSupported}).
|
|
|
|
@item qXfer:memory-map:read::@var{offset},@var{length}
|
|
@anchor{qXfer memory map read}
|
|
Access the target's @dfn{memory-map}. @xref{Memory Map Format}. The
|
|
annex part of the generic @samp{qXfer} packet must be empty
|
|
(@pxref{qXfer read}).
|
|
|
|
This packet is not probed by default; the remote stub must request it,
|
|
by supplying an appropriate @samp{qSupported} response (@pxref{qSupported}).
|
|
|
|
@item qXfer:sdata:read::@var{offset},@var{length}
|
|
@anchor{qXfer sdata read}
|
|
|
|
Read contents of the extra collected static tracepoint marker
|
|
information. The annex part of the generic @samp{qXfer} packet must
|
|
be empty (@pxref{qXfer read}). @xref{Tracepoint Actions,,Tracepoint
|
|
Action Lists}.
|
|
|
|
This packet is not probed by default; the remote stub must request it,
|
|
by supplying an appropriate @samp{qSupported} response
|
|
(@pxref{qSupported}).
|
|
|
|
@item qXfer:siginfo:read::@var{offset},@var{length}
|
|
@anchor{qXfer siginfo read}
|
|
Read contents of the extra signal information on the target
|
|
system. The annex part of the generic @samp{qXfer} packet must be
|
|
empty (@pxref{qXfer read}).
|
|
|
|
This packet is not probed by default; the remote stub must request it,
|
|
by supplying an appropriate @samp{qSupported} response
|
|
(@pxref{qSupported}).
|
|
|
|
@item qXfer:spu:read:@var{annex}:@var{offset},@var{length}
|
|
@anchor{qXfer spu read}
|
|
Read contents of an @code{spufs} file on the target system. The
|
|
annex specifies which file to read; it must be of the form
|
|
@file{@var{id}/@var{name}}, where @var{id} specifies an SPU context ID
|
|
in the target process, and @var{name} identifes the @code{spufs} file
|
|
in that context to be accessed.
|
|
|
|
This packet is not probed by default; the remote stub must request it,
|
|
by supplying an appropriate @samp{qSupported} response
|
|
(@pxref{qSupported}).
|
|
|
|
@item qXfer:threads:read::@var{offset},@var{length}
|
|
@anchor{qXfer threads read}
|
|
Access the list of threads on target. @xref{Thread List Format}. The
|
|
annex part of the generic @samp{qXfer} packet must be empty
|
|
(@pxref{qXfer read}).
|
|
|
|
This packet is not probed by default; the remote stub must request it,
|
|
by supplying an appropriate @samp{qSupported} response (@pxref{qSupported}).
|
|
|
|
@item qXfer:traceframe-info:read::@var{offset},@var{length}
|
|
@anchor{qXfer traceframe info read}
|
|
|
|
Return a description of the current traceframe's contents.
|
|
@xref{Traceframe Info Format}. The annex part of the generic
|
|
@samp{qXfer} packet must be empty (@pxref{qXfer read}).
|
|
|
|
This packet is not probed by default; the remote stub must request it,
|
|
by supplying an appropriate @samp{qSupported} response (@pxref{qSupported}).
|
|
|
|
@item qXfer:uib:read:@var{pc}:@var{offset},@var{length}
|
|
@anchor{qXfer unwind info block}
|
|
|
|
Return the unwind information block for @var{pc}. This packet is used
|
|
on OpenVMS/ia64 to ask the kernel unwind information.
|
|
|
|
This packet is not probed by default.
|
|
|
|
@item qXfer:fdpic:read:@var{annex}:@var{offset},@var{length}
|
|
@anchor{qXfer fdpic loadmap read}
|
|
Read contents of @code{loadmap}s on the target system. The
|
|
annex, either @samp{exec} or @samp{interp}, specifies which @code{loadmap},
|
|
executable @code{loadmap} or interpreter @code{loadmap} to read.
|
|
|
|
This packet is not probed by default; the remote stub must request it,
|
|
by supplying an appropriate @samp{qSupported} response (@pxref{qSupported}).
|
|
|
|
@item qXfer:osdata:read::@var{offset},@var{length}
|
|
@anchor{qXfer osdata read}
|
|
Access the target's @dfn{operating system information}.
|
|
@xref{Operating System Information}.
|
|
|
|
@end table
|
|
|
|
Reply:
|
|
@table @samp
|
|
@item m @var{data}
|
|
Data @var{data} (@pxref{Binary Data}) has been read from the
|
|
target. There may be more data at a higher address (although
|
|
it is permitted to return @samp{m} even for the last valid
|
|
block of data, as long as at least one byte of data was read).
|
|
@var{data} may have fewer bytes than the @var{length} in the
|
|
request.
|
|
|
|
@item l @var{data}
|
|
Data @var{data} (@pxref{Binary Data}) has been read from the target.
|
|
There is no more data to be read. @var{data} may have fewer bytes
|
|
than the @var{length} in the request.
|
|
|
|
@item l
|
|
The @var{offset} in the request is at the end of the data.
|
|
There is no more data to be read.
|
|
|
|
@item E00
|
|
The request was malformed, or @var{annex} was invalid.
|
|
|
|
@item E @var{nn}
|
|
The offset was invalid, or there was an error encountered reading the data.
|
|
@var{nn} is a hex-encoded @code{errno} value.
|
|
|
|
@item
|
|
An empty reply indicates the @var{object} string was not recognized by
|
|
the stub, or that the object does not support reading.
|
|
@end table
|
|
|
|
@item qXfer:@var{object}:write:@var{annex}:@var{offset}:@var{data}@dots{}
|
|
@cindex write data into object, remote request
|
|
@anchor{qXfer write}
|
|
Write uninterpreted bytes into the target's special data area
|
|
identified by the keyword @var{object}, starting at @var{offset} bytes
|
|
into the data. @var{data}@dots{} is the binary-encoded data
|
|
(@pxref{Binary Data}) to be written. The content and encoding of @var{annex}
|
|
is specific to @var{object}; it can supply additional details about what data
|
|
to access.
|
|
|
|
Here are the specific requests of this form defined so far. All
|
|
@samp{qXfer:@var{object}:write:@dots{}} requests use the same reply
|
|
formats, listed below.
|
|
|
|
@table @samp
|
|
@item qXfer:siginfo:write::@var{offset}:@var{data}@dots{}
|
|
@anchor{qXfer siginfo write}
|
|
Write @var{data} to the extra signal information on the target system.
|
|
The annex part of the generic @samp{qXfer} packet must be
|
|
empty (@pxref{qXfer write}).
|
|
|
|
This packet is not probed by default; the remote stub must request it,
|
|
by supplying an appropriate @samp{qSupported} response
|
|
(@pxref{qSupported}).
|
|
|
|
@item qXfer:spu:write:@var{annex}:@var{offset}:@var{data}@dots{}
|
|
@anchor{qXfer spu write}
|
|
Write @var{data} to an @code{spufs} file on the target system. The
|
|
annex specifies which file to write; it must be of the form
|
|
@file{@var{id}/@var{name}}, where @var{id} specifies an SPU context ID
|
|
in the target process, and @var{name} identifes the @code{spufs} file
|
|
in that context to be accessed.
|
|
|
|
This packet is not probed by default; the remote stub must request it,
|
|
by supplying an appropriate @samp{qSupported} response (@pxref{qSupported}).
|
|
@end table
|
|
|
|
Reply:
|
|
@table @samp
|
|
@item @var{nn}
|
|
@var{nn} (hex encoded) is the number of bytes written.
|
|
This may be fewer bytes than supplied in the request.
|
|
|
|
@item E00
|
|
The request was malformed, or @var{annex} was invalid.
|
|
|
|
@item E @var{nn}
|
|
The offset was invalid, or there was an error encountered writing the data.
|
|
@var{nn} is a hex-encoded @code{errno} value.
|
|
|
|
@item
|
|
An empty reply indicates the @var{object} string was not
|
|
recognized by the stub, or that the object does not support writing.
|
|
@end table
|
|
|
|
@item qXfer:@var{object}:@var{operation}:@dots{}
|
|
Requests of this form may be added in the future. When a stub does
|
|
not recognize the @var{object} keyword, or its support for
|
|
@var{object} does not recognize the @var{operation} keyword, the stub
|
|
must respond with an empty packet.
|
|
|
|
@item qAttached:@var{pid}
|
|
@cindex query attached, remote request
|
|
@cindex @samp{qAttached} packet
|
|
Return an indication of whether the remote server attached to an
|
|
existing process or created a new process. When the multiprocess
|
|
protocol extensions are supported (@pxref{multiprocess extensions}),
|
|
@var{pid} is an integer in hexadecimal format identifying the target
|
|
process. Otherwise, @value{GDBN} will omit the @var{pid} field and
|
|
the query packet will be simplified as @samp{qAttached}.
|
|
|
|
This query is used, for example, to know whether the remote process
|
|
should be detached or killed when a @value{GDBN} session is ended with
|
|
the @code{quit} command.
|
|
|
|
Reply:
|
|
@table @samp
|
|
@item 1
|
|
The remote server attached to an existing process.
|
|
@item 0
|
|
The remote server created a new process.
|
|
@item E @var{NN}
|
|
A badly formed request or an error was encountered.
|
|
@end table
|
|
|
|
@end table
|
|
|
|
@node Architecture-Specific Protocol Details
|
|
@section Architecture-Specific Protocol Details
|
|
|
|
This section describes how the remote protocol is applied to specific
|
|
target architectures. Also see @ref{Standard Target Features}, for
|
|
details of XML target descriptions for each architecture.
|
|
|
|
@menu
|
|
* ARM-Specific Protocol Details::
|
|
* MIPS-Specific Protocol Details::
|
|
@end menu
|
|
|
|
@node ARM-Specific Protocol Details
|
|
@subsection @acronym{ARM}-specific Protocol Details
|
|
|
|
@menu
|
|
* ARM Breakpoint Kinds::
|
|
@end menu
|
|
|
|
@node ARM Breakpoint Kinds
|
|
@subsubsection @acronym{ARM} Breakpoint Kinds
|
|
@cindex breakpoint kinds, @acronym{ARM}
|
|
|
|
These breakpoint kinds are defined for the @samp{Z0} and @samp{Z1} packets.
|
|
|
|
@table @r
|
|
|
|
@item 2
|
|
16-bit Thumb mode breakpoint.
|
|
|
|
@item 3
|
|
32-bit Thumb mode (Thumb-2) breakpoint.
|
|
|
|
@item 4
|
|
32-bit @acronym{ARM} mode breakpoint.
|
|
|
|
@end table
|
|
|
|
@node MIPS-Specific Protocol Details
|
|
@subsection @acronym{MIPS}-specific Protocol Details
|
|
|
|
@menu
|
|
* MIPS Register packet Format::
|
|
* MIPS Breakpoint Kinds::
|
|
@end menu
|
|
|
|
@node MIPS Register packet Format
|
|
@subsubsection @acronym{MIPS} Register Packet Format
|
|
@cindex register packet format, @acronym{MIPS}
|
|
|
|
The following @code{g}/@code{G} packets have previously been defined.
|
|
In the below, some thirty-two bit registers are transferred as
|
|
sixty-four bits. Those registers should be zero/sign extended (which?)
|
|
to fill the space allocated. Register bytes are transferred in target
|
|
byte order. The two nibbles within a register byte are transferred
|
|
most-significant -- least-significant.
|
|
|
|
@table @r
|
|
|
|
@item MIPS32
|
|
All registers are transferred as thirty-two bit quantities in the order:
|
|
32 general-purpose; sr; lo; hi; bad; cause; pc; 32 floating-point
|
|
registers; fsr; fir; fp.
|
|
|
|
@item MIPS64
|
|
All registers are transferred as sixty-four bit quantities (including
|
|
thirty-two bit registers such as @code{sr}). The ordering is the same
|
|
as @code{MIPS32}.
|
|
|
|
@end table
|
|
|
|
@node MIPS Breakpoint Kinds
|
|
@subsubsection @acronym{MIPS} Breakpoint Kinds
|
|
@cindex breakpoint kinds, @acronym{MIPS}
|
|
|
|
These breakpoint kinds are defined for the @samp{Z0} and @samp{Z1} packets.
|
|
|
|
@table @r
|
|
|
|
@item 2
|
|
16-bit @acronym{MIPS16} mode breakpoint.
|
|
|
|
@item 3
|
|
16-bit @acronym{microMIPS} mode breakpoint.
|
|
|
|
@item 4
|
|
32-bit standard @acronym{MIPS} mode breakpoint.
|
|
|
|
@item 5
|
|
32-bit @acronym{microMIPS} mode breakpoint.
|
|
|
|
@end table
|
|
|
|
@node Tracepoint Packets
|
|
@section Tracepoint Packets
|
|
@cindex tracepoint packets
|
|
@cindex packets, tracepoint
|
|
|
|
Here we describe the packets @value{GDBN} uses to implement
|
|
tracepoints (@pxref{Tracepoints}).
|
|
|
|
@table @samp
|
|
|
|
@item QTDP:@var{n}:@var{addr}:@var{ena}:@var{step}:@var{pass}[:F@var{flen}][:X@var{len},@var{bytes}]@r{[}-@r{]}
|
|
@cindex @samp{QTDP} packet
|
|
Create a new tracepoint, number @var{n}, at @var{addr}. If @var{ena}
|
|
is @samp{E}, then the tracepoint is enabled; if it is @samp{D}, then
|
|
the tracepoint is disabled. @var{step} is the tracepoint's step
|
|
count, and @var{pass} is its pass count. If an @samp{F} is present,
|
|
then the tracepoint is to be a fast tracepoint, and the @var{flen} is
|
|
the number of bytes that the target should copy elsewhere to make room
|
|
for the tracepoint. If an @samp{X} is present, it introduces a
|
|
tracepoint condition, which consists of a hexadecimal length, followed
|
|
by a comma and hex-encoded bytes, in a manner similar to action
|
|
encodings as described below. If the trailing @samp{-} is present,
|
|
further @samp{QTDP} packets will follow to specify this tracepoint's
|
|
actions.
|
|
|
|
Replies:
|
|
@table @samp
|
|
@item OK
|
|
The packet was understood and carried out.
|
|
@item qRelocInsn
|
|
@xref{Tracepoint Packets,,Relocate instruction reply packet}.
|
|
@item
|
|
The packet was not recognized.
|
|
@end table
|
|
|
|
@item QTDP:-@var{n}:@var{addr}:@r{[}S@r{]}@var{action}@dots{}@r{[}-@r{]}
|
|
Define actions to be taken when a tracepoint is hit. @var{n} and
|
|
@var{addr} must be the same as in the initial @samp{QTDP} packet for
|
|
this tracepoint. This packet may only be sent immediately after
|
|
another @samp{QTDP} packet that ended with a @samp{-}. If the
|
|
trailing @samp{-} is present, further @samp{QTDP} packets will follow,
|
|
specifying more actions for this tracepoint.
|
|
|
|
In the series of action packets for a given tracepoint, at most one
|
|
can have an @samp{S} before its first @var{action}. If such a packet
|
|
is sent, it and the following packets define ``while-stepping''
|
|
actions. Any prior packets define ordinary actions --- that is, those
|
|
taken when the tracepoint is first hit. If no action packet has an
|
|
@samp{S}, then all the packets in the series specify ordinary
|
|
tracepoint actions.
|
|
|
|
The @samp{@var{action}@dots{}} portion of the packet is a series of
|
|
actions, concatenated without separators. Each action has one of the
|
|
following forms:
|
|
|
|
@table @samp
|
|
|
|
@item R @var{mask}
|
|
Collect the registers whose bits are set in @var{mask}. @var{mask} is
|
|
a hexadecimal number whose @var{i}'th bit is set if register number
|
|
@var{i} should be collected. (The least significant bit is numbered
|
|
zero.) Note that @var{mask} may be any number of digits long; it may
|
|
not fit in a 32-bit word.
|
|
|
|
@item M @var{basereg},@var{offset},@var{len}
|
|
Collect @var{len} bytes of memory starting at the address in register
|
|
number @var{basereg}, plus @var{offset}. If @var{basereg} is
|
|
@samp{-1}, then the range has a fixed address: @var{offset} is the
|
|
address of the lowest byte to collect. The @var{basereg},
|
|
@var{offset}, and @var{len} parameters are all unsigned hexadecimal
|
|
values (the @samp{-1} value for @var{basereg} is a special case).
|
|
|
|
@item X @var{len},@var{expr}
|
|
Evaluate @var{expr}, whose length is @var{len}, and collect memory as
|
|
it directs. @var{expr} is an agent expression, as described in
|
|
@ref{Agent Expressions}. Each byte of the expression is encoded as a
|
|
two-digit hex number in the packet; @var{len} is the number of bytes
|
|
in the expression (and thus one-half the number of hex digits in the
|
|
packet).
|
|
|
|
@end table
|
|
|
|
Any number of actions may be packed together in a single @samp{QTDP}
|
|
packet, as long as the packet does not exceed the maximum packet
|
|
length (400 bytes, for many stubs). There may be only one @samp{R}
|
|
action per tracepoint, and it must precede any @samp{M} or @samp{X}
|
|
actions. Any registers referred to by @samp{M} and @samp{X} actions
|
|
must be collected by a preceding @samp{R} action. (The
|
|
``while-stepping'' actions are treated as if they were attached to a
|
|
separate tracepoint, as far as these restrictions are concerned.)
|
|
|
|
Replies:
|
|
@table @samp
|
|
@item OK
|
|
The packet was understood and carried out.
|
|
@item qRelocInsn
|
|
@xref{Tracepoint Packets,,Relocate instruction reply packet}.
|
|
@item
|
|
The packet was not recognized.
|
|
@end table
|
|
|
|
@item QTDPsrc:@var{n}:@var{addr}:@var{type}:@var{start}:@var{slen}:@var{bytes}
|
|
@cindex @samp{QTDPsrc} packet
|
|
Specify a source string of tracepoint @var{n} at address @var{addr}.
|
|
This is useful to get accurate reproduction of the tracepoints
|
|
originally downloaded at the beginning of the trace run. @var{type}
|
|
is the name of the tracepoint part, such as @samp{cond} for the
|
|
tracepoint's conditional expression (see below for a list of types), while
|
|
@var{bytes} is the string, encoded in hexadecimal.
