1 .\" Copyright (c) 1991, 92, 93, 94, 95, 96, 1997 Free Software Foundation
2 .\" See section COPYING for conditions for redistribution
3 .TH ld 1 "17 August 1992" "cygnus support" "GNU Development Tools"
30 .RB "[\|" \-Bstatic "\|]"
31 .RB "[\|" \-Bdynamic "\|]"
32 .RB "[\|" \-Bsymbolic "\|]"
36 .RB "[\|" \-\-cref "\|]"
37 .RB "[\|" \-d | \-dc | \-dp\c
40 .RB "[\|" "\-defsym\ "\c
48 .RB "[\|" \-embedded\-relocs "\|]"
50 .RB "[\|" \-export\-dynamic "\|]"
54 .RB "[\|" "\-\-auxiliary\ "\c
60 .RB "[\|" "\-\-filter\ "\c
63 .RB "[\|" "\-format\ "\c
73 .RB "[\|" "\-soname\ "\c
76 .RB "[\|" \-\-help "\|]"
91 .RB "[\|" \-n | \-N "\|]"
92 .RB "[\|" \-noinhibit-exec "\|]"
93 .RB "[\|" \-no\-keep\-memory "\|]"
94 .RB "[\|" \-no\-warn\-mismatch "\|]"
98 .RB "[\|" "\-oformat\ "\c
104 .RB "[\|" \-relax "\|]"
105 .RB "[\|" \-r | \-Ur "\|]"
106 .RB "[\|" "\-rpath\ "\c
109 .RB "[\|" "\-rpath\-link\ "\c
114 .RB "[\|" \-shared "\|]"
115 .RB "[\|" \-sort\-common "\|]"
116 .RB "[\|" "\-split\-by\-reloc\ "\c
119 .RB "[\|" \-split\-by\-file "\|]"
123 .RB "[\|" "\-Ttext\ "\c
126 .RB "[\|" "\-Tdata\ "\c
129 .RB "[\|" "\-Tbss\ "\c
138 .RB "[\|" \-\-verbose "\|]"
139 .RB "[\|" \-\-version "\|]"
140 .RB "[\|" \-warn\-common "\|]"
141 .RB "[\|" \-warn\-constructors "\|]"
142 .RB "[\|" \-warn\-multiple\-gp "\|]"
143 .RB "[\|" \-warn\-once "\|]"
144 .RB "[\|" \-warn\-section\-align "\|]"
145 .RB "[\|" \-\-whole\-archive "\|]"
146 .RB "[\|" \-\-no\-whole\-archive "\|]"
147 .RB "[\|" "\-\-wrap\ "\c
157 \& combines a number of object and archive files, relocates
158 their data and ties up symbol references. Often the last step in
159 building a new compiled program to run is a call to \c
165 \& accepts Linker Command Language files
166 to provide explicit and total control over the linking process.
167 This man page does not describe the command language; see the `\|\c
174 \&, for full details on the command language and on other aspects of
179 \& uses the general purpose BFD libraries
180 to operate on object files. This allows \c
182 \& to read, combine, and
183 write object files in many different formats\(em\&for example, COFF or
186 \&. Different formats may be linked together to produce any
187 available kind of object file. You can use `\|\c
189 \|' to get a list of formats supported on various architectures; see
192 Aside from its flexibility, the GNU linker is more helpful than other
193 linkers in providing diagnostic information. Many linkers abandon
194 execution immediately upon encountering an error; whenever possible,
197 \& continues executing, allowing you to identify other errors
198 (or, in some cases, to get an output file in spite of the error).
202 \& is meant to cover a broad range of situations,
203 and to be as compatible as possible with other linkers. As a result,
204 you have many choices to control its behavior through the command line,
205 and through environment variables.
208 The plethora of command-line options may seem intimidating, but in
209 actual practice few of them are used in any particular context.
