1LD(1)                        GNU Development Tools                       LD(1)
2
3
4

NAME

6       ld - The GNU linker
7

SYNOPSIS

9       ld [options] objfile ...
10

DESCRIPTION

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
16       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
20       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
24       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
30       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
36       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

OPTIONS

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
47               ld -o <output> /lib/crt0.o hello.o -lc
48
49       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
54       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
64       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
69       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
75       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
86       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
91       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
99       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
105       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
110                 gcc -Wl,--start-group foo.o bar.o -Wl,--end-group
111
112       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
120                 gcc foo.o bar.o -Wl,-eENTRY -Wl,-Map=a.map
121
122       Here is a table of the generic command line switches accepted by the
123       GNU linker:
124
125       @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
131           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
138       -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
145       --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
155       -A architecture
156       --architecture=architecture
157           In the current release of ld, this option is useful only for the
158           Intel 960 family of architectures.  In that ld configuration, the
159           architecture argument identifies the particular architecture in the
160           960 family, enabling some safeguards and modifying the archive-
161           library search path.
162
163           Future releases of ld may support similar functionality for other
164           architecture families.
165
166       -b input-format
167       --format=input-format
168           ld may be configured to support more than one kind of object file.
169           If your ld is configured this way, you can use the -b option to
170           specify the binary format for input object files that follow this
171           option on the command line.  Even when ld is configured to support
172           alternative object formats, you don't usually need to specify this,
173           as ld should be configured to expect as a default input format the
174           most usual format on each machine.  input-format is a text string,
175           the name of a particular format supported by the BFD libraries.
176           (You can list the available binary formats with objdump -i.)
177
178           You may want to use this option if you are linking files with an
179           unusual binary format.  You can also use -b to switch formats
180           explicitly (when linking object files of different formats), by
181           including -b input-format before each group of object files in a
182           particular format.
183
184           The default format is taken from the environment variable
185           "GNUTARGET".
186
187           You can also define the input format from a script, using the
188           command "TARGET";
189
190       -c MRI-commandfile
191       --mri-script=MRI-commandfile
192           For compatibility with linkers produced by MRI, ld accepts script
193           files written in an alternate, restricted command language,
194           described in the MRI Compatible Script Files section of GNU ld
195           documentation.  Introduce MRI script files with the option -c; use
196           the -T option to run linker scripts written in the general-purpose
197           ld scripting language.  If MRI-cmdfile does not exist, ld looks for
198           it in the directories specified by any -L options.
199
200       -d
201       -dc
202       -dp These three options are equivalent; multiple forms are supported
203           for compatibility with other linkers.  They assign space to common
204           symbols even if a relocatable output file is specified (with -r).
205           The script command "FORCE_COMMON_ALLOCATION" has the same effect.
206
207       --depaudit AUDITLIB
208       -P AUDITLIB
209           Adds AUDITLIB to the "DT_DEPAUDIT" entry of the dynamic section.
210           AUDITLIB is not checked for existence, nor will it use the
211           DT_SONAME specified in the library.  If specified multiple times
212           "DT_DEPAUDIT" will contain a colon separated list of audit
213           interfaces to use.  This option is only meaningful on ELF platforms
214           supporting the rtld-audit interface.  The -P option is provided for
215           Solaris compatibility.
216
217       -e entry
218       --entry=entry
219           Use entry as the explicit symbol for beginning execution of your
220           program, rather than the default entry point.  If there is no
221           symbol named entry, the linker will try to parse entry as a number,
222           and use that as the entry address (the number will be interpreted
223           in base 10; you may use a leading 0x for base 16, or a leading 0
224           for base 8).
225
226       --exclude-libs lib,lib,...
227           Specifies a list of archive libraries from which symbols should not
228           be automatically exported.  The library names may be delimited by
229           commas or colons.  Specifying "--exclude-libs ALL" excludes symbols
230           in all archive libraries from automatic export.  This option is
231           available only for the i386 PE targeted port of the linker and for
232           ELF targeted ports.  For i386 PE, symbols explicitly listed in a
233           .def file are still exported, regardless of this option.  For ELF
234           targeted ports, symbols affected by this option will be treated as
235           hidden.
236
237       --exclude-modules-for-implib module,module,...
238           Specifies a list of object files or archive members, from which
239           symbols should not be automatically exported, but which should be
240           copied wholesale into the import library being generated during the
241           link.  The module names may be delimited by commas or colons, and
242           must match exactly the filenames used by ld to open the files; for
243           archive members, this is simply the member name, but for object
244           files the name listed must include and match precisely any path
245           used to specify the input file on the linker's command-line.  This
246           option is available only for the i386 PE targeted port of the
247           linker.  Symbols explicitly listed in a .def file are still
248           exported, regardless of this option.
249
250       -E
251       --export-dynamic
252       --no-export-dynamic
253           When creating a dynamically linked executable, using the -E option
254           or the --export-dynamic option causes the linker to add all symbols
255           to the dynamic symbol table.  The dynamic symbol table is the set
256           of symbols which are visible from dynamic objects at run time.
257
258           If you do not use either of these options (or use the
259           --no-export-dynamic option to restore the default behavior), the
260           dynamic symbol table will normally contain only those symbols which
261           are referenced by some dynamic object mentioned in the link.
