@ifinfo
This file documents the @sc{gnu} linker LD.
-Copyright (C) 1991, 92, 93, 94, 95, 1996 Free Software Foundation, Inc.
+Copyright (C) 1991, 92, 93, 94, 95, 96, 97, 1998 Free Software Foundation, Inc.
Permission is granted to make and distribute verbatim copies of
this manual provided the copyright notice and this permission notice
@end tex
@vskip 0pt plus 1filll
-Copyright @copyright{} 1991, 92, 93, 94, 95, 1996 Free Software Foundation, Inc.
+Copyright @copyright{} 1991, 92, 93, 94, 95, 96, 97, 1998 Free Software Foundation, Inc.
Permission is granted to make and distribute verbatim copies of
this manual provided the copyright notice and this permission notice
@end ifclear
@c Following blank line required for remaining bug in makeinfo conds/menus
+* Reporting Bugs:: Reporting Bugs
* MRI:: MRI Compatible Script Files
* Index:: Index
@end menu
@cindex command line
@cindex options
-Here is a summary of the options you can use on the @code{ld} command
-line:
-
-@c FIXME! -relax only avail h8/300, i960. Conditionals screwed in examples.
-@smallexample
-ld [ -o @var{output} ] @var{objfile}@dots{}
- [ -A@var{architecture} ] [ -b @var{input-format} ]
- [ -Bstatic ] [ -Bdynamic ] [ -Bsymbolic ]
- [ -c @var{MRI-commandfile} ] [ -d | -dc | -dp ]
- [ -defsym @var{symbol}=@var{expression} ]
- [ -dynamic-linker @var{file} ] [ -embedded-relocs ] [ -export-dynamic ]
- [ -e @var{entry} ] [ -F ] [ -F @var{format} ]
- [ -format @var{input-format} ] [ -g ] [ -G @var{size} ]
- [ -help ] [ -i ] [ -l@var{archive} ] [ -L@var{searchdir} ]
- [ -M ] [ -Map @var{mapfile} ] [ -m @var{emulation} ]
- [ -N | -n ] [ -noinhibit-exec ] [ -no-keep-memory ]
- [ -oformat @var{output-format} ] [ -R @var{filename} ]
- [ -relax ] [ -retain-symbols-file @var{filename} ]
- [ -r | -Ur ] [ -rpath @var{dir} ] [-rpath-link @var{dir} ]
- [ -S ] [ -s ] [ -soname @var{name} ] [ -shared ]
- [ -sort-common ] [ -stats ] [ -T @var{commandfile} ]
- [ -Ttext @var{org} ] [ -Tdata @var{org} ]
- [ -Tbss @var{org} ] [ -t ] [ -traditional-format ]
- [ -u @var{symbol}] [-V] [-v] [ -verbose] [ -version ]
- [ -warn-common ] [ -warn-constructors] [ -warn-once ]
- [ -y @var{symbol} ] [ -X ] [-x ]
- [ -( [ archives ] -) ]
- [ --start-group [ archives ] --end-group ]
- [ -split-by-reloc @var{count} ] [ -split-by-file ]
- [ --whole-archive ] [ --no-whole-archive ]
-@end smallexample
-
-This plethora of command-line options may seem intimidating, but in
-actual practice few of them are used in any particular context.
+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
object files on a standard, supported Unix system. On such a system, to
directories. (See the discussion of the @samp{-l} option below.)
The command-line options to @code{ld} may be specified in any order, and
-may be repeated at will. Repeating most options with a
-different argument will either have no further effect, or override prior
+may be repeated at will. Repeating most options with a different
+argument will either have no further effect, or override prior
occurrences (those further to the left on the command line) of that
-option.
-
-@ifclear SingleFormat
-The exceptions---which may meaningfully be used more than once---are
-@samp{-A}, @samp{-b} (or its synonym @samp{-format}), @samp{-defsym},
-@samp{-L}, @samp{-l}, @samp{-R}, @samp{-u}, and @samp{-(} (or its
-synonym @samp{--start-group})..
-@end ifclear
-@ifset SingleFormat
-The exceptions---which may meaningfully be used more than once---are
-@samp{-A}, @samp{-defsym}, @samp{-L}, @samp{-l}, @samp{-R}, @samp{-u},
-and @samp{-(} (or its synonym @samp{--start-group}).
-@end ifset
+option. Options which may be meaningfully specified more than once are
+noted in the descriptions below.
@cindex object files
-The list of object files to be linked together, shown as @var{objfile}@dots{},
-may follow, precede, or be mixed in with command-line options, except that
-an @var{objfile} argument may not be placed between an option and
-its argument.
+Non-option arguments are objects files which are to be linked together.
+They may follow, precede, or be mixed in with command-line options,
+except that an object file argument may not be placed between an option
+and its argument.
Usually the linker is invoked with at least one object file, but you can
specify other forms of binary input files using @samp{-l}, @samp{-R},
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. @xref{Commands}.
+@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{Commands}.
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{--oformat} and
-@samp{-oformat} are equivalent. Arguments to multiple-letter options
+@samp{--oformat} are equivalent. Arguments to multiple-letter options
must either be separated from the option name by an equals sign, or be
given as separate arguments immediately following the option that
requires them. For example, @samp{--oformat srec} and
of multiple-letter options are accepted.
@table @code
+@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
+@samp{-Bstatic}, and the other two keywords are functionally equivalent
+to @samp{-Bdynamic}. This option may be used any number of times.
+
@ifset I960
@cindex architectures
@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
@var{architecture} argument identifies the particular architecture in
@ifclear SingleFormat
@cindex binary input format
@kindex -b @var{format}
+@kindex --format=@var{format}
@cindex input format
@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
@samp{-b} option to specify the binary format for input object files
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
-formats with @samp{objdump -i}.) @w{@samp{-format @var{input-format}}}
-has the same effect, as does the script command @code{TARGET}.
+formats with @samp{objdump -i}.)
@xref{BFD}.
You may want to use this option if you are linking files with an unusual
Commands}.
@end ifclear
-@kindex -Bstatic
-@item -Bstatic
-Do not link against shared libraries. This is only meaningful on
-platforms for which shared libraries are supported.
-
-@kindex -Bdynamic
-@item -Bdynamic
-Link against dynamic libraries. This is only meaningful on platforms
-for which shared libraries are supported. This option is normally the
-default on such platforms.
-
-@kindex -Bsymbolic
-@item -Bsymbolic
-When creating a shared library, bind references to global symbols to the
-definition within the shared library, if any. Normally, it is possible
-for a program linked against a shared library to override the definition
-within the shared library. This option is only meaningful on ELF
-platforms which support shared libraries.
-
@kindex -c @var{MRI-cmdfile}
+@kindex --mri-script=@var{MRI-cmdfile}
@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
files written in an alternate, restricted command language, described in
@ref{MRI,,MRI Compatible Script Files}. Introduce MRI script files with
@code{FORCE_COMMON_ALLOCATION} has the same effect. @xref{Option
Commands}.
-@cindex symbols, from command line
-@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
-limited form of arithmetic is supported for the @var{expression} in this
-context: you may give a hexadecimal constant or the name of an existing
-symbol, or use @code{+} and @code{-} to add or subtract hexadecimal
-constants or symbols. If you need more elaborate expressions, consider
-using the linker command language from a script (@pxref{Assignment, ,
-Assignment: Symbol Definitions}). @emph{Note:} there should be no
-white space between @var{symbol}, the equals sign (``@key{=}''), and
-@var{expression}.
-
-@ifset GENERIC
-@cindex dynamic linker, from command line
-@kindex -dynamic-linker @var{file}
-@item -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.
-@end ifset
-
-@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.
-
@cindex entry point, from command line
@kindex -e @var{entry}
+@kindex --entry=@var{entry}
@item -e @var{entry}
+@itemx --entry=@var{entry}
Use @var{entry} as the explicit symbol for beginning execution of your
program, rather than the default entry point. @xref{Entry Point}, for a
discussion of defaults and other ways of specifying the
entry point.
@cindex dynamic symbol table
-@kindex -export-dynamic
-@item -export-dynamic
-When creating an ELF file, add all symbols to the dynamic symbol table.
-Normally, the dynamic symbol table contains only symbols which are used
-by a dynamic object. This option is needed for some uses of
-@code{dlopen}.
