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\input texinfo @c -*- Texinfo -*-
@setfilename binutils.info
@include config.texi
@ifinfo
@format
START-INFO-DIR-ENTRY
* Binutils: (binutils). The GNU binary utilities "ar", "objcopy",
"objdump", "nm", "nlmconv", "size", "readelf"
"strings", "strip", "ranlib" and "dlltool".
END-INFO-DIR-ENTRY
@end format
@end ifinfo
@ifinfo
Copyright @copyright{} 1991, 92, 93, 94, 95, 96, 97, 1998 Free Software Foundation, Inc.
Permission is granted to make and distribute verbatim copies of
this manual provided the copyright notice and this permission notice
are preserved on all copies.
@ignore
Permission is granted to process this file through TeX and print the
results, provided the printed document carries a copying permission
notice identical to this one except for the removal of this paragraph
(this paragraph not being relevant to the printed manual).
@end ignore
Permission is granted to copy and distribute modified versions of this
manual under the conditions for verbatim copying, provided also that
the entire resulting derived work is distributed under the terms of a
permission notice identical to this one.
Permission is granted to copy and distribute translations of this manual
into another language, under the above conditions for modified versions.
@end ifinfo
@synindex ky cp
@c
@c This file documents the GNU binary utilities "ar", "ld", "objcopy",
@c "objdump", "nm", "size", "strings", "strip", "readelf" and "ranlib".
@c
@c Copyright (C) 1991, 92, 93, 94, 95, 96, 97, 1998 Free Software Foundation, Inc.
@c
@c This text may be freely distributed under the terms of the GNU
@c General Public License.
@c
@setchapternewpage odd
@settitle @sc{gnu} Binary Utilities
@titlepage
@finalout
@title The @sc{gnu} Binary Utilities
@subtitle Version @value{VERSION}
@sp 1
@subtitle May 1993
@author Roland H. Pesch
@author Jeffrey M. Osier
@author Cygnus Support
@page
@tex
{\parskip=0pt \hfill Cygnus Support\par \hfill
\TeX{}info \texinfoversion\par }
@end tex
@vskip 0pt plus 1filll
Copyright @copyright{} 1991, 92, 93, 94, 95, 96, 97, 1998 Free Software Foundation, Inc.
Permission is granted to make and distribute verbatim copies of
this manual provided the copyright notice and this permission notice
are preserved on all copies.
Permission is granted to copy and distribute modified versions of this
manual under the conditions for verbatim copying, provided also that
the entire resulting derived work is distributed under the terms of a
permission notice identical to this one.
Permission is granted to copy and distribute translations of this manual
into another language, under the above conditions for modified versions.
@end titlepage
@node Top
@top Introduction
@cindex version
This brief manual contains preliminary documentation for the @sc{gnu} binary
utilities (collectively version @value{VERSION}):
@iftex
@table @code
@item ar
Create, modify, and extract from archives
@item nm
List symbols from object files
@item objcopy
Copy and translate object files
@item objdump
Display information from object files
@item ranlib
Generate index to archive contents
@item readelf
Display the contents of ELF format files.
@item size
List file section sizes and total size
@item strings
List printable strings from files
@item strip
Discard symbols
@item c++filt
Demangle encoded C++ symbols
@item addr2line
Convert addresses into file names and line numbers
@item nlmconv
Convert object code into a Netware Loadable Module
@item windres
Manipulate Windows resources
@item dlltool
Create the files needed to build and use Dynamic Link Libraries
@end table
@end iftex
@menu
* ar:: Create, modify, and extract from archives
* nm:: List symbols from object files
* objcopy:: Copy and translate object files
* objdump:: Display information from object files
* ranlib:: Generate index to archive contents
* readelf:: Display the contents of ELF format files.
* size:: List section sizes and total size
* strings:: List printable strings from files
* strip:: Discard symbols
* c++filt:: Filter to demangle encoded C++ symbols
* addr2line:: Convert addresses to file and line
* nlmconv:: Converts object code into an NLM
* windres:: Manipulate Windows resources
* dlltool:: Create files needed to build and use DLLs
* Selecting The Target System:: How these utilities determine the target.
* Reporting Bugs:: Reporting Bugs
* Index:: Index
@end menu
@node ar
@chapter ar
@kindex ar
@cindex archives
@cindex collections of files
@smallexample
ar [-]@var{p}[@var{mod} [@var{relpos}]] @var{archive} [@var{member}@dots{}]
ar -M [ <mri-script ]
@end smallexample
The @sc{gnu} @code{ar} program creates, modifies, and extracts from
archives. An @dfn{archive} is a single file holding a collection of
other files in a structure that makes it possible to retrieve
the original individual files (called @dfn{members} of the archive).
The original files' contents, mode (permissions), timestamp, owner, and
group are preserved in the archive, and can be restored on
extraction.
@cindex name length
@sc{gnu} @code{ar} can maintain archives whose members have names of any
length; however, depending on how @code{ar} is configured on your
system, a limit on member-name length may be imposed for compatibility
with archive formats maintained with other tools. If it exists, the
limit is often 15 characters (typical of formats related to a.out) or 16
characters (typical of formats related to coff).
@cindex libraries
@code{ar} is considered a binary utility because archives of this sort
are most often used as @dfn{libraries} holding commonly needed
subroutines.
@cindex symbol index
@code{ar} creates an index to the symbols defined in relocatable
object modules in the archive when you specify the modifier @samp{s}.
Once created, this index is updated in the archive whenever @code{ar}
makes a change to its contents (save for the @samp{q} update operation).
An archive with such an index speeds up linking to the library, and
allows routines in the library to call each other without regard to
their placement in the archive.
You may use @samp{nm -s} or @samp{nm --print-armap} to list this index
table. If an archive lacks the table, another form of @code{ar} called
@code{ranlib} can be used to add just the table.
@cindex compatibility, @code{ar}
@cindex @code{ar} compatibility
@sc{gnu} @code{ar} is designed to be compatible with two different
facilities. You can control its activity using command-line options,
like the different varieties of @code{ar} on Unix systems; or, if you
specify the single command-line option @samp{-M}, you can control it
with a script supplied via standard input, like the MRI ``librarian''
program.
@menu
* ar cmdline:: Controlling @code{ar} on the command line
* ar scripts:: Controlling @code{ar} with a script
@end menu
@page
@node ar cmdline
@section Controlling @code{ar} on the command line
@smallexample
ar [-]@var{p}[@var{mod} [@var{relpos}]] @var{archive} [@var{member}@dots{}]
@end smallexample
@cindex Unix compatibility, @code{ar}
When you use @code{ar} in the Unix style, @code{ar} insists on at least two
arguments to execute: one keyletter specifying the @emph{operation}
(optionally accompanied by other keyletters specifying
@emph{modifiers}), and the archive name to act on.
Most operations can also accept further @var{member} arguments,
specifying particular files to operate on.
@sc{gnu} @code{ar} allows you to mix the operation code @var{p} and modifier
flags @var{mod} in any order, within the first command-line argument.
If you wish, you may begin the first command-line argument with a
dash.
@cindex operations on archive
The @var{p} keyletter specifies what operation to execute; it may be
any of the following, but you must specify only one of them:
@table @code
@item d
@cindex deleting from archive
@emph{Delete} modules from the archive. Specify the names of modules to
be deleted as @var{member}@dots{}; the archive is untouched if you
specify no files to delete.
If you specify the @samp{v} modifier, @code{ar} lists each module
as it is deleted.
@item m
@cindex moving in archive
Use this operation to @emph{move} members in an archive.
The ordering of members in an archive can make a difference in how
programs are linked using the library, if a symbol is defined in more
than one member.
If no modifiers are used with @code{m}, any members you name in the
@var{member} arguments are moved to the @emph{end} of the archive;
you can use the @samp{a}, @samp{b}, or @samp{i} modifiers to move them to a
specified place instead.
@item p
@cindex printing from archive
@emph{Print} the specified members of the archive, to the standard
output file. If the @samp{v} modifier is specified, show the member
name before copying its contents to standard output.
If you specify no @var{member} arguments, all the files in the archive are
printed.
@item q
@cindex quick append to archive
@emph{Quick append}; Historically, add the files @var{member}@dots{} to the end of
@var{archive}, without checking for replacement.
The modifiers @samp{a}, @samp{b}, and @samp{i} do @emph{not} affect this
operation; new members are always placed at the end of the archive.
The modifier @samp{v} makes @code{ar} list each file as it is appended.
Since the point of this operation is speed, the archive's symbol table
index is not updated, even if it already existed; you can use @samp{ar s} or
@code{ranlib} explicitly to update the symbol table index.
However, too many different systems assume quick append rebuilds the
index, so GNU ar implements @code{q} as a synonym for @code{r}.
@item r
@cindex replacement in archive
Insert the files @var{member}@dots{} into @var{archive} (with
@emph{replacement}). This operation differs from @samp{q} in that any
previously existing members are deleted if their names match those being
added.
If one of the files named in @var{member}@dots{} does not exist, @code{ar}
displays an error message, and leaves undisturbed any existing members
of the archive matching that name.
By default, new members are added at the end of the file; but you may
use one of the modifiers @samp{a}, @samp{b}, or @samp{i} to request
placement relative to some existing member.
The modifier @samp{v} used with this operation elicits a line of
output for each file inserted, along with one of the letters @samp{a} or
@samp{r} to indicate whether the file was appended (no old member
deleted) or replaced.
@item t
@cindex contents of archive
Display a @emph{table} listing the contents of @var{archive}, or those
of the files listed in @var{member}@dots{} that are present in the
archive. Normally only the member name is shown; if you also want to
see the modes (permissions), timestamp, owner, group, and size, you can
request that by also specifying the @samp{v} modifier.
If you do not specify a @var{member}, all files in the archive
are listed.
@cindex repeated names in archive
@cindex name duplication in archive
If there is more than one file with the same name (say, @samp{fie}) in
an archive (say @samp{b.a}), @samp{ar t b.a fie} lists only the
first instance; to see them all, you must ask for a complete
listing---in our example, @samp{ar t b.a}.
@c WRS only; per Gumby, this is implementation-dependent, and in a more
@c recent case in fact works the other way.
@item x
@cindex extract from archive
@emph{Extract} members (named @var{member}) from the archive. You can
use the @samp{v} modifier with this operation, to request that
@code{ar} list each name as it extracts it.
If you do not specify a @var{member}, all files in the archive
are extracted.