262
263           If you use "dlopen" to load a dynamic object which needs to refer
264           back to the symbols defined by the program, rather than some other
265           dynamic object, then you will probably need to use this option when
266           linking the program itself.
267
268           You can also use the dynamic list to control what symbols should be
269           added to the dynamic symbol table if the output format supports it.
270           See the description of --dynamic-list.
271
272           Note that this option is specific to ELF targeted ports.  PE
273           targets support a similar function to export all symbols from a DLL
274           or EXE; see the description of --export-all-symbols below.
275
276       -EB Link big-endian objects.  This affects the default output format.
277
278       -EL Link little-endian objects.  This affects the default output
279           format.
280
281       -f name
282       --auxiliary=name
283           When creating an ELF shared object, set the internal DT_AUXILIARY
284           field to the specified name.  This tells the dynamic linker that
285           the symbol table of the shared object should be used as an
286           auxiliary filter on the symbol table of the shared object name.
287
288           If you later link a program against this filter object, then, when
289           you run the program, the dynamic linker will see the DT_AUXILIARY
290           field.  If the dynamic linker resolves any symbols from the filter
291           object, it will first check whether there is a definition in the
292           shared object name.  If there is one, it will be used instead of
293           the definition in the filter object.  The shared object name need
294           not exist.  Thus the shared object name may be used to provide an
295           alternative implementation of certain functions, perhaps for
296           debugging or for machine specific performance.
297
298           This option may be specified more than once.  The DT_AUXILIARY
299           entries will be created in the order in which they appear on the
300           command line.
301
302       -F name
303       --filter=name
304           When creating an ELF shared object, set the internal DT_FILTER
305           field to the specified name.  This tells the dynamic linker that
306           the symbol table of the shared object which is being created should
307           be used as a filter on the symbol table of the shared object name.
308
309           If you later link a program against this filter object, then, when
310           you run the program, the dynamic linker will see the DT_FILTER
311           field.  The dynamic linker will resolve symbols according to the
312           symbol table of the filter object as usual, but it will actually
313           link to the definitions found in the shared object name.  Thus the
314           filter object can be used to select a subset of the symbols
315           provided by the object name.
316
317           Some older linkers used the -F option throughout a compilation
318           toolchain for specifying object-file format for both input and
319           output object files.  The GNU linker uses other mechanisms for this
320           purpose: the -b, --format, --oformat options, the "TARGET" command
321           in linker scripts, and the "GNUTARGET" environment variable.  The
322           GNU linker will ignore the -F option when not creating an ELF
323           shared object.
324
325       -fini=name
326           When creating an ELF executable or shared object, call NAME when
327           the executable or shared object is unloaded, by setting DT_FINI to
328           the address of the function.  By default, the linker uses "_fini"
329           as the function to call.
330
331       -g  Ignored.  Provided for compatibility with other tools.
332
333       -G value
334       --gpsize=value
335           Set the maximum size of objects to be optimized using the GP
336           register to size.  This is only meaningful for object file formats
337           such as MIPS ELF that support putting large and small objects into
338           different sections.  This is ignored for other object file formats.
339
340       -h name
341       -soname=name
342           When creating an ELF shared object, set the internal DT_SONAME
343           field to the specified name.  When an executable is linked with a
344           shared object which has a DT_SONAME field, then when the executable
345           is run the dynamic linker will attempt to load the shared object
346           specified by the DT_SONAME field rather than the using the file
347           name given to the linker.
348
349       -i  Perform an incremental link (same as option -r).
350
351       -init=name
352           When creating an ELF executable or shared object, call NAME when
353           the executable or shared object is loaded, by setting DT_INIT to
354           the address of the function.  By default, the linker uses "_init"
355           as the function to call.
356
357       -l namespec
358       --library=namespec
359           Add the archive or object file specified by namespec to the list of
360           files to link.  This option may be used any number of times.  If
361           namespec is of the form :filename, ld will search the library path
362           for a file called filename, otherwise it will search the library
363           path for a file called libnamespec.a.
364
365           On systems which support shared libraries, ld may also search for
366           files other than libnamespec.a.  Specifically, on ELF and SunOS
367           systems, ld will search a directory for a library called
368           libnamespec.so before searching for one called libnamespec.a.  (By
369           convention, a ".so" extension indicates a shared library.)  Note
370           that this behavior does not apply to :filename, which always
371           specifies a file called filename.
372
373           The linker will search an archive only once, at the location where
374           it is specified on the command line.  If the archive defines a
375           symbol which was undefined in some object which appeared before the
376           archive on the command line, the linker will include the
377           appropriate file(s) from the archive.  However, an undefined symbol
378           in an object appearing later on the command line will not cause the
379           linker to search the archive again.
380
381           See the -( option for a way to force the linker to search archives
382           multiple times.
383
384           You may list the same archive multiple times on the command line.
385
386           This type of archive searching is standard for Unix linkers.
387           However, if you are using ld on AIX, note that it is different from
388           the behaviour of the AIX linker.
389
390       -L searchdir
391       --library-path=searchdir
392           Add path searchdir to the list of paths that ld will search for
393           archive libraries and ld control scripts.  You may use this option
394           any number of times.  The directories are searched in the order in
395           which they are specified on the command line.  Directories
396           specified on the command line are searched before the default
397           directories.  All -L options apply to all -l options, regardless of
398           the order in which the options appear.  -L options do not affect
399           how ld searches for a linker script unless -T option is specified.