|
|
|
|
@var{start} is the offset of the @var{bytes} within the overall source
|
|
string, while @var{slen} is the total length of the source string.
|
|
This is intended for handling source strings that are longer than will
|
|
fit in a single packet.
|
|
@c Add detailed example when this info is moved into a dedicated
|
|
@c tracepoint descriptions section.
|
|
|
|
The available string types are @samp{at} for the location,
|
|
@samp{cond} for the conditional, and @samp{cmd} for an action command.
|
|
@value{GDBN} sends a separate packet for each command in the action
|
|
list, in the same order in which the commands are stored in the list.
|
|
|
|
The target does not need to do anything with source strings except
|
|
report them back as part of the replies to the @samp{qTfP}/@samp{qTsP}
|
|
query packets.
|
|
|
|
Although this packet is optional, and @value{GDBN} will only send it
|
|
if the target replies with @samp{TracepointSource} @xref{General
|
|
Query Packets}, it makes both disconnected tracing and trace files
|
|
much easier to use. Otherwise the user must be careful that the
|
|
tracepoints in effect while looking at trace frames are identical to
|
|
the ones in effect during the trace run; even a small discrepancy
|
|
could cause @samp{tdump} not to work, or a particular trace frame not
|
|
be found.
|
|
|
|
@item QTDV:@var{n}:@var{value}
|
|
@cindex define trace state variable, remote request
|
|
@cindex @samp{QTDV} packet
|
|
Create a new trace state variable, number @var{n}, with an initial
|
|
value of @var{value}, which is a 64-bit signed integer. Both @var{n}
|
|
and @var{value} are encoded as hexadecimal values. @value{GDBN} has
|
|
the option of not using this packet for initial values of zero; the
|
|
target should simply create the trace state variables as they are
|
|
mentioned in expressions.
|
|
|
|
@item QTFrame:@var{n}
|
|
@cindex @samp{QTFrame} packet
|
|
Select the @var{n}'th tracepoint frame from the buffer, and use the
|
|
register and memory contents recorded there to answer subsequent
|
|
request packets from @value{GDBN}.
|
|
|
|
A successful reply from the stub indicates that the stub has found the
|
|
requested frame. The response is a series of parts, concatenated
|
|
without separators, describing the frame we selected. Each part has
|
|
one of the following forms:
|
|
|
|
@table @samp
|
|
@item F @var{f}
|
|
The selected frame is number @var{n} in the trace frame buffer;
|
|
@var{f} is a hexadecimal number. If @var{f} is @samp{-1}, then there
|
|
was no frame matching the criteria in the request packet.
|
|
|
|
@item T @var{t}
|
|
The selected trace frame records a hit of tracepoint number @var{t};
|
|
@var{t} is a hexadecimal number.
|
|
|
|
@end table
|
|
|
|
@item QTFrame:pc:@var{addr}
|
|
Like @samp{QTFrame:@var{n}}, but select the first tracepoint frame after the
|
|
currently selected frame whose PC is @var{addr};
|
|
@var{addr} is a hexadecimal number.
|
|
|
|
@item QTFrame:tdp:@var{t}
|
|
Like @samp{QTFrame:@var{n}}, but select the first tracepoint frame after the
|
|
currently selected frame that is a hit of tracepoint @var{t}; @var{t}
|
|
is a hexadecimal number.
|
|
|
|
@item QTFrame:range:@var{start}:@var{end}
|
|
Like @samp{QTFrame:@var{n}}, but select the first tracepoint frame after the
|
|
currently selected frame whose PC is between @var{start} (inclusive)
|
|
and @var{end} (inclusive); @var{start} and @var{end} are hexadecimal
|
|
numbers.
|
|
|
|
@item QTFrame:outside:@var{start}:@var{end}
|
|
Like @samp{QTFrame:range:@var{start}:@var{end}}, but select the first
|
|
frame @emph{outside} the given range of addresses (exclusive).
|
|
|
|
@item qTMinFTPILen
|
|
@cindex @samp{qTMinFTPILen} packet
|
|
This packet requests the minimum length of instruction at which a fast
|
|
tracepoint (@pxref{Set Tracepoints}) may be placed. For instance, on
|
|
the 32-bit x86 architecture, it is possible to use a 4-byte jump, but
|
|
it depends on the target system being able to create trampolines in
|
|
the first 64K of memory, which might or might not be possible for that
|
|
system. So the reply to this packet will be 4 if it is able to
|
|
arrange for that.
|
|
|
|
Replies:
|
|
|
|
@table @samp
|
|
@item 0
|
|
The minimum instruction length is currently unknown.
|
|
@item @var{length}
|
|
The minimum instruction length is @var{length}, where @var{length} is greater
|
|
or equal to 1. @var{length} is a hexadecimal number. A reply of 1 means
|
|
that a fast tracepoint may be placed on any instruction regardless of size.
|
|
@item E
|
|
An error has occurred.
|
|
@item
|
|
An empty reply indicates that the request is not supported by the stub.
|
|
@end table
|
|
|
|
@item QTStart
|
|
@cindex @samp{QTStart} packet
|
|
Begin the tracepoint experiment. Begin collecting data from
|
|
tracepoint hits in the trace frame buffer. This packet supports the
|
|
@samp{qRelocInsn} reply (@pxref{Tracepoint Packets,,Relocate
|
|
instruction reply packet}).
|
|
|
|
@item QTStop
|
|
@cindex @samp{QTStop} packet
|
|
End the tracepoint experiment. Stop collecting trace frames.
|
|
|
|
@item QTEnable:@var{n}:@var{addr}
|
|
@anchor{QTEnable}
|
|
@cindex @samp{QTEnable} packet
|
|
Enable tracepoint @var{n} at address @var{addr} in a started tracepoint
|
|
experiment. If the tracepoint was previously disabled, then collection
|
|
of data from it will resume.
|
|
|
|
@item QTDisable:@var{n}:@var{addr}
|
|
@anchor{QTDisable}
|
|
@cindex @samp{QTDisable} packet
|
|
Disable tracepoint @var{n} at address @var{addr} in a started tracepoint
|
|
experiment. No more data will be collected from the tracepoint unless
|
|
@samp{QTEnable:@var{n}:@var{addr}} is subsequently issued.
|
|
|
|
@item QTinit
|
|
@cindex @samp{QTinit} packet
|
|
Clear the table of tracepoints, and empty the trace frame buffer.
|
|
|
|
@item QTro:@var{start1},@var{end1}:@var{start2},@var{end2}:@dots{}
|
|
@cindex @samp{QTro} packet
|
|
Establish the given ranges of memory as ``transparent''. The stub
|
|
will answer requests for these ranges from memory's current contents,
|
|
if they were not collected as part of the tracepoint hit.
|
|
|
|
@value{GDBN} uses this to mark read-only regions of memory, like those
|
|
containing program code. Since these areas never change, they should
|
|
still have the same contents they did when the tracepoint was hit, so
|
|
there's no reason for the stub to refuse to provide their contents.
|
|
|
|
@item QTDisconnected:@var{value}
|
|
@cindex @samp{QTDisconnected} packet
|
|
Set the choice to what to do with the tracing run when @value{GDBN}
|
|
disconnects from the target. A @var{value} of 1 directs the target to
|
|
continue the tracing run, while 0 tells the target to stop tracing if
|
|
@value{GDBN} is no longer in the picture.
|
|
|
|
@item qTStatus
|
|
@cindex @samp{qTStatus} packet
|
|
Ask the stub if there is a trace experiment running right now.
|
|
|
|
The reply has the form:
|
|
|
|
@table @samp
|
|
|
|
@item T@var{running}@r{[};@var{field}@r{]}@dots{}
|
|
@var{running} is a single digit @code{1} if the trace is presently
|
|
running, or @code{0} if not. It is followed by semicolon-separated
|
|
optional fields that an agent may use to report additional status.
|
|
|
|
@end table
|
|
|
|
If the trace is not running, the agent may report any of several
|
|
explanations as one of the optional fields:
|
|
|
|
@table @samp
|
|
|
|
@item tnotrun:0
|
|
No trace has been run yet.
|
|
|
|
@item tstop[:@var{text}]:0
|
|
The trace was stopped by a user-originated stop command. The optional
|
|
@var{text} field is a user-supplied string supplied as part of the
|
|
stop command (for instance, an explanation of why the trace was
|
|
stopped manually). It is hex-encoded.
|
|
|
|
@item tfull:0
|
|
The trace stopped because the trace buffer filled up.
|
|
|
|
@item tdisconnected:0
|
|
The trace stopped because @value{GDBN} disconnected from the target.
|
|
|
|
@item tpasscount:@var{tpnum}
|
|
The trace stopped because tracepoint @var{tpnum} exceeded its pass count.
|
|
|
|
@item terror:@var{text}:@var{tpnum}
|
|
The trace stopped because tracepoint @var{tpnum} had an error. The
|
|
string @var{text} is available to describe the nature of the error
|
|
(for instance, a divide by zero in the condition expression).
|
|
@var{text} is hex encoded.
|
|
|
|
@item tunknown:0
|
|
The trace stopped for some other reason.
|
|
|
|
@end table
|
|
|
|
Additional optional fields supply statistical and other information.
|
|
Although not required, they are extremely useful for users monitoring
|
|
the progress of a trace run. If a trace has stopped, and these
|
|
numbers are reported, they must reflect the state of the just-stopped
|
|
trace.
|
|
|
|
@table @samp
|
|
|
|
@item tframes:@var{n}
|
|
The number of trace frames in the buffer.
|
|
|
|
@item tcreated:@var{n}
|
|
The total number of trace frames created during the run. This may
|
|
be larger than the trace frame count, if the buffer is circular.
|
|
|
|
@item tsize:@var{n}
|
|
The total size of the trace buffer, in bytes.
|
|
|
|
@item tfree:@var{n}
|
|
The number of bytes still unused in the buffer.
|
|
|
|
@item circular:@var{n}
|
|
The value of the circular trace buffer flag. @code{1} means that the
|
|
trace buffer is circular and old trace frames will be discarded if
|
|
necessary to make room, @code{0} means that the trace buffer is linear
|
|
and may fill up.
|
|
|
|
@item disconn:@var{n}
|
|
The value of the disconnected tracing flag. @code{1} means that
|
|
tracing will continue after @value{GDBN} disconnects, @code{0} means
|
|
that the trace run will stop.
|
|
|
|
@end table
|
|
|
|
@item qTP:@var{tp}:@var{addr}
|
|
@cindex tracepoint status, remote request
|
|
@cindex @samp{qTP} packet
|
|
Ask the stub for the current state of tracepoint number @var{tp} at
|
|
address @var{addr}.
|
|
|
|
Replies:
|
|
@table @samp
|
|
@item V@var{hits}:@var{usage}
|
|
The tracepoint has been hit @var{hits} times so far during the trace
|
|
run, and accounts for @var{usage} in the trace buffer. Note that
|
|
@code{while-stepping} steps are not counted as separate hits, but the
|
|
steps' space consumption is added into the usage number.
|
|
|
|
@end table
|
|
|
|
@item qTV:@var{var}
|
|
@cindex trace state variable value, remote request
|
|
@cindex @samp{qTV} packet
|
|
Ask the stub for the value of the trace state variable number @var{var}.
|
|
|
|
Replies:
|
|
@table @samp
|
|
@item V@var{value}
|
|
The value of the variable is @var{value}. This will be the current
|
|
value of the variable if the user is examining a running target, or a
|
|
saved value if the variable was collected in the trace frame that the
|
|
user is looking at. Note that multiple requests may result in
|
|
different reply values, such as when requesting values while the
|
|
program is running.
|
|
|
|
@item U
|
|
The value of the variable is unknown. This would occur, for example,
|
|
if the user is examining a trace frame in which the requested variable
|
|
was not collected.
|
|
@end table
|
|
|
|
@item qTfP
|
|
@cindex @samp{qTfP} packet
|
|
@itemx qTsP
|
|
@cindex @samp{qTsP} packet
|
|
These packets request data about tracepoints that are being used by
|
|
the target. @value{GDBN} sends @code{qTfP} to get the first piece
|
|
of data, and multiple @code{qTsP} to get additional pieces. Replies
|
|
to these packets generally take the form of the @code{QTDP} packets
|
|
that define tracepoints. (FIXME add detailed syntax)
|
|
|
|
@item qTfV
|
|
@cindex @samp{qTfV} packet
|
|
@itemx qTsV
|
|
@cindex @samp{qTsV} packet
|
|
These packets request data about trace state variables that are on the
|
|
target. @value{GDBN} sends @code{qTfV} to get the first vari of data,
|
|
and multiple @code{qTsV} to get additional variables. Replies to
|
|
these packets follow the syntax of the @code{QTDV} packets that define
|
|
trace state variables.
|
|
|
|
@item qTfSTM
|
|
@itemx qTsSTM
|
|
@anchor{qTfSTM}
|
|
@anchor{qTsSTM}
|
|
@cindex @samp{qTfSTM} packet
|
|
@cindex @samp{qTsSTM} packet
|
|
These packets request data about static tracepoint markers that exist
|
|
in the target program. @value{GDBN} sends @code{qTfSTM} to get the
|
|
first piece of data, and multiple @code{qTsSTM} to get additional
|
|
pieces. Replies to these packets take the following form:
|
|
|
|
Reply:
|
|
@table @samp
|
|
@item m @var{address}:@var{id}:@var{extra}
|
|
A single marker
|
|
@item m @var{address}:@var{id}:@var{extra},@var{address}:@var{id}:@var{extra}@dots{}
|
|
a comma-separated list of markers
|
|
@item l
|
|
(lower case letter @samp{L}) denotes end of list.
|
|
@item E @var{nn}
|
|
An error occurred. @var{nn} are hex digits.
|
|
@item
|
|
An empty reply indicates that the request is not supported by the
|
|
stub.
|
|
@end table
|
|
|
|
@var{address} is encoded in hex.
|
|
@var{id} and @var{extra} are strings encoded in hex.
|
|
|
|
In response to each query, the target will reply with a list of one or
|
|
more markers, separated by commas. @value{GDBN} will respond to each
|
|
reply with a request for more markers (using the @samp{qs} form of the
|
|
query), until the target responds with @samp{l} (lower-case ell, for
|
|
@dfn{last}).
|
|
|
|
@item qTSTMat:@var{address}
|
|
@anchor{qTSTMat}
|
|
@cindex @samp{qTSTMat} packet
|
|
This packets requests data about static tracepoint markers in the
|
|
target program at @var{address}. Replies to this packet follow the
|
|
syntax of the @samp{qTfSTM} and @code{qTsSTM} packets that list static
|
|
tracepoint markers.
|
|
|
|
@item QTSave:@var{filename}
|
|
@cindex @samp{QTSave} packet
|
|
This packet directs the target to save trace data to the file name
|
|
@var{filename} in the target's filesystem. @var{filename} is encoded
|
|
as a hex string; the interpretation of the file name (relative vs
|
|
absolute, wild cards, etc) is up to the target.
|
|
|
|
@item qTBuffer:@var{offset},@var{len}
|
|
@cindex @samp{qTBuffer} packet
|
|
Return up to @var{len} bytes of the current contents of trace buffer,
|
|
starting at @var{offset}. The trace buffer is treated as if it were
|
|
a contiguous collection of traceframes, as per the trace file format.
|
|
The reply consists as many hex-encoded bytes as the target can deliver
|
|
in a packet; it is not an error to return fewer than were asked for.
|
|
A reply consisting of just @code{l} indicates that no bytes are
|
|
available.
|
|
|
|
@item QTBuffer:circular:@var{value}
|
|
This packet directs the target to use a circular trace buffer if
|
|
@var{value} is 1, or a linear buffer if the value is 0.
|
|
|
|
@item QTNotes:@r{[}@var{type}:@var{text}@r{]}@r{[};@var{type}:@var{text}@r{]}@dots{}
|
|
@cindex @samp{QTNotes} packet
|
|
This packet adds optional textual notes to the trace run. Allowable
|
|
types include @code{user}, @code{notes}, and @code{tstop}, the
|
|
@var{text} fields are arbitrary strings, hex-encoded.
|
|
|
|
@end table
|
|
|
|
@subsection Relocate instruction reply packet
|
|
When installing fast tracepoints in memory, the target may need to
|
|
relocate the instruction currently at the tracepoint address to a
|
|
different address in memory. For most instructions, a simple copy is
|
|
enough, but, for example, call instructions that implicitly push the
|
|
return address on the stack, and relative branches or other
|
|
PC-relative instructions require offset adjustment, so that the effect
|
|
of executing the instruction at a different address is the same as if
|
|
it had executed in the original location.
|
|
|
|
In response to several of the tracepoint packets, the target may also
|
|
respond with a number of intermediate @samp{qRelocInsn} request
|
|
packets before the final result packet, to have @value{GDBN} handle
|
|
this relocation operation. If a packet supports this mechanism, its
|
|
documentation will explicitly say so. See for example the above
|
|
descriptions for the @samp{QTStart} and @samp{QTDP} packets. The
|
|
format of the request is:
|
|
|
|
@table @samp
|
|
@item qRelocInsn:@var{from};@var{to}
|
|
|
|
This requests @value{GDBN} to copy instruction at address @var{from}
|
|
to address @var{to}, possibly adjusted so that executing the
|
|
instruction at @var{to} has the same effect as executing it at
|
|
@var{from}. @value{GDBN} writes the adjusted instruction to target
|
|
memory starting at @var{to}.
|
|
@end table
|
|
|
|
Replies:
|
|
@table @samp
|
|
@item qRelocInsn:@var{adjusted_size}
|
|
Informs the stub the relocation is complete. @var{adjusted_size} is
|
|
the length in bytes of resulting relocated instruction sequence.
|
|
@item E @var{NN}
|
|
A badly formed request was detected, or an error was encountered while
|
|
relocating the instruction.
|
|
@end table
|
|
|
|
@node Host I/O Packets
|
|
@section Host I/O Packets
|
|
@cindex Host I/O, remote protocol
|
|
@cindex file transfer, remote protocol
|
|
|
|
The @dfn{Host I/O} packets allow @value{GDBN} to perform I/O
|
|
operations on the far side of a remote link. For example, Host I/O is
|
|
used to upload and download files to a remote target with its own
|
|
filesystem. Host I/O uses the same constant values and data structure
|
|
layout as the target-initiated File-I/O protocol. However, the
|
|
Host I/O packets are structured differently. The target-initiated
|
|
protocol relies on target memory to store parameters and buffers.