@end table
A number of modifiers (@var{mod}) may immediately follow the @var{p}
keyletter, to specify variations on an operation's behavior:
@table @code
@item a
@cindex relative placement in archive
Add new files @emph{after} an existing member of the
archive. If you use the modifier @samp{a}, the name of an existing archive
member must be present as the @var{relpos} argument, before the
@var{archive} specification.
@item b
Add new files @emph{before} an existing member of the
archive. If you use the modifier @samp{b}, the name of an existing archive
member must be present as the @var{relpos} argument, before the
@var{archive} specification. (same as @samp{i}).
@item c
@cindex creating archives
@emph{Create} the archive. The specified @var{archive} is always
created if it did not exist, when you request an update. But a warning is
issued unless you specify in advance that you expect to create it, by
using this modifier.
@item f
Truncate names in the archive. @sc{gnu} @code{ar} will normally permit file
names of any length. This will cause it to create archives which are
not compatible with the native @code{ar} program on some systems. If
this is a concern, the @samp{f} modifier may be used to truncate file
names when putting them in the archive.
@item i
Insert new files @emph{before} an existing member of the
archive. If you use the modifier @samp{i}, the name of an existing archive
member must be present as the @var{relpos} argument, before the
@var{archive} specification. (same as @samp{b}).
@item l
This modifier is accepted but not used.
@c whaffor ar l modifier??? presumably compat; with
@c what???---doc@@cygnus.com, 25jan91
@item o
@cindex dates in archive
Preserve the @emph{original} dates of members when extracting them. If
you do not specify this modifier, files extracted from the archive
are stamped with the time of extraction.
@item s
@cindex writing archive index
Write an object-file index into the archive, or update an existing one,
even if no other change is made to the archive. You may use this modifier
flag either with any operation, or alone. Running @samp{ar s} on an
archive is equivalent to running @samp{ranlib} on it.
@item S
@cindex not writing archive index
Do not generate an archive symbol table. This can speed up building a
large library in several steps. The resulting archive can not be used
with the linker. In order to build a symbol table, you must omit the
@samp{S} modifier on the last execution of @samp{ar}, or you must run
@samp{ranlib} on the archive.
@item u
@cindex updating an archive
Normally, @samp{ar r}@dots{} inserts all files
listed into the archive. If you would like to insert @emph{only} those
of the files you list that are newer than existing members of the same
names, use this modifier. The @samp{u} modifier is allowed only for the
operation @samp{r} (replace). In particular, the combination @samp{qu} is
not allowed, since checking the timestamps would lose any speed
advantage from the operation @samp{q}.
@item v
This modifier requests the @emph{verbose} version of an operation. Many
operations display additional information, such as filenames processed,
when the modifier @samp{v} is appended.
@item V
This modifier shows the version number of @code{ar}.
@end table
@node ar scripts
@section Controlling @code{ar} with a script
@smallexample
ar -M [ <@var{script} ]
@end smallexample
@cindex MRI compatibility, @code{ar}
@cindex scripts, @code{ar}
If you use the single command-line option @samp{-M} with @code{ar}, you
can control its operation with a rudimentary command language. This
form of @code{ar} operates interactively if standard input is coming
directly from a terminal. During interactive use, @code{ar} prompts for
input (the prompt is @samp{AR >}), and continues executing even after
errors. If you redirect standard input to a script file, no prompts are
issued, and @code{ar} abandons execution (with a nonzero exit code)
on any error.
The @code{ar} command language is @emph{not} designed to be equivalent
to the command-line options; in fact, it provides somewhat less control
over archives. The only purpose of the command language is to ease the
transition to @sc{gnu} @code{ar} for developers who already have scripts
written for the MRI ``librarian'' program.
The syntax for the @code{ar} command language is straightforward:
@itemize @bullet
@item
commands are recognized in upper or lower case; for example, @code{LIST}
is the same as @code{list}. In the following descriptions, commands are
shown in upper case for clarity.
@item
a single command may appear on each line; it is the first word on the
line.
@item
empty lines are allowed, and have no effect.
@item
comments are allowed; text after either of the characters @samp{*}
or @samp{;} is ignored.
@item
Whenever you use a list of names as part of the argument to an @code{ar}
command, you can separate the individual names with either commas or
blanks. Commas are shown in the explanations below, for clarity.
@item
@samp{+} is used as a line continuation character; if @samp{+} appears
at the end of a line, the text on the following line is considered part
of the current command.
@end itemize
Here are the commands you can use in @code{ar} scripts, or when using
@code{ar} interactively. Three of them have special significance:
@code{OPEN} or @code{CREATE} specify a @dfn{current archive}, which is
a temporary file required for most of the other commands.
@code{SAVE} commits the changes so far specified by the script. Prior
to @code{SAVE}, commands affect only the temporary copy of the current
archive.
@table @code
@item ADDLIB @var{archive}
@itemx ADDLIB @var{archive} (@var{module}, @var{module}, @dots{} @var{module})
Add all the contents of @var{archive} (or, if specified, each named
@var{module} from @var{archive}) to the current archive.
Requires prior use of @code{OPEN} or @code{CREATE}.
@item ADDMOD @var{member}, @var{member}, @dots{} @var{member}
@c FIXME! w/Replacement?? If so, like "ar r @var{archive} @var{names}"
@c else like "ar q..."
Add each named @var{member} as a module in the current archive.
Requires prior use of @code{OPEN} or @code{CREATE}.
@item CLEAR
Discard the contents of the current archive, canceling the effect of
any operations since the last @code{SAVE}. May be executed (with no
effect) even if no current archive is specified.
@item CREATE @var{archive}
Creates an archive, and makes it the current archive (required for many
other commands). The new archive is created with a temporary name; it
is not actually saved as @var{archive} until you use @code{SAVE}.
You can overwrite existing archives; similarly, the contents of any
existing file named @var{archive} will not be destroyed until @code{SAVE}.
@item DELETE @var{module}, @var{module}, @dots{} @var{module}
Delete each listed @var{module} from the current archive; equivalent to
@samp{ar -d @var{archive} @var{module} @dots{} @var{module}}.
Requires prior use of @code{OPEN} or @code{CREATE}.
@item DIRECTORY @var{archive} (@var{module}, @dots{} @var{module})
@itemx DIRECTORY @var{archive} (@var{module}, @dots{} @var{module}) @var{outputfile}
List each named @var{module} present in @var{archive}. The separate
command @code{VERBOSE} specifies the form of the output: when verbose
output is off, output is like that of @samp{ar -t @var{archive}
@var{module}@dots{}}. When verbose output is on, the listing is like
@samp{ar -tv @var{archive} @var{module}@dots{}}.
Output normally goes to the standard output stream; however, if you
specify @var{outputfile} as a final argument, @code{ar} directs the
output to that file.
@item END
Exit from @code{ar}, with a @code{0} exit code to indicate successful
completion. This command does not save the output file; if you have
changed the current archive since the last @code{SAVE} command, those
changes are lost.
@item EXTRACT @var{module}, @var{module}, @dots{} @var{module}
Extract each named @var{module} from the current archive, writing them
into the current directory as separate files. Equivalent to @samp{ar -x
@var{archive} @var{module}@dots{}}.
Requires prior use of @code{OPEN} or @code{CREATE}.
@ignore
@c FIXME Tokens but no commands???
@item FULLDIR
@item HELP
@end ignore
@item LIST
Display full contents of the current archive, in ``verbose'' style
regardless of the state of @code{VERBOSE}. The effect is like @samp{ar
tv @var{archive}}). (This single command is a @sc{gnu} @code{ld}
enhancement, rather than present for MRI compatibility.)
Requires prior use of @code{OPEN} or @code{CREATE}.
@item OPEN @var{archive}
Opens an existing archive for use as the current archive (required for
many other commands). Any changes as the result of subsequent commands
will not actually affect @var{archive} until you next use @code{SAVE}.
@item REPLACE @var{module}, @var{module}, @dots{} @var{module}
In the current archive, replace each existing @var{module} (named in
the @code{REPLACE} arguments) from files in the current working directory.
To execute this command without errors, both the file, and the module in
the current archive, must exist.
Requires prior use of @code{OPEN} or @code{CREATE}.
@item VERBOSE
Toggle an internal flag governing the output from @code{DIRECTORY}.
When the flag is on, @code{DIRECTORY} output matches output from
@samp{ar -tv }@dots{}.
@item SAVE
Commit your changes to the current archive, and actually save it as a
file with the name specified in the last @code{CREATE} or @code{OPEN}
command.
Requires prior use of @code{OPEN} or @code{CREATE}.
@end table
@iftex
@node ld
@chapter ld
@cindex linker
@kindex ld
The @sc{gnu} linker @code{ld} is now described in a separate manual.
@xref{Top,, Overview,, Using LD: the @sc{gnu} linker}.
@end iftex
@node nm
@chapter nm
@cindex symbols
@kindex nm
@smallexample
nm [ -a | --debug-syms ] [ -g | --extern-only ]
[ -B ] [ -C | --demangle ] [ -D | --dynamic ]
[ -s | --print-armap ] [ -A | -o | --print-file-name ]
[ -n | -v | --numeric-sort ] [ -p | --no-sort ]
[ -r | --reverse-sort ] [ --size-sort ] [ -u | --undefined-only ]
[ -t @var{radix} | --radix=@var{radix} ] [ -P | --portability ]
[ --target=@var{bfdname} ] [ -f @var{format} | --format=@var{format} ]
[ --defined-only ] [-l | --line-numbers ]
[ --no-demangle ] [ -V | --version ] [ --help ] [ @var{objfile}@dots{} ]
@end smallexample
@sc{gnu} @code{nm} lists the symbols from object files @var{objfile}@dots{}.
If no object files are listed as arguments, @code{nm} assumes
@file{a.out}.
For each symbol, @code{nm} shows:
@itemize @bullet
@item
The symbol value, in the radix selected by options (see below), or
hexadecimal by default.
@item
The symbol type. At least the following types are used; others are, as
well, depending on the object file format. If lowercase, the symbol is
local; if uppercase, the symbol is global (external).
@c Some more detail on exactly what these symbol types are used for
@c would be nice.
@table @code
@item A
The symbol's value is absolute, and will not be changed by further
linking.
@item B
The symbol is in the uninitialized data section (known as BSS).
@item C
The symbol is common. Common symbols are uninitialized data. When
linking, multiple common symbols may appear with the same name. If the
symbol is defined anywhere, the common symbols are treated as undefined
references. For more details on common symbols, see the discussion of
--warn-common in @ref{Options,,Linker options,ld.info,The GNU linker}.
@item D
The symbol is in the initialized data section.
@item G
The symbol is in an initialized data section for small objects. Some
object file formats permit more efficient access to small data objects,
such as a global int variable as opposed to a large global array.