400
401           If searchdir begins with "=" or $SYSROOT, then this prefix will be
402           replaced by the sysroot prefix, controlled by the --sysroot option,
403           or specified when the linker is configured.
404
405           The default set of paths searched (without being specified with -L)
406           depends on which emulation mode ld is using, and in some cases also
407           on how it was configured.
408
409           The paths can also be specified in a link script with the
410           "SEARCH_DIR" command.  Directories specified this way are searched
411           at the point in which the linker script appears in the command
412           line.
413
414       -m emulation
415           Emulate the emulation linker.  You can list the available
416           emulations with the --verbose or -V options.
417
418           If the -m option is not used, the emulation is taken from the
419           "LDEMULATION" environment variable, if that is defined.
420
421           Otherwise, the default emulation depends upon how the linker was
422           configured.
423
424       -M
425       --print-map
426           Print a link map to the standard output.  A link map provides
427           information about the link, including the following:
428
429           ·   Where object files are mapped into memory.
430
431           ·   How common symbols are allocated.
432
433           ·   All archive members included in the link, with a mention of the
434               symbol which caused the archive member to be brought in.
435
436           ·   The values assigned to symbols.
437
438               Note - symbols whose values are computed by an expression which
439               involves a reference to a previous value of the same symbol may
440               not have correct result displayed in the link map.  This is
441               because the linker discards intermediate results and only
442               retains the final value of an expression.  Under such
443               circumstances the linker will display the final value enclosed
444               by square brackets.  Thus for example a linker script
445               containing:
446
447                          foo = 1
448                          foo = foo * 4
449                          foo = foo + 8
450
451               will produce the following output in the link map if the -M
452               option is used:
453
454                          0x00000001                foo = 0x1
455                          [0x0000000c]                foo = (foo * 0x4)
456                          [0x0000000c]                foo = (foo + 0x8)
457
458               See Expressions for more information about expressions in
459               linker scripts.
460
461       -n
462       --nmagic
463           Turn off page alignment of sections, and disable linking against
464           shared libraries.  If the output format supports Unix style magic
465           numbers, mark the output as "NMAGIC".
466
467       -N
468       --omagic
469           Set the text and data sections to be readable and writable.  Also,
470           do not page-align the data segment, and disable linking against
471           shared libraries.  If the output format supports Unix style magic
472           numbers, mark the output as "OMAGIC". Note: Although a writable
473           text section is allowed for PE-COFF targets, it does not conform to
474           the format specification published by Microsoft.
475
476       --no-omagic
477           This option negates most of the effects of the -N option.  It sets
478           the text section to be read-only, and forces the data segment to be
479           page-aligned.  Note - this option does not enable linking against
480           shared libraries.  Use -Bdynamic for this.
481
482       -o output
483       --output=output
484           Use output as the name for the program produced by ld; if this
485           option is not specified, the name a.out is used by default.  The
486           script command "OUTPUT" can also specify the output file name.
487
488       -O level
489           If level is a numeric values greater than zero ld optimizes the
490           output.  This might take significantly longer and therefore
491           probably should only be enabled for the final binary.  At the
492           moment this option only affects ELF shared library generation.
493           Future releases of the linker may make more use of this option.
494           Also currently there is no difference in the linker's behaviour for
495           different non-zero values of this option.  Again this may change
496           with future releases.
497
498       -plugin name
499           Involve a plugin in the linking process.  The name parameter is the
500           absolute filename of the plugin.  Usually this parameter is
501           automatically added by the complier, when using link time
502           optimization, but users can also add their own plugins if they so
503           wish.
504
505           Note that the location of the compiler originated plugins is
506           different from the place where the ar, nm and ranlib programs
507           search for their plugins.  In order for those commands to make use
508           of a compiler based plugin it must first be copied into the
509           ${libdir}/bfd-plugins directory.  All gcc based linker plugins are
510           backward compatible, so it is sufficient to just copy in the newest
511           one.
512
513       --push-state
514           The --push-state allows to preserve the current state of the flags
515           which govern the input file handling so that they can all be
516           restored with one corresponding --pop-state option.
517
518           The option which are covered are: -Bdynamic, -Bstatic, -dn, -dy,
519           -call_shared, -non_shared, -static, -N, -n, --whole-archive,
520           --no-whole-archive, -r, -Ur, --copy-dt-needed-entries,
521           --no-copy-dt-needed-entries, --as-needed, --no-as-needed, and -a.
522
523           One target for this option are specifications for pkg-config.  When
524           used with the --libs option all possibly needed libraries are
525           listed and then possibly linked with all the time.  It is better to
526           return something as follows:
527
528                   -Wl,--push-state,--as-needed -libone -libtwo -Wl,--pop-state
529
530       --pop-state
531           Undoes the effect of --push-state, restores the previous values of
532           the flags governing input file handling.
533
534       -q
535       --emit-relocs
536           Leave relocation sections and contents in fully linked executables.
537           Post link analysis and optimization tools may need this information
538           in order to perform correct modifications of executables.  This
539           results in larger executables.
540
541           This option is currently only supported on ELF platforms.
542
543       --force-dynamic
544           Force the output file to have dynamic sections.  This option is
545           specific to VxWorks targets.
