@set POWERPC
@set POWERPC64
@set Renesas
+@set S/390
@set SPU
@set TICOFF
@set WIN32
@ifset POWERPC64
* PowerPC64 ELF64:: ld and PowerPC64 64-bit ELF Support
@end ifset
+@ifset S/390
+* S/390 ELF:: ld and S/390 ELF Support
+@end ifset
@ifset SPU
* SPU ELF:: ld and SPU ELF Support
@end ifset
how @command{ld} searches for a linker script unless @option{-T}
option is specified.
-If @var{searchdir} begins with @code{=}, then the @code{=} will be replaced
-by the @dfn{sysroot prefix}, controlled by the @samp{--sysroot} option, or
-specified when the linker is configured.
+If @var{searchdir} begins with @code{=} or @code{$SYSROOT}, then this
+prefix will be replaced by the @dfn{sysroot prefix}, controlled by the
+@samp{--sysroot} option, or specified when the linker is configured.
@ifset UsesEnvVars
The default set of paths searched (without being specified with
@item place
Orphan sections are placed into a suitable output section following
the strategy described in @ref{Orphan Sections}. The option
-@samp{--unique} also effects how sections are placed.
+@samp{--unique} also affects how sections are placed.
@item discard
All orphan sections are discarded, by placing them in the
module aren't visible to the resulting shared library. Supported for
i386 and x86-64.
+@item dynamic-undefined-weak
+Make undefined weak symbols dynamic when building a dynamic object,
+if they are referenced from a regular object file and not forced local
+by symbol visibility or versioning. Not all targets support this
+option.
+
@item nodynamic-undefined-weak
-Don't treat undefined weak symbols as dynamic when building executable.
-This option overrides linker backend default. It can be used to avoid
-dynamic relocations against undefined weak symbols in executable.
-Supported for i386 and x86-64.
+Do not make undefined weak symbols dynamic when building a dynamic
+object. Not all targets support this option. If neither
+@option{-z nodynamic-undefined-weak} nor @option{-z dynamic-undefined-weak}
+are given, a target may default to either option being in force, or
+make some other selection of undefined weak symbols dynamic.
@item noreloc-overflow
Disable relocation overflow check. This can be used to disable
overflow at run-time. Supported for x86_64.
@item call-nop=prefix-addr
-@itemx call-nop=prefix-nop
@itemx call-nop=suffix-nop
@itemx call-nop=prefix-@var{byte}
@itemx call-nop=suffix-@var{byte}
Specify the 1-byte @code{NOP} padding when transforming indirect call
to a locally defined function, foo, via its GOT slot.
@option{call-nop=prefix-addr} generates @code{0x67 call foo}.
-@option{call-nop=prefix-nop} generates @code{0x90 call foo}.
@option{call-nop=suffix-nop} generates @code{call foo 0x90}.
@option{call-nop=prefix-@var{byte}} generates @code{@var{byte} call foo}.
@option{call-nop=suffix-@var{byte}} generates @code{call foo @var{byte}}.
Supported for i386 and x86_64.
+@item ibtplt
+Generate Intel Indirect Branch Tracking (IBT) enabled PLT entries.
+Supported for Linux/i386 and Linux/x86_64.
+
+@item IBT
+Generate GNU_PROPERTY_X86_FEATURE_1_IBT in .note.gnu.property section
+to indicate compatibility with IBT. This also implies @option{ibtplt}.
+Supported for Linux/i386 and Linux/x86_64.
+
+@item shstk
+Generate GNU_PROPERTY_X86_FEATURE_1_SHSTK in .note.gnu.property section
+to indicate compatibility with Intel Shadow Stack. Supported for
+Linux/i386 and Linux/x86_64.
+
@end table
Other keywords are ignored for Solaris compatibility.
duplicate when there are many dynamic modules with specialized search
paths for runtime symbol resolution.
+@cindex group allocation in linker script
+@cindex section groups
+@cindex COMDAT
+@kindex --force-group-allocation
+@item --force-group-allocation
+This option causes the linker to place section group members like
+normal input sections, and to delete the section groups. This is the
+default behaviour for a final link but this option can be used to
+change the behaviour of a relocatable link (@samp{-r}). The script
+command @code{FORCE_GROUP_ALLOCATION} has the same
+effect. @xref{Miscellaneous Commands}.
+
@cindex symbols, from command line
@kindex --defsym=@var{symbol}=@var{exp}
@item --defsym=@var{symbol}=@var{expression}
open the file in the current directory. If it is not found, the
linker will search through the archive library search path.
