\input texinfo
@setfilename ld.info
@c Copyright 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000,
-@c 2001 Free Software Foundation, Inc.
+@c 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
+@c Free Software Foundation, Inc.
@syncodeindex ky cp
+@c man begin INCLUDE
@include configdoc.texi
@c (configdoc.texi is generated by the Makefile)
-@include ldver.texi
+@include bfdver.texi
+@c man end
@c @smallbook
+@macro gcctabopt{body}
+@code{\body\}
+@end macro
+
@c man begin NAME
@ifset man
@c Configure for the generation of man pages
@set UsesEnvVars
@set GENERIC
-@set A29K
-@set ARC
@set ARM
-@set D10V
-@set D30V
-@set H8/300
-@set H8/500
+@set H8300
@set HPPA
-@set I370
-@set I80386
-@set I860
@set I960
-@set M32R
@set M68HC11
-@set M680X0
-@set MCORE
-@set MIPS
-@set PDP11
-@set PJ
-@set SH
-@set SPARC
-@set C54X
-@set V850
-@set VAX
+@set M68K
+@set MMIX
+@set MSP430
+@set POWERPC
+@set POWERPC64
+@set Renesas
+@set SPU
+@set TICOFF
+@set WIN32
+@set XTENSA
@end ifset
@c man end
@end format
@end ifinfo
-@ifinfo
-This file documents the @sc{gnu} linker LD version @value{VERSION}.
-
-Copyright (C) 1991, 92, 93, 94, 95, 96, 97, 98, 99, 2000,
-2001 Free Software Foundation, Inc.
+@copying
+This file documents the @sc{gnu} linker LD
+@ifset VERSION_PACKAGE
+@value{VERSION_PACKAGE}
+@end ifset
+version @value{VERSION}.
-@ignore
+Copyright @copyright{} 1991, 92, 93, 94, 95, 96, 97, 98, 99, 2000,
+2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009 Free Software Foundation, Inc.
Permission is granted to copy, distribute and/or modify this document
-under the terms of the GNU Free Documentation License, Version 1.1
+under the terms of the GNU Free Documentation License, Version 1.3
or any later version published by the Free Software Foundation;
with no Invariant Sections, with no Front-Cover Texts, and with no
Back-Cover Texts. A copy of the license is included in the
-section entitled "GNU Free Documentation License".
-
-Permission is granted to process this file through Tex and print the
-results, provided the printed document carries 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
-@end ifinfo
+section entitled ``GNU Free Documentation License''.
+@end copying
@iftex
@finalout
@setchapternewpage odd
-@settitle Using LD, the GNU linker
+@settitle The GNU linker
@titlepage
-@title Using ld
-@subtitle The GNU linker
+@title The GNU linker
@sp 1
-@subtitle @code{ld} version 2
+@subtitle @code{ld}
+@ifset VERSION_PACKAGE
+@subtitle @value{VERSION_PACKAGE}
+@end ifset
@subtitle Version @value{VERSION}
@author Steve Chamberlain
@author Ian Lance Taylor
{\parskip=0pt
\hfill Red Hat Inc\par
\hfill nickc\@credhat.com, doc\@redhat.com\par
-\hfill {\it Using LD, the GNU linker}\par
+\hfill {\it The GNU linker}\par
\hfill Edited by Jeffrey Osier (jeffrey\@cygnus.com)\par
}
\global\parindent=0pt % Steve likes it this way.
@vskip 0pt plus 1filll
@c man begin COPYRIGHT
-Copyright @copyright{} 1991, 92, 93, 94, 95, 96, 97, 98, 99, 2000 Free Software Foundation, Inc.
+Copyright @copyright{} 1991, 92, 93, 94, 95, 96, 97, 98, 99, 2000, 2001,
+2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009 Free Software Foundation, Inc.
Permission is granted to copy, distribute and/or modify this document
-under the terms of the GNU Free Documentation License, Version 1.1
+under the terms of the GNU Free Documentation License, Version 1.3
or any later version published by the Free Software Foundation;
with no Invariant Sections, with no Front-Cover Texts, and with no
Back-Cover Texts. A copy of the license is included in the
-section entitled "GNU Free Documentation License".
+section entitled ``GNU Free Documentation License''.
@c man end
@end titlepage
@end iftex
+@contents
@c FIXME: Talk about importance of *order* of args, cmds to linker!
-@ifinfo
+@ifnottex
@node Top
-@top Using ld
-This file documents the @sc{gnu} linker ld version @value{VERSION}.
+@top LD
+This file documents the @sc{gnu} linker ld
+@ifset VERSION_PACKAGE
+@value{VERSION_PACKAGE}
+@end ifset
+version @value{VERSION}.
This document is distributed under the terms of the GNU Free
-Documentation License. A copy of the license is included in the
-section entitled "GNU Free Documentation License".
+Documentation License version 1.3. A copy of the license is included
+in the section entitled ``GNU Free Documentation License''.
@menu
* Overview:: Overview
@ifset H8300
* H8/300:: ld and the H8/300
@end ifset
-@ifset Hitachi
-* Hitachi:: ld and other Hitachi micros
+@ifset Renesas
+* Renesas:: ld and other Renesas micros
@end ifset
@ifset I960
* i960:: ld and the Intel 960 family
@end ifset
+@ifset ARM
+* ARM:: ld and the ARM family
+@end ifset
+@ifset HPPA
+* HPPA ELF32:: ld and HPPA 32-bit ELF
+@end ifset
+@ifset M68HC11
+* M68HC11/68HC12:: ld and the Motorola 68HC11 and 68HC12 families
+@end ifset
+@ifset M68K
+* M68K:: ld and Motorola 68K family
+@end ifset
+@ifset POWERPC
+* PowerPC ELF32:: ld and PowerPC 32-bit ELF Support
+@end ifset
+@ifset POWERPC64
+* PowerPC64 ELF64:: ld and PowerPC64 64-bit ELF Support
+@end ifset
+@ifset SPU
+* SPU ELF:: ld and SPU ELF Support
+@end ifset
@ifset TICOFF
* TI COFF:: ld and the TI COFF
@end ifset
+@ifset WIN32
+* Win32:: ld and WIN32 (cygwin/mingw)
+@end ifset
+@ifset XTENSA
+* Xtensa:: ld and Xtensa Processors
+@end ifset
@end ifclear
@ifclear SingleFormat
* BFD:: BFD
* Reporting Bugs:: Reporting Bugs
* MRI:: MRI Compatible Script Files
* GNU Free Documentation License:: GNU Free Documentation License
-* Index:: Index
+* LD Index:: LD Index
@end menu
-@end ifinfo
+@end ifnottex
@node Overview
@chapter Overview
@ifset man
@c man begin SYNOPSIS
-ld [ options ] objfile...
+ld [@b{options}] @var{objfile} @dots{}
@c man end
@c man begin SEEALSO
@c man begin DESCRIPTION
-@code{ld} combines a number of object and archive files, relocates
+@command{ld} combines a number of object and archive files, relocates
their data and ties up symbol references. Usually the last step in
-compiling a program is to run @code{ld}.
+compiling a program is to run @command{ld}.
-@code{ld} accepts Linker Command Language files written in
+@command{ld} accepts Linker Command Language files written in
a superset of AT&T's Link Editor Command Language syntax,
to provide explicit and total control over the linking process.
@ifset man
@c For the man only
-This man page does not describe the command language; see the
-@code{ld} entry in @code{info}, or the manual
-ld: the GNU linker, for full details on the command language and
-on other aspects of the GNU linker.
+This man page does not describe the command language; see the
+@command{ld} entry in @code{info} for full details on the command
+language and on other aspects of the GNU linker.
@end ifset
@ifclear SingleFormat
-This version of @code{ld} uses the general purpose BFD libraries
-to operate on object files. This allows @code{ld} to read, combine, and
+This version of @command{ld} uses the general purpose BFD libraries
+to operate on object files. This allows @command{ld} to read, combine, and
write object files in many different formats---for example, COFF or
@code{a.out}. Different formats may be linked together to produce any
available kind of object file. @xref{BFD}, for more information.
Aside from its flexibility, the @sc{gnu} linker is more helpful than other
linkers in providing diagnostic information. Many linkers abandon
execution immediately upon encountering an error; whenever possible,
-@code{ld} continues executing, allowing you to identify other errors
+@command{ld} continues executing, allowing you to identify other errors
(or, in some cases, to get an output file in spite of the error).
@c man end
@c man begin DESCRIPTION
-The @sc{gnu} linker @code{ld} is meant to cover a broad range of situations,
+The @sc{gnu} linker @command{ld} is meant to cover a broad range of situations,
and to be as compatible as possible with other linkers. As a result,
you have many choices to control its behavior.
The linker supports a plethora of command-line options, but in actual
practice few of them are used in any particular context.
@cindex standard Unix system
-For instance, a frequent use of @code{ld} is to link standard Unix
+For instance, a frequent use of @command{ld} is to link standard Unix
object files on a standard, supported Unix system. On such a system, to
link a file @code{hello.o}:
ld -o @var{output} /lib/crt0.o hello.o -lc
@end smallexample
-This tells @code{ld} to produce a file called @var{output} as the
+This tells @command{ld} to produce a file called @var{output} as the
result of linking the file @code{/lib/crt0.o} with @code{hello.o} and
the library @code{libc.a}, which will come from the standard search
directories. (See the discussion of the @samp{-l} option below.)
-Some of the command-line options to @code{ld} may be specified at any
+Some of the command-line options to @command{ld} may be specified at any
point in the command line. However, options which refer to files, such
as @samp{-l} or @samp{-T}, cause the file to be read at the point at
which the option appears in the command line, relative to the object
are specified, the linker does not produce any output, and issues the
message @samp{No input files}.
-If the linker can not recognize the format of an object file, it will
+If the linker cannot recognize the format of an object file, it will
assume that it is a linker script. A script specified in this way
augments the main linker script used for the link (either the default
linker script or the one specified by using @samp{-T}). This feature
permits the linker to link against a file which appears to be an object
or an archive, but actually merely defines some symbol values, or uses
-@code{INPUT} or @code{GROUP} to load other objects. Note that
-specifying a script in this way should only be used to augment the main
-linker script; if you want to use some command that logically can only
-appear once, such as the @code{SECTIONS} or @code{MEMORY} command, you
-must replace the default linker script using the @samp{-T} option.
-@xref{Scripts}.
+@code{INPUT} or @code{GROUP} to load other objects. Specifying a
+script in this way merely augments the main linker script, with the
+extra commands placed after the main script; use the @samp{-T} option
+to replace the default linker script entirely, but note the effect of
+the @code{INSERT} command. @xref{Scripts}.
For options whose names are a single letter,
option arguments must either follow the option letter without intervening
For options whose names are multiple letters, either one dash or two can
precede the option name; for example, @samp{-trace-symbol} and
-@samp{--trace-symbol} are equivalent. Note - there is one exception to
+@samp{--trace-symbol} are equivalent. Note---there is one exception to
this rule. Multiple letter options that start with a lower case 'o' can
-only be preceeded by two dashes. This is to reduce confusion with the
+only be preceded by two dashes. This is to reduce confusion with the
@samp{-o} option. So for example @samp{-omagic} sets the output file
name to @samp{magic} whereas @samp{--omagic} sets the NMAGIC flag on the
output.
Unique abbreviations of the names of multiple-letter options are
accepted.
-Note - if the linker is being invoked indirectly, via a compiler driver
-(eg @samp{gcc}) then all the linker command line options should be
+Note---if the linker is being invoked indirectly, via a compiler driver
+(e.g. @samp{gcc}) then all the linker command line options should be
prefixed by @samp{-Wl,} (or whatever is appropriate for the particular
compiler driver) like this:
@smallexample
- gcc -Wl,--startgroup foo.o bar.o -Wl,--endgroup
+ gcc -Wl,--start-group foo.o bar.o -Wl,--end-group
@end smallexample
This is important, because otherwise the compiler driver program may
-silently drop the linker options, resulting in a bad link.
+silently drop the linker options, resulting in a bad link. Confusion
+may also arise when passing options that require values through a
+driver, as the use of a space between option and argument acts as
+a separator, and causes the driver to pass only the option to the linker
+and the argument to the compiler. In this case, it is simplest to use
+the joined forms of both single- and multiple-letter options, such as:
+
+@smallexample
+ gcc foo.o bar.o -Wl,-eENTRY -Wl,-Map=a.map
+@end smallexample
Here is a table of the generic command line switches accepted by the GNU
linker:
-@table @code
-@kindex -a@var{keyword}
-@item -a@var{keyword}
+@table @gcctabopt
+@include at-file.texi
+
+@kindex -a @var{keyword}
+@item -a @var{keyword}
This option is supported for HP/UX compatibility. The @var{keyword}
argument must be one of the strings @samp{archive}, @samp{shared}, or
@samp{default}. @samp{-aarchive} is functionally equivalent to
@ifset I960
@cindex architectures
-@kindex -A@var{arch}
-@item -A@var{architecture}
+@kindex -A @var{arch}
+@item -A @var{architecture}
@kindex --architecture=@var{arch}
@itemx --architecture=@var{architecture}
-In the current release of @code{ld}, this option is useful only for the
-Intel 960 family of architectures. In that @code{ld} configuration, the
+In the current release of @command{ld}, this option is useful only for the
+Intel 960 family of architectures. In that @command{ld} configuration, the
@var{architecture} argument identifies the particular architecture in
the 960 family, enabling some safeguards and modifying the
-archive-library search path. @xref{i960,,@code{ld} and the Intel 960
+archive-library search path. @xref{i960,,@command{ld} and the Intel 960
family}, for details.
-Future releases of @code{ld} may support similar functionality for
+Future releases of @command{ld} may support similar functionality for
other architecture families.
@end ifset
@cindex input format
@item -b @var{input-format}
@itemx --format=@var{input-format}
-@code{ld} may be configured to support more than one kind of object
-file. If your @code{ld} is configured this way, you can use the
+@command{ld} may be configured to support more than one kind of object
+file. If your @command{ld} is configured this way, you can use the
@samp{-b} option to specify the binary format for input object files
-that follow this option on the command line. Even when @code{ld} is
+that follow this option on the command line. Even when @command{ld} is
configured to support alternative object formats, you don't usually need
-to specify this, as @code{ld} should be configured to expect as a
+to specify this, as @command{ld} should be configured to expect as a
default input format the most usual format on each machine.
@var{input-format} is a text string, the name of a particular format
supported by the BFD libraries. (You can list the available binary
@cindex compatibility, MRI
@item -c @var{MRI-commandfile}
@itemx --mri-script=@var{MRI-commandfile}
-For compatibility with linkers produced by MRI, @code{ld} accepts script
+For compatibility with linkers produced by MRI, @command{ld} accepts script
files written in an alternate, restricted command language, described in
@ifclear man
@ref{MRI,,MRI Compatible Script Files}.
@end ifset
Introduce MRI script files with
the option @samp{-c}; use the @samp{-T} option to run linker
-scripts written in the general-purpose @code{ld} scripting language.
-If @var{MRI-cmdfile} does not exist, @code{ld} looks for it in the directories
+scripts written in the general-purpose @command{ld} scripting language.
+If @var{MRI-cmdfile} does not exist, @command{ld} looks for it in the directories
specified by any @samp{-L} options.
@cindex common allocation
@samp{0} for base 8). @xref{Entry Point}, for a discussion of defaults
and other ways of specifying the entry point.
+@kindex --exclude-libs
+@item --exclude-libs @var{lib},@var{lib},...
+Specifies a list of archive libraries from which symbols should not be automatically
+exported. The library names may be delimited by commas or colons. Specifying
+@code{--exclude-libs ALL} excludes symbols in all archive libraries from
+automatic export. This option is available only for the i386 PE targeted
+port of the linker and for ELF targeted ports. For i386 PE, symbols
+explicitly listed in a .def file are still exported, regardless of this
+option. For ELF targeted ports, symbols affected by this option will
+be treated as hidden.
+
+@kindex --exclude-modules-for-implib
+@item --exclude-modules-for-implib @var{module},@var{module},...
+Specifies a list of object files or archive members, from which symbols
+should not be automatically exported, but which should be copied wholesale
+into the import library being generated during the link. The module names
+may be delimited by commas or colons, and must match exactly the filenames
+used by @command{ld} to open the files; for archive members, this is simply
+the member name, but for object files the name listed must include and
+match precisely any path used to specify the input file on the linker's
+command-line. This option is available only for the i386 PE targeted port
+of the linker. Symbols explicitly listed in a .def file are still exported,
+regardless of this option.
+
@cindex dynamic symbol table
@kindex -E
@kindex --export-dynamic
dynamic object, then you will probably need to use this option when
linking the program itself.
-You can also use the version script to control what symbols should
+You can also use the dynamic list to control what symbols should
be added to the dynamic symbol table if the output format supports it.
-See the description of @samp{--version-script} in @ref{VERSION}.
+See the description of @samp{--dynamic-list}.
+@ifclear SingleFormat
@cindex big-endian objects
@cindex endianness
@kindex -EB
@kindex -EL
@item -EL
Link little-endian objects. This affects the default output format.
+@end ifclear
-@kindex -f
-@kindex --auxiliary
-@item -f
-@itemx --auxiliary @var{name}
+@kindex -f @var{name}
+@kindex --auxiliary=@var{name}
+@item -f @var{name}
+@itemx --auxiliary=@var{name}
When creating an ELF shared object, set the internal DT_AUXILIARY field
to the specified name. This tells the dynamic linker that the symbol
table of the shared object should be used as an auxiliary filter on the
This option may be specified more than once. The DT_AUXILIARY entries
will be created in the order in which they appear on the command line.
-@kindex -F
-@kindex --filter
+@kindex -F @var{name}
+@kindex --filter=@var{name}
@item -F @var{name}
-@itemx --filter @var{name}
+@itemx --filter=@var{name}
When creating an ELF shared object, set the internal DT_FILTER field to
the specified name. This tells the dynamic linker that the symbol table
of the shared object which is being created should be used as a filter
used to select a subset of the symbols provided by the object
@var{name}.
-Some older linkers used the @code{-F} option throughout a compilation
+Some older linkers used the @option{-F} option throughout a compilation
toolchain for specifying object-file format for both input and output
-object files. The @sc{gnu} linker uses other mechanisms for this
-purpose: the @code{-b}, @code{--format}, @code{--oformat} options, the
+object files.
+@ifclear SingleFormat
+The @sc{gnu} linker uses other mechanisms for this purpose: the
+@option{-b}, @option{--format}, @option{--oformat} options, the
@code{TARGET} command in linker scripts, and the @code{GNUTARGET}
-environment variable. The @sc{gnu} linker will ignore the @code{-F}
-option when not creating an ELF shared object.
+environment variable.
+@end ifclear
+The @sc{gnu} linker will ignore the @option{-F} option when not
+creating an ELF shared object.
@cindex finalization function
-@kindex -fini
-@item -fini @var{name}
+@kindex -fini=@var{name}
+@item -fini=@var{name}
When creating an ELF executable or shared object, call NAME when the
executable or shared object is unloaded, by setting DT_FINI to the
address of the function. By default, the linker uses @code{_fini} as
@item -g
Ignored. Provided for compatibility with other tools.
-@kindex -G
-@kindex --gpsize
+@kindex -G @var{value}
+@kindex --gpsize=@var{value}
@cindex object size
-@item -G@var{value}
+@item -G @var{value}
@itemx --gpsize=@var{value}
Set the maximum size of objects to be optimized using the GP register to
@var{size}. This is only meaningful for object file formats such as
sections. This is ignored for other object file formats.
@cindex runtime library name
-@kindex -h@var{name}
+@kindex -h @var{name}
@kindex -soname=@var{name}
-@item -h@var{name}
+@item -h @var{name}
@itemx -soname=@var{name}
When creating an ELF shared object, set the internal DT_SONAME field to
the specified name. When an executable is linked with a shared object
Perform an incremental link (same as option @samp{-r}).
@cindex initialization function
-@kindex -init
-@item -init @var{name}
+@kindex -init=@var{name}
+@item -init=@var{name}
When creating an ELF executable or shared object, call NAME when the
executable or shared object is loaded, by setting DT_INIT to the address
of the function. By default, the linker uses @code{_init} as the
function to call.
@cindex archive files, from cmd line
-@kindex -l@var{archive}
-@kindex --library=@var{archive}
-@item -l@var{archive}
-@itemx --library=@var{archive}
-Add archive file @var{archive} to the list of files to link. This
-option may be used any number of times. @code{ld} will search its
-path-list for occurrences of @code{lib@var{archive}.a} for every
-@var{archive} specified.
-
-On systems which support shared libraries, @code{ld} may also search for
-libraries with extensions other than @code{.a}. Specifically, on ELF
-and SunOS systems, @code{ld} will search a directory for a library with
-an extension of @code{.so} before searching for one with an extension of
-@code{.a}. By convention, a @code{.so} extension indicates a shared
-library.
+@kindex -l @var{namespec}
+@kindex --library=@var{namespec}
+@item -l @var{namespec}
+@itemx --library=@var{namespec}
+Add the archive or object file specified by @var{namespec} to the
+list of files to link. This option may be used any number of times.
+If @var{namespec} is of the form @file{:@var{filename}}, @command{ld}
+will search the library path for a file called @var{filename}, otherise it
+will search the library path for a file called @file{lib@var{namespec}.a}.
+
+On systems which support shared libraries, @command{ld} may also search for
+files other than @file{lib@var{namespec}.a}. Specifically, on ELF
+and SunOS systems, @command{ld} will search a directory for a library
+called @file{lib@var{namespec}.so} before searching for one called
+@file{lib@var{namespec}.a}. (By convention, a @code{.so} extension
+indicates a shared library.) Note that this behavior does not apply
+to @file{:@var{filename}}, which always specifies a file called
+@var{filename}.
The linker will search an archive only once, at the location where it is
specified on the command line. If the archive defines a symbol which
archive. However, an undefined symbol in an object appearing later on
the command line will not cause the linker to search the archive again.
-See the @code{-(} option for a way to force the linker to search
+See the @option{-(} option for a way to force the linker to search
archives multiple times.
You may list the same archive multiple times on the command line.
@ifset GENERIC
This type of archive searching is standard for Unix linkers. However,
-if you are using @code{ld} on AIX, note that it is different from the
+if you are using @command{ld} on AIX, note that it is different from the
behaviour of the AIX linker.
@end ifset
@cindex search directory, from cmd line
-@kindex -L@var{dir}
+@kindex -L @var{dir}
@kindex --library-path=@var{dir}
-@item -L@var{searchdir}
+@item -L @var{searchdir}
@itemx --library-path=@var{searchdir}
-Add path @var{searchdir} to the list of paths that @code{ld} will search
-for archive libraries and @code{ld} control scripts. You may use this
+Add path @var{searchdir} to the list of paths that @command{ld} will search
+for archive libraries and @command{ld} control scripts. You may use this
option any number of times. The directories are searched in the order
in which they are specified on the command line. Directories specified
on the command line are searched before the default directories. All
-@code{-L} options apply to all @code{-l} options, regardless of the
+@option{-L} options apply to all @option{-l} options, regardless of the
order in which the options appear.
+If @var{searchdir} begins with @code{=}, then the @code{=} will be replaced
+by the @dfn{sysroot prefix}, a path specified when the linker is configured.
+
@ifset UsesEnvVars
The default set of paths searched (without being specified with
-@samp{-L}) depends on which emulation mode @code{ld} is using, and in
+@samp{-L}) depends on which emulation mode @command{ld} is using, and in
some cases also on how it was configured. @xref{Environment}.
@end ifset
@cindex emulation
@kindex -m @var{emulation}
-@item -m@var{emulation}
+@item -m @var{emulation}
Emulate the @var{emulation} linker. You can list the available
emulations with the @samp{--verbose} or @samp{-V} options.
@itemize @bullet
@item
-Where object files and symbols are mapped into memory.
+Where object files are mapped into memory.
@item
How common symbols are allocated.
@item
All archive members included in the link, with a mention of the symbol
which caused the archive member to be brought in.
+@item
+The values assigned to symbols.
+
+Note - symbols whose values are computed by an expression which
+involves a reference to a previous value of the same symbol may not
+have correct result displayed in the link map. This is because the
+linker discards intermediate results and only retains the final value
+of an expression. Under such circumstances the linker will display
+the final value enclosed by square brackets. Thus for example a
+linker script containing:
+
+@smallexample
+ foo = 1
+ foo = foo * 4
+ foo = foo + 8
+@end smallexample
+
+will produce the following output in the link map if the @option{-M}
+option is used:
+
+@smallexample
+ 0x00000001 foo = 0x1
+ [0x0000000c] foo = (foo * 0x4)
+ [0x0000000c] foo = (foo + 0x8)
+@end smallexample
+
+See @ref{Expressions} for more information about expressions in linker
+scripts.
@end itemize
@kindex -n
@item -N
@itemx --omagic
Set the text and data sections to be readable and writable. Also, do
-not page-align the data segment. If the output format supports Unix
-style magic numbers, mark the output as @code{OMAGIC}.
+not page-align the data segment, and disable linking against shared
+libraries. If the output format supports Unix style magic numbers,
+mark the output as @code{OMAGIC}. Note: Although a writable text section
+is allowed for PE-COFF targets, it does not conform to the format
+specification published by Microsoft.
+
+@kindex --no-omagic
+@cindex OMAGIC
+@item --no-omagic
+This option negates most of the effects of the @option{-N} option. It
+sets the text section to be read-only, and forces the data segment to
+be page-aligned. Note - this option does not enable linking against
+shared libraries. Use @option{-Bdynamic} for this.
@kindex -o @var{output}
@kindex --output=@var{output}
@cindex naming the output file
@item -o @var{output}
@itemx --output=@var{output}
-Use @var{output} as the name for the program produced by @code{ld}; if this
+Use @var{output} as the name for the program produced by @command{ld}; if this
option is not specified, the name @file{a.out} is used by default. The
script command @code{OUTPUT} can also specify the output file name.
@kindex -O @var{level}
@cindex generating optimized output
@item -O @var{level}
-If @var{level} is a numeric values greater than zero @code{ld} optimizes
+If @var{level} is a numeric values greater than zero @command{ld} optimizes
the output. This might take significantly longer and therefore probably
-should only be enabled for the final binary.
+should only be enabled for the final binary. At the moment this
+option only affects ELF shared library generation. Future releases of
+the linker may make more use of this option. Also currently there is
+no difference in the linker's behaviour for different non-zero values
+of this option. Again this may change with future releases.
@kindex -q
@kindex --emit-relocs
@cindex retain relocations in final executable
@item -q
@itemx --emit-relocs
-Leave relocation sections and contents in fully linked exececutables.
+Leave relocation sections and contents in fully linked executables.
Post link analysis and optimization tools may need this information in
order to perform correct modifications of executables. This results
in larger executables.
