1LD(1) GNU Development Tools LD(1)
2
6 ld - The GNU linker
7
9 ld [options] objfile ...
10
12 ld combines a number of object and archive files, relocates their data
13 and ties up symbol references. Usually the last step in compiling a
14 program is to run ld.
15 ld accepts Linker Command Language files written in a superset of
17 AT&T's Link Editor Command Language syntax, to provide explicit and
18 total control over the linking process.
19 This man page does not describe the command language; see the ld entry
21 in "info" for full details on the command language and on other aspects
22 of the GNU linker.
23 This version of ld uses the general purpose BFD libraries to operate on
25 object files. This allows ld to read, combine, and write object files
26 in many different formats---for example, COFF or "a.out". Different
27 formats may be linked together to produce any available kind of object
28 file.
29 Aside from its flexibility, the GNU linker is more helpful than other
31 linkers in providing diagnostic information. Many linkers abandon
32 execution immediately upon encountering an error; whenever possible, ld
33 continues executing, allowing you to identify other errors (or, in some
34 cases, to get an output file in spite of the error).
35 The GNU linker ld is meant to cover a broad range of situations, and to
37 be as compatible as possible with other linkers. As a result, you have
38 many choices to control its behavior.
39
41 The linker supports a plethora of command-line options, but in actual
42 practice few of them are used in any particular context. For instance,
43 a frequent use of ld is to link standard Unix object files on a
44 standard, supported Unix system. On such a system, to link a file
45 "hello.o":
46 ld -o <output> /lib/crt0.o hello.o -lc
48 This tells ld to produce a file called output as the result of linking
50 the file "/lib/crt0.o" with "hello.o" and the library "libc.a", which
51 will come from the standard search directories. (See the discussion of
52 the -l option below.)
53 Some of the command-line options to ld may be specified at any point in
55 the command line. However, options which refer to files, such as -l or
56 -T, cause the file to be read at the point at which the option appears
57 in the command line, relative to the object files and other file
58 options. Repeating non-file options with a different argument will
59 either have no further effect, or override prior occurrences (those
60 further to the left on the command line) of that option. Options which
61 may be meaningfully specified more than once are noted in the
62 descriptions below.
63 Non-option arguments are object files or archives which are to be
65 linked together. They may follow, precede, or be mixed in with
66 command-line options, except that an object file argument may not be
67 placed between an option and its argument.
68 Usually the linker is invoked with at least one object file, but you
70 can specify other forms of binary input files using -l, -R, and the
71 script command language. If no binary input files at all are
72 specified, the linker does not produce any output, and issues the
73 message No input files.
74 If the linker cannot recognize the format of an object file, it will
76 assume that it is a linker script. A script specified in this way
77 augments the main linker script used for the link (either the default
78 linker script or the one specified by using -T). This feature permits
79 the linker to link against a file which appears to be an object or an
80 archive, but actually merely defines some symbol values, or uses
81 "INPUT" or "GROUP" to load other objects. Specifying a script in this
82 way merely augments the main linker script, with the extra commands
83 placed after the main script; use the -T option to replace the default
84 linker script entirely, but note the effect of the "INSERT" command.
85 For options whose names are a single letter, option arguments must
87 either follow the option letter without intervening whitespace, or be
88 given as separate arguments immediately following the option that
89 requires them.
90 For options whose names are multiple letters, either one dash or two
92 can precede the option name; for example, -trace-symbol and
93 --trace-symbol are equivalent. Note---there is one exception to this
94 rule. Multiple letter options that start with a lower case 'o' can
95 only be preceded by two dashes. This is to reduce confusion with the
96 -o option. So for example -omagic sets the output file name to magic
97 whereas --omagic sets the NMAGIC flag on the output.
98 Arguments to multiple-letter options must either be separated from the
100 option name by an equals sign, or be given as separate arguments
101 immediately following the option that requires them. For example,
102 --trace-symbol foo and --trace-symbol=foo are equivalent. Unique
103 abbreviations of the names of multiple-letter options are accepted.
104 Note---if the linker is being invoked indirectly, via a compiler driver
106 (e.g. gcc) then all the linker command-line options should be prefixed
107 by -Wl, (or whatever is appropriate for the particular compiler driver)
108 like this:
109 gcc -Wl,--start-group foo.o bar.o -Wl,--end-group
111 This is important, because otherwise the compiler driver program may
113 silently drop the linker options, resulting in a bad link. Confusion
114 may also arise when passing options that require values through a
115 driver, as the use of a space between option and argument acts as a
116 separator, and causes the driver to pass only the option to the linker
117 and the argument to the compiler. In this case, it is simplest to use
118 the joined forms of both single- and multiple-letter options, such as:
119 gcc foo.o bar.o -Wl,-eENTRY -Wl,-Map=a.map
121 Here is a table of the generic command-line switches accepted by the
123 GNU linker:
124 @file
126 Read command-line options from file. The options read are inserted
127 in place of the original @file option. If file does not exist, or
128 cannot be read, then the option will be treated literally, and not
129 removed.
130 Options in file are separated by whitespace. A whitespace
132 character may be included in an option by surrounding the entire
133 option in either single or double quotes. Any character (including
134 a backslash) may be included by prefixing the character to be
135 included with a backslash. The file may itself contain additional
136 @file options; any such options will be processed recursively.
137 -a keyword
139 This option is supported for HP/UX compatibility. The keyword
140 argument must be one of the strings archive, shared, or default.
141 -aarchive is functionally equivalent to -Bstatic, and the other two
142 keywords are functionally equivalent to -Bdynamic. This option may
143 be used any number of times.
144 --audit AUDITLIB
146 Adds AUDITLIB to the "DT_AUDIT" entry of the dynamic section.
147 AUDITLIB is not checked for existence, nor will it use the
148 DT_SONAME specified in the library. If specified multiple times
149 "DT_AUDIT" will contain a colon separated list of audit interfaces
150 to use. If the linker finds an object with an audit entry while
151 searching for shared libraries, it will add a corresponding
152 "DT_DEPAUDIT" entry in the output file. This option is only
153 meaningful on ELF platforms supporting the rtld-audit interface.
154 -b input-format
156 --format=input-format
157 ld may be configured to support more than one kind of object file.
158 If your ld is configured this way, you can use the -b option to
159 specify the binary format for input object files that follow this
160 option on the command line. Even when ld is configured to support
161 alternative object formats, you don't usually need to specify this,
162 as ld should be configured to expect as a default input format the
163 most usual format on each machine. input-format is a text string,
164 the name of a particular format supported by the BFD libraries.
165 (You can list the available binary formats with objdump -i.)
166 You may want to use this option if you are linking files with an
168 unusual binary format. You can also use -b to switch formats
169 explicitly (when linking object files of different formats), by
170 including -b input-format before each group of object files in a
171 particular format.
172 The default format is taken from the environment variable
174 "GNUTARGET".
175 You can also define the input format from a script, using the
177 command "TARGET";
178 -c MRI-commandfile
180 --mri-script=MRI-commandfile
181 For compatibility with linkers produced by MRI, ld accepts script
182 files written in an alternate, restricted command language,
183 described in the MRI Compatible Script Files section of GNU ld
184 documentation. Introduce MRI script files with the option -c; use
185 the -T option to run linker scripts written in the general-purpose
186 ld scripting language. If MRI-cmdfile does not exist, ld looks for
187 it in the directories specified by any -L options.
188 -d
190 -dc
191 -dp These three options are equivalent; multiple forms are supported
192 for compatibility with other linkers. They assign space to common
193 symbols even if a relocatable output file is specified (with -r).
194 The script command "FORCE_COMMON_ALLOCATION" has the same effect.
195 --depaudit AUDITLIB
197 -P AUDITLIB
198 Adds AUDITLIB to the "DT_DEPAUDIT" entry of the dynamic section.
199 AUDITLIB is not checked for existence, nor will it use the
200 DT_SONAME specified in the library. If specified multiple times
201 "DT_DEPAUDIT" will contain a colon separated list of audit
202 interfaces to use. This option is only meaningful on ELF platforms
203 supporting the rtld-audit interface. The -P option is provided for
204 Solaris compatibility.
205 --enable-non-contiguous-regions
207 This option avoids generating an error if an input section does not
208 fit a matching output section. The linker tries to allocate the
209 input section to subseque nt matching output sections, and
210 generates an error only if no output section is large enough. This
211 is useful when several non-contiguous memory regions are available
212 and the input section does not require a particular one. The order
213 in which input sections are evaluated does not change, for
214 instance:
215 MEMORY {
217 MEM1 (rwx) : ORIGIN : 0x1000, LENGTH = 0x14
218 MEM2 (rwx) : ORIGIN : 0x1000, LENGTH = 0x40
219 MEM3 (rwx) : ORIGIN : 0x2000, LENGTH = 0x40
220 }
221 SECTIONS {
222 mem1 : { *(.data.*); } > MEM1
223 mem2 : { *(.data.*); } > MEM2
224 mem3 : { *(.data.*); } > MEM2
225 }
226 with input sections:
228 .data.1: size 8
229 .data.2: size 0x10
230 .data.3: size 4
231 results in .data.1 affected to mem1, and .data.2 and .data.3
233 affected to mem2, even though .data.3 would fit in mem3.
234 This option is incompatible with INSERT statements because it
236 changes the way input sections are mapped to output sections.
237 --enable-non-contiguous-regions-warnings
239 This option enables warnings when "--enable-non-contiguous-regions"
240 allows possibly unexpected matches in sections mapping, potentially
241 leading to silently discarding a section instead of failing because
242 it does not fit any output region.
243 -e entry
245 --entry=entry
246 Use entry as the explicit symbol for beginning execution of your
247 program, rather than the default entry point. If there is no
248 symbol named entry, the linker will try to parse entry as a number,
249 and use that as the entry address (the number will be interpreted
250 in base 10; you may use a leading 0x for base 16, or a leading 0
251 for base 8).
252 --exclude-libs lib,lib,...
254 Specifies a list of archive libraries from which symbols should not
255 be automatically exported. The library names may be delimited by
256 commas or colons. Specifying "--exclude-libs ALL" excludes symbols
257 in all archive libraries from automatic export. This option is
258 available only for the i386 PE targeted port of the linker and for
259 ELF targeted ports. For i386 PE, symbols explicitly listed in a
260 .def file are still exported, regardless of this option. For ELF
261 targeted ports, symbols affected by this option will be treated as
262 hidden.
263 --exclude-modules-for-implib module,module,...
265 Specifies a list of object files or archive members, from which
266 symbols should not be automatically exported, but which should be
267 copied wholesale into the import library being generated during the
268 link. The module names may be delimited by commas or colons, and
269 must match exactly the filenames used by ld to open the files; for
270 archive members, this is simply the member name, but for object
271 files the name listed must include and match precisely any path
272 used to specify the input file on the linker's command-line. This
273 option is available only for the i386 PE targeted port of the
274 linker. Symbols explicitly listed in a .def file are still
275 exported, regardless of this option.
276 -E
278 --export-dynamic
279 --no-export-dynamic
280 When creating a dynamically linked executable, using the -E option
281 or the --export-dynamic option causes the linker to add all symbols
282 to the dynamic symbol table. The dynamic symbol table is the set
283 of symbols which are visible from dynamic objects at run time.
284 If you do not use either of these options (or use the
286 --no-export-dynamic option to restore the default behavior), the
287 dynamic symbol table will normally contain only those symbols which
288 are referenced by some dynamic object mentioned in the link.
289 If you use "dlopen" to load a dynamic object which needs to refer
291 back to the symbols defined by the program, rather than some other
292 dynamic object, then you will probably need to use this option when
293 linking the program itself.
294 You can also use the dynamic list to control what symbols should be
296 added to the dynamic symbol table if the output format supports it.
297 See the description of --dynamic-list.
298 Note that this option is specific to ELF targeted ports. PE
300 targets support a similar function to export all symbols from a DLL
301 or EXE; see the description of --export-all-symbols below.
302 --export-dynamic-symbol=glob
304 When creating a dynamically linked executable, symbols matching
305 glob will be added to the dynamic symbol table. When creating a
306 shared library, references to symbols matching glob will not be
307 bound to the definitions within the shared library. This option is
308 a no-op when creating a shared library and -Bsymbolic or
309 --dynamic-list are not specified. This option is only meaningful on
310 ELF platforms which support shared libraries.
311 --export-dynamic-symbol-list=file
313 Specify a --export-dynamic-symbol for each pattern in the file.
314 The format of the file is the same as the version node without
315 scope and node name. See VERSION for more information.
316 -EB Link big-endian objects. This affects the default output format.
318 -EL Link little-endian objects. This affects the default output
320 format.