210 For instance, a frequent use of \c
212 \& is to link standard Unix
213 object files on a standard, supported Unix system. On such a system, to
219 $\ ld\ \-o\ output\ /lib/crt0.o\ hello.o\ \-lc
224 \& to produce a file called \c
227 result of linking the file \c
234 \& which will come from the standard search
237 The command-line options to \c
239 \& may be specified in any order, and
240 may be repeated at will. For the most part, repeating an option with a
241 different argument will either have no further effect, or override prior
242 occurrences (those further to the left on the command line) of an
245 The exceptions\(em\&which may meaningfully be used more than once\(em\&are
250 \& (or its synonym \c
265 The list of object files to be linked together, shown as \c
268 may follow, precede, or be mixed in with command-line options; save that
271 \& argument may not be placed between an option flag and
274 Usually the linker is invoked with at least one object file, but other
275 forms of binary input files can also be specified with \c
280 \&, and the script command language. If \c
283 files at all are specified, the linker does not produce any output, and
284 issues the message `\|\c
288 Option arguments must either follow the option letter without intervening
289 whitespace, or be given as separate arguments immediately following the
290 option that requires them.
293 .BI "-A" "architecture"
294 In the current release of \c
296 \&, this option is useful only for the
297 Intel 960 family of architectures. In that \c
299 \& configuration, the
302 \& argument is one of the two-letter names identifying
303 members of the 960 family; the option specifies the desired output
304 target, and warns of any incompatible instructions in the input files.
305 It also modifies the linker's search strategy for archive libraries, to
306 support the use of libraries specific to each particular
307 architecture, by including in the search loop names suffixed with the
308 string identifying the architecture.
310 For example, if your \c
312 \& command line included `\|\c
317 \|', the linker would look (in its built-in search
318 paths, and in any paths you specify with \c
320 \&) for a library with
334 The first two possibilities would be considered in any event; the last
335 two are due to the use of `\|\c
339 Future releases of \c
341 \& may support similar functionality for
342 other architecture families.
344 You can meaningfully use \c
346 \& more than once on a command line, if
347 an architecture family allows combination of target architectures; each
348 use will add another pair of name variants to search for when \c
353 .BI "\-b " "input-format"
354 Specify the binary format for input object files that follow this option
355 on the command line. You don't usually need to specify this, as
358 \& is configured to expect as a default input format the most
359 usual format on each machine. \c
361 \& is a text string, the
362 name of a particular format supported by the BFD libraries.
367 \& has the same effect, as does the script command
370 You may want to use this option if you are linking files with an unusual
371 binary format. You can also use \c
373 \& to switch formats explicitly (when
374 linking object files of different formats), by including
379 \& before each group of object files in a
382 The default format is taken from the environment variable
384 \&. You can also define the input
385 format from a script, using the command \c
391 Do not link against shared libraries. This is only meaningful on
392 platforms for which shared libraries are supported.
396 Link against dynamic libraries. This is only meaningful on platforms
397 for which shared libraries are supported. This option is normally the
398 default on such platforms.
402 When creating a shared library, bind references to global symbols to
403 the definition within the shared library, if any. Normally, it is
404 possible for a program linked against a shared library to override the
405 definition within the shared library. This option is only meaningful
406 on ELF platforms which support shared libraries.
409 .BI "\-c " "commandfile"
412 \& to read link commands from the file
415 \&. These commands will completely override \c
418 default link format (rather than adding to it); \c
421 specify everything necessary to describe the target format.
424 You may also include a script of link commands directly in the command
425 line by bracketing it between `\|\c
433 Output a cross reference table. If a linker map file is being
434 generated, the cross reference table is printed to the map file.
435 Otherwise, it is printed on the standard output.
443 These three options are equivalent; multiple forms are supported for
444 compatibility with other linkers. Use any of them to make \c
446 assign space to common symbols even if a relocatable output file is
449 \&). The script command
451 .B FORCE_COMMON_ALLOCATION\c
452 \& has the same effect.
455 .BI "-defsym " "symbol" "\fR = \fP" expression
456 Create a global symbol in the output file, containing the absolute
459 \&. You may use this option as many
460 times as necessary to define multiple symbols in the command line. A
461 limited form of arithmetic is supported for the \c
464 context: you may give a hexadecimal constant or the name of an existing
469 \& to add or subtract hexadecimal
470 constants or symbols. If you need more elaborate expressions, consider
471 using the linker command language from a script.