@item I
The symbol is an indirect reference to another symbol. This is a GNU
extension to the a.out object file format which is rarely used.
@item N
The symbol is a debugging symbol.
@item R
The symbol is in a read only data section.
@item S
The symbol is in an uninitialized data section for small objects.
@item T
The symbol is in the text (code) section.
@item U
The symbol is undefined.
@item W
The symbol is weak. When a weak defined symbol is linked with a normal
defined symbol, the normal defined symbol is used with no error. When a
weak undefined symbol is linked and the symbol is not defined, the value
of the weak symbol becomes zero with no error.
@item -
The symbol is a stabs symbol in an a.out object file. In this case, the
next values printed are the stabs other field, the stabs desc field, and
the stab type. Stabs symbols are used to hold debugging information;
for more information, see @ref{Top,Stabs,Stabs Overview,stabs.info, The
``stabs'' debug format}.
@item ?
The symbol type is unknown, or object file format specific.
@end table
@item
The symbol name.
@end itemize
The long and short forms of options, shown here as alternatives, are
equivalent.
@table @code
@item -A
@itemx -o
@itemx --print-file-name
@cindex input file name
@cindex file name
@cindex source file name
Precede each symbol by the name of the input file (or archive element)
in which it was found, rather than identifying the input file once only,
before all of its symbols.
@item -a
@itemx --debug-syms
@cindex debugging symbols
Display all symbols, even debugger-only symbols; normally these are not
listed.
@item -B
@cindex @code{nm} format
@cindex @code{nm} compatibility
The same as @samp{--format=bsd} (for compatibility with the MIPS @code{nm}).
@item -C
@itemx --demangle
@cindex demangling in nm
Decode (@dfn{demangle}) low-level symbol names into user-level names.
Besides removing any initial underscore prepended by the system, this
makes C++ function names readable. @xref{c++filt}, for more information
on demangling.
@item --no-demangle
Do not demangle low-level symbol names. This is the default.
@item -D
@itemx --dynamic
@cindex dynamic symbols
Display the dynamic symbols rather than the normal symbols. This is
only meaningful for dynamic objects, such as certain types of shared
libraries.
@item -f @var{format}
@itemx --format=@var{format}
@cindex @code{nm} format
@cindex @code{nm} compatibility
Use the output format @var{format}, which can be @code{bsd},
@code{sysv}, or @code{posix}. The default is @code{bsd}.
Only the first character of @var{format} is significant; it can be
either upper or lower case.
@item -g
@itemx --extern-only
@cindex external symbols
Display only external symbols.
@item -l
@itemx --line-numbers
@cindex symbol line numbers
For each symbol, use debugging information to try to find a filename and
line number. For a defined symbol, look for the line number of the
address of the symbol. For an undefined symbol, look for the line
number of a relocation entry which refers to the symbol. If line number
information can be found, print it after the other symbol information.
@item -n
@itemx -v
@itemx --numeric-sort
Sort symbols numerically by their addresses, rather than alphabetically
by their names.
@item -p
@itemx --no-sort
@cindex sorting symbols
Do not bother to sort the symbols in any order; print them in the order
encountered.
@item -P
@itemx --portability
Use the POSIX.2 standard output format instead of the default format.
Equivalent to @samp{-f posix}.
@item -s
@itemx --print-armap
@cindex symbol index, listing
When listing symbols from archive members, include the index: a mapping
(stored in the archive by @code{ar} or @code{ranlib}) of which modules
contain definitions for which names.
@item -r
@itemx --reverse-sort
Reverse the order of the sort (whether numeric or alphabetic); let the
last come first.
@item --size-sort
Sort symbols by size. The size is computed as the difference between
the value of the symbol and the value of the symbol with the next higher
value. The size of the symbol is printed, rather than the value.
@item -t @var{radix}
@itemx --radix=@var{radix}
Use @var{radix} as the radix for printing the symbol values. It must be
@samp{d} for decimal, @samp{o} for octal, or @samp{x} for hexadecimal.
@item --target=@var{bfdname}
@cindex object code format
Specify an object code format other than your system's default format.
@xref{Target Selection}, for more information.
@item -u
@itemx --undefined-only
@cindex external symbols
@cindex undefined symbols
Display only undefined symbols (those external to each object file).
@item --defined-only
@cindex external symbols
@cindex undefined symbols
Display only defined symbols for each object file.
@item -V
@itemx --version
Show the version number of @code{nm} and exit.
@item --help
Show a summary of the options to @code{nm} and exit.
@end table
@node objcopy
@chapter objcopy
@smallexample
objcopy [ -F @var{bfdname} | --target=@var{bfdname} ]
[ -I @var{bfdname} | --input-target=@var{bfdname} ]
[ -O @var{bfdname} | --output-target=@var{bfdname} ]
[ -S | --strip-all ] [ -g | --strip-debug ]
[ -K @var{symbolname} | --keep-symbol=@var{symbolname} ]
[ -N @var{symbolname} | --strip-symbol=@var{symbolname} ]
[ -L @var{symbolname} | --localize-symbol=@var{symbolname} ]
[ -W @var{symbolname} | --weaken-symbol=@var{symbolname} ]
[ -x | --discard-all ] [ -X | --discard-locals ]
[ -b @var{byte} | --byte=@var{byte} ]
[ -i @var{interleave} | --interleave=@var{interleave} ]
[ -R @var{sectionname} | --remove-section=@var{sectionname} ]
[ -p | --preserve-dates ] [ --debugging ]
[ --gap-fill=@var{val} ] [ --pad-to=@var{address} ]
[ --set-start=@var{val} ] [ --adjust-start=@var{incr} ]
[ --change-addresses=@var{incr} ]
[ --change-section-address=@var{section}@{=,+,-@}@var{val} ]
[ --change-section-lma=@var{section}@{=,+,-@}@var{val} ]
[ --change-section-vma=@var{section}@{=,+,-@}@var{val} ]
[ --change-warnings ] [ --no-change-warnings ]
[ --set-section-flags=@var{section}=@var{flags} ]
[ --add-section=@var{sectionname}=@var{filename} ]
[ --change-leading-char ] [ --remove-leading-char ]
[ --weaken ]
[ -v | --verbose ] [ -V | --version ] [ --help ]
@var{infile} [@var{outfile}]
@end smallexample
The @sc{gnu} @code{objcopy} utility copies the contents of an object
file to another. @code{objcopy} uses the @sc{gnu} @sc{bfd} Library to
read and write the object files. It can write the destination object
file in a format different from that of the source object file. The
exact behavior of @code{objcopy} is controlled by command-line options.
@code{objcopy} creates temporary files to do its translations and
deletes them afterward. @code{objcopy} uses @sc{bfd} to do all its
translation work; it has access to all the formats described in @sc{bfd}
and thus is able to recognize most formats without being told
explicitly. @xref{BFD,,BFD,ld.info,Using LD}.
@code{objcopy} can be used to generate S-records by using an output
target of @samp{srec} (e.g., use @samp{-O srec}).
@code{objcopy} can be used to generate a raw binary file by using an
output target of @samp{binary} (e.g., use @samp{-O binary}). When
@code{objcopy} generates a raw binary file, it will essentially produce
a memory dump of the contents of the input object file. All symbols and
relocation information will be discarded. The memory dump will start at
the load address of the lowest section copied into the output file.
When generating an S-record or a raw binary file, it may be helpful to
use @samp{-S} to remove sections containing debugging information. In
some cases @samp{-R} will be useful to remove sections which contain
information which is not needed by the binary file.
@table @code
@item @var{infile}
@itemx @var{outfile}
The source and output files, respectively.
If you do not specify @var{outfile}, @code{objcopy} creates a
temporary file and destructively renames the result with
the name of @var{infile}.
@item -I @var{bfdname}
@itemx --input-target=@var{bfdname}
Consider the source file's object format to be @var{bfdname}, rather than
attempting to deduce it. @xref{Target Selection}, for more information.
@item -O @var{bfdname}
@itemx --output-target=@var{bfdname}
Write the output file using the object format @var{bfdname}.
@xref{Target Selection}, for more information.
@item -F @var{bfdname}
@itemx --target=@var{bfdname}
Use @var{bfdname} as the object format for both the input and the output
file; i.e., simply transfer data from source to destination with no
translation. @xref{Target Selection}, for more information.
@item -R @var{sectionname}
@itemx --remove-section=@var{sectionname}
Remove any section named @var{sectionname} from the output file. This
option may be given more than once. Note that using this option
inappropriately may make the output file unusable.
@item -S
@itemx --strip-all
Do not copy relocation and symbol information from the source file.
@item -g
@itemx --strip-debug
Do not copy debugging symbols from the source file.
@item --strip-unneeded
Strip all symbols that are not needed for relocation processing.
@item -K @var{symbolname}
@itemx --keep-symbol=@var{symbolname}
Copy only symbol @var{symbolname} from the source file. This option may
be given more than once.
@item -N @var{symbolname}
@itemx --strip-symbol=@var{symbolname}
Do not copy symbol @var{symbolname} from the source file. This option
may be given more than once.
@item -L @var{symbolname}
@itemx --localize-symbol=@var{symbolname}
Make symbol @var{symbolname} local to the file, so that it is not
visible externally. This option may be given more than once.
@item -W @var{symbolname}
@itemx --weaken-symbol=@var{symbolname}
Make symbol @var{symbolname} weak. This option may be given more than once.
@item -x
@itemx --discard-all
Do not copy non-global symbols from the source file.
@c FIXME any reason to prefer "non-global" to "local" here?
@item -X
@itemx --discard-locals
Do not copy compiler-generated local symbols.
(These usually start with @samp{L} or @samp{.}.)
@item -b @var{byte}
@itemx --byte=@var{byte}
Keep only every @var{byte}th byte of the input file (header data is not
affected). @var{byte} can be in the range from 0 to @var{interleave}-1,
where @var{interleave} is given by the @samp{-i} or @samp{--interleave}
option, or the default of 4. This option is useful for creating files
to program @sc{rom}. It is typically used with an @code{srec} output
target.
@item -i @var{interleave}
@itemx --interleave=@var{interleave}
Only copy one out of every @var{interleave} bytes. Select which byte to
copy with the @var{-b} or @samp{--byte} option. The default is 4.
@code{objcopy} ignores this option if you do not specify either @samp{-b} or
@samp{--byte}.
@item -p
@itemx --preserve-dates
Set the access and modification dates of the output file to be the same
as those of the input file.
@item --debugging
Convert debugging information, if possible. This is not the default
because only certain debugging formats are supported, and the
conversion process can be time consuming.