|
|
Host I/O requests are initiated by @value{GDBN}, and the
|
|
target's memory is not involved. @xref{File-I/O Remote Protocol
|
|
Extension}, for more details on the target-initiated protocol.
|
|
|
|
The Host I/O request packets all encode a single operation along with
|
|
its arguments. They have this format:
|
|
|
|
@table @samp
|
|
|
|
@item vFile:@var{operation}: @var{parameter}@dots{}
|
|
@var{operation} is the name of the particular request; the target
|
|
should compare the entire packet name up to the second colon when checking
|
|
for a supported operation. The format of @var{parameter} depends on
|
|
the operation. Numbers are always passed in hexadecimal. Negative
|
|
numbers have an explicit minus sign (i.e.@: two's complement is not
|
|
used). Strings (e.g.@: filenames) are encoded as a series of
|
|
hexadecimal bytes. The last argument to a system call may be a
|
|
buffer of escaped binary data (@pxref{Binary Data}).
|
|
|
|
@end table
|
|
|
|
The valid responses to Host I/O packets are:
|
|
|
|
@table @samp
|
|
|
|
@item F @var{result} [, @var{errno}] [; @var{attachment}]
|
|
@var{result} is the integer value returned by this operation, usually
|
|
non-negative for success and -1 for errors. If an error has occured,
|
|
@var{errno} will be included in the result. @var{errno} will have a
|
|
value defined by the File-I/O protocol (@pxref{Errno Values}). For
|
|
operations which return data, @var{attachment} supplies the data as a
|
|
binary buffer. Binary buffers in response packets are escaped in the
|
|
normal way (@pxref{Binary Data}). See the individual packet
|
|
documentation for the interpretation of @var{result} and
|
|
@var{attachment}.
|
|
|
|
@item
|
|
An empty response indicates that this operation is not recognized.
|
|
|
|
@end table
|
|
|
|
These are the supported Host I/O operations:
|
|
|
|
@table @samp
|
|
@item vFile:open: @var{pathname}, @var{flags}, @var{mode}
|
|
Open a file at @var{pathname} and return a file descriptor for it, or
|
|
return -1 if an error occurs. @var{pathname} is a string,
|
|
@var{flags} is an integer indicating a mask of open flags
|
|
(@pxref{Open Flags}), and @var{mode} is an integer indicating a mask
|
|
of mode bits to use if the file is created (@pxref{mode_t Values}).
|
|
@xref{open}, for details of the open flags and mode values.
|
|
|
|
@item vFile:close: @var{fd}
|
|
Close the open file corresponding to @var{fd} and return 0, or
|
|
-1 if an error occurs.
|
|
|
|
@item vFile:pread: @var{fd}, @var{count}, @var{offset}
|
|
Read data from the open file corresponding to @var{fd}. Up to
|
|
@var{count} bytes will be read from the file, starting at @var{offset}
|
|
relative to the start of the file. The target may read fewer bytes;
|
|
common reasons include packet size limits and an end-of-file
|
|
condition. The number of bytes read is returned. Zero should only be
|
|
returned for a successful read at the end of the file, or if
|
|
@var{count} was zero.
|
|
|
|
The data read should be returned as a binary attachment on success.
|
|
If zero bytes were read, the response should include an empty binary
|
|
attachment (i.e.@: a trailing semicolon). The return value is the
|
|
number of target bytes read; the binary attachment may be longer if
|
|
some characters were escaped.
|
|
|
|
@item vFile:pwrite: @var{fd}, @var{offset}, @var{data}
|
|
Write @var{data} (a binary buffer) to the open file corresponding
|
|
to @var{fd}. Start the write at @var{offset} from the start of the
|
|
file. Unlike many @code{write} system calls, there is no
|
|
separate @var{count} argument; the length of @var{data} in the
|
|
packet is used. @samp{vFile:write} returns the number of bytes written,
|
|
which may be shorter than the length of @var{data}, or -1 if an
|
|
error occurred.
|
|
|
|
@item vFile:unlink: @var{pathname}
|
|
Delete the file at @var{pathname} on the target. Return 0,
|
|
or -1 if an error occurs. @var{pathname} is a string.
|
|
|
|
@item vFile:readlink: @var{filename}
|
|
Read value of symbolic link @var{filename} on the target. Return
|
|
the number of bytes read, or -1 if an error occurs.
|
|
|
|
The data read should be returned as a binary attachment on success.
|
|
If zero bytes were read, the response should include an empty binary
|
|
attachment (i.e.@: a trailing semicolon). The return value is the
|
|
number of target bytes read; the binary attachment may be longer if
|
|
some characters were escaped.
|
|
|
|
@end table
|
|
|
|
@node Interrupts
|
|
@section Interrupts
|
|
@cindex interrupts (remote protocol)
|
|
|
|
When a program on the remote target is running, @value{GDBN} may
|
|
attempt to interrupt it by sending a @samp{Ctrl-C}, @code{BREAK} or
|
|
a @code{BREAK} followed by @code{g},
|
|
control of which is specified via @value{GDBN}'s @samp{interrupt-sequence}.
|
|
|
|
The precise meaning of @code{BREAK} is defined by the transport
|
|
mechanism and may, in fact, be undefined. @value{GDBN} does not
|
|
currently define a @code{BREAK} mechanism for any of the network
|
|
interfaces except for TCP, in which case @value{GDBN} sends the
|
|
@code{telnet} BREAK sequence.
|
|
|
|
@samp{Ctrl-C}, on the other hand, is defined and implemented for all
|
|
transport mechanisms. It is represented by sending the single byte
|
|
@code{0x03} without any of the usual packet overhead described in
|
|
the Overview section (@pxref{Overview}). When a @code{0x03} byte is
|
|
transmitted as part of a packet, it is considered to be packet data
|
|
and does @emph{not} represent an interrupt. E.g., an @samp{X} packet
|
|
(@pxref{X packet}), used for binary downloads, may include an unescaped
|
|
@code{0x03} as part of its packet.
|
|
|
|
@code{BREAK} followed by @code{g} is also known as Magic SysRq g.
|
|
When Linux kernel receives this sequence from serial port,
|
|
it stops execution and connects to gdb.
|
|
|
|
Stubs are not required to recognize these interrupt mechanisms and the
|
|
precise meaning associated with receipt of the interrupt is
|
|
implementation defined. If the target supports debugging of multiple
|
|
threads and/or processes, it should attempt to interrupt all
|
|
currently-executing threads and processes.
|
|
If the stub is successful at interrupting the
|
|
running program, it should send one of the stop
|
|
reply packets (@pxref{Stop Reply Packets}) to @value{GDBN} as a result
|
|
of successfully stopping the program in all-stop mode, and a stop reply
|
|
for each stopped thread in non-stop mode.
|
|
Interrupts received while the
|
|
program is stopped are discarded.
|
|
|
|
@node Notification Packets
|
|
@section Notification Packets
|
|
@cindex notification packets
|
|
@cindex packets, notification
|
|
|
|
The @value{GDBN} remote serial protocol includes @dfn{notifications},
|
|
packets that require no acknowledgment. Both the GDB and the stub
|
|
may send notifications (although the only notifications defined at
|
|
present are sent by the stub). Notifications carry information
|
|
without incurring the round-trip latency of an acknowledgment, and so
|
|
are useful for low-impact communications where occasional packet loss
|
|
is not a problem.
|
|
|
|
A notification packet has the form @samp{% @var{data} #
|
|
@var{checksum}}, where @var{data} is the content of the notification,
|
|
and @var{checksum} is a checksum of @var{data}, computed and formatted
|
|
as for ordinary @value{GDBN} packets. A notification's @var{data}
|
|
never contains @samp{$}, @samp{%} or @samp{#} characters. Upon
|
|
receiving a notification, the recipient sends no @samp{+} or @samp{-}
|
|
to acknowledge the notification's receipt or to report its corruption.
|
|
|
|
Every notification's @var{data} begins with a name, which contains no
|
|
colon characters, followed by a colon character.
|
|
|
|
Recipients should silently ignore corrupted notifications and
|
|
notifications they do not understand. Recipients should restart
|
|
timeout periods on receipt of a well-formed notification, whether or
|
|
not they understand it.
|
|
|
|
Senders should only send the notifications described here when this
|
|
protocol description specifies that they are permitted. In the
|
|
future, we may extend the protocol to permit existing notifications in
|
|
new contexts; this rule helps older senders avoid confusing newer
|
|
recipients.
|
|
|
|
(Older versions of @value{GDBN} ignore bytes received until they see
|
|
the @samp{$} byte that begins an ordinary packet, so new stubs may
|
|
transmit notifications without fear of confusing older clients. There
|
|
are no notifications defined for @value{GDBN} to send at the moment, but we
|
|
assume that most older stubs would ignore them, as well.)
|
|
|
|
The following notification packets from the stub to @value{GDBN} are
|
|
defined:
|
|
|
|
@table @samp
|
|
@item Stop: @var{reply}
|
|
Report an asynchronous stop event in non-stop mode.
|
|
The @var{reply} has the form of a stop reply, as
|
|
described in @ref{Stop Reply Packets}. Refer to @ref{Remote Non-Stop},
|
|
for information on how these notifications are acknowledged by
|
|
@value{GDBN}.
|
|
@end table
|
|
|
|
@node Remote Non-Stop
|
|
@section Remote Protocol Support for Non-Stop Mode
|
|
|
|
@value{GDBN}'s remote protocol supports non-stop debugging of
|
|
multi-threaded programs, as described in @ref{Non-Stop Mode}. If the stub
|
|
supports non-stop mode, it should report that to @value{GDBN} by including
|
|
@samp{QNonStop+} in its @samp{qSupported} response (@pxref{qSupported}).
|
|
|
|
@value{GDBN} typically sends a @samp{QNonStop} packet only when
|
|
establishing a new connection with the stub. Entering non-stop mode
|
|
does not alter the state of any currently-running threads, but targets
|
|
must stop all threads in any already-attached processes when entering
|
|
all-stop mode. @value{GDBN} uses the @samp{?} packet as necessary to
|
|
probe the target state after a mode change.
|
|
|
|
In non-stop mode, when an attached process encounters an event that
|
|
would otherwise be reported with a stop reply, it uses the
|
|
asynchronous notification mechanism (@pxref{Notification Packets}) to
|
|
inform @value{GDBN}. In contrast to all-stop mode, where all threads
|
|
in all processes are stopped when a stop reply is sent, in non-stop
|
|
mode only the thread reporting the stop event is stopped. That is,
|
|
when reporting a @samp{S} or @samp{T} response to indicate completion
|
|
of a step operation, hitting a breakpoint, or a fault, only the
|
|
affected thread is stopped; any other still-running threads continue
|
|
to run. When reporting a @samp{W} or @samp{X} response, all running
|
|
threads belonging to other attached processes continue to run.
|
|
|
|
Only one stop reply notification at a time may be pending; if
|
|
additional stop events occur before @value{GDBN} has acknowledged the
|
|
previous notification, they must be queued by the stub for later
|
|
synchronous transmission in response to @samp{vStopped} packets from
|
|
@value{GDBN}. Because the notification mechanism is unreliable,
|
|
the stub is permitted to resend a stop reply notification
|
|
if it believes @value{GDBN} may not have received it. @value{GDBN}
|
|
ignores additional stop reply notifications received before it has
|
|
finished processing a previous notification and the stub has completed
|
|
sending any queued stop events.
|
|
|
|
Otherwise, @value{GDBN} must be prepared to receive a stop reply
|
|
notification at any time. Specifically, they may appear when
|
|
@value{GDBN} is not otherwise reading input from the stub, or when
|
|
@value{GDBN} is expecting to read a normal synchronous response or a
|
|
@samp{+}/@samp{-} acknowledgment to a packet it has sent.
|
|
Notification packets are distinct from any other communication from
|
|
the stub so there is no ambiguity.
|
|
|
|
After receiving a stop reply notification, @value{GDBN} shall
|
|
acknowledge it by sending a @samp{vStopped} packet (@pxref{vStopped packet})
|
|
as a regular, synchronous request to the stub. Such acknowledgment
|
|
is not required to happen immediately, as @value{GDBN} is permitted to
|
|
send other, unrelated packets to the stub first, which the stub should
|
|
process normally.
|
|
|
|
Upon receiving a @samp{vStopped} packet, if the stub has other queued
|
|
stop events to report to @value{GDBN}, it shall respond by sending a
|
|
normal stop reply response. @value{GDBN} shall then send another
|
|
@samp{vStopped} packet to solicit further responses; again, it is
|
|
permitted to send other, unrelated packets as well which the stub
|
|
should process normally.
|
|
|
|
If the stub receives a @samp{vStopped} packet and there are no
|
|
additional stop events to report, the stub shall return an @samp{OK}
|
|
response. At this point, if further stop events occur, the stub shall
|
|
send a new stop reply notification, @value{GDBN} shall accept the
|
|
notification, and the process shall be repeated.
|
|
|
|
In non-stop mode, the target shall respond to the @samp{?} packet as
|
|
follows. First, any incomplete stop reply notification/@samp{vStopped}
|
|
sequence in progress is abandoned. The target must begin a new
|
|
sequence reporting stop events for all stopped threads, whether or not
|
|
it has previously reported those events to @value{GDBN}. The first
|
|
stop reply is sent as a synchronous reply to the @samp{?} packet, and
|
|
subsequent stop replies are sent as responses to @samp{vStopped} packets
|
|
using the mechanism described above. The target must not send
|
|
asynchronous stop reply notifications until the sequence is complete.
|
|
If all threads are running when the target receives the @samp{?} packet,
|
|
or if the target is not attached to any process, it shall respond
|
|
@samp{OK}.
|
|
|
|
@node Packet Acknowledgment
|
|
@section Packet Acknowledgment
|
|
|
|
@cindex acknowledgment, for @value{GDBN} remote
|
|
@cindex packet acknowledgment, for @value{GDBN} remote
|
|
By default, when either the host or the target machine receives a packet,
|
|
the first response expected is an acknowledgment: either @samp{+} (to indicate
|
|
the package was received correctly) or @samp{-} (to request retransmission).
|
|
This mechanism allows the @value{GDBN} remote protocol to operate over
|
|
unreliable transport mechanisms, such as a serial line.
|
|
|
|
In cases where the transport mechanism is itself reliable (such as a pipe or
|
|
TCP connection), the @samp{+}/@samp{-} acknowledgments are redundant.
|
|
It may be desirable to disable them in that case to reduce communication
|
|
overhead, or for other reasons. This can be accomplished by means of the
|
|
@samp{QStartNoAckMode} packet; @pxref{QStartNoAckMode}.
|
|
|
|
When in no-acknowledgment mode, neither the stub nor @value{GDBN} shall send or
|
|
expect @samp{+}/@samp{-} protocol acknowledgments. The packet
|
|
and response format still includes the normal checksum, as described in
|
|
@ref{Overview}, but the checksum may be ignored by the receiver.
|
|
|
|
If the stub supports @samp{QStartNoAckMode} and prefers to operate in
|
|
no-acknowledgment mode, it should report that to @value{GDBN}
|
|
by including @samp{QStartNoAckMode+} in its response to @samp{qSupported};
|
|
@pxref{qSupported}.
|
|
If @value{GDBN} also supports @samp{QStartNoAckMode} and it has not been
|
|
disabled via the @code{set remote noack-packet off} command
|
|
(@pxref{Remote Configuration}),
|
|
@value{GDBN} may then send a @samp{QStartNoAckMode} packet to the stub.
|
|
Only then may the stub actually turn off packet acknowledgments.
|
|
@value{GDBN} sends a final @samp{+} acknowledgment of the stub's @samp{OK}
|
|
response, which can be safely ignored by the stub.
|
|
|
|
Note that @code{set remote noack-packet} command only affects negotiation
|
|
between @value{GDBN} and the stub when subsequent connections are made;
|
|
it does not affect the protocol acknowledgment state for any current
|
|
connection.
|
|
Since @samp{+}/@samp{-} acknowledgments are enabled by default when a
|
|
new connection is established,
|
|
there is also no protocol request to re-enable the acknowledgments
|
|
for the current connection, once disabled.
|
|
|
|
@node Examples
|
|
@section Examples
|
|
|
|
Example sequence of a target being re-started. Notice how the restart
|
|
does not get any direct output:
|
|
|
|
@smallexample
|
|
-> @code{R00}
|
|
<- @code{+}
|
|
@emph{target restarts}
|
|
-> @code{?}
|
|
<- @code{+}
|
|
<- @code{T001:1234123412341234}
|
|
-> @code{+}
|
|
@end smallexample
|
|
|
|
Example sequence of a target being stepped by a single instruction:
|
|
|
|
@smallexample
|
|
-> @code{G1445@dots{}}
|
|
<- @code{+}
|
|
-> @code{s}
|
|
<- @code{+}
|
|
@emph{time passes}
|
|
<- @code{T001:1234123412341234}
|
|
-> @code{+}
|
|
-> @code{g}
|
|
<- @code{+}
|
|
<- @code{1455@dots{}}
|
|
-> @code{+}
|
|
@end smallexample
|
|
|
|
@node File-I/O Remote Protocol Extension
|
|
@section File-I/O Remote Protocol Extension
|
|
@cindex File-I/O remote protocol extension
|
|
|
|
@menu
|
|
* File-I/O Overview::
|
|
* Protocol Basics::
|
|
* The F Request Packet::
|
|
* The F Reply Packet::
|
|
* The Ctrl-C Message::
|
|
* Console I/O::
|
|
* List of Supported Calls::
|
|
* Protocol-specific Representation of Datatypes::
|
|
* Constants::
|
|
* File-I/O Examples::
|
|
@end menu
|
|
|
|
@node File-I/O Overview
|
|
@subsection File-I/O Overview
|
|
@cindex file-i/o overview
|
|
|
|
The @dfn{File I/O remote protocol extension} (short: File-I/O) allows the
|
|
target to use the host's file system and console I/O to perform various
|
|
system calls. System calls on the target system are translated into a
|
|
remote protocol packet to the host system, which then performs the needed
|
|
actions and returns a response packet to the target system.
|
|
This simulates file system operations even on targets that lack file systems.
|
|
|
|
The protocol is defined to be independent of both the host and target systems.
|
|
It uses its own internal representation of datatypes and values. Both
|
|
@value{GDBN} and the target's @value{GDBN} stub are responsible for
|
|
translating the system-dependent value representations into the internal
|
|
protocol representations when data is transmitted.