546
547       -r
548       --relocatable
549           Generate relocatable output---i.e., generate an output file that
550           can in turn serve as input to ld.  This is often called partial
551           linking.  As a side effect, in environments that support standard
552           Unix magic numbers, this option also sets the output file's magic
553           number to "OMAGIC".  If this option is not specified, an absolute
554           file is produced.  When linking C++ programs, this option will not
555           resolve references to constructors; to do that, use -Ur.
556
557           When an input file does not have the same format as the output
558           file, partial linking is only supported if that input file does not
559           contain any relocations.  Different output formats can have further
560           restrictions; for example some "a.out"-based formats do not support
561           partial linking with input files in other formats at all.
562
563           This option does the same thing as -i.
564
565       -R filename
566       --just-symbols=filename
567           Read symbol names and their addresses from filename, but do not
568           relocate it or include it in the output.  This allows your output
569           file to refer symbolically to absolute locations of memory defined
570           in other programs.  You may use this option more than once.
571
572           For compatibility with other ELF linkers, if the -R option is
573           followed by a directory name, rather than a file name, it is
574           treated as the -rpath option.
575
576       -s
577       --strip-all
578           Omit all symbol information from the output file.
579
580       -S
581       --strip-debug
582           Omit debugger symbol information (but not all symbols) from the
583           output file.
584
585       --strip-discarded
586       --no-strip-discarded
587           Omit (or do not omit) global symbols defined in discarded sections.
588           Enabled by default.
589
590       -t
591       --trace
592           Print the names of the input files as ld processes them.
593
594       -T scriptfile
595       --script=scriptfile
596           Use scriptfile as the linker script.  This script replaces ld's
597           default linker script (rather than adding to it), so commandfile
598           must specify everything necessary to describe the output file.
599           If scriptfile does not exist in the current directory, "ld" looks
600           for it in the directories specified by any preceding -L options.
601           Multiple -T options accumulate.
602
603       -dT scriptfile
604       --default-script=scriptfile
605           Use scriptfile as the default linker script.
606
607           This option is similar to the --script option except that
608           processing of the script is delayed until after the rest of the
609           command line has been processed.  This allows options placed after
610           the --default-script option on the command line to affect the
611           behaviour of the linker script, which can be important when the
612           linker command line cannot be directly controlled by the user.  (eg
613           because the command line is being constructed by another tool, such
614           as gcc).
615
616       -u symbol
617       --undefined=symbol
618           Force symbol to be entered in the output file as an undefined
619           symbol.  Doing this may, for example, trigger linking of additional
620           modules from standard libraries.  -u may be repeated with different
621           option arguments to enter additional undefined symbols.  This
622           option is equivalent to the "EXTERN" linker script command.
623
624           If this option is being used to force additional modules to be
625           pulled into the link, and if it is an error for the symbol to
626           remain undefined, then the option --require-defined should be used
627           instead.
628
629       --require-defined=symbol
630           Require that symbol is defined in the output file.  This option is
631           the same as option --undefined except that if symbol is not defined
632           in the output file then the linker will issue an error and exit.
633           The same effect can be achieved in a linker script by using
634           "EXTERN", "ASSERT" and "DEFINED" together.  This option can be used
635           multiple times to require additional symbols.
636
637       -Ur For anything other than C++ programs, this option is equivalent to
638           -r: it generates relocatable output---i.e., an output file that can
639           in turn serve as input to ld.  When linking C++ programs, -Ur does
640           resolve references to constructors, unlike -r.  It does not work to
641           use -Ur on files that were themselves linked with -Ur; once the
642           constructor table has been built, it cannot be added to.  Use -Ur
643           only for the last partial link, and -r for the others.
644
645       --orphan-handling=MODE
646           Control how orphan sections are handled.  An orphan section is one
647           not specifically mentioned in a linker script.
648
649           MODE can have any of the following values:
650
651           "place"
652               Orphan sections are placed into a suitable output section
653               following the strategy described in Orphan Sections.  The
654               option --unique also affects how sections are placed.
655
656           "discard"
657               All orphan sections are discarded, by placing them in the
658               /DISCARD/ section.
659
660           "warn"
661               The linker will place the orphan section as for "place" and
662               also issue a warning.
663
664           "error"
665               The linker will exit with an error if any orphan section is
666               found.
667
668           The default if --orphan-handling is not given is "place".
669
670       --unique[=SECTION]
671           Creates a separate output section for every input section matching
672           SECTION, or if the optional wildcard SECTION argument is missing,
673           for every orphan input section.  An orphan section is one not
674           specifically mentioned in a linker script.  You may use this option
675           multiple times on the command line;  It prevents the normal merging
676           of input sections with the same name, overriding output section
677           assignments in a linker script.
678
679       -v
680       --version
681       -V  Display the version number for ld.  The -V option also lists the
682           supported emulations.
683
684       -x
685       --discard-all
686           Delete all local symbols.
687
688       -X
689       --discard-locals
690           Delete all temporary local symbols.  (These symbols start with
691           system-specific local label prefixes, typically .L for ELF systems
692           or L for traditional a.out systems.)
693
694       -y symbol
695       --trace-symbol=symbol
696           Print the name of each linked file in which symbol appears.  This
697           option may be given any number of times.  On many systems it is
698           necessary to prepend an underscore.
699
700           This option is useful when you have an undefined symbol in your
701           link but don't know where the reference is coming from.