@item --gap-fill @var{val}
Fill gaps between sections with @var{val}. This operation applies to
the @emph{load address} (LMA) of the sections. It is done by increasing
the size of the section with the lower address, and filling in the extra
space created with @var{val}.
@item --pad-to @var{address}
Pad the output file up to the load address @var{address}. This is
done by increasing the size of the last section. The extra space is
filled in with the value specified by @samp{--gap-fill} (default zero).
@item --set-start @var{val}
Set the address of the new file to @var{val}. Not all object file
formats support setting the start address.
@item --change-start @var{incr}
@itemx --adjust-start @var{incr}
@cindex changing start address
Change the start address by adding @var{incr}. Not all object file
formats support setting the start address.
@item --change-addresses @var{incr}
@itemx --adjust-vma @var{incr}
@cindex changing object addresses
Change the VMA and LMA addresses of all sections, as well as the start
address, by adding @var{incr}. Some object file formats do not permit
section addresses to be changed arbitrarily. Note that this does not
relocate the sections; if the program expects sections to be loaded at a
certain address, and this option is used to change the sections such
that they are loaded at a different address, the program may fail.
@item --change-section-address @var{section}@{=,+,-@}@var{val}
@itemx --adjust-section-vma @var{section}@{=,+,-@}@var{val}
@cindex changing section address
Set or change both the VMA address and the LMA address of the named
@var{section}. If @samp{=} is used, the section address is set to
@var{val}. Otherwise, @var{val} is added to or subtracted from the
section address. See the comments under @samp{--change-addresses},
above. If @var{section} does not exist in the input file, a warning will
be issued, unless @samp{--no-change-warnings} is used.
@item --change-section-lma @var{section}@{=,+,-@}@var{val}
@cindex changing section LMA
Set or change the LMA address of the named @var{section}. The LMA
address is the address where the section will be loaded into memory at
program load time. Normally this is the same as the VMA address, which
is the address of the section at program run time, but on some systems,
especially those where a program is held in ROM, the two can be
different. If @samp{=} is used, the section address is set to
@var{val}. Otherwise, @var{val} is added to or subtracted from the
section address. See the comments under @samp{--change-addresses},
above. If @var{section} does not exist in the input file, a warning
will be issued, unless @samp{--no-change-warnings} is used.
@item --change-section-vma @var{section}@{=,+,-@}@var{val}
@cindex changing section VMA
Set or change the VMA address of the named @var{section}. The VMA
address is the address where the section will be located once the
program has started executing. Normally this is the same as the LMA
address, which is the address where the section will be loaded into
memory, but on some systems, especially those where a program is held in
ROM, the two can be different. If @samp{=} is used, the section address
is set to @var{val}. Otherwise, @var{val} is added to or subtracted
from the section address. See the comments under
@samp{--change-addresses}, above. If @var{section} does not exist in
the input file, a warning will be issued, unless
@samp{--no-change-warnings} is used.
@item --change-warnings
@itemx --adjust-warnings
If @samp{--change-section-address} or @samp{--change-section-lma} or
@samp{--change-section-vma} is used, and the named section does not
exist, issue a warning. This is the default.
@item --no-change-warnings
@itemx --no-adjust-warnings
Do not issue a warning if @samp{--change-section-address} or
@samp{--adjust-section-lma} or @samp{--adjust-section-vma} is used, even
if the named section does not exist.
@item --set-section-flags @var{section}=@var{flags}
Set the flags for the named section. The @var{flags} argument is a
comma separated string of flag names. The recognized names are
@samp{alloc}, @samp{contents}, @samp{load}, @samp{readonly},
@samp{code}, @samp{data}, and @samp{rom}. You can set the
@samp{contents} flag for a section which does not have contents, but it
is not meaningful to clear the @samp{contents} flag of a section which
does have contents--just remove the section instead. Not all flags are
meaningful for all object file formats.
@item --add-section @var{sectionname}=@var{filename}
Add a new section named @var{sectionname} while copying the file. The
contents of the new section are taken from the file @var{filename}. The
size of the section will be the size of the file. This option only
works on file formats which can support sections with arbitrary names.
@item --change-leading-char
Some object file formats use special characters at the start of
symbols. The most common such character is underscore, which compilers
often add before every symbol. This option tells @code{objcopy} to
change the leading character of every symbol when it converts between
object file formats. If the object file formats use the same leading
character, this option has no effect. Otherwise, it will add a
character, or remove a character, or change a character, as
appropriate.
@item --remove-leading-char
If the first character of a global symbol is a special symbol leading
character used by the object file format, remove the character. The
most common symbol leading character is underscore. This option will
remove a leading underscore from all global symbols. This can be useful
if you want to link together objects of different file formats with
different conventions for symbol names. This is different from
@code{--change-leading-char} because it always changes the symbol name
when appropriate, regardless of the object file format of the output
file.
@item --weaken
Change all global symbols in the file to be weak. This can be useful
when building an object which will be linked against other objects using
the @code{-R} option to the linker. This option is only effective when
using an object file format which supports weak symbols.
@item -V
@itemx --version
Show the version number of @code{objcopy}.
@item -v
@itemx --verbose
Verbose output: list all object files modified. In the case of
archives, @samp{objcopy -V} lists all members of the archive.
@item --help
Show a summary of the options to @code{objcopy}.
@end table
@node objdump
@chapter objdump
@cindex object file information
@kindex objdump
@smallexample
objdump [ -a | --archive-headers ]
[ -b @var{bfdname} | --target=@var{bfdname} ] [ --debugging ]
[ -C | --demangle ] [ -d | --disassemble ]
[ -D | --disassemble-all ] [ --disassemble-zeroes ]
[ -EB | -EL | --endian=@{big | little @} ]
[ -f | --file-headers ]
[ -h | --section-headers | --headers ] [ -i | --info ]
[ -j @var{section} | --section=@var{section} ]
[ -l | --line-numbers ] [ -S | --source ]
[ -m @var{machine} | --architecture=@var{machine} ]
[ -p | --private-headers ]
[ -r | --reloc ] [ -R | --dynamic-reloc ]
[ -s | --full-contents ] [ --stabs ]
[ -t | --syms ] [ -T | --dynamic-syms ] [ -x | --all-headers ]
[ -w | --wide ] [ --start-address=@var{address} ]
[ --stop-address=@var{address} ]
[ --prefix-addresses] [ --[no-]show-raw-insn ]
[ --adjust-vma=@var{offset} ]
[ --version ] [ --help ]
@var{objfile}@dots{}
@end smallexample
@code{objdump} displays information about one or more object files.
The options control what particular information to display. This
information is mostly useful to programmers who are working on the
compilation tools, as opposed to programmers who just want their
program to compile and work.
@var{objfile}@dots{} are the object files to be examined. When you
specify archives, @code{objdump} shows information on each of the member
object files.
The long and short forms of options, shown here as alternatives, are
equivalent. At least one option besides @samp{-l} must be given.
@table @code
@item -a
@itemx --archive-header
@cindex archive headers
If any of the @var{objfile} files are archives, display the archive
header information (in a format similar to @samp{ls -l}). Besides the
information you could list with @samp{ar tv}, @samp{objdump -a} shows
the object file format of each archive member.
@item --adjust-vma=@var{offset}
@cindex section addresses in objdump
@cindex VMA in objdump
When dumping information, first add @var{offset} to all the section
addresses. This is useful if the section addresses do not correspond to
the symbol table, which can happen when putting sections at particular
addresses when using a format which can not represent section addresses,
such as a.out.
@item -b @var{bfdname}
@itemx --target=@var{bfdname}
@cindex object code format
Specify that the object-code format for the object files is
@var{bfdname}. This option may not be necessary; @var{objdump} can
automatically recognize many formats.
For example,
@example
objdump -b oasys -m vax -h fu.o
@end example
@noindent
displays summary information from the section headers (@samp{-h}) of
@file{fu.o}, which is explicitly identified (@samp{-m}) as a VAX object
file in the format produced by Oasys compilers. You can list the
formats available with the @samp{-i} option.
@xref{Target Selection}, for more information.
@item -C
@itemx --demangle
@cindex demangling in objdump
Decode (@dfn{demangle}) low-level symbol names into user-level names.
Besides removing any initial underscore prepended by the system, this
makes C++ function names readable. @xref{c++filt}, for more information
on demangling.
@item --debugging
Display debugging information. This attempts to parse debugging
information stored in the file and print it out using a C like syntax.
Only certain types of debugging information have been implemented.
@item -d
@itemx --disassemble
@cindex disassembling object code
@cindex machine instructions
Display the assembler mnemonics for the machine instructions from
@var{objfile}. This option only disassembles those sections which are
expected to contain instructions.
@item -D
@itemx --disassemble-all
Like @samp{-d}, but disassemble the contents of all sections, not just
those expected to contain instructions.
@item --prefix-addresses
When disassembling, print the complete address on each line. This is
the older disassembly format.
@item --disassemble-zeroes
Normally the disassembly output will skip blocks of zeroes. This
option directs the disassembler to disassemble those blocks, just like
any other data.
@item -EB
@itemx -EL
@itemx --endian=@{big|little@}
@cindex endianness
@cindex disassembly endianness
Specify the endianness of the object files. This only affects
disassembly. This can be useful when disassembling a file format which
does not describe endianness information, such as S-records.
@item -f
@itemx --file-header
@cindex object file header
Display summary information from the overall header of
each of the @var{objfile} files.
@item -h
@itemx --section-header
@itemx --header
@cindex section headers
Display summary information from the section headers of the
object file.
File segments may be relocated to nonstandard addresses, for example by
using the @samp{-Ttext}, @samp{-Tdata}, or @samp{-Tbss} options to
@code{ld}. However, some object file formats, such as a.out, do not
store the starting address of the file segments. In those situations,
although @code{ld} relocates the sections correctly, using @samp{objdump
-h} to list the file section headers cannot show the correct addresses.
Instead, it shows the usual addresses, which are implicit for the
target.
@item --help
Print a summary of the options to @code{objdump} and exit.
@item -i
@itemx --info
@cindex architectures available
@cindex object formats available
Display a list showing all architectures and object formats available
for specification with @samp{-b} or @samp{-m}.
@item -j @var{name}
@itemx --section=@var{name}
@cindex section information
Display information only for section @var{name}.
@item -l
@itemx --line-numbers
@cindex source filenames for object files
Label the display (using debugging information) with the filename and
source line numbers corresponding to the object code or relocs shown.
Only useful with @samp{-d}, @samp{-D}, or @samp{-r}.