321 -f name
323 --auxiliary=name
324 When creating an ELF shared object, set the internal DT_AUXILIARY
325 field to the specified name. This tells the dynamic linker that
326 the symbol table of the shared object should be used as an
327 auxiliary filter on the symbol table of the shared object name.
328 If you later link a program against this filter object, then, when
330 you run the program, the dynamic linker will see the DT_AUXILIARY
331 field. If the dynamic linker resolves any symbols from the filter
332 object, it will first check whether there is a definition in the
333 shared object name. If there is one, it will be used instead of
334 the definition in the filter object. The shared object name need
335 not exist. Thus the shared object name may be used to provide an
336 alternative implementation of certain functions, perhaps for
337 debugging or for machine-specific performance.
338 This option may be specified more than once. The DT_AUXILIARY
340 entries will be created in the order in which they appear on the
341 command line.
342 -F name
344 --filter=name
345 When creating an ELF shared object, set the internal DT_FILTER
346 field to the specified name. This tells the dynamic linker that
347 the symbol table of the shared object which is being created should
348 be used as a filter on the symbol table of the shared object name.
349 If you later link a program against this filter object, then, when
351 you run the program, the dynamic linker will see the DT_FILTER
352 field. The dynamic linker will resolve symbols according to the
353 symbol table of the filter object as usual, but it will actually
354 link to the definitions found in the shared object name. Thus the
355 filter object can be used to select a subset of the symbols
356 provided by the object name.
357 Some older linkers used the -F option throughout a compilation
359 toolchain for specifying object-file format for both input and
360 output object files. The GNU linker uses other mechanisms for this
361 purpose: the -b, --format, --oformat options, the "TARGET" command
362 in linker scripts, and the "GNUTARGET" environment variable. The
363 GNU linker will ignore the -F option when not creating an ELF
364 shared object.
365 -fini=name
367 When creating an ELF executable or shared object, call NAME when
368 the executable or shared object is unloaded, by setting DT_FINI to
369 the address of the function. By default, the linker uses "_fini"
370 as the function to call.
371 -g Ignored. Provided for compatibility with other tools.
373 -G value
375 --gpsize=value
376 Set the maximum size of objects to be optimized using the GP
377 register to size. This is only meaningful for object file formats
378 such as MIPS ELF that support putting large and small objects into
379 different sections. This is ignored for other object file formats.
380 -h name
382 -soname=name
383 When creating an ELF shared object, set the internal DT_SONAME
384 field to the specified name. When an executable is linked with a
385 shared object which has a DT_SONAME field, then when the executable
386 is run the dynamic linker will attempt to load the shared object
387 specified by the DT_SONAME field rather than the using the file
388 name given to the linker.
389 -i Perform an incremental link (same as option -r).
391 -init=name
393 When creating an ELF executable or shared object, call NAME when
394 the executable or shared object is loaded, by setting DT_INIT to
395 the address of the function. By default, the linker uses "_init"
396 as the function to call.
397 -l namespec
399 --library=namespec
400 Add the archive or object file specified by namespec to the list of
401 files to link. This option may be used any number of times. If
402 namespec is of the form :filename, ld will search the library path
403 for a file called filename, otherwise it will search the library
404 path for a file called libnamespec.a.
405 On systems which support shared libraries, ld may also search for
407 files other than libnamespec.a. Specifically, on ELF and SunOS
408 systems, ld will search a directory for a library called
409 libnamespec.so before searching for one called libnamespec.a. (By
410 convention, a ".so" extension indicates a shared library.) Note
411 that this behavior does not apply to :filename, which always
412 specifies a file called filename.
413 The linker will search an archive only once, at the location where
415 it is specified on the command line. If the archive defines a
416 symbol which was undefined in some object which appeared before the
417 archive on the command line, the linker will include the
418 appropriate file(s) from the archive. However, an undefined symbol
419 in an object appearing later on the command line will not cause the
420 linker to search the archive again.
421 See the -( option for a way to force the linker to search archives
423 multiple times.
424 You may list the same archive multiple times on the command line.
426 This type of archive searching is standard for Unix linkers.
428 However, if you are using ld on AIX, note that it is different from
429 the behaviour of the AIX linker.
430 -L searchdir
432 --library-path=searchdir
433 Add path searchdir to the list of paths that ld will search for
434 archive libraries and ld control scripts. You may use this option
435 any number of times. The directories are searched in the order in
436 which they are specified on the command line. Directories
437 specified on the command line are searched before the default
438 directories. All -L options apply to all -l options, regardless of
439 the order in which the options appear. -L options do not affect
440 how ld searches for a linker script unless -T option is specified.
441 If searchdir begins with "=" or $SYSROOT, then this prefix will be
443 replaced by the sysroot prefix, controlled by the --sysroot option,
444 or specified when the linker is configured.
445 The default set of paths searched (without being specified with -L)
447 depends on which emulation mode ld is using, and in some cases also
448 on how it was configured.
449 The paths can also be specified in a link script with the
451 "SEARCH_DIR" command. Directories specified this way are searched
452 at the point in which the linker script appears in the command
453 line.
454 -m emulation
456 Emulate the emulation linker. You can list the available
457 emulations with the --verbose or -V options.
458 If the -m option is not used, the emulation is taken from the
460 "LDEMULATION" environment variable, if that is defined.
461 Otherwise, the default emulation depends upon how the linker was
463 configured.
464 -M
466 --print-map
467 Print a link map to the standard output. A link map provides
468 information about the link, including the following:
469 · Where object files are mapped into memory.
471 · How common symbols are allocated.
473 · All archive members included in the link, with a mention of the
475 symbol which caused the archive member to be brought in.
476 · The values assigned to symbols.
478 Note - symbols whose values are computed by an expression which
480 involves a reference to a previous value of the same symbol may
481 not have correct result displayed in the link map. This is
482 because the linker discards intermediate results and only
483 retains the final value of an expression. Under such
484 circumstances the linker will display the final value enclosed
485 by square brackets. Thus for example a linker script
486 containing:
487 foo = 1
489 foo = foo * 4
490 foo = foo + 8
491 will produce the following output in the link map if the -M
493 option is used:
494 0x00000001 foo = 0x1
496 [0x0000000c] foo = (foo * 0x4)
497 [0x0000000c] foo = (foo + 0x8)
498 See Expressions for more information about expressions in
500 linker scripts.
501 · How GNU properties are merged.
503 When the linker merges input .note.gnu.property sections into
505 one output .note.gnu.property section, some properties are
506 removed or updated. These actions are reported in the link
507 map. For example:
508 Removed property 0xc0000002 to merge foo.o (0x1) and bar.o (not found)
510 This indicates that property 0xc0000002 is removed from output
512 when merging properties in foo.o, whose property 0xc0000002
513 value is 0x1, and bar.o, which doesn't have property
514 0xc0000002.
515 Updated property 0xc0010001 (0x1) to merge foo.o (0x1) and bar.o (0x1)
517 This indicates that property 0xc0010001 value is updated to 0x1
519 in output when merging properties in foo.o, whose 0xc0010001
520 property value is 0x1, and bar.o, whose 0xc0010001 property
521 value is 0x1.
522 --print-map-discarded
524 --no-print-map-discarded
525 Print (or do not print) the list of discarded and garbage collected
526 sections in the link map. Enabled by default.
527 -n
529 --nmagic
530 Turn off page alignment of sections, and disable linking against
531 shared libraries. If the output format supports Unix style magic
532 numbers, mark the output as "NMAGIC".
533 -N
535 --omagic
536 Set the text and data sections to be readable and writable. Also,
537 do not page-align the data segment, and disable linking against
538 shared libraries. If the output format supports Unix style magic
539 numbers, mark the output as "OMAGIC". Note: Although a writable
540 text section is allowed for PE-COFF targets, it does not conform to
541 the format specification published by Microsoft.
542 --no-omagic
544 This option negates most of the effects of the -N option. It sets
545 the text section to be read-only, and forces the data segment to be
546 page-aligned. Note - this option does not enable linking against
547 shared libraries. Use -Bdynamic for this.
548 -o output
550 --output=output
551 Use output as the name for the program produced by ld; if this
552 option is not specified, the name a.out is used by default. The
553 script command "OUTPUT" can also specify the output file name.
554 --dependency-file=depfile
556 Write a dependency file to depfile. This file contains a rule
557 suitable for "make" describing the output file and all the input
558 files that were read to produce it. The output is similar to the
559 compiler's output with -M -MP. Note that there is no option like
560 the compiler's -MM, to exclude "system files" (which is not a well-
561 specified concept in the linker, unlike "system headers" in the
562 compiler). So the output from --dependency-file is always specific
563 to the exact state of the installation where it was produced, and
564 should not be copied into distributed makefiles without careful
565 editing.
566 -O level
568 If level is a numeric values greater than zero ld optimizes the
569 output. This might take significantly longer and therefore
570 probably should only be enabled for the final binary. At the
571 moment this option only affects ELF shared library generation.
572 Future releases of the linker may make more use of this option.
573 Also currently there is no difference in the linker's behaviour for
574 different non-zero values of this option. Again this may change
575 with future releases.
576 -plugin name
578 Involve a plugin in the linking process. The name parameter is the
579 absolute filename of the plugin. Usually this parameter is
580 automatically added by the complier, when using link time
581 optimization, but users can also add their own plugins if they so
582 wish.
583 Note that the location of the compiler originated plugins is
585 different from the place where the ar, nm and ranlib programs
586 search for their plugins. In order for those commands to make use
587 of a compiler based plugin it must first be copied into the
588 ${libdir}/bfd-plugins directory. All gcc based linker plugins are
589 backward compatible, so it is sufficient to just copy in the newest
590 one.
591 --push-state
593 The --push-state allows to preserve the current state of the flags
594 which govern the input file handling so that they can all be
595 restored with one corresponding --pop-state option.
596 The option which are covered are: -Bdynamic, -Bstatic, -dn, -dy,
598 -call_shared, -non_shared, -static, -N, -n, --whole-archive,
599 --no-whole-archive, -r, -Ur, --copy-dt-needed-entries,
600 --no-copy-dt-needed-entries, --as-needed, --no-as-needed, and -a.
601 One target for this option are specifications for pkg-config. When
603 used with the --libs option all possibly needed libraries are
604 listed and then possibly linked with all the time. It is better to
605 return something as follows:
606 -Wl,--push-state,--as-needed -libone -libtwo -Wl,--pop-state
608 --pop-state
610 Undoes the effect of --push-state, restores the previous values of
611 the flags governing input file handling.
612 -q
614 --emit-relocs
615 Leave relocation sections and contents in fully linked executables.
616 Post link analysis and optimization tools may need this information
617 in order to perform correct modifications of executables. This
618 results in larger executables.
619 This option is currently only supported on ELF platforms.
621 --force-dynamic
623 Force the output file to have dynamic sections. This option is
624 specific to VxWorks targets.
625 -r
627 --relocatable
628 Generate relocatable output---i.e., generate an output file that
629 can in turn serve as input to ld. This is often called partial
630 linking. As a side effect, in environments that support standard
631 Unix magic numbers, this option also sets the output file's magic
632 number to "OMAGIC". If this option is not specified, an absolute
633 file is produced. When linking C++ programs, this option will not
634 resolve references to constructors; to do that, use -Ur.
635 When an input file does not have the same format as the output
637 file, partial linking is only supported if that input file does not
638 contain any relocations. Different output formats can have further
639 restrictions; for example some "a.out"-based formats do not support
640 partial linking with input files in other formats at all.
641 This option does the same thing as -i.
643 -R filename
645 --just-symbols=filename
646 Read symbol names and their addresses from filename, but do not
647 relocate it or include it in the output. This allows your output
648 file to refer symbolically to absolute locations of memory defined
649 in other programs. You may use this option more than once.
650 For compatibility with other ELF linkers, if the -R option is
652 followed by a directory name, rather than a file name, it is
653 treated as the -rpath option.
654 -s
656 --strip-all
657 Omit all symbol information from the output file.
658 -S
660 --strip-debug
661 Omit debugger symbol information (but not all symbols) from the
662 output file.
663 --strip-discarded
665 --no-strip-discarded
666 Omit (or do not omit) global symbols defined in discarded sections.
667 Enabled by default.
668 -t
670 --trace
671 Print the names of the input files as ld processes them. If -t is
672 given twice then members within archives are also printed. -t
673 output is useful to generate a list of all the object files and
674 scripts involved in linking, for example, when packaging files for
675 a linker bug report.
676 -T scriptfile
678 --script=scriptfile
679 Use scriptfile as the linker script. This script replaces ld's
680 default linker script (rather than adding to it), so commandfile
681 must specify everything necessary to describe the output file.
682 If scriptfile does not exist in the current directory, "ld" looks
683 for it in the directories specified by any preceding -L options.