|
|
|
|
The communication is synchronous. A system call is possible only when
|
|
@value{GDBN} is waiting for a response from the @samp{C}, @samp{c}, @samp{S}
|
|
or @samp{s} packets. While @value{GDBN} handles the request for a system call,
|
|
the target is stopped to allow deterministic access to the target's
|
|
memory. Therefore File-I/O is not interruptible by target signals. On
|
|
the other hand, it is possible to interrupt File-I/O by a user interrupt
|
|
(@samp{Ctrl-C}) within @value{GDBN}.
|
|
|
|
The target's request to perform a host system call does not finish
|
|
the latest @samp{C}, @samp{c}, @samp{S} or @samp{s} action. That means,
|
|
after finishing the system call, the target returns to continuing the
|
|
previous activity (continue, step). No additional continue or step
|
|
request from @value{GDBN} is required.
|
|
|
|
@smallexample
|
|
(@value{GDBP}) continue
|
|
<- target requests 'system call X'
|
|
target is stopped, @value{GDBN} executes system call
|
|
-> @value{GDBN} returns result
|
|
... target continues, @value{GDBN} returns to wait for the target
|
|
<- target hits breakpoint and sends a Txx packet
|
|
@end smallexample
|
|
|
|
The protocol only supports I/O on the console and to regular files on
|
|
the host file system. Character or block special devices, pipes,
|
|
named pipes, sockets or any other communication method on the host
|
|
system are not supported by this protocol.
|
|
|
|
File I/O is not supported in non-stop mode.
|
|
|
|
@node Protocol Basics
|
|
@subsection Protocol Basics
|
|
@cindex protocol basics, file-i/o
|
|
|
|
The File-I/O protocol uses the @code{F} packet as the request as well
|
|
as reply packet. Since a File-I/O system call can only occur when
|
|
@value{GDBN} is waiting for a response from the continuing or stepping target,
|
|
the File-I/O request is a reply that @value{GDBN} has to expect as a result
|
|
of a previous @samp{C}, @samp{c}, @samp{S} or @samp{s} packet.
|
|
This @code{F} packet contains all information needed to allow @value{GDBN}
|
|
to call the appropriate host system call:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
A unique identifier for the requested system call.
|
|
|
|
@item
|
|
All parameters to the system call. Pointers are given as addresses
|
|
in the target memory address space. Pointers to strings are given as
|
|
pointer/length pair. Numerical values are given as they are.
|
|
Numerical control flags are given in a protocol-specific representation.
|
|
|
|
@end itemize
|
|
|
|
At this point, @value{GDBN} has to perform the following actions.
|
|
|
|
@itemize @bullet
|
|
@item
|
|
If the parameters include pointer values to data needed as input to a
|
|
system call, @value{GDBN} requests this data from the target with a
|
|
standard @code{m} packet request. This additional communication has to be
|
|
expected by the target implementation and is handled as any other @code{m}
|
|
packet.
|
|
|
|
@item
|
|
@value{GDBN} translates all value from protocol representation to host
|
|
representation as needed. Datatypes are coerced into the host types.
|
|
|
|
@item
|
|
@value{GDBN} calls the system call.
|
|
|
|
@item
|
|
It then coerces datatypes back to protocol representation.
|
|
|
|
@item
|
|
If the system call is expected to return data in buffer space specified
|
|
by pointer parameters to the call, the data is transmitted to the
|
|
target using a @code{M} or @code{X} packet. This packet has to be expected
|
|
by the target implementation and is handled as any other @code{M} or @code{X}
|
|
packet.
|
|
|
|
@end itemize
|
|
|
|
Eventually @value{GDBN} replies with another @code{F} packet which contains all
|
|
necessary information for the target to continue. This at least contains
|
|
|
|
@itemize @bullet
|
|
@item
|
|
Return value.
|
|
|
|
@item
|
|
@code{errno}, if has been changed by the system call.
|
|
|
|
@item
|
|
``Ctrl-C'' flag.
|
|
|
|
@end itemize
|
|
|
|
After having done the needed type and value coercion, the target continues
|
|
the latest continue or step action.
|
|
|
|
@node The F Request Packet
|
|
@subsection The @code{F} Request Packet
|
|
@cindex file-i/o request packet
|
|
@cindex @code{F} request packet
|
|
|
|
The @code{F} request packet has the following format:
|
|
|
|
@table @samp
|
|
@item F@var{call-id},@var{parameter@dots{}}
|
|
|
|
@var{call-id} is the identifier to indicate the host system call to be called.
|
|
This is just the name of the function.
|
|
|
|
@var{parameter@dots{}} are the parameters to the system call.
|
|
Parameters are hexadecimal integer values, either the actual values in case
|
|
of scalar datatypes, pointers to target buffer space in case of compound
|
|
datatypes and unspecified memory areas, or pointer/length pairs in case
|
|
of string parameters. These are appended to the @var{call-id} as a
|
|
comma-delimited list. All values are transmitted in ASCII
|
|
string representation, pointer/length pairs separated by a slash.
|
|
|
|
@end table
|
|
|
|
|
|
|
|
@node The F Reply Packet
|
|
@subsection The @code{F} Reply Packet
|
|
@cindex file-i/o reply packet
|
|
@cindex @code{F} reply packet
|
|
|
|
The @code{F} reply packet has the following format:
|
|
|
|
@table @samp
|
|
|
|
@item F@var{retcode},@var{errno},@var{Ctrl-C flag};@var{call-specific attachment}
|
|
|
|
@var{retcode} is the return code of the system call as hexadecimal value.
|
|
|
|
@var{errno} is the @code{errno} set by the call, in protocol-specific
|
|
representation.
|
|
This parameter can be omitted if the call was successful.
|
|
|
|
@var{Ctrl-C flag} is only sent if the user requested a break. In this
|
|
case, @var{errno} must be sent as well, even if the call was successful.
|
|
The @var{Ctrl-C flag} itself consists of the character @samp{C}:
|
|
|
|
@smallexample
|
|
F0,0,C
|
|
@end smallexample
|
|
|
|
@noindent
|
|
or, if the call was interrupted before the host call has been performed:
|
|
|
|
@smallexample
|
|
F-1,4,C
|
|
@end smallexample
|
|
|
|
@noindent
|
|
assuming 4 is the protocol-specific representation of @code{EINTR}.
|
|
|
|
@end table
|
|
|
|
|
|
@node The Ctrl-C Message
|
|
@subsection The @samp{Ctrl-C} Message
|
|
@cindex ctrl-c message, in file-i/o protocol
|
|
|
|
If the @samp{Ctrl-C} flag is set in the @value{GDBN}
|
|
reply packet (@pxref{The F Reply Packet}),
|
|
the target should behave as if it had
|
|
gotten a break message. The meaning for the target is ``system call
|
|
interrupted by @code{SIGINT}''. Consequentially, the target should actually stop
|
|
(as with a break message) and return to @value{GDBN} with a @code{T02}
|
|
packet.
|
|
|
|
It's important for the target to know in which
|
|
state the system call was interrupted. There are two possible cases:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
The system call hasn't been performed on the host yet.
|
|
|
|
@item
|
|
The system call on the host has been finished.
|
|
|
|
@end itemize
|
|
|
|
These two states can be distinguished by the target by the value of the
|
|
returned @code{errno}. If it's the protocol representation of @code{EINTR}, the system
|
|
call hasn't been performed. This is equivalent to the @code{EINTR} handling
|
|
on POSIX systems. In any other case, the target may presume that the
|
|
system call has been finished --- successfully or not --- and should behave
|
|
as if the break message arrived right after the system call.
|
|
|
|
@value{GDBN} must behave reliably. If the system call has not been called
|
|
yet, @value{GDBN} may send the @code{F} reply immediately, setting @code{EINTR} as
|
|
@code{errno} in the packet. If the system call on the host has been finished
|
|
before the user requests a break, the full action must be finished by
|
|
@value{GDBN}. This requires sending @code{M} or @code{X} packets as necessary.
|
|
The @code{F} packet may only be sent when either nothing has happened
|
|
or the full action has been completed.
|
|
|
|
@node Console I/O
|
|
@subsection Console I/O
|
|
@cindex console i/o as part of file-i/o
|
|
|
|
By default and if not explicitly closed by the target system, the file
|
|
descriptors 0, 1 and 2 are connected to the @value{GDBN} console. Output
|
|
on the @value{GDBN} console is handled as any other file output operation
|
|
(@code{write(1, @dots{})} or @code{write(2, @dots{})}). Console input is handled
|
|
by @value{GDBN} so that after the target read request from file descriptor
|
|
0 all following typing is buffered until either one of the following
|
|
conditions is met:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
The user types @kbd{Ctrl-c}. The behaviour is as explained above, and the
|
|
@code{read}
|
|
system call is treated as finished.
|
|
|
|
@item
|
|
The user presses @key{RET}. This is treated as end of input with a trailing
|
|
newline.
|
|
|
|
@item
|
|
The user types @kbd{Ctrl-d}. This is treated as end of input. No trailing
|
|
character (neither newline nor @samp{Ctrl-D}) is appended to the input.
|
|
|
|
@end itemize
|
|
|
|
If the user has typed more characters than fit in the buffer given to
|
|
the @code{read} call, the trailing characters are buffered in @value{GDBN} until
|
|
either another @code{read(0, @dots{})} is requested by the target, or debugging
|
|
is stopped at the user's request.
|
|
|
|
|
|
@node List of Supported Calls
|
|
@subsection List of Supported Calls
|
|
@cindex list of supported file-i/o calls
|
|
|
|
@menu
|
|
* open::
|
|
* close::
|
|
* read::
|
|
* write::
|
|
* lseek::
|
|
* rename::
|
|
* unlink::
|
|
* stat/fstat::
|
|
* gettimeofday::
|
|
* isatty::
|
|
* system::
|
|
@end menu
|
|
|
|
@node open
|
|
@unnumberedsubsubsec open
|
|
@cindex open, file-i/o system call
|
|
|
|
@table @asis
|
|
@item Synopsis:
|
|
@smallexample
|
|
int open(const char *pathname, int flags);
|
|
int open(const char *pathname, int flags, mode_t mode);
|
|
@end smallexample
|
|
|
|
@item Request:
|
|
@samp{Fopen,@var{pathptr}/@var{len},@var{flags},@var{mode}}
|
|
|
|
@noindent
|
|
@var{flags} is the bitwise @code{OR} of the following values:
|
|
|
|
@table @code
|
|
@item O_CREAT
|
|
If the file does not exist it will be created. The host
|
|
rules apply as far as file ownership and time stamps
|
|
are concerned.
|
|
|
|
@item O_EXCL
|
|
When used with @code{O_CREAT}, if the file already exists it is
|
|
an error and open() fails.
|
|
|
|
@item O_TRUNC
|
|
If the file already exists and the open mode allows
|
|
writing (@code{O_RDWR} or @code{O_WRONLY} is given) it will be
|
|
truncated to zero length.
|
|
|
|
@item O_APPEND
|
|
The file is opened in append mode.
|
|
|
|
@item O_RDONLY
|
|
The file is opened for reading only.
|
|
|
|
@item O_WRONLY
|
|
The file is opened for writing only.
|
|
|
|
@item O_RDWR
|
|
The file is opened for reading and writing.
|
|
@end table
|
|
|
|
@noindent
|
|
Other bits are silently ignored.
|
|
|
|
|
|
@noindent
|
|
@var{mode} is the bitwise @code{OR} of the following values:
|
|
|
|
@table @code
|
|
@item S_IRUSR
|
|
User has read permission.
|
|
|
|
@item S_IWUSR
|
|
User has write permission.
|
|
|
|
@item S_IRGRP
|
|
Group has read permission.
|
|
|
|
@item S_IWGRP
|
|
Group has write permission.
|
|
|
|
@item S_IROTH
|
|
Others have read permission.
|
|
|
|
@item S_IWOTH
|
|
Others have write permission.
|
|
@end table
|
|
|
|
@noindent
|
|
Other bits are silently ignored.
|
|
|
|
|
|
@item Return value:
|
|
@code{open} returns the new file descriptor or -1 if an error
|
|
occurred.
|
|
|
|
@item Errors:
|
|
|
|
@table @code
|
|
@item EEXIST
|
|
@var{pathname} already exists and @code{O_CREAT} and @code{O_EXCL} were used.
|
|
|
|
@item EISDIR
|
|
@var{pathname} refers to a directory.
|
|
|
|
@item EACCES
|
|
The requested access is not allowed.
|
|
|
|
@item ENAMETOOLONG
|
|
@var{pathname} was too long.
|
|
|
|
@item ENOENT
|
|
A directory component in @var{pathname} does not exist.
|
|
|
|
@item ENODEV
|
|
@var{pathname} refers to a device, pipe, named pipe or socket.
|
|
|
|
@item EROFS
|
|
@var{pathname} refers to a file on a read-only filesystem and
|
|
write access was requested.
|
|
|
|
@item EFAULT
|
|
@var{pathname} is an invalid pointer value.
|
|
|
|
@item ENOSPC
|
|
No space on device to create the file.
|
|
|
|
@item EMFILE
|
|
The process already has the maximum number of files open.
|
|
|
|
@item ENFILE
|
|
The limit on the total number of files open on the system
|
|
has been reached.
|
|
|
|
@item EINTR
|
|
The call was interrupted by the user.
|
|
@end table
|
|
|
|
@end table
|
|
|
|
@node close
|
|
@unnumberedsubsubsec close
|
|
@cindex close, file-i/o system call
|
|
|
|
@table @asis
|
|
@item Synopsis:
|
|
@smallexample
|
|
int close(int fd);
|
|
@end smallexample
|
|
|
|
@item Request:
|
|
@samp{Fclose,@var{fd}}
|
|
|
|
@item Return value:
|
|
@code{close} returns zero on success, or -1 if an error occurred.
|
|
|
|
@item Errors:
|
|
|
|
@table @code
|
|
@item EBADF
|
|
@var{fd} isn't a valid open file descriptor.
|
|
|
|
@item EINTR
|
|
The call was interrupted by the user.
|
|
@end table
|
|
|
|
@end table
|
|
|
|
@node read
|
|
@unnumberedsubsubsec read
|
|
@cindex read, file-i/o system call
|
|
|
|
@table @asis
|
|
@item Synopsis:
|
|
@smallexample
|
|
int read(int fd, void *buf, unsigned int count);
|
|
@end smallexample
|
|
|
|
@item Request:
|
|
@samp{Fread,@var{fd},@var{bufptr},@var{count}}
|
|
|
|
@item Return value:
|
|
On success, the number of bytes read is returned.
|
|
Zero indicates end of file. If count is zero, read
|
|
returns zero as well. On error, -1 is returned.
|
|
|
|
@item Errors:
|
|
|
|
@table @code
|
|
@item EBADF
|
|
@var{fd} is not a valid file descriptor or is not open for
|
|
reading.
|
|
|
|
@item EFAULT
|
|
@var{bufptr} is an invalid pointer value.
|
|
|
|
@item EINTR
|
|
The call was interrupted by the user.
|
|
@end table
|
|
|
|
@end table
|
|
|
|
@node write
|
|
@unnumberedsubsubsec write
|
|
@cindex write, file-i/o system call
|
|
|
|
@table @asis
|
|
@item Synopsis:
|
|
@smallexample
|
|
int write(int fd, const void *buf, unsigned int count);
|
|
@end smallexample
|
|
|
|
@item Request:
|
|
@samp{Fwrite,@var{fd},@var{bufptr},@var{count}}
|
|
|
|
@item Return value:
|
|
On success, the number of bytes written are returned.
|
|
Zero indicates nothing was written. On error, -1
|
|
is returned.
|
|
|
|
@item Errors:
|
|
|
|
@table @code
|
|
@item EBADF
|
|
@var{fd} is not a valid file descriptor or is not open for
|
|
writing.
|
|
|
|
@item EFAULT
|
|
@var{bufptr} is an invalid pointer value.
|
|
|
|
@item EFBIG
|
|
An attempt was made to write a file that exceeds the
|
|
host-specific maximum file size allowed.
|
|
|
|
@item ENOSPC
|
|
No space on device to write the data.
|
|
|
|
@item EINTR
|
|
The call was interrupted by the user.
|
|
@end table
|
|
|
|
@end table
|
|
|
|
@node lseek
|
|
@unnumberedsubsubsec lseek
|
|
@cindex lseek, file-i/o system call
|
|
|
|
@table @asis
|
|
@item Synopsis:
|
|
@smallexample
|
|
long lseek (int fd, long offset, int flag);
|
|
@end smallexample
|
|
|
|
@item Request:
|
|
@samp{Flseek,@var{fd},@var{offset},@var{flag}}
|
|
|
|
@var{flag} is one of:
|
|
|
|
@table @code
|
|
@item SEEK_SET
|
|
The offset is set to @var{offset} bytes.
|
|
|
|
@item SEEK_CUR
|
|
The offset is set to its current location plus @var{offset}
|
|
bytes.
|
|
|
|
@item SEEK_END
|
|
The offset is set to the size of the file plus @var{offset}
|
|
bytes.
|
|
@end table
|
|
|
|
@item Return value:
|
|
On success, the resulting unsigned offset in bytes from
|
|
the beginning of the file is returned. Otherwise, a
|
|
value of -1 is returned.
|
|
|
|
@item Errors:
|
|
|
|
@table @code
|
|
@item EBADF
|
|
@var{fd} is not a valid open file descriptor.
|
|
|
|
@item ESPIPE
|
|
@var{fd} is associated with the @value{GDBN} console.
|
|
|
|
@item EINVAL
|
|
@var{flag} is not a proper value.
|
|
|
|
@item EINTR
|
|
The call was interrupted by the user.
|
|
@end table
|
|
|
|
@end table
|
|
|
|
@node rename
|
|
@unnumberedsubsubsec rename
|
|
@cindex rename, file-i/o system call
|
|
|
|
@table @asis
|
|
@item Synopsis:
|
|
@smallexample
|
|
int rename(const char *oldpath, const char *newpath);
|
|
@end smallexample
|
|
|
|
@item Request:
|
|
@samp{Frename,@var{oldpathptr}/@var{len},@var{newpathptr}/@var{len}}
|
|
|
|
@item Return value:
|
|
On success, zero is returned. On error, -1 is returned.