478 \& as the explicit symbol for beginning execution of your
479 program, rather than the default entry point. for a
480 discussion of defaults and other ways of specifying the
484 .B \-embedded\-relocs
485 This option is only meaningful when linking MIPS embedded PIC code,
488 option to the GNU compiler and assembler. It causes the linker to
489 create a table which may be used at runtime to relocate any data which
490 was statically initialized to pointer values. See the code in
491 testsuite/ld-empic for details.
497 When creating an ELF file, add all symbols to the dynamic symbol table.
498 Normally, the dynamic symbol table contains only symbols which are used
499 by a dynamic object. This option is needed for some uses of
505 .BI "--auxiliary " "name"
506 When creating an ELF shared object, set the internal DT_AUXILIARY field
507 to the specified name. This tells the dynamic linker that the symbol
508 table of the shared object should be used as an auxiliary filter on the
509 symbol table of the shared object
515 .BI "--filter " "name"
516 When creating an ELF shared object, set the internal DT_FILTER field to
517 the specified name. This tells the dynamic linker that the symbol table
518 of the shared object should be used as a filter on the symbol table of
523 .BI "\-format " "input\-format"
532 Accepted, but ignored; provided for compatibility with other tools.
536 Set the maximum size of objects to be optimized using the GP register
539 under MIPS ECOFF. Ignored for other object file formats.
544 .BI "-soname " "name"
545 When creating an ELF shared object, set the internal DT_SONAME field to
546 the specified name. When an executable is linked with a shared object
547 which has a DT_SONAME field, then when the executable is run the dynamic
548 linker will attempt to load the shared object specified by the DT_SONAME
549 field rather than the using the file name given to the linker.
553 Print a summary of the command-line options on the standard output and exit.
556 begin with two dashes instead of one
557 for compatibility with other GNU programs. The other options start with
558 only one dash for compatibility with other linkers.
562 Perform an incremental link (same as option \c
569 Add an archive file \c
571 \& to the list of files to link. This
572 option may be used any number of times. \c
575 path-list for occurrences of \c
584 .BI "\-L" "searchdir"
585 This command adds path \c
587 \& to the list of paths that
590 \& will search for archive libraries. You may use this option
593 The default set of paths searched (without being specified with
596 \&) depends on what emulation mode \c
599 some cases also on how it was configured. The
600 paths can also be specified in a link script with the \c
606 Print (to the standard output file) a link map\(em\&diagnostic information
607 about where symbols are mapped by \c
609 \&, and information on global
610 common storage allocation.
613 .BI "\-Map " "mapfile"\c
616 a link map\(em\&diagnostic information
617 about where symbols are mapped by \c
619 \&, and information on global
620 common storage allocation.
623 .BI "\-m " "emulation"\c
626 linker. You can list the available emulations with the
630 options. This option overrides the compiled-in default, which is the
631 system for which you configured
636 specifies readable and writable \c
641 the output format supports Unix style magic numbers, the output is
646 When you use the `\|\c
648 \&\|' option, the linker does not page-align the
653 sets the text segment to be read only, and \c
660 Normally, the linker will not produce an output file if it encounters
661 errors during the link process. With this flag, you can specify that
662 you wish the output file retained even after non-fatal errors.
665 .B \-no\-keep\-memory
666 The linker normally optimizes for speed over memory usage by caching
667 the symbol tables of input files in memory. This option tells the
668 linker to instead optimize for memory usage, by rereading the symbol
669 tables as necessary. This may be required if the linker runs out of
670 memory space while linking a large executable.
673 .B \-no\-warn\-mismatch
674 Normally the linker will give an error if you try to link together
675 input files that are mismatched for some reason, perhaps because they
676 have been compiled for different processors or for different
677 endiannesses. This option tells the linker that it should silently
678 permit such possible errors. This option should only be used with
679 care, in cases when you have taken some special action that ensures
680 that the linker errors are inappropriate.
685 \& is a name for the program produced by \c
688 option is not specified, the name `\|\c
690 \|' is used by default. The
693 \& can also specify the output file name.