+This option is currently only supported on ELF platforms.
+
+@kindex --force-dynamic
+@cindex forcing the creation of dynamic sections
+@item --force-dynamic
+Force the output file to have dynamic sections. This option is specific
+to VxWorks targets.
+
@cindex partial link
@cindex relocatable output
@kindex -r
-@kindex --relocateable
+@kindex --relocatable
@item -r
-@itemx --relocateable
+@itemx --relocatable
Generate relocatable output---i.e., generate an output file that can in
-turn serve as input to @code{ld}. This is often called @dfn{partial
+turn serve as input to @command{ld}. This is often called @dfn{partial
linking}. As a side effect, in environments that support standard Unix
magic numbers, this option also sets the output file's magic number to
@code{OMAGIC}.
-@c ; see @code{-N}.
+@c ; see @option{-N}.
If this option is not specified, an absolute file is produced. When
linking C++ programs, this option @emph{will not} resolve references to
constructors; to do that, use @samp{-Ur}.
to refer symbolically to absolute locations of memory defined in other
programs. You may use this option more than once.
-For compatibility with other ELF linkers, if the @code{-R} option is
+For compatibility with other ELF linkers, if the @option{-R} option is
followed by a directory name, rather than a file name, it is treated as
-the @code{-rpath} option.
+the @option{-rpath} option.
@kindex -s
@kindex --strip-all
@cindex input files, displaying
@item -t
@itemx --trace
-Print the names of the input files as @code{ld} processes them.
+Print the names of the input files as @command{ld} processes them.
@kindex -T @var{script}
@kindex --script=@var{script}
@item -T @var{scriptfile}
@itemx --script=@var{scriptfile}
Use @var{scriptfile} as the linker script. This script replaces
-@code{ld}'s default linker script (rather than adding to it), so
+@command{ld}'s default linker script (rather than adding to it), so
@var{commandfile} must specify everything necessary to describe the
-output file. You must use this option if you want to use a command
-which can only appear once in a linker script, such as the
-@code{SECTIONS} or @code{MEMORY} command. @xref{Scripts}. If
-@var{scriptfile} does not exist in the current directory, @code{ld}
-looks for it in the directories specified by any preceding @samp{-L}
-options. Multiple @samp{-T} options accumulate.
+output file. @xref{Scripts}. If @var{scriptfile} does not exist in
+the current directory, @code{ld} looks for it in the directories
+specified by any preceding @samp{-L} options. Multiple @samp{-T}
+options accumulate.
+
+@kindex -dT @var{script}
+@kindex --default-script=@var{script}
+@cindex script files
+@item -dT @var{scriptfile}
+@itemx --default-script=@var{scriptfile}
+Use @var{scriptfile} as the default linker script. @xref{Scripts}.
+
+This option is similar to the @option{--script} option except that
+processing of the script is delayed until after the rest of the
+command line has been processed. This allows options placed after the
+@option{--default-script} option on the command line to affect the
+behaviour of the linker script, which can be important when the linker
+command line cannot be directly controlled by the user. (eg because
+the command line is being constructed by another tool, such as
+@samp{gcc}).
@kindex -u @var{symbol}
@kindex --undefined=@var{symbol}
@item -Ur
For anything other than C++ programs, this option is equivalent to
@samp{-r}: it generates relocatable output---i.e., an output file that can in
-turn serve as input to @code{ld}. When linking C++ programs, @samp{-Ur}
+turn serve as input to @command{ld}. When linking C++ programs, @samp{-Ur}
@emph{does} resolve references to constructors, unlike @samp{-r}.
It does not work to use @samp{-Ur} on files that were themselves linked
with @samp{-Ur}; once the constructor table has been built, it cannot
@item -v
@itemx --version
@itemx -V
-Display the version number for @code{ld}. The @code{-V} option also
+Display the version number for @command{ld}. The @option{-V} option also
lists the supported emulations.
@kindex -x
@kindex -X
@kindex --discard-locals
@cindex local symbols, deleting
-@cindex L, deleting symbols beginning
@item -X
@itemx --discard-locals
-Delete all temporary local symbols. For most targets, this is all local
-symbols whose names begin with @samp{L}.
+Delete all temporary local symbols. (These symbols start with
+system-specific local label prefixes, typically @samp{.L} for ELF systems
+or @samp{L} for traditional a.out systems.)
@kindex -y @var{symbol}
@kindex --trace-symbol=@var{symbol}
@kindex -z @var{keyword}
@item -z @var{keyword}
-The recognized keywords are @code{initfirst}, @code{interpose},
-@code{loadfltr}, @code{nodefaultlib}, @code{nodelete}, @code{nodlopen},
-@code{nodump}, @code{now} and @code{origin}. The other keywords are
-ignored for Solaris compatibility. @code{initfirst} marks the object
-to be initialized first at runtime before any other objects.
-@code{interpose} marks the object that its symbol table interposes
-before all symbols but the primary executable. @code{loadfltr} marks
-the object that its filtees be processed immediately at runtime.
-@code{nodefaultlib} marks the object that the search for dependencies
-of this object will ignore any default library search paths.
-@code{nodelete} marks the object shouldn't be unloaded at runtime.
-@code{nodlopen} marks the object not available to @code{dlopen}.
-@code{nodump} marks the object can not be dumped by @code{dldump}.
-@code{now} marks the object with the non-lazy runtime binding.
-@code{origin} marks the object may contain $ORIGIN.
-@code{defs} disallows undefined symbols.
+The recognized keywords are:
+@table @samp
+
+@item combreloc
+Combines multiple reloc sections and sorts them to make dynamic symbol
+lookup caching possible.
+
+@item defs
+Disallows undefined symbols in object files. Undefined symbols in
+shared libraries are still allowed.
+
+@item execstack
+Marks the object as requiring executable stack.
+
+@item initfirst
+This option is only meaningful when building a shared object.
+It marks the object so that its runtime initialization will occur
+before the runtime initialization of any other objects brought into
+the process at the same time. Similarly the runtime finalization of
+the object will occur after the runtime finalization of any other
+objects.
+
+@item interpose
+Marks the object that its symbol table interposes before all symbols
+but the primary executable.
+
+@item lazy
+When generating an executable or shared library, mark it to tell the
+dynamic linker to defer function call resolution to the point when
+the function is called (lazy binding), rather than at load time.
+Lazy binding is the default.
+
+@item loadfltr
+Marks the object that its filters be processed immediately at
+runtime.
+
+@item muldefs
+Allows multiple definitions.
+
+@item nocombreloc
+Disables multiple reloc sections combining.
+
+@item nocopyreloc
+Disables production of copy relocs.
+
+@item nodefaultlib
+Marks the object that the search for dependencies of this object will
+ignore any default library search paths.
+
+@item nodelete
+Marks the object shouldn't be unloaded at runtime.
+
+@item nodlopen
+Marks the object not available to @code{dlopen}.
+
+@item nodump
+Marks the object can not be dumped by @code{dldump}.
+
+@item noexecstack
+Marks the object as not requiring executable stack.
+
+@item norelro
+Don't create an ELF @code{PT_GNU_RELRO} segment header in the object.
+
+@item now
+When generating an executable or shared library, mark it to tell the
+dynamic linker to resolve all symbols when the program is started, or
+when the shared library is linked to using dlopen, instead of
+deferring function call resolution to the point when the function is
+first called.
+
+@item origin
+Marks the object may contain $ORIGIN.
+
+@item relro
+Create an ELF @code{PT_GNU_RELRO} segment header in the object.
+
+@item max-page-size=@var{value}
+Set the emulation maximum page size to @var{value}.
+
+@item common-page-size=@var{value}
+Set the emulation common page size to @var{value}.
+
+@end table
+
+Other keywords are ignored for Solaris compatibility.
@kindex -(
@cindex groups of archives
it only when there are unavoidable circular references between two or
more archives.
+@kindex --accept-unknown-input-arch
+@kindex --no-accept-unknown-input-arch
+@item --accept-unknown-input-arch
+@itemx --no-accept-unknown-input-arch
+Tells the linker to accept input files whose architecture cannot be
+recognised. The assumption is that the user knows what they are doing
+and deliberately wants to link in these unknown input files. This was
+the default behaviour of the linker, before release 2.14. The default
+behaviour from release 2.14 onwards is to reject such input files, and
+so the @samp{--accept-unknown-input-arch} option has been added to
+restore the old behaviour.
+
+@kindex --as-needed
+@kindex --no-as-needed
+@item --as-needed
+@itemx --no-as-needed
+This option affects ELF DT_NEEDED tags for dynamic libraries mentioned
+on the command line after the @option{--as-needed} option. Normally,
+the linker will add a DT_NEEDED tag for each dynamic library mentioned
+on the command line, regardless of whether the library is actually
+needed. @option{--as-needed} causes a DT_NEEDED tag to only be emitted
+for a library that satisfies a symbol reference from regular objects
+which is undefined at the point that the library was linked, or, if
+the library is not found in the DT_NEEDED lists of other libraries
+linked up to that point, a reference from another dynamic library.
+@option{--no-as-needed} restores the default behaviour.
+
+@kindex --add-needed
+@kindex --no-add-needed
+@item --add-needed
+@itemx --no-add-needed
+This option affects the treatment of dynamic libraries from ELF
+DT_NEEDED tags in dynamic libraries mentioned on the command line after
+the @option{--no-add-needed} option. Normally, the linker will add
+a DT_NEEDED tag for each dynamic library from DT_NEEDED tags.
+@option{--no-add-needed} causes DT_NEEDED tags will never be emitted
+for those libraries from DT_NEEDED tags. @option{--add-needed} restores
+the default behaviour.
+
@kindex -assert @var{keyword}
@item -assert @var{keyword}
This option is ignored for SunOS compatibility.
default on such platforms. The different variants of this option are
for compatibility with various systems. You may use this option
multiple times on the command line: it affects library searching for
-@code{-l} options which follow it.
+@option{-l} options which follow it.
@kindex -Bgroup
@item -Bgroup
Set the @code{DF_1_GROUP} flag in the @code{DT_FLAGS_1} entry in the dynamic
section. This causes the runtime linker to handle lookups in this
object and its dependencies to be performed only inside the group.
-@code{--no-undefined} is implied. This option is only meaningful on ELF
-platforms which support shared libraries.
+@option{--unresolved-symbols=report-all} is implied. This option is
+only meaningful on ELF platforms which support shared libraries.
@kindex -Bstatic
@kindex -dn
platforms for which shared libraries are supported. The different
variants of this option are for compatibility with various systems. You
may use this option multiple times on the command line: it affects
-library searching for @code{-l} options which follow it.
+library searching for @option{-l} options which follow it. This
+option also implies @option{--unresolved-symbols=report-all}. This
+option can be used with @option{-shared}. Doing so means that a
+shared library is being created but that all of the library's external
+references must be resolved by pulling in entries from static
+libraries.
@kindex -Bsymbolic
@item -Bsymbolic
within the shared library. This option is only meaningful on ELF
platforms which support shared libraries.
+@kindex -Bsymbolic-functions
+@item -Bsymbolic-functions
+When creating a shared library, bind references to global function
+symbols to the definition within the shared library, if any.
+This option is only meaningful on ELF platforms which support shared
+libraries.
+
+@kindex --dynamic-list=@var{dynamic-list-file}
+@item --dynamic-list=@var{dynamic-list-file}
+Specify the name of a dynamic list file to the linker. This is
+typically used when creating shared libraries to specify a list of
+global symbols whose references shouldn't be bound to the definition
+within the shared library, or creating dynamically linked executables
+to specify a list of symbols which should be added to the symbol table
+in the executable. This option is only meaningful on ELF platforms
+which support shared libraries.
+
+The format of the dynamic list is the same as the version node without
+scope and node name. See @ref{VERSION} for more information.
+
+@kindex --dynamic-list-data
+@item --dynamic-list-data
+Include all global data symbols to the dynamic list.
+
+@kindex --dynamic-list-cpp-new
+@item --dynamic-list-cpp-new
+Provide the builtin dynamic list for C++ operator new and delete. It
+is mainly useful for building shared libstdc++.
+
+@kindex --dynamic-list-cpp-typeinfo
+@item --dynamic-list-cpp-typeinfo
+Provide the builtin dynamic list for C++ runtime type identification.
+
@kindex --check-sections
@kindex --no-check-sections
@item --check-sections
@itemx --no-check-sections
Asks the linker @emph{not} to check section addresses after they have
-been assigned to see if there any overlaps. Normally the linker will
+been assigned to see if there are any overlaps. Normally the linker will
perform this check, and if it finds any overlaps it will produce
suitable error messages. The linker does know about, and does make
allowances for sections in overlays. The default behaviour can be
-restored by using the command line switch @samp{--check-sections}.
+restored by using the command line switch @option{--check-sections}.
+Section overlap is not usually checked for relocatable links. You can
+force checking in that case by using the @option{--check-sections}
+option.
@cindex cross reference table
@kindex --cref
symbol is defined, the first file listed is the location of the
definition. The remaining files contain references to the symbol.
+@cindex common allocation
+@kindex --no-define-common
+@item --no-define-common
+This option inhibits the assignment of addresses to common symbols.
+The script command @code{INHIBIT_COMMON_ALLOCATION} has the same effect.
+@xref{Miscellaneous Commands}.
+
+The @samp{--no-define-common} option allows decoupling
+the decision to assign addresses to Common symbols from the choice
+of the output file type; otherwise a non-Relocatable output type
+forces assigning addresses to Common symbols.
+Using @samp{--no-define-common} allows Common symbols that are referenced
+from a shared library to be assigned addresses only in the main program.
+This eliminates the unused duplicate space in the shared library,
+and also prevents any possible confusion over resolving to the wrong
+duplicate when there are many dynamic modules with specialized search
+paths for runtime symbol resolution.
+
@cindex symbols, from command line
-@kindex --defsym @var{symbol}=@var{exp}
-@item --defsym @var{symbol}=@var{expression}
+@kindex --defsym=@var{symbol}=@var{exp}
+@item --defsym=@var{symbol}=@var{expression}
Create a global symbol in the output file, containing the absolute
address given by @var{expression}. You may use this option as many
times as necessary to define multiple symbols in the command line. A
@cindex dynamic linker, from command line
@kindex -I@var{file}
-@kindex --dynamic-linker @var{file}
-@item --dynamic-linker @var{file}
+@kindex --dynamic-linker=@var{file}
+@item -I@var{file}
+@itemx --dynamic-linker=@var{file}
Set the name of the dynamic linker. This is only meaningful when
generating dynamically linked ELF executables. The default dynamic
linker is normally correct; don't use this unless you know what you are
doing.
-@cindex MIPS embedded PIC code
-@kindex --embedded-relocs
-@item --embedded-relocs
-This option is only meaningful when linking MIPS embedded PIC code,
-generated by the -membedded-pic option to the @sc{gnu} compiler and
-assembler. It causes the linker to create a table which may be used at
-runtime to relocate any data which was statically initialized to pointer
-values. See the code in testsuite/ld-empic for details.
-
-
@kindex --fatal-warnings
+@kindex --no-fatal-warnings
@item --fatal-warnings
-Treat all warnings as errors.
+@itemx --no-fatal-warnings
+Treat all warnings as errors. The default behaviour can be restored
+with the option @option{--no-fatal-warnings}.
@kindex --force-exe-suffix
@item --force-exe-suffix
@kindex --gc-sections
@kindex --no-gc-sections
@cindex garbage collection
-@item --no-gc-sections
-@itemx --gc-sections
+@item --gc-sections
+@itemx --no-gc-sections
Enable garbage collection of unused input sections. It is ignored on
-targets that do not support this option. This option is not compatible
-with @samp{-r}, nor should it be used with dynamic linking. The default
-behaviour (of not performing this garbage collection) can be restored by
-specifying @samp{--no-gc-sections} on the command line.
+targets that do not support this option. The default behaviour (of not
+performing this garbage collection) can be restored by specifying
+@samp{--no-gc-sections} on the command line.
+
+@samp{--gc-sections} decides which input sections are used by
+examining symbols and relocations. The section containing the entry
+symbol and all sections containing symbols undefined on the
+command-line will be kept, as will sections containing symbols
+referenced by dynamic objects. Note that when building shared
+libraries, the linker must assume that any visible symbol is
+referenced. Once this initial set of sections has been determined,
+the linker recursively marks as used any section referenced by their
+relocations. See @samp{--entry} and @samp{--undefined}.
+
+This option can be set when doing a partial link (enabled with option
+@samp{-r}). In this case the root of symbols kept must be explicitely
+specified either by an @samp{--entry} or @samp{--undefined} option or by
+a @code{ENTRY} command in the linker script.
+
+@kindex --print-gc-sections
+@kindex --no-print-gc-sections
+@cindex garbage collection
+@item --print-gc-sections
+@itemx --no-print-gc-sections
+List all sections removed by garbage collection. The listing is
+printed on stderr. This option is only effective if garbage
+collection has been enabled via the @samp{--gc-sections}) option. The
+default behaviour (of not listing the sections that are removed) can
+be restored by specifying @samp{--no-print-gc-sections} on the command
+line.
@cindex help
@cindex usage
@item --target-help
Print a summary of all target specific options on the standard output and exit.
-@kindex -Map
-@item -Map @var{mapfile}
+@kindex -Map=@var{mapfile}
+@item -Map=@var{mapfile}
Print a link map to the file @var{mapfile}. See the description of the
-@samp{-M} option, above.
+@option{-M} option, above.
@cindex memory usage
@kindex --no-keep-memory
@item --no-keep-memory
-@code{ld} normally optimizes for speed over memory usage by caching the
-symbol tables of input files in memory. This option tells @code{ld} to
+@command{ld} normally optimizes for speed over memory usage by caching the
+symbol tables of input files in memory. This option tells @command{ld} to
instead optimize for memory usage, by rereading the symbol tables as
-necessary. This may be required if @code{ld} runs out of memory space
+necessary. This may be required if @command{ld} runs out of memory space
while linking a large executable.
@kindex --no-undefined
@kindex -z defs
@item --no-undefined
@itemx -z defs
-Normally when creating a non-symbolic shared library, undefined symbols
-are allowed and left to be resolved by the runtime loader. These options
-disallows such undefined symbols.
+Report unresolved symbol references from regular object files. This
+is done even if the linker is creating a non-symbolic shared library.
+The switch @option{--[no-]allow-shlib-undefined} controls the
+behaviour for reporting unresolved references found in shared
+libraries being linked in.
+
+@kindex --allow-multiple-definition
+@kindex -z muldefs
+@item --allow-multiple-definition
+@itemx -z muldefs
+Normally when a symbol is defined multiple times, the linker will
+report a fatal error. These options allow multiple definitions and the
+first definition will be used.
@kindex --allow-shlib-undefined
+@kindex --no-allow-shlib-undefined
@item --allow-shlib-undefined
-Allow undefined symbols in shared objects even when --no-undefined is
-set. The net result will be that undefined symbols in regular objects
-will still trigger an error, but undefined symbols in shared objects
-will be ignored. The implementation of no_undefined makes the
-assumption that the runtime linker will choke on undefined symbols.
-However there is at least one system (BeOS) where undefined symbols in
-shared libraries is normal since the kernel patches them at load time to
-select which function is most appropriate for the current architecture.
-I.E. dynamically select an appropriate memset function. Apparently it
-is also normal for HPPA shared libraries to have undefined symbols.
+@itemx --no-allow-shlib-undefined
+Allows or disallows undefined symbols in shared libraries.
+This switch is similar to @option{--no-undefined} except that it
+determines the behaviour when the undefined symbols are in a
+shared library rather than a regular object file. It does not affect
+how undefined symbols in regular object files are handled.
+
+The default behaviour is to report errors for any undefined symbols
+referenced in shared libraries if the linker is being used to create
+an executable, but to allow them if the linker is being used to create
+a shared library.
+
+The reasons for allowing undefined symbol references in shared
+libraries specified at link time are that:
+
+@itemize @bullet
+@item
+A shared library specified at link time may not be the same as the one
+that is available at load time, so the symbol might actually be
+resolvable at load time.
+@item
+There are some operating systems, eg BeOS and HPPA, where undefined
+symbols in shared libraries are normal.
+
+The BeOS kernel for example patches shared libraries at load time to
+select whichever function is most appropriate for the current
+architecture. This is used, for example, to dynamically select an
+appropriate memset function.
+@end itemize
+
+@kindex --no-undefined-version
+@item --no-undefined-version
+Normally when a symbol has an undefined version, the linker will ignore
+it. This option disallows symbols with undefined version and a fatal error
+will be issued instead.
+
+@kindex --default-symver
+@item --default-symver
+Create and use a default symbol version (the soname) for unversioned
+exported symbols.
+
+@kindex --default-imported-symver
+@item --default-imported-symver
+Create and use a default symbol version (the soname) for unversioned
+imported symbols.
@kindex --no-warn-mismatch
@item --no-warn-mismatch
-Normally @code{ld} will give an error if you try to link together input
+Normally @command{ld} will give an error if you try to link together input
files that are mismatched for some reason, perhaps because they have
been compiled for different processors or for different endiannesses.
-This option tells @code{ld} that it should silently permit such possible
+This option tells @command{ld} that it should silently permit such possible
errors. This option should only be used with care, in cases when you
have taken some special action that ensures that the linker errors are
inappropriate.
+@kindex --no-warn-search-mismatch
+@item --no-warn-search-mismatch
+Normally @command{ld} will give a warning if it finds an incompatible
+library during a library search. This option silences the warning.
+
@kindex --no-whole-archive
@item --no-whole-archive
-Turn off the effect of the @code{--whole-archive} option for subsequent
+Turn off the effect of the @option{--whole-archive} option for subsequent
archive files.
@cindex output file after errors
errors during the link process; it exits without writing an output file
when it issues any error whatsoever.
+@kindex -nostdlib
+@item -nostdlib
+Only search library directories explicitly specified on the
+command line. Library directories specified in linker scripts
+(including linker scripts specified on the command line) are ignored.
+
@ifclear SingleFormat
-@kindex --oformat
-@item --oformat @var{output-format}
-@code{ld} may be configured to support more than one kind of object
-file. If your @code{ld} is configured this way, you can use the
+@kindex --oformat=@var{output-format}
+@item --oformat=@var{output-format}
+@command{ld} may be configured to support more than one kind of object
+file. If your @command{ld} is configured this way, you can use the
@samp{--oformat} option to specify the binary format for the output
-object file. Even when @code{ld} is configured to support alternative
-object formats, you don't usually need to specify this, as @code{ld}
+object file. Even when @command{ld} is configured to support alternative
+object formats, you don't usually need to specify this, as @command{ld}
should be configured to produce as a default output format the most
usual format on each machine. @var{output-format} is a text string, the
name of a particular format supported by the BFD libraries. (You can
this option overrides it. @xref{BFD}.
@end ifclear
+@kindex -pie
+@kindex --pic-executable
+@item -pie
+@itemx --pic-executable
+@cindex position independent executables
+Create a position independent executable. This is currently only supported on
+ELF platforms. Position independent executables are similar to shared
+libraries in that they are relocated by the dynamic linker to the virtual
+address the OS chooses for them (which can vary between invocations). Like
+normal dynamically linked executables they can be executed and symbols
+defined in the executable cannot be overridden by shared libraries.
+
@kindex -qmagic
@item -qmagic
This option is ignored for Linux compatibility.
This option is only supported on a few targets.
@end ifset
@ifset H8300
-@xref{H8/300,,@code{ld} and the H8/300}.
+@xref{H8/300,,@command{ld} and the H8/300}.
@end ifset
@ifset I960
-@xref{i960,, @code{ld} and the Intel 960 family}.
+@xref{i960,, @command{ld} and the Intel 960 family}.
+@end ifset
+@ifset XTENSA
+@xref{Xtensa,, @command{ld} and Xtensa Processors}.
+@end ifset
+@ifset M68HC11
+@xref{M68HC11/68HC12,,@command{ld} and the 68HC11 and 68HC12}.
+@end ifset
+@ifset POWERPC
+@xref{PowerPC ELF32,,@command{ld} and PowerPC 32-bit ELF Support}.
@end ifset
-
On some platforms, the @samp{--relax} option performs global
optimizations that become possible when the linker resolves addressing
@cindex retaining specified symbols
@cindex stripping all but some symbols
@cindex symbols, retaining selectively
-@item --retain-symbols-file @var{filename}
+@kindex --retain-symbols-file=@var{filename}
+@item --retain-symbols-file=@var{filename}
Retain @emph{only} the symbols listed in the file @var{filename},
discarding all others. @var{filename} is simply a flat file, with one
symbol name per line. This option is especially useful in environments
line. It overrides @samp{-s} and @samp{-S}.
@ifset GENERIC
-@item -rpath @var{dir}
+@item -rpath=@var{dir}
@cindex runtime library search path
-@kindex -rpath
+@kindex -rpath=@var{dir}
Add a directory to the runtime library search path. This is used when
-linking an ELF executable with shared objects. All @code{-rpath}
+linking an ELF executable with shared objects. All @option{-rpath}
arguments are concatenated and passed to the runtime linker, which uses
-them to locate shared objects at runtime. The @code{-rpath} option is
+them to locate shared objects at runtime. The @option{-rpath} option is
also used when locating shared objects which are needed by shared
objects explicitly included in the link; see the description of the
-@code{-rpath-link} option. If @code{-rpath} is not used when linking an
+@option{-rpath-link} option. If @option{-rpath} is not used when linking an
ELF executable, the contents of the environment variable
@code{LD_RUN_PATH} will be used if it is defined.
-The @code{-rpath} option may also be used on SunOS. By default, on
+The @option{-rpath} option may also be used on SunOS. By default, on
SunOS, the linker will form a runtime search patch out of all the
-@code{-L} options it is given. If a @code{-rpath} option is used, the
-runtime search path will be formed exclusively using the @code{-rpath}
-options, ignoring the @code{-L} options. This can be useful when using
-gcc, which adds many @code{-L} options which may be on NFS mounted
-filesystems.
+@option{-L} options it is given. If a @option{-rpath} option is used, the
+runtime search path will be formed exclusively using the @option{-rpath}
+options, ignoring the @option{-L} options. This can be useful when using
+gcc, which adds many @option{-L} options which may be on NFS mounted
+file systems.
-For compatibility with other ELF linkers, if the @code{-R} option is
+For compatibility with other ELF linkers, if the @option{-R} option is
followed by a directory name, rather than a file name, it is treated as
-the @code{-rpath} option.
+the @option{-rpath} option.
@end ifset
@ifset GENERIC
@cindex link-time runtime library search path
-@kindex -rpath-link
-@item -rpath-link @var{DIR}
+@kindex -rpath-link=@var{dir}
+@item -rpath-link=@var{dir}
When using ELF or SunOS, one shared library may require another. This
happens when an @code{ld -shared} link includes a shared library as one
of the input files.
