mirror of
https://sourceware.org/git/binutils-gdb.git
synced 2024-12-09 04:21:49 +08:00
99fabbc973
The SHF_GNU_RETAIN section flag is an extension to the GNU ELF OSABI. It is defined as follows: ========================================================= Section Attribute Flags +-------------------------------------+ | Name | Value | +-------------------------------------+ | SHF_GNU_RETAIN | 0x200000 (1 << 21) | +-------------------------------------+ SHF_GNU_RETAIN The link editor should not garbage collect the section. ========================================================= The .section directive accepts the "R" flag, which indicates SHF_GNU_RETAIN should be applied to the section. There is not a direct mapping of SHF_GNU_RETAIN to the BFD section flag SEC_KEEP. Keeping these flags distinct allows SHF_GNU_RETAIN sections to be explicitly removed by placing them in /DISCARD/. bfd/ChangeLog: * elf-bfd.h (enum elf_gnu_osabi): Add elf_gnu_osabi_retain. (struct elf_obj_tdata): Increase has_gnu_osabi to 4 bits. * elf.c (_bfd_elf_make_section_from_shdr): Set elf_gnu_osabi_retain for SHF_GNU_RETAIN. (_bfd_elf_final_write_processing): Report if SHF_GNU_RETAIN is not supported by the OSABI. Adjust error messages. * elflink.c (elf_link_input_bfd): Copy enabled has_gnu_osabi bits from input BFD to output BFD. (bfd_elf_gc_sections): gc_mark the section if SHF_GNU_RETAIN is set. binutils/ChangeLog: * NEWS: Announce SHF_GNU_RETAIN support. * readelf.c (get_elf_section_flags): Handle SHF_GNU_RETAIN. Recognize SHF_GNU_RETAIN and SHF_GNU_MBIND only for supported OSABIs. * testsuite/binutils-all/readelf.exp: Run new tests. Don't run run_dump_test when there isn't an assembler available. * testsuite/lib/binutils-common.exp (supports_gnu_osabi): Adjust comment. * testsuite/binutils-all/readelf-maskos-1a.d: New test. * testsuite/binutils-all/readelf-maskos-1b.d: New test. * testsuite/binutils-all/readelf-maskos.s: New test. * testsuite/binutils-all/retain1.s: New test. * testsuite/binutils-all/retain1a.d: New test. * testsuite/binutils-all/retain1b.d: New test. gas/ChangeLog: * NEWS: Announce SHF_GNU_RETAIN support. * config/obj-elf.c (obj_elf_change_section): Merge SHF_GNU_RETAIN bit between section declarations. (obj_elf_parse_section_letters): Handle 'R' flag. Handle numeric flag values within the SHF_MASKOS range. (obj_elf_section): Validate SHF_GNU_RETAIN usage. * doc/as.texi: Document 'R' flag to .section directive. * testsuite/gas/elf/elf.exp: Run new tests. * testsuite/gas/elf/section10.d: Unset SHF_GNU_RETAIN bit. * testsuite/gas/elf/section10.s: Likewise. * testsuite/gas/elf/section22.d: New test. * testsuite/gas/elf/section22.s: New test. * testsuite/gas/elf/section23.s: New test. * testsuite/gas/elf/section23a.d: New test. * testsuite/gas/elf/section23b.d: New test. * testsuite/gas/elf/section23b.err: New test. * testsuite/gas/elf/section24.l: New test. * testsuite/gas/elf/section24.s: New test. * testsuite/gas/elf/section24a.d: New test. * testsuite/gas/elf/section24b.d: New test. include/ChangeLog: * elf/common.h (SHF_GNU_RETAIN): Define. ld/ChangeLog: * NEWS: Announce support for SHF_GNU_RETAIN. * ld.texi (garbage collection): Document SHF_GNU_RETAIN. (Output Section Discarding): Likewise. * testsuite/ld-elf/elf.exp: Run new tests. * testsuite/ld-elf/retain1.s: New test. * testsuite/ld-elf/retain1a.d: New test. * testsuite/ld-elf/retain1b.d: New test. * testsuite/ld-elf/retain2.d: New test. * testsuite/ld-elf/retain2.ld: New test. * testsuite/ld-elf/retain2.map: New test. * testsuite/ld-elf/retain3.d: New test. * testsuite/ld-elf/retain3.s: New test. * testsuite/ld-elf/retain4.d: New test. * testsuite/ld-elf/retain4.s: New test. * testsuite/ld-elf/retain5.d: New test. * testsuite/ld-elf/retain5.map: New test. * testsuite/ld-elf/retain5lib.s: New test. * testsuite/ld-elf/retain5main.s: New test. * testsuite/ld-elf/retain6a.d: New test. * testsuite/ld-elf/retain6b.d: New test. * testsuite/ld-elf/retain6lib.s: New test. * testsuite/ld-elf/retain6main.s: New test. |
||
---|---|---|
.. | ||
emulparams | ||
emultempl | ||
po | ||
scripttempl | ||
testsuite | ||
.gitignore | ||
aclocal.m4 | ||
ChangeLog | ||
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-2018 | ||
ChangeLog-2019 | ||
ChangeLog-9197 | ||
ChangeLog-9899 | ||
config.in | ||
configure | ||
configure.ac | ||
configure.host | ||
configure.tgt | ||
deffile.h | ||
deffilep.y | ||
dep-in.sed | ||
elf-hints-local.h | ||
fdl.texi | ||
gen-doc.texi | ||
genscrba.sh | ||
genscripts.sh | ||
h8-doc.texi | ||
ld.h | ||
ld.texi | ||
ldbuildid.c | ||
ldbuildid.h | ||
ldcref.c | ||
ldctor.c | ||
ldctor.h | ||
ldelf.c | ||
ldelf.h | ||
ldelfgen.c | ||
ldelfgen.h | ||
ldemul.c | ||
ldemul.h | ||
ldexp.c | ||
ldexp.h | ||
ldfile.c | ||
ldfile.h | ||
ldgram.y | ||
ldint.texi | ||
ldlang.c | ||
ldlang.h | ||
ldlex-wrapper.c | ||
ldlex.h | ||
ldlex.l | ||
ldmain.c | ||
ldmain.h | ||
ldmisc.c | ||
ldmisc.h | ||
ldver.c | ||
ldver.h | ||
ldwrite.c | ||
ldwrite.h | ||
lexsup.c | ||
MAINTAINERS | ||
Makefile.am | ||
Makefile.in | ||
mri.c | ||
mri.h | ||
NEWS | ||
pe-dll.c | ||
pe-dll.h | ||
pep-dll.c | ||
pep-dll.h | ||
plugin.c | ||
plugin.h | ||
README | ||
stamp-h.in | ||
sysdep.h | ||
testplug2.c | ||
testplug3.c | ||
testplug4.c | ||
testplug.c | ||
TODO |
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.texi), as well as the
beginnings of an internals manual (ldint.texi).
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.texi 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) 2012-2020 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.