684 Multiple -T options accumulate.
685 -dT scriptfile
687 --default-script=scriptfile
688 Use scriptfile as the default linker script.
689 This option is similar to the --script option except that
691 processing of the script is delayed until after the rest of the
692 command line has been processed. This allows options placed after
693 the --default-script option on the command line to affect the
694 behaviour of the linker script, which can be important when the
695 linker command line cannot be directly controlled by the user. (eg
696 because the command line is being constructed by another tool, such
697 as gcc).
698 -u symbol
700 --undefined=symbol
701 Force symbol to be entered in the output file as an undefined
702 symbol. Doing this may, for example, trigger linking of additional
703 modules from standard libraries. -u may be repeated with different
704 option arguments to enter additional undefined symbols. This
705 option is equivalent to the "EXTERN" linker script command.
706 If this option is being used to force additional modules to be
708 pulled into the link, and if it is an error for the symbol to
709 remain undefined, then the option --require-defined should be used
710 instead.
711 --require-defined=symbol
713 Require that symbol is defined in the output file. This option is
714 the same as option --undefined except that if symbol is not defined
715 in the output file then the linker will issue an error and exit.
716 The same effect can be achieved in a linker script by using
717 "EXTERN", "ASSERT" and "DEFINED" together. This option can be used
718 multiple times to require additional symbols.
719 -Ur For anything other than C++ programs, this option is equivalent to
721 -r: it generates relocatable output---i.e., an output file that can
722 in turn serve as input to ld. When linking C++ programs, -Ur does
723 resolve references to constructors, unlike -r. It does not work to
724 use -Ur on files that were themselves linked with -Ur; once the
725 constructor table has been built, it cannot be added to. Use -Ur
726 only for the last partial link, and -r for the others.
727 --orphan-handling=MODE
729 Control how orphan sections are handled. An orphan section is one
730 not specifically mentioned in a linker script.
731 MODE can have any of the following values:
733 "place"
735 Orphan sections are placed into a suitable output section
736 following the strategy described in Orphan Sections. The
737 option --unique also affects how sections are placed.
738 "discard"
740 All orphan sections are discarded, by placing them in the
741 /DISCARD/ section.
742 "warn"
744 The linker will place the orphan section as for "place" and
745 also issue a warning.
746 "error"
748 The linker will exit with an error if any orphan section is
749 found.
750 The default if --orphan-handling is not given is "place".
752 --unique[=SECTION]
754 Creates a separate output section for every input section matching
755 SECTION, or if the optional wildcard SECTION argument is missing,
756 for every orphan input section. An orphan section is one not
757 specifically mentioned in a linker script. You may use this option
758 multiple times on the command line; It prevents the normal merging
759 of input sections with the same name, overriding output section
760 assignments in a linker script.
761 -v
763 --version
764 -V Display the version number for ld. The -V option also lists the
765 supported emulations.
766 -x
768 --discard-all
769 Delete all local symbols.
770 -X
772 --discard-locals
773 Delete all temporary local symbols. (These symbols start with
774 system-specific local label prefixes, typically .L for ELF systems
775 or L for traditional a.out systems.)
776 -y symbol
778 --trace-symbol=symbol
779 Print the name of each linked file in which symbol appears. This
780 option may be given any number of times. On many systems it is
781 necessary to prepend an underscore.
782 This option is useful when you have an undefined symbol in your
784 link but don't know where the reference is coming from.
785 -Y path
787 Add path to the default library search path. This option exists
788 for Solaris compatibility.
789 -z keyword
791 The recognized keywords are:
792 bndplt
794 Always generate BND prefix in PLT entries. Supported for
795 Linux/x86_64.
796 call-nop=prefix-addr
798 call-nop=suffix-nop
799 call-nop=prefix-byte
800 call-nop=suffix-byte
801 Specify the 1-byte "NOP" padding when transforming indirect
802 call to a locally defined function, foo, via its GOT slot.
803 call-nop=prefix-addr generates "0x67 call foo".
804 call-nop=suffix-nop generates "call foo 0x90".
805 call-nop=prefix-byte generates "byte call foo".
806 call-nop=suffix-byte generates "call foo byte". Supported for
807 i386 and x86_64.
808 cet-report=none
810 cet-report=warning
811 cet-report=error
812 Specify how to report the missing
813 GNU_PROPERTY_X86_FEATURE_1_IBT and
814 GNU_PROPERTY_X86_FEATURE_1_SHSTK properties in input
815 .note.gnu.property section. cet-report=none, which is the
816 default, will make the linker not report missing properties in
817 input files. cet-report=warning will make the linker issue a
818 warning for missing properties in input files.
819 cet-report=error will make the linker issue an error for
820 missing properties in input files. Note that ibt will turn off
821 the missing GNU_PROPERTY_X86_FEATURE_1_IBT property report and
822 shstk will turn off the missing
823 GNU_PROPERTY_X86_FEATURE_1_SHSTK property report. Supported
824 for Linux/i386 and Linux/x86_64.
825 combreloc
827 nocombreloc
828 Combine multiple dynamic relocation sections and sort to
829 improve dynamic symbol lookup caching. Do not do this if
830 nocombreloc.
831 common
833 nocommon
834 Generate common symbols with STT_COMMON type during a
835 relocatable link. Use STT_OBJECT type if nocommon.
836 common-page-size=value
838 Set the page size most commonly used to value. Memory image
839 layout will be optimized to minimize memory pages if the system
840 is using pages of this size.
841 defs
843 Report unresolved symbol references from regular object files.
844 This is done even if the linker is creating a non-symbolic
845 shared library. This option is the inverse of -z undefs.
846 dynamic-undefined-weak
848 nodynamic-undefined-weak
849 Make undefined weak symbols dynamic when building a dynamic
850 object, if they are referenced from a regular object file and
851 not forced local by symbol visibility or versioning. Do not
852 make them dynamic if nodynamic-undefined-weak. If neither
853 option is given, a target may default to either option being in
854 force, or make some other selection of undefined weak symbols
855 dynamic. Not all targets support these options.
856 execstack
858 Marks the object as requiring executable stack.
859 global
861 This option is only meaningful when building a shared object.
862 It makes the symbols defined by this shared object available
863 for symbol resolution of subsequently loaded libraries.
864 globalaudit
866 This option is only meaningful when building a dynamic
867 executable. This option marks the executable as requiring
868 global auditing by setting the "DF_1_GLOBAUDIT" bit in the
869 "DT_FLAGS_1" dynamic tag. Global auditing requires that any
870 auditing library defined via the --depaudit or -P command-line
871 options be run for all dynamic objects loaded by the
872 application.
873 ibtplt
875 Generate Intel Indirect Branch Tracking (IBT) enabled PLT
876 entries. Supported for Linux/i386 and Linux/x86_64.
877 ibt Generate GNU_PROPERTY_X86_FEATURE_1_IBT in .note.gnu.property
879 section to indicate compatibility with IBT. This also implies
880 ibtplt. Supported for Linux/i386 and Linux/x86_64.
881 initfirst
883 This option is only meaningful when building a shared object.
884 It marks the object so that its runtime initialization will
885 occur before the runtime initialization of any other objects
886 brought into the process at the same time. Similarly the
887 runtime finalization of the object will occur after the runtime
888 finalization of any other objects.
889 interpose
891 Specify that the dynamic loader should modify its symbol search
892 order so that symbols in this shared library interpose all
893 other shared libraries not so marked.
894 lazy
896 When generating an executable or shared library, mark it to
897 tell the dynamic linker to defer function call resolution to
898 the point when the function is called (lazy binding), rather
899 than at load time. Lazy binding is the default.
900 loadfltr
902 Specify that the object's filters be processed immediately at
903 runtime.
904 max-page-size=value
906 Set the maximum memory page size supported to value.
907 muldefs
909 Allow multiple definitions.
910 nocopyreloc
912 Disable linker generated .dynbss variables used in place of
913 variables defined in shared libraries. May result in dynamic
914 text relocations.
915 nodefaultlib
917 Specify that the dynamic loader search for dependencies of this
918 object should ignore any default library search paths.
919 nodelete
921 Specify that the object shouldn't be unloaded at runtime.
922 nodlopen
924 Specify that the object is not available to "dlopen".
925 nodump
927 Specify that the object can not be dumped by "dldump".
928 noexecstack
930 Marks the object as not requiring executable stack.
931 noextern-protected-data
933 Don't treat protected data symbols as external when building a
934 shared library. This option overrides the linker backend
935 default. It can be used to work around incorrect relocations
936 against protected data symbols generated by compiler. Updates
937 on protected data symbols by another module aren't visible to
938 the resulting shared library. Supported for i386 and x86-64.
939 noreloc-overflow
941 Disable relocation overflow check. This can be used to disable
942 relocation overflow check if there will be no dynamic
943 relocation overflow at run-time. Supported for x86_64.
944 now When generating an executable or shared library, mark it to
946 tell the dynamic linker to resolve all symbols when the program
947 is started, or when the shared library is loaded by dlopen,
948 instead of deferring function call resolution to the point when
949 the function is first called.
950 origin
952 Specify that the object requires $ORIGIN handling in paths.
953 relro
955 norelro
956 Create an ELF "PT_GNU_RELRO" segment header in the object.
957 This specifies a memory segment that should be made read-only
958 after relocation, if supported. Specifying common-page-size
959 smaller than the system page size will render this protection
960 ineffective. Don't create an ELF "PT_GNU_RELRO" segment if
961 norelro.
962 separate-code
964 noseparate-code
965 Create separate code "PT_LOAD" segment header in the object.
966 This specifies a memory segment that should contain only
967 instructions and must be in wholly disjoint pages from any
968 other data. Don't create separate code "PT_LOAD" segment if
969 noseparate-code is used.
970 shstk
972 Generate GNU_PROPERTY_X86_FEATURE_1_SHSTK in .note.gnu.property
973 section to indicate compatibility with Intel Shadow Stack.
974 Supported for Linux/i386 and Linux/x86_64.
975 stack-size=value
977 Specify a stack size for an ELF "PT_GNU_STACK" segment.
978 Specifying zero will override any default non-zero sized
979 "PT_GNU_STACK" segment creation.
980 start-stop-visibility=value
982 Specify the ELF symbol visibility for synthesized
983 "__start_SECNAME" and "__stop_SECNAME" symbols. value must be
984 exactly default, internal, hidden, or protected. If no -z
985 start-stop-visibility option is given, protected is used for
986 compatibility with historical practice. However, it's highly
987 recommended to use -z start-stop-visibility=hidden in new
988 programs and shared libraries so that these symbols are not
989 exported between shared objects, which is not usually what's
990 intended.
991 text
993 notext
994 textoff
995 Report an error if DT_TEXTREL is set, i.e., if the position-
996 independent or shared object has dynamic relocations in read-
997 only sections. Don't report an error if notext or textoff.
998 undefs
1000 Do not report unresolved symbol references from regular object
1001 files, either when creating an executable, or when creating a
1002 shared library. This option is the inverse of -z defs.
1003 Other keywords are ignored for Solaris compatibility.
1005 -( archives -)
1007 --start-group archives --end-group
1008 The archives should be a list of archive files. They may be either
1009 explicit file names, or -l options.
1010 The specified archives are searched repeatedly until no new
1012 undefined references are created. Normally, an archive is searched
1013 only once in the order that it is specified on the command line.
1014 If a symbol in that archive is needed to resolve an undefined
1015 symbol referred to by an object in an archive that appears later on
1016 the command line, the linker would not be able to resolve that
1017 reference. By grouping the archives, they will all be searched
1018 repeatedly until all possible references are resolved.
1019 Using this option has a significant performance cost. It is best
1021 to use it only when there are unavoidable circular references
1022 between two or more archives.
1023 --accept-unknown-input-arch
1025 --no-accept-unknown-input-arch
1026 Tells the linker to accept input files whose architecture cannot be
1027 recognised. The assumption is that the user knows what they are
1028 doing and deliberately wants to link in these unknown input files.
1029 This was the default behaviour of the linker, before release 2.14.
1030 The default behaviour from release 2.14 onwards is to reject such
1031 input files, and so the --accept-unknown-input-arch option has been
1032 added to restore the old behaviour.
1033 --as-needed
1035 --no-as-needed
1036 This option affects ELF DT_NEEDED tags for dynamic libraries
1037 mentioned on the command line after the --as-needed option.
1038 Normally the linker will add a DT_NEEDED tag for each dynamic
1039 library mentioned on the command line, regardless of whether the
1040 library is actually needed or not. --as-needed causes a DT_NEEDED
1041 tag to only be emitted for a library that at that point in the link
1042 satisfies a non-weak undefined symbol reference from a regular
1043 object file or, if the library is not found in the DT_NEEDED lists
1044 of other needed libraries, a non-weak undefined symbol reference
1045 from another needed dynamic library. Object files or libraries
1046 appearing on the command line after the library in question do not
1047 affect whether the library is seen as needed. This is similar to
1048 the rules for extraction of object files from archives.