@item -m @var{machine}
@itemx --architecture=@var{machine}
@cindex architecture
@cindex disassembly architecture
Specify the architecture to use when disassembling object files. This
can be useful when disassembling object files which do not describe
architecture information, such as S-records. You can list the available
architectures with the @samp{-i} option.
@item -p
@itemx --private-headers
Print information that is specific to the object file format. The exact
information printed depends upon the object file format. For some
object file formats, no additional information is printed.
@item -r
@itemx --reloc
@cindex relocation entries, in object file
Print the relocation entries of the file. If used with @samp{-d} or
@samp{-D}, the relocations are printed interspersed with the
disassembly.
@item -R
@itemx --dynamic-reloc
@cindex dynamic relocation entries, in object file
Print the dynamic relocation entries of the file. This is only
meaningful for dynamic objects, such as certain types of shared
libraries.
@item -s
@itemx --full-contents
@cindex sections, full contents
@cindex object file sections
Display the full contents of any sections requested.
@item -S
@itemx --source
@cindex source disassembly
@cindex disassembly, with source
Display source code intermixed with disassembly, if possible. Implies
@samp{-d}.
@item --show-raw-insn
When disassembling instructions, print the instruction in hex as well as
in symbolic form. This is the default except when
@code{--prefix-addresses} is used.
@item --no-show-raw-insn
When disassembling instructions, do not print the instruction bytes.
This is the default when @code{--prefix-addresses} is used.
@item --stabs
@cindex stab
@cindex .stab
@cindex debug symbols
@cindex ELF object file format
Display the full contents of any sections requested. Display the
contents of the .stab and .stab.index and .stab.excl sections from an
ELF file. This is only useful on systems (such as Solaris 2.0) in which
@code{.stab} debugging symbol-table entries are carried in an ELF
section. In most other file formats, debugging symbol-table entries are
interleaved with linkage symbols, and are visible in the @samp{--syms}
output. For more information on stabs symbols, see @ref{Top,Stabs,Stabs
Overview,stabs.info, The ``stabs'' debug format}.
@item --start-address=@var{address}
@cindex start-address
Start displaying data at the specified address. This affects the output
of the @code{-d}, @code{-r} and @code{-s} options.
@item --stop-address=@var{address}
@cindex stop-address
Stop displaying data at the specified address. This affects the output
of the @code{-d}, @code{-r} and @code{-s} options.
@item -t
@itemx --syms
@cindex symbol table entries, printing
Print the symbol table entries of the file.
This is similar to the information provided by the @samp{nm} program.
@item -T
@itemx --dynamic-syms
@cindex dynamic symbol table entries, printing
Print the dynamic symbol table entries of the file. This is only
meaningful for dynamic objects, such as certain types of shared
libraries. This is similar to the information provided by the @samp{nm}
program when given the @samp{-D} (@samp{--dynamic}) option.
@item --version
Print the version number of @code{objdump} and exit.
@item -x
@itemx --all-header
@cindex all header information, object file
@cindex header information, all
Display all available header information, including the symbol table and
relocation entries. Using @samp{-x} is equivalent to specifying all of
@samp{-a -f -h -r -t}.
@item -w
@itemx --wide
@cindex wide output, printing
Format some lines for output devices that have more than 80 columns.
@end table
@node ranlib
@chapter ranlib
@kindex ranlib
@cindex archive contents
@cindex symbol index
@smallexample
ranlib [-vV] @var{archive}
@end smallexample
@code{ranlib} generates an index to the contents of an archive and
stores it in the archive. The index lists each symbol defined by a
member of an archive that is a relocatable object file.
You may use @samp{nm -s} or @samp{nm --print-armap} to list this index.
An archive with such an index speeds up linking to the library and
allows routines in the library to call each other without regard to
their placement in the archive.
The @sc{gnu} @code{ranlib} program is another form of @sc{gnu} @code{ar}; running
@code{ranlib} is completely equivalent to executing @samp{ar -s}.
@xref{ar}.
@table @code
@item -v
@itemx -V
Show the version number of @code{ranlib}.
@end table
@node size
@chapter size
@kindex size
@cindex section sizes
@smallexample
size [ -A | -B | --format=@var{compatibility} ]
[ --help ] [ -d | -o | -x | --radix=@var{number} ]
[ --target=@var{bfdname} ] [ -V | --version ]
[ @var{objfile}@dots{} ]
@end smallexample
The @sc{gnu} @code{size} utility lists the section sizes---and the total
size---for each of the object or archive files @var{objfile} in its
argument list. By default, one line of output is generated for each
object file or each module in an archive.
@var{objfile}@dots{} are the object files to be examined.
If none are specified, the file @code{a.out} will be used.
The command line options have the following meanings:
@table @code
@item -A
@itemx -B
@itemx --format=@var{compatibility}
@cindex @code{size} display format
Using one of these options, you can choose whether the output from @sc{gnu}
@code{size} resembles output from System V @code{size} (using @samp{-A},
or @samp{--format=sysv}), or Berkeley @code{size} (using @samp{-B}, or
@samp{--format=berkeley}). The default is the one-line format similar to
Berkeley's.
@c Bonus for doc-source readers: you can also say --format=strange (or
@c anything else that starts with 's') for sysv, and --format=boring (or
@c anything else that starts with 'b') for Berkeley.
Here is an example of the Berkeley (default) format of output from
@code{size}:
@smallexample
size --format=Berkeley ranlib size
text data bss dec hex filename
294880 81920 11592 388392 5ed28 ranlib
294880 81920 11888 388688 5ee50 size
@end smallexample
@noindent
This is the same data, but displayed closer to System V conventions:
@smallexample
size --format=SysV ranlib size
ranlib :
section size addr
.text 294880 8192
.data 81920 303104
.bss 11592 385024
Total 388392
size :
section size addr
.text 294880 8192
.data 81920 303104
.bss 11888 385024
Total 388688
@end smallexample
@item --help
Show a summary of acceptable arguments and options.
@item -d
@itemx -o
@itemx -x
@itemx --radix=@var{number}
@cindex @code{size} number format
@cindex radix for section sizes
Using one of these options, you can control whether the size of each
section is given in decimal (@samp{-d}, or @samp{--radix=10}); octal
(@samp{-o}, or @samp{--radix=8}); or hexadecimal (@samp{-x}, or
@samp{--radix=16}). In @samp{--radix=@var{number}}, only the three
values (8, 10, 16) are supported. The total size is always given in two
radices; decimal and hexadecimal for @samp{-d} or @samp{-x} output, or
octal and hexadecimal if you're using @samp{-o}.
@item --target=@var{bfdname}
@cindex object code format
Specify that the object-code format for @var{objfile} is
@var{bfdname}. This option may not be necessary; @code{size} can
automatically recognize many formats.
@xref{Target Selection}, for more information.
@item -V
@itemx --version
Display the version number of @code{size}.
@end table
@node strings
@chapter strings
@kindex strings
@cindex listings strings
@cindex printing strings
@cindex strings, printing
@smallexample
strings [-afov] [-@var{min-len}] [-n @var{min-len}] [-t @var{radix}] [-]
[--all] [--print-file-name] [--bytes=@var{min-len}]
[--radix=@var{radix}] [--target=@var{bfdname}]
[--help] [--version] @var{file}@dots{}
@end smallexample
For each @var{file} given, @sc{gnu} @code{strings} prints the printable
character sequences that are at least 4 characters long (or the number
given with the options below) and are followed by an unprintable
character. By default, it only prints the strings from the initialized
and loaded sections of object files; for other types of files, it prints
the strings from the whole file.
@code{strings} is mainly useful for determining the contents of non-text
files.
@table @code
@item -a
@itemx --all
@itemx -
Do not scan only the initialized and loaded sections of object files;
scan the whole files.
@item -f
@itemx --print-file-name
Print the name of the file before each string.
@item --help
Print a summary of the program usage on the standard output and exit.
@item -@var{min-len}
@itemx -n @var{min-len}
@itemx --bytes=@var{min-len}
Print sequences of characters that are at least @var{min-len} characters
long, instead of the default 4.
@item -o
Like @samp{-t o}. Some other versions of @code{strings} have @samp{-o}
act like @samp{-t d} instead. Since we can not be compatible with both
ways, we simply chose one.
@item -t @var{radix}
@itemx --radix=@var{radix}
Print the offset within the file before each string. The single
character argument specifies the radix of the offset---@samp{o} for
octal, @samp{x} for hexadecimal, or @samp{d} for decimal.
@item --target=@var{bfdname}
@cindex object code format
Specify an object code format other than your system's default format.
@xref{Target Selection}, for more information.
@item -v
@itemx --version
Print the program version number on the standard output and exit.
@end table
@node strip
@chapter strip
@kindex strip
@cindex removing symbols
@cindex discarding symbols
@cindex symbols, discarding
@smallexample
strip [ -F @var{bfdname} | --target=@var{bfdname} ]
[ -I @var{bfdname} | --input-target=@var{bfdname} ]
[ -O @var{bfdname} | --output-target=@var{bfdname} ]
[ -s | --strip-all ] [ -S | -g | --strip-debug ]
[ -K @var{symbolname} | --keep-symbol=@var{symbolname} ]
[ -N @var{symbolname} | --strip-symbol=@var{symbolname} ]
[ -x | --discard-all ] [ -X | --discard-locals ]
[ -R @var{sectionname} | --remove-section=@var{sectionname} ]
[ -o @var{file} ] [ -p | --preserve-dates ]
[ -v | --verbose ] [ -V | --version ] [ --help ]
@var{objfile}@dots{}
@end smallexample
@sc{gnu} @code{strip} discards all symbols from object files
@var{objfile}. The list of object files may include archives.
At least one object file must be given.
@code{strip} modifies the files named in its argument,
rather than writing modified copies under different names.
@table @code
@item -F @var{bfdname}
@itemx --target=@var{bfdname}
Treat the original @var{objfile} as a file with the object
code format @var{bfdname}, and rewrite it in the same format.
@xref{Target Selection}, for more information.
@item --help
Show a summary of the options to @code{strip} and exit.
@item -I @var{bfdname}
@itemx --input-target=@var{bfdname}
Treat the original @var{objfile} as a file with the object
code format @var{bfdname}.
@xref{Target Selection}, for more information.
@item -O @var{bfdname}
@itemx --output-target=@var{bfdname}
Replace @var{objfile} with a file in the output format @var{bfdname}.
@xref{Target Selection}, for more information.
@item -R @var{sectionname}
@itemx --remove-section=@var{sectionname}
Remove any section named @var{sectionname} from the output file. This
option may be given more than once. Note that using this option
inappropriately may make the output file unusable.