+@kindex -E
+@kindex --export-dynamic
+@item -E
+@itemx --export-dynamic
+When creating a dynamically linked executable, add all symbols to the
+dynamic symbol table. The dynamic symbol table is the set of symbols
+which are visible from dynamic objects at run time.
+
+If you do not use this option, the dynamic symbol table will normally
+contain only those symbols which are referenced by some dynamic object
+mentioned in the link.
+
+If you use @code{dlopen} to load a dynamic object which needs to refer
+back to the symbols defined by the program, rather than some other
+dynamic object, then you will probably need to use this option when
+linking the program itself.
+
+@kindex -f
+@kindex --auxiliary
+@item -f
+@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
+symbol table of the shared object @var{name}.
+
+If you later link a program against this filter object, then, when you
+run the program, the dynamic linker will see the DT_AUXILIARY field. If
+the dynamic linker resolves any symbols from the filter object, it will
+first check whether there is a definition in the shared object
+@var{name}. If there is one, it will be used instead of the definition
+in the filter object. The shared object @var{name} need not exist.
+Thus the shared object @var{name} may be used to provide an alternative
+implementation of certain functions, perhaps for debugging or for
+machine specific performance.
+
+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.
-@ifclear SingleFormat
@kindex -F
-@item -F
-@itemx -F@var{format}
-Ignored. Some older linkers used this option throughout a compilation
+@kindex --filter
+@item -F @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
+on the symbol table of the shared object @var{name}.
+
+If you later link a program against this filter object, then, when you
+run the program, the dynamic linker will see the DT_FILTER field. The
+dynamic linker will resolve symbols according to the symbol table of the
+filter object as usual, but it will actually link to the definitions
+found in the shared object @var{name}. Thus the filter object can be
+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
toolchain for specifying object-file format for both input and output
-object files. The mechanisms @code{ld} uses for this purpose (the
-@samp{-b} or @samp{-format} options for input files, @samp{-oformat}
-option or the @code{TARGET} command in linker scripts for output files,
-the @code{GNUTARGET} environment variable) are more flexible, but
-@code{ld} accepts the @samp{-F} option for compatibility with scripts
-written to call the old linker.
-
-@kindex -format
-@item -format @var{input-format}
-Synonym for @samp{-b @var{input-format}}.
-@end ifclear
+object files. The @sc{gnu} linker uses other mechanisms for this
+purpose: the @code{-b}, @code{--format}, @code{--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.
+
+@kindex --force-exe-suffix
+@item --force-exe-suffix
+Make sure that an output file has a .exe suffix.
+
+If a successfully built fully linked output file does not have a
+@code{.exe} or @code{.dll} suffix, this option forces the linker to copy
+the output file to one of the same name with a @code{.exe} suffix. This
+option is useful when using unmodified Unix makefiles on a Microsoft
+Windows host, since some versions of Windows won't run an image unless
+it ends in a @code{.exe} suffix.
@kindex -g
@item -g
Ignored. Provided for compatibility with other tools.
@kindex -G
+@kindex --gpsize
@cindex object size
@item -G@var{value}
-@itemx -G @var{value}
+@itemx --gpsize=@var{value}
Set the maximum size of objects to be optimized using the GP register to
-@var{size} under MIPS ECOFF. Ignored for other object file formats.
+@var{size}. This is only meaningful for object file formats such as
+MIPS ECOFF which supports putting large and small objects into different
+sections. This is ignored for other object file formats.
-@cindex help
-@cindex usage
-@kindex -help
-@item -help
-Print a summary of the command-line options on the standard output and exit.
+@cindex runtime library name
+@kindex -h@var{name}
+@kindex -soname=@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
+which has a DT_SONAME field, then when the executable is run the dynamic
+linker will attempt to load the shared object specified by the DT_SONAME
+field rather than the using the file name given to the linker.
@kindex -i
@cindex incremental link
@cindex archive files, from cmd line
@kindex -l@var{archive}
-@item -l@var{ar}
-Add archive file @var{archive} to the list of files to link. This
+@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{ar}.a} for every @var{archive}
-specified.
+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.
+
+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
+was undefined in some object which appeared before the archive on the
+command line, the linker will include the appropriate file(s) from the
+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
+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
+behaviour of the AIX linker.
+@end ifset
@cindex search directory, from cmd line
@kindex -L@var{dir}
+@kindex --library-path=@var{dir}
@item -L@var{searchdir}
-@itemx -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
option any number of times. The directories are searched in the order
@code{SEARCH_DIR} command. Directories specified this way are searched
at the point in which the linker script appears in the command line.
+@cindex emulation
+@kindex -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.
+
+If the @samp{-m} option is not used, the emulation is taken from the
+@code{LDEMULATION} environment variable, if that is defined.
+
+Otherwise, the default emulation depends upon how the linker was
+configured.
+
@cindex link map
@kindex -M
-@item -M
+@kindex --print-map
+@item -M
+@itemx --print-map
Print (to the standard output) a link map---diagnostic information about
where symbols are mapped by @code{ld}, and information on global common
storage allocation.
-@cindex link map
-@kindex -Map
-@item -Map @var{mapfile}
-Print to the file @var{mapfile} a link map---diagnostic information
-about where symbols are mapped by @code{ld}, and information on global
-common storage allocation.
-
-@cindex emulation
-@kindex -m @var{emulation}
-@item -m@var{emulation}
-@itemx -m @var{emulation}
-Emulate the @var{emulation} linker. You can list the available
-emulations with the @samp{--verbose} or @samp{-V} options. The default
-depends on how your @code{ld} was configured.
+@kindex -n
+@cindex read-only text
+@cindex NMAGIC
+@kindex --nmagic
+@item -n
+@itemx --nmagic
+Set the text segment to be read only, and mark the output as
+@code{NMAGIC} if possible.
@kindex -N
+@kindex --omagic
@cindex read/write from cmd line
-@kindex OMAGIC
+@cindex OMAGIC
@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}.
-@kindex -n
-@cindex read-only text
-@kindex NMAGIC
-@item -n
-Set the text segment to be read only, and mark the output as
-@code{NMAGIC} if possible.
+@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
+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.
-@cindex output file after errors
-@kindex -noinhibit-exec
-@item -noinhibit-exec
-Retain the executable output file whenever it is still usable.
-Normally, the linker will not produce an output file if it encounters
-errors during the link process; it exits without writing an output file
-when it issues any error whatsoever.
+@cindex partial link
+@cindex relocatable output
+@kindex -r
+@kindex --relocateable
+@item -r
+@itemx --relocateable
+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
+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}.
+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}.
+
+This option does the same thing as @samp{-i}.
+
+@kindex -R @var{file}
+@kindex --just-symbols=@var{file}
+@cindex symbol-only input
+@item -R @var{filename}
+@itemx --just-symbols=@var{filename}
+Read symbol names and their addresses from @var{filename}, but do not
+relocate it or include it in the output. This allows your output file
+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
+followed by a directory name, rather than a file name, it is treated as
+the @code{-rpath} option.
+
+@kindex -s
+@kindex --strip-all
+@cindex strip all symbols
+@item -s
+@itemx --strip-all
+Omit all symbol information from the output file.
+
+@kindex -S
+@kindex --strip-debug
+@cindex strip debugger symbols
+@item -S
+@itemx --strip-debug
+Omit debugger symbol information (but not all symbols) from the output file.
+
+@kindex -t
+@kindex --trace
+@cindex input files, displaying
+@item -t
+@itemx --trace
+Print the names of the input files as @code{ld} processes them.
+
+@kindex -T @var{script}
+@kindex --script=@var{script}
+@cindex script files
+@item -T @var{commandfile}
+@itemx --script=@var{commandfile}
+Read link commands from the file @var{commandfile}. These commands
+replace @code{ld}'s default link script (rather than adding to it), so
+@var{commandfile} must specify everything necessary to describe the
+target format. 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{Commands}. If
+@var{commandfile} does not exist, @code{ld} looks for it in the
+directories specified by any preceding @samp{-L} options. Multiple
+@samp{-T} options accumulate.
+
+@kindex -u @var{symbol}
+@kindex --undefined=@var{symbol}
+@cindex undefined symbol
+@item -u @var{symbol}
+@itemx --undefined=@var{symbol}
+Force @var{symbol} to be entered in the output file as an undefined symbol.
+Doing this may, for example, trigger linking of additional modules from
+standard libraries. @samp{-u} may be repeated with different option
+arguments to enter additional undefined symbols.
+@c Nice idea, but no such command: This option is equivalent
+@c to the @code{EXTERN} linker command.