1049 --no-as-needed restores the default behaviour.
1050 --add-needed
1052 --no-add-needed
1053 These two options have been deprecated because of the similarity of
1054 their names to the --as-needed and --no-as-needed options. They
1055 have been replaced by --copy-dt-needed-entries and
1056 --no-copy-dt-needed-entries.
1057 -assert keyword
1059 This option is ignored for SunOS compatibility.
1060 -Bdynamic
1062 -dy
1063 -call_shared
1064 Link against dynamic libraries. This is only meaningful on
1065 platforms for which shared libraries are supported. This option is
1066 normally the default on such platforms. The different variants of
1067 this option are for compatibility with various systems. You may
1068 use this option multiple times on the command line: it affects
1069 library searching for -l options which follow it.
1070 -Bgroup
1072 Set the "DF_1_GROUP" flag in the "DT_FLAGS_1" entry in the dynamic
1073 section. This causes the runtime linker to handle lookups in this
1074 object and its dependencies to be performed only inside the group.
1075 --unresolved-symbols=report-all is implied. This option is only
1076 meaningful on ELF platforms which support shared libraries.
1077 -Bstatic
1079 -dn
1080 -non_shared
1081 -static
1082 Do not link against shared libraries. This is only meaningful on
1083 platforms for which shared libraries are supported. The different
1084 variants of this option are for compatibility with various systems.
1085 You may use this option multiple times on the command line: it
1086 affects library searching for -l options which follow it. This
1087 option also implies --unresolved-symbols=report-all. This option
1088 can be used with -shared. Doing so means that a shared library is
1089 being created but that all of the library's external references
1090 must be resolved by pulling in entries from static libraries.
1091 -Bsymbolic
1093 When creating a shared library, bind references to global symbols
1094 to the definition within the shared library, if any. Normally, it
1095 is possible for a program linked against a shared library to
1096 override the definition within the shared library. This option is
1097 only meaningful on ELF platforms which support shared libraries.
1098 -Bsymbolic-functions
1100 When creating a shared library, bind references to global function
1101 symbols to the definition within the shared library, if any. This
1102 option is only meaningful on ELF platforms which support shared
1103 libraries.
1104 --dynamic-list=dynamic-list-file
1106 Specify the name of a dynamic list file to the linker. This is
1107 typically used when creating shared libraries to specify a list of
1108 global symbols whose references shouldn't be bound to the
1109 definition within the shared library, or creating dynamically
1110 linked executables to specify a list of symbols which should be
1111 added to the symbol table in the executable. This option is only
1112 meaningful on ELF platforms which support shared libraries.
1113 The format of the dynamic list is the same as the version node
1115 without scope and node name. See VERSION for more information.
1116 --dynamic-list-data
1118 Include all global data symbols to the dynamic list.
1119 --dynamic-list-cpp-new
1121 Provide the builtin dynamic list for C++ operator new and delete.
1122 It is mainly useful for building shared libstdc++.
1123 --dynamic-list-cpp-typeinfo
1125 Provide the builtin dynamic list for C++ runtime type
1126 identification.
1127 --check-sections
1129 --no-check-sections
1130 Asks the linker not to check section addresses after they have been
1131 assigned to see if there are any overlaps. Normally the linker
1132 will perform this check, and if it finds any overlaps it will
1133 produce suitable error messages. The linker does know about, and
1134 does make allowances for sections in overlays. The default
1135 behaviour can be restored by using the command-line switch
1136 --check-sections. Section overlap is not usually checked for
1137 relocatable links. You can force checking in that case by using
1138 the --check-sections option.
1139 --copy-dt-needed-entries
1141 --no-copy-dt-needed-entries
1142 This option affects the treatment of dynamic libraries referred to
1143 by DT_NEEDED tags inside ELF dynamic libraries mentioned on the
1144 command line. Normally the linker won't add a DT_NEEDED tag to the
1145 output binary for each library mentioned in a DT_NEEDED tag in an
1146 input dynamic library. With --copy-dt-needed-entries specified on
1147 the command line however any dynamic libraries that follow it will
1148 have their DT_NEEDED entries added. The default behaviour can be
1149 restored with --no-copy-dt-needed-entries.
1150 This option also has an effect on the resolution of symbols in
1152 dynamic libraries. With --copy-dt-needed-entries dynamic libraries
1153 mentioned on the command line will be recursively searched,
1154 following their DT_NEEDED tags to other libraries, in order to
1155 resolve symbols required by the output binary. With the default
1156 setting however the searching of dynamic libraries that follow it
1157 will stop with the dynamic library itself. No DT_NEEDED links will
1158 be traversed to resolve symbols.
1159 --cref
1161 Output a cross reference table. If a linker map file is being
1162 generated, the cross reference table is printed to the map file.
1163 Otherwise, it is printed on the standard output.
1164 The format of the table is intentionally simple, so that it may be
1166 easily processed by a script if necessary. The symbols are printed
1167 out, sorted by name. For each symbol, a list of file names is
1168 given. If the symbol is defined, the first file listed is the
1169 location of the definition. If the symbol is defined as a common
1170 value then any files where this happens appear next. Finally any
1171 files that reference the symbol are listed.
1172 --no-define-common
1174 This option inhibits the assignment of addresses to common symbols.
1175 The script command "INHIBIT_COMMON_ALLOCATION" has the same effect.
1176 The --no-define-common option allows decoupling the decision to
1178 assign addresses to Common symbols from the choice of the output
1179 file type; otherwise a non-Relocatable output type forces assigning
1180 addresses to Common symbols. Using --no-define-common allows
1181 Common symbols that are referenced from a shared library to be
1182 assigned addresses only in the main program. This eliminates the
1183 unused duplicate space in the shared library, and also prevents any
1184 possible confusion over resolving to the wrong duplicate when there
1185 are many dynamic modules with specialized search paths for runtime
1186 symbol resolution.
1187 --force-group-allocation
1189 This option causes the linker to place section group members like
1190 normal input sections, and to delete the section groups. This is
1191 the default behaviour for a final link but this option can be used
1192 to change the behaviour of a relocatable link (-r). The script
1193 command "FORCE_GROUP_ALLOCATION" has the same effect.
1194 --defsym=symbol=expression
1196 Create a global symbol in the output file, containing the absolute
1197 address given by expression. You may use this option as many times
1198 as necessary to define multiple symbols in the command line. A
1199 limited form of arithmetic is supported for the expression in this
1200 context: you may give a hexadecimal constant or the name of an
1201 existing symbol, or use "+" and "-" to add or subtract hexadecimal
1202 constants or symbols. If you need more elaborate expressions,
1203 consider using the linker command language from a script. Note:
1204 there should be no white space between symbol, the equals sign
1205 ("="), and expression.
1206 --demangle[=style]
1208 --no-demangle
1209 These options control whether to demangle symbol names in error
1210 messages and other output. When the linker is told to demangle, it
1211 tries to present symbol names in a readable fashion: it strips
1212 leading underscores if they are used by the object file format, and
1213 converts C++ mangled symbol names into user readable names.
1214 Different compilers have different mangling styles. The optional
1215 demangling style argument can be used to choose an appropriate
1216 demangling style for your compiler. The linker will demangle by
1217 default unless the environment variable COLLECT_NO_DEMANGLE is set.
1218 These options may be used to override the default.
1219 -Ifile
1221 --dynamic-linker=file
1222 Set the name of the dynamic linker. This is only meaningful when
1223 generating dynamically linked ELF executables. The default dynamic
1224 linker is normally correct; don't use this unless you know what you
1225 are doing.
1226 --no-dynamic-linker
1228 When producing an executable file, omit the request for a dynamic
1229 linker to be used at load-time. This is only meaningful for ELF
1230 executables that contain dynamic relocations, and usually requires
1231 entry point code that is capable of processing these relocations.
1232 --embedded-relocs
1234 This option is similar to the --emit-relocs option except that the
1235 relocs are stored in a target-specific section. This option is
1236 only supported by the BFIN, CR16 and M68K targets.
1237 --disable-multiple-abs-defs
1239 Do not allow multiple definitions with symbols included in filename
1240 invoked by -R or --just-symbols
1241 --fatal-warnings
1243 --no-fatal-warnings
1244 Treat all warnings as errors. The default behaviour can be
1245 restored with the option --no-fatal-warnings.
1246 --force-exe-suffix
1248 Make sure that an output file has a .exe suffix.
1249 If a successfully built fully linked output file does not have a
1251 ".exe" or ".dll" suffix, this option forces the linker to copy the
1252 output file to one of the same name with a ".exe" suffix. This
1253 option is useful when using unmodified Unix makefiles on a
1254 Microsoft Windows host, since some versions of Windows won't run an
1255 image unless it ends in a ".exe" suffix.
1256 --gc-sections
1258 --no-gc-sections
1259 Enable garbage collection of unused input sections. It is ignored
1260 on targets that do not support this option. The default behaviour
1261 (of not performing this garbage collection) can be restored by
1262 specifying --no-gc-sections on the command line. Note that garbage
1263 collection for COFF and PE format targets is supported, but the
1264 implementation is currently considered to be experimental.
1265 --gc-sections decides which input sections are used by examining
1267 symbols and relocations. The section containing the entry symbol
1268 and all sections containing symbols undefined on the command-line
1269 will be kept, as will sections containing symbols referenced by
1270 dynamic objects. Note that when building shared libraries, the
1271 linker must assume that any visible symbol is referenced. Once
1272 this initial set of sections has been determined, the linker
1273 recursively marks as used any section referenced by their
1274 relocations. See --entry, --undefined, and --gc-keep-exported.
1275 This option can be set when doing a partial link (enabled with
1277 option -r). In this case the root of symbols kept must be
1278 explicitly specified either by one of the options --entry,
1279 --undefined, or --gc-keep-exported or by a "ENTRY" command in the
1280 linker script.
1281 --print-gc-sections
1283 --no-print-gc-sections
1284 List all sections removed by garbage collection. The listing is
1285 printed on stderr. This option is only effective if garbage
1286 collection has been enabled via the --gc-sections) option. The
1287 default behaviour (of not listing the sections that are removed)
1288 can be restored by specifying --no-print-gc-sections on the command
1289 line.
1290 --gc-keep-exported
1292 When --gc-sections is enabled, this option prevents garbage
1293 collection of unused input sections that contain global symbols
1294 having default or protected visibility. This option is intended to
1295 be used for executables where unreferenced sections would otherwise
1296 be garbage collected regardless of the external visibility of
1297 contained symbols. Note that this option has no effect when
1298 linking shared objects since it is already the default behaviour.
1299 This option is only supported for ELF format targets.
1300 --print-output-format
1302 Print the name of the default output format (perhaps influenced by
1303 other command-line options). This is the string that would appear
1304 in an "OUTPUT_FORMAT" linker script command.
1305 --print-memory-usage
1307 Print used size, total size and used size of memory regions created
1308 with the MEMORY command. This is useful on embedded targets to
1309 have a quick view of amount of free memory. The format of the
1310 output has one headline and one line per region. It is both human
1311 readable and easily parsable by tools. Here is an example of an
1312 output:
1313 Memory region Used Size Region Size %age Used
1315 ROM: 256 KB 1 MB 25.00%
1316 RAM: 32 B 2 GB 0.00%
1317 --help
1319 Print a summary of the command-line options on the standard output
1320 and exit.
1321 --target-help
1323 Print a summary of all target-specific options on the standard
1324 output and exit.
1325 -Map=mapfile
1327 Print a link map to the file mapfile. See the description of the
1328 -M option, above. Specifying a directory as mapfile causes the
1329 linker map to be written into a file inside the directory. The
1330 name of the file is based upon the output filename with ".map"
1331 appended.
1332 --no-keep-memory
1334 ld normally optimizes for speed over memory usage by caching the
1335 symbol tables of input files in memory. This option tells ld to
1336 instead optimize for memory usage, by rereading the symbol tables
1337 as necessary. This may be required if ld runs out of memory space
1338 while linking a large executable.
1339 --no-undefined
1341 -z defs
1342 Report unresolved symbol references from regular object files.
1343 This is done even if the linker is creating a non-symbolic shared
1344 library. The switch --[no-]allow-shlib-undefined controls the
1345 behaviour for reporting unresolved references found in shared
1346 libraries being linked in.
1347 The effects of this option can be reverted by using "-z undefs".
1349 --allow-multiple-definition
1351 -z muldefs
1352 Normally when a symbol is defined multiple times, the linker will
1353 report a fatal error. These options allow multiple definitions and
1354 the first definition will be used.