@item -s
@itemx --strip-all
Remove all symbols.
@item -g
@itemx -S
@itemx --strip-debug
Remove debugging symbols only.
@item --strip-unneeded
Remove all symbols that are not needed for relocation processing.
@item -K @var{symbolname}
@itemx --keep-symbol=@var{symbolname}
Keep only symbol @var{symbolname} from the source file. This option may
be given more than once.
@item -N @var{symbolname}
@itemx --strip-symbol=@var{symbolname}
Remove symbol @var{symbolname} from the source file. This option may be
given more than once, and may be combined with strip options other than
@code{-K}.
@item -o @var{file}
Put the stripped output in @var{file}, rather than replacing the
existing file. When this argument is used, only one @var{objfile}
argument may be specified.
@item -p
@itemx --preserve-dates
Preserve the access and modification dates of the file.
@item -x
@itemx --discard-all
Remove non-global symbols.
@item -X
@itemx --discard-locals
Remove compiler-generated local symbols.
(These usually start with @samp{L} or @samp{.}.)
@item -V
@itemx --version
Show the version number for @code{strip}.
@item -v
@itemx --verbose
Verbose output: list all object files modified. In the case of
archives, @samp{strip -v} lists all members of the archive.
@end table
@node c++filt
@chapter c++filt
@kindex c++filt
@cindex demangling C++ symbols
@smallexample
c++filt [ -_ | --strip-underscores ]
[ -n | --no-strip-underscores ]
[ -s @var{format} | --format=@var{format} ]
[ --help ] [ --version ] [ @var{symbol}@dots{} ]
@end smallexample
The C++ language provides function overloading, which means that you can
write many functions with the same name (providing each takes parameters
of different types). All C++ function names are encoded into a
low-level assembly label (this process is known as
@dfn{mangling}). The @code{c++filt} program does the inverse mapping: it
decodes (@dfn{demangles}) low-level names into user-level names so that
the linker can keep these overloaded functions from clashing.
Every alphanumeric word (consisting of letters, digits, underscores,
dollars, or periods) seen in the input is a potential label. If the
label decodes into a C++ name, the C++ name replaces the low-level
name in the output.
You can use @code{c++filt} to decipher individual symbols:
@example
c++filt @var{symbol}
@end example
If no @var{symbol} arguments are given, @code{c++filt} reads symbol
names from the standard input and writes the demangled names to the
standard output. All results are printed on the standard output.
@table @code
@item -_
@itemx --strip-underscores
On some systems, both the C and C++ compilers put an underscore in front
of every name. For example, the C name @code{foo} gets the low-level
name @code{_foo}. This option removes the initial underscore. Whether
@code{c++filt} removes the underscore by default is target dependent.
@item -n
@itemx --no-strip-underscores
Do not remove the initial underscore.
@item -s @var{format}
@itemx --format=@var{format}
@sc{gnu} @code{nm} can decode three different methods of mangling, used by
different C++ compilers. The argument to this option selects which
method it uses:
@table @code
@item gnu
the one used by the @sc{gnu} compiler (the default method)
@item lucid
the one used by the Lucid compiler
@item arm
the one specified by the C++ Annotated Reference Manual
@end table
@item --help
Print a summary of the options to @code{c++filt} and exit.
@item --version
Print the version number of @code{c++filt} and exit.
@end table
@quotation
@emph{Warning:} @code{c++filt} is a new utility, and the details of its
user interface are subject to change in future releases. In particular,
a command-line option may be required in the the future to decode a name
passed as an argument on the command line; in other words,
@example
c++filt @var{symbol}
@end example
@noindent
may in a future release become
@example
c++filt @var{option} @var{symbol}
@end example
@end quotation
@node addr2line
@chapter addr2line
@kindex addr2line
@cindex address to file name and line number
@smallexample
addr2line [ -b @var{bfdname} | --target=@var{bfdname} ]
[ -C | --demangle ]
[ -e @var{filename} | --exe=@var{filename} ]
[ -f | --functions ] [ -s | --basename ]
[ -H | --help ] [ -V | --version ]
[ addr addr ... ]
@end smallexample
@code{addr2line} translates program addresses into file names and line
numbers. Given an address and an executable, it uses the debugging
information in the executable to figure out which file name and line
number are associated with a given address.
The executable to use is specified with the @code{-e} option. The
default is @file{a.out}.
@code{addr2line} has two modes of operation.
In the first, hexadecimal addresses are specified on the command line,
and @code{addr2line} displays the file name and line number for each
address.
In the second, @code{addr2line} reads hexadecimal addresses from
standard input, and prints the file name and line number for each
address on standard output. In this mode, @code{addr2line} may be used
in a pipe to convert dynamically chosen addresses.
The format of the output is @samp{FILENAME:LINENO}. The file name and
line number for each address is printed on a separate line. If the
@code{-f} option is used, then each @samp{FILENAME:LINENO} line is
preceded by a @samp{FUNCTIONNAME} line which is the name of the function
containing the address.
If the file name or function name can not be determined,
@code{addr2line} will print two question marks in their place. If the
line number can not be determined, @code{addr2line} will print 0.
The long and short forms of options, shown here as alternatives, are
equivalent.
@table @code
@item -b @var{bfdname}
@itemx --target=@var{bfdname}
@cindex object code format
Specify that the object-code format for the object files is
@var{bfdname}.
@item -C
@itemx --demangle
@cindex demangling in objdump
Decode (@dfn{demangle}) low-level symbol names into user-level names.
Besides removing any initial underscore prepended by the system, this
makes C++ function names readable. @xref{c++filt}, for more information
on demangling.
@item -e @var{filename}
@itemx --exe=@var{filename}
Specify the name of the executable for which addresses should be
translated. The default file is @file{a.out}.
@item -f
@itemx --functions
Display function names as well as file and line number information.
@item -s
@itemx --basenames
Display only the base of each file name.
@end table
@node nlmconv
@chapter nlmconv
@code{nlmconv} converts a relocatable object file into a NetWare
Loadable Module.
@ignore
@code{nlmconv} currently works with @samp{i386} object
files in @code{coff}, @sc{elf}, or @code{a.out} format, and @sc{SPARC}
object files in @sc{elf}, or @code{a.out} format@footnote{
@code{nlmconv} should work with any @samp{i386} or @sc{sparc} object
format in the Binary File Descriptor library. It has only been tested
with the above formats.}.
@end ignore
@quotation
@emph{Warning:} @code{nlmconv} is not always built as part of the binary
utilities, since it is only useful for NLM targets.
@end quotation
@smallexample
nlmconv [ -I @var{bfdname} | --input-target=@var{bfdname} ]
[ -O @var{bfdname} | --output-target=@var{bfdname} ]
[ -T @var{headerfile} | --header-file=@var{headerfile} ]
[ -d | --debug] [ -l @var{linker} | --linker=@var{linker} ]
[ -h | --help ] [ -V | --version ]
@var{infile} @var{outfile}
@end smallexample
@code{nlmconv} converts the relocatable @samp{i386} object file
@var{infile} into the NetWare Loadable Module @var{outfile}, optionally
reading @var{headerfile} for NLM header information. For instructions
on writing the NLM command file language used in header files, see the
@samp{linkers} section, @samp{NLMLINK} in particular, of the @cite{NLM
Development and Tools Overview}, which is part of the NLM Software
Developer's Kit (``NLM SDK''), available from Novell, Inc.
@code{nlmconv} uses the @sc{gnu} Binary File Descriptor library to read
@var{infile}; see @ref{BFD,,BFD,ld.info,Using LD}, for
more information.
@code{nlmconv} can perform a link step. In other words, you can list
more than one object file for input if you list them in the definitions
file (rather than simply specifying one input file on the command line).
In this case, @code{nlmconv} calls the linker for you.
@table @code
@item -I @var{bfdname}
@itemx --input-target=@var{bfdname}
Object format of the input file. @code{nlmconv} can usually determine
the format of a given file (so no default is necessary).
@xref{Target Selection}, for more information.
@item -O @var{bfdname}
@itemx --output-target=@var{bfdname}
Object format of the output file. @code{nlmconv} infers the output
format based on the input format, e.g. for a @samp{i386} input file the
output format is @samp{nlm32-i386}.
@xref{Target Selection}, for more information.
@item -T @var{headerfile}
@itemx --header-file=@var{headerfile}
Reads @var{headerfile} for NLM header information. For instructions on
writing the NLM command file language used in header files, see@ see the
@samp{linkers} section, of the @cite{NLM Development and Tools
Overview}, which is part of the NLM Software Developer's Kit, available
from Novell, Inc.
@item -d
@itemx --debug
Displays (on standard error) the linker command line used by @code{nlmconv}.
@item -l @var{linker}
@itemx --linker=@var{linker}
Use @var{linker} for any linking. @var{linker} can be an absolute or a
relative pathname.
@item -h
@itemx --help
Prints a usage summary.
@item -V
@itemx --version
Prints the version number for @code{nlmconv}.
@end table
@node windres
@chapter windres
@code{windres} may be used to manipulate Windows resources.
@quotation
@emph{Warning:} @code{windres} is not always built as part of the binary
utilities, since it is only useful for Windows targets.
@end quotation
@smallexample
windres [options] [input-file] [output-file]
@end smallexample
@code{windres} reads resources from an input file and copies them into
an output file. Either file may be in one of three formats:
@table @code
@item rc
A text format read by the Resource Compiler.
@item res
A binary format generated by the Resource Compiler.
@item coff
A COFF object or executable.
@end table
The exact description of these different formats is available in
documentation from Microsoft.
When @code{windres} converts from the @code{rc} format to the @code{res}
format, it is acting like the Windows Resource Compiler. When
@code{windres} converts from the @code{res} format to the @code{coff}
format, it is acting like the Windows @code{CVTRES} program.
When @code{windres} generates an @code{rc} file, the output is similar
but not identical to the format expected for the input. When an input
@code{rc} file refers to an external filename, an output @code{rc} file
will instead include the file contents.
If the input or output format is not specified, @code{windres} will
guess based on the file name, or, for the input file, the file contents.
A file with an extension of @file{.rc} will be treated as an @code{rc}
file, a file with an extension of @file{.res} will be treated as a
@code{res} file, and a file with an extension of @file{.o} or
@file{.exe} will be treated as a @code{coff} file.
If no output file is specified, @code{windres} will print the resources
in @code{rc} format to standard output.
The normal use is for you to write an @code{rc} file, use @code{windres}
to convert it to a COFF object file, and then link the COFF file into
your application. This will make the resources described in the
@code{rc} file available to Windows.