702
703       -Y path
704           Add path to the default library search path.  This option exists
705           for Solaris compatibility.
706
707       -z keyword
708           The recognized keywords are:
709
710           bndplt
711               Always generate BND prefix in PLT entries. Supported for
712               Linux/x86_64.
713
714           call-nop=prefix-addr
715           call-nop=suffix-nop
716           call-nop=prefix-byte
717           call-nop=suffix-byte
718               Specify the 1-byte "NOP" padding when transforming indirect
719               call to a locally defined function, foo, via its GOT slot.
720               call-nop=prefix-addr generates "0x67 call foo".
721               call-nop=suffix-nop generates "call foo 0x90".
722               call-nop=prefix-byte generates "byte call foo".
723               call-nop=suffix-byte generates "call foo byte".  Supported for
724               i386 and x86_64.
725
726           combreloc
727           nocombreloc
728               Combine multiple dynamic relocation sections and sort to
729               improve dynamic symbol lookup caching.  Do not do this if
730               nocombreloc.
731
732           common
733           nocommon
734               Generate common symbols with STT_COMMON type during a
735               relocatable link.  Use STT_OBJECT type if nocommon.
736
737           common-page-size=value
738               Set the page size most commonly used to value.  Memory image
739               layout will be optimized to minimize memory pages if the system
740               is using pages of this size.
741
742           defs
743               Report unresolved symbol references from regular object files.
744               This is done even if the linker is creating a non-symbolic
745               shared library.  This option is the inverse of -z undefs.
746
747           dynamic-undefined-weak
748           nodynamic-undefined-weak
749               Make undefined weak symbols dynamic when building a dynamic
750               object, if they are referenced from a regular object file and
751               not forced local by symbol visibility or versioning.  Do not
752               make them dynamic if nodynamic-undefined-weak.  If neither
753               option is given, a target may default to either option being in
754               force, or make some other selection of undefined weak symbols
755               dynamic.  Not all targets support these options.
756
757           execstack
758               Marks the object as requiring executable stack.
759
760           global
761               This option is only meaningful when building a shared object.
762               It makes the symbols defined by this shared object available
763               for symbol resolution of subsequently loaded libraries.
764
765           globalaudit
766               This option is only meaningful when building a dynamic
767               executable.  This option marks the executable as requiring
768               global auditing by setting the "DF_1_GLOBAUDIT" bit in the
769               "DT_FLAGS_1" dynamic tag.  Global auditing requires that any
770               auditing library defined via the --depaudit or -P command line
771               options be run for all dynamic objects loaded by the
772               application.
773
774           ibtplt
775               Generate Intel Indirect Branch Tracking (IBT) enabled PLT
776               entries.  Supported for Linux/i386 and Linux/x86_64.
777
778           ibt Generate GNU_PROPERTY_X86_FEATURE_1_IBT in .note.gnu.property
779               section to indicate compatibility with IBT.  This also implies
780               ibtplt.  Supported for Linux/i386 and Linux/x86_64.
781
782           initfirst
783               This option is only meaningful when building a shared object.
784               It marks the object so that its runtime initialization will
785               occur before the runtime initialization of any other objects
786               brought into the process at the same time.  Similarly the
787               runtime finalization of the object will occur after the runtime
788               finalization of any other objects.
789
790           interpose
791               Specify that the dynamic loader should modify its symbol search
792               order so that symbols in this shared library interpose all
793               other shared libraries not so marked.
794
795           lazy
796               When generating an executable or shared library, mark it to
797               tell the dynamic linker to defer function call resolution to
798               the point when the function is called (lazy binding), rather
799               than at load time.  Lazy binding is the default.
800
801           loadfltr
802               Specify that the object's filters be processed immediately at
803               runtime.
804
805           max-page-size=value
806               Set the maximum memory page size supported to value.
807
808           muldefs
809               Allow multiple definitions.
810
811           nocopyreloc
812               Disable linker generated .dynbss variables used in place of
813               variables defined in shared libraries.  May result in dynamic
814               text relocations.
815
816           nodefaultlib
817               Specify that the dynamic loader search for dependencies of this
818               object should ignore any default library search paths.
819
820           nodelete
821               Specify that the object shouldn't be unloaded at runtime.
822
823           nodlopen
824               Specify that the object is not available to "dlopen".
825
826           nodump
827               Specify that the object can not be dumped by "dldump".
828
829           noexecstack
830               Marks the object as not requiring executable stack.
831
832           noextern-protected-data
833               Don't treat protected data symbols as external when building a
834               shared library.  This option overrides the linker backend
835               default.  It can be used to work around incorrect relocations
836               against protected data symbols generated by compiler.  Updates
837               on protected data symbols by another module aren't visible to
838               the resulting shared library.  Supported for i386 and x86-64.
839
840           noreloc-overflow
841               Disable relocation overflow check.  This can be used to disable
842               relocation overflow check if there will be no dynamic
843               relocation overflow at run-time.  Supported for x86_64.
844
845           now When generating an executable or shared library, mark it to
846               tell the dynamic linker to resolve all symbols when the program
847               is started, or when the shared library is loaded by dlopen,
848               instead of deferring function call resolution to the point when
849               the function is first called.