+
+@kindex -v
+@kindex -V
+@kindex --version
+@cindex version
+@item -v
+@itemx --version
+@itemx -V
+Display the version number for @code{ld}. The @code{-V} option also
+lists the supported emulations.
+
+@kindex -x
+@kindex --discard-all
+@cindex deleting local symbols
+@item -x
+@itemx --discard-all
+Delete all local symbols.
+
+@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}.
+
+@kindex -y @var{symbol}
+@kindex --trace-symbol=@var{symbol}
+@cindex symbol tracing
+@item -y @var{symbol}
+@itemx --trace-symbol=@var{symbol}
+Print the name of each linked file in which @var{symbol} appears. This
+option may be given any number of times. On many systems it is necessary
+to prepend an underscore.
+
+This option is useful when you have an undefined symbol in your link but
+don't know where the reference is coming from.
+
+@kindex -Y @var{path}
+@item -Y @var{path}
+Add @var{path} to the default library search path. This option exists
+for Solaris compatibility.
+
+@kindex -z @var{keyword}
+@item -z @var{keyword}
+This option is ignored for Solaris compatibility.
+
+@kindex -(
+@cindex groups of archives
+@item -( @var{archives} -)
+@itemx --start-group @var{archives} --end-group
+The @var{archives} should be a list of archive files. They may be
+either explicit file names, or @samp{-l} options.
+
+The specified archives are searched repeatedly until no new undefined
+references are created. Normally, an archive is searched only once in
+the order that it is specified on the command line. If a symbol in that
+archive is needed to resolve an undefined symbol referred to by an
+object in an archive that appears later on the command line, the linker
+would not be able to resolve that reference. By grouping the archives,
+they all be searched repeatedly until all possible references are
+resolved.
+
+Using this option has a significant performance cost. It is best to use
+it only when there are unavoidable circular references between two or
+more archives.
+
+@kindex -assert @var{keyword}
+@item -assert @var{keyword}
+This option is ignored for SunOS compatibility.
+
+@kindex -Bdynamic
+@kindex -dy
+@kindex -call_shared
+@item -Bdynamic
+@itemx -dy
+@itemx -call_shared
+Link against dynamic libraries. This is only meaningful on platforms
+for which shared libraries are supported. This option is normally the
+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.
+
+@kindex -Bstatic
+@kindex -dn
+@kindex -non_shared
+@kindex -static
+@item -Bstatic
+@itemx -dn
+@itemx -non_shared
+@itemx -static
+Do not link against shared libraries. This is only meaningful on
+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.
+
+@kindex -Bsymbolic
+@item -Bsymbolic
+When creating a shared library, bind references to global symbols to the
+definition within the shared library, if any. Normally, it is possible
+for a program linked against a shared library to override the definition
+within the shared library. This option is only meaningful on ELF
+platforms which support shared libraries.
+
+@cindex cross reference table
+@kindex --cref
+@item --cref
+Output a cross reference table. If a linker map file is being
+generated, the cross reference table is printed to the map file.
+Otherwise, it is printed on the standard output.
+
+The format of the table is intentionally simple, so that it may be
+easily processed by a script if necessary. The symbols are printed out,
+sorted by name. For each symbol, a list of file names is given. If the
+symbol is defined, the first file listed is the location of the
+definition. The remaining files contain references to the symbol.
+
+@cindex symbols, from command line
+@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
+limited form of arithmetic is supported for the @var{expression} in this
+context: you may give a hexadecimal constant or the name of an existing
+symbol, or use @code{+} and @code{-} to add or subtract hexadecimal
+constants or symbols. If you need more elaborate expressions, consider
+using the linker command language from a script (@pxref{Assignment, ,
+Assignment: Symbol Definitions}). @emph{Note:} there should be no
+white space between @var{symbol}, the equals sign (``@key{=}''), and
+@var{expression}.
+
+@cindex dynamic linker, from command line
+@kindex --dynamic-linker @var{file}
+@item --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 big-endian objects
+@cindex endianness
+@kindex -EB
+@item -EB
+Link big-endian objects. This affects the default output format.
+
+@cindex little-endian objects
+@kindex -EL
+@item -EL
+Link little-endian objects. This affects the default output format.
+
+@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.
+
+@cindex help
+@cindex usage
+@kindex --help
+@item --help
+Print a summary of the command-line options on the standard output and exit.
+
+@cindex link map
+@kindex -Map
+@item -Map @var{mapfile}
+Print to the file @var{mapfile} a link map---diagnostic information
+about where symbols are mapped by @code{ld}, and information on global
+common storage allocation.
@cindex memory usage
-@kindex -no-keep-memory
-@item -no-keep-memory
+@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
instead optimize for memory usage, by rereading the symbol tables as
necessary. This may be required if @code{ld} runs out of memory space
while linking a large executable.
-@kindex -o @var{output}
-@cindex naming the output file
-@item -o @var{output}
-Use @var{output} as the name for the program produced by @code{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 --no-warn-mismatch
+@item --no-warn-mismatch
+Normally @code{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
+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-whole-archive
+@item --no-whole-archive
+Turn off the effect of the @code{--whole-archive} option for subsequent
+archive files.
+
+@cindex output file after errors
+@kindex --noinhibit-exec
+@item --noinhibit-exec
+Retain the executable output file whenever it is still usable.
+Normally, the linker will not produce an output file if it encounters
+errors during the link process; it exits without writing an output file
+when it issues any error whatsoever.
@ifclear SingleFormat
-@kindex -oformat
-@item -oformat @var{output-format}
+@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
-@samp{-oformat} option to specify the binary format for the output
+@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}
should be configured to produce as a default output format the most
this option overrides it. @xref{BFD}.
@end ifclear
-@kindex -R @var{file}
-@cindex symbol-only input
-@item -R @var{filename}
-Read symbol names and their addresses from @var{filename}, but do not
-relocate it or include it in the output. This allows your output file
-to refer symbolically to absolute locations of memory defined in other
-programs.
+@kindex -qmagic
+@item -qmagic
+This option is ignored for Linux compatibility.
-For compatibility with other ELF linkers, if the @code{-R} option is
-followed by a directory name, rather than a file name, it is treated as
-the @code{-rpath} option.
+@kindex -Qy
+@item -Qy
+This option is ignored for SVR4 compatibility.
-@kindex -relax
+@kindex --relax
@cindex synthesizing linker
@cindex relaxing addressing modes
-@item -relax
+@item --relax
An option with machine dependent effects.
@ifset GENERIC
-Currently this option is only supported on the H8/300 and the Intel 960.
+This option is only supported on a few targets.
@end ifset
@ifset H8300
@xref{H8/300,,@code{ld} and the H8/300}.
@xref{i960,, @code{ld} and the Intel 960 family}.
@end ifset
-On some platforms, the @samp{-relax} option performs global optimizations that
-become possible when the linker resolves addressing in the program, such
-as relaxing address modes and synthesizing new instructions in the
-output object file.
+On some platforms, the @samp{--relax} option performs global
+optimizations that become possible when the linker resolves addressing
+in the program, such as relaxing address modes and synthesizing new
+instructions in the output object file.
@ifset GENERIC
-On platforms where this is not supported, @samp{-relax} is accepted, but
-ignored.
+On platforms where this is not supported, @samp{--relax} is accepted,
+but ignored.
@end ifset
@cindex retaining specified symbols
@cindex stripping all but some symbols
@cindex symbols, retaining selectively
-@item -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
where a large global symbol table is accumulated gradually, to conserve
run-time memory.
-@samp{-retain-symbols-file} does @emph{not} discard undefined symbols,
+@samp{--retain-symbols-file} does @emph{not} discard undefined symbols,
or symbols needed for relocations.
-You may only specify @samp{-retain-symbols-file} once in the command
+You may only specify @samp{--retain-symbols-file} once in the command
line. It overrides @samp{-s} and @samp{-S}.
@ifset GENERIC
On SunOS, if the @code{-rpath} option was not used, search any
directories specified using @code{-L} options.
@item
-For a native linker, the contents of the environment variable
-@code{LD_LIBRARY_PATH}.
-@item
-The default directories, normally @file{/lib} and @file{/usr/lib}.
-@end enumerate
-
-If the required shared library is not found, the linker will issue a
-warning and continue with the link.
-@end ifset
-
-@cindex partial link
-@cindex relocatable output
-@kindex -r
-@item -r
-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
-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}.