1355 --allow-shlib-undefined
1357 --no-allow-shlib-undefined
1358 Allows or disallows undefined symbols in shared libraries. This
1359 switch is similar to --no-undefined except that it determines the
1360 behaviour when the undefined symbols are in a shared library rather
1361 than a regular object file. It does not affect how undefined
1362 symbols in regular object files are handled.
1363 The default behaviour is to report errors for any undefined symbols
1365 referenced in shared libraries if the linker is being used to
1366 create an executable, but to allow them if the linker is being used
1367 to create a shared library.
1368 The reasons for allowing undefined symbol references in shared
1370 libraries specified at link time are that:
1371 · A shared library specified at link time may not be the same as
1373 the one that is available at load time, so the symbol might
1374 actually be resolvable at load time.
1375 · There are some operating systems, eg BeOS and HPPA, where
1377 undefined symbols in shared libraries are normal.
1378 The BeOS kernel for example patches shared libraries at load
1380 time to select whichever function is most appropriate for the
1381 current architecture. This is used, for example, to
1382 dynamically select an appropriate memset function.
1383 --no-undefined-version
1385 Normally when a symbol has an undefined version, the linker will
1386 ignore it. This option disallows symbols with undefined version and
1387 a fatal error will be issued instead.
1388 --default-symver
1390 Create and use a default symbol version (the soname) for
1391 unversioned exported symbols.
1392 --default-imported-symver
1394 Create and use a default symbol version (the soname) for
1395 unversioned imported symbols.
1396 --no-warn-mismatch
1398 Normally ld will give an error if you try to link together input
1399 files that are mismatched for some reason, perhaps because they
1400 have been compiled for different processors or for different
1401 endiannesses. This option tells ld that it should silently permit
1402 such possible errors. This option should only be used with care,
1403 in cases when you have taken some special action that ensures that
1404 the linker errors are inappropriate.
1405 --no-warn-search-mismatch
1407 Normally ld will give a warning if it finds an incompatible library
1408 during a library search. This option silences the warning.
1409 --no-whole-archive
1411 Turn off the effect of the --whole-archive option for subsequent
1412 archive files.
1413 --noinhibit-exec
1415 Retain the executable output file whenever it is still usable.
1416 Normally, the linker will not produce an output file if it
1417 encounters errors during the link process; it exits without writing
1418 an output file when it issues any error whatsoever.
1419 -nostdlib
1421 Only search library directories explicitly specified on the command
1422 line. Library directories specified in linker scripts (including
1423 linker scripts specified on the command line) are ignored.
1424 --oformat=output-format
1426 ld may be configured to support more than one kind of object file.
1427 If your ld is configured this way, you can use the --oformat option
1428 to specify the binary format for the output object file. Even when
1429 ld is configured to support alternative object formats, you don't
1430 usually need to specify this, as ld should be configured to produce
1431 as a default output format the most usual format on each machine.
1432 output-format is a text string, the name of a particular format
1433 supported by the BFD libraries. (You can list the available binary
1434 formats with objdump -i.) The script command "OUTPUT_FORMAT" can
1435 also specify the output format, but this option overrides it.
1436 --out-implib file
1438 Create an import library in file corresponding to the executable
1439 the linker is generating (eg. a DLL or ELF program). This import
1440 library (which should be called "*.dll.a" or "*.a" for DLLs) may be
1441 used to link clients against the generated executable; this
1442 behaviour makes it possible to skip a separate import library
1443 creation step (eg. "dlltool" for DLLs). This option is only
1444 available for the i386 PE and ELF targetted ports of the linker.
1445 -pie
1447 --pic-executable
1448 Create a position independent executable. This is currently only
1449 supported on ELF platforms. Position independent executables are
1450 similar to shared libraries in that they are relocated by the
1451 dynamic linker to the virtual address the OS chooses for them
1452 (which can vary between invocations). Like normal dynamically
1453 linked executables they can be executed and symbols defined in the
1454 executable cannot be overridden by shared libraries.
1455 -qmagic
1457 This option is ignored for Linux compatibility.
1458 -Qy This option is ignored for SVR4 compatibility.
1460 --relax
1462 --no-relax
1463 An option with machine dependent effects. This option is only
1464 supported on a few targets.
1465 On some platforms the --relax option performs target-specific,
1467 global optimizations that become possible when the linker resolves
1468 addressing in the program, such as relaxing address modes,
1469 synthesizing new instructions, selecting shorter version of current
1470 instructions, and combining constant values.
1471 On some platforms these link time global optimizations may make
1473 symbolic debugging of the resulting executable impossible. This is
1474 known to be the case for the Matsushita MN10200 and MN10300 family
1475 of processors.
1476 On platforms where this is not supported, --relax is accepted, but
1478 ignored.
1479 On platforms where --relax is accepted the option --no-relax can be
1481 used to disable the feature.
1482 --retain-symbols-file=filename
1484 Retain only the symbols listed in the file filename, discarding all
1485 others. filename is simply a flat file, with one symbol name per
1486 line. This option is especially useful in environments (such as
1487 VxWorks) where a large global symbol table is accumulated
1488 gradually, to conserve run-time memory.
1489 --retain-symbols-file does not discard undefined symbols, or
1491 symbols needed for relocations.
1492 You may only specify --retain-symbols-file once in the command
1494 line. It overrides -s and -S.
1495 -rpath=dir
1497 Add a directory to the runtime library search path. This is used
1498 when linking an ELF executable with shared objects. All -rpath
1499 arguments are concatenated and passed to the runtime linker, which
1500 uses them to locate shared objects at runtime.
1501 The -rpath option is also used when locating shared objects which
1503 are needed by shared objects explicitly included in the link; see
1504 the description of the -rpath-link option. Searching -rpath in
1505 this way is only supported by native linkers and cross linkers
1506 which have been configured with the --with-sysroot option.
1507 If -rpath is not used when linking an ELF executable, the contents
1509 of the environment variable "LD_RUN_PATH" will be used if it is
1510 defined.
1511 The -rpath option may also be used on SunOS. By default, on SunOS,
1513 the linker will form a runtime search path out of all the -L
1514 options it is given. If a -rpath option is used, the runtime
1515 search path will be formed exclusively using the -rpath options,
1516 ignoring the -L options. This can be useful when using gcc, which
1517 adds many -L options which may be on NFS mounted file systems.
1518 For compatibility with other ELF linkers, if the -R option is
1520 followed by a directory name, rather than a file name, it is
1521 treated as the -rpath option.
1522 -rpath-link=dir
1524 When using ELF or SunOS, one shared library may require another.
1525 This happens when an "ld -shared" link includes a shared library as
1526 one of the input files.
1527 When the linker encounters such a dependency when doing a non-
1529 shared, non-relocatable link, it will automatically try to locate
1530 the required shared library and include it in the link, if it is
1531 not included explicitly. In such a case, the -rpath-link option
1532 specifies the first set of directories to search. The -rpath-link
1533 option may specify a sequence of directory names either by
1534 specifying a list of names separated by colons, or by appearing
1535 multiple times.
1536 The tokens $ORIGIN and $LIB can appear in these search directories.
1538 They will be replaced by the full path to the directory containing
1539 the program or shared object in the case of $ORIGIN and either lib
1540 - for 32-bit binaries - or lib64 - for 64-bit binaries - in the
1541 case of $LIB.
1542 The alternative form of these tokens - ${ORIGIN} and ${LIB} can
1544 also be used. The token $PLATFORM is not supported.
1545 This option should be used with caution as it overrides the search
1547 path that may have been hard compiled into a shared library. In
1548 such a case it is possible to use unintentionally a different
1549 search path than the runtime linker would do.
1550 The linker uses the following search paths to locate required
1552 shared libraries:
1553 1. Any directories specified by -rpath-link options.
1555 2. Any directories specified by -rpath options. The difference
1557 between -rpath and -rpath-link is that directories specified by
1558 -rpath options are included in the executable and used at
1559 runtime, whereas the -rpath-link option is only effective at
1560 link time. Searching -rpath in this way is only supported by
1561 native linkers and cross linkers which have been configured
1562 with the --with-sysroot option.
1563 3. On an ELF system, for native linkers, if the -rpath and
1565 -rpath-link options were not used, search the contents of the
1566 environment variable "LD_RUN_PATH".
1567 4. On SunOS, if the -rpath option was not used, search any
1569 directories specified using -L options.
1570 5. For a native linker, search the contents of the environment
1572 variable "LD_LIBRARY_PATH".
1573 6. For a native ELF linker, the directories in "DT_RUNPATH" or
1575 "DT_RPATH" of a shared library are searched for shared
1576 libraries needed by it. The "DT_RPATH" entries are ignored if
1577 "DT_RUNPATH" entries exist.
1578 7. The default directories, normally /lib and /usr/lib.
1580 8. For a linker for a Linux system, if the file /etc/ld.so.conf
1582 exists, the list of directories found in that file. Note: the
1583 path to this file is prefixed with the "sysroot" value, if that
1584 is defined, and then any "prefix" string if the linker was
1585 configured with the --prefix=<path> option.
1586 9. For a native linker on a FreeBSD system, any directories
1588 specified by the "_PATH_ELF_HINTS" macro defined in the
1589 elf-hints.h header file.
1590 10. Any directories specifed by a "SEARCH_DIR" command in the
1592 linker script being used.
1593 If the required shared library is not found, the linker will issue
1595 a warning and continue with the link.
1596 -shared
1598 -Bshareable
1599 Create a shared library. This is currently only supported on ELF,
1600 XCOFF and SunOS platforms. On SunOS, the linker will automatically
1601 create a shared library if the -e option is not used and there are
1602 undefined symbols in the link.
1603 --sort-common
1605 --sort-common=ascending
1606 --sort-common=descending
1607 This option tells ld to sort the common symbols by alignment in
1608 ascending or descending order when it places them in the
1609 appropriate output sections. The symbol alignments considered are
1610 sixteen-byte or larger, eight-byte, four-byte, two-byte, and one-
1611 byte. This is to prevent gaps between symbols due to alignment
1612 constraints. If no sorting order is specified, then descending
1613 order is assumed.
1614 --sort-section=name
1616 This option will apply "SORT_BY_NAME" to all wildcard section
1617 patterns in the linker script.
1618 --sort-section=alignment
1620 This option will apply "SORT_BY_ALIGNMENT" to all wildcard section
1621 patterns in the linker script.
1622 --spare-dynamic-tags=count
1624 This option specifies the number of empty slots to leave in the
1625 .dynamic section of ELF shared objects. Empty slots may be needed
1626 by post processing tools, such as the prelinker. The default is 5.
1627 --split-by-file[=size]
1629 Similar to --split-by-reloc but creates a new output section for
1630 each input file when size is reached. size defaults to a size of 1
1631 if not given.
1632 --split-by-reloc[=count]
1634 Tries to creates extra sections in the output file so that no
1635 single output section in the file contains more than count
1636 relocations. This is useful when generating huge relocatable files
1637 for downloading into certain real time kernels with the COFF object
1638 file format; since COFF cannot represent more than 65535
1639 relocations in a single section. Note that this will fail to work
1640 with object file formats which do not support arbitrary sections.
1641 The linker will not split up individual input sections for
1642 redistribution, so if a single input section contains more than
1643 count relocations one output section will contain that many
1644 relocations. count defaults to a value of 32768.
1645 --stats
1647 Compute and display statistics about the operation of the linker,
1648 such as execution time and memory usage.
1649 --sysroot=directory
1651 Use directory as the location of the sysroot, overriding the
1652 configure-time default. This option is only supported by linkers
1653 that were configured using --with-sysroot.
1654 --task-link
1656 This is used by COFF/PE based targets to create a task-linked
1657 object file where all of the global symbols have been converted to
1658 statics.
1659 --traditional-format
1661 For some targets, the output of ld is different in some ways from
1662 the output of some existing linker. This switch requests ld to use
1663 the traditional format instead.
1664 For example, on SunOS, ld combines duplicate entries in the symbol
1666 string table. This can reduce the size of an output file with full
1667 debugging information by over 30 percent. Unfortunately, the SunOS
1668 "dbx" program can not read the resulting program ("gdb" has no
1669 trouble). The --traditional-format switch tells ld to not combine
1670 duplicate entries.
1671 --section-start=sectionname=org
1673 Locate a section in the output file at the absolute address given
1674 by org. You may use this option as many times as necessary to
1675 locate multiple sections in the command line. org must be a single
1676 hexadecimal integer; for compatibility with other linkers, you may
1677 omit the leading 0x usually associated with hexadecimal values.
1678 Note: there should be no white space between sectionname, the
1679 equals sign ("="), and org.
