binutils-gdb/ld
Nick Clifton 97a232d733 Add -z undefs option to the ELF linker.
Currently we have no obvious way to revert the action of the "-z defs"
  command line option.  The "--unresolved-symbols=ignore-in-object-files"
  does pretty much what is needed, but it is non-obvious and it also
  touches the setting for reporting unresolved symbol references from
  shared libraries.  So I am proposing adding a "-z undefs" option to be
  the inverse of "-z defs".  (I thought that "-z nodefs" might be
  confusing since it implies banning all definitions, rather than
  allowing them).

  In addition the description of the "-z defs" option in the linker
  documentation is misleading in one place, where it says:

    'defs'
       Disallows undefined symbols in object files.  Undefined
       symbols in shared libraries are still allowed.

  whereas later on it gets it right:

    '-z defs'
       Report unresolved symbol references from regular object files.
       This is done even if the linker is creating a non-symbolic shared
       library.  The switch '--[no-]allow-shlib-undefined' controls the
       behaviour for reporting unresolved references found in shared
       libraries being linked in.

	* emultempl/elf32.em (_handle_option): Add support for "-z undefs"
	as the opposite of "-z defs".
	* ld.texinfo: Document the new option.  Update the description of
	the -z defs option to make it clear that it does generate an error
	if an undefined symbol reference is found in an object file whilst
	creating a shared library.
	* NEWS: Document this new feature.
2018-01-12 08:15:55 +00:00
..
emulparams RISC-V: Disable shared library support for embedded elf. 2018-01-05 14:29:49 -08:00
emultempl Add -z undefs option to the ELF linker. 2018-01-12 08:15:55 +00:00
po Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
scripttempl ld: Add "-z separate-code" option to ELF linker 2018-01-11 19:01:52 -08:00
testsuite ld: Replace "-z textonly" with "-z separate-code" 2018-01-11 20:46:01 -08:00
.gitignore
aclocal.m4
ChangeLog Add -z undefs option to the ELF linker. 2018-01-12 08:15:55 +00:00
ChangeLog-0001
ChangeLog-0203
ChangeLog-2004
ChangeLog-2005
ChangeLog-2006
ChangeLog-2007
ChangeLog-2008
ChangeLog-2009
ChangeLog-2010
ChangeLog-2011
ChangeLog-2012
ChangeLog-2013
ChangeLog-2014
ChangeLog-2015
ChangeLog-2016
ChangeLog-2017 ChangeLog rotation 2018-01-03 17:49:42 +10:30
ChangeLog-9197
ChangeLog-9899
config.in
configure ld whitespace fixes 2017-10-12 23:30:43 +10:30
configure.ac Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
configure.host Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
configure.tgt Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
deffile.h Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
deffilep.y Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
dep-in.sed
elf-hints-local.h
fdl.texi
gen-doc.texi Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
genscrba.sh
genscripts.sh ld: Add "-z separate-code" option to ELF linker 2018-01-11 19:01:52 -08:00
h8-doc.texi Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
ld.h Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
ld.texinfo Add -z undefs option to the ELF linker. 2018-01-12 08:15:55 +00:00
ldbuildid.c Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
ldbuildid.h Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
ldcref.c Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
ldctor.c Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
ldctor.h Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
ldemul.c Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
ldemul.h Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
ldexp.c ld: Remove unused expression state 2018-01-11 17:35:35 +00:00
ldexp.h ld: Remove unused expression state 2018-01-11 17:35:35 +00:00
ldfile.c Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
ldfile.h Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
ldgram.y Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
ldint.texinfo Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
ldlang.c ld: Fix issue where PROVIDE overrides defined symbol 2018-01-11 17:35:35 +00:00
ldlang.h Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
ldlex-wrapper.c Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
ldlex.h Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
ldlex.l Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
ldmain.c Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
ldmain.h Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
ldmisc.c Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
ldmisc.h Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
ldver.c Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
ldver.h Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
ldwrite.c Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
ldwrite.h Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
lexsup.c ld: Add "-z separate-code" option to ELF linker 2018-01-11 19:01:52 -08:00
MAINTAINERS Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
Makefile.am Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
Makefile.in Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
mri.c Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
mri.h Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
NEWS Add -z undefs option to the ELF linker. 2018-01-12 08:15:55 +00:00
pe-dll.c Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
pe-dll.h Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
pep-dll.c Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
pep-dll.h Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
plugin.c Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
plugin.h Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
README Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
stamp-h.in
sysdep.h Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
testplug2.c Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
testplug3.c Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
testplug4.c Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
testplug.c Update year range in copyright notice of binutils files 2018-01-03 17:49:56 +10:30
TODO

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		README for LD

This is the GNU linker.  It is distributed with other "binary
utilities" which should be in ../binutils.  See ../binutils/README for
more general notes, including where to send bug reports.

There are many features of the linker:

* The linker uses a Binary File Descriptor library (../bfd)
  that it uses to read and write object files.  This helps
  insulate the linker itself from the format of object files.

* The linker supports a number of different object file
  formats.  It can even handle multiple formats at once:
  Read two input formats and write a third.

* The linker can be configured for cross-linking.

* The linker supports a control language.

* There is a user manual (ld.texinfo), as well as the
  beginnings of an internals manual (ldint.texinfo).

Installation
============

See ../binutils/README.

If you want to make a cross-linker, you may want to specify
a different search path of -lfoo libraries than the default.
You can do this by setting the LIB_PATH variable in ./Makefile
or using the --with-lib-path configure switch.

To build just the linker, make the target all-ld from the top level
directory (one directory above this one).

Porting to a new target
=======================

See the ldint.texinfo manual.

Reporting bugs etc
===========================

See ../binutils/README.

Known problems
==============

The Solaris linker normally exports all dynamic symbols from an
executable.  The GNU linker does not do this by default.  This is
because the GNU linker tries to present the same interface for all
similar targets (in this case, all native ELF targets).  This does not
matter for normal programs, but it can make a difference for programs
which try to dlopen an executable, such as PERL or Tcl.  You can make
the GNU linker export all dynamic symbols with the -E or
--export-dynamic command line option.

HP/UX 9.01 has a shell bug that causes the linker scripts to be
generated incorrectly.  The symptom of this appears to be "fatal error
- scanner input buffer overflow" error messages.  There are various
workarounds to this:
  * Build and install bash, and build with "make SHELL=bash".
  * Update to a version of HP/UX with a working shell (e.g., 9.05).
  * Replace "(. ${srcdir}/scripttempl/${SCRIPT_NAME}.sc)" in
    genscripts.sh with "sh ${srcdir}..." (no parens) and make sure the
    emulparams script used exports any shell variables it sets.

Copyright (C) 2012-2018 Free Software Foundation, Inc.

Copying and distribution of this file, with or without modification,
are permitted in any medium without royalty provided the copyright
notice and this notice are preserved.