-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}.
-
-This option does the same thing as @samp{-i}.
-
-@kindex -S
-@cindex strip debugger symbols
-@item -S
-Omit debugger symbol information (but not all symbols) from the output file.
-
-@kindex -s
-@cindex strip all symbols
-@item -s
-Omit all symbol information from the output file.
-
-@ifset GENERIC
-@cindex runtime library name
-@kindex -soname
-@item -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
-which has a DT_SONAME field, then when the executable is run the dynamic
-linker will attempt to load the shared object specified by the DT_SONAME
-field rather than the using the file name given to the linker.
+For a native linker, the contents of the environment variable
+@code{LD_LIBRARY_PATH}.
+@item
+The default directories, normally @file{/lib} and @file{/usr/lib}.
+@end enumerate
+
+If the required shared library is not found, the linker will issue a
+warning and continue with the link.
@end ifset
+@kindex -shared
+@kindex -Bshareable
@item -shared
+@itemx -Bshareable
@cindex shared libraries
-@kindex -shared
-Create a shared library. This is currently only supported on ELF and
-SunOS platforms. On SunOS, the linker will automatically create a
+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
undefined symbols in the link.
-@item -sort-common
-@kindex -sort-common
-Normally, when @code{ld} places the global common symbols in the
-appropriate output sections, it sorts them by size. 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. This option disables that sorting.
-
-@kindex split
-@item -split-by-reloc @var{count}
-Trys 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 for downloading into
-certain real time kernels with the COFF object file format; since
-COFF cannot represent more than 65535 relocations in a single section.
-Note that this will fail to work with object file formats which do not
-support arbitrary sections. The linker will not split up individual input
-sections for redistribution, so if a single input section contains
+@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.
+
+@kindex --split-by-file
+@item --split-by-file
+Similar to @code{--split-by-reloc} but creates a new output section for
+each input file.
+
+@kindex --split-by-reloc
+@item --split-by-reloc @var{count}
+Trys 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 for downloading into
+certain real time kernels with the COFF object file format; since COFF
+cannot represent more than 65535 relocations in a single section. Note
+that this will fail to work with object file formats which do not
+support arbitrary sections. The linker will not split up individual
+input sections for redistribution, so if a single input section contains
more than @var{count} relocations one output section will contain that
many relocations.
-@kindex split
-@item -split-by-file
-Similar to -split-by-reloc but creates a new output section for each
-input file.
+@kindex --stats
+@item --stats
+Compute and display statistics about the operation of the linker, such
+as execution time and memory usage.
+
+@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
+use the traditional format instead.
-@item -stats
-Compute and display statistics about the operation of the linker,
-such as execution time and memory usage.
+@cindex dbx
+For example, on SunOS, @code{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
+combine duplicate entries.
@kindex -Tbss @var{org}
@kindex -Tdata @var{org}
for compatibility with other linkers, you may omit the leading
@samp{0x} usually associated with hexadecimal values.
-@kindex -T @var{script}
-@cindex script files
-@item -T @var{commandfile}
-@itemx -T@var{commandfile}
-Read link commands from the file @var{commandfile}. These commands
-replace @code{ld}'s default link script (rather than adding
-to it), so @var{commandfile} must specify everything necessary to describe
-the target format. @xref{Commands}. If @var{commandfile} does not
-exist, @code{ld} looks for it in the directories specified by any
-preceding @samp{-L} options. Multiple @samp{-T} options accumulate.
-
-@kindex -t
-@cindex verbose
-@cindex input files, displaying
-@item -t
-Print the names of the input files as @code{ld} processes them.
-
-@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
-use the traditional format instead.
-
-@cindex dbx
-For example, on SunOS, @code{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
-combine duplicate entries.
-
-@kindex -u @var{symbol}
-@cindex undefined symbol
-@item -u @var{symbol}
-Force @var{symbol} to be entered in the output file as an undefined symbol.
-Doing this may, for example, trigger linking of additional modules from
-standard libraries. @samp{-u} may be repeated with different option
-arguments to enter additional undefined symbols.
-@c Nice idea, but no such command: This option is equivalent
-@c to the @code{EXTERN} linker command.
-
@kindex -Ur
@cindex constructors
@item -Ur
@samp{-r} for the others.
@kindex --verbose
-@cindex version
+@cindex verbose
@item --verbose
Display the version number for @code{ld} and list the linker emulations
-supported. Display which input files can and cannot be opened.
-
-@kindex -v
-@kindex -V
-@cindex version
-@item -v
-@itemx -V
-Display the version number for @code{ld}. The @code{-V} option also
-lists the supported emulations.
-
-@kindex -version
-@item -version
-Display the version number for @code{ld} and exit.
-
-@kindex -warn-comon
+supported. Display which input files can and cannot be opened. Display
+the linker script if using a default builtin script.
+
+@kindex --version-script=@var{version-scriptfile}
+@cindex version script, symbol versions
+@itemx --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
+is only meaningful on ELF platforms which support shared libraries.
+@xref{Version Script}.
+
+@kindex --warn-comon
@cindex warnings, on combining symbols
@cindex combining symbols, warnings on
-@item -warn-common
+@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,
but linkers on some other operating systems do not. This option allows
a definition of the same variable.
@end table
-The @samp{-warn-common} option can produce five kinds of warnings. Each
-warning consists of a pair of lines: the first describes the symbol just
-encountered, and the second describes the previous symbol encountered
-with the same name. One or both of the two symbols will be a common
-symbol.
+The @samp{--warn-common} option can produce five kinds of warnings.
+Each warning consists of a pair of lines: the first describes the symbol
+just encountered, and the second describes the previous symbol
+encountered with the same name. One or both of the two symbols will be
+a common symbol.
@enumerate
@item
@end smallexample
@end enumerate
-@kindex -warn-constructors
-@item -warn-constructors
+@kindex --warn-constructors
+@item --warn-constructors
Warn if any global constructors are used. This is only useful for a few
object file formats. For formats like COFF or ELF, the linker can not
detect the use of global constructors.
-@kindex -warn-once
+@kindex --warn-multiple-gp
+@item --warn-multiple-gp
+Warn if multiple global pointer values are required in the output file.
+This is only meaningful for certain processors, such as the Alpha.
+Specifically, some processors put large-valued constants in a special
+section. A special register (the global pointer) points into the middle
+of this section, so that constants can be loaded efficiently via a
+base-register relative addressing mode. Since the offset in
+base-register relative mode is fixed and relatively small (e.g., 16
+bits), this limits the maximum size of the constant pool. Thus, in
+large programs, it is often necessary to use multiple global pointer
+values in order to be able to address all possible constants. This
+option causes a warning to be issued whenever this case occurs.
+
+@kindex --warn-once
@cindex warnings, on undefined symbols
@cindex undefined symbols, warnings on
-@item -warn-once
+@item --warn-once
Only warn once for each undefined symbol, rather than once per module
which refers to it.
+@kindex --warn-section-align
+@cindex warnings, on section alignment
+@cindex section alignment, warnings on
+@item --warn-section-align
+Warn if the address of an output section is changed because of
+alignment. Typically, the alignment will be set by an input section.
+The address will only be changed if it not explicitly specified; that
+is, if the @code{SECTIONS} command does not specify a start address for
+the section (@pxref{SECTIONS}).
+
@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
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.
+library. This option may be used more than once.
-@kindex --no-whole-archive
-Turn off the effect of the @code{--whole-archive} option for archives
-which appear later on the command line.
-
-@kindex -X
-@cindex local symbols, deleting
-@cindex L, deleting symbols beginning
-@item -X
-Delete all temporary local symbols. For most targets, this is all local
-symbols whose names begin with @samp{L}.
+@kindex --wrap
+@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
+@var{symbol}.
-@kindex -x
-@cindex deleting local symbols
-@item -x
-Delete all local symbols.
+This can be used to provide a wrapper for a system function. The
+wrapper function should be called @code{__wrap_@var{symbol}}. If it
+wishes to call the system function, it should call
+@code{__real_@var{symbol}}.
-@kindex -y @var{symbol}
-@cindex symbol tracing
-@item -y @var{symbol}
-Print the name of each linked file in which @var{symbol} appears. This
-option may be given any number of times. On many systems it is necessary
-to prepend an underscore.
+Here is a trivial example:
-This option is useful when you have an undefined symbol in your link but
-don't know where the reference is coming from.