1680 -Tbss=org
1682 -Tdata=org
1683 -Ttext=org
1684 Same as --section-start, with ".bss", ".data" or ".text" as the
1685 sectionname.
1686 -Ttext-segment=org
1688 When creating an ELF executable, it will set the address of the
1689 first byte of the text segment.
1690 -Trodata-segment=org
1692 When creating an ELF executable or shared object for a target where
1693 the read-only data is in its own segment separate from the
1694 executable text, it will set the address of the first byte of the
1695 read-only data segment.
1696 -Tldata-segment=org
1698 When creating an ELF executable or shared object for x86-64 medium
1699 memory model, it will set the address of the first byte of the
1700 ldata segment.
1701 --unresolved-symbols=method
1703 Determine how to handle unresolved symbols. There are four
1704 possible values for method:
1705 ignore-all
1707 Do not report any unresolved symbols.
1708 report-all
1710 Report all unresolved symbols. This is the default.
1711 ignore-in-object-files
1713 Report unresolved symbols that are contained in shared
1714 libraries, but ignore them if they come from regular object
1715 files.
1716 ignore-in-shared-libs
1718 Report unresolved symbols that come from regular object files,
1719 but ignore them if they come from shared libraries. This can
1720 be useful when creating a dynamic binary and it is known that
1721 all the shared libraries that it should be referencing are
1722 included on the linker's command line.
1723 The behaviour for shared libraries on their own can also be
1725 controlled by the --[no-]allow-shlib-undefined option.
1726 Normally the linker will generate an error message for each
1728 reported unresolved symbol but the option --warn-unresolved-symbols
1729 can change this to a warning.
1730 --dll-verbose
1732 --verbose[=NUMBER]
1733 Display the version number for ld and list the linker emulations
1734 supported. Display which input files can and cannot be opened.
1735 Display the linker script being used by the linker. If the optional
1736 NUMBER argument > 1, plugin symbol status will also be displayed.
1737 --version-script=version-scriptfile
1739 Specify the name of a version script to the linker. This is
1740 typically used when creating shared libraries to specify additional
1741 information about the version hierarchy for the library being
1742 created. This option is only fully supported on ELF platforms
1743 which support shared libraries; see VERSION. It is partially
1744 supported on PE platforms, which can use version scripts to filter
1745 symbol visibility in auto-export mode: any symbols marked local in
1746 the version script will not be exported.
1747 --warn-common
1749 Warn when a common symbol is combined with another common symbol or
1750 with a symbol definition. Unix linkers allow this somewhat sloppy
1751 practice, but linkers on some other operating systems do not. This
1752 option allows you to find potential problems from combining global
1753 symbols. Unfortunately, some C libraries use this practice, so you
1754 may get some warnings about symbols in the libraries as well as in
1755 your programs.
1756 There are three kinds of global symbols, illustrated here by C
1758 examples:
1759 int i = 1;
1761 A definition, which goes in the initialized data section of the
1762 output file.
1763 extern int i;
1765 An undefined reference, which does not allocate space. There
1766 must be either a definition or a common symbol for the variable
1767 somewhere.
1768 int i;
1770 A common symbol. If there are only (one or more) common
1771 symbols for a variable, it goes in the uninitialized data area
1772 of the output file. The linker merges multiple common symbols
1773 for the same variable into a single symbol. If they are of
1774 different sizes, it picks the largest size. The linker turns a
1775 common symbol into a declaration, if there is a definition of
1776 the same variable.
1777 The --warn-common option can produce five kinds of warnings. Each
1779 warning consists of a pair of lines: the first describes the symbol
1780 just encountered, and the second describes the previous symbol
1781 encountered with the same name. One or both of the two symbols
1782 will be a common symbol.
1783 1. Turning a common symbol into a reference, because there is
1785 already a definition for the symbol.
1786 <file>(<section>): warning: common of `<symbol>'
1788 overridden by definition
1789 <file>(<section>): warning: defined here
1790 2. Turning a common symbol into a reference, because a later
1792 definition for the symbol is encountered. This is the same as
1793 the previous case, except that the symbols are encountered in a
1794 different order.
1795 <file>(<section>): warning: definition of `<symbol>'
1797 overriding common
1798 <file>(<section>): warning: common is here
1799 3. Merging a common symbol with a previous same-sized common
1801 symbol.
1802 <file>(<section>): warning: multiple common
1804 of `<symbol>'
1805 <file>(<section>): warning: previous common is here
1806 4. Merging a common symbol with a previous larger common symbol.
1808 <file>(<section>): warning: common of `<symbol>'
1810 overridden by larger common
1811 <file>(<section>): warning: larger common is here
1812 5. Merging a common symbol with a previous smaller common symbol.
1814 This is the same as the previous case, except that the symbols
1815 are encountered in a different order.
1816 <file>(<section>): warning: common of `<symbol>'
1818 overriding smaller common
1819 <file>(<section>): warning: smaller common is here
1820 --warn-constructors
1822 Warn if any global constructors are used. This is only useful for
1823 a few object file formats. For formats like COFF or ELF, the
1824 linker can not detect the use of global constructors.
1825 --warn-multiple-gp
1827 Warn if multiple global pointer values are required in the output
1828 file. This is only meaningful for certain processors, such as the
1829 Alpha. Specifically, some processors put large-valued constants in
1830 a special section. A special register (the global pointer) points
1831 into the middle of this section, so that constants can be loaded
1832 efficiently via a base-register relative addressing mode. Since
1833 the offset in base-register relative mode is fixed and relatively
1834 small (e.g., 16 bits), this limits the maximum size of the constant
1835 pool. Thus, in large programs, it is often necessary to use
1836 multiple global pointer values in order to be able to address all
1837 possible constants. This option causes a warning to be issued
1838 whenever this case occurs.
1839 --warn-once
1841 Only warn once for each undefined symbol, rather than once per
1842 module which refers to it.
1843 --warn-section-align
1845 Warn if the address of an output section is changed because of
1846 alignment. Typically, the alignment will be set by an input
1847 section. The address will only be changed if it not explicitly
1848 specified; that is, if the "SECTIONS" command does not specify a
1849 start address for the section.
1850 --warn-textrel
1852 Warn if the linker adds DT_TEXTREL to a position-independent
1853 executable or shared object.
1854 --warn-alternate-em
1856 Warn if an object has alternate ELF machine code.
1857 --warn-unresolved-symbols
1859 If the linker is going to report an unresolved symbol (see the
1860 option --unresolved-symbols) it will normally generate an error.
1861 This option makes it generate a warning instead.
1862 --error-unresolved-symbols
1864 This restores the linker's default behaviour of generating errors
1865 when it is reporting unresolved symbols.
1866 --whole-archive
1868 For each archive mentioned on the command line after the
1869 --whole-archive option, include every object file in the archive in
1870 the link, rather than searching the archive for the required object
1871 files. This is normally used to turn an archive file into a shared
1872 library, forcing every object to be included in the resulting
1873 shared library. This option may be used more than once.
1874 Two notes when using this option from gcc: First, gcc doesn't know
1876 about this option, so you have to use -Wl,-whole-archive. Second,
1877 don't forget to use -Wl,-no-whole-archive after your list of
1878 archives, because gcc will add its own list of archives to your
1879 link and you may not want this flag to affect those as well.
1880 --wrap=symbol
1882 Use a wrapper function for symbol. Any undefined reference to
1883 symbol will be resolved to "__wrap_symbol". Any undefined
1884 reference to "__real_symbol" will be resolved to symbol.
1885 This can be used to provide a wrapper for a system function. The
1887 wrapper function should be called "__wrap_symbol". If it wishes to
1888 call the system function, it should call "__real_symbol".
1889 Here is a trivial example:
1891 void *
1893 __wrap_malloc (size_t c)
1894 {
1895 printf ("malloc called with %zu\n", c);
1896 return __real_malloc (c);
1897 }
1898 If you link other code with this file using --wrap malloc, then all
1900 calls to "malloc" will call the function "__wrap_malloc" instead.
1901 The call to "__real_malloc" in "__wrap_malloc" will call the real
1902 "malloc" function.
1903 You may wish to provide a "__real_malloc" function as well, so that
1905 links without the --wrap option will succeed. If you do this, you
1906 should not put the definition of "__real_malloc" in the same file
1907 as "__wrap_malloc"; if you do, the assembler may resolve the call
1908 before the linker has a chance to wrap it to "malloc".
1909 Only undefined references are replaced by the linker. So,
1911 translation unit internal references to symbol are not resolved to
1912 "__wrap_symbol". In the next example, the call to "f" in "g" is
1913 not resolved to "__wrap_f".
1914 int
1916 f (void)
1917 {
1918 return 123;
1919 }
1920 int
1922 g (void)
1923 {
1924 return f();
1925 }
1926 --eh-frame-hdr
1928 --no-eh-frame-hdr
1929 Request (--eh-frame-hdr) or suppress (--no-eh-frame-hdr) the
1930 creation of ".eh_frame_hdr" section and ELF "PT_GNU_EH_FRAME"
1931 segment header.
1932 --no-ld-generated-unwind-info
1934 Request creation of ".eh_frame" unwind info for linker generated
1935 code sections like PLT. This option is on by default if linker
1936 generated unwind info is supported.
1937 --enable-new-dtags
1939 --disable-new-dtags
1940 This linker can create the new dynamic tags in ELF. But the older
1941 ELF systems may not understand them. If you specify
1942 --enable-new-dtags, the new dynamic tags will be created as needed
1943 and older dynamic tags will be omitted. If you specify
1944 --disable-new-dtags, no new dynamic tags will be created. By
1945 default, the new dynamic tags are not created. Note that those
1946 options are only available for ELF systems.
1947 --hash-size=number
1949 Set the default size of the linker's hash tables to a prime number
1950 close to number. Increasing this value can reduce the length of
1951 time it takes the linker to perform its tasks, at the expense of
1952 increasing the linker's memory requirements. Similarly reducing
1953 this value can reduce the memory requirements at the expense of
1954 speed.
1955 --hash-style=style
1957 Set the type of linker's hash table(s). style can be either "sysv"
1958 for classic ELF ".hash" section, "gnu" for new style GNU
1959 ".gnu.hash" section or "both" for both the classic ELF ".hash" and
1960 new style GNU ".gnu.hash" hash tables. The default depends upon
1961 how the linker was configured, but for most Linux based systems it
1962 will be "both".
1963 --compress-debug-sections=none
1965 --compress-debug-sections=zlib
1966 --compress-debug-sections=zlib-gnu
1967 --compress-debug-sections=zlib-gabi
1968 On ELF platforms, these options control how DWARF debug sections
1969 are compressed using zlib.
1970 --compress-debug-sections=none doesn't compress DWARF debug
1972 sections. --compress-debug-sections=zlib-gnu compresses DWARF
1973 debug sections and renames them to begin with .zdebug instead of
1974 .debug. --compress-debug-sections=zlib-gabi also compresses DWARF
1975 debug sections, but rather than renaming them it sets the
1976 SHF_COMPRESSED flag in the sections' headers.
1977 The --compress-debug-sections=zlib option is an alias for
1979 --compress-debug-sections=zlib-gabi.
1980 Note that this option overrides any compression in input debug
1982 sections, so if a binary is linked with
1983 --compress-debug-sections=none for example, then any compressed
1984 debug sections in input files will be uncompressed before they are
1985 copied into the output binary.
1986 The default compression behaviour varies depending upon the target
1988 involved and the configure options used to build the toolchain.
1989 The default can be determined by examining the output from the
1990 linker's --help option.
1991 --reduce-memory-overheads
1993 This option reduces memory requirements at ld runtime, at the
1994 expense of linking speed. This was introduced to select the old
1995 O(n^2) algorithm for link map file generation, rather than the new
1996 O(n) algorithm which uses about 40% more memory for symbol storage.
1997 Another effect of the switch is to set the default hash table size
1999 to 1021, which again saves memory at the cost of lengthening the
2000 linker's run time. This is not done however if the --hash-size
2001 switch has been used.
2002 The --reduce-memory-overheads switch may be also be used to enable
2004 other tradeoffs in future versions of the linker.
2005 --build-id
2007 --build-id=style
2008 Request the creation of a ".note.gnu.build-id" ELF note section or
2009 a ".buildid" COFF section. The contents of the note are unique
2010 bits identifying this linked file. style can be "uuid" to use 128
2011 random bits, "sha1" to use a 160-bit SHA1 hash on the normative
2012 parts of the output contents, "md5" to use a 128-bit MD5 hash on
2013 the normative parts of the output contents, or "0xhexstring" to use
2014 a chosen bit string specified as an even number of hexadecimal
2015 digits ("-" and ":" characters between digit pairs are ignored).