When the linker encounters such a dependency when doing a non-shared,
non-relocatable link, it will automatically try to locate the required
shared library and include it in the link, if it is not included
-explicitly. In such a case, the @code{-rpath-link} option
+explicitly. In such a case, the @option{-rpath-link} option
specifies the first set of directories to search. The
-@code{-rpath-link} option may specify a sequence of directory names
+@option{-rpath-link} option may specify a sequence of directory names
either by specifying a list of names separated by colons, or by
appearing multiple times.
runtime linker would do.
The linker uses the following search paths to locate required shared
-libraries.
+libraries:
@enumerate
@item
-Any directories specified by @code{-rpath-link} options.
+Any directories specified by @option{-rpath-link} options.
@item
-Any directories specified by @code{-rpath} options. The difference
-between @code{-rpath} and @code{-rpath-link} is that directories
-specified by @code{-rpath} options are included in the executable and
-used at runtime, whereas the @code{-rpath-link} option is only effective
-at link time. It is for the native linker only.
+Any directories specified by @option{-rpath} options. The difference
+between @option{-rpath} and @option{-rpath-link} is that directories
+specified by @option{-rpath} options are included in the executable and
+used at runtime, whereas the @option{-rpath-link} option is only effective
+at link time. Searching @option{-rpath} in this way is only supported
+by native linkers and cross linkers which have been configured with
+the @option{--with-sysroot} option.
@item
-On an ELF system, if the @code{-rpath} and @code{rpath-link} options
-were not used, search the contents of the environment variable
-@code{LD_RUN_PATH}. It is for the native linker only.
+On an ELF system, for native linkers, if the @option{-rpath} and
+@option{-rpath-link} options were not used, search the contents of the
+environment variable @code{LD_RUN_PATH}.
@item
-On SunOS, if the @code{-rpath} option was not used, search any
-directories specified using @code{-L} options.
+On SunOS, if the @option{-rpath} option was not used, search any
+directories specified using @option{-L} options.
@item
-For a native linker, the contents of the environment variable
-@code{LD_LIBRARY_PATH}.
+For a native linker, the search the contents of the environment
+variable @code{LD_LIBRARY_PATH}.
@item
For a native ELF linker, the directories in @code{DT_RUNPATH} or
@code{DT_RPATH} of a shared library are searched for shared
@cindex shared libraries
Create a shared library. This is currently only supported on ELF, XCOFF
and SunOS platforms. On SunOS, the linker will automatically create a
-shared library if the @code{-e} option is not used and there are
+shared library if the @option{-e} option is not used and there are
undefined symbols in the link.
-@item --sort-common
@kindex --sort-common
-This option tells @code{ld} to sort the common symbols by size when it
-places them in the appropriate output sections. First come all the one
-byte symbols, then all the two bytes, then all the four bytes, and then
-everything else. This is to prevent gaps between symbols due to
-alignment constraints.
+@item --sort-common
+@itemx --sort-common=ascending
+@itemx --sort-common=descending
+This option tells @command{ld} to sort the common symbols by alignment in
+ascending or descending order when it places them in the appropriate output
+sections. The symbol alignments considered are sixteen-byte or larger,
+eight-byte, four-byte, two-byte, and one-byte. This is to prevent gaps
+between symbols due to alignment constraints. If no sorting order is
+specified, then descending order is assumed.
+
+@kindex --sort-section=name
+@item --sort-section=name
+This option will apply @code{SORT_BY_NAME} to all wildcard section
+patterns in the linker script.
+
+@kindex --sort-section=alignment
+@item --sort-section=alignment
+This option will apply @code{SORT_BY_ALIGNMENT} to all wildcard section
+patterns in the linker script.
@kindex --split-by-file
-@item --split-by-file [@var{size}]
-Similar to @code{--split-by-reloc} but creates a new output section for
+@item --split-by-file[=@var{size}]
+Similar to @option{--split-by-reloc} but creates a new output section for
each input file when @var{size} is reached. @var{size} defaults to a
size of 1 if not given.
@kindex --split-by-reloc
-@item --split-by-reloc [@var{count}]
+@item --split-by-reloc[=@var{count}]
Tries to creates extra sections in the output file so that no single
output section in the file contains more than @var{count} relocations.
This is useful when generating huge relocatable files for downloading into
Compute and display statistics about the operation of the linker, such
as execution time and memory usage.
+@kindex --sysroot=@var{directory}
+@item --sysroot=@var{directory}
+Use @var{directory} as the location of the sysroot, overriding the
+configure-time default. This option is only supported by linkers
+that were configured using @option{--with-sysroot}.
+
@kindex --traditional-format
@cindex traditional format
@item --traditional-format
-For some targets, the output of @code{ld} is different in some ways from
-the output of some existing linker. This switch requests @code{ld} to
+For some targets, the output of @command{ld} is different in some ways from
+the output of some existing linker. This switch requests @command{ld} to
use the traditional format instead.
@cindex dbx
-For example, on SunOS, @code{ld} combines duplicate entries in the
+For example, on SunOS, @command{ld} combines duplicate entries in the
symbol string table. This can reduce the size of an output file with
full debugging information by over 30 percent. Unfortunately, the SunOS
@code{dbx} program can not read the resulting program (@code{gdb} has no
-trouble). The @samp{--traditional-format} switch tells @code{ld} to not
+trouble). The @samp{--traditional-format} switch tells @command{ld} to not
combine duplicate entries.
-@kindex --section-start @var{sectionname}=@var{org}
-@item --section-start @var{sectionname}=@var{org}
+@kindex --section-start=@var{sectionname}=@var{org}
+@item --section-start=@var{sectionname}=@var{org}
Locate a section in the output file at the absolute
address given by @var{org}. You may use this option as many
times as necessary to locate multiple sections in the command
should be no white space between @var{sectionname}, the equals
sign (``@key{=}''), and @var{org}.
-@kindex -Tbss @var{org}
-@kindex -Tdata @var{org}
-@kindex -Ttext @var{org}
+@kindex -Tbss=@var{org}
+@kindex -Tdata=@var{org}
+@kindex -Ttext=@var{org}
@cindex segment origins, cmd line
-@item -Tbss @var{org}
-@itemx -Tdata @var{org}
-@itemx -Ttext @var{org}
-Use @var{org} as the starting address for---respectively---the
-@code{bss}, @code{data}, or the @code{text} segment of the output file.
-@var{org} must be a single hexadecimal integer;
-for compatibility with other linkers, you may omit the leading
-@samp{0x} usually associated with hexadecimal values.
+@item -Tbss=@var{org}
+@itemx -Tdata=@var{org}
+@itemx -Ttext=@var{org}
+Same as @option{--section-start}, with @code{.bss}, @code{.data} or
+@code{.text} as the @var{sectionname}.
+
+@kindex -Ttext-segment=@var{org}
+@item -Ttext-segment=@var{org}
+@cindex text segment origin, cmd line
+When creating an ELF executable or shared object, it will set the address
+of the first byte of the text segment.
+
+@kindex --unresolved-symbols
+@item --unresolved-symbols=@var{method}
+Determine how to handle unresolved symbols. There are four possible
+values for @samp{method}:
+
+@table @samp
+@item ignore-all
+Do not report any unresolved symbols.
+
+@item report-all
+Report all unresolved symbols. This is the default.
+
+@item ignore-in-object-files
+Report unresolved symbols that are contained in shared libraries, but
+ignore them if they come from regular object files.
+
+@item ignore-in-shared-libs
+Report unresolved symbols that come from regular object files, but
+ignore them if they come from shared libraries. This can be useful
+when creating a dynamic binary and it is known that all the shared
+libraries that it should be referencing are included on the linker's
+command line.
+@end table
+
+The behaviour for shared libraries on their own can also be controlled
+by the @option{--[no-]allow-shlib-undefined} option.
+
+Normally the linker will generate an error message for each reported
+unresolved symbol but the option @option{--warn-unresolved-symbols}
+can change this to a warning.
@kindex --verbose
@cindex verbose
@item --dll-verbose
@itemx --verbose
-Display the version number for @code{ld} and list the linker emulations
+Display the version number for @command{ld} and list the linker emulations
supported. Display which input files can and cannot be opened. Display
-the linker script if using a default builtin script.
+the linker script being used by the linker.
@kindex --version-script=@var{version-scriptfile}
@cindex version script, symbol versions
-@itemx --version-script=@var{version-scriptfile}
+@item --version-script=@var{version-scriptfile}
Specify the name of a version script to the linker. This is typically
used when creating shared libraries to specify additional information
-about the version heirarchy for the library being created. This option
+about the version hierarchy for the library being created. This option
is only meaningful on ELF platforms which support shared libraries.
@xref{VERSION}.
@cindex combining symbols, warnings on
@item --warn-common
Warn when a common symbol is combined with another common symbol or with
-a symbol definition. Unix linkers allow this somewhat sloppy practice,
+a symbol definition. Unix linkers allow this somewhat sloppy practise,
but linkers on some other operating systems do not. This option allows
you to find potential problems from combining global symbols.
-Unfortunately, some C libraries use this practice, so you may get some
+Unfortunately, some C libraries use this practise, so you may get some
warnings about symbols in the libraries as well as in your programs.
There are three kinds of global symbols, illustrated here by C examples:
is, if the @code{SECTIONS} command does not specify a start address for
the section (@pxref{SECTIONS}).
+@kindex --warn-shared-textrel
+@item --warn-shared-textrel
+Warn if the linker adds a DT_TEXTREL to a shared object.
+
+@kindex --warn-unresolved-symbols
+@item --warn-unresolved-symbols
+If the linker is going to report an unresolved symbol (see the option
+@option{--unresolved-symbols}) it will normally generate an error.
+This option makes it generate a warning instead.
+
+@kindex --error-unresolved-symbols
+@item --error-unresolved-symbols
+This restores the linker's default behaviour of generating errors when
+it is reporting unresolved symbols.
+
@kindex --whole-archive
@cindex including an entire archive
@item --whole-archive
For each archive mentioned on the command line after the
-@code{--whole-archive} option, include every object file in the archive
+@option{--whole-archive} option, include every object file in the archive
in the link, rather than searching the archive for the required object
files. This is normally used to turn an archive file into a shared
library, forcing every object to be included in the resulting shared
library. This option may be used more than once.
Two notes when using this option from gcc: First, gcc doesn't know
-about this option, so you have to use @code{-Wl,-whole-archive}.
-Second, don't forget to use @code{-Wl,-no-whole-archive} after your
+about this option, so you have to use @option{-Wl,-whole-archive}.
+Second, don't forget to use @option{-Wl,-no-whole-archive} after your
list of archives, because gcc will add its own list of archives to
your link and you may not want this flag to affect those as well.
-@kindex --wrap
-@item --wrap @var{symbol}
+@kindex --wrap=@var{symbol}
+@item --wrap=@var{symbol}
Use a wrapper function for @var{symbol}. Any undefined reference to
@var{symbol} will be resolved to @code{__wrap_@var{symbol}}. Any
undefined reference to @code{__real_@var{symbol}} will be resolved to
@smallexample
void *
-__wrap_malloc (int c)
+__wrap_malloc (size_t c)
@{
- printf ("malloc called with %ld\n", c);
+ printf ("malloc called with %zu\n", c);
return __real_malloc (c);
@}
@end smallexample
-If you link other code with this file using @code{--wrap malloc}, then
+If you link other code with this file using @option{--wrap malloc}, then
all calls to @code{malloc} will call the function @code{__wrap_malloc}
instead. The call to @code{__real_malloc} in @code{__wrap_malloc} will
call the real @code{malloc} function.
You may wish to provide a @code{__real_malloc} function as well, so that
-links without the @code{--wrap} option will succeed. If you do this,
+links without the @option{--wrap} option will succeed. If you do this,
you should not put the definition of @code{__real_malloc} in the same
file as @code{__wrap_malloc}; if you do, the assembler may resolve the
call before the linker has a chance to wrap it to @code{malloc}.
+@kindex --eh-frame-hdr
+@item --eh-frame-hdr
+Request creation of @code{.eh_frame_hdr} section and ELF
+@code{PT_GNU_EH_FRAME} segment header.
+
@kindex --enable-new-dtags
@kindex --disable-new-dtags
@item --enable-new-dtags
@itemx --disable-new-dtags
This linker can create the new dynamic tags in ELF. But the older ELF
systems may not understand them. If you specify
-@code{--enable-new-dtags}, the dynamic tags will be created as needed.
-If you specify @code{--disable-new-dtags}, no new dynamic tags will be
+@option{--enable-new-dtags}, the dynamic tags will be created as needed.
+If you specify @option{--disable-new-dtags}, no new dynamic tags will be
created. By default, the new dynamic tags are not created. Note that
those options are only available for ELF systems.
+@kindex --hash-size=@var{number}
+@item --hash-size=@var{number}
+Set the default size of the linker's hash tables to a prime number
+close to @var{number}. Increasing this value can reduce the length of
+time it takes the linker to perform its tasks, at the expense of
+increasing the linker's memory requirements. Similarly reducing this
+value can reduce the memory requirements at the expense of speed.
+
+@kindex --hash-style=@var{style}
+@item --hash-style=@var{style}
+Set the type of linker's hash table(s). @var{style} can be either
+@code{sysv} for classic ELF @code{.hash} section, @code{gnu} for
+new style GNU @code{.gnu.hash} section or @code{both} for both
+the classic ELF @code{.hash} and new style GNU @code{.gnu.hash}
+hash tables. The default is @code{sysv}.
+
+@kindex --reduce-memory-overheads
+@item --reduce-memory-overheads
+This option reduces memory requirements at ld runtime, at the expense of
+linking speed. This was introduced to select the old O(n^2) algorithm
+for link map file generation, rather than the new O(n) algorithm which uses
+about 40% more memory for symbol storage.
+
+Another effect of the switch is to set the default hash table size to
+1021, which again saves memory at the cost of lengthening the linker's
+run time. This is not done however if the @option{--hash-size} switch
+has been used.
+
+The @option{--reduce-memory-overheads} switch may be also be used to
+enable other tradeoffs in future versions of the linker.
+
+@kindex --build-id
+@kindex --build-id=@var{style}
+@item --build-id
+@itemx --build-id=@var{style}
+Request creation of @code{.note.gnu.build-id} ELF note section.
+The contents of the note are unique bits identifying this linked
+file. @var{style} can be @code{uuid} to use 128 random bits,
+@code{sha1} to use a 160-bit @sc{SHA1} hash on the normative
+parts of the output contents, @code{md5} to use a 128-bit
+@sc{MD5} hash on the normative parts of the output contents, or
+@code{0x@var{hexstring}} to use a chosen bit string specified as
+an even number of hexadecimal digits (@code{-} and @code{:}
+characters between digit pairs are ignored). If @var{style} is
+omitted, @code{sha1} is used.
+
+The @code{md5} and @code{sha1} styles produces an identifier
+that is always the same in an identical output file, but will be
+unique among all nonidentical output files. It is not intended
+to be compared as a checksum for the file's contents. A linked
+file may be changed later by other tools, but the build ID bit
+string identifying the original linked file does not change.
+
+Passing @code{none} for @var{style} disables the setting from any
+@code{--build-id} options earlier on the command line.
@end table
@c man end
-@subsection Options specific to i386 PE targets
+@subsection Options Specific to i386 PE Targets
@c man begin OPTIONS
-The i386 PE linker supports the @code{-shared} option, which causes
+The i386 PE linker supports the @option{-shared} option, which causes
the output to be a dynamically linked library (DLL) instead of a
normal executable. You should name the output @code{*.dll} when you
use this option. In addition, the linker fully supports the standard
PE target. Options that take values may be separated from their
values by either a space or an equals sign.
-@table @code
+@table @gcctabopt
@kindex --add-stdcall-alias
@item --add-stdcall-alias
If given, symbols with a stdcall suffix (@@@var{nn}) will be exported
as-is and also with the suffix stripped.
+[This option is specific to the i386 PE targeted port of the linker]
@kindex --base-file
@item --base-file @var{file}
Use @var{file} as the name of a file in which to save the base
addresses of all the relocations needed for generating DLLs with
@file{dlltool}.
+[This is an i386 PE specific option]
@kindex --dll
@item --dll
Create a DLL instead of a regular executable. You may also use
-@code{-shared} or specify a @code{LIBRARY} in a given @code{.def}
+@option{-shared} or specify a @code{LIBRARY} in a given @code{.def}
file.
+[This option is specific to the i386 PE targeted port of the linker]
+
+@kindex --enable-long-section-names
+@kindex --disable-long-section-names
+@item --enable-long-section-names
+@itemx --disable-long-section-names
+The PE variants of the Coff object format add an extension that permits
+the use of section names longer than eight characters, the normal limit
+for Coff. By default, these names are only allowed in object files, as
+fully-linked executable images do not carry the Coff string table required
+to support the longer names. As a GNU extension, it is possible to
+allow their use in executable images as well, or to (probably pointlessly!)
+disallow it in object files, by using these two options. Executable images
+generated with these long section names are slightly non-standard, carrying
+as they do a string table, and may generate confusing output when examined
+with non-GNU PE-aware tools, such as file viewers and dumpers. However,
+GDB relies on the use of PE long section names to find Dwarf-2 debug
+information sections in an executable image at runtime, and so if neither
+option is specified on the command-line, @command{ld} will enable long
+section names, overriding the default and technically correct behaviour,
+when it finds the presence of debug information while linking an executable
+image and not stripping symbols.
+[This option is valid for all PE targeted ports of the linker]
@kindex --enable-stdcall-fixup
@kindex --disable-stdcall-fixup
@item --enable-stdcall-fixup
@itemx --disable-stdcall-fixup
If the link finds a symbol that it cannot resolve, it will attempt to
-do "fuzzy linking" by looking for another defined symbol that differs
+do ``fuzzy linking'' by looking for another defined symbol that differs
only in the format of the symbol name (cdecl vs stdcall) and will
resolve that symbol by linking to the match. For example, the
undefined symbol @code{_foo} might be linked to the function
to the function @code{_bar}. When the linker does this, it prints a
warning, since it normally should have failed to link, but sometimes
import libraries generated from third-party dlls may need this feature
-to be usable. If you specify @code{--enable-stdcall-fixup}, this
+to be usable. If you specify @option{--enable-stdcall-fixup}, this
feature is fully enabled and warnings are not printed. If you specify
-@code{--disable-stdcall-fixup}, this feature is disabled and such
+@option{--disable-stdcall-fixup}, this feature is disabled and such
mismatches are considered to be errors.
+[This option is specific to the i386 PE targeted port of the linker]
@cindex DLLs, creating
@kindex --export-all-symbols
explicitly exported via DEF files or implicitly exported via function
attributes, the default is to not export anything else unless this
option is given. Note that the symbols @code{DllMain@@12},
-@code{DllEntryPoint@@0}, @code{DllMainCRTStartup@@12}, and
+@code{DllEntryPoint@@0}, @code{DllMainCRTStartup@@12}, and
@code{impure_ptr} will not be automatically
-exported. Also, symbols imported from other DLLs will not be
-re-exported, nor will symbols specifying the DLL's internal layout
-such as those beginning with @code{_head_} or ending with
-@code{_iname}. In addition, no symbols from @code{libgcc},
+exported. Also, symbols imported from other DLLs will not be
+re-exported, nor will symbols specifying the DLL's internal layout
+such as those beginning with @code{_head_} or ending with
+@code{_iname}. In addition, no symbols from @code{libgcc},
@code{libstd++}, @code{libmingw32}, or @code{crtX.o} will be exported.
Symbols whose names begin with @code{__rtti_} or @code{__builtin_} will
not be exported, to help with C++ DLLs. Finally, there is an
-extensive list of cygwin-private symbols that are not exported
+extensive list of cygwin-private symbols that are not exported
(obviously, this applies on when building DLLs for cygwin targets).
-These cygwin-excludes are: @code{_cygwin_dll_entry@@12},
+These cygwin-excludes are: @code{_cygwin_dll_entry@@12},
@code{_cygwin_crt0_common@@8}, @code{_cygwin_noncygwin_dll_entry@@12},
-@code{_fmode}, @code{_impure_ptr}, @code{cygwin_attach_dll},
+@code{_fmode}, @code{_impure_ptr}, @code{cygwin_attach_dll},
@code{cygwin_premain0}, @code{cygwin_premain1}, @code{cygwin_premain2},
-@code{cygwin_premain3}, and @code{environ}.
+@code{cygwin_premain3}, and @code{environ}.
+[This option is specific to the i386 PE targeted port of the linker]
@kindex --exclude-symbols
@item --exclude-symbols @var{symbol},@var{symbol},...
Specifies a list of symbols which should not be automatically
exported. The symbol names may be delimited by commas or colons.
+[This option is specific to the i386 PE targeted port of the linker]
@kindex --file-alignment
@item --file-alignment
Specify the file alignment. Sections in the file will always begin at
file offsets which are multiples of this number. This defaults to
512.
+[This option is specific to the i386 PE targeted port of the linker]
@cindex heap size
@kindex --heap
@item --heap @var{reserve}
@itemx --heap @var{reserve},@var{commit}
-Specify the amount of memory to reserve (and optionally commit) to be
-used as heap for this program. The default is 1Mb reserved, 4K
+Specify the number of bytes of memory to reserve (and optionally commit)
+to be used as heap for this program. The default is 1Mb reserved, 4K
committed.
+[This option is specific to the i386 PE targeted port of the linker]
@cindex image base
@kindex --image-base
your dlls, each should have a unique base address and not overlap any
other dlls. The default is 0x400000 for executables, and 0x10000000
for dlls.
+[This option is specific to the i386 PE targeted port of the linker]
@kindex --kill-at
@item --kill-at
If given, the stdcall suffixes (@@@var{nn}) will be stripped from
symbols before they are exported.
+[This option is specific to the i386 PE targeted port of the linker]
+
+@kindex --large-address-aware
+@item --large-address-aware
+If given, the appropriate bit in the ``Characteristics'' field of the COFF
+header is set to indicate that this executable supports virtual addresses
+greater than 2 gigabytes. This should be used in conjunction with the /3GB
+or /USERVA=@var{value} megabytes switch in the ``[operating systems]''
+section of the BOOT.INI. Otherwise, this bit has no effect.
+[This option is specific to PE targeted ports of the linker]
@kindex --major-image-version
@item --major-image-version @var{value}
-Sets the major number of the "image version". Defaults to 1.
+Sets the major number of the ``image version''. Defaults to 1.
+[This option is specific to the i386 PE targeted port of the linker]
@kindex --major-os-version
@item --major-os-version @var{value}
-Sets the major number of the "os version". Defaults to 4.
+Sets the major number of the ``os version''. Defaults to 4.
+[This option is specific to the i386 PE targeted port of the linker]
@kindex --major-subsystem-version
@item --major-subsystem-version @var{value}
-Sets the major number of the "subsystem version". Defaults to 4.
+Sets the major number of the ``subsystem version''. Defaults to 4.
+[This option is specific to the i386 PE targeted port of the linker]
@kindex --minor-image-version
@item --minor-image-version @var{value}
-Sets the minor number of the "image version". Defaults to 0.
+Sets the minor number of the ``image version''. Defaults to 0.
+[This option is specific to the i386 PE targeted port of the linker]
@kindex --minor-os-version
@item --minor-os-version @var{value}
-Sets the minor number of the "os version". Defaults to 0.
+Sets the minor number of the ``os version''. Defaults to 0.
+[This option is specific to the i386 PE targeted port of the linker]
@kindex --minor-subsystem-version
@item --minor-subsystem-version @var{value}
-Sets the minor number of the "subsystem version". Defaults to 0.
+Sets the minor number of the ``subsystem version''. Defaults to 0.
+[This option is specific to the i386 PE targeted port of the linker]
@cindex DEF files, creating
@cindex DLLs, creating
(which should be called @code{*.def}) may be used to create an import
library with @code{dlltool} or may be used as a reference to
automatically or implicitly exported symbols.
+[This option is specific to the i386 PE targeted port of the linker]
@cindex DLLs, creating
@kindex --out-implib
The linker will create the file @var{file} which will contain an
import lib corresponding to the DLL the linker is generating. This
import lib (which should be called @code{*.dll.a} or @code{*.a}
-may be used to link clients against the generated DLL; this behavior
+may be used to link clients against the generated DLL; this behaviour
makes it possible to skip a separate @code{dlltool} import library
creation step.
+[This option is specific to the i386 PE targeted port of the linker]
@kindex --enable-auto-image-base
@item --enable-auto-image-base
from the dllname to create unique image bases for each DLL, in-memory
collisions and relocations which can delay program execution are
avoided.
+[This option is specific to the i386 PE targeted port of the linker]
@kindex --disable-auto-image-base
@item --disable-auto-image-base
Do not automatically generate a unique image base. If there is no
user-specified image base (@code{--image-base}) then use the platform
default.
+[This option is specific to the i386 PE targeted port of the linker]
@cindex DLLs, linking to
@kindex --dll-search-prefix
@item --dll-search-prefix @var{string}
-When linking dynamically to a dll without an import library, i
-search for @code{<string><basename>.dll} in preference to
-@code{lib<basename>.dll}. This behavior allows easy distinction
+When linking dynamically to a dll without an import library,
+search for @code{<string><basename>.dll} in preference to
+@code{lib<basename>.dll}. This behaviour allows easy distinction
between DLLs built for the various "subplatforms": native, cygwin,
uwin, pw, etc. For instance, cygwin DLLs typically use
-@code{--dll-search-prefix=cyg}.
+@code{--dll-search-prefix=cyg}.
+[This option is specific to the i386 PE targeted port of the linker]
@kindex --enable-auto-import
@item --enable-auto-import
-Do sophisticalted linking of @code{_symbol} to @code{__imp__symbol} for
-DATA imports from DLLs, and create the necessary thunking symbols when
-building the DLLs with those DATA exports.
+Do sophisticated linking of @code{_symbol} to @code{__imp__symbol} for
+DATA imports from DLLs, and create the necessary thunking symbols when
+building the import libraries with those DATA exports. Note: Use of the
+'auto-import' extension will cause the text section of the image file
+to be made writable. This does not conform to the PE-COFF format
+specification published by Microsoft.
+
+Note - use of the 'auto-import' extension will also cause read only
+data which would normally be placed into the .rdata section to be
+placed into the .data section instead. This is in order to work
+around a problem with consts that is described here:
+http://www.cygwin.com/ml/cygwin/2004-09/msg01101.html
+
+Using 'auto-import' generally will 'just work' -- but sometimes you may
+see this message:
+
+"variable '<var>' can't be auto-imported. Please read the
+documentation for ld's @code{--enable-auto-import} for details."