850
851           origin
852               Specify that the object requires $ORIGIN handling in paths.
853
854           relro
855           norelro
856               Create an ELF "PT_GNU_RELRO" segment header in the object.
857               This specifies a memory segment that should be made read-only
858               after relocation, if supported.  Specifying common-page-size
859               smaller than the system page size will render this protection
860               ineffective.  Don't create an ELF "PT_GNU_RELRO" segment if
861               norelro.
862
863           separate-code
864           noseparate-code
865               Create separate code "PT_LOAD" segment header in the object.
866               This specifies a memory segment that should contain only
867               instructions and must be in wholly disjoint pages from any
868               other data.  Don't create separate code "PT_LOAD" segment if
869               noseparate-code is used.
870
871           shstk
872               Generate GNU_PROPERTY_X86_FEATURE_1_SHSTK in .note.gnu.property
873               section to indicate compatibility with Intel Shadow Stack.
874               Supported for Linux/i386 and Linux/x86_64.
875
876           stack-size=value
877               Specify a stack size for an ELF "PT_GNU_STACK" segment.
878               Specifying zero will override any default non-zero sized
879               "PT_GNU_STACK" segment creation.
880
881           text
882           notext
883           textoff
884               Report an error if DT_TEXTREL is set, i.e., if the binary has
885               dynamic relocations in read-only sections.  Don't report an
886               error if notext or textoff.
887
888           undefs
889               Do not report unresolved symbol references from regular object
890               files, either when creating an executable, or when creating a
891               shared library.  This option is the inverse of -z defs.
892
893           Other keywords are ignored for Solaris compatibility.
894
895       -( archives -)
896       --start-group archives --end-group
897           The archives should be a list of archive files.  They may be either
898           explicit file names, or -l options.
899
900           The specified archives are searched repeatedly until no new
901           undefined references are created.  Normally, an archive is searched
902           only once in the order that it is specified on the command line.
903           If a symbol in that archive is needed to resolve an undefined
904           symbol referred to by an object in an archive that appears later on
905           the command line, the linker would not be able to resolve that
906           reference.  By grouping the archives, they all be searched
907           repeatedly until all possible references are resolved.
908
909           Using this option has a significant performance cost.  It is best
910           to use it only when there are unavoidable circular references
911           between two or more archives.
912
913       --accept-unknown-input-arch
914       --no-accept-unknown-input-arch
915           Tells the linker to accept input files whose architecture cannot be
916           recognised.  The assumption is that the user knows what they are
917           doing and deliberately wants to link in these unknown input files.
918           This was the default behaviour of the linker, before release 2.14.
919           The default behaviour from release 2.14 onwards is to reject such
920           input files, and so the --accept-unknown-input-arch option has been
921           added to restore the old behaviour.
922
923       --as-needed
924       --no-as-needed
925           This option affects ELF DT_NEEDED tags for dynamic libraries
926           mentioned on the command line after the --as-needed option.
927           Normally the linker will add a DT_NEEDED tag for each dynamic
928           library mentioned on the command line, regardless of whether the
929           library is actually needed or not.  --as-needed causes a DT_NEEDED
930           tag to only be emitted for a library that at that point in the link
931           satisfies a non-weak undefined symbol reference from a regular
932           object file or, if the library is not found in the DT_NEEDED lists
933           of other needed libraries, a non-weak undefined symbol reference
934           from another needed dynamic library.  Object files or libraries
935           appearing on the command line after the library in question do not
936           affect whether the library is seen as needed.  This is similar to
937           the rules for extraction of object files from archives.
938           --no-as-needed restores the default behaviour.
939
940       --add-needed
941       --no-add-needed
942           These two options have been deprecated because of the similarity of
943           their names to the --as-needed and --no-as-needed options.  They
944           have been replaced by --copy-dt-needed-entries and
945           --no-copy-dt-needed-entries.
946
947       -assert keyword
948           This option is ignored for SunOS compatibility.
949
950       -Bdynamic
951       -dy
952       -call_shared
953           Link against dynamic libraries.  This is only meaningful on
954           platforms for which shared libraries are supported.  This option is
955           normally the default on such platforms.  The different variants of
956           this option are for compatibility with various systems.  You may
957           use this option multiple times on the command line: it affects
958           library searching for -l options which follow it.
959
960       -Bgroup
961           Set the "DF_1_GROUP" flag in the "DT_FLAGS_1" entry in the dynamic
962           section.  This causes the runtime linker to handle lookups in this
963           object and its dependencies to be performed only inside the group.
964           --unresolved-symbols=report-all is implied.  This option is only
965           meaningful on ELF platforms which support shared libraries.
966
967       -Bstatic
968       -dn
969       -non_shared
970       -static
971           Do not link against shared libraries.  This is only meaningful on
972           platforms for which shared libraries are supported.  The different
973           variants of this option are for compatibility with various systems.
974           You may use this option multiple times on the command line: it
975           affects library searching for -l options which follow it.  This
976           option also implies --unresolved-symbols=report-all.  This option
977           can be used with -shared.  Doing so means that a shared library is
978           being created but that all of the library's external references
979           must be resolved by pulling in entries from static libraries.
980
981       -Bsymbolic
982           When creating a shared library, bind references to global symbols
983           to the definition within the shared library, if any.  Normally, it
984           is possible for a program linked against a shared library to
985           override the definition within the shared library.  This option can
986           also be used with the --export-dynamic option, when creating a
987           position independent executable, to bind references to global
988           symbols to the definition within the executable.  This option is
989           only meaningful on ELF platforms which support shared libraries and
990           position independent executables.