|
|
|
|
@item Errors:
|
|
|
|
@table @code
|
|
@item EISDIR
|
|
@var{newpath} is an existing directory, but @var{oldpath} is not a
|
|
directory.
|
|
|
|
@item EEXIST
|
|
@var{newpath} is a non-empty directory.
|
|
|
|
@item EBUSY
|
|
@var{oldpath} or @var{newpath} is a directory that is in use by some
|
|
process.
|
|
|
|
@item EINVAL
|
|
An attempt was made to make a directory a subdirectory
|
|
of itself.
|
|
|
|
@item ENOTDIR
|
|
A component used as a directory in @var{oldpath} or new
|
|
path is not a directory. Or @var{oldpath} is a directory
|
|
and @var{newpath} exists but is not a directory.
|
|
|
|
@item EFAULT
|
|
@var{oldpathptr} or @var{newpathptr} are invalid pointer values.
|
|
|
|
@item EACCES
|
|
No access to the file or the path of the file.
|
|
|
|
@item ENAMETOOLONG
|
|
|
|
@var{oldpath} or @var{newpath} was too long.
|
|
|
|
@item ENOENT
|
|
A directory component in @var{oldpath} or @var{newpath} does not exist.
|
|
|
|
@item EROFS
|
|
The file is on a read-only filesystem.
|
|
|
|
@item ENOSPC
|
|
The device containing the file has no room for the new
|
|
directory entry.
|
|
|
|
@item EINTR
|
|
The call was interrupted by the user.
|
|
@end table
|
|
|
|
@end table
|
|
|
|
@node unlink
|
|
@unnumberedsubsubsec unlink
|
|
@cindex unlink, file-i/o system call
|
|
|
|
@table @asis
|
|
@item Synopsis:
|
|
@smallexample
|
|
int unlink(const char *pathname);
|
|
@end smallexample
|
|
|
|
@item Request:
|
|
@samp{Funlink,@var{pathnameptr}/@var{len}}
|
|
|
|
@item Return value:
|
|
On success, zero is returned. On error, -1 is returned.
|
|
|
|
@item Errors:
|
|
|
|
@table @code
|
|
@item EACCES
|
|
No access to the file or the path of the file.
|
|
|
|
@item EPERM
|
|
The system does not allow unlinking of directories.
|
|
|
|
@item EBUSY
|
|
The file @var{pathname} cannot be unlinked because it's
|
|
being used by another process.
|
|
|
|
@item EFAULT
|
|
@var{pathnameptr} is an invalid pointer value.
|
|
|
|
@item ENAMETOOLONG
|
|
@var{pathname} was too long.
|
|
|
|
@item ENOENT
|
|
A directory component in @var{pathname} does not exist.
|
|
|
|
@item ENOTDIR
|
|
A component of the path is not a directory.
|
|
|
|
@item EROFS
|
|
The file is on a read-only filesystem.
|
|
|
|
@item EINTR
|
|
The call was interrupted by the user.
|
|
@end table
|
|
|
|
@end table
|
|
|
|
@node stat/fstat
|
|
@unnumberedsubsubsec stat/fstat
|
|
@cindex fstat, file-i/o system call
|
|
@cindex stat, file-i/o system call
|
|
|
|
@table @asis
|
|
@item Synopsis:
|
|
@smallexample
|
|
int stat(const char *pathname, struct stat *buf);
|
|
int fstat(int fd, struct stat *buf);
|
|
@end smallexample
|
|
|
|
@item Request:
|
|
@samp{Fstat,@var{pathnameptr}/@var{len},@var{bufptr}}@*
|
|
@samp{Ffstat,@var{fd},@var{bufptr}}
|
|
|
|
@item Return value:
|
|
On success, zero is returned. On error, -1 is returned.
|
|
|
|
@item Errors:
|
|
|
|
@table @code
|
|
@item EBADF
|
|
@var{fd} is not a valid open file.
|
|
|
|
@item ENOENT
|
|
A directory component in @var{pathname} does not exist or the
|
|
path is an empty string.
|
|
|
|
@item ENOTDIR
|
|
A component of the path is not a directory.
|
|
|
|
@item EFAULT
|
|
@var{pathnameptr} is an invalid pointer value.
|
|
|
|
@item EACCES
|
|
No access to the file or the path of the file.
|
|
|
|
@item ENAMETOOLONG
|
|
@var{pathname} was too long.
|
|
|
|
@item EINTR
|
|
The call was interrupted by the user.
|
|
@end table
|
|
|
|
@end table
|
|
|
|
@node gettimeofday
|
|
@unnumberedsubsubsec gettimeofday
|
|
@cindex gettimeofday, file-i/o system call
|
|
|
|
@table @asis
|
|
@item Synopsis:
|
|
@smallexample
|
|
int gettimeofday(struct timeval *tv, void *tz);
|
|
@end smallexample
|
|
|
|
@item Request:
|
|
@samp{Fgettimeofday,@var{tvptr},@var{tzptr}}
|
|
|
|
@item Return value:
|
|
On success, 0 is returned, -1 otherwise.
|
|
|
|
@item Errors:
|
|
|
|
@table @code
|
|
@item EINVAL
|
|
@var{tz} is a non-NULL pointer.
|
|
|
|
@item EFAULT
|
|
@var{tvptr} and/or @var{tzptr} is an invalid pointer value.
|
|
@end table
|
|
|
|
@end table
|
|
|
|
@node isatty
|
|
@unnumberedsubsubsec isatty
|
|
@cindex isatty, file-i/o system call
|
|
|
|
@table @asis
|
|
@item Synopsis:
|
|
@smallexample
|
|
int isatty(int fd);
|
|
@end smallexample
|
|
|
|
@item Request:
|
|
@samp{Fisatty,@var{fd}}
|
|
|
|
@item Return value:
|
|
Returns 1 if @var{fd} refers to the @value{GDBN} console, 0 otherwise.
|
|
|
|
@item Errors:
|
|
|
|
@table @code
|
|
@item EINTR
|
|
The call was interrupted by the user.
|
|
@end table
|
|
|
|
@end table
|
|
|
|
Note that the @code{isatty} call is treated as a special case: it returns
|
|
1 to the target if the file descriptor is attached
|
|
to the @value{GDBN} console, 0 otherwise. Implementing through system calls
|
|
would require implementing @code{ioctl} and would be more complex than
|
|
needed.
|
|
|
|
|
|
@node system
|
|
@unnumberedsubsubsec system
|
|
@cindex system, file-i/o system call
|
|
|
|
@table @asis
|
|
@item Synopsis:
|
|
@smallexample
|
|
int system(const char *command);
|
|
@end smallexample
|
|
|
|
@item Request:
|
|
@samp{Fsystem,@var{commandptr}/@var{len}}
|
|
|
|
@item Return value:
|
|
If @var{len} is zero, the return value indicates whether a shell is
|
|
available. A zero return value indicates a shell is not available.
|
|
For non-zero @var{len}, the value returned is -1 on error and the
|
|
return status of the command otherwise. Only the exit status of the
|
|
command is returned, which is extracted from the host's @code{system}
|
|
return value by calling @code{WEXITSTATUS(retval)}. In case
|
|
@file{/bin/sh} could not be executed, 127 is returned.
|
|
|
|
@item Errors:
|
|
|
|
@table @code
|
|
@item EINTR
|
|
The call was interrupted by the user.
|
|
@end table
|
|
|
|
@end table
|
|
|
|
@value{GDBN} takes over the full task of calling the necessary host calls
|
|
to perform the @code{system} call. The return value of @code{system} on
|
|
the host is simplified before it's returned
|
|
to the target. Any termination signal information from the child process
|
|
is discarded, and the return value consists
|
|
entirely of the exit status of the called command.
|
|
|
|
Due to security concerns, the @code{system} call is by default refused
|
|
by @value{GDBN}. The user has to allow this call explicitly with the
|
|
@code{set remote system-call-allowed 1} command.
|
|
|
|
@table @code
|
|
@item set remote system-call-allowed
|
|
@kindex set remote system-call-allowed
|
|
Control whether to allow the @code{system} calls in the File I/O
|
|
protocol for the remote target. The default is zero (disabled).
|
|
|
|
@item show remote system-call-allowed
|
|
@kindex show remote system-call-allowed
|
|
Show whether the @code{system} calls are allowed in the File I/O
|
|
protocol.
|
|
@end table
|
|
|
|
@node Protocol-specific Representation of Datatypes
|
|
@subsection Protocol-specific Representation of Datatypes
|
|
@cindex protocol-specific representation of datatypes, in file-i/o protocol
|
|
|
|
@menu
|
|
* Integral Datatypes::
|
|
* Pointer Values::
|
|
* Memory Transfer::
|
|
* struct stat::
|
|
* struct timeval::
|
|
@end menu
|
|
|
|
@node Integral Datatypes
|
|
@unnumberedsubsubsec Integral Datatypes
|
|
@cindex integral datatypes, in file-i/o protocol
|
|
|
|
The integral datatypes used in the system calls are @code{int},
|
|
@code{unsigned int}, @code{long}, @code{unsigned long},
|
|
@code{mode_t}, and @code{time_t}.
|
|
|
|
@code{int}, @code{unsigned int}, @code{mode_t} and @code{time_t} are
|
|
implemented as 32 bit values in this protocol.
|
|
|
|
@code{long} and @code{unsigned long} are implemented as 64 bit types.
|
|
|
|
@xref{Limits}, for corresponding MIN and MAX values (similar to those
|
|
in @file{limits.h}) to allow range checking on host and target.
|
|
|
|
@code{time_t} datatypes are defined as seconds since the Epoch.
|
|
|
|
All integral datatypes transferred as part of a memory read or write of a
|
|
structured datatype e.g.@: a @code{struct stat} have to be given in big endian
|
|
byte order.
|
|
|
|
@node Pointer Values
|
|
@unnumberedsubsubsec Pointer Values
|
|
@cindex pointer values, in file-i/o protocol
|
|
|
|
Pointers to target data are transmitted as they are. An exception
|
|
is made for pointers to buffers for which the length isn't
|
|
transmitted as part of the function call, namely strings. Strings
|
|
are transmitted as a pointer/length pair, both as hex values, e.g.@:
|
|
|
|
@smallexample
|
|
@code{1aaf/12}
|
|
@end smallexample
|
|
|
|
@noindent
|
|
which is a pointer to data of length 18 bytes at position 0x1aaf.
|
|
The length is defined as the full string length in bytes, including
|
|
the trailing null byte. For example, the string @code{"hello world"}
|
|
at address 0x123456 is transmitted as
|
|
|
|
@smallexample
|
|
@code{123456/d}
|
|
@end smallexample
|
|
|
|
@node Memory Transfer
|
|
@unnumberedsubsubsec Memory Transfer
|
|
@cindex memory transfer, in file-i/o protocol
|
|
|
|
Structured data which is transferred using a memory read or write (for
|
|
example, a @code{struct stat}) is expected to be in a protocol-specific format
|
|
with all scalar multibyte datatypes being big endian. Translation to
|
|
this representation needs to be done both by the target before the @code{F}
|
|
packet is sent, and by @value{GDBN} before
|
|
it transfers memory to the target. Transferred pointers to structured
|
|
data should point to the already-coerced data at any time.
|
|
|
|
|
|
@node struct stat
|
|
@unnumberedsubsubsec struct stat
|
|
@cindex struct stat, in file-i/o protocol
|
|
|
|
The buffer of type @code{struct stat} used by the target and @value{GDBN}
|
|
is defined as follows:
|
|
|
|
@smallexample
|
|
struct stat @{
|
|
unsigned int st_dev; /* device */
|
|
unsigned int st_ino; /* inode */
|
|
mode_t st_mode; /* protection */
|
|
unsigned int st_nlink; /* number of hard links */
|
|
unsigned int st_uid; /* user ID of owner */
|
|
unsigned int st_gid; /* group ID of owner */
|
|
unsigned int st_rdev; /* device type (if inode device) */
|
|
unsigned long st_size; /* total size, in bytes */
|
|
unsigned long st_blksize; /* blocksize for filesystem I/O */
|
|
unsigned long st_blocks; /* number of blocks allocated */
|
|
time_t st_atime; /* time of last access */
|
|
time_t st_mtime; /* time of last modification */
|
|
time_t st_ctime; /* time of last change */
|
|
@};
|
|
@end smallexample
|
|
|
|
The integral datatypes conform to the definitions given in the
|
|
appropriate section (see @ref{Integral Datatypes}, for details) so this
|
|
structure is of size 64 bytes.
|
|
|
|
The values of several fields have a restricted meaning and/or
|
|
range of values.
|
|
|
|
@table @code
|
|
|
|
@item st_dev
|
|
A value of 0 represents a file, 1 the console.
|
|
|
|
@item st_ino
|
|
No valid meaning for the target. Transmitted unchanged.
|
|
|
|
@item st_mode
|
|
Valid mode bits are described in @ref{Constants}. Any other
|
|
bits have currently no meaning for the target.
|
|
|
|
@item st_uid
|
|
@itemx st_gid
|
|
@itemx st_rdev
|
|
No valid meaning for the target. Transmitted unchanged.
|
|
|
|
@item st_atime
|
|
@itemx st_mtime
|
|
@itemx st_ctime
|
|
These values have a host and file system dependent
|
|
accuracy. Especially on Windows hosts, the file system may not
|
|
support exact timing values.
|
|
@end table
|
|
|
|
The target gets a @code{struct stat} of the above representation and is
|
|
responsible for coercing it to the target representation before
|
|
continuing.
|
|
|
|
Note that due to size differences between the host, target, and protocol
|
|
representations of @code{struct stat} members, these members could eventually
|
|
get truncated on the target.
|
|
|
|
@node struct timeval
|
|
@unnumberedsubsubsec struct timeval
|
|
@cindex struct timeval, in file-i/o protocol
|
|
|
|
The buffer of type @code{struct timeval} used by the File-I/O protocol
|
|
is defined as follows:
|
|
|
|
@smallexample
|
|
struct timeval @{
|
|
time_t tv_sec; /* second */
|
|
long tv_usec; /* microsecond */
|
|
@};
|
|
@end smallexample
|
|
|
|
The integral datatypes conform to the definitions given in the
|
|
appropriate section (see @ref{Integral Datatypes}, for details) so this
|
|
structure is of size 8 bytes.
|
|
|
|
@node Constants
|
|
@subsection Constants
|
|
@cindex constants, in file-i/o protocol
|
|
|
|
The following values are used for the constants inside of the
|
|
protocol. @value{GDBN} and target are responsible for translating these
|
|
values before and after the call as needed.
|
|
|
|
@menu
|
|
* Open Flags::
|
|
* mode_t Values::
|
|
* Errno Values::
|
|
* Lseek Flags::
|
|
* Limits::
|
|
@end menu
|
|
|
|
@node Open Flags
|
|
@unnumberedsubsubsec Open Flags
|
|
@cindex open flags, in file-i/o protocol
|
|
|
|
All values are given in hexadecimal representation.
|
|
|
|
@smallexample
|
|
O_RDONLY 0x0
|
|
O_WRONLY 0x1
|
|
O_RDWR 0x2
|
|
O_APPEND 0x8
|
|
O_CREAT 0x200
|
|
O_TRUNC 0x400
|
|
O_EXCL 0x800
|
|
@end smallexample
|
|
|
|
@node mode_t Values
|
|
@unnumberedsubsubsec mode_t Values
|
|
@cindex mode_t values, in file-i/o protocol
|
|
|
|
All values are given in octal representation.
|
|
|
|
@smallexample
|
|
S_IFREG 0100000
|
|
S_IFDIR 040000
|
|
S_IRUSR 0400
|
|
S_IWUSR 0200
|
|
S_IXUSR 0100
|
|
S_IRGRP 040
|
|
S_IWGRP 020
|
|
S_IXGRP 010
|
|
S_IROTH 04
|
|
S_IWOTH 02
|
|
S_IXOTH 01
|
|
@end smallexample
|
|
|
|
@node Errno Values
|
|
@unnumberedsubsubsec Errno Values
|
|
@cindex errno values, in file-i/o protocol
|
|
|
|
All values are given in decimal representation.
|
|
|
|
@smallexample
|
|
EPERM 1
|
|
ENOENT 2
|
|
EINTR 4
|
|
EBADF 9
|
|
EACCES 13
|
|
EFAULT 14
|
|
EBUSY 16
|
|
EEXIST 17
|
|
ENODEV 19
|
|
ENOTDIR 20
|
|
EISDIR 21
|
|
EINVAL 22
|
|
ENFILE 23
|
|
EMFILE 24
|
|
EFBIG 27
|
|
ENOSPC 28
|
|
ESPIPE 29
|
|
EROFS 30
|
|
ENAMETOOLONG 91
|
|
EUNKNOWN 9999
|
|
@end smallexample
|
|
|
|
@code{EUNKNOWN} is used as a fallback error value if a host system returns
|
|
any error value not in the list of supported error numbers.
|
|
|
|
@node Lseek Flags
|
|
@unnumberedsubsubsec Lseek Flags
|
|
@cindex lseek flags, in file-i/o protocol
|
|
|
|
@smallexample
|
|
SEEK_SET 0
|
|
SEEK_CUR 1
|
|
SEEK_END 2
|
|
@end smallexample
|
|
|
|
@node Limits
|
|
@unnumberedsubsubsec Limits
|
|
@cindex limits, in file-i/o protocol
|
|
|
|
All values are given in decimal representation.