@table @code
@item -i @var{filename}
@itemx --input @var{filename}
The name of the input file. If this option is not used, then
@code{windres} will use the first non-option argument as the input file
name. If there are no non-option arguments, then @code{windres} will
read from standard input. @code{windres} can not read a COFF file from
standard input.
@item -o @var{filename}
@itemx --output @var{filename}
The name of the output file. If this option is not used, then
@code{windres} will use the first non-option argument, after any used
for the input file name, as the output file name. If there is no
non-option argument, then @code{windres} will write to standard output.
@code{windres} can not write a COFF file to standard output.
@item -I @var{format}
@itemx --input-format @var{format}
The input format to read. @var{format} may be @samp{res}, @samp{rc}, or
@samp{coff}. If no input format is specified, @code{windres} will
guess, as described above.
@item -O @var{format}
@itemx --output-format @var{format}
The output format to generate. @var{format} may be @samp{res},
@samp{rc}, or @samp{coff}. If no output format is specified,
@code{windres} will guess, as described above.
@item -F @var{target}
@itemx --target @var{target}
Specify the BFD format to use for a COFF file as input or output. This
is a BFD target name; you can use the @code{--help} option to see a list
of supported targets. Normally @code{windres} will use the default
format, which is the first one listed by the @code{--help} option.
@ref{Target Selection}.
@item --preprocessor @var{program}
When @code{windres} reads an @code{rc} file, it runs it through the C
preprocessor first. This option may be used to specify the preprocessor
to use, including any leading arguments. The default preprocessor
argument is @code{gcc -E -xc-header -DRC_INVOKED}.
@item --include-dir @var{directory}
Specify an include directory to use when reading an @code{rc} file.
@code{windres} will pass this to the preprocessor as an @code{-I}
option. @code{windres} will also search this directory when looking for
files named in the @code{rc} file.
@item --define @var{sym[=val]}
Specify a @code{-D} option to pass to the preprocessor when reading an
@code{rc} file.
@item --language @var{val}
Specify the default language to use when reading an @code{rc} file.
@var{val} should be a hexadecimal language code. The low eight bits are
the language, and the high eight bits are the sublanguage.
@item --help
Prints a usage summary.
@item --version
Prints the version number for @code{windres}.
@item --yydebug
If @code{windres} is compiled with @code{YYDEBUG} defined as @code{1},
this will turn on parser debugging.
@end table
@node dlltool
@chapter Create files needed to build and use DLLs
@cindex DLL
@kindex dlltool
@code{dlltool} may be used to create the files needed to build and use
dynamic link libraries (DLLs).
@quotation
@emph{Warning:} @code{dlltool} is not always built as part of the binary
utilities, since it is only useful for those targets which support DLLs.
@end quotation
@smallexample
dlltool [-d|--input-def @var{def-file-name}]
[-b|--base-file @var{base-file-name}]
[-e|--output-exp @var{exports-file-name}]
[-z|--output-def @var{def-file-name}]
[-l|--output-lib @var{library-file-name}]
[--export-all-symbols] [--no-export-all-symbols]
[--exclude-symbols @var{list}]
[--no-default-excludes]
[-S|--as @var{path-to-assembler}] [-f|--as-flags @var{options}]
[-D|--dllname @var{name}] [-m|--machine @var{machine}]
[-a|--add-indirect] [-U|--add-underscore] [-k|--kill-at]
[-A|--add-stdcall-alias]
[-x|--no-idata4] [-c|--no-idata5] [-i|--interwork]
[-n|--nodelete] [-v|--verbose] [-h|--help] [-V|--version]
[object-file @dots{}]
@end smallexample
@code{dlltool} reads its inputs, which can come from the @samp{-d} and
@samp{-b} options as well as object files specified on the command
line. It then processes these inputs and if the @samp{-e} option has
been specified it creates a exports file. If the @samp{-l} option
has been specified it creates a library file and if the @samp{-z} option
has been specified it creates a def file. Any or all of the -e, -l
and -z options can be present in one invocation of dlltool.
When creating a DLL, along with the source for the DLL, it is necessary
to have three other files. @code{dlltool} can help with the creation of
these files.
The first file is a @samp{.def} file which specifies which functions are
exported from the DLL, which functions the DLL imports, and so on. This
is a text file and can be created by hand, or @code{dlltool} can be used
to create it using the @samp{-z} option. In this case @code{dlltool}
will scan the object files specified on its command line looking for
those functions which have been specially marked as being exported and
put entries for them in the .def file it creates.
In order to mark a function as being exported from a DLL, it needs to
have an @samp{-export:<name_of_function>} entry in the @samp{.drectve}
section of the object file. This can be done in C by using the
asm() operator:
@smallexample
asm (".section .drectve");
asm (".ascii \"-export:my_func\"");
int my_func (void) @{ @dots{} @}
@end smallexample
The second file needed for DLL creation is an exports file. This file
is linked with the object files that make up the body of the DLL and it
handles the interface between the DLL and the outside world. This is a
binary file and it can be created by giving the @samp{-e} option to
@code{dlltool} when it is creating or reading in a .def file.
The third file needed for DLL creation is the library file that programs
will link with in order to access the functions in the DLL. This file
can be created by giving the @samp{-l} option to dlltool when it
is creating or reading in a .def file.
@code{dlltool} builds the library file by hand, but it builds the
exports file by creating temporary files containing assembler statements
and then assembling these. The @samp{-S} command line option can be
used to specify the path to the assembler that dlltool will use,
and the @samp{-f} option can be used to pass specific flags to that
assembler. The @samp{-n} can be used to prevent dlltool from deleting
these temporary assembler files when it is done, and if @samp{-n} is
specified twice then this will prevent dlltool from deleting the
temporary object files it used to build the library.
Here is an example of creating a DLL from a source file @samp{dll.c} and
also creating a program (from an object file called @samp{program.o})
that uses that DLL:
@smallexample
gcc -c dll.c
dlltool -e exports.o -l dll.lib dll.o
gcc dll.o exports.o -o dll.dll
gcc program.o dll.lib -o program
@end smallexample
The command line options have the following meanings:
@table @code
@item -d @var{filename}
@itemx --input-def @var{filename}
@cindex input .def file
Specifies the name of a .def file to be read in and processed.
@item -b @var{filename}
@itemx --base-file @var{filename}
@cindex base files
Specifies the name of a base file to be read in and processed. The
contents of this file will be added to the relocation section in the
exports file generated by dlltool.
@item -e @var{filename}
@itemx --output-exp @var{filename}
Specifies the name of the export file to be created by dlltool.
@item -z @var{filename}
@itemx --output-def @var{filename}
Specifies the name of the .def file to be created by dlltool.
@item -l @var{filename}
@itemx --output-lib @var{filename}
Specifies the name of the library file to be created by dlltool.
@item --export-all-symbols
Treat all global and weak defined symbols found in the input object
files as symbols to be exported. There is a small list of symbols which
are not exported by default; see the @code{--no-default-excludes}
option. You may add to the list of symbols to not export by using the
@code{--exclude-symbols} option.
@item --no-export-all-symbols
Only export symbols explicitly listed in an input .def file or in
@samp{.drectve} sections in the input object files. This is the default
behaviour. The @samp{.drectve} sections are created by @samp{dllexport}
attributes in the source code.
@item --exclude-symbols @var{list}
Do not export the symbols in @var{list}. This is a list of symbol names
separated by comma or colon characters. The symbol names should not
contain a leading underscore. This is only meaningful when
@code{--export-all-symbols} is used.
@item --no-default-excludes
When @code{--export-all-symbols} is used, it will by default avoid
exporting certain special symbols. The current list of symbols to avoid
exporting is @samp{DllMain@@12}, @samp{DllEntryPoint@@0},
@samp{impure_ptr}. You may use the @code{--no-default-excludes} option
to go ahead and export these special symbols. This is only meaningful
when @code{--export-all-symbols} is used.
@item -S @var{path}
@itemx --as @var{path}
Specifies the path, including the filename, of the assembler to be used
to create the exports file.
@item -f @var{switches}
@itemx --as-flags @var{switches}
Specifies any specific command line switches to be passed to the
assembler when building the exports file. This option will work even if
the @samp{-S} option is not used. This option only takes one argument,
and if it occurs more than once on the command line, then later
occurrences will override earlier occurrences. So if it is necessary to
pass multiple switches to the assembler they should be enclosed in
double quotes.
@item -D @var{name}
@itemx --dll-name @var{name}
Specifies the name to be stored in the .def file as the name of the DLL
when the @samp{-e} option is used. If this option is not present, then
the filename given to the @samp{-e} option will be used as the name of
the DLL.
@item -m @var{machine}
@itemx -machine @var{machine}
Specifies the type of machine for which the library file should be
built. @code{dlltool} has a built in default type, depending upon how
it was created, but this option can be used to override that. This is
normally only useful when creating DLLs for an ARM processor, when the
contents of the DLL are actually encode using THUMB instructions.
@item -a
@itemx --add-indirect
Specifies that when @code{dlltool} is creating the exports file it
should add a section which allows the exported functions to be
referenced without using the import library. Whatever the hell that
means!
@item -U
@itemx --add-underscore
Specifies that when @code{dlltool} is creating the exports file it
should prepend an underscore to the names of the exported functions.
@item -k
@itemx --kill-at
Specifies that when @code{dlltool} is creating the exports file it
should not append the string @samp{@@ <number>}. These numbers are
called ordinal numbers and they represent another way of accessing the
function in a DLL, other than by name.
@item -A
@itemx --add-stdcall-alias
Specifies that when @code{dlltool} is creating the exports file it
should add aliases for stdcall symbols without @samp{@@ <number>}
in addition to the symbols with @samp{@@ <number>}.
@item -x
@itemx --no-idata4
Specifies that when @code{dlltool} is creating the exports and library
files it should omit the .idata4 section. This is for compatibility
with certain operating systems.
@item -c
@itemx --no-idata5
Specifies that when @code{dlltool} is creating the exports and library
files it should omit the .idata5 section. This is for compatibility
with certain operating systems.
@item -i
@itemx --interwork
Specifies that @code{dlltool} should mark the objects in the library
file and exports file that it produces as supporting interworking
between ARM and THUMB code.
@item -n
@itemx --nodelete
Makes @code{dlltool} preserve the temporary assembler files it used to
create the exports file. If this option is repeated then dlltool will
also preserve the temporary object files it uses to create the library
file.
@item -v
@itemx --verbose
Make dlltool describe what it is doing.