991
992       -Bsymbolic-functions
993           When creating a shared library, bind references to global function
994           symbols to the definition within the shared library, if any.  This
995           option can also be used with the --export-dynamic option, when
996           creating a position independent executable, to bind references to
997           global function symbols to the definition within the executable.
998           This option is only meaningful on ELF platforms which support
999           shared libraries and position independent executables.
1000
1001       --dynamic-list=dynamic-list-file
1002           Specify the name of a dynamic list file to the linker.  This is
1003           typically used when creating shared libraries to specify a list of
1004           global symbols whose references shouldn't be bound to the
1005           definition within the shared library, or creating dynamically
1006           linked executables to specify a list of symbols which should be
1007           added to the symbol table in the executable.  This option is only
1008           meaningful on ELF platforms which support shared libraries.
1009
1010           The format of the dynamic list is the same as the version node
1011           without scope and node name.  See VERSION for more information.
1012
1013       --dynamic-list-data
1014           Include all global data symbols to the dynamic list.
1015
1016       --dynamic-list-cpp-new
1017           Provide the builtin dynamic list for C++ operator new and delete.
1018           It is mainly useful for building shared libstdc++.
1019
1020       --dynamic-list-cpp-typeinfo
1021           Provide the builtin dynamic list for C++ runtime type
1022           identification.
1023
1024       --check-sections
1025       --no-check-sections
1026           Asks the linker not to check section addresses after they have been
1027           assigned to see if there are any overlaps.  Normally the linker
1028           will perform this check, and if it finds any overlaps it will
1029           produce suitable error messages.  The linker does know about, and
1030           does make allowances for sections in overlays.  The default
1031           behaviour can be restored by using the command line switch
1032           --check-sections.  Section overlap is not usually checked for
1033           relocatable links.  You can force checking in that case by using
1034           the --check-sections option.
1035
1036       --copy-dt-needed-entries
1037       --no-copy-dt-needed-entries
1038           This option affects the treatment of dynamic libraries referred to
1039           by DT_NEEDED tags inside ELF dynamic libraries mentioned on the
1040           command line.  Normally the linker won't add a DT_NEEDED tag to the
1041           output binary for each library mentioned in a DT_NEEDED tag in an
1042           input dynamic library.  With --copy-dt-needed-entries specified on
1043           the command line however any dynamic libraries that follow it will
1044           have their DT_NEEDED entries added.  The default behaviour can be
1045           restored with --no-copy-dt-needed-entries.
1046
1047           This option also has an effect on the resolution of symbols in
1048           dynamic libraries.  With --copy-dt-needed-entries dynamic libraries
1049           mentioned on the command line will be recursively searched,
1050           following their DT_NEEDED tags to other libraries, in order to
1051           resolve symbols required by the output binary.  With the default
1052           setting however the searching of dynamic libraries that follow it
1053           will stop with the dynamic library itself.  No DT_NEEDED links will
1054           be traversed to resolve symbols.
1055
1056       --cref
1057           Output a cross reference table.  If a linker map file is being
1058           generated, the cross reference table is printed to the map file.
1059           Otherwise, it is printed on the standard output.
1060
1061           The format of the table is intentionally simple, so that it may be
1062           easily processed by a script if necessary.  The symbols are printed
1063           out, sorted by name.  For each symbol, a list of file names is
1064           given.  If the symbol is defined, the first file listed is the
1065           location of the definition.  If the symbol is defined as a common
1066           value then any files where this happens appear next.  Finally any
1067           files that reference the symbol are listed.
1068
1069       --no-define-common
1070           This option inhibits the assignment of addresses to common symbols.
1071           The script command "INHIBIT_COMMON_ALLOCATION" has the same effect.
1072
1073           The --no-define-common option allows decoupling the decision to
1074           assign addresses to Common symbols from the choice of the output
1075           file type; otherwise a non-Relocatable output type forces assigning
1076           addresses to Common symbols.  Using --no-define-common allows
1077           Common symbols that are referenced from a shared library to be
1078           assigned addresses only in the main program.  This eliminates the
1079           unused duplicate space in the shared library, and also prevents any
1080           possible confusion over resolving to the wrong duplicate when there
1081           are many dynamic modules with specialized search paths for runtime
1082           symbol resolution.
1083
1084       --force-group-allocation
1085           This option causes the linker to place section group members like
1086           normal input sections, and to delete the section groups.  This is
1087           the default behaviour for a final link but this option can be used
1088           to change the behaviour of a relocatable link (-r).  The script
1089           command "FORCE_GROUP_ALLOCATION" has the same effect.
1090
1091       --defsym=symbol=expression
1092           Create a global symbol in the output file, containing the absolute
1093           address given by expression.  You may use this option as many times
1094           as necessary to define multiple symbols in the command line.  A
1095           limited form of arithmetic is supported for the expression in this
1096           context: you may give a hexadecimal constant or the name of an
1097           existing symbol, or use "+" and "-" to add or subtract hexadecimal
1098           constants or symbols.  If you need more elaborate expressions,
1099           consider using the linker command language from a script.  Note:
1100           there should be no white space between symbol, the equals sign
1101           ("="), and expression.