+
+This message occurs when some (sub)expression accesses an address
+ultimately given by the sum of two constants (Win32 import tables only
+allow one). Instances where this may occur include accesses to member
+fields of struct variables imported from a DLL, as well as using a
+constant index into an array variable imported from a DLL. Any
+multiword variable (arrays, structs, long long, etc) may trigger
+this error condition. However, regardless of the exact data type
+of the offending exported variable, ld will always detect it, issue
+the warning, and exit.
+
+There are several ways to address this difficulty, regardless of the
+data type of the exported variable:
+
+One way is to use --enable-runtime-pseudo-reloc switch. This leaves the task
+of adjusting references in your client code for runtime environment, so
+this method works only when runtime environment supports this feature.
+
+A second solution is to force one of the 'constants' to be a variable --
+that is, unknown and un-optimizable at compile time. For arrays,
+there are two possibilities: a) make the indexee (the array's address)
+a variable, or b) make the 'constant' index a variable. Thus:
+
+@example
+extern type extern_array[];
+extern_array[1] -->
+ @{ volatile type *t=extern_array; t[1] @}
+@end example
+
+or
+
+@example
+extern type extern_array[];
+extern_array[1] -->
+ @{ volatile int t=1; extern_array[t] @}
+@end example
+
+For structs (and most other multiword data types) the only option
+is to make the struct itself (or the long long, or the ...) variable:
+
+@example
+extern struct s extern_struct;
+extern_struct.field -->
+ @{ volatile struct s *t=&extern_struct; t->field @}
+@end example
+
+or
+
+@example
+extern long long extern_ll;
+extern_ll -->
+ @{ volatile long long * local_ll=&extern_ll; *local_ll @}
+@end example
+
+A third method of dealing with this difficulty is to abandon
+'auto-import' for the offending symbol and mark it with
+@code{__declspec(dllimport)}. However, in practise that
+requires using compile-time #defines to indicate whether you are
+building a DLL, building client code that will link to the DLL, or
+merely building/linking to a static library. In making the choice
+between the various methods of resolving the 'direct address with
+constant offset' problem, you should consider typical real-world usage:
+
+Original:
+@example
+--foo.h
+extern int arr[];
+--foo.c
+#include "foo.h"
+void main(int argc, char **argv)@{
+ printf("%d\n",arr[1]);
+@}
+@end example
+
+Solution 1:
+@example
+--foo.h
+extern int arr[];
+--foo.c
+#include "foo.h"
+void main(int argc, char **argv)@{
+ /* This workaround is for win32 and cygwin; do not "optimize" */
+ volatile int *parr = arr;
+ printf("%d\n",parr[1]);
+@}
+@end example
+
+Solution 2:
+@example
+--foo.h
+/* Note: auto-export is assumed (no __declspec(dllexport)) */
+#if (defined(_WIN32) || defined(__CYGWIN__)) && \
+ !(defined(FOO_BUILD_DLL) || defined(FOO_STATIC))
+#define FOO_IMPORT __declspec(dllimport)
+#else
+#define FOO_IMPORT
+#endif
+extern FOO_IMPORT int arr[];
+--foo.c
+#include "foo.h"
+void main(int argc, char **argv)@{
+ printf("%d\n",arr[1]);
+@}
+@end example
+
+A fourth way to avoid this problem is to re-code your
+library to use a functional interface rather than a data interface
+for the offending variables (e.g. set_foo() and get_foo() accessor
+functions).
+[This option is specific to the i386 PE targeted port of the linker]
@kindex --disable-auto-import
@item --disable-auto-import
-Do not attempt to do sophisticalted linking of @code{_symbol} to
+Do not attempt to do sophisticated linking of @code{_symbol} to
@code{__imp__symbol} for DATA imports from DLLs.
+[This option is specific to the i386 PE targeted port of the linker]
+
+@kindex --enable-runtime-pseudo-reloc
+@item --enable-runtime-pseudo-reloc
+If your code contains expressions described in --enable-auto-import section,
+that is, DATA imports from DLL with non-zero offset, this switch will create
+a vector of 'runtime pseudo relocations' which can be used by runtime
+environment to adjust references to such data in your client code.
+[This option is specific to the i386 PE targeted port of the linker]
+
+@kindex --disable-runtime-pseudo-reloc
+@item --disable-runtime-pseudo-reloc
+Do not create pseudo relocations for non-zero offset DATA imports from
+DLLs. This is the default.
+[This option is specific to the i386 PE targeted port of the linker]
@kindex --enable-extra-pe-debug
@item --enable-extra-pe-debug
Show additional debug info related to auto-import symbol thunking.
+[This option is specific to the i386 PE targeted port of the linker]
@kindex --section-alignment
@item --section-alignment
Sets the section alignment. Sections in memory will always begin at
addresses which are a multiple of this number. Defaults to 0x1000.
+[This option is specific to the i386 PE targeted port of the linker]
@cindex stack size
@kindex --stack
@item --stack @var{reserve}
@itemx --stack @var{reserve},@var{commit}
-Specify the amount of memory to reserve (and optionally commit) to be
-used as stack for this program. The default is 32Mb reserved, 4K
+Specify the number of bytes of memory to reserve (and optionally commit)
+to be used as stack for this program. The default is 2Mb reserved, 4K
committed.
+[This option is specific to the i386 PE targeted port of the linker]
@kindex --subsystem
@item --subsystem @var{which}
@itemx --subsystem @var{which}:@var{major}.@var{minor}
Specifies the subsystem under which your program will execute. The
legal values for @var{which} are @code{native}, @code{windows},
-@code{console}, and @code{posix}. You may optionally set the
-subsystem version also.
+@code{console}, @code{posix}, and @code{xbox}. You may optionally set
+the subsystem version also. Numeric values are also accepted for
+@var{which}.
+[This option is specific to the i386 PE targeted port of the linker]
+
+The following options set flags in the @code{DllCharacteristics} field
+of the PE file header:
+[These options are specific to PE targeted ports of the linker]
+
+@kindex --dynamicbase
+@item --dynamicbase
+The image base address may be relocated using address space layout
+randomization (ASLR). This feature was introduced with MS Windows
+Vista for i386 PE targets.
+
+@kindex --forceinteg
+@item --forceinteg
+Code integrity checks are enforced.
+
+@kindex --nxcompat
+@item --nxcompat
+The image is compatible with the Data Execution Prevention.
+This feature was introduced with MS Windows XP SP2 for i386 PE targets.
+
+@kindex --no-isolation
+@item --no-isolation
+Although the image understands isolation, do not isolate the image.
+
+@kindex --no-seh
+@item --no-seh
+The image does not use SEH. No SE handler may be called from
+this image.
+
+@kindex --no-bind
+@item --no-bind
+Do not bind this image.
+
+@kindex --wdmdriver
+@item --wdmdriver
+The driver uses the MS Windows Driver Model.
+
+@kindex --tsaware
+@item --tsaware
+The image is Terminal Server aware.
+
+@end table
+
+@c man end
+
+@ifset M68HC11
+@subsection Options specific to Motorola 68HC11 and 68HC12 targets
+
+@c man begin OPTIONS
+
+The 68HC11 and 68HC12 linkers support specific options to control the
+memory bank switching mapping and trampoline code generation.
+
+@table @gcctabopt
+
+@kindex --no-trampoline
+@item --no-trampoline
+This option disables the generation of trampoline. By default a trampoline
+is generated for each far function which is called using a @code{jsr}
+instruction (this happens when a pointer to a far function is taken).
+
+@kindex --bank-window
+@item --bank-window @var{name}
+This option indicates to the linker the name of the memory region in
+the @samp{MEMORY} specification that describes the memory bank window.
+The definition of such region is then used by the linker to compute
+paging and addresses within the memory window.
+
+@end table
+
+@c man end
+@end ifset
+
+@ifset M68K
+@subsection Options specific to Motorola 68K target
+
+@c man begin OPTIONS
+
+The following options are supported to control handling of GOT generation
+when linking for 68K targets.
+
+@table @gcctabopt
+
+@kindex --got
+@item --got=@var{type}
+This option tells the linker which GOT generation scheme to use.
+@var{type} should be one of @samp{single}, @samp{negative},
+@samp{multigot} or @samp{target}. For more information refer to the
+Info entry for @file{ld}.
@end table
@c man end
+@end ifset
@ifset UsesEnvVars
@node Environment
@c man begin ENVIRONMENT
-You can change the behavior of @code{ld} with the environment variables
-@code{GNUTARGET}, @code{LDEMULATION}, and @code{COLLECT_NO_DEMANGLE}.
+You can change the behaviour of @command{ld} with the environment variables
+@ifclear SingleFormat
+@code{GNUTARGET},
+@end ifclear
+@code{LDEMULATION} and @code{COLLECT_NO_DEMANGLE}.
+@ifclear SingleFormat
@kindex GNUTARGET
@cindex default input format
@code{GNUTARGET} determines the input-file object format if you don't
use @samp{-b} (or its synonym @samp{--format}). Its value should be one
of the BFD names for an input format (@pxref{BFD}). If there is no
-@code{GNUTARGET} in the environment, @code{ld} uses the natural format
+@code{GNUTARGET} in the environment, @command{ld} uses the natural format
of the target. If @code{GNUTARGET} is set to @code{default} then BFD
attempts to discover the input format by examining binary input files;
this method often succeeds, but there are potential ambiguities, since
object-file formats is unique. However, the configuration procedure for
BFD on each system places the conventional format for that system first
in the search-list, so ambiguities are resolved in favor of convention.
+@end ifclear
@kindex LDEMULATION
@cindex default emulation
output section, the value of the location counter will be
@samp{0x8000000} plus the size of the @samp{.data} output section. The
effect is that the linker will place the @samp{.bss} output section
-immediately after the @samp{.data} output section in memory
+immediately after the @samp{.data} output section in memory.
The linker will ensure that each output section has the required
alignment, by increasing the location counter if necessary. In this
* Format Commands:: Commands dealing with object file formats
@end ifclear
+* REGION_ALIAS:: Assign alias names to memory regions
* Miscellaneous Commands:: Other linker script commands
@end menu
@node Entry Point
-@subsection Setting the entry point
+@subsection Setting the Entry Point
@kindex ENTRY(@var{symbol})
@cindex start of execution
@cindex first instruction
@end itemize
@node File Commands
-@subsection Commands dealing with files
+@subsection Commands Dealing with Files
@cindex linker script file commands
Several linker script commands deal with files.
@cindex including a linker script
Include the linker script @var{filename} at this point. The file will
be searched for in the current directory, and in any directory specified
-with the @code{-L} option. You can nest calls to @code{INCLUDE} up to
+with the @option{-L} option. You can nest calls to @code{INCLUDE} up to
10 levels deep.
+You can place @code{INCLUDE} directives at the top level, in @code{MEMORY} or
+@code{SECTIONS} commands, or in output section descriptions.
+
@item INPUT(@var{file}, @var{file}, @dots{})
@itemx INPUT(@var{file} @var{file} @dots{})
@kindex INPUT(@var{files})
In fact, if you like, you can list all of your input files in the linker
script, and then invoke the linker with nothing but a @samp{-T} option.
-The linker will first try to open the file in the current directory. If
-it is not found, the linker will search through the archive library
-search path. See the description of @samp{-L} in @ref{Options,,Command
-Line Options}.
+In case a @dfn{sysroot prefix} is configured, and the filename starts
+with the @samp{/} character, and the script being processed was
+located inside the @dfn{sysroot prefix}, the filename will be looked
+for in the @dfn{sysroot prefix}. Otherwise, the linker will try to
+open the file in the current directory. If it is not found, the
+linker will search through the archive library search path. See the
+description of @samp{-L} in @ref{Options,,Command Line Options}.
-If you use @samp{INPUT (-l@var{file})}, @code{ld} will transform the
+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
@samp{-l}.
new undefined references are created. See the description of @samp{-(}
in @ref{Options,,Command Line Options}.
+@item AS_NEEDED(@var{file}, @var{file}, @dots{})
+@itemx AS_NEEDED(@var{file} @var{file} @dots{})
+@kindex AS_NEEDED(@var{files})
+This construct can appear only inside of the @code{INPUT} or @code{GROUP}
+commands, among other filenames. The files listed will be handled
+as if they appear directly in the @code{INPUT} or @code{GROUP} commands,
+with the exception of ELF shared libraries, that will be added only
+when they are actually needed. This construct essentially enables
+@option{--as-needed} option for all the files listed inside of it
+and restores previous @option{--as-needed} resp. @option{--no-as-needed}
+setting afterwards.
+
@item OUTPUT(@var{filename})
@kindex OUTPUT(@var{filename})
-@cindex output file name in linker scripot
+@cindex output file name in linker script
The @code{OUTPUT} command names the output file. Using
@code{OUTPUT(@var{filename})} in the linker script is exactly like using
@samp{-o @var{filename}} on the command line (@pxref{Options,,Command
@cindex archive search path in linker script
@cindex search path in linker script
The @code{SEARCH_DIR} command adds @var{path} to the list of paths where
-@code{ld} looks for archive libraries. Using
+@command{ld} looks for archive libraries. Using
@code{SEARCH_DIR(@var{path})} is exactly like using @samp{-L @var{path}}
on the command line (@pxref{Options,,Command Line Options}). If both
are used, then the linker will search both paths. Paths specified using
@ifclear SingleFormat
@node Format Commands
-@subsection Commands dealing with object file formats
+@subsection Commands Dealing with Object File Formats
A couple of linker script commands deal with object file formats.
@table @code
@cindex output file format in linker script
The @code{OUTPUT_FORMAT} command names the BFD format to use for the
output file (@pxref{BFD}). Using @code{OUTPUT_FORMAT(@var{bfdname})} is
-exactly like using @samp{-oformat @var{bfdname}} on the command line
+exactly like using @samp{--oformat @var{bfdname}} on the command line
(@pxref{Options,,Command Line Options}). If both are used, the command
line option takes precedence.
@end table
@end ifclear
+@node REGION_ALIAS
+@subsection Assign alias names to memory regions
+@kindex REGION_ALIAS(@var{alias}, @var{region})
+@cindex region alias
+@cindex region names
+
+Alias names can be added to existing memory regions created with the
+@ref{MEMORY} command. Each name corresponds to at most one memory region.
+
+@smallexample
+REGION_ALIAS(@var{alias}, @var{region})
+@end smallexample
+
+The @code{REGION_ALIAS} function creates an alias name @var{alias} for the
+memory region @var{region}. This allows a flexible mapping of output sections
+to memory regions. An example follows.
+
+Suppose we have an application for embedded systems which come with various
+memory storage devices. All have a general purpose, volatile memory @code{RAM}
+that allows code execution or data storage. Some may have a read-only,
+non-volatile memory @code{ROM} that allows code execution and read-only data
+access. The last variant is a read-only, non-volatile memory @code{ROM2} with
+read-only data access and no code execution capability. We have four output
+sections:
+
+@itemize @bullet
+@item
+@code{.text} program code;
+@item
+@code{.rodata} read-only data;
+@item
+@code{.data} read-write initialized data;
+@item
+@code{.bss} read-write zero initialized data.
+@end itemize
+
+The goal is to provide a linker command file that contains a system independent
+part defining the output sections and a system dependent part mapping the
+output sections to the memory regions available on the system. Our embedded
+systems come with three different memory setups @code{A}, @code{B} and
+@code{C}:
+@multitable @columnfractions .25 .25 .25 .25
+@item Section @tab Variant A @tab Variant B @tab Variant C
+@item .text @tab RAM @tab ROM @tab ROM
+@item .rodata @tab RAM @tab ROM @tab ROM2
+@item .data @tab RAM @tab RAM/ROM @tab RAM/ROM2
+@item .bss @tab RAM @tab RAM @tab RAM
+@end multitable
+The notation @code{RAM/ROM} or @code{RAM/ROM2} means that this section is
+loaded into region @code{ROM} or @code{ROM2} respectively. Please note that
+the load address of the @code{.data} section starts in all three variants at
+the end of the @code{.rodata} section.
+
+The base linker script that deals with the output sections follows. It
+includes the system dependent @code{linkcmds.memory} file that describes the
+memory layout:
+@smallexample
+INCLUDE linkcmds.memory
+
+SECTIONS
+ @{
+ .text :
+ @{
+ *(.text)
+ @} > REGION_TEXT
+ .rodata :
+ @{
+ *(.rodata)
+ rodata_end = .;
+ @} > REGION_RODATA
+ .data : AT (rodata_end)
+ @{
+ data_start = .;
+ *(.data)
+ @} > REGION_DATA
+ data_size = SIZEOF(.data);
+ data_load_start = LOADADDR(.data);
+ .bss :
+ @{
+ *(.bss)
+ @} > REGION_BSS
+ @}
+@end smallexample
+
+Now we need three different @code{linkcmds.memory} files to define memory
+regions and alias names. The content of @code{linkcmds.memory} for the three
+variants @code{A}, @code{B} and @code{C}:
+@table @code
+@item A
+Here everything goes into the @code{RAM}.
+@smallexample
+MEMORY
+ @{
+ RAM : ORIGIN = 0, LENGTH = 4M
+ @}
+
+REGION_ALIAS("REGION_TEXT", RAM);
+REGION_ALIAS("REGION_RODATA", RAM);
+REGION_ALIAS("REGION_DATA", RAM);
+REGION_ALIAS("REGION_BSS", RAM);
+@end smallexample
+@item B
+Program code and read-only data go into the @code{ROM}. Read-write data goes
+into the @code{RAM}. An image of the initialized data is loaded into the
+@code{ROM} and will be copied during system start into the @code{RAM}.
+@smallexample
+MEMORY
+ @{
+ ROM : ORIGIN = 0, LENGTH = 3M
+ RAM : ORIGIN = 0x10000000, LENGTH = 1M
+ @}
+
+REGION_ALIAS("REGION_TEXT", ROM);
+REGION_ALIAS("REGION_RODATA", ROM);
+REGION_ALIAS("REGION_DATA", RAM);
+REGION_ALIAS("REGION_BSS", RAM);
+@end smallexample
+@item C
+Program code goes into the @code{ROM}. Read-only data goes into the
+@code{ROM2}. Read-write data goes into the @code{RAM}. An image of the
+initialized data is loaded into the @code{ROM2} and will be copied during
+system start into the @code{RAM}.
+@smallexample
+MEMORY
+ @{
+ ROM : ORIGIN = 0, LENGTH = 2M
+ ROM2 : ORIGIN = 0x10000000, LENGTH = 1M
+ RAM : ORIGIN = 0x20000000, LENGTH = 1M
+ @}
+
+REGION_ALIAS("REGION_TEXT", ROM);
+REGION_ALIAS("REGION_RODATA", ROM2);
+REGION_ALIAS("REGION_DATA", RAM);
+REGION_ALIAS("REGION_BSS", RAM);
+@end smallexample
+@end table
+
+It is possible to write a common system initialization routine to copy the
+@code{.data} section from @code{ROM} or @code{ROM2} into the @code{RAM} if
+necessary:
+@smallexample
+#include <string.h>
+
+extern char data_start [];
+extern char data_size [];
+extern char data_load_start [];
+
+void copy_data(void)
+@{
+ if (data_start != data_load_start)
+ @{
+ memcpy(data_start, data_load_start, (size_t) data_size);
+ @}
+@}
+@end smallexample
+
@node Miscellaneous Commands
-@subsection Other linker script commands
+@subsection Other Linker Script Commands
There are a few other linker scripts commands.
@table @code
@kindex FORCE_COMMON_ALLOCATION
@cindex common allocation in linker script
This command has the same effect as the @samp{-d} command-line option:
-to make @code{ld} assign space to common symbols even if a relocatable
+to make @command{ld} assign space to common symbols even if a relocatable
output file is specified (@samp{-r}).
-@item NOCROSSREFS(@var{section} @var{section} @dots{})
-@kindex NOCROSSREFS(@var{sections})
-@cindex cross references
-This command may be used to tell @code{ld} to issue an error about any
-references among certain output sections.
+@item INHIBIT_COMMON_ALLOCATION
+@kindex INHIBIT_COMMON_ALLOCATION
+@cindex common allocation in linker script
+This command has the same effect as the @samp{--no-define-common}
+command-line option: to make @code{ld} omit the assignment of addresses
+to common symbols even for a non-relocatable output file.
+
+@item INSERT [ AFTER | BEFORE ] @var{output_section}
+@kindex INSERT
+@cindex insert user script into default script
+This command is typically used in a script specified by @samp{-T} to
+augment the default @code{SECTIONS} with, for example, overlays. It
+inserts all prior linker script statements after (or before)
+@var{output_section}, and also causes @samp{-T} to not override the
+default linker script. The exact insertion point is as for orphan
+sections. @xref{Location Counter}. The insertion happens after the
+linker has mapped input sections to output sections. Prior to the
+insertion, since @samp{-T} scripts are parsed before the default
+linker script, statements in the @samp{-T} script occur before the
+default linker script statements in the internal linker representation
+of the script. In particular, input section assignments will be made
+to @samp{-T} output sections before those in the default script. Here
+is an example of how a @samp{-T} script using @code{INSERT} might look:
-In certain types of programs, particularly on embedded systems when
-using overlays, when one section is loaded into memory, another section
-will not be. Any direct references between the two sections would be
+@smallexample
+SECTIONS
+@{
+ OVERLAY :
+ @{
+ .ov1 @{ ov1*(.text) @}
+ .ov2 @{ ov2*(.text) @}
+ @}
+@}
+INSERT AFTER .text;
+@end smallexample
+
+@item NOCROSSREFS(@var{section} @var{section} @dots{})
+@kindex NOCROSSREFS(@var{sections})
+@cindex cross references
+This command may be used to tell @command{ld} to issue an error about any
+references among certain output sections.
+
+In certain types of programs, particularly on embedded systems when
+using overlays, when one section is loaded into memory, another section
+will not be. Any direct references between the two sections would be
errors. For example, it would be an error if code in one section called
a function defined in the other section.
The @code{NOCROSSREFS} command takes a list of output section names. If
-@code{ld} detects any cross references between the sections, it reports
+@command{ld} detects any cross references between the sections, it reports
an error and returns a non-zero exit status. Note that the
@code{NOCROSSREFS} command uses output section names, not input section
names.
@cindex symbol definition, scripts
@cindex variables, defining
You may assign a value to a symbol in a linker script. This will define
-the symbol as a global symbol.
+the symbol and place it into the symbol table with a global scope.
@menu
* Simple Assignments:: Simple Assignments
* PROVIDE:: PROVIDE
+* PROVIDE_HIDDEN:: PROVIDE_HIDDEN
+* Source Code Reference:: How to use a linker script defined symbol in source code
@end menu
@node Simple Assignments
defined, and the value will be adjusted accordingly.
The special symbol name @samp{.} indicates the location counter. You
-may only use this within a @code{SECTIONS} command.
+may only use this within a @code{SECTIONS} command. @xref{Location Counter}.
The semicolon after @var{expression} is required.
If the program references @samp{etext} but does not define it, the
linker will use the definition in the linker script.
+@node PROVIDE_HIDDEN
+@subsection PROVIDE_HIDDEN
+@cindex PROVIDE_HIDDEN
+Similar to @code{PROVIDE}. For ELF targeted ports, the symbol will be
+hidden and won't be exported.
+
+@node Source Code Reference
+@subsection Source Code Reference
+
+Accessing a linker script defined variable from source code is not
+intuitive. In particular a linker script symbol is not equivalent to
+a variable declaration in a high level language, it is instead a
+symbol that does not have a value.
+
+Before going further, it is important to note that compilers often
+transform names in the source code into different names when they are
+stored in the symbol table. For example, Fortran compilers commonly
+prepend or append an underscore, and C++ performs extensive @samp{name
+mangling}. Therefore there might be a discrepancy between the name
+of a variable as it is used in source code and the name of the same
+variable as it is defined in a linker script. For example in C a
+linker script variable might be referred to as:
+
+@smallexample
+ extern int foo;
+@end smallexample
+
+But in the linker script it might be defined as:
+
+@smallexample
+ _foo = 1000;
+@end smallexample
+
+In the remaining examples however it is assumed that no name
+transformation has taken place.
+
+When a symbol is declared in a high level language such as C, two
+things happen. The first is that the compiler reserves enough space
+in the program's memory to hold the @emph{value} of the symbol. The
+second is that the compiler creates an entry in the program's symbol
+table which holds the symbol's @emph{address}. ie the symbol table
+contains the address of the block of memory holding the symbol's
+value. So for example the following C declaration, at file scope:
+
+@smallexample
+ int foo = 1000;
+@end smallexample
+
+creates a entry called @samp{foo} in the symbol table. This entry
+holds the address of an @samp{int} sized block of memory where the
+number 1000 is initially stored.
+
+When a program references a symbol the compiler generates code that
+first accesses the symbol table to find the address of the symbol's
+memory block and then code to read the value from that memory block.
+So:
+
+@smallexample
+ foo = 1;
+@end smallexample
+
+looks up the symbol @samp{foo} in the symbol table, gets the address
+associated with this symbol and then writes the value 1 into that
+address. Whereas:
+
+@smallexample
+ int * a = & foo;
+@end smallexample
+
+looks up the symbol @samp{foo} in the symbol table, gets it address
+and then copies this address into the block of memory associated with
+the variable @samp{a}.
+
+Linker scripts symbol declarations, by contrast, create an entry in
+the symbol table but do not assign any memory to them. Thus they are
+an address without a value. So for example the linker script definition:
+
+@smallexample
+ foo = 1000;
+@end smallexample
+
+creates an entry in the symbol table called @samp{foo} which holds
+the address of memory location 1000, but nothing special is stored at
+address 1000. This means that you cannot access the @emph{value} of a
+linker script defined symbol - it has no value - all you can do is
+access the @emph{address} of a linker script defined symbol.
+
+Hence when you are using a linker script defined symbol in source code
+you should always take the address of the symbol, and never attempt to
+use its value. For example suppose you want to copy the contents of a
+section of memory called .ROM into a section called .FLASH and the
+linker script contains these declarations:
+
+@smallexample
+@group
+ start_of_ROM = .ROM;
+ end_of_ROM = .ROM + sizeof (.ROM) - 1;
+ start_of_FLASH = .FLASH;
+@end group
+@end smallexample
+
+Then the C source code to perform the copy would be:
+
+@smallexample
+@group
+ extern char start_of_ROM, end_of_ROM, start_of_FLASH;
+
+ memcpy (& start_of_FLASH, & start_of_ROM, & end_of_ROM - & start_of_ROM);
+@end group
+@end smallexample
+
+Note the use of the @samp{&} operators. These are correct.
+
@node SECTIONS
-@section SECTIONS command
+@section SECTIONS Command
@kindex SECTIONS
The @code{SECTIONS} command tells the linker how to map input sections
into output sections, and how to place the output sections in memory.