+@smallexample
+void *
+__wrap_malloc (int c)
+@{
+ printf ("malloc called with %ld\n", c);
+ return __real_malloc (c);
+@}
+@end smallexample
-@kindex -(
-@cindex groups of archives
-@item -( @var{archives} -)
-@itemx --start-group @var{archives} --end-group
-The @var{archives} should be a list of archive files. They may be
-either explicit file names, or @samp{-l} options.
+If you link other code with this file using @code{--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.
-The specified archives are searched repeatedly until no new undefined
-references are created. Normally, an archive is searched only once in
-the order that it is specified on the command line. If a symbol in that
-archive is needed to resolve an undefined symbol referred to by an
-object in an archive that appears later on the command line, the linker
-would not be able to resolve that reference. By grouping the archives,
-they all be searched repeatedly until all possible references are
-resolved.
+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,
+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}.
-Using this option has a significant performance cost. It is best to use
-it only when there are unavoidable circular references between two or
-more archives.
@end table
@ifset UsesEnvVars
@node Environment
@section Environment Variables
-You can change the behavior of @code{ld} with the environment
-variable @code{GNUTARGET}.
+You can change the behavior of @code{ld} with the environment variables
+@code{GNUTARGET} and @code{LDEMULATION}.
@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
+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
-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 there is no method
-of ensuring that the magic number used to specify 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.
+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
+there is no method of ensuring that the magic number used to specify
+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.
+
+@kindex LDEMULATION
+@cindex default emulation
+@cindex emulation, default
+@code{LDEMULATION} determines the default emulation if you don't use the
+@samp{-m} option. The emulation can affect various aspects of linker
+behaviour, particularly the default linker script. You can list the
+available emulations with the @samp{--verbose} or @samp{-V} options. If
+the @samp{-m} option is not used, and the @code{LDEMULATION} environment
+variable is not defined, the default emulation depends upon how the
+linker was configured.
@end ifset
@node Commands
placement of common blocks
@end itemize
-You may supply a command file (also known as a link script) to the
+You may supply a command file (also known as a linker script) to the
linker either explicitly through the @samp{-T} option, or implicitly as
-an ordinary file. If the linker opens a file which it cannot recognize
-as a supported object or archive format, it reports an error.
+an ordinary file. Normally you should use the @samp{-T} option. An
+implicit linker script should only be used when you want to augment,
+rather than replace, the default linker script; typically an implicit
+linker script would consist only of @code{INPUT} or @code{GROUP}
+commands.
+
+If the linker opens a file which it cannot recognize as a supported
+object or archive format, nor as a linker script, it reports an error.
@menu
* Scripts:: Linker Scripts
* SECTIONS:: SECTIONS Command
* PHDRS:: PHDRS Command
* Entry Point:: The Entry Point
+* Version Script:: Version Script
* Option Commands:: Option Commands
@end menu
* Evaluation:: Evaluation
* Assignment:: Assignment: Defining Symbols
* Arithmetic Functions:: Built-In Functions
+* Semicolons:: Semicolon Usage
@end menu
@node Integers
@cindex negative integers
To write a negative integer, use
-the prefix operator @samp{-}; @pxref{Operators}.
+the prefix operator @samp{-} (@pxref{Operators}).
@smallexample
_as_neg = -57005;
@end smallexample
@end smallexample
Notes:
(1) Prefix operators
-(2) @xref{Assignment}
+(2) @xref{Assignment}.
@c TEXI2ROFF-KILL
@end ifinfo
@tex
\vskip \baselineskip
-%"lispnarrowing" is the extra indent used generally for @smallexample
+%"lispnarrowing" is the extra indent used generally for smallexample
\hskip\lispnarrowing\vbox{\offinterlineskip
\hrule
\halign
@end group
@end smallexample
+@kindex LOADADDR(@var{section})
+@cindex section load address
+@item LOADADDR(@var{section})
+Return the absolute load address of the named @var{section}. This is
+normally the same as @code{ADDR}, but it may be different if the
+@code{AT} keyword is used in the section definition (@pxref{Section
+Options}).
+
@kindex ALIGN(@var{exp})
@cindex rounding up location counter
@item ALIGN(@var{exp})
as the start address of the first section, if you choose, to facilitate
paging.
+@kindex MAX
+@item MAX(@var{exp1}, @var{exp2})
+Returns the maximum of @var{exp1} and @var{exp2}.
+
+@kindex MIN
+@item MIN(@var{exp1}, @var{exp2})
+Returns the minimum of @var{exp1} and @var{exp2}.
+
+@end table
+
+@node Semicolons
+@subsection Semicolons
+
+Semicolons (``@key{;}'') are required in the following places. In all
+other places they can appear for aesthetic reasons but are otherwise ignored.
+
+@table @code
+@item Assignment
+Semicolons must appear at the end of assignment expressions.
+@xref{Assignment}
+
+@item PHDRS
+Semicolons must appear at the end of a @code{PHDRS} statement.
+@xref{PHDRS}
@end table
@node MEMORY
@cindex memory region attributes
@item (@var{attr})
-is an optional list of attributes, permitted for compatibility with the
-AT&T linker but not used by @code{ld} beyond checking that the
-attribute list is valid. Valid attribute lists must be made up of the
-characters ``@code{LIRWX}''. If you omit the attribute list, you may
-omit the parentheses around it as well.
+is an optional list of attributes that specify whether to use a
+particular memory to place sections that are not listed in the linker
+script. Valid attribute lists must be made up of the characters
+``@code{ALIRWX}'' that match section attributes. If you omit the
+attribute list, you may omit the parentheses around it as well. The
+attributes currently supported are:
+
+@table @samp
+@item @code{Letter}
+@code{Section Attribute}
+
+@item @code{R}
+Read-only sections.
+
+@item @code{W}
+Read/write sections.
+
+@item @code{X}
+Sections containing executable code.
+
+@item @code{A}
+Allocated sections.
+
+@item @code{I}
+Initialized sections.
+
+@item @code{L}
+Same as @code{I}.
+
+@item @code{!}
+Invert the sense of any of the following attributes.
+@end table
@kindex ORIGIN =
@kindex o =
@end table
For example, to specify that memory has two regions available for
-allocation---one starting at 0 for 256 kilobytes, and the other
-starting at @code{0x40000000} for four megabytes:
+allocation---one starting at 0 for 256 kilobytes, and the other starting
+at @code{0x40000000} for four megabytes. The @code{rom} memory region
+will get all sections without an explicit memory register that are
+either read-only or contain code, while the @code{ram} memory region
+will get the sections.
@smallexample
@group
MEMORY
@{
- rom : ORIGIN = 0, LENGTH = 256K
- ram : org = 0x40000000, l = 4M
+ rom (rx) : ORIGIN = 0, LENGTH = 256K
+ ram (!rx) : org = 0x40000000, l = 4M
@}
@end group
@end smallexample
You can also use the first two operations---defining the entry point and
defining symbols---outside the @code{SECTIONS} command: @pxref{Entry
-Point}, and @pxref{Assignment}. They are permitted here as well for
+Point}, and @ref{Assignment}. They are permitted here as well for
your convenience in reading the script, so that symbols and the entry
point can be defined at meaningful points in your output-file layout.
* Section Placement:: Section Placement
* Section Data Expressions:: Section Data Expressions
* Section Options:: Optional Section Attributes
+* Overlays:: Overlays
@end menu
@node Section Definition
@noindent
@var{secname} is the name of the output section, and @var{contents} a
specification of what goes there---for example, a list of input files or
-sections of input files (@pxref{Section Placement}). As you might
-assume, the whitespace shown is optional. You do need the colon
-@samp{:} and the braces @samp{@{@}}, however.
+sections of input files (@pxref{Section Placement}). The whitespace
+around @var{secname} is required, so that the section name is
+unambiguous. The other whitespace shown is optional. You do need the
+colon @samp{:} and the braces @samp{@{@}}, however.
@var{secname} must meet the constraints of your output format. In
formats which only support a limited number of sections, such as
@code{ld} symbol name syntax must be quoted.
@xref{Symbols, , Symbol Names}.
+The special @var{secname} @samp{/DISCARD/} may be used to discard input
+sections. Any sections which are assigned to an output section named
+@samp{/DISCARD/} are not included in the final link output.
+
The linker will not create output sections which do not have any
contents. This is for convenience when referring to input sections that
may or may not exist. For example,
The @var{contents} of a section definition may include any of the
following kinds of statement. You can include as many of these as you
like in a single section definition, separated from one another by
-whitespace.