The @dfn{sysroot prefix} can also be forced by specifying @code{=}
-as the first character in the filename path. See also the
-description of @samp{-L} in @ref{Options,,Command Line Options}.
+as the first character in the filename path, or prefixing the filename
+path with @code{$SYSROOT}. See also the description of @samp{-L} in
+@ref{Options,,Command Line Options}.
If you use @samp{INPUT (-l@var{file})}, @command{ld} will transform the
name to @code{lib@var{file}.a}, as with the command line argument
command-line option: to make @code{ld} omit the assignment of addresses
to common symbols even for a non-relocatable output file.
+@item FORCE_GROUP_ALLOCATION
+@kindex FORCE_GROUP_ALLOCATION
+@cindex group allocation in linker script
+@cindex section groups
+@cindex COMDAT
+This command has the same effect as the
+@samp{--force-group-allocation} command-line option: to make
+@command{ld} place section group members like normal input sections,
+and to delete the section groups even if a relocatable output file is
+specified (@samp{-r}).
+
@item INSERT [ AFTER | BEFORE ] @var{output_section}
@kindex INSERT
@cindex insert user script into default script
@end group
@end smallexample
+If an output section's name is the same as the input section's name
+and is representable as a C identifier, then the linker will
+automatically @pxref{PROVIDE} two symbols: __start_SECNAME and
+__stop_SECNAME, where SECNAME is the name of the section. These
+indicate the start address and end address of the output section
+respectively. Note: most section names are not representable as
+C identifiers because they contain a @samp{.} character.
+
@node Output Section Data
@subsection Output Section Data
@cindex data
(@pxref{Options,,Command Line Options}) can be used to control which
output sections an orphan is placed in.
-If an orphaned section's name is representable as a C identifier then
-the linker will automatically @pxref{PROVIDE} two symbols:
-__start_SECNAME and __stop_SECNAME, where SECNAME is the name of the
-section. These indicate the start address and end address of the
-orphaned section respectively. Note: most section names are not
-representable as C identifiers because they contain a @samp{.}
-character.
-
@node Location Counter
@subsection The Location Counter
@kindex .
@ifset POWERPC64
* PowerPC64 ELF64:: @command{ld} and PowerPC64 64-bit ELF Support
@end ifset
+@ifset S/390
+* S/390 ELF:: @command{ld} and S/390 ELF Support
+@end ifset
@ifset SPU
* SPU ELF:: @command{ld} and SPU ELF Support
@end ifset
looks for calls to commonly used functions that create threads, and if
seen, adds the necessary barriers. Use these options to change the
default behaviour.
+
+@cindex PowerPC64 ELFv2 PLT localentry optimization
+@kindex --plt-localentry
+@kindex --no-plt-localentry
+@item --plt-localentry
+@itemx --no-localentry
+ELFv2 functions with localentry:0 are those with a single entry point,
+ie. global entry == local entry, and that have no requirement on r2
+(the TOC/GOT pointer) or r12, and guarantee r2 is unchanged on return.
+Such an external function can be called via the PLT without saving r2
+or restoring it on return, avoiding a common load-hit-store for small
+functions. The optimization is attractive, with up to 40% reduction
+in execution time for a small function, but can result in symbol
+interposition failures. Also, minor changes in a shared library,
+including system libraries, can cause a function that was localentry:0
+to become localentry:8. This will result in a dynamic loader
+complaint and failure to run. The option is experimental, use with
+care. @option{--no-plt-localentry} is the default.
+@end table
+
+@ifclear GENERIC
+@lowersections
+@end ifclear
+@end ifset
+
+@ifset S/390
+@ifclear GENERIC
+@raisesections
+@end ifclear
+
+@node S/390 ELF
+@section @command{ld} and S/390 ELF Support
+
+@cindex S/390 ELF options
+@table @option
+
+@cindex S/390
+@kindex --s390-pgste
+@item --s390-pgste
+This option marks the result file with a @code{PT_S390_PGSTE}
+segment. The Linux kernel is supposed to allocate 4k page tables for
+binaries marked that way.
@end table
@ifclear GENERIC
@code{PRIVATE}: Put the symbol in the DLL's export table, but do not put
it into the static import library used to resolve imports at link time. The
symbol can still be imported using the @code{LoadLibrary/GetProcAddress}
-API at runtime or by by using the GNU ld extension of linking directly to
+API at runtime or by using the GNU ld extension of linking directly to
the DLL without an import library.
See ld/deffilep.y in the binutils sources for the full specification of
projects / deliverable / binutils-gdb.git / blobdiff