|
|
|
|
@smallexample
|
|
INT_MIN -2147483648
|
|
INT_MAX 2147483647
|
|
UINT_MAX 4294967295
|
|
LONG_MIN -9223372036854775808
|
|
LONG_MAX 9223372036854775807
|
|
ULONG_MAX 18446744073709551615
|
|
@end smallexample
|
|
|
|
@node File-I/O Examples
|
|
@subsection File-I/O Examples
|
|
@cindex file-i/o examples
|
|
|
|
Example sequence of a write call, file descriptor 3, buffer is at target
|
|
address 0x1234, 6 bytes should be written:
|
|
|
|
@smallexample
|
|
<- @code{Fwrite,3,1234,6}
|
|
@emph{request memory read from target}
|
|
-> @code{m1234,6}
|
|
<- XXXXXX
|
|
@emph{return "6 bytes written"}
|
|
-> @code{F6}
|
|
@end smallexample
|
|
|
|
Example sequence of a read call, file descriptor 3, buffer is at target
|
|
address 0x1234, 6 bytes should be read:
|
|
|
|
@smallexample
|
|
<- @code{Fread,3,1234,6}
|
|
@emph{request memory write to target}
|
|
-> @code{X1234,6:XXXXXX}
|
|
@emph{return "6 bytes read"}
|
|
-> @code{F6}
|
|
@end smallexample
|
|
|
|
Example sequence of a read call, call fails on the host due to invalid
|
|
file descriptor (@code{EBADF}):
|
|
|
|
@smallexample
|
|
<- @code{Fread,3,1234,6}
|
|
-> @code{F-1,9}
|
|
@end smallexample
|
|
|
|
Example sequence of a read call, user presses @kbd{Ctrl-c} before syscall on
|
|
host is called:
|
|
|
|
@smallexample
|
|
<- @code{Fread,3,1234,6}
|
|
-> @code{F-1,4,C}
|
|
<- @code{T02}
|
|
@end smallexample
|
|
|
|
Example sequence of a read call, user presses @kbd{Ctrl-c} after syscall on
|
|
host is called:
|
|
|
|
@smallexample
|
|
<- @code{Fread,3,1234,6}
|
|
-> @code{X1234,6:XXXXXX}
|
|
<- @code{T02}
|
|
@end smallexample
|
|
|
|
@node Library List Format
|
|
@section Library List Format
|
|
@cindex library list format, remote protocol
|
|
|
|
On some platforms, a dynamic loader (e.g.@: @file{ld.so}) runs in the
|
|
same process as your application to manage libraries. In this case,
|
|
@value{GDBN} can use the loader's symbol table and normal memory
|
|
operations to maintain a list of shared libraries. On other
|
|
platforms, the operating system manages loaded libraries.
|
|
@value{GDBN} can not retrieve the list of currently loaded libraries
|
|
through memory operations, so it uses the @samp{qXfer:libraries:read}
|
|
packet (@pxref{qXfer library list read}) instead. The remote stub
|
|
queries the target's operating system and reports which libraries
|
|
are loaded.
|
|
|
|
The @samp{qXfer:libraries:read} packet returns an XML document which
|
|
lists loaded libraries and their offsets. Each library has an
|
|
associated name and one or more segment or section base addresses,
|
|
which report where the library was loaded in memory.
|
|
|
|
For the common case of libraries that are fully linked binaries, the
|
|
library should have a list of segments. If the target supports
|
|
dynamic linking of a relocatable object file, its library XML element
|
|
should instead include a list of allocated sections. The segment or
|
|
section bases are start addresses, not relocation offsets; they do not
|
|
depend on the library's link-time base addresses.
|
|
|
|
@value{GDBN} must be linked with the Expat library to support XML
|
|
library lists. @xref{Expat}.
|
|
|
|
A simple memory map, with one loaded library relocated by a single
|
|
offset, looks like this:
|
|
|
|
@smallexample
|
|
<library-list>
|
|
<library name="/lib/libc.so.6">
|
|
<segment address="0x10000000"/>
|
|
</library>
|
|
</library-list>
|
|
@end smallexample
|
|
|
|
Another simple memory map, with one loaded library with three
|
|
allocated sections (.text, .data, .bss), looks like this:
|
|
|
|
@smallexample
|
|
<library-list>
|
|
<library name="sharedlib.o">
|
|
<section address="0x10000000"/>
|
|
<section address="0x20000000"/>
|
|
<section address="0x30000000"/>
|
|
</library>
|
|
</library-list>
|
|
@end smallexample
|
|
|
|
The format of a library list is described by this DTD:
|
|
|
|
@smallexample
|
|
<!-- library-list: Root element with versioning -->
|
|
<!ELEMENT library-list (library)*>
|
|
<!ATTLIST library-list version CDATA #FIXED "1.0">
|
|
<!ELEMENT library (segment*, section*)>
|
|
<!ATTLIST library name CDATA #REQUIRED>
|
|
<!ELEMENT segment EMPTY>
|
|
<!ATTLIST segment address CDATA #REQUIRED>
|
|
<!ELEMENT section EMPTY>
|
|
<!ATTLIST section address CDATA #REQUIRED>
|
|
@end smallexample
|
|
|
|
In addition, segments and section descriptors cannot be mixed within a
|
|
single library element, and you must supply at least one segment or
|
|
section for each library.
|
|
|
|
@node Library List Format for SVR4 Targets
|
|
@section Library List Format for SVR4 Targets
|
|
@cindex library list format, remote protocol
|
|
|
|
On SVR4 platforms @value{GDBN} can use the symbol table of a dynamic loader
|
|
(e.g.@: @file{ld.so}) and normal memory operations to maintain a list of
|
|
shared libraries. Still a special library list provided by this packet is
|
|
more efficient for the @value{GDBN} remote protocol.
|
|
|
|
The @samp{qXfer:libraries-svr4:read} packet returns an XML document which lists
|
|
loaded libraries and their SVR4 linker parameters. For each library on SVR4
|
|
target, the following parameters are reported:
|
|
|
|
@itemize @minus
|
|
@item
|
|
@code{name}, the absolute file name from the @code{l_name} field of
|
|
@code{struct link_map}.
|
|
@item
|
|
@code{lm} with address of @code{struct link_map} used for TLS
|
|
(Thread Local Storage) access.
|
|
@item
|
|
@code{l_addr}, the displacement as read from the field @code{l_addr} of
|
|
@code{struct link_map}. For prelinked libraries this is not an absolute
|
|
memory address. It is a displacement of absolute memory address against
|
|
address the file was prelinked to during the library load.
|
|
@item
|
|
@code{l_ld}, which is memory address of the @code{PT_DYNAMIC} segment
|
|
@end itemize
|
|
|
|
Additionally the single @code{main-lm} attribute specifies address of
|
|
@code{struct link_map} used for the main executable. This parameter is used
|
|
for TLS access and its presence is optional.
|
|
|
|
@value{GDBN} must be linked with the Expat library to support XML
|
|
SVR4 library lists. @xref{Expat}.
|
|
|
|
A simple memory map, with two loaded libraries (which do not use prelink),
|
|
looks like this:
|
|
|
|
@smallexample
|
|
<library-list-svr4 version="1.0" main-lm="0xe4f8f8">
|
|
<library name="/lib/ld-linux.so.2" lm="0xe4f51c" l_addr="0xe2d000"
|
|
l_ld="0xe4eefc"/>
|
|
<library name="/lib/libc.so.6" lm="0xe4fbe8" l_addr="0x154000"
|
|
l_ld="0x152350"/>
|
|
</library-list-svr>
|
|
@end smallexample
|
|
|
|
The format of an SVR4 library list is described by this DTD:
|
|
|
|
@smallexample
|
|
<!-- library-list-svr4: Root element with versioning -->
|
|
<!ELEMENT library-list-svr4 (library)*>
|
|
<!ATTLIST library-list-svr4 version CDATA #FIXED "1.0">
|
|
<!ATTLIST library-list-svr4 main-lm CDATA #IMPLIED>
|
|
<!ELEMENT library EMPTY>
|
|
<!ATTLIST library name CDATA #REQUIRED>
|
|
<!ATTLIST library lm CDATA #REQUIRED>
|
|
<!ATTLIST library l_addr CDATA #REQUIRED>
|
|
<!ATTLIST library l_ld CDATA #REQUIRED>
|
|
@end smallexample
|
|
|
|
@node Memory Map Format
|
|
@section Memory Map Format
|
|
@cindex memory map format
|
|
|
|
To be able to write into flash memory, @value{GDBN} needs to obtain a
|
|
memory map from the target. This section describes the format of the
|
|
memory map.
|
|
|
|
The memory map is obtained using the @samp{qXfer:memory-map:read}
|
|
(@pxref{qXfer memory map read}) packet and is an XML document that
|
|
lists memory regions.
|
|
|
|
@value{GDBN} must be linked with the Expat library to support XML
|
|
memory maps. @xref{Expat}.
|
|
|
|
The top-level structure of the document is shown below:
|
|
|
|
@smallexample
|
|
<?xml version="1.0"?>
|
|
<!DOCTYPE memory-map
|
|
PUBLIC "+//IDN gnu.org//DTD GDB Memory Map V1.0//EN"
|
|
"http://sourceware.org/gdb/gdb-memory-map.dtd">
|
|
<memory-map>
|
|
region...
|
|
</memory-map>
|
|
@end smallexample
|
|
|
|
Each region can be either:
|
|
|
|
@itemize
|
|
|
|
@item
|
|
A region of RAM starting at @var{addr} and extending for @var{length}
|
|
bytes from there:
|
|
|
|
@smallexample
|
|
<memory type="ram" start="@var{addr}" length="@var{length}"/>
|
|
@end smallexample
|
|
|
|
|
|
@item
|
|
A region of read-only memory:
|
|
|
|
@smallexample
|
|
<memory type="rom" start="@var{addr}" length="@var{length}"/>
|
|
@end smallexample
|
|
|
|
|
|
@item
|
|
A region of flash memory, with erasure blocks @var{blocksize}
|
|
bytes in length:
|
|
|
|
@smallexample
|
|
<memory type="flash" start="@var{addr}" length="@var{length}">
|
|
<property name="blocksize">@var{blocksize}</property>
|
|
</memory>
|
|
@end smallexample
|
|
|
|
@end itemize
|
|
|
|
Regions must not overlap. @value{GDBN} assumes that areas of memory not covered
|
|
by the memory map are RAM, and uses the ordinary @samp{M} and @samp{X}
|
|
packets to write to addresses in such ranges.
|
|
|
|
The formal DTD for memory map format is given below:
|
|
|
|
@smallexample
|
|
<!-- ................................................... -->
|
|
<!-- Memory Map XML DTD ................................ -->
|
|
<!-- File: memory-map.dtd .............................. -->
|
|
<!-- .................................... .............. -->
|
|
<!-- memory-map.dtd -->
|
|
<!-- memory-map: Root element with versioning -->
|
|
<!ELEMENT memory-map (memory | property)>
|
|
<!ATTLIST memory-map version CDATA #FIXED "1.0.0">
|
|
<!ELEMENT memory (property)>
|
|
<!-- memory: Specifies a memory region,
|
|
and its type, or device. -->
|
|
<!ATTLIST memory type CDATA #REQUIRED
|
|
start CDATA #REQUIRED
|
|
length CDATA #REQUIRED
|
|
device CDATA #IMPLIED>
|
|
<!-- property: Generic attribute tag -->
|
|
<!ELEMENT property (#PCDATA | property)*>
|
|
<!ATTLIST property name CDATA #REQUIRED>
|
|
@end smallexample
|
|
|
|
@node Thread List Format
|
|
@section Thread List Format
|
|
@cindex thread list format
|
|
|
|
To efficiently update the list of threads and their attributes,
|
|
@value{GDBN} issues the @samp{qXfer:threads:read} packet
|
|
(@pxref{qXfer threads read}) and obtains the XML document with
|
|
the following structure:
|
|
|
|
@smallexample
|
|
<?xml version="1.0"?>
|
|
<threads>
|
|
<thread id="id" core="0">
|
|
... description ...
|
|
</thread>
|
|
</threads>
|
|
@end smallexample
|
|
|
|
Each @samp{thread} element must have the @samp{id} attribute that
|
|
identifies the thread (@pxref{thread-id syntax}). The
|
|
@samp{core} attribute, if present, specifies which processor core
|
|
the thread was last executing on. The content of the of @samp{thread}
|
|
element is interpreted as human-readable auxilliary information.
|
|
|
|
@node Traceframe Info Format
|
|
@section Traceframe Info Format
|
|
@cindex traceframe info format
|
|
|
|
To be able to know which objects in the inferior can be examined when
|
|
inspecting a tracepoint hit, @value{GDBN} needs to obtain the list of
|
|
memory ranges, registers and trace state variables that have been
|
|
collected in a traceframe.
|
|
|
|
This list is obtained using the @samp{qXfer:traceframe-info:read}
|
|
(@pxref{qXfer traceframe info read}) packet and is an XML document.
|
|
|
|
@value{GDBN} must be linked with the Expat library to support XML
|
|
traceframe info discovery. @xref{Expat}.
|
|
|
|
The top-level structure of the document is shown below:
|
|
|
|
@smallexample
|
|
<?xml version="1.0"?>
|
|
<!DOCTYPE traceframe-info
|
|
PUBLIC "+//IDN gnu.org//DTD GDB Memory Map V1.0//EN"
|
|
"http://sourceware.org/gdb/gdb-traceframe-info.dtd">
|
|
<traceframe-info>
|
|
block...
|
|
</traceframe-info>
|
|
@end smallexample
|
|
|
|
Each traceframe block can be either:
|
|
|
|
@itemize
|
|
|
|
@item
|
|
A region of collected memory starting at @var{addr} and extending for
|
|
@var{length} bytes from there:
|
|
|
|
@smallexample
|
|
<memory start="@var{addr}" length="@var{length}"/>
|
|
@end smallexample
|
|
|
|
@end itemize
|
|
|
|
The formal DTD for the traceframe info format is given below:
|
|
|
|
@smallexample
|
|
<!ELEMENT traceframe-info (memory)* >
|
|
<!ATTLIST traceframe-info version CDATA #FIXED "1.0">
|
|
|
|
<!ELEMENT memory EMPTY>
|
|
<!ATTLIST memory start CDATA #REQUIRED
|
|
length CDATA #REQUIRED>
|
|
@end smallexample
|
|
|
|
@include agentexpr.texi
|
|
|
|
@node Target Descriptions
|
|
@appendix Target Descriptions
|
|
@cindex target descriptions
|
|
|
|
One of the challenges of using @value{GDBN} to debug embedded systems
|
|
is that there are so many minor variants of each processor
|
|
architecture in use. It is common practice for vendors to start with
|
|
a standard processor core --- ARM, PowerPC, or @acronym{MIPS}, for example ---
|
|
and then make changes to adapt it to a particular market niche. Some
|
|
architectures have hundreds of variants, available from dozens of
|
|
vendors. This leads to a number of problems:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
With so many different customized processors, it is difficult for
|
|
the @value{GDBN} maintainers to keep up with the changes.
|
|
@item
|
|
Since individual variants may have short lifetimes or limited
|
|
audiences, it may not be worthwhile to carry information about every
|
|
variant in the @value{GDBN} source tree.
|
|
@item
|
|
When @value{GDBN} does support the architecture of the embedded system
|
|
at hand, the task of finding the correct architecture name to give the
|
|
@command{set architecture} command can be error-prone.
|
|
@end itemize
|
|
|
|
To address these problems, the @value{GDBN} remote protocol allows a
|
|
target system to not only identify itself to @value{GDBN}, but to
|
|
actually describe its own features. This lets @value{GDBN} support
|
|
processor variants it has never seen before --- to the extent that the
|
|
descriptions are accurate, and that @value{GDBN} understands them.
|
|
|
|
@value{GDBN} must be linked with the Expat library to support XML
|
|
target descriptions. @xref{Expat}.
|
|
|
|
@menu
|
|
* Retrieving Descriptions:: How descriptions are fetched from a target.
|
|
* Target Description Format:: The contents of a target description.
|
|
* Predefined Target Types:: Standard types available for target
|
|
descriptions.
|
|
* Standard Target Features:: Features @value{GDBN} knows about.
|
|
@end menu
|
|
|
|
@node Retrieving Descriptions
|
|
@section Retrieving Descriptions
|
|
|
|
Target descriptions can be read from the target automatically, or
|
|
specified by the user manually. The default behavior is to read the
|
|
description from the target. @value{GDBN} retrieves it via the remote
|
|
protocol using @samp{qXfer} requests (@pxref{General Query Packets,
|
|
qXfer}). The @var{annex} in the @samp{qXfer} packet will be
|
|
@samp{target.xml}. The contents of the @samp{target.xml} annex are an
|
|
XML document, of the form described in @ref{Target Description
|
|
Format}.
|
|
|
|
Alternatively, you can specify a file to read for the target description.
|
|
If a file is set, the target will not be queried. The commands to
|
|
specify a file are:
|
|
|
|
@table @code
|
|
@cindex set tdesc filename
|
|
@item set tdesc filename @var{path}
|
|
Read the target description from @var{path}.
|
|
|
|
@cindex unset tdesc filename
|
|
@item unset tdesc filename
|
|
Do not read the XML target description from a file. @value{GDBN}
|
|
will use the description supplied by the current target.
|
|
|
|
@cindex show tdesc filename
|
|
@item show tdesc filename
|
|
Show the filename to read for a target description, if any.
|
|
@end table
|
|
|
|
|
|
@node Target Description Format
|
|
@section Target Description Format
|
|
@cindex target descriptions, XML format
|
|
|
|
A target description annex is an @uref{http://www.w3.org/XML/, XML}
|
|
document which complies with the Document Type Definition provided in
|
|
the @value{GDBN} sources in @file{gdb/features/gdb-target.dtd}. This
|
|
means you can use generally available tools like @command{xmllint} to
|
|
check that your feature descriptions are well-formed and valid.
|
|
However, to help people unfamiliar with XML write descriptions for
|
|
their targets, we also describe the grammar here.
|
|
|
|
Target descriptions can identify the architecture of the remote target
|
|
and (for some architectures) provide information about custom register
|
|
sets. They can also identify the OS ABI of the remote target.
|
|
@value{GDBN} can use this information to autoconfigure for your
|
|
target, or to warn you if you connect to an unsupported target.
|
|
|
|
Here is a simple target description:
|
|
|
|
@smallexample
|
|
<target version="1.0">
|
|
<architecture>i386:x86-64</architecture>
|
|
</target>
|
|
@end smallexample
|
|
|
|
@noindent
|
|
This minimal description only says that the target uses
|
|
the x86-64 architecture.
|
|
|
|
A target description has the following overall form, with [ ] marking
|
|
optional elements and @dots{} marking repeatable elements. The elements
|
|
are explained further below.
|
|
|
|
@smallexample
|
|
<?xml version="1.0"?>
|
|
<!DOCTYPE target SYSTEM "gdb-target.dtd">
|
|
<target version="1.0">
|
|
@r{[}@var{architecture}@r{]}
|
|
@r{[}@var{osabi}@r{]}
|
|
@r{[}@var{compatible}@r{]}
|
|
@r{[}@var{feature}@dots{}@r{]}
|
|
</target>
|
|
@end smallexample
|
|
|
|
@noindent
|
|
The description is generally insensitive to whitespace and line
|
|
breaks, under the usual common-sense rules. The XML version
|
|
declaration and document type declaration can generally be omitted
|
|
(@value{GDBN} does not require them), but specifying them may be
|
|
useful for XML validation tools. The @samp{version} attribute for
|
|
@samp{<target>} may also be omitted, but we recommend
|
|
including it; if future versions of @value{GDBN} use an incompatible
|
|
revision of @file{gdb-target.dtd}, they will detect and report
|
|
the version mismatch.