+whitespace.
@table @code
@kindex @var{filename}
@kindex @var{filename}(@var{section})
@cindex files and sections, section defn
@item @var{filename}( @var{section} )
-@itemx @var{filename}( @var{section}, @var{section}, @dots{} )
+@itemx @var{filename}( @var{section} , @var{section}, @dots{} )
@itemx @var{filename}( @var{section} @var{section} @dots{} )
-You can name one or more sections from your input files, for
-insertion in the current output section. If you wish to specify a list
-of input-file sections inside the parentheses, you may separate the
-section names by either commas or whitespace.
+You can name one or more sections from your input files, for insertion
+in the current output section. If you wish to specify a list of
+input-file sections inside the parentheses, separate the section names
+with whitespace.
@cindex input sections to output section
@kindex *(@var{section})
input file's format.
@end table
-For example, the following command script arranges the output file into
-three consecutive sections, named @code{.text}, @code{.data}, and
+In any place where you may use a specific file or section name, you may
+also use a wildcard pattern. The linker handles wildcards much as the
+Unix shell does. A @samp{*} character matches any number of characters.
+A @samp{?} character matches any single character. The sequence
+@samp{[@var{chars}]} will match a single instance of any of the
+@var{chars}; the @samp{-} character may be used to specify a range of
+characters, as in @samp{[a-z]} to match any lower case letter. A
+@samp{\} character may be used to quote the following character.
+
+When a file name is matched with a wildcard, the wildcard characters
+will not match a @samp{/} character (used to separate directory names on
+Unix). A pattern consisting of a single @samp{*} character is an
+exception; it will always match any file name. In a section name, the
+wildcard characters will match a @samp{/} character.
+
+Wildcards only match files which are explicitly specified on the command
+line. The linker does not search directories to expand wildcards.
+However, if you specify a simple file name---a name with no wildcard
+characters---in a linker script, and the file name is not also specified
+on the command line, the linker will attempt to open the file as though
+it appeared on the command line.
+
+In the following example, the command script arranges the output file
+into three consecutive sections, named @code{.text}, @code{.data}, and
@code{.bss}, taking the input for each from the correspondingly named
sections of all the input files:
@end group
@end smallexample
+This example shows how wildcard patterns might be used to partition
+files. All @code{.text} sections are placed in @code{.text}, and all
+@code{.bss} sections are placed in @code{.bss}. For all files beginning
+with an upper case character, the @code{.data} section is placed into
+@code{.DATA}; for all other files, the @code{.data} section is placed
+into @code{.data}.
+
+@smallexample
+@group
+SECTIONS @{
+ .text : @{ *(.text) @}
+ .DATA : @{ [A-Z]*(.data) @}
+ .data : @{ *(.data) @}
+ .bss : @{ *(.bss) @}
+@}
+@end group
+@end smallexample
+
@node Section Data Expressions
@subsection Section Data Expressions
The foregoing statements arrange, in your output file, data originating
from your input files. You can also place data directly in an output
section from the link command script. Most of these additional
-statements involve expressions; @pxref{Expressions}. Although these
+statements involve expressions (@pxref{Expressions}). Although these
statements are shown separately here for ease of presentation, no such
segregation is needed within a section definition in the @code{SECTIONS}
command; you can intermix them freely with any of the statements we've
@kindex SHORT(@var{expression})
@kindex LONG(@var{expression})
@kindex QUAD(@var{expression})
+@kindex SQUAD(@var{expression})
@cindex direct output
@item BYTE(@var{expression})
@itemx SHORT(@var{expression})
@itemx LONG(@var{expression})
@itemx QUAD(@var{expression})
+@itemx SQUAD(@var{expression})
By including one of these four statements in a section definition, you
-can explicitly place one, two, four, or eight bytes (respectively) at
-the current address of that section. @code{QUAD} is only supported when
-using a 64 bit host or target.
+can explicitly place one, two, four, eight unsigned, or eight signed
+bytes (respectively) at the current address of that section. When using
+a 64 bit host or target, @code{QUAD} and @code{SQUAD} are the same.
+When both host and target are 32 bits, @code{QUAD} uses an unsigned 32
+bit value, and @code{SQUAD} sign extends the value. Both will use the
+correct endianness when writing out the value.
@ifclear SingleFormat
Multiple-byte quantities are represented in whatever byte order is
@end smallexample
@var{secname} and @var{contents} are required. @xref{Section
-Definition}, and @pxref{Section Placement} for details on
+Definition}, and @ref{Section Placement}, for details on
@var{contents}. The remaining elements---@var{start},
@code{BLOCK(@var{align)}}, @code{(NOLOAD)}, @code{AT ( @var{ldadr} )},
@code{>@var{region}}, @code{:@var{phdr}}, and @code{=@var{fill}}---are
@cindex prevent unnecessary loading
@cindex loading, preventing
@item (NOLOAD)
-Use @samp{(NOLOAD)} to prevent a section from being loaded into memory
-each time it is accessed. For example, in the script sample below, the
-@code{ROM} segment is addressed at memory location @samp{0} and does not
-need to be loaded into each object file:
+The @samp{(NOLOAD)} directive will mark a section to not be loaded at
+run time. The linker will process the section normally, but will mark
+it so that a program loader will not load it into memory. For example,
+in the script sample below, the @code{ROM} section is addressed at
+memory location @samp{0} and does not need to be loaded when the program
+is run. The contents of the @code{ROM} section will appear in the
+linker output file as usual.
@smallexample
@group
@cindex program headers and sections
@item :@var{phdr}
Assign this section to a segment described by a program header.
-@xref{PHDRS}. If a section is assigned to one or more segments, than
+@xref{PHDRS}. If a section is assigned to one or more segments, then
all subsequent allocated sections will be assigned to those segments as
well, unless they use an explicitly @code{:@var{phdr}} modifier. To
prevent a section from being assigned to a segment when it would
@end table
+@node Overlays
+@subsection Overlays
+@kindex OVERLAY
+@cindex overlays
+
+The @code{OVERLAY} command provides an easy way to describe sections
+which are to be loaded as part of a single memory image but are to be
+run at the same memory address. At run time, some sort of overlay
+manager will copy the overlaid sections in and out of the runtime memory
+address as required, perhaps by simply manipulating addressing bits.
+This approach can be useful, for example, when a certain region of
+memory is faster than another.
+
+The @code{OVERLAY} command is used within a @code{SECTIONS} command. It
+appears as follows:
+@smallexample
+@group
+ OVERLAY @var{start} : [ NOCROSSREFS ] AT ( @var{ldaddr} )
+ @{
+ @var{secname1} @{ @var{contents} @} :@var{phdr} =@var{fill}
+ @var{secname2} @{ @var{contents} @} :@var{phdr} =@var{fill}
+ @dots{}
+ @} >@var{region} :@var{phdr} =@var{fill}
+@end group
+@end smallexample
+
+Everything is optional except @code{OVERLAY} (a keyword), and each
+section must have a name (@var{secname1} and @var{secname2} above). The
+section definitions within the @code{OVERLAY} construct are identical to
+those within the general @code{SECTIONS} contruct (@pxref{SECTIONS}),
+except that no addresses and no memory regions may be defined for
+sections within an @code{OVERLAY}.
+
+The sections are all defined with the same starting address. The load
+addresses of the sections are arranged such that they are consecutive in
+memory starting at the load address used for the @code{OVERLAY} as a
+whole (as with normal section definitions, the load address is optional,
+and defaults to the start address; the start address is also optional,
+and defaults to @code{.}).
+
+If the @code{NOCROSSREFS} keyword is used, and there any references
+among the sections, the linker will report an error. Since the sections
+all run at the same address, it normally does not make sense for one
+section to refer directly to another. @xref{Option Commands,
+NOCROSSREFS}.
+
+For each section within the @code{OVERLAY}, the linker automatically
+defines 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
+within C identifiers are removed. C (or assembler) code may use these
+symbols to move the overlaid sections around as necessary.
+
+At the end of the overlay, the value of @code{.} is set to the start
+address of the overlay plus the size of the largest section.
+
+Here is an example. Remember that this would appear inside a
+@code{SECTIONS} construct.