@end menu
@node Output Section Description
-@subsection Output section description
+@subsection Output Section Description
The full description of an output section looks like this:
@smallexample
@group
-@var{section} [@var{address}] [(@var{type})] : [AT(@var{lma})]
+@var{section} [@var{address}] [(@var{type})] :
+ [AT(@var{lma})] [ALIGN(@var{section_align})] [SUBALIGN(@var{subsection_align})]
@{
@var{output-section-command}
@var{output-section-command}
@end itemize
@node Output Section Name
-@subsection Output section name
+@subsection Output Section Name
@cindex name, section
@cindex section name
The name of the output section is @var{section}. @var{section} must
Discarding}.
@node Output Section Address
-@subsection Output section address
+@subsection Output Section Address
@cindex address, section
@cindex section address
The @var{address} is an expression for the VMA (the virtual memory
location counter.
@node Input Section
-@subsection Input section description
+@subsection Input Section Description
@cindex input sections
@cindex mapping input sections to output sections
The most common output section command is an input section description.
@end menu
@node Input Section Basics
-@subsubsection Input section basics
+@subsubsection Input Section Basics
@cindex input section basics
An input section description consists of a file name optionally followed
by a list of section names in parentheses.
match all files except the ones specified in the EXCLUDE_FILE list. For
example:
@smallexample
-(*(EXCLUDE_FILE (*crtend.o *otherfile.o) .ctors))
+*(EXCLUDE_FILE (*crtend.o *otherfile.o) .ctors)
@end smallexample
will cause all .ctors sections from all files except @file{crtend.o} and
@file{otherfile.o} to be included.
@noindent
The difference between these is the order in which the @samp{.text} and
@samp{.rdata} input sections will appear in the output section. In the
-first example, they will be intermingled. In the second example, all
+first example, they will be intermingled, appearing in the same order as
+they are found in the linker input. In the second example, all
@samp{.text} input sections will appear first, followed by all
@samp{.rdata} input sections.
data.o(.data)
@end smallexample
+You can also specify files within archives by writing a pattern
+matching the archive, a colon, then the pattern matching the file,
+with no whitespace around the colon.
+
+@table @samp
+@item archive:file
+matches file within archive
+@item archive:
+matches the whole archive
+@item :file
+matches file but not one in an archive
+@end table
+
+Either one or both of @samp{archive} and @samp{file} can contain shell
+wildcards. On DOS based file systems, the linker will assume that a
+single letter followed by a colon is a drive specifier, so
+@samp{c:myfile.o} is a simple file specification, not @samp{myfile.o}
+within an archive called @samp{c}. @samp{archive:file} filespecs may
+also be used within an @code{EXCLUDE_FILE} list, but may not appear in
+other linker script contexts. For instance, you cannot extract a file
+from an archive by using @samp{archive:file} in an @code{INPUT}
+command.
+
If you use a file name without a list of sections, then all sections in
the input file will be included in the output section. This is not
commonly done, but it may by useful on occasion. For example:
data.o
@end smallexample
-When you use a file name which does not contain any wild card
+When you use a file name which is not an @samp{archive:file} specifier
+and does not contain any wild card
characters, the linker will first see if you also specified the file
name on the linker command line or in an @code{INPUT} command. If you
did not, the linker will attempt to open the file as an input file, as
the archive search path.
@node Input Section Wildcards
-@subsubsection Input section wildcard patterns
+@subsubsection Input Section Wildcard Patterns
@cindex input section wildcards
@cindex wildcard file name patterns
@cindex file name wildcard patterns
.data1 : @{ data.o(.data) @}
@end smallexample
-@cindex SORT
+@cindex SORT_BY_NAME
Normally, the linker will place files and sections matched by wildcards
in the order in which they are seen during the link. You can change
-this by using the @code{SORT} keyword, which appears before a wildcard
-pattern in parentheses (e.g., @code{SORT(.text*)}). When the
-@code{SORT} keyword is used, the linker will sort the files or sections
+this by using the @code{SORT_BY_NAME} keyword, which appears before a wildcard
+pattern in parentheses (e.g., @code{SORT_BY_NAME(.text*)}). When the
+@code{SORT_BY_NAME} keyword is used, the linker will sort the files or sections
into ascending order by name before placing them in the output file.
+@cindex SORT_BY_ALIGNMENT
+@code{SORT_BY_ALIGNMENT} is very similar to @code{SORT_BY_NAME}. The
+difference is @code{SORT_BY_ALIGNMENT} will sort sections into
+ascending order by alignment before placing them in the output file.
+
+@cindex SORT
+@code{SORT} is an alias for @code{SORT_BY_NAME}.
+
+When there are nested section sorting commands in linker script, there
+can be at most 1 level of nesting for section sorting commands.
+
+@enumerate
+@item
+@code{SORT_BY_NAME} (@code{SORT_BY_ALIGNMENT} (wildcard section pattern)).
+It will sort the input sections by name first, then by alignment if 2
+sections have the same name.
+@item
+@code{SORT_BY_ALIGNMENT} (@code{SORT_BY_NAME} (wildcard section pattern)).
+It will sort the input sections by alignment first, then by name if 2
+sections have the same alignment.
+@item
+@code{SORT_BY_NAME} (@code{SORT_BY_NAME} (wildcard section pattern)) is
+treated the same as @code{SORT_BY_NAME} (wildcard section pattern).
+@item
+@code{SORT_BY_ALIGNMENT} (@code{SORT_BY_ALIGNMENT} (wildcard section pattern))
+is treated the same as @code{SORT_BY_ALIGNMENT} (wildcard section pattern).
+@item
+All other nested section sorting commands are invalid.
+@end enumerate
+
+When both command line section sorting option and linker script
+section sorting command are used, section sorting command always
+takes precedence over the command line option.
+
+If the section sorting command in linker script isn't nested, the
+command line option will make the section sorting command to be
+treated as nested sorting command.
+
+@enumerate
+@item
+@code{SORT_BY_NAME} (wildcard section pattern ) with
+@option{--sort-sections alignment} is equivalent to
+@code{SORT_BY_NAME} (@code{SORT_BY_ALIGNMENT} (wildcard section pattern)).
+@item
+@code{SORT_BY_ALIGNMENT} (wildcard section pattern) with
+@option{--sort-section name} is equivalent to
+@code{SORT_BY_ALIGNMENT} (@code{SORT_BY_NAME} (wildcard section pattern)).
+@end enumerate
+
+If the section sorting command in linker script is nested, the
+command line option will be ignored.
+
If you ever get confused about where input sections are going, use the
@samp{-M} linker option to generate a map file. The map file shows
precisely how input sections are mapped to output sections.
@end smallexample
@node Input Section Common
-@subsubsection Input section for common symbols
+@subsubsection Input Section for Common Symbols
@cindex common symbol placement
@cindex uninitialized data placement
A special notation is needed for common symbols, because in many object
@samp{*(COMMON)}.
@node Input Section Keep
-@subsubsection Input section and garbage collection
+@subsubsection Input Section and Garbage Collection
@cindex KEEP
@cindex garbage collection
When link-time garbage collection is in use (@samp{--gc-sections}),
it is often useful to mark sections that should not be eliminated.
This is accomplished by surrounding an input section's wildcard entry
with @code{KEEP()}, as in @code{KEEP(*(.init))} or
-@code{KEEP(SORT(*)(.ctors))}.
+@code{KEEP(SORT_BY_NAME(*)(.ctors))}.
@node Input Section Example
-@subsubsection Input section example
+@subsubsection Input Section Example
The following example is a complete linker script. It tells the linker
to read all of the sections from file @file{all.o} and place them at the
start of output section @samp{outputa} which starts at location
all.o
foo.o (.input1)
@}
+@end group
+@group
outputb :
@{
foo.o (.input2)
foo1.o (.input1)
@}
+@end group
+@group
outputc :
@{
*(.input1)
@end smallexample
@node Output Section Data
-@subsection Output section data
+@subsection Output Section Data
@cindex data
@cindex section data
@cindex output section data
true of, for example, S-records, the value will be stored in the
endianness of the first input object file.
-Note - these commands only work inside a section description and not
+Note---these commands only work inside a section description and not
between them, so the following will produce an error from the linker:
@smallexample
SECTIONS @{@ .text : @{@ *(.text) @}@ LONG(1) .data : @{@ *(.data) @}@ @}@
current section. It is followed by an expression in parentheses. Any
otherwise unspecified regions of memory within the section (for example,
gaps left due to the required alignment of input sections) are filled
-with the two least significant bytes of the expression, repeated as
+with the value of the expression, repeated as
necessary. A @code{FILL} statement covers memory locations after the
point at which it occurs in the section definition; by including more
than one @code{FILL} statement, you can have different fill patterns in
different parts of an output section.
This example shows how to fill unspecified regions of memory with the
-value @samp{0x9090}:
+value @samp{0x90}:
@smallexample
-FILL(0x9090)
+FILL(0x90909090)
@end smallexample
The @code{FILL} command is similar to the @samp{=@var{fillexp}} output
-section attribute (@pxref{Output Section Fill}), but it only affects the
+section attribute, but it only affects the
part of the section following the @code{FILL} command, rather than the
entire section. If both are used, the @code{FILL} command takes
-precedence.
+precedence. @xref{Output Section Fill}, for details on the fill
+expression.
@node Output Section Keywords
-@subsection Output section keywords
+@subsection Output Section Keywords
There are a couple of keywords which can appear as output section
commands.
ignored for other object file formats.
The symbol @w{@code{__CTOR_LIST__}} marks the start of the global
-constructors, and the symbol @w{@code{__DTOR_LIST}} marks the end. The
+constructors, and the symbol @w{@code{__CTOR_END__}} marks the end.
+Similarly, @w{@code{__DTOR_LIST__}} and @w{@code{__DTOR_END__}} mark
+the start and end of the global destructors. The
first word in the list is the number of entries, followed by the address
of each constructor or destructor, followed by a zero word. The
compiler must arrange to actually run the code. For these object file
which provides some control over the order in which global constructors
are run, you must sort the constructors at link time to ensure that they
are executed in the correct order. When using the @code{CONSTRUCTORS}
-command, use @samp{SORT(CONSTRUCTORS)} instead. When using the
-@code{.ctors} and @code{.dtors} sections, use @samp{*(SORT(.ctors))} and
-@samp{*(SORT(.dtors))} instead of just @samp{*(.ctors)} and
+command, use @samp{SORT_BY_NAME(CONSTRUCTORS)} instead. When using the
+@code{.ctors} and @code{.dtors} sections, use @samp{*(SORT_BY_NAME(.ctors))} and
+@samp{*(SORT_BY_NAME(.dtors))} instead of just @samp{*(.ctors)} and
@samp{*(.dtors)}.
Normally the compiler and linker will handle these issues automatically,
@end table
@node Output Section Discarding
-@subsection Output section discarding
+@subsection Output Section Discarding
@cindex discarding sections
@cindex sections, discarding
@cindex removing sections
-The linker will not create output section which do not have any
-contents. This is for convenience when referring to input sections that
-may or may not be present in any of the input files. For example:
+The linker will not create output sections with no contents. This is
+for convenience when referring to input sections that may or may not
+be present in any of the input files. For example:
@smallexample
-.foo @{ *(.foo) @}
+.foo : @{ *(.foo) @}
@end smallexample
@noindent
will only create a @samp{.foo} section in the output file if there is a
-@samp{.foo} section in at least one input file.
+@samp{.foo} section in at least one input file, and if the input
+sections are not all empty. Other link script directives that allocate
+space in an output section will also create the output section.
-If you use anything other than an input section description as an output
-section command, such as a symbol assignment, then the output section
-will always be created, even if there are no matching input sections.
+The linker will ignore address assignments (@pxref{Output Section Address})
+on discarded output sections, except when the linker script defines
+symbols in the output section. In that case the linker will obey
+the address assignments, possibly advancing dot even though the
+section is discarded.
@cindex /DISCARD/
The special output section name @samp{/DISCARD/} may be used to discard
section named @samp{/DISCARD/} are not included in the output file.
@node Output Section Attributes
-@subsection Output section attributes
+@subsection Output Section Attributes
@cindex output section attributes
We showed above that the full description of an output section looked
like this:
@smallexample
@group
-@var{section} [@var{address}] [(@var{type})] : [AT(@var{lma})]
+@var{section} [@var{address}] [(@var{type})] :
+ [AT(@var{lma})] [ALIGN(@var{section_align})] [SUBALIGN(@var{subsection_align})]
@{
@var{output-section-command}
@var{output-section-command}
@menu
* Output Section Type:: Output section type
* Output Section LMA:: Output section LMA
+* Forced Output Alignment:: Forced Output Alignment
+* Forced Input Alignment:: Forced Input Alignment
* Output Section Region:: Output section region
* Output Section Phdr:: Output section phdr
* Output Section Fill:: Output section fill
@end menu
@node Output Section Type
-@subsubsection Output section type
+@subsubsection Output Section Type
Each output section may have a type. The type is a keyword in
parentheses. The following types are defined:
@end smallexample
@node Output Section LMA
-@subsubsection Output section LMA
+@subsubsection Output Section LMA
@kindex AT>@var{lma_region}
@kindex AT(@var{lma})
@cindex load address
an output section description sets the VMA (@pxref{Output Section
Address}).
-The linker will normally set the LMA equal to the VMA. You can change
-that by using the @code{AT} keyword. The expression @var{lma} that
-follows the @code{AT} keyword specifies the load address of the
-section. Alternatively, with @samp{AT>@var{lma_region}} expression,
-you may specify a memory region for the section's load address. @xref{MEMORY}.
+The expression @var{lma} that follows the @code{AT} keyword specifies
+the load address of the section.
+
+Alternatively, with @samp{AT>@var{lma_region}} expression, you may
+specify a memory region for the section's load address. @xref{MEMORY}.
+Note that if the section has not had a VMA assigned to it then the
+linker will use the @var{lma_region} as the VMA region as well.
+
+If neither @code{AT} nor @code{AT>} is specified for an allocatable
+section, the linker will set the LMA such that the difference between
+VMA and LMA for the section is the same as the preceding output
+section in the same region. If there is no preceding output section
+or the section is not allocatable, the linker will set the LMA equal
+to the VMA.
+@xref{Output Section Region}.
@cindex ROM initialized data
@cindex initialized data in ROM
@end group
@end smallexample
+@node Forced Output Alignment
+@subsubsection Forced Output Alignment
+@kindex ALIGN(@var{section_align})
+@cindex forcing output section alignment
+@cindex output section alignment
+You can increase an output section's alignment by using ALIGN.
+
+@node Forced Input Alignment
+@subsubsection Forced Input Alignment
+@kindex SUBALIGN(@var{subsection_align})
+@cindex forcing input section alignment
+@cindex input section alignment
+You can force input section alignment within an output section by using
+SUBALIGN. The value specified overrides any alignment given by input
+sections, whether larger or smaller.
+
@node Output Section Region
-@subsubsection Output section region
+@subsubsection Output Section Region
@kindex >@var{region}
@cindex section, assigning to memory region
@cindex memory regions and sections
@end smallexample
@node Output Section Phdr
-@subsubsection Output section phdr
+@subsubsection Output Section Phdr
@kindex :@var{phdr}
@cindex section, assigning to program header
@cindex program headers and sections
@end smallexample
@node Output Section Fill
-@subsubsection Output section fill
+@subsubsection Output Section Fill
@kindex =@var{fillexp}
@cindex section fill pattern
@cindex fill pattern, entire section
@samp{=@var{fillexp}}. @var{fillexp} is an expression
(@pxref{Expressions}). Any otherwise unspecified regions of memory
within the output section (for example, gaps left due to the required
-alignment of input sections) will be filled with the two least
-significant bytes of the value, repeated as necessary.
+alignment of input sections) will be filled with the value, repeated as
+necessary. If the fill expression is a simple hex number, ie. a string
+of hex digit starting with @samp{0x} and without a trailing @samp{k} or @samp{M}, then
+an arbitrarily long sequence of hex digits can be used to specify the
+fill pattern; Leading zeros become part of the pattern too. For all
+other cases, including extra parentheses or a unary @code{+}, the fill
+pattern is the four least significant bytes of the value of the
+expression. In all cases, the number is big-endian.
You can also change the fill value with a @code{FILL} command in the
-output section commands; see @ref{Output Section Data}.
+output section commands; (@pxref{Output Section Data}).
Here is a simple example:
@smallexample
@group
-SECTIONS @{ .text : @{ *(.text) @} =0x9090 @}
+SECTIONS @{ .text : @{ *(.text) @} =0x90909090 @}
@end group
@end smallexample
@node Overlay Description
-@subsection Overlay description
+@subsection Overlay Description
@kindex OVERLAY
@cindex overlays
An overlay description provides an easy way to describe sections which
NOCROSSREFS}.
For each section within the @code{OVERLAY}, the linker automatically
-defines two symbols. The symbol @code{__load_start_@var{secname}} is
+provides two symbols. The symbol @code{__load_start_@var{secname}} is
defined as the starting load address of the section. The symbol
@code{__load_stop_@var{secname}} is defined as the final load address of
the section. Any characters within @var{secname} which are not legal
This will define both @samp{.text0} and @samp{.text1} to start at
address 0x1000. @samp{.text0} will be loaded at address 0x4000, and
@samp{.text1} will be loaded immediately after @samp{.text0}. The
-following symbols will be defined: @code{__load_start_text0},
+following symbols will be defined if referenced: @code{__load_start_text0},
@code{__load_stop_text0}, @code{__load_start_text1},
@code{__load_stop_text1}.
@smallexample
@group
.text0 0x1000 : AT (0x4000) @{ o1/*.o(.text) @}
- __load_start_text0 = LOADADDR (.text0);
- __load_stop_text0 = LOADADDR (.text0) + SIZEOF (.text0);
+ PROVIDE (__load_start_text0 = LOADADDR (.text0));
+ PROVIDE (__load_stop_text0 = LOADADDR (.text0) + SIZEOF (.text0));
.text1 0x1000 : AT (0x4000 + SIZEOF (.text0)) @{ o2/*.o(.text) @}
- __load_start_text1 = LOADADDR (.text1);
- __load_stop_text1 = LOADADDR (.text1) + SIZEOF (.text1);
+ PROVIDE (__load_start_text1 = LOADADDR (.text1));
+ PROVIDE (__load_stop_text1 = LOADADDR (.text1) + SIZEOF (.text1));
. = 0x1000 + MAX (SIZEOF (.text0), SIZEOF (.text1));
@end group
@end smallexample
@node MEMORY
-@section MEMORY command
+@section MEMORY Command
@kindex MEMORY
@cindex memory regions
@cindex regions of memory
region. The region name has no meaning outside of the linker script.
Region names are stored in a separate name space, and will not conflict
with symbol names, file names, or section names. Each memory region
-must have a distinct name.
+must have a distinct name within the @code{MEMORY} command. However you can
+add later alias names to existing memory regions with the @ref{REGION_ALIAS}
+command.
@cindex memory region attributes
The @var{attr} string is an optional list of attributes that specify
@kindex ORIGIN =
@kindex o =
@kindex org =
-The @var{origin} is an expression for the start address of the memory
-region. The expression must evaluate to a constant before memory
-allocation is performed, which means that you may not use any section
-relative symbols. The keyword @code{ORIGIN} may be abbreviated to
-@code{org} or @code{o} (but not, for example, @code{ORG}).
+The @var{origin} is an numerical expression for the start address of
+the memory region. The expression must evaluate to a constant and it
+cannot involve any symbols. The keyword @code{ORIGIN} may be
+abbreviated to @code{org} or @code{o} (but not, for example,
+@code{ORG}).
@kindex LENGTH =
@kindex len =
@kindex l =
The @var{len} is an expression for the size in bytes of the memory
region. As with the @var{origin} expression, the expression must
-evaluate to a constant before memory allocation is performed. The
-keyword @code{LENGTH} may be abbreviated to @code{len} or @code{l}.
+be numerical only and must evaluate to a constant. The keyword
+@code{LENGTH} may be abbreviated to @code{len} or @code{l}.
In the following example, we specify that there are two memory regions
available for allocation: one starting at @samp{0} for 256 kilobytes,
output sections directed to a memory region are too large for the
region, the linker will issue an error message.
+It is possible to access the origin and length of a memory in an
+expression via the @code{ORIGIN(@var{memory})} and
+@code{LENGTH(@var{memory})} functions:
+
+@smallexample
+@group
+ _fstack = ORIGIN(ram) + LENGTH(ram) - 4;
+@end group
+@end smallexample
+
@node PHDRS
@section PHDRS Command
@kindex PHDRS
VERS_2.0 @{
bar1; bar2;
+ extern "C++" @{
+ ns::*;
+ "int f(int, double)";
+ @}
@} VERS_1.2;
@end smallexample
version node defined is @samp{VERS_1.1}; it has no other dependencies.
The script binds the symbol @samp{foo1} to @samp{VERS_1.1}. It reduces
a number of symbols to local scope so that they are not visible outside
-of the shared library.
+of the shared library; this is done using wildcard patterns, so that any
+symbol whose name begins with @samp{old}, @samp{original}, or @samp{new}
+is matched. The wildcard patterns available are the same as those used
+in the shell when matching filenames (also known as ``globbing'').
+However, if you specify the symbol name inside double quotes, then the
+name is treated as literal, rather than as a glob pattern.
Next, the version script defines node @samp{VERS_1.2}. This node
depends upon @samp{VERS_1.1}. The script binds the symbol @samp{foo2}
When the linker finds a symbol defined in a library which is not
specifically bound to a version node, it will effectively bind it to an
unspecified base version of the library. You can bind all otherwise
-unspecified symbols to a given version node by using @samp{global: *}
-somewhere in the version script.
+unspecified symbols to a given version node by using @samp{global: *;}
+somewhere in the version script. Note that it's slightly crazy to use
+wildcards in a global spec except on the last version node. Global
+wildcards elsewhere run the risk of accidentally adding symbols to the
+set exported for an old version. That's wrong since older versions
+ought to have a fixed set of symbols.
The names of the version nodes have no specific meaning other than what
they might suggest to the person reading them. The @samp{2.0} version
could just as well have appeared in between @samp{1.1} and @samp{1.2}.
However, this would be a confusing way to write a version script.
+Node name can be omitted, provided it is the only version node
+in the version script. Such version script doesn't assign any versions to
+symbols, only selects which symbols will be globally visible out and which
+won't.
+
+@smallexample
+@{ global: foo; bar; local: *; @};
+@end smallexample
+
When you link an application against a shared library that has versioned
symbols, the application itself knows which version of each symbol it
requires, and it also knows which version nodes it needs from each
in the C source file. This renames the function @samp{original_foo} to
be an alias for @samp{foo} bound to the version node @samp{VERS_1.1}.
The @samp{local:} directive can be used to prevent the symbol
-@samp{original_foo} from being exported.
+@samp{original_foo} from being exported. A @samp{.symver} directive
+takes precedence over a version script.
The second GNU extension is to allow multiple versions of the same
function to appear in a given shared library. In this way you can make
If you wish to bind a reference to a specific version of the symbol
within the shared library, you can use the aliases of convenience
-(i.e. @samp{old_foo}), or you can use the @samp{.symver} directive to
+(i.e., @samp{old_foo}), or you can use the @samp{.symver} directive to
specifically bind to an external version of the function in question.
You can also specify the language in the version script:
VERSION extern "lang" @{ version-script-commands @}
@end smallexample
-The supported @samp{lang}s are @samp{C}, @samp{C++}, and @samp{Java}.
+The supported @samp{lang}s are @samp{C}, @samp{C++}, and @samp{Java}.
The linker will iterate over the list of symbols at the link time and
demangle them according to @samp{lang} before matching them to the
patterns specified in @samp{version-script-commands}.
+Demangled names may contains spaces and other special characters. As
+described above, you can use a glob pattern to match demangled names,
+or you can use a double-quoted string to match the string exactly. In
+the latter case, be aware that minor differences (such as differing
+whitespace) between the version script and the demangler output will
+cause a mismatch. As the exact string generated by the demangler
+might change in the future, even if the mangled name does not, you
+should check that all of your version directives are behaving as you
+expect when you upgrade.
+
@node Expressions
@section Expressions in Linker Scripts
@cindex expressions
@menu
* Constants:: Constants
* Symbols:: Symbol Names
+* Orphan Sections:: Orphan Sections
* Location Counter:: The Location Counter
* Operators:: Operators
* Evaluation:: Evaluation
As in C, the linker considers an integer beginning with @samp{0} to be
octal, and an integer beginning with @samp{0x} or @samp{0X} to be
-hexadecimal. The linker considers other integers to be decimal.
+hexadecimal. Alternatively the linker accepts suffixes of @samp{h} or
+@samp{H} for hexadeciaml, @samp{o} or @samp{O} for octal, @samp{b} or
+@samp{B} for binary and @samp{d} or @samp{D} for decimal. Any integer
+value without a prefix or a suffix is considered to be decimal.
@cindex scaled integers
@cindex K and M integer suffixes
In addition, you can use the suffixes @code{K} and @code{M} to scale a
constant by
@c TEXI2ROFF-KILL
-@ifinfo
+@ifnottex
@c END TEXI2ROFF-KILL
@code{1024} or @code{1024*1024}
@c TEXI2ROFF-KILL
-@end ifinfo
+@end ifnottex
@tex
${\rm 1024}$ or ${\rm 1024}^2$
@end tex
@c END TEXI2ROFF-KILL
-respectively. For example, the following all refer to the same quantity:
+respectively. For example, the following
+all refer to the same quantity:
+
@smallexample
- _fourk_1 = 4K;
- _fourk_2 = 4096;
- _fourk_3 = 0x1000;
+_fourk_1 = 4K;
+_fourk_2 = 4096;
+_fourk_3 = 0x1000;
+_fourk_4 = 10000o;
@end smallexample
+Note - the @code{K} and @code{M} suffixes cannot be used in
+conjunction with the base suffixes mentioned above.
+
@node Symbols
@subsection Symbol Names
@cindex symbol names
specify a symbol which contains odd characters or has the same name as a
keyword by surrounding the symbol name in double quotes:
@smallexample
- "SECTION" = 9;
- "with a space" = "also with a space" + 10;
+"SECTION" = 9;
+"with a space" = "also with a space" + 10;
@end smallexample
Since symbols can contain many non-alphabetic characters, it is safest
to delimit symbols with spaces. For example, @samp{A-B} is one symbol,
whereas @samp{A - B} is an expression involving subtraction.
+@node Orphan Sections
+@subsection Orphan Sections
+@cindex orphan
+Orphan sections are sections present in the input files which
+are not explicitly placed into the output file by the linker
+script. The linker will still copy these sections into the
+output file, but it has to guess as to where they should be
+placed. The linker uses a simple heuristic to do this. It
+attempts to place orphan sections after non-orphan sections of the
+same attribute, such as code vs data, loadable vs non-loadable, etc.