|
|
|
|
@subsection Inclusion
|
|
@cindex target descriptions, inclusion
|
|
@cindex XInclude
|
|
@ifnotinfo
|
|
@cindex <xi:include>
|
|
@end ifnotinfo
|
|
|
|
It can sometimes be valuable to split a target description up into
|
|
several different annexes, either for organizational purposes, or to
|
|
share files between different possible target descriptions. You can
|
|
divide a description into multiple files by replacing any element of
|
|
the target description with an inclusion directive of the form:
|
|
|
|
@smallexample
|
|
<xi:include href="@var{document}"/>
|
|
@end smallexample
|
|
|
|
@noindent
|
|
When @value{GDBN} encounters an element of this form, it will retrieve
|
|
the named XML @var{document}, and replace the inclusion directive with
|
|
the contents of that document. If the current description was read
|
|
using @samp{qXfer}, then so will be the included document;
|
|
@var{document} will be interpreted as the name of an annex. If the
|
|
current description was read from a file, @value{GDBN} will look for
|
|
@var{document} as a file in the same directory where it found the
|
|
original description.
|
|
|
|
@subsection Architecture
|
|
@cindex <architecture>
|
|
|
|
An @samp{<architecture>} element has this form:
|
|
|
|
@smallexample
|
|
<architecture>@var{arch}</architecture>
|
|
@end smallexample
|
|
|
|
@var{arch} is one of the architectures from the set accepted by
|
|
@code{set architecture} (@pxref{Targets, ,Specifying a Debugging Target}).
|
|
|
|
@subsection OS ABI
|
|
@cindex @code{<osabi>}
|
|
|
|
This optional field was introduced in @value{GDBN} version 7.0.
|
|
Previous versions of @value{GDBN} ignore it.
|
|
|
|
An @samp{<osabi>} element has this form:
|
|
|
|
@smallexample
|
|
<osabi>@var{abi-name}</osabi>
|
|
@end smallexample
|
|
|
|
@var{abi-name} is an OS ABI name from the same selection accepted by
|
|
@w{@code{set osabi}} (@pxref{ABI, ,Configuring the Current ABI}).
|
|
|
|
@subsection Compatible Architecture
|
|
@cindex @code{<compatible>}
|
|
|
|
This optional field was introduced in @value{GDBN} version 7.0.
|
|
Previous versions of @value{GDBN} ignore it.
|
|
|
|
A @samp{<compatible>} element has this form:
|
|
|
|
@smallexample
|
|
<compatible>@var{arch}</compatible>
|
|
@end smallexample
|
|
|
|
@var{arch} is one of the architectures from the set accepted by
|
|
@code{set architecture} (@pxref{Targets, ,Specifying a Debugging Target}).
|
|
|
|
A @samp{<compatible>} element is used to specify that the target
|
|
is able to run binaries in some other than the main target architecture
|
|
given by the @samp{<architecture>} element. For example, on the
|
|
Cell Broadband Engine, the main architecture is @code{powerpc:common}
|
|
or @code{powerpc:common64}, but the system is able to run binaries
|
|
in the @code{spu} architecture as well. The way to describe this
|
|
capability with @samp{<compatible>} is as follows:
|
|
|
|
@smallexample
|
|
<architecture>powerpc:common</architecture>
|
|
<compatible>spu</compatible>
|
|
@end smallexample
|
|
|
|
@subsection Features
|
|
@cindex <feature>
|
|
|
|
Each @samp{<feature>} describes some logical portion of the target
|
|
system. Features are currently used to describe available CPU
|
|
registers and the types of their contents. A @samp{<feature>} element
|
|
has this form:
|
|
|
|
@smallexample
|
|
<feature name="@var{name}">
|
|
@r{[}@var{type}@dots{}@r{]}
|
|
@var{reg}@dots{}
|
|
</feature>
|
|
@end smallexample
|
|
|
|
@noindent
|
|
Each feature's name should be unique within the description. The name
|
|
of a feature does not matter unless @value{GDBN} has some special
|
|
knowledge of the contents of that feature; if it does, the feature
|
|
should have its standard name. @xref{Standard Target Features}.
|
|
|
|
@subsection Types
|
|
|
|
Any register's value is a collection of bits which @value{GDBN} must
|
|
interpret. The default interpretation is a two's complement integer,
|
|
but other types can be requested by name in the register description.
|
|
Some predefined types are provided by @value{GDBN} (@pxref{Predefined
|
|
Target Types}), and the description can define additional composite types.
|
|
|
|
Each type element must have an @samp{id} attribute, which gives
|
|
a unique (within the containing @samp{<feature>}) name to the type.
|
|
Types must be defined before they are used.
|
|
|
|
@cindex <vector>
|
|
Some targets offer vector registers, which can be treated as arrays
|
|
of scalar elements. These types are written as @samp{<vector>} elements,
|
|
specifying the array element type, @var{type}, and the number of elements,
|
|
@var{count}:
|
|
|
|
@smallexample
|
|
<vector id="@var{id}" type="@var{type}" count="@var{count}"/>
|
|
@end smallexample
|
|
|
|
@cindex <union>
|
|
If a register's value is usefully viewed in multiple ways, define it
|
|
with a union type containing the useful representations. The
|
|
@samp{<union>} element contains one or more @samp{<field>} elements,
|
|
each of which has a @var{name} and a @var{type}:
|
|
|
|
@smallexample
|
|
<union id="@var{id}">
|
|
<field name="@var{name}" type="@var{type}"/>
|
|
@dots{}
|
|
</union>
|
|
@end smallexample
|
|
|
|
@cindex <struct>
|
|
If a register's value is composed from several separate values, define
|
|
it with a structure type. There are two forms of the @samp{<struct>}
|
|
element; a @samp{<struct>} element must either contain only bitfields
|
|
or contain no bitfields. If the structure contains only bitfields,
|
|
its total size in bytes must be specified, each bitfield must have an
|
|
explicit start and end, and bitfields are automatically assigned an
|
|
integer type. The field's @var{start} should be less than or
|
|
equal to its @var{end}, and zero represents the least significant bit.
|
|
|
|
@smallexample
|
|
<struct id="@var{id}" size="@var{size}">
|
|
<field name="@var{name}" start="@var{start}" end="@var{end}"/>
|
|
@dots{}
|
|
</struct>
|
|
@end smallexample
|
|
|
|
If the structure contains no bitfields, then each field has an
|
|
explicit type, and no implicit padding is added.
|
|
|
|
@smallexample
|
|
<struct id="@var{id}">
|
|
<field name="@var{name}" type="@var{type}"/>
|
|
@dots{}
|
|
</struct>
|
|
@end smallexample
|
|
|
|
@cindex <flags>
|
|
If a register's value is a series of single-bit flags, define it with
|
|
a flags type. The @samp{<flags>} element has an explicit @var{size}
|
|
and contains one or more @samp{<field>} elements. Each field has a
|
|
@var{name}, a @var{start}, and an @var{end}. Only single-bit flags
|
|
are supported.
|
|
|
|
@smallexample
|
|
<flags id="@var{id}" size="@var{size}">
|
|
<field name="@var{name}" start="@var{start}" end="@var{end}"/>
|
|
@dots{}
|
|
</flags>
|
|
@end smallexample
|
|
|
|
@subsection Registers
|
|
@cindex <reg>
|
|
|
|
Each register is represented as an element with this form:
|
|
|
|
@smallexample
|
|
<reg name="@var{name}"
|
|
bitsize="@var{size}"
|
|
@r{[}regnum="@var{num}"@r{]}
|
|
@r{[}save-restore="@var{save-restore}"@r{]}
|
|
@r{[}type="@var{type}"@r{]}
|
|
@r{[}group="@var{group}"@r{]}/>
|
|
@end smallexample
|
|
|
|
@noindent
|
|
The components are as follows:
|
|
|
|
@table @var
|
|
|
|
@item name
|
|
The register's name; it must be unique within the target description.
|
|
|
|
@item bitsize
|
|
The register's size, in bits.
|
|
|
|
@item regnum
|
|
The register's number. If omitted, a register's number is one greater
|
|
than that of the previous register (either in the current feature or in
|
|
a preceding feature); the first register in the target description
|
|
defaults to zero. This register number is used to read or write
|
|
the register; e.g.@: it is used in the remote @code{p} and @code{P}
|
|
packets, and registers appear in the @code{g} and @code{G} packets
|
|
in order of increasing register number.
|
|
|
|
@item save-restore
|
|
Whether the register should be preserved across inferior function
|
|
calls; this must be either @code{yes} or @code{no}. The default is
|
|
@code{yes}, which is appropriate for most registers except for
|
|
some system control registers; this is not related to the target's
|
|
ABI.
|
|
|
|
@item type
|
|
The type of the register. @var{type} may be a predefined type, a type
|
|
defined in the current feature, or one of the special types @code{int}
|
|
and @code{float}. @code{int} is an integer type of the correct size
|
|
for @var{bitsize}, and @code{float} is a floating point type (in the
|
|
architecture's normal floating point format) of the correct size for
|
|
@var{bitsize}. The default is @code{int}.
|
|
|
|
@item group
|
|
The register group to which this register belongs. @var{group} must
|
|
be either @code{general}, @code{float}, or @code{vector}. If no
|
|
@var{group} is specified, @value{GDBN} will not display the register
|
|
in @code{info registers}.
|
|
|
|
@end table
|
|
|
|
@node Predefined Target Types
|
|
@section Predefined Target Types
|
|
@cindex target descriptions, predefined types
|
|
|
|
Type definitions in the self-description can build up composite types
|
|
from basic building blocks, but can not define fundamental types. Instead,
|
|
standard identifiers are provided by @value{GDBN} for the fundamental
|
|
types. The currently supported types are:
|
|
|
|
@table @code
|
|
|
|
@item int8
|
|
@itemx int16
|
|
@itemx int32
|
|
@itemx int64
|
|
@itemx int128
|
|
Signed integer types holding the specified number of bits.
|
|
|
|
@item uint8
|
|
@itemx uint16
|
|
@itemx uint32
|
|
@itemx uint64
|
|
@itemx uint128
|
|
Unsigned integer types holding the specified number of bits.
|
|
|
|
@item code_ptr
|
|
@itemx data_ptr
|
|
Pointers to unspecified code and data. The program counter and
|
|
any dedicated return address register may be marked as code
|
|
pointers; printing a code pointer converts it into a symbolic
|
|
address. The stack pointer and any dedicated address registers
|
|
may be marked as data pointers.
|
|
|
|
@item ieee_single
|
|
Single precision IEEE floating point.
|
|
|
|
@item ieee_double
|
|
Double precision IEEE floating point.
|
|
|
|
@item arm_fpa_ext
|
|
The 12-byte extended precision format used by ARM FPA registers.
|
|
|
|
@item i387_ext
|
|
The 10-byte extended precision format used by x87 registers.
|
|
|
|
@item i386_eflags
|
|
32bit @sc{eflags} register used by x86.
|
|
|
|
@item i386_mxcsr
|
|
32bit @sc{mxcsr} register used by x86.
|
|
|
|
@end table
|
|
|
|
@node Standard Target Features
|
|
@section Standard Target Features
|
|
@cindex target descriptions, standard features
|
|
|
|
A target description must contain either no registers or all the
|
|
target's registers. If the description contains no registers, then
|
|
@value{GDBN} will assume a default register layout, selected based on
|
|
the architecture. If the description contains any registers, the
|
|
default layout will not be used; the standard registers must be
|
|
described in the target description, in such a way that @value{GDBN}
|
|
can recognize them.
|
|
|
|
This is accomplished by giving specific names to feature elements
|
|
which contain standard registers. @value{GDBN} will look for features
|
|
with those names and verify that they contain the expected registers;
|
|
if any known feature is missing required registers, or if any required
|
|
feature is missing, @value{GDBN} will reject the target
|
|
description. You can add additional registers to any of the
|
|
standard features --- @value{GDBN} will display them just as if
|
|
they were added to an unrecognized feature.
|
|
|
|
This section lists the known features and their expected contents.
|
|
Sample XML documents for these features are included in the
|
|
@value{GDBN} source tree, in the directory @file{gdb/features}.
|
|
|
|
Names recognized by @value{GDBN} should include the name of the
|
|
company or organization which selected the name, and the overall
|
|
architecture to which the feature applies; so e.g.@: the feature
|
|
containing ARM core registers is named @samp{org.gnu.gdb.arm.core}.
|
|
|
|
The names of registers are not case sensitive for the purpose
|
|
of recognizing standard features, but @value{GDBN} will only display
|
|
registers using the capitalization used in the description.
|
|
|
|
@menu
|
|
* ARM Features::
|
|
* i386 Features::
|
|
* MIPS Features::
|
|
* M68K Features::
|
|
* PowerPC Features::
|
|
* TIC6x Features::
|
|
@end menu
|
|
|
|
|
|
@node ARM Features
|
|
@subsection ARM Features
|
|
@cindex target descriptions, ARM features
|
|
|
|
The @samp{org.gnu.gdb.arm.core} feature is required for non-M-profile
|
|
ARM targets.
|
|
It should contain registers @samp{r0} through @samp{r13}, @samp{sp},
|
|
@samp{lr}, @samp{pc}, and @samp{cpsr}.
|
|
|
|
For M-profile targets (e.g. Cortex-M3), the @samp{org.gnu.gdb.arm.core}
|
|
feature is replaced by @samp{org.gnu.gdb.arm.m-profile}. It should contain
|
|
registers @samp{r0} through @samp{r13}, @samp{sp}, @samp{lr}, @samp{pc},
|
|
and @samp{xpsr}.
|
|
|
|
The @samp{org.gnu.gdb.arm.fpa} feature is optional. If present, it
|
|
should contain registers @samp{f0} through @samp{f7} and @samp{fps}.
|
|
|
|
The @samp{org.gnu.gdb.xscale.iwmmxt} feature is optional. If present,
|
|
it should contain at least registers @samp{wR0} through @samp{wR15} and
|
|
@samp{wCGR0} through @samp{wCGR3}. The @samp{wCID}, @samp{wCon},
|
|
@samp{wCSSF}, and @samp{wCASF} registers are optional.
|
|
|
|
The @samp{org.gnu.gdb.arm.vfp} feature is optional. If present, it
|
|
should contain at least registers @samp{d0} through @samp{d15}. If
|
|
they are present, @samp{d16} through @samp{d31} should also be included.
|
|
@value{GDBN} will synthesize the single-precision registers from
|
|
halves of the double-precision registers.
|
|
|
|
The @samp{org.gnu.gdb.arm.neon} feature is optional. It does not
|
|
need to contain registers; it instructs @value{GDBN} to display the
|
|
VFP double-precision registers as vectors and to synthesize the
|
|
quad-precision registers from pairs of double-precision registers.
|
|
If this feature is present, @samp{org.gnu.gdb.arm.vfp} must also
|
|
be present and include 32 double-precision registers.
|
|
|
|
@node i386 Features
|
|
@subsection i386 Features
|
|
@cindex target descriptions, i386 features
|
|
|
|
The @samp{org.gnu.gdb.i386.core} feature is required for i386/amd64
|
|
targets. It should describe the following registers:
|
|
|
|
@itemize @minus
|
|
@item
|
|
@samp{eax} through @samp{edi} plus @samp{eip} for i386
|
|
@item
|
|
@samp{rax} through @samp{r15} plus @samp{rip} for amd64
|
|
@item
|
|
@samp{eflags}, @samp{cs}, @samp{ss}, @samp{ds}, @samp{es},
|
|
@samp{fs}, @samp{gs}
|
|
@item
|
|
@samp{st0} through @samp{st7}
|
|
@item
|
|
@samp{fctrl}, @samp{fstat}, @samp{ftag}, @samp{fiseg}, @samp{fioff},
|
|
@samp{foseg}, @samp{fooff} and @samp{fop}
|
|
@end itemize
|
|
|
|
The register sets may be different, depending on the target.
|
|
|
|
The @samp{org.gnu.gdb.i386.sse} feature is optional. It should
|
|
describe registers:
|
|
|
|
@itemize @minus
|
|
@item
|
|
@samp{xmm0} through @samp{xmm7} for i386
|
|
@item
|
|
@samp{xmm0} through @samp{xmm15} for amd64
|
|
@item
|
|
@samp{mxcsr}
|
|
@end itemize
|
|
|
|
The @samp{org.gnu.gdb.i386.avx} feature is optional and requires the
|
|
@samp{org.gnu.gdb.i386.sse} feature. It should
|
|
describe the upper 128 bits of @sc{ymm} registers:
|
|
|
|
@itemize @minus
|
|
@item
|
|
@samp{ymm0h} through @samp{ymm7h} for i386
|
|
@item
|
|
@samp{ymm0h} through @samp{ymm15h} for amd64
|
|
@end itemize
|
|
|
|
The @samp{org.gnu.gdb.i386.linux} feature is optional. It should
|
|
describe a single register, @samp{orig_eax}.
|
|
|
|
@node MIPS Features
|
|
@subsection @acronym{MIPS} Features
|
|
@cindex target descriptions, @acronym{MIPS} features
|
|
|
|
The @samp{org.gnu.gdb.mips.cpu} feature is required for @acronym{MIPS} targets.
|
|
It should contain registers @samp{r0} through @samp{r31}, @samp{lo},
|
|
@samp{hi}, and @samp{pc}. They may be 32-bit or 64-bit depending
|
|
on the target.
|
|
|
|
The @samp{org.gnu.gdb.mips.cp0} feature is also required. It should
|
|
contain at least the @samp{status}, @samp{badvaddr}, and @samp{cause}
|
|
registers. They may be 32-bit or 64-bit depending on the target.
|
|
|
|
The @samp{org.gnu.gdb.mips.fpu} feature is currently required, though
|
|
it may be optional in a future version of @value{GDBN}. It should
|
|
contain registers @samp{f0} through @samp{f31}, @samp{fcsr}, and
|
|
@samp{fir}. They may be 32-bit or 64-bit depending on the target.