2016 If style is omitted, "sha1" is used.
2017 The "md5" and "sha1" styles produces an identifier that is always
2019 the same in an identical output file, but will be unique among all
2020 nonidentical output files. It is not intended to be compared as a
2021 checksum for the file's contents. A linked file may be changed
2022 later by other tools, but the build ID bit string identifying the
2023 original linked file does not change.
2024 Passing "none" for style disables the setting from any "--build-id"
2026 options earlier on the command line.
2027 The i386 PE linker supports the -shared option, which causes the output
2029 to be a dynamically linked library (DLL) instead of a normal
2030 executable. You should name the output "*.dll" when you use this
2031 option. In addition, the linker fully supports the standard "*.def"
2032 files, which may be specified on the linker command line like an object
2033 file (in fact, it should precede archives it exports symbols from, to
2034 ensure that they get linked in, just like a normal object file).
2035 In addition to the options common to all targets, the i386 PE linker
2037 support additional command-line options that are specific to the i386
2038 PE target. Options that take values may be separated from their values
2039 by either a space or an equals sign.
2040 --add-stdcall-alias
2042 If given, symbols with a stdcall suffix (@nn) will be exported as-
2043 is and also with the suffix stripped. [This option is specific to
2044 the i386 PE targeted port of the linker]
2045 --base-file file
2047 Use file as the name of a file in which to save the base addresses
2048 of all the relocations needed for generating DLLs with dlltool.
2049 [This is an i386 PE specific option]
2050 --dll
2052 Create a DLL instead of a regular executable. You may also use
2053 -shared or specify a "LIBRARY" in a given ".def" file. [This
2054 option is specific to the i386 PE targeted port of the linker]
2055 --enable-long-section-names
2057 --disable-long-section-names
2058 The PE variants of the COFF object format add an extension that
2059 permits the use of section names longer than eight characters, the
2060 normal limit for COFF. By default, these names are only allowed in
2061 object files, as fully-linked executable images do not carry the
2062 COFF string table required to support the longer names. As a GNU
2063 extension, it is possible to allow their use in executable images
2064 as well, or to (probably pointlessly!) disallow it in object
2065 files, by using these two options. Executable images generated
2066 with these long section names are slightly non-standard, carrying
2067 as they do a string table, and may generate confusing output when
2068 examined with non-GNU PE-aware tools, such as file viewers and
2069 dumpers. However, GDB relies on the use of PE long section names
2070 to find Dwarf-2 debug information sections in an executable image
2071 at runtime, and so if neither option is specified on the command-
2072 line, ld will enable long section names, overriding the default and
2073 technically correct behaviour, when it finds the presence of debug
2074 information while linking an executable image and not stripping
2075 symbols. [This option is valid for all PE targeted ports of the
2076 linker]
2077 --enable-stdcall-fixup
2079 --disable-stdcall-fixup
2080 If the link finds a symbol that it cannot resolve, it will attempt
2081 to do "fuzzy linking" by looking for another defined symbol that
2082 differs only in the format of the symbol name (cdecl vs stdcall)
2083 and will resolve that symbol by linking to the match. For example,
2084 the undefined symbol "_foo" might be linked to the function
2085 "_foo@12", or the undefined symbol "_bar@16" might be linked to the
2086 function "_bar". When the linker does this, it prints a warning,
2087 since it normally should have failed to link, but sometimes import
2088 libraries generated from third-party dlls may need this feature to
2089 be usable. If you specify --enable-stdcall-fixup, this feature is
2090 fully enabled and warnings are not printed. If you specify
2091 --disable-stdcall-fixup, this feature is disabled and such
2092 mismatches are considered to be errors. [This option is specific
2093 to the i386 PE targeted port of the linker]
2094 --leading-underscore
2096 --no-leading-underscore
2097 For most targets default symbol-prefix is an underscore and is
2098 defined in target's description. By this option it is possible to
2099 disable/enable the default underscore symbol-prefix.
2100 --export-all-symbols
2102 If given, all global symbols in the objects used to build a DLL
2103 will be exported by the DLL. Note that this is the default if
2104 there otherwise wouldn't be any exported symbols. When symbols are
2105 explicitly exported via DEF files or implicitly exported via
2106 function attributes, the default is to not export anything else
2107 unless this option is given. Note that the symbols "DllMain@12",
2108 "DllEntryPoint@0", "DllMainCRTStartup@12", and "impure_ptr" will
2109 not be automatically exported. Also, symbols imported from other
2110 DLLs will not be re-exported, nor will symbols specifying the DLL's
2111 internal layout such as those beginning with "_head_" or ending
2112 with "_iname". In addition, no symbols from "libgcc", "libstd++",
2113 "libmingw32", or "crtX.o" will be exported. Symbols whose names
2114 begin with "__rtti_" or "__builtin_" will not be exported, to help
2115 with C++ DLLs. Finally, there is an extensive list of cygwin-
2116 private symbols that are not exported (obviously, this applies on
2117 when building DLLs for cygwin targets). These cygwin-excludes are:
2118 "_cygwin_dll_entry@12", "_cygwin_crt0_common@8",
2119 "_cygwin_noncygwin_dll_entry@12", "_fmode", "_impure_ptr",
2120 "cygwin_attach_dll", "cygwin_premain0", "cygwin_premain1",
2121 "cygwin_premain2", "cygwin_premain3", and "environ". [This option
2122 is specific to the i386 PE targeted port of the linker]
2123 --exclude-symbols symbol,symbol,...
2125 Specifies a list of symbols which should not be automatically
2126 exported. The symbol names may be delimited by commas or colons.
2127 [This option is specific to the i386 PE targeted port of the
2128 linker]
2129 --exclude-all-symbols
2131 Specifies no symbols should be automatically exported. [This
2132 option is specific to the i386 PE targeted port of the linker]
2133 --file-alignment
2135 Specify the file alignment. Sections in the file will always begin
2136 at file offsets which are multiples of this number. This defaults
2137 to 512. [This option is specific to the i386 PE targeted port of
2138 the linker]
2139 --heap reserve
2141 --heap reserve,commit
2142 Specify the number of bytes of memory to reserve (and optionally
2143 commit) to be used as heap for this program. The default is 1MB
2144 reserved, 4K committed. [This option is specific to the i386 PE
2145 targeted port of the linker]
2146 --image-base value
2148 Use value as the base address of your program or dll. This is the
2149 lowest memory location that will be used when your program or dll
2150 is loaded. To reduce the need to relocate and improve performance
2151 of your dlls, each should have a unique base address and not
2152 overlap any other dlls. The default is 0x400000 for executables,
2153 and 0x10000000 for dlls. [This option is specific to the i386 PE
2154 targeted port of the linker]
2155 --kill-at
2157 If given, the stdcall suffixes (@nn) will be stripped from symbols
2158 before they are exported. [This option is specific to the i386 PE
2159 targeted port of the linker]
2160 --large-address-aware
2162 If given, the appropriate bit in the "Characteristics" field of the
2163 COFF header is set to indicate that this executable supports
2164 virtual addresses greater than 2 gigabytes. This should be used in
2165 conjunction with the /3GB or /USERVA=value megabytes switch in the
2166 "[operating systems]" section of the BOOT.INI. Otherwise, this bit
2167 has no effect. [This option is specific to PE targeted ports of
2168 the linker]
2169 --disable-large-address-aware
2171 Reverts the effect of a previous --large-address-aware option.
2172 This is useful if --large-address-aware is always set by the
2173 compiler driver (e.g. Cygwin gcc) and the executable does not
2174 support virtual addresses greater than 2 gigabytes. [This option
2175 is specific to PE targeted ports of the linker]
2176 --major-image-version value
2178 Sets the major number of the "image version". Defaults to 1.
2179 [This option is specific to the i386 PE targeted port of the
2180 linker]
2181 --major-os-version value
2183 Sets the major number of the "os version". Defaults to 4. [This
2184 option is specific to the i386 PE targeted port of the linker]
2185 --major-subsystem-version value
2187 Sets the major number of the "subsystem version". Defaults to 4.
2188 [This option is specific to the i386 PE targeted port of the
2189 linker]
2190 --minor-image-version value
2192 Sets the minor number of the "image version". Defaults to 0.
2193 [This option is specific to the i386 PE targeted port of the
2194 linker]
2195 --minor-os-version value
2197 Sets the minor number of the "os version". Defaults to 0. [This
2198 option is specific to the i386 PE targeted port of the linker]
2199 --minor-subsystem-version value
2201 Sets the minor number of the "subsystem version". Defaults to 0.
2202 [This option is specific to the i386 PE targeted port of the
2203 linker]
2204 --output-def file
2206 The linker will create the file file which will contain a DEF file
2207 corresponding to the DLL the linker is generating. This DEF file
2208 (which should be called "*.def") may be used to create an import
2209 library with "dlltool" or may be used as a reference to
2210 automatically or implicitly exported symbols. [This option is
2211 specific to the i386 PE targeted port of the linker]
2212 --enable-auto-image-base
2214 --enable-auto-image-base=value
2215 Automatically choose the image base for DLLs, optionally starting
2216 with base value, unless one is specified using the "--image-base"
2217 argument. By using a hash generated from the dllname to create
2218 unique image bases for each DLL, in-memory collisions and
2219 relocations which can delay program execution are avoided. [This
2220 option is specific to the i386 PE targeted port of the linker]
2221 --disable-auto-image-base
2223 Do not automatically generate a unique image base. If there is no
2224 user-specified image base ("--image-base") then use the platform
2225 default. [This option is specific to the i386 PE targeted port of
2226 the linker]
2227 --dll-search-prefix string
2229 When linking dynamically to a dll without an import library, search
2230 for "<string><basename>.dll" in preference to "lib<basename>.dll".
2231 This behaviour allows easy distinction between DLLs built for the
2232 various "subplatforms": native, cygwin, uwin, pw, etc. For
2233 instance, cygwin DLLs typically use "--dll-search-prefix=cyg".
2234 [This option is specific to the i386 PE targeted port of the
2235 linker]
2236 --enable-auto-import
2238 Do sophisticated linking of "_symbol" to "__imp__symbol" for DATA
2239 imports from DLLs, thus making it possible to bypass the dllimport
2240 mechanism on the user side and to reference unmangled symbol names.
2241 [This option is specific to the i386 PE targeted port of the
2242 linker]
2243 The following remarks pertain to the original implementation of the
2245 feature and are obsolete nowadays for Cygwin and MinGW targets.
2246 Note: Use of the 'auto-import' extension will cause the text
2248 section of the image file to be made writable. This does not
2249 conform to the PE-COFF format specification published by Microsoft.
2250 Note - use of the 'auto-import' extension will also cause read only
2252 data which would normally be placed into the .rdata section to be
2253 placed into the .data section instead. This is in order to work
2254 around a problem with consts that is described here:
2255 http://www.cygwin.com/ml/cygwin/2004-09/msg01101.html
2256 Using 'auto-import' generally will 'just work' -- but sometimes you
2258 may see this message:
2259 "variable '<var>' can't be auto-imported. Please read the
2261 documentation for ld's "--enable-auto-import" for details."
2262 This message occurs when some (sub)expression accesses an address
2264 ultimately given by the sum of two constants (Win32 import tables
2265 only allow one). Instances where this may occur include accesses
2266 to member fields of struct variables imported from a DLL, as well
2267 as using a constant index into an array variable imported from a
2268 DLL. Any multiword variable (arrays, structs, long long, etc) may
2269 trigger this error condition. However, regardless of the exact
2270 data type of the offending exported variable, ld will always detect
2271 it, issue the warning, and exit.
2272 There are several ways to address this difficulty, regardless of
2274 the data type of the exported variable:
2275 One way is to use --enable-runtime-pseudo-reloc switch. This leaves
2277 the task of adjusting references in your client code for runtime
2278 environment, so this method works only when runtime environment
2279 supports this feature.
2280 A second solution is to force one of the 'constants' to be a
2282 variable -- that is, unknown and un-optimizable at compile time.
2283 For arrays, there are two possibilities: a) make the indexee (the
2284 array's address) a variable, or b) make the 'constant' index a
2285 variable. Thus:
2286 extern type extern_array[];
2288 extern_array[1] -->
2289 { volatile type *t=extern_array; t[1] }
2290 or
2292 extern type extern_array[];
2294 extern_array[1] -->
2295 { volatile int t=1; extern_array[t] }
2296 For structs (and most other multiword data types) the only option
2298 is to make the struct itself (or the long long, or the ...)