+
+@smallexample
+@group
+ OVERLAY 0x1000 : AT (0x4000)
+ @{
+ .text0 @{ o1/*.o(.text) @}
+ .text1 @{ o2/*.o(.text) @}
+ @}
+@end group
+@end smallexample
+
+This will define both @code{.text0} and @code{.text1} to start at
+address 0x1000. @code{.text0} will be loaded at address 0x4000, and
+@code{.text1} will be loaded immediately after @code{.text0}. The
+following symbols will be defined: @code{__load_start_text0},
+@code{__load_stop_text0}, @code{__load_start_text1},
+@code{__load_stop_text1}.
+
+C code to copy overlay @code{.text1} into the overlay area might look
+like the following.
+
+@smallexample
+@group
+ extern char __load_start_text1, __load_stop_text1;
+ memcpy ((char *) 0x1000, &__load_start_text1,
+ &__load_stop_text1 - &__load_start_text1);
+@end group
+@end smallexample
+
+Note that the @code{OVERLAY} command is just syntactic sugar, since
+everything it does can be done using the more basic commands. The above
+example could have been written identically as follows.
+
+@smallexample
+@group
+ .text0 0x1000 : AT (0x4000) @{ o1/*.o(.text) @}
+ __load_start_text0 = LOADADDR (.text0);
+ __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);
+ . = 0x1000 + MAX (SIZEOF (.text0), SIZEOF (.text1));
+@end group
+@end smallexample
+
@node PHDRS
@section ELF Program Headers
@kindex PHDRS
-@kindex program headers
-@kindex ELF program headers
+@cindex program headers
+@cindex ELF program headers
The ELF object file format uses @dfn{program headers}, which are read by
the system loader and describe how the program should be loaded into
start = other_symbol ;
@end smallexample
+@node Version Script
+@section Version Script
+@kindex VERSION @{script text@}
+@cindex symbol versions
+@cindex version script
+@cindex versions of symbols
+The linker command script includes a command specifically for
+specifying a version script, and is only meaningful for ELF platforms
+that support shared libraries. A version script can be
+build directly into the linker script that you are using, or you
+can supply the version script as just another input file to the linker
+at the time that you link. The command script syntax is:
+@smallexample
+VERSION @{ version script contents @}
+@end smallexample
+The version script can also be specified to the linker by means of the
+@samp{--version-script} linker command line option.
+Version scripts are only meaningful when creating shared libraries.
+
+The format of the version script itself is identical to that used by
+Sun's linker in Solaris 2.5. Versioning is done by defining a tree of
+version nodes with the names and interdependencies specified in the
+version script. The version script can specify which symbols are bound
+to which version nodes, and it can reduce a specified set of symbols to
+local scope so that they are not globally visible outside of the shared
+library.
+
+The easiest way to demonstrate the version script language is with a few
+examples.
+
+@smallexample
+VERS_1.1 @{
+ global:
+ foo1;
+ local:
+ old*;
+ original*;
+ new*;
+@};
+
+VERS_1.2 @{
+ foo2;
+@} VERS_1.1;
+
+VERS_2.0 @{
+ bar1; bar2;
+@} VERS_1.2;
+@end smallexample
+
+In this example, three version nodes are defined. @samp{VERS_1.1} is the
+first version node defined, and has no other dependencies. The symbol
+@samp{foo1} is bound to this version node, and a number of symbols
+that have appeared within various object files are reduced in scope to
+local so that they are not visible outside of the shared library.
+
+Next, the node @samp{VERS_1.2} is defined. It depends upon
+@samp{VERS_1.1}. The symbol @samp{foo2} is bound to this version node.
+
+Finally, the node @samp{VERS_2.0} is defined. It depends upon
+@samp{VERS_1.2}. The symbols @samp{bar1} and @samp{bar2} are bound to
+this version node.
+
+Symbols defined in the library which aren't specifically bound to a
+version node are effectively bound to an unspecified base version of the
+library. It is possible to bind all otherwise unspecified symbols to a
+given version node using @samp{global: *} somewhere in the version
+script.
+
+Lexically 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.
+
+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 shared library it is
+linked against. Thus at runtime, the dynamic loader can make a quick check to
+make sure that the libraries you have linked against do in fact supply all
+of the version nodes that the application will need to resolve all of the
+dynamic symbols. In this way it is possible for the dynamic linker to know
+with certainty that all external symbols that it needs will be resolvable
+without having to search for each symbol reference.
+
+The symbol versioning is in effect a much more sophisticated way of
+doing minor version checking that SunOS does. The fundamental problem
+that is being addressed here is that typically references to external
+functions are bound on an as-needed basis, and are not all bound when
+the application starts up. If a shared library is out of date, a
+required interface may be missing; when the application tries to use
+that interface, it may suddenly and unexpectedly fail. With symbol
+versioning, the user will get a warning when they start their program if
+the libraries being used with the application are too old.
+
+There are several GNU extensions to Sun's versioning approach. The
+first of these is the ability to bind a symbol to a version node in the
+source file where the symbol is defined instead of in the versioning
+script. This was done mainly to reduce the burden on the library
+maintainer. This can be done by putting something like:
+
+@smallexample
+__asm__(".symver original_foo,foo@@VERS_1.1");
+@end smallexample
+
+in the C source file. This renamed 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.
+
+The second GNU extension is to allow multiple versions of the same function
+to appear in a given shared library. In this way an incompatible change to
+an interface can take place without increasing the major version number of
+the shared library, while still allowing applications linked against the old
+interface to continue to function.
+
+This can only be accomplished by using multiple @samp{.symver}
+directives in the assembler. An example of this would be:
+
+@smallexample
+__asm__(".symver original_foo,foo@@");
+__asm__(".symver old_foo,foo@@VERS_1.1");
+__asm__(".symver old_foo1,foo@@VERS_1.2");
+__asm__(".symver new_foo,foo@@@@VERS_2.0");
+@end smallexample
+
+In this example, @samp{foo@@} represents the symbol @samp{foo} bound to the
+unspecified base version of the symbol. The source file that contains this
+example would define 4 C functions: @samp{original_foo}, @samp{old_foo},
+@samp{old_foo1}, and @samp{new_foo}.
+
+When you have multiple definitions of a given symbol, there needs to be
+some way to specify a default version to which external references to
+this symbol will be bound. This can be accomplished with the
+@samp{foo@@@@VERS_2.0} type of @samp{.symver} directive. Only one version of
+a symbol can be declared 'default' in this manner - otherwise you would
+effectively have multiple definitions of the same symbol.
+
+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
+specifically bind to an external version of the function in question.
+
@node Option Commands
@section Option Commands
The command language includes a number of other commands that you can
@cindex C++ constructors, arranging in link
@cindex constructors, arranging in link
@item CONSTRUCTORS
-This command ties up C++ style constructor and destructor records. The
-details of the constructor representation vary from one object format to
-another, but usually lists of constructors and destructors appear as
-special sections. The @code{CONSTRUCTORS} command specifies where the
-linker is to place the data from these sections, relative to the rest of
-the linked output. Constructor data is marked by the symbol
-@w{@code{__CTOR_LIST__}} at the start, and @w{@code{__CTOR_LIST_END}} at
-the end; destructor data is bracketed similarly, between
-@w{@code{__DTOR_LIST__}} and @w{@code{__DTOR_LIST_END}}. (The compiler
-must arrange to actually run this code; @sc{gnu} C++ calls constructors from
-a subroutine @code{__main}, which it inserts automatically into the
-startup code for @code{main}, and destructors from @code{_exit}.)
+When linking using the @code{a.out} object file format, the linker uses
+an unusual set construct to support C++ global constructors and
+destructors. When linking object file formats which do not support
+arbitrary sections, such as @code{ECOFF} and @code{XCOFF}, the linker
+will automatically recognize C++ global constructors and destructors by
+name. For these object file formats, the @code{CONSTRUCTORS} command
+tells the linker where this information should be placed. The
+@code{CONSTRUCTORS} command is 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
+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
+formats @sc{gnu} C++ calls constructors from a subroutine @code{__main};
+a call to @code{__main} is automatically inserted into the startup code
+for @code{main}. @sc{gnu} C++ runs destructors either by using
+@code{atexit}, or directly from the function @code{exit}.
+
+For object file formats such as @code{COFF} or @code{ELF} which support
+multiple sections, @sc{gnu} C++ will normally arrange to put the
+addresses of global constructors and destructors into the @code{.ctors}
+and @code{.dtors} sections. Placing the following sequence into your
+linker script will build the sort of table which the @sc{gnu} C++
+runtime code expects to see.