697 Generate optimized output files. This might use significantly more
698 time and therefore probably should be enabled only for generating the
702 \& is supposed to be a numeric value. Any value greater than zero enables
706 .BI "\-oformat " "output\-format"
707 Specify the binary format for the output object file.
708 You don't usually need to specify this, as
711 \& is configured to produce as a default output format the most
712 usual format on each machine. \c
714 \& is a text string, the
715 name of a particular format supported by the BFD libraries.
718 can also specify the output format, but this option overrides it.
721 .BI "\-R " "filename"
722 Read symbol names and their addresses from \c
725 relocate it or include it in the output. This allows your output file
726 to refer symbolically to absolute locations of memory defined in other
731 An option with machine dependent effects. Currently this option is only
732 supported on the H8/300.
734 On some platforms, use this option to perform global optimizations that
735 become possible when the linker resolves addressing in your program, such
736 as relaxing address modes and synthesizing new instructions in the
739 On platforms where this is not supported, `\|\c
741 \&\|' is accepted, but has no effect.
745 Generates relocatable output\(em\&i.e., generate an output file that can in
746 turn serve as input to \c
748 \&. This is often called \c
751 \&. As a side effect, in environments that support standard Unix
752 magic numbers, this option also sets the output file's magic number to
756 If this option is not specified, an absolute file is produced. When
757 linking C++ programs, this option \c
759 \& resolve references to
762 \& is an alternative.
764 This option does the same as \c
769 .B \-rpath\ \fIdirectory
770 Add a directory to the runtime library search path. This is used when
771 linking an ELF executable with shared objects. All
773 arguments are concatenated and passed to the runtime linker, which uses
774 them to locate shared objects at runtime. The
776 option is also used when locating shared objects which are needed by
777 shared objects explicitly included in the link; see the description of
782 is not used when linking an ELF executable, the contents of the
785 will be used if it is defined.
789 option may also be used on SunOS. By default, on SunOS, the linker
790 will form a runtime search patch out of all the
792 options it is given. If a
794 option is used, the runtime search path will be formed exclusively
800 options. This can be useful when using gcc, which adds many
802 options which may be on NFS mounted filesystems.
805 .B \-rpath\-link\ \fIdirectory
806 When using ELF or SunOS, one shared library may require another. This
809 link includes a shared library as one of the input files.
811 When the linker encounters such a dependency when doing a non-shared,
812 non-relocateable link, it will automatically try to locate the required
813 shared library and include it in the link, if it is not included
814 explicitly. In such a case, the
816 option specifies the first set of directories to search. The
818 option may specify a sequence of directory names either by specifying
819 a list of names separated by colons, or by appearing multiple times.
821 If the required shared library is not found, the linker will issue a
822 warning and continue with the link.
826 Omits debugger symbol information (but not all symbols) from the output file.
830 Omits all symbol information from the output file.
834 Create a shared library. This is currently only supported on ELF and
835 SunOS platforms (on SunOS it is not required, as the linker will
836 automatically create a shared library when there are undefined symbols
845 places the global common symbols in the appropriate output sections,
846 it sorts them by size. First come all the one byte symbols, then all
847 the two bytes, then all the four bytes, and then everything else.
848 This is to prevent gaps between symbols due to
849 alignment constraints. This option disables that sorting.
852 .B \-split\-by\-reloc\ \fIcount
853 Trys to creates extra sections in the output file so that no single
854 output section in the file contains more than
857 This is useful when generating huge relocatable for downloading into
858 certain real time kernels with the COFF object file format; since COFF
859 cannot represent more than 65535 relocations in a single section.
860 Note that this will fail to work with object file formats which do not
861 support arbitrary sections. The linker will not split up individual
862 input sections for redistribution, so if a single input section
865 relocations one output section will contain that many relocations.
870 .B \-split\-by\-reloc
871 but creates a new output section for each input file.
874 .BI "\-Tbss " "org"\c
876 .BI "\-Tdata " "org"\c
878 .BI "\-Ttext " "org"\c
881 \& as the starting address for\(em\&respectively\(em\&the
888 \& segment of the output file.