2299 variable:
2300 extern struct s extern_struct;
2302 extern_struct.field -->
2303 { volatile struct s *t=&extern_struct; t->field }
2304 or
2306 extern long long extern_ll;
2308 extern_ll -->
2309 { volatile long long * local_ll=&extern_ll; *local_ll }
2310 A third method of dealing with this difficulty is to abandon
2312 'auto-import' for the offending symbol and mark it with
2313 "__declspec(dllimport)". However, in practice that requires using
2314 compile-time #defines to indicate whether you are building a DLL,
2315 building client code that will link to the DLL, or merely
2316 building/linking to a static library. In making the choice
2317 between the various methods of resolving the 'direct address with
2318 constant offset' problem, you should consider typical real-world
2319 usage:
2320 Original:
2322 --foo.h
2324 extern int arr[];
2325 --foo.c
2326 #include "foo.h"
2327 void main(int argc, char **argv){
2328 printf("%d\n",arr[1]);
2329 }
2330 Solution 1:
2332 --foo.h
2334 extern int arr[];
2335 --foo.c
2336 #include "foo.h"
2337 void main(int argc, char **argv){
2338 /* This workaround is for win32 and cygwin; do not "optimize" */
2339 volatile int *parr = arr;
2340 printf("%d\n",parr[1]);
2341 }
2342 Solution 2:
2344 --foo.h
2346 /* Note: auto-export is assumed (no __declspec(dllexport)) */
2347 #if (defined(_WIN32) || defined(__CYGWIN__)) && \
2348 !(defined(FOO_BUILD_DLL) || defined(FOO_STATIC))
2349 #define FOO_IMPORT __declspec(dllimport)
2350 #else
2351 #define FOO_IMPORT
2352 #endif
2353 extern FOO_IMPORT int arr[];
2354 --foo.c
2355 #include "foo.h"
2356 void main(int argc, char **argv){
2357 printf("%d\n",arr[1]);
2358 }
2359 A fourth way to avoid this problem is to re-code your library to
2361 use a functional interface rather than a data interface for the
2362 offending variables (e.g. set_foo() and get_foo() accessor
2363 functions).
2364 --disable-auto-import
2366 Do not attempt to do sophisticated linking of "_symbol" to
2367 "__imp__symbol" for DATA imports from DLLs. [This option is
2368 specific to the i386 PE targeted port of the linker]
2369 --enable-runtime-pseudo-reloc
2371 If your code contains expressions described in --enable-auto-import
2372 section, that is, DATA imports from DLL with non-zero offset, this
2373 switch will create a vector of 'runtime pseudo relocations' which
2374 can be used by runtime environment to adjust references to such
2375 data in your client code. [This option is specific to the i386 PE
2376 targeted port of the linker]
2377 --disable-runtime-pseudo-reloc
2379 Do not create pseudo relocations for non-zero offset DATA imports
2380 from DLLs. [This option is specific to the i386 PE targeted port
2381 of the linker]
2382 --enable-extra-pe-debug
2384 Show additional debug info related to auto-import symbol thunking.
2385 [This option is specific to the i386 PE targeted port of the
2386 linker]
2387 --section-alignment
2389 Sets the section alignment. Sections in memory will always begin
2390 at addresses which are a multiple of this number. Defaults to
2391 0x1000. [This option is specific to the i386 PE targeted port of
2392 the linker]
2393 --stack reserve
2395 --stack reserve,commit
2396 Specify the number of bytes of memory to reserve (and optionally
2397 commit) to be used as stack for this program. The default is 2MB
2398 reserved, 4K committed. [This option is specific to the i386 PE
2399 targeted port of the linker]
2400 --subsystem which
2402 --subsystem which:major
2403 --subsystem which:major.minor
2404 Specifies the subsystem under which your program will execute. The
2405 legal values for which are "native", "windows", "console", "posix",
2406 and "xbox". You may optionally set the subsystem version also.
2407 Numeric values are also accepted for which. [This option is
2408 specific to the i386 PE targeted port of the linker]
2409 The following options set flags in the "DllCharacteristics" field
2411 of the PE file header: [These options are specific to PE targeted
2412 ports of the linker]
2413 --high-entropy-va
2415 Image is compatible with 64-bit address space layout randomization
2416 (ASLR). This option also implies --dynamicbase and
2417 --enable-reloc-section.
2418 --dynamicbase
2420 The image base address may be relocated using address space layout
2421 randomization (ASLR). This feature was introduced with MS Windows
2422 Vista for i386 PE targets. This option also implies
2423 --enable-reloc-section.
2424 --forceinteg
2426 Code integrity checks are enforced.
2427 --nxcompat
2429 The image is compatible with the Data Execution Prevention. This
2430 feature was introduced with MS Windows XP SP2 for i386 PE targets.
2431 --no-isolation
2433 Although the image understands isolation, do not isolate the image.
2434 --no-seh
2436 The image does not use SEH. No SE handler may be called from this
2437 image.
2438 --no-bind
2440 Do not bind this image.
2441 --wdmdriver
2443 The driver uses the MS Windows Driver Model.
2444 --tsaware
2446 The image is Terminal Server aware.
2447 --insert-timestamp
2449 --no-insert-timestamp
2450 Insert a real timestamp into the image. This is the default
2451 behaviour as it matches legacy code and it means that the image
2452 will work with other, proprietary tools. The problem with this
2453 default is that it will result in slightly different images being
2454 produced each time the same sources are linked. The option
2455 --no-insert-timestamp can be used to insert a zero value for the
2456 timestamp, this ensuring that binaries produced from identical
2457 sources will compare identically.
2458 --enable-reloc-section
2460 Create the base relocation table, which is necessary if the image
2461 is loaded at a different image base than specified in the PE
2462 header.
2463 The C6X uClinux target uses a binary format called DSBT to support
2465 shared libraries. Each shared library in the system needs to have a
2466 unique index; all executables use an index of 0.
2467 --dsbt-size size
2469 This option sets the number of entries in the DSBT of the current
2470 executable or shared library to size. The default is to create a
2471 table with 64 entries.
2472 --dsbt-index index
2474 This option sets the DSBT index of the current executable or shared
2475 library to index. The default is 0, which is appropriate for
2476 generating executables. If a shared library is generated with a
2477 DSBT index of 0, the "R_C6000_DSBT_INDEX" relocs are copied into
2478 the output file.
2479 The --no-merge-exidx-entries switch disables the merging of
2481 adjacent exidx entries in frame unwind info.
2482 --branch-stub
2484 This option enables linker branch relaxation by inserting branch
2485 stub sections when needed to extend the range of branches. This
2486 option is usually not required since C-SKY supports branch and call
2487 instructions that can access the full memory range and branch
2488 relaxation is normally handled by the compiler or assembler.
2489 --stub-group-size=N
2491 This option allows finer control of linker branch stub creation.
2492 It sets the maximum size of a group of input sections that can be
2493 handled by one stub section. A negative value of N locates stub
2494 sections after their branches, while a positive value allows stub
2495 sections to appear either before or after the branches. Values of
2496 1 or -1 indicate that the linker should choose suitable defaults.
2497 The 68HC11 and 68HC12 linkers support specific options to control the
2499 memory bank switching mapping and trampoline code generation.
2500 --no-trampoline
2502 This option disables the generation of trampoline. By default a
2503 trampoline is generated for each far function which is called using
2504 a "jsr" instruction (this happens when a pointer to a far function
2505 is taken).
2506 --bank-window name
2508 This option indicates to the linker the name of the memory region
2509 in the MEMORY specification that describes the memory bank window.
2510 The definition of such region is then used by the linker to compute
2511 paging and addresses within the memory window.
2512 The following options are supported to control handling of GOT
2514 generation when linking for 68K targets.
2515 --got=type
2517 This option tells the linker which GOT generation scheme to use.
2518 type should be one of single, negative, multigot or target. For
2519 more information refer to the Info entry for ld.
2520 The following options are supported to control microMIPS instruction
2522 generation and branch relocation checks for ISA mode transitions when
2523 linking for MIPS targets.
2524 --insn32
2526 --no-insn32
2527 These options control the choice of microMIPS instructions used in
2528 code generated by the linker, such as that in the PLT or lazy
2529 binding stubs, or in relaxation. If --insn32 is used, then the
2530 linker only uses 32-bit instruction encodings. By default or if
2531 --no-insn32 is used, all instruction encodings are used, including
2532 16-bit ones where possible.
2533 --ignore-branch-isa
2535 --no-ignore-branch-isa
2536 These options control branch relocation checks for invalid ISA mode
2537 transitions. If --ignore-branch-isa is used, then the linker
2538 accepts any branch relocations and any ISA mode transition required
2539 is lost in relocation calculation, except for some cases of "BAL"
2540 instructions which meet relaxation conditions and are converted to
2541 equivalent "JALX" instructions as the associated relocation is
2542 calculated. By default or if --no-ignore-branch-isa is used a
2543 check is made causing the loss of an ISA mode transition to produce
2544 an error.
2545 --compact-branches
2547 --no-compact-branches
2548 These options control the generation of compact instructions by the
2549 linker in the PLT entries for MIPS R6.
2550 For the pdp11-aout target, three variants of the output format can be
2552 produced as selected by the following options. The default variant for
2553 pdp11-aout is the --omagic option, whereas for other targets --nmagic
2554 is the default. The --imagic option is defined only for the pdp11-aout
2555 target, while the others are described here as they apply to the
2556 pdp11-aout target.
2557 -N
2559 --omagic
2560 Mark the output as "OMAGIC" (0407) in the a.out header to indicate
2561 that the text segment is not to be write-protected and shared.
2562 Since the text and data sections are both readable and writable,
2563 the data section is allocated immediately contiguous after the text
2564 segment. This is the oldest format for PDP11 executable programs
2565 and is the default for ld on PDP11 Unix systems from the beginning
2566 through 2.11BSD.
2567 -n
2569 --nmagic
2570 Mark the output as "NMAGIC" (0410) in the a.out header to indicate
2571 that when the output file is executed, the text portion will be
2572 read-only and shareable among all processes executing the same
2573 file. This involves moving the data areas up to the first possible
2574 8K byte page boundary following the end of the text. This option
2575 creates a pure executable format.
2576 -z
2578 --imagic
2579 Mark the output as "IMAGIC" (0411) in the a.out header to indicate
2580 that when the output file is executed, the program text and data
2581 areas will be loaded into separate address spaces using the split
2582 instruction and data space feature of the memory management unit in
2583 larger models of the PDP11. This doubles the address space
2584 available to the program. The text segment is again pure, write-
2585 protected, and shareable. The only difference in the output format
2586 between this option and the others, besides the magic number, is
2587 that both the text and data sections start at location 0. The -z
2588 option selected this format in 2.11BSD. This option creates a
2589 separate executable format.
2590 --no-omagic
2592 Equivalent to --nmagic for pdp11-aout.
2593
2595 You can change the behaviour of ld with the environment variables
2596 "GNUTARGET", "LDEMULATION" and "COLLECT_NO_DEMANGLE".
2597 "GNUTARGET" determines the input-file object format if you don't use -b
2599 (or its synonym --format). Its value should be one of the BFD names
2600 for an input format. If there is no "GNUTARGET" in the environment, ld
2601 uses the natural format of the target. If "GNUTARGET" is set to
2602 "default" then BFD attempts to discover the input format by examining
2603 binary input files; this method often succeeds, but there are potential
2604 ambiguities, since there is no method of ensuring that the magic number
2605 used to specify object-file formats is unique. However, the
2606 configuration procedure for BFD on each system places the conventional
2607 format for that system first in the search-list, so ambiguities are
2608 resolved in favor of convention.
2609 "LDEMULATION" determines the default emulation if you don't use the -m
2611 option. The emulation can affect various aspects of linker behaviour,
2612 particularly the default linker script. You can list the available
2613 emulations with the --verbose or -V options. If the -m option is not
2614 used, and the "LDEMULATION" environment variable is not defined, the
2615 default emulation depends upon how the linker was configured.
2616 Normally, the linker will default to demangling symbols. However, if
2618 "COLLECT_NO_DEMANGLE" is set in the environment, then it will default
2619 to not demangling symbols. This environment variable is used in a
2620 similar fashion by the "gcc" linker wrapper program. The default may
2621 be overridden by the --demangle and --no-demangle options.
2622
2624 ar(1), nm(1), objcopy(1), objdump(1), readelf(1) and the Info entries
2625 for binutils and ld.
2626
2628 Copyright (c) 1991-2020 Free Software Foundation, Inc.
2629 Permission is granted to copy, distribute and/or modify this document
2631 under the terms of the GNU Free Documentation License, Version 1.3 or
2632 any later version published by the Free Software Foundation; with no
2633 Invariant Sections, with no Front-Cover Texts, and with no Back-Cover
2634 Texts. A copy of the license is included in the section entitled "GNU
2635 Free Documentation License".
2636binutils-2.35 2020-07-24 LD(1)