+If there is not enough room to do this then it places
+at the end of the file.
+
+For ELF targets, the attribute of the section includes section type as
+well as section flag.
+
+If an orphaned section's name is representable as a C identifier then
+the linker will automatically @pxref{PROVIDE} two symbols:
+__start_SECNAME and __end_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 .
@cindex holes
Assigning a value to @code{.} will cause the location counter to be
moved. This may be used to create holes in the output section. The
-location counter may never be moved backwards.
+location counter may not be moved backwards inside an output section,
+and may not be moved backwards outside of an output section if so
+doing creates areas with overlapping LMAs.
@smallexample
SECTIONS
file2(.text)
. += 1000;
file3(.text)
- @} = 0x1234;
+ @} = 0x12345678;
@}
@end smallexample
@noindent
located at the beginning of the output section @samp{output}. It is
followed by a 1000 byte gap. Then the @samp{.text} section from
@file{file2} appears, also with a 1000 byte gap following before the
-@samp{.text} section from @file{file3}. The notation @samp{= 0x1234}
+@samp{.text} section from @file{file3}. The notation @samp{= 0x12345678}
specifies what data to write in the gaps (@pxref{Output Section Fill}).
@cindex dot inside sections
Note: @code{.} actually refers to the byte offset from the start of the
current containing object. Normally this is the @code{SECTIONS}
-statement, whoes start address is 0, hence @code{.} can be used as an
+statement, whose start address is 0, hence @code{.} can be used as an
absolute address. If @code{.} is used inside a section description
however, it refers to the byte offset from the start of that section,
not an absolute address. Thus in a script like this:
the values from the @samp{.data} input sections and before the end of
the @samp{.data} output section itself.
+@cindex dot outside sections
+Setting symbols to the value of the location counter outside of an
+output section statement can result in unexpected values if the linker
+needs to place orphan sections. For example, given the following:
+
+@smallexample
+SECTIONS
+@{
+ start_of_text = . ;
+ .text: @{ *(.text) @}
+ end_of_text = . ;
+
+ start_of_data = . ;
+ .data: @{ *(.data) @}
+ end_of_data = . ;
+@}
+@end smallexample
+
+If the linker needs to place some input section, e.g. @code{.rodata},
+not mentioned in the script, it might choose to place that section
+between @code{.text} and @code{.data}. You might think the linker
+should place @code{.rodata} on the blank line in the above script, but
+blank lines are of no particular significance to the linker. As well,
+the linker doesn't associate the above symbol names with their
+sections. Instead, it assumes that all assignments or other
+statements belong to the previous output section, except for the
+special case of an assignment to @code{.}. I.e., the linker will
+place the orphan @code{.rodata} section as if the script was written
+as follows:
+
+@smallexample
+SECTIONS
+@{
+ start_of_text = . ;
+ .text: @{ *(.text) @}
+ end_of_text = . ;
+
+ start_of_data = . ;
+ .rodata: @{ *(.rodata) @}
+ .data: @{ *(.data) @}
+ end_of_data = . ;
+@}
+@end smallexample
+
+This may or may not be the script author's intention for the value of
+@code{start_of_data}. One way to influence the orphan section
+placement is to assign the location counter to itself, as the linker
+assumes that an assignment to @code{.} is setting the start address of
+a following output section and thus should be grouped with that
+section. So you could write:
+
+@smallexample
+SECTIONS
+@{
+ start_of_text = . ;
+ .text: @{ *(.text) @}
+ end_of_text = . ;
+
+ . = . ;
+ start_of_data = . ;
+ .data: @{ *(.data) @}
+ end_of_data = . ;
+@}
+@end smallexample
+
+Now, the orphan @code{.rodata} section will be placed between
+@code{end_of_text} and @code{start_of_data}.
+
@need 2000
@node Operators
@subsection Operators
The linker recognizes the standard C set of arithmetic operators, with
the standard bindings and precedence levels:
@c TEXI2ROFF-KILL
-@ifinfo
+@ifnottex
@c END TEXI2ROFF-KILL
@smallexample
precedence associativity Operators Notes
(1) Prefix operators
(2) @xref{Assignments}.
@c TEXI2ROFF-KILL
-@end ifinfo
+@end ifnottex
@tex
\vskip \baselineskip
%"lispnarrowing" is the extra indent used generally for smallexample
@end group
@end smallexample
-@item ALIGN(@var{exp})
-@kindex ALIGN(@var{exp})
+@item ALIGN(@var{align})
+@itemx ALIGN(@var{exp},@var{align})
+@kindex ALIGN(@var{align})
+@kindex ALIGN(@var{exp},@var{align})
@cindex round up location counter
@cindex align location counter
-Return the location counter (@code{.}) aligned to the next @var{exp}
-boundary. @var{exp} must be an expression whose value is a power of
-two. This is equivalent to
-@smallexample
-(. + @var{exp} - 1) & ~(@var{exp} - 1)
-@end smallexample
-
-@code{ALIGN} doesn't change the value of the location counter---it just
-does arithmetic on it. Here is an example which aligns the output
-@code{.data} section to the next @code{0x2000} byte boundary after the
-preceding section and sets a variable within the section to the next
-@code{0x8000} boundary after the input sections:
+@cindex round up expression
+@cindex align expression
+Return the location counter (@code{.}) or arbitrary expression aligned
+to the next @var{align} boundary. The single operand @code{ALIGN}
+doesn't change the value of the location counter---it just does
+arithmetic on it. The two operand @code{ALIGN} allows an arbitrary
+expression to be aligned upwards (@code{ALIGN(@var{align})} is
+equivalent to @code{ALIGN(., @var{align})}).
+
+Here is an example which aligns the output @code{.data} section to the
+next @code{0x2000} byte boundary after the preceding section and sets a
+variable within the section to the next @code{0x8000} boundary after the
+input sections:
@smallexample
@group
SECTIONS @{ @dots{}
The builtin function @code{NEXT} is closely related to @code{ALIGN}.
+@item ALIGNOF(@var{section})
+@kindex ALIGNOF(@var{section})
+@cindex section alignment
+Return the alignment in bytes of the named @var{section}, if that section has
+been allocated. If the section has not been allocated when this is
+evaluated, the linker will report an error. In the following example,
+the alignment of the @code{.output} section is stored as the first
+value in that section.
+@smallexample
+@group
+SECTIONS@{ @dots{}
+ .output @{
+ LONG (ALIGNOF (.output))
+ @dots{}
+ @}
+@dots{} @}
+@end group
+@end smallexample
+
@item BLOCK(@var{exp})
@kindex BLOCK(@var{exp})
This is a synonym for @code{ALIGN}, for compatibility with older linker
scripts. It is most often seen when setting the address of an output
section.
+@item DATA_SEGMENT_ALIGN(@var{maxpagesize}, @var{commonpagesize})
+@kindex DATA_SEGMENT_ALIGN(@var{maxpagesize}, @var{commonpagesize})
+This is equivalent to either
+@smallexample
+(ALIGN(@var{maxpagesize}) + (. & (@var{maxpagesize} - 1)))
+@end smallexample
+or
+@smallexample
+(ALIGN(@var{maxpagesize}) + (. & (@var{maxpagesize} - @var{commonpagesize})))
+@end smallexample
+@noindent
+depending on whether the latter uses fewer @var{commonpagesize} sized pages
+for the data segment (area between the result of this expression and
+@code{DATA_SEGMENT_END}) than the former or not.
+If the latter form is used, it means @var{commonpagesize} bytes of runtime
+memory will be saved at the expense of up to @var{commonpagesize} wasted
+bytes in the on-disk file.
+
+This expression can only be used directly in @code{SECTIONS} commands, not in
+any output section descriptions and only once in the linker script.
+@var{commonpagesize} should be less or equal to @var{maxpagesize} and should
+be the system page size the object wants to be optimized for (while still
+working on system page sizes up to @var{maxpagesize}).
+
+@noindent
+Example:
+@smallexample
+ . = DATA_SEGMENT_ALIGN(0x10000, 0x2000);
+@end smallexample
+
+@item DATA_SEGMENT_END(@var{exp})
+@kindex DATA_SEGMENT_END(@var{exp})
+This defines the end of data segment for @code{DATA_SEGMENT_ALIGN}
+evaluation purposes.
+
+@smallexample
+ . = DATA_SEGMENT_END(.);
+@end smallexample
+
+@item DATA_SEGMENT_RELRO_END(@var{offset}, @var{exp})
+@kindex DATA_SEGMENT_RELRO_END(@var{offset}, @var{exp})
+This defines the end of the @code{PT_GNU_RELRO} segment when
+@samp{-z relro} option is used. Second argument is returned.
+When @samp{-z relro} option is not present, @code{DATA_SEGMENT_RELRO_END}
+does nothing, otherwise @code{DATA_SEGMENT_ALIGN} is padded so that
+@var{exp} + @var{offset} is aligned to the most commonly used page
+boundary for particular target. If present in the linker script,
+it must always come in between @code{DATA_SEGMENT_ALIGN} and
+@code{DATA_SEGMENT_END}.
+
+@smallexample
+ . = DATA_SEGMENT_RELRO_END(24, .);
+@end smallexample
+
@item DEFINED(@var{symbol})
@kindex DEFINED(@var{symbol})
@cindex symbol defaults
Return 1 if @var{symbol} is in the linker global symbol table and is
-defined, otherwise return 0. You can use this function to provide
+defined before the statement using DEFINED in the script, otherwise
+return 0. You can use this function to provide
default values for symbols. For example, the following script fragment
shows how to set a global symbol @samp{begin} to the first location in
the @samp{.text} section---but if a symbol called @samp{begin} already
@end group
@end smallexample
+@item LENGTH(@var{memory})
+@kindex LENGTH(@var{memory})
+Return the length of the memory region named @var{memory}.
+
@item LOADADDR(@var{section})
@kindex LOADADDR(@var{section})
@cindex section load address in expression
use the @code{MEMORY} command to define discontinuous memory for the
output file, the two functions are equivalent.
+@item ORIGIN(@var{memory})
+@kindex ORIGIN(@var{memory})
+Return the origin of the memory region named @var{memory}.
+
+@item SEGMENT_START(@var{segment}, @var{default})
+@kindex SEGMENT_START(@var{segment}, @var{default})
+Return the base address of the named @var{segment}. If an explicit
+value has been given for this segment (with a command-line @samp{-T}
+option) that value will be returned; otherwise the value will be
+@var{default}. At present, the @samp{-T} command-line option can only
+be used to set the base address for the ``text'', ``data'', and
+``bss'' sections, but you use @code{SEGMENT_START} with any segment
+name.
+
@item SIZEOF(@var{section})
@kindex SIZEOF(@var{section})
@cindex section size
@chapter Machine Dependent Features
@cindex machine dependencies
-@code{ld} has additional features on some platforms; the following
-sections describe them. Machines where @code{ld} has no additional
+@command{ld} has additional features on some platforms; the following
+sections describe them. Machines where @command{ld} has no additional
functionality are not listed.
@menu
-* H8/300:: @code{ld} and the H8/300
-* i960:: @code{ld} and the Intel 960 family
-* ARM:: @code{ld} and the ARM family
-* HPPA ELF32:: @code{ld} and HPPA 32-bit ELF
+@ifset H8300
+* H8/300:: @command{ld} and the H8/300
+@end ifset
+@ifset I960
+* i960:: @command{ld} and the Intel 960 family
+@end ifset
+@ifset ARM
+* ARM:: @command{ld} and the ARM family
+@end ifset
+@ifset HPPA
+* HPPA ELF32:: @command{ld} and HPPA 32-bit ELF
+@end ifset
+@ifset M68K
+* M68K:: @command{ld} and the Motorola 68K family
+@end ifset
+@ifset MMIX
+* MMIX:: @command{ld} and MMIX
+@end ifset
+@ifset MSP430
+* MSP430:: @command{ld} and MSP430
+@end ifset
+@ifset M68HC11
+* M68HC11/68HC12:: @code{ld} and the Motorola 68HC11 and 68HC12 families
+@end ifset
+@ifset POWERPC
+* PowerPC ELF32:: @command{ld} and PowerPC 32-bit ELF Support
+@end ifset
+@ifset POWERPC64
+* PowerPC64 ELF64:: @command{ld} and PowerPC64 64-bit ELF Support
+@end ifset
+@ifset SPU
+* SPU ELF:: @command{ld} and SPU ELF Support
+@end ifset
@ifset TICOFF
-* TI COFF:: @code{ld} and TI COFF
+* TI COFF:: @command{ld} and TI COFF
+@end ifset
+@ifset WIN32
+* WIN32:: @command{ld} and WIN32 (cygwin/mingw)
+@end ifset
+@ifset XTENSA
+* Xtensa:: @command{ld} and Xtensa Processors
@end ifset
@end menu
@end ifset
-@c FIXME! This could use @raisesections/@lowersections, but there seems to be a conflict
-@c between those and node-defaulting.
@ifset H8300
@ifclear GENERIC
@raisesections
@end ifclear
@node H8/300
-@section @code{ld} and the H8/300
+@section @command{ld} and the H8/300
@cindex H8/300 support
-For the H8/300, @code{ld} can perform these global optimizations when
+For the H8/300, @command{ld} can perform these global optimizations when
you specify the @samp{--relax} command-line option.
@table @emph
@cindex relaxing on H8/300
@item relaxing address modes
-@code{ld} finds all @code{jsr} and @code{jmp} instructions whose
+@command{ld} finds all @code{jsr} and @code{jmp} instructions whose
targets are within eight bits, and turns them into eight-bit
program-counter relative @code{bsr} and @code{bra} instructions,
respectively.
@cindex synthesizing on H8/300
@item synthesizing instructions
@c FIXME: specifically mov.b, or any mov instructions really?
-@code{ld} finds all @code{mov.b} instructions which use the
+@command{ld} finds all @code{mov.b} instructions which use the
sixteen-bit absolute address form, but refer to the top
page of memory, and changes them to use the eight-bit address form.
(That is: the linker turns @samp{mov.b @code{@@}@var{aa}:16} into
@samp{mov.b @code{@@}@var{aa}:8} whenever the address @var{aa} is in the
top page of memory).
+
+@item bit manipulation instructions
+@command{ld} finds all bit manipulation instructions like @code{band, bclr,
+biand, bild, bior, bist, bixor, bld, bnot, bor, bset, bst, btst, bxor}
+which use 32 bit and 16 bit absolute address form, but refer to the top
+page of memory, and changes them to use the 8 bit address form.
+(That is: the linker turns @samp{bset #xx:3,@code{@@}@var{aa}:32} into
+@samp{bset #xx:3,@code{@@}@var{aa}:8} whenever the address @var{aa} is in
+the top page of memory).
+
+@item system control instructions
+@command{ld} finds all @code{ldc.w, stc.w} instructions which use the
+32 bit absolute address form, but refer to the top page of memory, and
+changes them to use 16 bit address form.
+(That is: the linker turns @samp{ldc.w @code{@@}@var{aa}:32,ccr} into
+@samp{ldc.w @code{@@}@var{aa}:16,ccr} whenever the address @var{aa} is in
+the top page of memory).
@end table
@ifclear GENERIC
@end ifset
@ifclear GENERIC
-@ifset Hitachi
+@ifset Renesas
@c This stuff is pointless to say unless you're especially concerned
-@c with Hitachi chips; don't enable it for generic case, please.
-@node Hitachi
-@chapter @code{ld} and other Hitachi chips
+@c with Renesas chips; don't enable it for generic case, please.
+@node Renesas
+@chapter @command{ld} and Other Renesas Chips
-@code{ld} also supports the H8/300H, the H8/500, and the Hitachi SH. No
-special features, commands, or command-line options are required for
-these chips.
+@command{ld} also supports the Renesas (formerly Hitachi) H8/300H,
+H8/500, and SH chips. No special features, commands, or command-line
+options are required for these chips.
@end ifset
@end ifclear
@end ifclear
@node i960
-@section @code{ld} and the Intel 960 family
+@section @command{ld} and the Intel 960 Family
@cindex i960 support
libraries specific to each particular architecture, by including in the
search loop names suffixed with the string identifying the architecture.
-For example, if your @code{ld} command line included @w{@samp{-ACA}} as
+For example, if your @command{ld} command line included @w{@samp{-ACA}} as
well as @w{@samp{-ltry}}, the linker would look (in its built-in search
paths, and in any paths you specify with @samp{-L}) for a library with
the names
use will add another pair of name variants to search for when @w{@samp{-l}}
specifies a library.
-@cindex @code{--relax} on i960
+@cindex @option{--relax} on i960
@cindex relaxing on i960
-@code{ld} supports the @samp{--relax} option for the i960 family. If
-you specify @samp{--relax}, @code{ld} finds all @code{balx} and
+@command{ld} supports the @samp{--relax} option for the i960 family. If
+you specify @samp{--relax}, @command{ld} finds all @code{balx} and
@code{calx} instructions whose targets are within 24 bits, and turns
them into 24-bit program-counter relative @code{bal} and @code{cal}
-instructions, respectively. @code{ld} also turns @code{cal}
+instructions, respectively. @command{ld} also turns @code{cal}
instructions into @code{bal} instructions when it determines that the
target subroutine is a leaf routine (that is, the target subroutine does
not itself call any subroutines).
@end ifclear
@end ifset
+@ifset ARM
@ifclear GENERIC
@raisesections
@end ifclear
+@ifset M68HC11
+@ifclear GENERIC
+@raisesections
+@end ifclear
+
+@node M68HC11/68HC12
+@section @command{ld} and the Motorola 68HC11 and 68HC12 families
+
+@cindex M68HC11 and 68HC12 support
+
+@subsection Linker Relaxation
+
+For the Motorola 68HC11, @command{ld} can perform these global
+optimizations when you specify the @samp{--relax} command-line option.
+
+@table @emph
+@cindex relaxing on M68HC11
+@item relaxing address modes
+@command{ld} finds all @code{jsr} and @code{jmp} instructions whose
+targets are within eight bits, and turns them into eight-bit
+program-counter relative @code{bsr} and @code{bra} instructions,
+respectively.
+
+@command{ld} also looks at all 16-bit extended addressing modes and
+transforms them in a direct addressing mode when the address is in
+page 0 (between 0 and 0x0ff).
+
+@item relaxing gcc instruction group
+When @command{gcc} is called with @option{-mrelax}, it can emit group
+of instructions that the linker can optimize to use a 68HC11 direct
+addressing mode. These instructions consists of @code{bclr} or
+@code{bset} instructions.
+
+@end table
+
+@subsection Trampoline Generation
+
+@cindex trampoline generation on M68HC11
+@cindex trampoline generation on M68HC12
+For 68HC11 and 68HC12, @command{ld} can generate trampoline code to
+call a far function using a normal @code{jsr} instruction. The linker
+will also change the relocation to some far function to use the
+trampoline address instead of the function address. This is typically the
+case when a pointer to a function is taken. The pointer will in fact
+point to the function trampoline.
+
+@ifclear GENERIC
+@lowersections
+@end ifclear
+@end ifset
+
@node ARM
-@section @code{ld}'s support for interworking between ARM and Thumb code
+@section @command{ld} and the ARM family
@cindex ARM interworking support
@kindex --support-old-code
-For the ARM, @code{ld} will generate code stubs to allow functions calls
-betweem ARM and Thumb code. These stubs only work with code that has
+For the ARM, @command{ld} will generate code stubs to allow functions calls
+between ARM and Thumb code. These stubs only work with code that has
been compiled and assembled with the @samp{-mthumb-interwork} command
line option. If it is necessary to link with old ARM object files or
libraries, which have not been compiled with the -mthumb-interwork
branched to using a BX instruction, and the program will start
executing in Thumb mode straight away.
+@cindex PE import table prefixing
+@kindex --use-nul-prefixed-import-tables
+The @samp{--use-nul-prefixed-import-tables} switch is specifying, that
+the import tables idata4 and idata5 have to be generated with a zero
+elememt prefix for import libraries. This is the old style to generate
+import tables. By default this option is turned off.
+
+@cindex BE8
+@kindex --be8
+The @samp{--be8} switch instructs @command{ld} to generate BE8 format
+executables. This option is only valid when linking big-endian objects.
+The resulting image will contain big-endian data and little-endian code.
+
+@cindex TARGET1
+@kindex --target1-rel
+@kindex --target1-abs
+The @samp{R_ARM_TARGET1} relocation is typically used for entries in the
+@samp{.init_array} section. It is interpreted as either @samp{R_ARM_REL32}
+or @samp{R_ARM_ABS32}, depending on the target. The @samp{--target1-rel}
+and @samp{--target1-abs} switches override the default.
+
+@cindex TARGET2
+@kindex --target2=@var{type}
+The @samp{--target2=type} switch overrides the default definition of the
+@samp{R_ARM_TARGET2} relocation. Valid values for @samp{type}, their
+meanings, and target defaults are as follows:
+@table @samp
+@item rel
+@samp{R_ARM_REL32} (arm*-*-elf, arm*-*-eabi)
+@item abs
+@samp{R_ARM_ABS32} (arm*-*-symbianelf)
+@item got-rel
+@samp{R_ARM_GOT_PREL} (arm*-*-linux, arm*-*-*bsd)
+@end table
+
+@cindex FIX_V4BX
+@kindex --fix-v4bx
+The @samp{R_ARM_V4BX} relocation (defined by the ARM AAELF
+specification) enables objects compiled for the ARMv4 architecture to be
+interworking-safe when linked with other objects compiled for ARMv4t, but
+also allows pure ARMv4 binaries to be built from the same ARMv4 objects.
+
+In the latter case, the switch @option{--fix-v4bx} must be passed to the
+linker, which causes v4t @code{BX rM} instructions to be rewritten as
+@code{MOV PC,rM}, since v4 processors do not have a @code{BX} instruction.
+
+In the former case, the switch should not be used, and @samp{R_ARM_V4BX}
+relocations are ignored.
+
+@cindex FIX_V4BX_INTERWORKING
+@kindex --fix-v4bx-interworking
+Replace @code{BX rM} instructions identified by @samp{R_ARM_V4BX}
+relocations with a branch to the following veneer:
+
+@smallexample
+TST rM, #1
+MOVEQ PC, rM
+BX Rn
+@end smallexample
+
+This allows generation of libraries/applications that work on ARMv4 cores
+and are still interworking safe. Note that the above veneer clobbers the
+condition flags, so may cause incorrect progrm behavior in rare cases.
+
+@cindex USE_BLX
+@kindex --use-blx
+The @samp{--use-blx} switch enables the linker to use ARM/Thumb
+BLX instructions (available on ARMv5t and above) in various
+situations. Currently it is used to perform calls via the PLT from Thumb
+code using BLX rather than using BX and a mode-switching stub before
+each PLT entry. This should lead to such calls executing slightly faster.
+
+This option is enabled implicitly for SymbianOS, so there is no need to
+specify it if you are using that target.
+
+@cindex VFP11_DENORM_FIX
+@kindex --vfp11-denorm-fix
+The @samp{--vfp11-denorm-fix} switch enables a link-time workaround for a
+bug in certain VFP11 coprocessor hardware, which sometimes allows
+instructions with denorm operands (which must be handled by support code)
+to have those operands overwritten by subsequent instructions before
+the support code can read the intended values.
+
+The bug may be avoided in scalar mode if you allow at least one
+intervening instruction between a VFP11 instruction which uses a register
+and another instruction which writes to the same register, or at least two
+intervening instructions if vector mode is in use. The bug only affects
+full-compliance floating-point mode: you do not need this workaround if
+you are using "runfast" mode. Please contact ARM for further details.
+
+If you know you are using buggy VFP11 hardware, you can
+enable this workaround by specifying the linker option
+@samp{--vfp-denorm-fix=scalar} if you are using the VFP11 scalar
+mode only, or @samp{--vfp-denorm-fix=vector} if you are using
+vector mode (the latter also works for scalar code). The default is
+@samp{--vfp-denorm-fix=none}.
+
+If the workaround is enabled, instructions are scanned for
+potentially-troublesome sequences, and a veneer is created for each
+such sequence which may trigger the erratum. The veneer consists of the
+first instruction of the sequence and a branch back to the subsequent
+instruction. The original instruction is then replaced with a branch to
+the veneer. The extra cycles required to call and return from the veneer
+are sufficient to avoid the erratum in both the scalar and vector cases.
+
+@cindex NO_ENUM_SIZE_WARNING
+@kindex --no-enum-size-warning
+The @option{--no-enum-size-warning} switch prevents the linker from
+warning when linking object files that specify incompatible EABI
+enumeration size attributes. For example, with this switch enabled,
+linking of an object file using 32-bit enumeration values with another
+using enumeration values fitted into the smallest possible space will
+not be diagnosed.
+
+@cindex NO_WCHAR_SIZE_WARNING
+@kindex --no-wchar-size-warning
+The @option{--no-wchar-size-warning} switch prevents the linker from
+warning when linking object files that specify incompatible EABI
+@code{wchar_t} size attributes. For example, with this switch enabled,
+linking of an object file using 32-bit @code{wchar_t} values with another
+using 16-bit @code{wchar_t} values will not be diagnosed.
+
+@cindex PIC_VENEER
+@kindex --pic-veneer
+The @samp{--pic-veneer} switch makes the linker use PIC sequences for
+ARM/Thumb interworking veneers, even if the rest of the binary
+is not PIC. This avoids problems on uClinux targets where
+@samp{--emit-relocs} is used to generate relocatable binaries.
+
+@cindex STUB_GROUP_SIZE
+@kindex --stub-group-size=@var{N}
+The linker will automatically generate and insert small sequences of
+code into a linked ARM ELF executable whenever an attempt is made to
+perform a function call to a symbol that is too far away. The
+placement of these sequences of instructions - called stubs - is
+controlled by the command line option @option{--stub-group-size=N}.
+The placement is important because a poor choice can create a need for
+duplicate stubs, increasing the code sizw. The linker will try to
+group stubs together in order to reduce interruptions to the flow of
+code, but it needs guidance as to how big these groups should be and
+where they should be placed.
+
+The value of @samp{N}, the parameter to the
+@option{--stub-group-size=} option controls where the stub groups are
+placed. If it is negative then all stubs are placed after the first
+branch that needs them. If it is positive then the stubs can be
+placed either before or after the branches that need them. If the
+value of @samp{N} is 1 (either +1 or -1) then the linker will choose
+exactly where to place groups of stubs, using its built in heuristics.
+A value of @samp{N} greater than 1 (or smaller than -1) tells the
+linker that a single group of stubs can service at most @samp{N} bytes
+from the input sections.
+
+The default, if @option{--stub-group-size=} is not specified, is
+@samp{N = +1}.
+
+Farcalls stubs insertion is fully supported for the ARM-EABI target
+only, because it relies on object files properties not present
+otherwise.