|
|
|
|
The @samp{org.gnu.gdb.mips.dsp} feature is optional. It should
|
|
contain registers @samp{hi1} through @samp{hi3}, @samp{lo1} through
|
|
@samp{lo3}, and @samp{dspctl}. The @samp{dspctl} register should
|
|
be 32-bit and the rest may be 32-bit or 64-bit depending on the target.
|
|
|
|
The @samp{org.gnu.gdb.mips.linux} feature is optional. It should
|
|
contain a single register, @samp{restart}, which is used by the
|
|
Linux kernel to control restartable syscalls.
|
|
|
|
@node M68K Features
|
|
@subsection M68K Features
|
|
@cindex target descriptions, M68K features
|
|
|
|
@table @code
|
|
@item @samp{org.gnu.gdb.m68k.core}
|
|
@itemx @samp{org.gnu.gdb.coldfire.core}
|
|
@itemx @samp{org.gnu.gdb.fido.core}
|
|
One of those features must be always present.
|
|
The feature that is present determines which flavor of m68k is
|
|
used. The feature that is present should contain registers
|
|
@samp{d0} through @samp{d7}, @samp{a0} through @samp{a5}, @samp{fp},
|
|
@samp{sp}, @samp{ps} and @samp{pc}.
|
|
|
|
@item @samp{org.gnu.gdb.coldfire.fp}
|
|
This feature is optional. If present, it should contain registers
|
|
@samp{fp0} through @samp{fp7}, @samp{fpcontrol}, @samp{fpstatus} and
|
|
@samp{fpiaddr}.
|
|
@end table
|
|
|
|
@node PowerPC Features
|
|
@subsection PowerPC Features
|
|
@cindex target descriptions, PowerPC features
|
|
|
|
The @samp{org.gnu.gdb.power.core} feature is required for PowerPC
|
|
targets. It should contain registers @samp{r0} through @samp{r31},
|
|
@samp{pc}, @samp{msr}, @samp{cr}, @samp{lr}, @samp{ctr}, and
|
|
@samp{xer}. They may be 32-bit or 64-bit depending on the target.
|
|
|
|
The @samp{org.gnu.gdb.power.fpu} feature is optional. It should
|
|
contain registers @samp{f0} through @samp{f31} and @samp{fpscr}.
|
|
|
|
The @samp{org.gnu.gdb.power.altivec} feature is optional. It should
|
|
contain registers @samp{vr0} through @samp{vr31}, @samp{vscr},
|
|
and @samp{vrsave}.
|
|
|
|
The @samp{org.gnu.gdb.power.vsx} feature is optional. It should
|
|
contain registers @samp{vs0h} through @samp{vs31h}. @value{GDBN}
|
|
will combine these registers with the floating point registers
|
|
(@samp{f0} through @samp{f31}) and the altivec registers (@samp{vr0}
|
|
through @samp{vr31}) to present the 128-bit wide registers @samp{vs0}
|
|
through @samp{vs63}, the set of vector registers for POWER7.
|
|
|
|
The @samp{org.gnu.gdb.power.spe} feature is optional. It should
|
|
contain registers @samp{ev0h} through @samp{ev31h}, @samp{acc}, and
|
|
@samp{spefscr}. SPE targets should provide 32-bit registers in
|
|
@samp{org.gnu.gdb.power.core} and provide the upper halves in
|
|
@samp{ev0h} through @samp{ev31h}. @value{GDBN} will combine
|
|
these to present registers @samp{ev0} through @samp{ev31} to the
|
|
user.
|
|
|
|
@node TIC6x Features
|
|
@subsection TMS320C6x Features
|
|
@cindex target descriptions, TIC6x features
|
|
@cindex target descriptions, TMS320C6x features
|
|
The @samp{org.gnu.gdb.tic6x.core} feature is required for TMS320C6x
|
|
targets. It should contain registers @samp{A0} through @samp{A15},
|
|
registers @samp{B0} through @samp{B15}, @samp{CSR} and @samp{PC}.
|
|
|
|
The @samp{org.gnu.gdb.tic6x.gp} feature is optional. It should
|
|
contain registers @samp{A16} through @samp{A31} and @samp{B16}
|
|
through @samp{B31}.
|
|
|
|
The @samp{org.gnu.gdb.tic6x.c6xp} feature is optional. It should
|
|
contain registers @samp{TSR}, @samp{ILC} and @samp{RILC}.
|
|
|
|
@node Operating System Information
|
|
@appendix Operating System Information
|
|
@cindex operating system information
|
|
|
|
@menu
|
|
* Process list::
|
|
@end menu
|
|
|
|
Users of @value{GDBN} often wish to obtain information about the state of
|
|
the operating system running on the target---for example the list of
|
|
processes, or the list of open files. This section describes the
|
|
mechanism that makes it possible. This mechanism is similar to the
|
|
target features mechanism (@pxref{Target Descriptions}), but focuses
|
|
on a different aspect of target.
|
|
|
|
Operating system information is retrived from the target via the
|
|
remote protocol, using @samp{qXfer} requests (@pxref{qXfer osdata
|
|
read}). The object name in the request should be @samp{osdata}, and
|
|
the @var{annex} identifies the data to be fetched.
|
|
|
|
@node Process list
|
|
@appendixsection Process list
|
|
@cindex operating system information, process list
|
|
|
|
When requesting the process list, the @var{annex} field in the
|
|
@samp{qXfer} request should be @samp{processes}. The returned data is
|
|
an XML document. The formal syntax of this document is defined in
|
|
@file{gdb/features/osdata.dtd}.
|
|
|
|
An example document is:
|
|
|
|
@smallexample
|
|
<?xml version="1.0"?>
|
|
<!DOCTYPE target SYSTEM "osdata.dtd">
|
|
<osdata type="processes">
|
|
<item>
|
|
<column name="pid">1</column>
|
|
<column name="user">root</column>
|
|
<column name="command">/sbin/init</column>
|
|
<column name="cores">1,2,3</column>
|
|
</item>
|
|
</osdata>
|
|
@end smallexample
|
|
|
|
Each item should include a column whose name is @samp{pid}. The value
|
|
of that column should identify the process on the target. The
|
|
@samp{user} and @samp{command} columns are optional, and will be
|
|
displayed by @value{GDBN}. The @samp{cores} column, if present,
|
|
should contain a comma-separated list of cores that this process
|
|
is running on. Target may provide additional columns,
|
|
which @value{GDBN} currently ignores.
|
|
|
|
@node Trace File Format
|
|
@appendix Trace File Format
|
|
@cindex trace file format
|
|
|
|
The trace file comes in three parts: a header, a textual description
|
|
section, and a trace frame section with binary data.
|
|
|
|
The header has the form @code{\x7fTRACE0\n}. The first byte is
|
|
@code{0x7f} so as to indicate that the file contains binary data,
|
|
while the @code{0} is a version number that may have different values
|
|
in the future.
|
|
|
|
The description section consists of multiple lines of @sc{ascii} text
|
|
separated by newline characters (@code{0xa}). The lines may include a
|
|
variety of optional descriptive or context-setting information, such
|
|
as tracepoint definitions or register set size. @value{GDBN} will
|
|
ignore any line that it does not recognize. An empty line marks the end
|
|
of this section.
|
|
|
|
@c FIXME add some specific types of data
|
|
|
|
The trace frame section consists of a number of consecutive frames.
|
|
Each frame begins with a two-byte tracepoint number, followed by a
|
|
four-byte size giving the amount of data in the frame. The data in
|
|
the frame consists of a number of blocks, each introduced by a
|
|
character indicating its type (at least register, memory, and trace
|
|
state variable). The data in this section is raw binary, not a
|
|
hexadecimal or other encoding; its endianness matches the target's
|
|
endianness.
|
|
|
|
@c FIXME bi-arch may require endianness/arch info in description section
|
|
|
|
@table @code
|
|
@item R @var{bytes}
|
|
Register block. The number and ordering of bytes matches that of a
|
|
@code{g} packet in the remote protocol. Note that these are the
|
|
actual bytes, in target order and @value{GDBN} register order, not a
|
|
hexadecimal encoding.
|
|
|
|
@item M @var{address} @var{length} @var{bytes}...
|
|
Memory block. This is a contiguous block of memory, at the 8-byte
|
|
address @var{address}, with a 2-byte length @var{length}, followed by
|
|
@var{length} bytes.
|
|
|
|
@item V @var{number} @var{value}
|
|
Trace state variable block. This records the 8-byte signed value
|
|
@var{value} of trace state variable numbered @var{number}.
|
|
|
|
@end table
|
|
|
|
Future enhancements of the trace file format may include additional types
|
|
of blocks.
|
|
|
|
@node Index Section Format
|
|
@appendix @code{.gdb_index} section format
|
|
@cindex .gdb_index section format
|
|
@cindex index section format
|
|
|
|
This section documents the index section that is created by @code{save
|
|
gdb-index} (@pxref{Index Files}). The index section is
|
|
DWARF-specific; some knowledge of DWARF is assumed in this
|
|
description.
|
|
|
|
The mapped index file format is designed to be directly
|
|
@code{mmap}able on any architecture. In most cases, a datum is
|
|
represented using a little-endian 32-bit integer value, called an
|
|
@code{offset_type}. Big endian machines must byte-swap the values
|
|
before using them. Exceptions to this rule are noted. The data is
|
|
laid out such that alignment is always respected.
|
|
|
|
A mapped index consists of several areas, laid out in order.
|
|
|
|
@enumerate
|
|
@item
|
|
The file header. This is a sequence of values, of @code{offset_type}
|
|
unless otherwise noted:
|
|
|
|
@enumerate
|
|
@item
|
|
The version number, currently 7. Versions 1, 2 and 3 are obsolete.
|
|
Version 4 uses a different hashing function from versions 5 and 6.
|
|
Version 6 includes symbols for inlined functions, whereas versions 4
|
|
and 5 do not. Version 7 adds attributes to the CU indices in the
|
|
symbol table. @value{GDBN} will only read version 4, 5, or 6 indices
|
|
by specifying @code{set use-deprecated-index-sections on}.
|
|
|
|
@item
|
|
The offset, from the start of the file, of the CU list.
|
|
|
|
@item
|
|
The offset, from the start of the file, of the types CU list. Note
|
|
that this area can be empty, in which case this offset will be equal
|
|
to the next offset.
|
|
|
|
@item
|
|
The offset, from the start of the file, of the address area.
|
|
|
|
@item
|
|
The offset, from the start of the file, of the symbol table.
|
|
|
|
@item
|
|
The offset, from the start of the file, of the constant pool.
|
|
@end enumerate
|
|
|
|
@item
|
|
The CU list. This is a sequence of pairs of 64-bit little-endian
|
|
values, sorted by the CU offset. The first element in each pair is
|
|
the offset of a CU in the @code{.debug_info} section. The second
|
|
element in each pair is the length of that CU. References to a CU
|
|
elsewhere in the map are done using a CU index, which is just the
|
|
0-based index into this table. Note that if there are type CUs, then
|
|
conceptually CUs and type CUs form a single list for the purposes of
|
|
CU indices.
|
|
|
|
@item
|
|
The types CU list. This is a sequence of triplets of 64-bit
|
|
little-endian values. In a triplet, the first value is the CU offset,
|
|
the second value is the type offset in the CU, and the third value is
|
|
the type signature. The types CU list is not sorted.
|
|
|
|
@item
|
|
The address area. The address area consists of a sequence of address
|
|
entries. Each address entry has three elements:
|
|
|
|
@enumerate
|
|
@item
|
|
The low address. This is a 64-bit little-endian value.
|
|
|
|
@item
|
|
The high address. This is a 64-bit little-endian value. Like
|
|
@code{DW_AT_high_pc}, the value is one byte beyond the end.
|
|
|
|
@item
|
|
The CU index. This is an @code{offset_type} value.
|
|
@end enumerate
|
|
|
|
@item
|
|
The symbol table. This is an open-addressed hash table. The size of
|
|
the hash table is always a power of 2.
|
|
|
|
Each slot in the hash table consists of a pair of @code{offset_type}
|
|
values. The first value is the offset of the symbol's name in the
|
|
constant pool. The second value is the offset of the CU vector in the
|
|
constant pool.
|
|
|
|
If both values are 0, then this slot in the hash table is empty. This
|
|
is ok because while 0 is a valid constant pool index, it cannot be a
|
|
valid index for both a string and a CU vector.
|
|
|
|
The hash value for a table entry is computed by applying an
|
|
iterative hash function to the symbol's name. Starting with an
|
|
initial value of @code{r = 0}, each (unsigned) character @samp{c} in
|
|
the string is incorporated into the hash using the formula depending on the
|
|
index version:
|
|
|
|
@table @asis
|
|
@item Version 4
|
|
The formula is @code{r = r * 67 + c - 113}.
|
|
|
|
@item Versions 5 to 7
|
|
The formula is @code{r = r * 67 + tolower (c) - 113}.
|
|
@end table
|
|
|
|
The terminating @samp{\0} is not incorporated into the hash.
|
|
|
|
The step size used in the hash table is computed via
|
|
@code{((hash * 17) & (size - 1)) | 1}, where @samp{hash} is the hash
|
|
value, and @samp{size} is the size of the hash table. The step size
|
|
is used to find the next candidate slot when handling a hash
|
|
collision.
|
|
|
|
The names of C@t{++} symbols in the hash table are canonicalized. We
|
|
don't currently have a simple description of the canonicalization
|
|
algorithm; if you intend to create new index sections, you must read
|
|
the code.
|
|
|
|
@item
|
|
The constant pool. This is simply a bunch of bytes. It is organized
|
|
so that alignment is correct: CU vectors are stored first, followed by
|
|
strings.
|
|
|
|
A CU vector in the constant pool is a sequence of @code{offset_type}
|
|
values. The first value is the number of CU indices in the vector.
|
|
Each subsequent value is the index and symbol attributes of a CU in
|
|
the CU list. This element in the hash table is used to indicate which
|
|
CUs define the symbol and how the symbol is used.
|
|
See below for the format of each CU index+attributes entry.
|
|
|
|
A string in the constant pool is zero-terminated.
|
|
@end enumerate
|
|
|
|
Attributes were added to CU index values in @code{.gdb_index} version 7.
|
|
If a symbol has multiple uses within a CU then there is one
|
|
CU index+attributes value for each use.
|
|
|
|
The format of each CU index+attributes entry is as follows
|
|
(bit 0 = LSB):
|
|
|
|
@table @asis
|
|
|
|
@item Bits 0-23
|
|
This is the index of the CU in the CU list.
|
|
@item Bits 24-27
|
|
These bits are reserved for future purposes and must be zero.
|
|
@item Bits 28-30
|
|
The kind of the symbol in the CU.
|
|
|
|
@table @asis
|
|
@item 0
|
|
This value is reserved and should not be used.
|
|
By reserving zero the full @code{offset_type} value is backwards compatible
|
|
with previous versions of the index.
|
|
@item 1
|
|
The symbol is a type.
|
|
@item 2
|
|
The symbol is a variable or an enum value.
|
|
@item 3
|
|
The symbol is a function.
|
|
@item 4
|
|
Any other kind of symbol.
|
|
@item 5,6,7
|
|
These values are reserved.
|
|
@end table
|
|
|
|
@item Bit 31
|
|
This bit is zero if the value is global and one if it is static.
|
|
|
|
The determination of whether a symbol is global or static is complicated.
|
|
The authorative reference is the file @file{dwarf2read.c} in
|
|
@value{GDBN} sources.
|
|
|
|
@end table
|
|
|
|
This pseudo-code describes the computation of a symbol's kind and
|
|
global/static attributes in the index.
|
|
|
|
@smallexample
|
|
is_external = get_attribute (die, DW_AT_external);
|
|
language = get_attribute (cu_die, DW_AT_language);
|
|
switch (die->tag)
|
|
@{
|
|
case DW_TAG_typedef:
|
|
case DW_TAG_base_type:
|
|
case DW_TAG_subrange_type:
|
|
kind = TYPE;
|
|
is_static = 1;
|
|
break;
|
|
case DW_TAG_enumerator:
|
|
kind = VARIABLE;
|
|
is_static = (language != CPLUS && language != JAVA);
|
|
break;
|
|
case DW_TAG_subprogram:
|
|
kind = FUNCTION;
|
|
is_static = ! (is_external || language == ADA);
|
|
break;
|
|
case DW_TAG_constant:
|
|
kind = VARIABLE;
|
|
is_static = ! is_external;
|
|
break;
|
|
case DW_TAG_variable:
|
|
kind = VARIABLE;
|
|
is_static = ! is_external;
|
|
break;
|
|
case DW_TAG_namespace:
|
|
kind = TYPE;
|
|
is_static = 0;
|
|
break;
|
|
case DW_TAG_class_type:
|
|
case DW_TAG_interface_type:
|
|
case DW_TAG_structure_type:
|
|
case DW_TAG_union_type:
|
|
case DW_TAG_enumeration_type:
|
|
kind = TYPE;
|
|
is_static = (language != CPLUS && language != JAVA);
|
|
break;
|
|
default:
|
|
assert (0);
|
|
@}
|
|
@end smallexample
|
|
|
|
@include gpl.texi
|
|
|
|
@node GNU Free Documentation License
|
|
@appendix GNU Free Documentation License
|
|
@include fdl.texi
|
|
|
|
@node Concept Index
|
|
@unnumbered Concept Index
|
|
|
|
@printindex cp
|
|
|
|
@node Command and Variable Index
|
|
@unnumbered Command, Variable, and Function Index
|
|
|
|
@printindex fn
|
|
|
|
@tex
|
|
% I think something like @@colophon should be in texinfo. In the
|
|
% meantime:
|
|
\long\def\colophon{\hbox to0pt{}\vfill
|
|
\centerline{The body of this manual is set in}
|
|
\centerline{\fontname\tenrm,}
|
|
\centerline{with headings in {\bf\fontname\tenbf}}
|
|
\centerline{and examples in {\tt\fontname\tentt}.}
|
|
\centerline{{\it\fontname\tenit\/},}
|
|
\centerline{{\bf\fontname\tenbf}, and}
|
|
\centerline{{\sl\fontname\tensl\/}}
|
|
\centerline{are used for emphasis.}\vfill}
|
|
\page\colophon
|
|
% Blame: doc@@cygnus.com, 1991.
|
|
@end tex
|
|
|
|
@bye
|