@item -h
@itemx --help
Displays a list of command line options and then exits.
@item -V
@itemx --version
Displays dlltool's version number and then exits.
@end table
@node readelf
@chapter readelf
@cindex ELF file information
@kindex readelf
@smallexample
readelf [ -a | --all ]
[ -h | --file-header]
[ -l | --program-headers | --segments]
[ -S | --section-headers | --sections]
[ -s | --symbols]
[ -r | --relocs]
[ -d | --dynamic]
[ -V | --version-info]
[ -D | --use-dynamic]
[ -x <number> | --hex-dump=<number>]
[ -v | --version]
[ -H | --help]
@var{elffile}@dots{}
@end smallexample
@code{readelf} displays information about one or more ELF format object
files. The options control what particular information to display.
@var{elffile}@dots{} are the object files to be examined. At the
moment, @code{readelf} does not support examining archives, nor does it
support examing 64 bit ELF files.
The long and short forms of options, shown here as alternatives, are
equivalent. At least one option besides @samp{-v} or @samp{-H} must be
given.
@table @code
@item -a
@itemx --all
Equivalent to specifiying @samp{--file-header},
@samp{--program-headers}, @samp{--sections}, @samp{--symbols},
@samp{--relocs}, @samp{--dynamic} and @samp{--version-info}.
@item -h
@itemx --file-header
@cindex ELF file header information
Displays the information contained in the ELF header at the start of the
file.
@item -l
@itemx --program-headers
@itemx --segments
@cindex ELF program header information
@cindex ELF segment information
Displays the information contained in the file's segment headers, if it
has any.
@item -S
@itemx --sections
@cindex ELF section information
Displays the information contained in the file's section headers, if it
has any.
@item -s
@itemx --symbols
@cindex ELF symbol table information
Displays the entries in symbol table section of the file, if it has one.
@item -r
@itemx --relocs
@cindex ELF reloc information
Displays the contents of the file's relocation section, if it ha one.
@item -d
@itemx --dynamic
@cindex ELF dynamic section information
Displays the contents of the file's dynamic section, if it has one.
@item -V
@itemx --version-info
@cindex ELF version sections informations
Displays the contents of the version sections in the file, it they
exist.
@item -D
@itemx --use-dynamic
When displaying symbols, this option makes @code{readelf} use the
symblol table in the file's dynamic section, rather than the one in the
symbols section.
@item -x <number>
@itemx --hex-dump=<number>
Displays the contents of the indicated section as a hexadecimal dump.
@item -v
@itemx --version
Display the version number of readelf.
@item -H
@itemx --help
Display the command line options understood by @code{readelf}.
@end table
@node Selecting The Target System
@chapter Selecting the target system
You can specify three aspects of the target system to the @sc{gnu}
binary file utilities, each in several ways:
@itemize @bullet
@item
the target
@item
the architecture
@item
the linker emulation (which applies to the linker only)
@end itemize
In the following summaries, the lists of ways to specify values are in
order of decreasing precedence. The ways listed first override those
listed later.
The commands to list valid values only list the values for which the
programs you are running were configured. If they were configured with
@samp{--enable-targets=all}, the commands list most of the available
values, but a few are left out; not all targets can be configured in at
once because some of them can only be configured @dfn{native} (on hosts
with the same type as the target system).
@menu
* Target Selection::
* Architecture Selection::
* Linker Emulation Selection::
@end menu
@node Target Selection
@section Target Selection
A @dfn{target} is an object file format. A given target may be
supported for multiple architectures (@pxref{Architecture Selection}).
A target selection may also have variations for different operating
systems or architectures.
The command to list valid target values is @samp{objdump -i}
(the first column of output contains the relevant information).
Some sample values are: @samp{a.out-hp300bsd}, @samp{ecoff-littlemips},
@samp{a.out-sunos-big}.
You can also specify a target using a configuration triplet. This is
the same sort of name that is passed to configure to specify a target.
When you use a configuration triplet as an argument, it must be fully
canonicalized. You can see the canonical version of a triplet by
running the shell script @file{config.sub} which is included with the
sources.
Some sample configuration triplets are: @samp{m68k-hp-bsd},
@samp{mips-dec-ultrix}, @samp{sparc-sun-sunos}.
@subheading @code{objdump} Target
Ways to specify:
@enumerate
@item
command line option: @samp{-b} or @samp{--target}
@item
environment variable @code{GNUTARGET}
@item
deduced from the input file
@end enumerate
@subheading @code{objcopy} and @code{strip} Input Target
Ways to specify:
@enumerate
@item
command line options: @samp{-I} or @samp{--input-target}, or @samp{-F} or @samp{--target}
@item
environment variable @code{GNUTARGET}
@item
deduced from the input file
@end enumerate
@subheading @code{objcopy} and @code{strip} Output Target
Ways to specify:
@enumerate
@item
command line options: @samp{-O} or @samp{--output-target}, or @samp{-F} or @samp{--target}
@item
the input target (see ``@code{objcopy} and @code{strip} Input Target'' above)
@item
environment variable @code{GNUTARGET}
@item
deduced from the input file
@end enumerate
@subheading @code{nm}, @code{size}, and @code{strings} Target
Ways to specify:
@enumerate
@item
command line option: @samp{--target}
@item
environment variable @code{GNUTARGET}
@item
deduced from the input file
@end enumerate
@subheading Linker Input Target
Ways to specify:
@enumerate
@item
command line option: @samp{-b} or @samp{--format}
(@pxref{Options,,Options,ld.info,Using LD})
@item
script command @code{TARGET}
(@pxref{Option Commands,,Option Commands,ld.info,Using LD})
@item
environment variable @code{GNUTARGET}
(@pxref{Environment,,Environment,ld.info,Using LD})
@item
the default target of the selected linker emulation
(@pxref{Linker Emulation Selection})
@end enumerate
@subheading Linker Output Target
Ways to specify:
@enumerate
@item
command line option: @samp{-oformat}
(@pxref{Options,,Options,ld.info,Using LD})
@item
script command @code{OUTPUT_FORMAT}
(@pxref{Option Commands,,Option Commands,ld.info,Using LD})
@item
the linker input target (see ``Linker Input Target'' above)
@end enumerate
@node Architecture Selection
@section Architecture selection
An @dfn{architecture} is a type of @sc{cpu} on which an object file is
to run. Its name may contain a colon, separating the name of the
processor family from the name of the particular @sc{cpu}.
The command to list valid architecture values is @samp{objdump -i} (the
second column contains the relevant information).
Sample values: @samp{m68k:68020}, @samp{mips:3000}, @samp{sparc}.
@subheading @code{objdump} Architecture
Ways to specify:
@enumerate
@item
command line option: @samp{-m} or @samp{--architecture}
@item
deduced from the input file
@end enumerate
@subheading @code{objcopy}, @code{nm}, @code{size}, @code{strings} Architecture
Ways to specify:
@enumerate
@item
deduced from the input file
@end enumerate
@subheading Linker Input Architecture
Ways to specify:
@enumerate
@item
deduced from the input file
@end enumerate
@subheading Linker Output Architecture
Ways to specify:
@enumerate
@item
script command @code{OUTPUT_ARCH}
(@pxref{Option Commands,,Option Commands,ld.info,Using LD})
@item
the default architecture from the linker output target
(@pxref{Target Selection})
@end enumerate
@node Linker Emulation Selection
@section Linker emulation selection
A linker @dfn{emulation} is a ``personality'' of the linker, which gives
the linker default values for the other aspects of the target system.
In particular, it consists of
@itemize @bullet
@item
the linker script
@item
the target
@item
several ``hook'' functions that are run at certain stages of the linking
process to do special things that some targets require
@end itemize
The command to list valid linker emulation values is @samp{ld -V}.
Sample values: @samp{hp300bsd}, @samp{mipslit}, @samp{sun4}.
Ways to specify:
@enumerate
@item
command line option: @samp{-m}
(@pxref{Options,,Options,ld.info,Using LD})
@item
environment variable @code{LDEMULATION}
@item
compiled-in @code{DEFAULT_EMULATION} from @file{Makefile},
which comes from @code{EMUL} in @file{config/@var{target}.mt}
@end enumerate
@node Reporting Bugs
@chapter Reporting Bugs
@cindex bugs
@cindex reporting bugs
Your bug reports play an essential role in making the binary utilities
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 the binary
utilities work better. Bug reports are your contribution to their
maintenance.
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 crash
@item
If a binary utility gets a fatal signal, for any input whatever, that is
a bug. Reliable utilities never crash.
@cindex error on valid input
@item
If a binary utility produces an error message for valid input, that is a
bug.
@item
If you are an experienced user of binary utilities, your suggestions for
improvement are welcome in any case.
@end itemize
@node Bug Reporting
@section How to report bugs
@cindex bug reports
@cindex bugs, reporting
A number of companies and individuals offer support for @sc{gnu}
products. If you obtained the binary utilities 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.
In any event, we also recommend that you send bug reports for the binary
utilities to @samp{bug-gnu-utils@@gnu.org}.
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 a file 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 pathname is stored in memory; perhaps, if the pathname were
different, the contents of that location would fool the utility 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 if
it is new to us. Therefore, always write your bug reports on the assumption
that the bug has not been reported previously.
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 the utility. Each utility announces it if you start it
with the @samp{--version} argument.
Without this, we will not know whether there is any point in looking for
the bug in the current version of the binary utilities.
@item
Any patches you may have applied to the source, including any patches
made to the @code{BFD} library.
@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 the utilities---e.g.
``@code{gcc-2.7}''.
@item
The command arguments you gave the utility to observe the bug. 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 file, or set of input files, that will reproduce the
bug. If the utility is reading an object file or files, then it is
generally most helpful to send the actual object files, uuencoded if
necessary to get them through the mail system. Making them available
for anonymous FTP is not as good, but may be the only reasonable choice
for large object files.
If the source files were produced exclusively using @sc{gnu} programs
(e.g., @code{gcc}, @code{gas}, and/or the @sc{gnu} @code{ld}), then it
may be OK to send the source files rather than the object files. In
this case, be sure to say exactly what version of @code{gcc}, or
whatever, was used to produce the object files. Also say how
@code{gcc}, or whatever, was configured.
@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 the utility 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 the utility 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.
@item
If you wish to suggest changes to the source, send us context diffs, as
generated by @code{diff} with the @samp{-u}, @samp{-c}, or @samp{-p}
option. Always send diffs from the old file to the new file. If you
even discuss something in the @code{ld} 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 programs as complicated as the binary utilities 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
@node Index
@unnumbered Index
@printindex cp
@contents
@bye
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