891 \& must be a hexadecimal integer.
894 .BI "\-T " "commandfile"
899 \&; supported for compatibility with
904 Prints names of input files as \c
912 \& to be entered in the output file as an undefined symbol.
913 This may, for example, trigger linking of additional modules from
914 standard libraries. \c
916 \& may be repeated with different option
917 arguments to enter additional undefined symbols.
921 For anything other than C++ programs, this option is equivalent to
924 \&: it generates relocatable output\(em\&i.e., an output file that can in
925 turn serve as input to \c
927 \&. When linking C++ programs, \c
930 \& resolve references to constructors, unlike \c
936 Display the version number for \c
938 and list the supported emulations.
939 Display which input files can and can not be opened.
943 Display the version number for \c
948 option also lists the supported emulations.
952 Display the version number for \c
958 Warn when a common symbol is combined with another common symbol or with
959 a symbol definition. Unix linkers allow this somewhat sloppy practice,
960 but linkers on some other operating systems do not. This option allows
961 you to find potential problems from combining global symbols.
964 .B \-warn\-constructors
965 Warn if any global constructors are used. This is only useful for a
966 few object file formats. For formats like COFF or ELF, the linker can
967 not detect the use of global constructors.
970 .B \-warn\-multiple\-gp
971 Warn if the output file requires multiple global-pointer values. This
972 option is only meaningful for certain processors, such as the Alpha.
976 Only warn once for each undefined symbol, rather than once per module
980 .B \-warn\-section\-align
981 Warn if the address of an output section is changed because of
982 alignment. Typically, the alignment will be set by an input section.
983 The address will only be changed if it not explicitly specified; that
984 is, if the SECTIONS command does not specify a start address for the
988 .B \-\-whole\-archive
989 For each archive mentioned on the command line after the
990 .B \-\-whole\-archive
991 option, include every object file in the archive in the link, rather
992 than searching the archive for the required object files. This is
993 normally used to turn an archive file into a shared library, forcing
994 every object to be included in the resulting shared library.
997 .B \-\-no\-whole\-archive
998 Turn off the effect of the
999 .B \-\-whole\-archive
1000 option for archives which appear later on the command line.
1003 .BI "--wrap " "symbol"
1004 Use a wrapper function for
1006 Any undefined reference to
1009 .BI "__wrap_" "symbol".
1010 Any undefined reference to
1011 .BI "__real_" "symbol"
1017 Delete all temporary local symbols. For most targets, this is all local
1018 symbols whose names begin with `\|\c
1024 Delete all local symbols.
1030 You can change the behavior of
1032 \& with the environment variable \c
1038 \& determines the input-file object format if you don't
1041 \& (or its synonym \c
1043 \&). Its value should be one
1044 of the BFD names for an input format. If there is no
1047 \& in the environment, \c
1049 \& uses the natural format
1054 \& then BFD attempts to discover the
1055 input format by examining binary input files; this method often
1056 succeeds, but there are potential ambiguities, since there is no method
1057 of ensuring that the magic number used to flag object-file formats is
1058 unique. However, the configuration procedure for BFD on each system
1059 places the conventional format for that system first in the search-list,
1060 so ambiguities are resolved in favor of convention.
1069 .RB "`\|" ld "\|' and `\|" binutils "\|'"
1074 ld: the GNU linker\c
1075 , Steve Chamberlain and Roland Pesch;
1077 The GNU Binary Utilities\c
1081 Copyright (c) 1991, 1992 Free Software Foundation, Inc.
1083 Permission is granted to make and distribute verbatim copies of
1084 this manual provided the copyright notice and this permission notice
1085 are preserved on all copies.
1087 Permission is granted to copy and distribute modified versions of this
1088 manual under the conditions for verbatim copying, provided that the
1089 entire resulting derived work is distributed under the terms of a
1090 permission notice identical to this one.
1092 Permission is granted to copy and distribute translations of this
1093 manual into another language, under the above conditions for modified
1094 versions, except that this permission notice may be included in
1095 translations approved by the Free Software Foundation instead of in
1096 the original English.