+
+@ifclear GENERIC
+@lowersections
+@end ifclear
+@end ifset
+
+@ifset HPPA
+@ifclear GENERIC
+@raisesections
+@end ifclear
+
@node HPPA ELF32
-@section @code{ld} and HPPA 32-bit ELF support
+@section @command{ld} and HPPA 32-bit ELF Support
@cindex HPPA multiple sub-space stubs
@kindex --multi-subspace
-When generating a shared library, @code{ld} will by default generate
+When generating a shared library, @command{ld} will by default generate
import stubs suitable for use with a single sub-space application.
-The @samp{--multi-subspace} switch causes @code{ld} to generate export
+The @samp{--multi-subspace} switch causes @command{ld} to generate export
stubs, and different (larger) import stubs suitable for use with
multiple sub-spaces.
@cindex HPPA stub grouping
@kindex --stub-group-size=@var{N}
-Long branch stubs and import/export stubs are placed by @code{ld} in
+Long branch stubs and import/export stubs are placed by @command{ld} in
stub sections located between groups of input sections.
@samp{--stub-group-size} specifies the maximum size of a group of input
sections handled by one stub section. Since branch offsets are signed,
A negative value for @samp{N} chooses this scheme, ensuring that
branches to stubs always use a negative offset. Two special values of
@samp{N} are recognized, @samp{1} and @samp{-1}. These both instruct
-@code{ld} to automatically size input section groups for the branch types
+@command{ld} to automatically size input section groups for the branch types
+detected, with the same behaviour regarding stub placement as other
+positive or negative values of @samp{N} respectively.
+
+Note that @samp{--stub-group-size} does not split input sections. A
+single input section larger than the group size specified will of course
+create a larger group (of one section). If input sections are too
+large, it may not be possible for a branch to reach its stub.
+
+@ifclear GENERIC
+@lowersections
+@end ifclear
+@end ifset
+
+@ifset M68K
+@ifclear GENERIC
+@raisesections
+@end ifclear
+
+@node M68K
+@section @command{ld} and the Motorola 68K family
+
+@cindex Motorola 68K GOT generation
+@kindex --got=@var{type}
+The @samp{--got=@var{type}} option lets you choose the GOT generation scheme.
+The choices are @samp{single}, @samp{negative}, @samp{multigot} and
+@samp{target}. When @samp{target} is selected the linker chooses
+the default GOT generation scheme for the current target.
+@samp{single} tells the linker to generate a single GOT with
+entries only at non-negative offsets.
+@samp{negative} instructs the linker to generate a single GOT with
+entries at both negative and positive offsets. Not all environments
+support such GOTs.
+@samp{multigot} allows the linker to generate several GOTs in the
+output file. All GOT references from a single input object
+file access the same GOT, but references from different input object
+files might access different GOTs. Not all environments support such GOTs.
+
+@ifclear GENERIC
+@lowersections
+@end ifclear
+@end ifset
+
+@ifset MMIX
+@ifclear GENERIC
+@raisesections
+@end ifclear
+
+@node MMIX
+@section @code{ld} and MMIX
+For MMIX, there is a choice of generating @code{ELF} object files or
+@code{mmo} object files when linking. The simulator @code{mmix}
+understands the @code{mmo} format. The binutils @code{objcopy} utility
+can translate between the two formats.
+
+There is one special section, the @samp{.MMIX.reg_contents} section.
+Contents in this section is assumed to correspond to that of global
+registers, and symbols referring to it are translated to special symbols,
+equal to registers. In a final link, the start address of the
+@samp{.MMIX.reg_contents} section corresponds to the first allocated
+global register multiplied by 8. Register @code{$255} is not included in
+this section; it is always set to the program entry, which is at the
+symbol @code{Main} for @code{mmo} files.
+
+Global symbols with the prefix @code{__.MMIX.start.}, for example
+@code{__.MMIX.start..text} and @code{__.MMIX.start..data} are special.
+The default linker script uses these to set the default start address
+of a section.
+
+Initial and trailing multiples of zero-valued 32-bit words in a section,
+are left out from an mmo file.
+
+@ifclear GENERIC
+@lowersections
+@end ifclear
+@end ifset
+
+@ifset MSP430
+@ifclear GENERIC
+@raisesections
+@end ifclear
+
+@node MSP430
+@section @code{ld} and MSP430
+For the MSP430 it is possible to select the MPU architecture. The flag @samp{-m [mpu type]}
+will select an appropriate linker script for selected MPU type. (To get a list of known MPUs
+just pass @samp{-m help} option to the linker).
+
+@cindex MSP430 extra sections
+The linker will recognize some extra sections which are MSP430 specific:
+
+@table @code
+@item @samp{.vectors}
+Defines a portion of ROM where interrupt vectors located.
+
+@item @samp{.bootloader}
+Defines the bootloader portion of the ROM (if applicable). Any code
+in this section will be uploaded to the MPU.
+
+@item @samp{.infomem}
+Defines an information memory section (if applicable). Any code in
+this section will be uploaded to the MPU.
+
+@item @samp{.infomemnobits}
+This is the same as the @samp{.infomem} section except that any code
+in this section will not be uploaded to the MPU.
+
+@item @samp{.noinit}
+Denotes a portion of RAM located above @samp{.bss} section.
+
+The last two sections are used by gcc.
+@end table
+
+@ifclear GENERIC
+@lowersections
+@end ifclear
+@end ifset
+
+@ifset POWERPC
+@ifclear GENERIC
+@raisesections
+@end ifclear
+
+@node PowerPC ELF32
+@section @command{ld} and PowerPC 32-bit ELF Support
+@cindex PowerPC long branches
+@kindex --relax on PowerPC
+Branches on PowerPC processors are limited to a signed 26-bit
+displacement, which may result in @command{ld} giving
+@samp{relocation truncated to fit} errors with very large programs.
+@samp{--relax} enables the generation of trampolines that can access
+the entire 32-bit address space. These trampolines are inserted at
+section boundaries, so may not themselves be reachable if an input
+section exceeds 33M in size.
+
+@cindex PowerPC ELF32 options
+@table @option
+@cindex PowerPC PLT
+@kindex --bss-plt
+@item --bss-plt
+Current PowerPC GCC accepts a @samp{-msecure-plt} option that
+generates code capable of using a newer PLT and GOT layout that has
+the security advantage of no executable section ever needing to be
+writable and no writable section ever being executable. PowerPC
+@command{ld} will generate this layout, including stubs to access the
+PLT, if all input files (including startup and static libraries) were
+compiled with @samp{-msecure-plt}. @samp{--bss-plt} forces the old
+BSS PLT (and GOT layout) which can give slightly better performance.
+
+@kindex --secure-plt
+@item --secure-plt
+@command{ld} will use the new PLT and GOT layout if it is linking new
+@samp{-fpic} or @samp{-fPIC} code, but does not do so automatically
+when linking non-PIC code. This option requests the new PLT and GOT
+layout. A warning will be given if some object file requires the old
+style BSS PLT.
+
+@cindex PowerPC GOT
+@kindex --sdata-got
+@item --sdata-got
+The new secure PLT and GOT are placed differently relative to other
+sections compared to older BSS PLT and GOT placement. The location of
+@code{.plt} must change because the new secure PLT is an initialized
+section while the old PLT is uninitialized. The reason for the
+@code{.got} change is more subtle: The new placement allows
+@code{.got} to be read-only in applications linked with
+@samp{-z relro -z now}. However, this placement means that
+@code{.sdata} cannot always be used in shared libraries, because the
+PowerPC ABI accesses @code{.sdata} in shared libraries from the GOT
+pointer. @samp{--sdata-got} forces the old GOT placement. PowerPC
+GCC doesn't use @code{.sdata} in shared libraries, so this option is
+really only useful for other compilers that may do so.
+
+@cindex PowerPC stub symbols
+@kindex --emit-stub-syms
+@item --emit-stub-syms
+This option causes @command{ld} to label linker stubs with a local
+symbol that encodes the stub type and destination.
+
+@cindex PowerPC TLS optimization
+@kindex --no-tls-optimize
+@item --no-tls-optimize
+PowerPC @command{ld} normally performs some optimization of code
+sequences used to access Thread-Local Storage. Use this option to
+disable the optimization.
+@end table
+
+@ifclear GENERIC
+@lowersections
+@end ifclear
+@end ifset
+
+@ifset POWERPC64
+@ifclear GENERIC
+@raisesections
+@end ifclear
+
+@node PowerPC64 ELF64
+@section @command{ld} and PowerPC64 64-bit ELF Support
+
+@cindex PowerPC64 ELF64 options
+@table @option
+@cindex PowerPC64 stub grouping
+@kindex --stub-group-size
+@item --stub-group-size
+Long branch stubs, PLT call stubs and TOC adjusting stubs are placed
+by @command{ld} in stub sections located between groups of input sections.
+@samp{--stub-group-size} specifies the maximum size of a group of input
+sections handled by one stub section. Since branch offsets are signed,
+a stub section may serve two groups of input sections, one group before
+the stub section, and one group after it. However, when using
+conditional branches that require stubs, it may be better (for branch
+prediction) that stub sections only serve one group of input sections.
+A negative value for @samp{N} chooses this scheme, ensuring that
+branches to stubs always use a negative offset. Two special values of
+@samp{N} are recognized, @samp{1} and @samp{-1}. These both instruct
+@command{ld} to automatically size input section groups for the branch types
detected, with the same behaviour regarding stub placement as other
positive or negative values of @samp{N} respectively.
create a larger group (of one section). If input sections are too
large, it may not be possible for a branch to reach its stub.
+@cindex PowerPC64 stub symbols
+@kindex --emit-stub-syms
+@item --emit-stub-syms
+This option causes @command{ld} to label linker stubs with a local
+symbol that encodes the stub type and destination.
+
+@cindex PowerPC64 dot symbols
+@kindex --dotsyms
+@kindex --no-dotsyms
+@item --dotsyms, --no-dotsyms
+These two options control how @command{ld} interprets version patterns
+in a version script. Older PowerPC64 compilers emitted both a
+function descriptor symbol with the same name as the function, and a
+code entry symbol with the name prefixed by a dot (@samp{.}). To
+properly version a function @samp{foo}, the version script thus needs
+to control both @samp{foo} and @samp{.foo}. The option
+@samp{--dotsyms}, on by default, automatically adds the required
+dot-prefixed patterns. Use @samp{--no-dotsyms} to disable this
+feature.
+
+@cindex PowerPC64 TLS optimization
+@kindex --no-tls-optimize
+@item --no-tls-optimize
+PowerPC64 @command{ld} normally performs some optimization of code
+sequences used to access Thread-Local Storage. Use this option to
+disable the optimization.
+
+@cindex PowerPC64 OPD optimization
+@kindex --no-opd-optimize
+@item --no-opd-optimize
+PowerPC64 @command{ld} normally removes @code{.opd} section entries
+corresponding to deleted link-once functions, or functions removed by
+the action of @samp{--gc-sections} or linker script @code{/DISCARD/}.
+Use this option to disable @code{.opd} optimization.
+
+@cindex PowerPC64 OPD spacing
+@kindex --non-overlapping-opd
+@item --non-overlapping-opd
+Some PowerPC64 compilers have an option to generate compressed
+@code{.opd} entries spaced 16 bytes apart, overlapping the third word,
+the static chain pointer (unused in C) with the first word of the next
+entry. This option expands such entries to the full 24 bytes.
+
+@cindex PowerPC64 TOC optimization
+@kindex --no-toc-optimize
+@item --no-toc-optimize
+PowerPC64 @command{ld} normally removes unused @code{.toc} section
+entries. Such entries are detected by examining relocations that
+reference the TOC in code sections. A reloc in a deleted code section
+marks a TOC word as unneeded, while a reloc in a kept code section
+marks a TOC word as needed. Since the TOC may reference itself, TOC
+relocs are also examined. TOC words marked as both needed and
+unneeded will of course be kept. TOC words without any referencing
+reloc are assumed to be part of a multi-word entry, and are kept or
+discarded as per the nearest marked preceding word. This works
+reliably for compiler generated code, but may be incorrect if assembly
+code is used to insert TOC entries. Use this option to disable the
+optimization.
+
+@cindex PowerPC64 multi-TOC
+@kindex --no-multi-toc
+@item --no-multi-toc
+By default, PowerPC64 GCC generates code for a TOC model where TOC
+entries are accessed with a 16-bit offset from r2. This limits the
+total TOC size to 64K. PowerPC64 @command{ld} extends this limit by
+grouping code sections such that each group uses less than 64K for its
+TOC entries, then inserts r2 adjusting stubs between inter-group
+calls. @command{ld} does not split apart input sections, so cannot
+help if a single input file has a @code{.toc} section that exceeds
+64K, most likely from linking multiple files with @command{ld -r}.
+Use this option to turn off this feature.
+@end table
+
+@ifclear GENERIC
+@lowersections
+@end ifclear
+@end ifset
+
+@ifset SPU
+@ifclear GENERIC
+@raisesections
+@end ifclear
+
+@node SPU ELF
+@section @command{ld} and SPU ELF Support
+
+@cindex SPU ELF options
+@table @option
+
+@cindex SPU plugins
+@kindex --plugin
+@item --plugin
+This option marks an executable as a PIC plugin module.
+
+@cindex SPU overlays
+@kindex --no-overlays
+@item --no-overlays
+Normally, @command{ld} recognizes calls to functions within overlay
+regions, and redirects such calls to an overlay manager via a stub.
+@command{ld} also provides a built-in overlay manager. This option
+turns off all this special overlay handling.
+
+@cindex SPU overlay stub symbols
+@kindex --emit-stub-syms
+@item --emit-stub-syms
+This option causes @command{ld} to label overlay stubs with a local
+symbol that encodes the stub type and destination.
+
+@cindex SPU extra overlay stubs
+@kindex --extra-overlay-stubs
+@item --extra-overlay-stubs
+This option causes @command{ld} to add overlay call stubs on all
+function calls out of overlay regions. Normally stubs are not added
+on calls to non-overlay regions.
+
+@cindex SPU local store size
+@kindex --local-store=lo:hi
+@item --local-store=lo:hi
+@command{ld} usually checks that a final executable for SPU fits in
+the address range 0 to 256k. This option may be used to change the
+range. Disable the check entirely with @option{--local-store=0:0}.
+
+@cindex SPU
+@kindex --stack-analysis
+@item --stack-analysis
+SPU local store space is limited. Over-allocation of stack space
+unnecessarily limits space available for code and data, while
+under-allocation results in runtime failures. If given this option,
+@command{ld} will provide an estimate of maximum stack usage.
+@command{ld} does this by examining symbols in code sections to
+determine the extents of functions, and looking at function prologues
+for stack adjusting instructions. A call-graph is created by looking
+for relocations on branch instructions. The graph is then searched
+for the maximum stack usage path. Note that this analysis does not
+find calls made via function pointers, and does not handle recursion
+and other cycles in the call graph. Stack usage may be
+under-estimated if your code makes such calls. Also, stack usage for
+dynamic allocation, e.g. alloca, will not be detected. If a link map
+is requested, detailed information about each function's stack usage
+and calls will be given.
+
+@cindex SPU
+@kindex --emit-stack-syms
+@item --emit-stack-syms
+This option, if given along with @option{--stack-analysis} will result
+in @command{ld} emitting stack sizing symbols for each function.
+These take the form @code{__stack_<function_name>} for global
+functions, and @code{__stack_<number>_<function_name>} for static
+functions. @code{<number>} is the section id in hex. The value of
+such symbols is the stack requirement for the corresponding function.
+The symbol size will be zero, type @code{STT_NOTYPE}, binding
+@code{STB_LOCAL}, and section @code{SHN_ABS}.
+@end table
+
+@ifclear GENERIC
+@lowersections
+@end ifclear
+@end ifset
+
@ifset TICOFF
+@ifclear GENERIC
+@raisesections
+@end ifclear
+
@node TI COFF
-@section @code{ld}'s support for various TI COFF versions
+@section @command{ld}'s Support for Various TI COFF Versions
@cindex TI COFF versions
@kindex --format=@var{version}
The @samp{--format} switch allows selection of one of the various
TI COFF versions. The latest of this writing is 2; versions 0 and 1 are
also supported. The TI COFF versions also vary in header byte-order
-format; @code{ld} will read any version or byte order, but the output
+format; @command{ld} will read any version or byte order, but the output
header format depends on the default specified by the specific target.
+
+@ifclear GENERIC
+@lowersections
+@end ifclear
+@end ifset
+
+@ifset WIN32
+@ifclear GENERIC
+@raisesections
+@end ifclear
+
+@node WIN32
+@section @command{ld} and WIN32 (cygwin/mingw)
+
+This section describes some of the win32 specific @command{ld} issues.
+See @ref{Options,,Command Line Options} for detailed description of the
+command line options mentioned here.
+
+@table @emph
+@cindex import libraries
+@item import libraries
+The standard Windows linker creates and uses so-called import
+libraries, which contains information for linking to dll's. They are
+regular static archives and are handled as any other static
+archive. The cygwin and mingw ports of @command{ld} have specific
+support for creating such libraries provided with the
+@samp{--out-implib} command line option.
+
+@item exporting DLL symbols
+@cindex exporting DLL symbols
+The cygwin/mingw @command{ld} has several ways to export symbols for dll's.
+
+@table @emph
+@item using auto-export functionality
+@cindex using auto-export functionality
+By default @command{ld} exports symbols with the auto-export functionality,
+which is controlled by the following command line options:
+
+@itemize
+@item --export-all-symbols [This is the default]
+@item --exclude-symbols
+@item --exclude-libs
+@item --exclude-modules-for-implib
+@end itemize
+
+If, however, @samp{--export-all-symbols} is not given explicitly on the
+command line, then the default auto-export behavior will be @emph{disabled}
+if either of the following are true:
+
+@itemize
+@item A DEF file is used.
+@item Any symbol in any object file was marked with the __declspec(dllexport) attribute.
+@end itemize
+
+@item using a DEF file
+@cindex using a DEF file
+Another way of exporting symbols is using a DEF file. A DEF file is
+an ASCII file containing definitions of symbols which should be
+exported when a dll is created. Usually it is named @samp{<dll
+name>.def} and is added as any other object file to the linker's
+command line. The file's name must end in @samp{.def} or @samp{.DEF}.
+
+@example
+gcc -o <output> <objectfiles> <dll name>.def
+@end example
+
+Using a DEF file turns off the normal auto-export behavior, unless the
+@samp{--export-all-symbols} option is also used.
+
+Here is an example of a DEF file for a shared library called @samp{xyz.dll}:
+
+@example
+LIBRARY "xyz.dll" BASE=0x20000000
+
+EXPORTS
+foo
+bar
+_bar = bar
+another_foo = abc.dll.afoo
+var1 DATA
+@end example
+
+This example defines a DLL with a non-default base address and five
+symbols in the export table. The third exported symbol @code{_bar} is an
+alias for the second. The fourth symbol, @code{another_foo} is resolved
+by "forwarding" to another module and treating it as an alias for
+@code{afoo} exported from the DLL @samp{abc.dll}. The final symbol
+@code{var1} is declared to be a data object.
+
+The optional @code{LIBRARY <name>} command indicates the @emph{internal}
+name of the output DLL. If @samp{<name>} does not include a suffix,
+the default library suffix, @samp{.DLL} is appended.
+
+When the .DEF file is used to build an application, rather than a
+library, the @code{NAME <name>} command should be used instead of
+@code{LIBRARY}. If @samp{<name>} does not include a suffix, the default
+executable suffix, @samp{.EXE} is appended.
+
+With either @code{LIBRARY <name>} or @code{NAME <name>} the optional
+specification @code{BASE = <number>} may be used to specify a
+non-default base address for the image.
+
+If neither @code{LIBRARY <name>} nor @code{NAME <name>} is specified,
+or they specify an empty string, the internal name is the same as the
+filename specified on the command line.
+
+The complete specification of an export symbol is:
+
+@example
+EXPORTS
+ ( ( ( <name1> [ = <name2> ] )
+ | ( <name1> = <module-name> . <external-name>))
+ [ @@ <integer> ] [NONAME] [DATA] [CONSTANT] [PRIVATE] ) *
+@end example
+
+Declares @samp{<name1>} as an exported symbol from the DLL, or declares
+@samp{<name1>} as an exported alias for @samp{<name2>}; or declares
+@samp{<name1>} as a "forward" alias for the symbol
+@samp{<external-name>} in the DLL @samp{<module-name>}.
+Optionally, the symbol may be exported by the specified ordinal
+@samp{<integer>} alias.
+
+The optional keywords that follow the declaration indicate:
+
+@code{NONAME}: Do not put the symbol name in the DLL's export table. It
+will still be exported by its ordinal alias (either the value specified
+by the .def specification or, otherwise, the value assigned by the
+linker). The symbol name, however, does remain visible in the import
+library (if any), unless @code{PRIVATE} is also specified.
+
+@code{DATA}: The symbol is a variable or object, rather than a function.
+The import lib will export only an indirect reference to @code{foo} as
+the symbol @code{_imp__foo} (ie, @code{foo} must be resolved as
+@code{*_imp__foo}).
+
+@code{CONSTANT}: Like @code{DATA}, but put the undecorated @code{foo} as
+well as @code{_imp__foo} into the import library. Both refer to the
+read-only import address table's pointer to the variable, not to the
+variable itself. This can be dangerous. If the user code fails to add
+the @code{dllimport} attribute and also fails to explicitly add the
+extra indirection that the use of the attribute enforces, the
+application will behave unexpectedly.
+
+@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
+the DLL without an import library.
+
+See ld/deffilep.y in the binutils sources for the full specification of
+other DEF file statements
+
+@cindex creating a DEF file
+While linking a shared dll, @command{ld} is able to create a DEF file
+with the @samp{--output-def <file>} command line option.
+
+@item Using decorations
+@cindex Using decorations
+Another way of marking symbols for export is to modify the source code
+itself, so that when building the DLL each symbol to be exported is
+declared as:
+
+@example
+__declspec(dllexport) int a_variable
+__declspec(dllexport) void a_function(int with_args)
+@end example
+
+All such symbols will be exported from the DLL. If, however,
+any of the object files in the DLL contain symbols decorated in
+this way, then the normal auto-export behavior is disabled, unless
+the @samp{--export-all-symbols} option is also used.
+
+Note that object files that wish to access these symbols must @emph{not}
+decorate them with dllexport. Instead, they should use dllimport,
+instead:
+
+@example
+__declspec(dllimport) int a_variable
+__declspec(dllimport) void a_function(int with_args)
+@end example
+
+This complicates the structure of library header files, because
+when included by the library itself the header must declare the
+variables and functions as dllexport, but when included by client
+code the header must declare them as dllimport. There are a number
+of idioms that are typically used to do this; often client code can
+omit the __declspec() declaration completely. See
+@samp{--enable-auto-import} and @samp{automatic data imports} for more
+information.
+@end table
+
+@cindex automatic data imports
+@item automatic data imports
+The standard Windows dll format supports data imports from dlls only
+by adding special decorations (dllimport/dllexport), which let the
+compiler produce specific assembler instructions to deal with this
+issue. This increases the effort necessary to port existing Un*x
+code to these platforms, especially for large
+c++ libraries and applications. The auto-import feature, which was
+initially provided by Paul Sokolovsky, allows one to omit the
+decorations to achieve a behavior that conforms to that on POSIX/Un*x
+platforms. This feature is enabled with the @samp{--enable-auto-import}
+command-line option, although it is enabled by default on cygwin/mingw.
+The @samp{--enable-auto-import} option itself now serves mainly to
+suppress any warnings that are ordinarily emitted when linked objects
+trigger the feature's use.
+
+auto-import of variables does not always work flawlessly without
+additional assistance. Sometimes, you will see this message
+
+"variable '<var>' can't be auto-imported. Please read the
+documentation for ld's @code{--enable-auto-import} for details."
+
+The @samp{--enable-auto-import} documentation explains why this error
+occurs, and several methods that can be used to overcome this difficulty.
+One of these methods is the @emph{runtime pseudo-relocs} feature, described
+below.
+
+@cindex runtime pseudo-relocation
+For complex variables imported from DLLs (such as structs or classes),
+object files typically contain a base address for the variable and an
+offset (@emph{addend}) within the variable--to specify a particular
+field or public member, for instance. Unfortunately, the runtime loader used
+in win32 environments is incapable of fixing these references at runtime
+without the additional information supplied by dllimport/dllexport decorations.
+The standard auto-import feature described above is unable to resolve these
+references.
+
+The @samp{--enable-runtime-pseudo-relocs} switch allows these references to
+be resolved without error, while leaving the task of adjusting the references
+themselves (with their non-zero addends) to specialized code provided by the
+runtime environment. Recent versions of the cygwin and mingw environments and
+compilers provide this runtime support; older versions do not. However, the
+support is only necessary on the developer's platform; the compiled result will
+run without error on an older system.
+
+@samp{--enable-runtime-pseudo-relocs} is not the default; it must be explicitly
+enabled as needed.
+
+@cindex direct linking to a dll
+@item direct linking to a dll
+The cygwin/mingw ports of @command{ld} support the direct linking,
+including data symbols, to a dll without the usage of any import
+libraries. This is much faster and uses much less memory than does the
+traditional import library method, especially when linking large
+libraries or applications. When @command{ld} creates an import lib, each
+function or variable exported from the dll is stored in its own bfd, even
+though a single bfd could contain many exports. The overhead involved in
+storing, loading, and processing so many bfd's is quite large, and explains the
+tremendous time, memory, and storage needed to link against particularly
+large or complex libraries when using import libs.
+
+Linking directly to a dll uses no extra command-line switches other than
+@samp{-L} and @samp{-l}, because @command{ld} already searches for a number
+of names to match each library. All that is needed from the developer's
+perspective is an understanding of this search, in order to force ld to
+select the dll instead of an import library.
+
+
+For instance, when ld is called with the argument @samp{-lxxx} it will attempt
+to find, in the first directory of its search path,
+
+@example
+libxxx.dll.a
+xxx.dll.a
+libxxx.a
+xxx.lib
+cygxxx.dll (*)
+libxxx.dll
+xxx.dll
+@end example
+
+before moving on to the next directory in the search path.
+
+(*) Actually, this is not @samp{cygxxx.dll} but in fact is @samp{<prefix>xxx.dll},
+where @samp{<prefix>} is set by the @command{ld} option
+@samp{--dll-search-prefix=<prefix>}. In the case of cygwin, the standard gcc spec
+file includes @samp{--dll-search-prefix=cyg}, so in effect we actually search for
+@samp{cygxxx.dll}.
+
+Other win32-based unix environments, such as mingw or pw32, may use other
+@samp{<prefix>}es, although at present only cygwin makes use of this feature. It
+was originally intended to help avoid name conflicts among dll's built for the
+various win32/un*x environments, so that (for example) two versions of a zlib dll
+could coexist on the same machine.