+
+@smallexample
+ __CTOR_LIST__ = .;
+ LONG((__CTOR_END__ - __CTOR_LIST__) / 4 - 2)
+ *(.ctors)
+ LONG(0)
+ __CTOR_END__ = .;
+ __DTOR_LIST__ = .;
+ LONG((__DTOR_END__ - __DTOR_LIST__) / 4 - 2)
+ *(.dtors)
+ LONG(0)
+ __DTOR_END__ = .;
+@end smallexample
+
+Normally the compiler and linker will handle these issues automatically,
+and you will not need to concern yourself with them. However, you may
+need to consider this if you are using C++ and writing your own linker
+scripts.
@need 1000
@kindex FLOAT
to make @code{ld} assign space to common symbols even if a relocatable
output file is specified (@samp{-r}).
+@kindex INCLUDE @var{filename}
+@cindex including a linker script
+@item INCLUDE @var{filename}
+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
+10 levels deep.
+
@kindex INPUT ( @var{files} )
@cindex binary input files
@item INPUT ( @var{file}, @var{file}, @dots{} )
you can use this command to specify a particular output format.
@var{bfdname} is one of the names used by the BFD back-end routines
(@pxref{BFD}). The effect is identical to the effect of the
-@samp{-oformat} command-line option. This selection affects only
-the output file; the related command @code{TARGET} affects primarily
-input files.
+@samp{--oformat} command-line option. This selection affects only the
+output file; the related command @code{TARGET} affects primarily input
+files.
@end ifclear
@kindex SEARCH_DIR ( @var{path} )
@item TARGET ( @var{format} )
When @code{ld} is configured to support multiple object code formats,
you can use this command to change the input-file object code format
-(like the command-line option @samp{-b} or its synonym @samp{-format}).
+(like the command-line option @samp{-b} or its synonym @samp{--format}).
The argument @var{format} is one of the strings used by BFD to name
binary formats. If @code{TARGET} is specified but @code{OUTPUT_FORMAT}
is not, the last @code{TARGET} argument is also used as the default
output file format. If that variable is also absent, @code{ld} uses
the default format configured for your machine in the BFD libraries.
@end ifclear
+
+@cindex cross references
+@kindex NOCROSSREFS ( @var{sections} )
+@item NOCROSSREFS ( @var{section} @var{section} @dots{} )
+This command may be used to tell @code{ld} to issue an error about any
+references among certain sections.
+
+In certain types of programs, particularly on embedded systems, 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 section names. If
+@code{ld} detects any cross references between the sections, it reports
+an error and returns a non-zero exit status. The @code{NOCROSSREFS}
+command uses output section names, defined in the @code{SECTIONS}
+command. It does not use the names of input sections.
@end table
@ifset GENERIC
@cindex H8/300 support
For the H8/300, @code{ld} can perform these global optimizations when
-you specify the @samp{-relax} command-line option.
+you specify the @samp{--relax} command-line option.
@table @emph
@cindex relaxing on H8/300
use will add another pair of name variants to search for when @w{@samp{-l}}
specifies a library.
-@cindex @code{-relax} on i960
+@cindex @code{--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 @code{calx}
-instructions whose targets are within 24 bits, and turns them into
-24-bit program-counter relative @code{bal} and @code{cal}
+@code{ld} supports the @samp{--relax} option for the i960 family. If
+you specify @samp{--relax}, @code{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 into @code{bal} instructions when it determines that the
target subroutine is a leaf routine (that is, the target subroutine does
@include bfdsumm.texi
@end ifclear
+@node Reporting Bugs
+@chapter Reporting Bugs
+@cindex bugs in @code{ld}
+@cindex reporting bugs in @code{ld}
+
+Your bug reports play an essential role in making @code{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}
+work better. Bug reports are your contribution to the maintenance of
+@code{ld}.
+
+In order for a bug report to serve its purpose, you must include the
+information that enables us to fix the bug.
+
+@menu
+* Bug Criteria:: Have you found a bug?
+* Bug Reporting:: How to report bugs
+@end menu
+
+@node Bug Criteria
+@section Have you found a bug?
+@cindex bug criteria
+
+If you are not sure whether you have found a bug, here are some guidelines:
+
+@itemize @bullet
+@cindex fatal signal
+@cindex linker crash
+@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.
+
+@cindex error on valid input
+@item
+If @code{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
+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.
+@end itemize
+
+@node Bug Reporting
+@section How to report bugs
+@cindex bug reports
+@cindex @code{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
+recommend you contact that organization first.
+
+You can find contact information for many support companies and
+individuals in the file @file{etc/SERVICE} in the @sc{gnu} Emacs
+distribution.
+
+In any event, we also recommend that you send bug reports for @code{ld}
+to @samp{bug-gnu-utils@@prep.ai.mit.edu}.
+
+The fundamental principle of reporting bugs usefully is this:
+@strong{report all the facts}. If you are not sure whether to state a
+fact or leave it out, state it!
+
+Often people omit facts because they think they know what causes the
+problem and assume that some details do not matter. Thus, you might
+assume that the name of a 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.
+
+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 @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}.
+
+@item
+Any patches you may have applied to the @code{ld} source, including any
+patches made to the @code{BFD} library.
+
+@item
+The type of machine you are using, and the operating system name and
+version number.
+
+@item
+What compiler (and its version) was used to compile @code{ld}---e.g.
+``@code{gcc-2.7}''.
+
+@item
+The command arguments you gave the linker to link your example and
+observe the bug. To guarantee you will not omit something important,
+list them all. A copy of the Makefile (or the output from make) is
+sufficient.
+
+If we were to try to guess the arguments, we would probably guess wrong
+and then we might not encounter the bug.
+
+@item
+A complete input file, or set of input files, that will reproduce the
+bug. It is generally most helpful to send the actual object files,
+uuencoded if necessary to get them through the mail system. Making them
+available for anonymous FTP is not as good, but may be the only
+reasonable choice for large object files.
+
+If the source files were assembled using @code{gas} or compiled using
+@code{gcc}, then it may be OK to send the source files rather than the
+object files. In this case, be sure to say exactly what version of
+@code{gas} or @code{gcc} was used to produce the object files. Also say
+how @code{gas} or @code{gcc} were configured.
+
+@item
+A description of what behavior you observe that you believe is
+incorrect. For example, ``It gets a fatal signal.''
+
+Of course, if the bug is that @code{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
+C library on your system. (This has happened!) Your copy might crash
+and ours would not. If you told us to expect a crash, then when ours
+fails to crash, we would know that the bug was not happening for us. If
+you had not told us to expect a crash, then we would not be able to draw
+any conclusion from our observations.
+
+@item
+If you wish to suggest changes to the @code{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
+context, not by line number.
+
+The line numbers in our development sources will not match those in your
+sources. Your line numbers would convey no useful information to us.
+@end itemize
+
+Here are some things that are not necessary:
+
+@itemize @bullet
+@item
+A description of the envelope of the bug.
+
+Often people who encounter a bug spend a lot of time investigating
+which changes to the input file will make the bug go away and which
+changes will not affect it.
+
+This is often time consuming and not very useful, because the way we
+will find the bug is by running a single example under the debugger
+with breakpoints, not by pure deduction from a series of examples.
+We recommend that you save your time for something else.
+
+Of course, if you can find a simpler example to report @emph{instead}
+of the original one, that is a convenience for us. Errors in the
+output will be easier to spot, running under the debugger will take
+less time, and so on.
+
+However, simplification is not vital; if you do not want to do this,
+report the bug anyway and send us the entire test case you used.
+
+@item
+A patch for the bug.
+
+A patch for the bug does help us if it is a good one. But do not omit
+the necessary information, such as the test case, on the assumption that
+a patch is all we need. We might see problems with your patch and decide
+to fix the problem another way, or we might not understand it at all.
+
+Sometimes with a program as complicated as @code{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
+fixed.
+
+And if we cannot understand what bug you are trying to fix, or why your
+patch should be an improvement, we will not install it. A test case will
+help us to understand.
+
+@item
+A guess about what the bug is or what it depends on.
+
+Such guesses are usually wrong. Even we cannot guess right about such
+things without first using the debugger to find the facts.
+@end itemize
+
@node MRI
@appendix MRI Compatible Script Files
@cindex MRI compatibility
@var{secname}, only the @emph{first} sets the start address.
@end table
-
@node Index
@unnumbered Index
projects / deliverable / binutils-gdb.git / blobdiff