+
+The generic cygwin/mingw path layout uses a @samp{bin} directory for
+applications and dll's and a @samp{lib} directory for the import
+libraries (using cygwin nomenclature):
+
+@example
+bin/
+ cygxxx.dll
+lib/
+ libxxx.dll.a (in case of dll's)
+ libxxx.a (in case of static archive)
+@end example
+
+Linking directly to a dll without using the import library can be
+done two ways:
+
+1. Use the dll directly by adding the @samp{bin} path to the link line
+@example
+gcc -Wl,-verbose -o a.exe -L../bin/ -lxxx
+@end example
+
+However, as the dll's often have version numbers appended to their names
+(@samp{cygncurses-5.dll}) this will often fail, unless one specifies
+@samp{-L../bin -lncurses-5} to include the version. Import libs are generally
+not versioned, and do not have this difficulty.
+
+2. Create a symbolic link from the dll to a file in the @samp{lib}
+directory according to the above mentioned search pattern. This
+should be used to avoid unwanted changes in the tools needed for
+making the app/dll.
+
+@example
+ln -s bin/cygxxx.dll lib/[cyg|lib|]xxx.dll[.a]
+@end example
+
+Then you can link without any make environment changes.
+
+@example
+gcc -Wl,-verbose -o a.exe -L../lib/ -lxxx
+@end example
+
+This technique also avoids the version number problems, because the following is
+perfectly legal
+
+@example
+bin/
+ cygxxx-5.dll
+lib/
+ libxxx.dll.a -> ../bin/cygxxx-5.dll
+@end example
+
+Linking directly to a dll without using an import lib will work
+even when auto-import features are exercised, and even when
+@samp{--enable-runtime-pseudo-relocs} is used.
+
+Given the improvements in speed and memory usage, one might justifiably
+wonder why import libraries are used at all. There are three reasons:
+
+1. Until recently, the link-directly-to-dll functionality did @emph{not}
+work with auto-imported data.
+
+2. Sometimes it is necessary to include pure static objects within the
+import library (which otherwise contains only bfd's for indirection
+symbols that point to the exports of a dll). Again, the import lib
+for the cygwin kernel makes use of this ability, and it is not
+possible to do this without an import lib.
+
+3. Symbol aliases can only be resolved using an import lib. This is
+critical when linking against OS-supplied dll's (eg, the win32 API)
+in which symbols are usually exported as undecorated aliases of their
+stdcall-decorated assembly names.
+
+So, import libs are not going away. But the ability to replace
+true import libs with a simple symbolic link to (or a copy of)
+a dll, in many cases, is a useful addition to the suite of tools
+binutils makes available to the win32 developer. Given the
+massive improvements in memory requirements during linking, storage
+requirements, and linking speed, we expect that many developers
+will soon begin to use this feature whenever possible.
+
+@item symbol aliasing
+@table @emph
+@item adding additional names
+Sometimes, it is useful to export symbols with additional names.
+A symbol @samp{foo} will be exported as @samp{foo}, but it can also be
+exported as @samp{_foo} by using special directives in the DEF file
+when creating the dll. This will affect also the optional created
+import library. Consider the following DEF file:
+
+@example
+LIBRARY "xyz.dll" BASE=0x61000000
+
+EXPORTS
+foo
+_foo = foo
+@end example
+
+The line @samp{_foo = foo} maps the symbol @samp{foo} to @samp{_foo}.
+
+Another method for creating a symbol alias is to create it in the
+source code using the "weak" attribute:
+
+@example
+void foo () @{ /* Do something. */; @}
+void _foo () __attribute__ ((weak, alias ("foo")));
+@end example
+
+See the gcc manual for more information about attributes and weak
+symbols.
+
+@item renaming symbols
+Sometimes it is useful to rename exports. For instance, the cygwin
+kernel does this regularly. A symbol @samp{_foo} can be exported as
+@samp{foo} but not as @samp{_foo} by using special directives in the
+DEF file. (This will also affect the import library, if it is
+created). In the following example:
+
+@example
+LIBRARY "xyz.dll" BASE=0x61000000
+
+EXPORTS
+_foo = foo
+@end example
+
+The line @samp{_foo = foo} maps the exported symbol @samp{foo} to
+@samp{_foo}.
+@end table
+
+Note: using a DEF file disables the default auto-export behavior,
+unless the @samp{--export-all-symbols} command line option is used.
+If, however, you are trying to rename symbols, then you should list
+@emph{all} desired exports in the DEF file, including the symbols
+that are not being renamed, and do @emph{not} use the
+@samp{--export-all-symbols} option. If you list only the
+renamed symbols in the DEF file, and use @samp{--export-all-symbols}
+to handle the other symbols, then the both the new names @emph{and}
+the original names for the renamed symbols will be exported.
+In effect, you'd be aliasing those symbols, not renaming them,
+which is probably not what you wanted.
+
+@cindex weak externals
+@item weak externals
+The Windows object format, PE, specifies a form of weak symbols called
+weak externals. When a weak symbol is linked and the symbol is not
+defined, the weak symbol becomes an alias for some other symbol. There
+are three variants of weak externals:
+@itemize
+@item Definition is searched for in objects and libraries, historically
+called lazy externals.
+@item Definition is searched for only in other objects, not in libraries.
+This form is not presently implemented.
+@item No search; the symbol is an alias. This form is not presently
+implemented.
+@end itemize
+As a GNU extension, weak symbols that do not specify an alternate symbol
+are supported. If the symbol is undefined when linking, the symbol
+uses a default value.
+@end table
+
+@ifclear GENERIC
+@lowersections
+@end ifclear
@end ifset
+@ifset XTENSA
+@ifclear GENERIC
+@raisesections
+@end ifclear
+
+@node Xtensa
+@section @code{ld} and Xtensa Processors
+
+@cindex Xtensa processors
+The default @command{ld} behavior for Xtensa processors is to interpret
+@code{SECTIONS} commands so that lists of explicitly named sections in a
+specification with a wildcard file will be interleaved when necessary to
+keep literal pools within the range of PC-relative load offsets. For
+example, with the command:
+
+@smallexample
+SECTIONS
+@{
+ .text : @{
+ *(.literal .text)
+ @}
+@}
+@end smallexample
+
+@noindent
+@command{ld} may interleave some of the @code{.literal}
+and @code{.text} sections from different object files to ensure that the
+literal pools are within the range of PC-relative load offsets. A valid
+interleaving might place the @code{.literal} sections from an initial
+group of files followed by the @code{.text} sections of that group of
+files. Then, the @code{.literal} sections from the rest of the files
+and the @code{.text} sections from the rest of the files would follow.
+
+@cindex @option{--relax} on Xtensa
+@cindex relaxing on Xtensa
+Relaxation is enabled by default for the Xtensa version of @command{ld} and
+provides two important link-time optimizations. The first optimization
+is to combine identical literal values to reduce code size. A redundant
+literal will be removed and all the @code{L32R} instructions that use it
+will be changed to reference an identical literal, as long as the
+location of the replacement literal is within the offset range of all
+the @code{L32R} instructions. The second optimization is to remove
+unnecessary overhead from assembler-generated ``longcall'' sequences of
+@code{L32R}/@code{CALLX@var{n}} when the target functions are within
+range of direct @code{CALL@var{n}} instructions.
+
+For each of these cases where an indirect call sequence can be optimized
+to a direct call, the linker will change the @code{CALLX@var{n}}
+instruction to a @code{CALL@var{n}} instruction, remove the @code{L32R}
+instruction, and remove the literal referenced by the @code{L32R}
+instruction if it is not used for anything else. Removing the
+@code{L32R} instruction always reduces code size but can potentially
+hurt performance by changing the alignment of subsequent branch targets.
+By default, the linker will always preserve alignments, either by
+switching some instructions between 24-bit encodings and the equivalent
+density instructions or by inserting a no-op in place of the @code{L32R}
+instruction that was removed. If code size is more important than
+performance, the @option{--size-opt} option can be used to prevent the
+linker from widening density instructions or inserting no-ops, except in
+a few cases where no-ops are required for correctness.
+
+The following Xtensa-specific command-line options can be used to
+control the linker:
+
+@cindex Xtensa options
+@table @option
+@kindex --no-relax
+@item --no-relax
+Since the Xtensa version of @code{ld} enables the @option{--relax} option
+by default, the @option{--no-relax} option is provided to disable
+relaxation.
+
+@item --size-opt
+When optimizing indirect calls to direct calls, optimize for code size
+more than performance. With this option, the linker will not insert
+no-ops or widen density instructions to preserve branch target
+alignment. There may still be some cases where no-ops are required to
+preserve the correctness of the code.
+@end table
+
@ifclear GENERIC
@lowersections
@end ifclear
+@end ifset
@ifclear SingleFormat
@node BFD
@end menu
@node BFD outline
-@section How it works: an outline of BFD
+@section How It Works: An Outline of BFD
@cindex opening object files
@include bfdsumm.texi
@end ifclear
@node Reporting Bugs
@chapter Reporting Bugs
-@cindex bugs in @code{ld}
-@cindex reporting bugs in @code{ld}
+@cindex bugs in @command{ld}
+@cindex reporting bugs in @command{ld}
-Your bug reports play an essential role in making @code{ld} reliable.
+Your bug reports play an essential role in making @command{ld} 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 @code{ld}
+to help the entire community by making the next version of @command{ld}
work better. Bug reports are your contribution to the maintenance of
-@code{ld}.
+@command{ld}.
In order for a bug report to serve its purpose, you must include the
information that enables us to fix the bug.
@end menu
@node Bug Criteria
-@section Have you found a bug?
+@section Have You Found a Bug?
@cindex bug criteria
If you are not sure whether you have found a bug, here are some guidelines:
@cindex crash of linker
@item
If the linker gets a fatal signal, for any input whatever, that is a
-@code{ld} bug. Reliable linkers never crash.
+@command{ld} bug. Reliable linkers never crash.
@cindex error on valid input
@item
-If @code{ld} produces an error message for valid input, that is a bug.
+If @command{ld} produces an error message for valid input, that is a bug.
@cindex invalid input
@item
-If @code{ld} does not produce an error message for invalid input, that
+If @command{ld} does not produce an error message for invalid input, that
may be a bug. In the general case, the linker can not verify that
object files are correct.
@item
If you are an experienced user of linkers, your suggestions for
-improvement of @code{ld} are welcome in any case.
+improvement of @command{ld} are welcome in any case.
@end itemize
@node Bug Reporting
-@section How to report bugs
+@section How to Report Bugs
@cindex bug reports
-@cindex @code{ld} bugs, reporting
+@cindex @command{ld} bugs, reporting
A number of companies and individuals offer support for @sc{gnu}
-products. If you obtained @code{ld} from a support organization, we
+products. If you obtained @command{ld} 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.
-Otherwise, send bug reports for @code{ld} to
-@samp{bug-binutils@@gnu.org}.
+@ifset BUGURL
+Otherwise, send bug reports for @command{ld} to
+@value{BUGURL}.
+@end ifset
The fundamental principle of reporting bugs usefully is this:
@strong{report all the facts}. If you are not sure whether to state a
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 symbol you use in an example does not matter.
-Well, probably it does not, but one cannot be sure. Perhaps the bug is
-a stray memory reference which happens to fetch from the location where
-that name is stored in memory; perhaps, if the name were different, the
-contents of that location would fool the linker 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.
+assume that the name of a symbol you use in an example does not
+matter. Well, probably it does not, but one cannot be sure. Perhaps
+the bug is a stray memory reference which happens to fetch from the
+location where that name is stored in memory; perhaps, if the name
+were different, the contents of that location would fool the linker
+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.
+bell?'' This cannot help us fix a bug, so it is basically useless. We
+respond by asking for enough details to enable us to investigate.
+You might as well expedite matters by sending them to begin with.
To enable us to fix the bug, you should include all these things:
@itemize @bullet
@item
-The version of @code{ld}. @code{ld} announces it if you start it with
+The version of @command{ld}. @command{ld} 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 @code{ld}.
+the bug in the current version of @command{ld}.
@item
-Any patches you may have applied to the @code{ld} source, including any
+Any patches you may have applied to the @command{ld} source, including any
patches made to the @code{BFD} library.
@item
version number.
@item
-What compiler (and its version) was used to compile @code{ld}---e.g.
+What compiler (and its version) was used to compile @command{ld}---e.g.
``@code{gcc-2.7}''.
@item
@item
A complete input file, or set of input files, that will reproduce the
-bug. 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.
+bug. It is generally most helpful to send the actual object files
+provided that they are reasonably small. Say no more than 10K. For
+bigger files you can either make them available by FTP or HTTP or else
+state that you are willing to send the object file(s) to whomever
+requests them. (Note - your email will be going to a mailing list, so
+we do not want to clog it up with large attachments). But small
+attachments are best.
If the source files were assembled using @code{gas} or compiled using
@code{gcc}, then it may be OK to send the source files rather than the
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 @code{ld} gets a fatal signal, then we
+Of course, if the bug is that @command{ld} 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 @code{ld} is out of synch, or you have encountered a bug in the
+copy of @command{ld} is out of sync, 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
any conclusion from our observations.
@item
-If you wish to suggest changes to the @code{ld} source, send us context
+If you wish to suggest changes to the @command{ld} 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
+If you even discuss something in the @command{ld} source, refer to it by
context, not by line number.
The line numbers in our development sources will not match those in your
a patch is all we need. We might see problems with your patch and decide
to fix the problem another way, or we might not understand it at all.
-Sometimes with a program as complicated as @code{ld} it is very hard to
+Sometimes with a program as complicated as @command{ld} 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
@node MRI
@appendix MRI Compatible Script Files
@cindex MRI compatibility
-To aid users making the transition to @sc{gnu} @code{ld} from the MRI
-linker, @code{ld} can use MRI compatible linker scripts as an
+To aid users making the transition to @sc{gnu} @command{ld} from the MRI
+linker, @command{ld} can use MRI compatible linker scripts as an
alternative to the more general-purpose linker scripting language
described in @ref{Scripts}. MRI compatible linker scripts have a much
simpler command set than the scripting language otherwise used with
-@code{ld}. @sc{gnu} @code{ld} supports the most commonly used MRI
+@command{ld}. @sc{gnu} @command{ld} supports the most commonly used MRI
linker commands; these commands are described here.
In general, MRI scripts aren't of much use with the @code{a.out} object
Each command in an MRI-compatible script occupies its own line; each
command line starts with the keyword that identifies the command (though
blank lines are also allowed for punctuation). If a line of an
-MRI-compatible script begins with an unrecognized keyword, @code{ld}
+MRI-compatible script begins with an unrecognized keyword, @command{ld}
issues a warning message, but continues processing the script.
Lines beginning with @samp{*} are comments.
@cindex @code{ABSOLUTE} (MRI)
@item ABSOLUTE @var{secname}
@itemx ABSOLUTE @var{secname}, @var{secname}, @dots{} @var{secname}
-Normally, @code{ld} includes in the output file all sections from all
+Normally, @command{ld} includes in the output file all sections from all
the input files. However, in an MRI-compatible script, you can use the
@code{ABSOLUTE} command to restrict the sections that will be present in
your output program. If the @code{ABSOLUTE} command is used at all in a
@cindex @code{LIST} (MRI)
@item LIST @var{anything}@dots{}
Print (to the standard output file) a link map, as produced by the
-@code{ld} command-line option @samp{-M}.
+@command{ld} command-line option @samp{-M}.
The keyword @code{LIST} may be followed by anything on the
same line, with no change in its effect.
@item LOAD @var{filename}
@itemx LOAD @var{filename}, @var{filename}, @dots{} @var{filename}
Include one or more object file @var{filename} in the link; this has the
-same effect as specifying @var{filename} directly on the @code{ld}
+same effect as specifying @var{filename} directly on the @command{ld}
command line.
@cindex @code{NAME} (MRI)
@item NAME @var{output-name}
-@var{output-name} is the name for the program produced by @code{ld}; the
+@var{output-name} is the name for the program produced by @command{ld}; the
MRI-compatible command @code{NAME} is equivalent to the command-line
option @samp{-o} or the general script language command @code{OUTPUT}.
@cindex @code{ORDER} (MRI)
@item ORDER @var{secname}, @var{secname}, @dots{} @var{secname}
@itemx ORDER @var{secname} @var{secname} @var{secname}
-Normally, @code{ld} orders the sections in its output file in the
+Normally, @command{ld} orders the sections in its output file in the
order in which they first appear in the input files. In an MRI-compatible
script, you can override this ordering with the @code{ORDER} command. The
sections you list with @code{ORDER} will appear first in your output
@node GNU Free Documentation License
@appendix GNU Free Documentation License
-@cindex GNU Free Documentation License
-
- GNU Free Documentation License
-
- Version 1.1, March 2000
-
- Copyright (C) 2000 Free Software Foundation, Inc.
- 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
-
- Everyone is permitted to copy and distribute verbatim copies
- of this license document, but changing it is not allowed.
-
-
-0. PREAMBLE
-
-The purpose of this License is to make a manual, textbook, or other
-written document "free" in the sense of freedom: to assure everyone
-the effective freedom to copy and redistribute it, with or without
-modifying it, either commercially or noncommercially. Secondarily,
-this License preserves for the author and publisher a way to get
-credit for their work, while not being considered responsible for
-modifications made by others.
-
-This License is a kind of "copyleft", which means that derivative
-works of the document must themselves be free in the same sense. It
-complements the GNU General Public License, which is a copyleft
-license designed for free software.
-
-We have designed this License in order to use it for manuals for free
-software, because free software needs free documentation: a free
-program should come with manuals providing the same freedoms that the
-software does. But this License is not limited to software manuals;
-it can be used for any textual work, regardless of subject matter or
-whether it is published as a printed book. We recommend this License
-principally for works whose purpose is instruction or reference.
-
-
-1. APPLICABILITY AND DEFINITIONS
-
-This License applies to any manual or other work that contains a
-notice placed by the copyright holder saying it can be distributed
-under the terms of this License. The "Document", below, refers to any
-such manual or work. Any member of the public is a licensee, and is
-addressed as "you".
-
-A "Modified Version" of the Document means any work containing the
-Document or a portion of it, either copied verbatim, or with
-modifications and/or translated into another language.
-
-A "Secondary Section" is a named appendix or a front-matter section of
-the Document that deals exclusively with the relationship of the
-publishers or authors of the Document to the Document's overall subject
-(or to related matters) and contains nothing that could fall directly
-within that overall subject. (For example, if the Document is in part a
-textbook of mathematics, a Secondary Section may not explain any
-mathematics.) The relationship could be a matter of historical
-connection with the subject or with related matters, or of legal,
-commercial, philosophical, ethical or political position regarding
-them.
-
-The "Invariant Sections" are certain Secondary Sections whose titles
-are designated, as being those of Invariant Sections, in the notice
-that says that the Document is released under this License.
-
-The "Cover Texts" are certain short passages of text that are listed,
-as Front-Cover Texts or Back-Cover Texts, in the notice that says that
-the Document is released under this License.
-
-A "Transparent" copy of the Document means a machine-readable copy,
-represented in a format whose specification is available to the
-general public, whose contents can be viewed and edited directly and
-straightforwardly with generic text editors or (for images composed of
-pixels) generic paint programs or (for drawings) some widely available
-drawing editor, and that is suitable for input to text formatters or
-for automatic translation to a variety of formats suitable for input
-to text formatters. A copy made in an otherwise Transparent file
-format whose markup has been designed to thwart or discourage
-subsequent modification by readers is not Transparent. A copy that is
-not "Transparent" is called "Opaque".
-
-Examples of suitable formats for Transparent copies include plain
-ASCII without markup, Texinfo input format, LaTeX input format, SGML
-or XML using a publicly available DTD, and standard-conforming simple
-HTML designed for human modification. Opaque formats include
-PostScript, PDF, proprietary formats that can be read and edited only
-by proprietary word processors, SGML or XML for which the DTD and/or
-processing tools are not generally available, and the
-machine-generated HTML produced by some word processors for output
-purposes only.
-
-The "Title Page" means, for a printed book, the title page itself,
-plus such following pages as are needed to hold, legibly, the material
-this License requires to appear in the title page. For works in
-formats which do not have any title page as such, "Title Page" means
-the text near the most prominent appearance of the work's title,
-preceding the beginning of the body of the text.
-
-
-2. VERBATIM COPYING
-
-You may copy and distribute the Document in any medium, either
-commercially or noncommercially, provided that this License, the
-copyright notices, and the license notice saying this License applies
-to the Document are reproduced in all copies, and that you add no other
-conditions whatsoever to those of this License. You may not use
-technical measures to obstruct or control the reading or further
-copying of the copies you make or distribute. However, you may accept
-compensation in exchange for copies. If you distribute a large enough
-number of copies you must also follow the conditions in section 3.
-
-You may also lend copies, under the same conditions stated above, and
-you may publicly display copies.
-
-
-3. COPYING IN QUANTITY
-
-If you publish printed copies of the Document numbering more than 100,
-and the Document's license notice requires Cover Texts, you must enclose
-the copies in covers that carry, clearly and legibly, all these Cover
-Texts: Front-Cover Texts on the front cover, and Back-Cover Texts on
-the back cover. Both covers must also clearly and legibly identify
-you as the publisher of these copies. The front cover must present
-the full title with all words of the title equally prominent and
-visible. You may add other material on the covers in addition.
-Copying with changes limited to the covers, as long as they preserve
-the title of the Document and satisfy these conditions, can be treated
-as verbatim copying in other respects.
-
-If the required texts for either cover are too voluminous to fit
-legibly, you should put the first ones listed (as many as fit
-reasonably) on the actual cover, and continue the rest onto adjacent
-pages.
-
-If you publish or distribute Opaque copies of the Document numbering
-more than 100, you must either include a machine-readable Transparent
-copy along with each Opaque copy, or state in or with each Opaque copy
-a publicly-accessible computer-network location containing a complete
-Transparent copy of the Document, free of added material, which the
-general network-using public has access to download anonymously at no
-charge using public-standard network protocols. If you use the latter
-option, you must take reasonably prudent steps, when you begin
-distribution of Opaque copies in quantity, to ensure that this
-Transparent copy will remain thus accessible at the stated location
-until at least one year after the last time you distribute an Opaque
-copy (directly or through your agents or retailers) of that edition to
-the public.
-
-It is requested, but not required, that you contact the authors of the
-Document well before redistributing any large number of copies, to give
-them a chance to provide you with an updated version of the Document.
-
-
-4. MODIFICATIONS
-
-You may copy and distribute a Modified Version of the Document under
-the conditions of sections 2 and 3 above, provided that you release
-the Modified Version under precisely this License, with the Modified
-Version filling the role of the Document, thus licensing distribution
-and modification of the Modified Version to whoever possesses a copy
-of it. In addition, you must do these things in the Modified Version:
-
-A. Use in the Title Page (and on the covers, if any) a title distinct
- from that of the Document, and from those of previous versions
- (which should, if there were any, be listed in the History section
- of the Document). You may use the same title as a previous version
- if the original publisher of that version gives permission.
-B. List on the Title Page, as authors, one or more persons or entities
- responsible for authorship of the modifications in the Modified
- Version, together with at least five of the principal authors of the
- Document (all of its principal authors, if it has less than five).
-C. State on the Title page the name of the publisher of the
- Modified Version, as the publisher.
-D. Preserve all the copyright notices of the Document.
-E. Add an appropriate copyright notice for your modifications
- adjacent to the other copyright notices.
-F. Include, immediately after the copyright notices, a license notice
- giving the public permission to use the Modified Version under the
- terms of this License, in the form shown in the Addendum below.
-G. Preserve in that license notice the full lists of Invariant Sections
- and required Cover Texts given in the Document's license notice.
-H. Include an unaltered copy of this License.
-I. Preserve the section entitled "History", and its title, and add to
- it an item stating at least the title, year, new authors, and
- publisher of the Modified Version as given on the Title Page. If
- there is no section entitled "History" in the Document, create one
- stating the title, year, authors, and publisher of the Document as
- given on its Title Page, then add an item describing the Modified
- Version as stated in the previous sentence.
-J. Preserve the network location, if any, given in the Document for
- public access to a Transparent copy of the Document, and likewise
- the network locations given in the Document for previous versions
- it was based on. These may be placed in the "History" section.
- You may omit a network location for a work that was published at
- least four years before the Document itself, or if the original
- publisher of the version it refers to gives permission.
-K. In any section entitled "Acknowledgements" or "Dedications",
- preserve the section's title, and preserve in the section all the
- substance and tone of each of the contributor acknowledgements
- and/or dedications given therein.
-L. Preserve all the Invariant Sections of the Document,
- unaltered in their text and in their titles. Section numbers
- or the equivalent are not considered part of the section titles.
-M. Delete any section entitled "Endorsements". Such a section
- may not be included in the Modified Version.
-N. Do not retitle any existing section as "Endorsements"
- or to conflict in title with any Invariant Section.
-
-If the Modified Version includes new front-matter sections or
-appendices that qualify as Secondary Sections and contain no material
-copied from the Document, you may at your option designate some or all
-of these sections as invariant. To do this, add their titles to the
-list of Invariant Sections in the Modified Version's license notice.
-These titles must be distinct from any other section titles.
-
-You may add a section entitled "Endorsements", provided it contains
-nothing but endorsements of your Modified Version by various
-parties--for example, statements of peer review or that the text has
-been approved by an organization as the authoritative definition of a
-standard.
-
-You may add a passage of up to five words as a Front-Cover Text, and a
-passage of up to 25 words as a Back-Cover Text, to the end of the list
-of Cover Texts in the Modified Version. Only one passage of
-Front-Cover Text and one of Back-Cover Text may be added by (or
-through arrangements made by) any one entity. If the Document already
-includes a cover text for the same cover, previously added by you or
-by arrangement made by the same entity you are acting on behalf of,
-you may not add another; but you may replace the old one, on explicit
-permission from the previous publisher that added the old one.
-
-The author(s) and publisher(s) of the Document do not by this License
-give permission to use their names for publicity for or to assert or
-imply endorsement of any Modified Version.
-
-
-5. COMBINING DOCUMENTS
-
-You may combine the Document with other documents released under this
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-ADDENDUM: How to use this License for your documents
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+@include fdl.texi
-@smallexample
- Copyright (c) YEAR YOUR NAME.
- Permission is granted to copy, distribute and/or modify this document
- under the terms of the GNU Free Documentation License, Version 1.1
- or any later version published by the Free Software Foundation;
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-@end smallexample
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-
-@node Index
-@unnumbered Index
+@node LD Index
+@unnumbered LD Index
@printindex cp
% Blame: doc@cygnus.com, 28mar91.
@end tex
-
-@contents
@bye
projects / deliverable / binutils-gdb.git / blobdiff