1102
1103       --demangle[=style]
1104       --no-demangle
1105           These options control whether to demangle symbol names in error
1106           messages and other output.  When the linker is told to demangle, it
1107           tries to present symbol names in a readable fashion: it strips
1108           leading underscores if they are used by the object file format, and
1109           converts C++ mangled symbol names into user readable names.
1110           Different compilers have different mangling styles.  The optional
1111           demangling style argument can be used to choose an appropriate
1112           demangling style for your compiler.  The linker will demangle by
1113           default unless the environment variable COLLECT_NO_DEMANGLE is set.
1114           These options may be used to override the default.
1115
1116       -Ifile
1117       --dynamic-linker=file
1118           Set the name of the dynamic linker.  This is only meaningful when
1119           generating dynamically linked ELF executables.  The default dynamic
1120           linker is normally correct; don't use this unless you know what you
1121           are doing.
1122
1123       --no-dynamic-linker
1124           When producing an executable file, omit the request for a dynamic
1125           linker to be used at load-time.  This is only meaningful for ELF
1126           executables that contain dynamic relocations, and usually requires
1127           entry point code that is capable of processing these relocations.
1128
1129       --embedded-relocs
1130           This option is similar to the --emit-relocs option except that the
1131           relocs are stored in a target specific section.  This option is
1132           only supported by the BFIN, CR16 and M68K targets.
1133
1134       --fatal-warnings
1135       --no-fatal-warnings
1136           Treat all warnings as errors.  The default behaviour can be
1137           restored with the option --no-fatal-warnings.
1138
1139       --force-exe-suffix
1140           Make sure that an output file has a .exe suffix.
1141
1142           If a successfully built fully linked output file does not have a
1143           ".exe" or ".dll" suffix, this option forces the linker to copy the
1144           output file to one of the same name with a ".exe" suffix. This
1145           option is useful when using unmodified Unix makefiles on a
1146           Microsoft Windows host, since some versions of Windows won't run an
1147           image unless it ends in a ".exe" suffix.
1148
1149       --gc-sections
1150       --no-gc-sections
1151           Enable garbage collection of unused input sections.  It is ignored
1152           on targets that do not support this option.  The default behaviour
1153           (of not performing this garbage collection) can be restored by
1154           specifying --no-gc-sections on the command line.  Note that garbage
1155           collection for COFF and PE format targets is supported, but the
1156           implementation is currently considered to be experimental.
1157
1158           --gc-sections decides which input sections are used by examining
1159           symbols and relocations.  The section containing the entry symbol
1160           and all sections containing symbols undefined on the command-line
1161           will be kept, as will sections containing symbols referenced by
1162           dynamic objects.  Note that when building shared libraries, the
1163           linker must assume that any visible symbol is referenced.  Once
1164           this initial set of sections has been determined, the linker
1165           recursively marks as used any section referenced by their
1166           relocations.  See --entry and --undefined.
1167
1168           This option can be set when doing a partial link (enabled with
1169           option -r).  In this case the root of symbols kept must be
1170           explicitly specified either by an --entry or --undefined option or
1171           by a "ENTRY" command in the linker script.
1172
1173       --print-gc-sections
1174       --no-print-gc-sections
1175           List all sections removed by garbage collection.  The listing is
1176           printed on stderr.  This option is only effective if garbage
1177           collection has been enabled via the --gc-sections) option.  The
1178           default behaviour (of not listing the sections that are removed)
1179           can be restored by specifying --no-print-gc-sections on the command
1180           line.
1181
1182       --gc-keep-exported
1183           When --gc-sections is enabled, this option prevents garbage
1184           collection of unused input sections that contain global symbols
1185           having default or protected visibility.  This option is intended to
1186           be used for executables where unreferenced sections would otherwise
1187           be garbage collected regardless of the external visibility of
1188           contained symbols.  Note that this option has no effect when
1189           linking shared objects since it is already the default behaviour.
1190           This option is only supported for ELF format targets.
1191
1192       --print-output-format
1193           Print the name of the default output format (perhaps influenced by
1194           other command-line options).  This is the string that would appear
1195           in an "OUTPUT_FORMAT" linker script command.
1196
1197       --print-memory-usage
1198           Print used size, total size and used size of memory regions created
1199           with the MEMORY command.  This is useful on embedded targets to
1200           have a quick view of amount of free memory.  The format of the
1201           output has one headline and one line per region.  It is both human
1202           readable and easily parsable by tools.  Here is an example of an
1203           output:
1204
1205                   Memory region         Used Size  Region Size  %age Used
1206                                ROM:        256 KB         1 MB     25.00%
1207                                RAM:          32 B         2 GB      0.00%
1208
1209       --help
1210           Print a summary of the command-line options on the standard output
1211           and exit.
1212
1213       --target-help
1214           Print a summary of all target specific options on the standard
1215           output and exit.
1216
1217       -Map=mapfile
1218           Print a link map to the file mapfile.  See the description of the
1219           -M option, above.
1220
1221       --no-keep-memory
1222           ld normally optimizes for speed over memory usage by caching the
1223           symbol tables of input files in memory.  This option tells ld to
1224           instead optimize for memory usage, by rereading the symbol tables
1225           as necessary.  This may be required if ld runs out of memory space
1226           while linking a large executable.
1227
1228       --no-undefined
1229       -z defs
1230           Report unresolved symbol references from regular object files.
1231           This is done even if the linker is creating a non-symbolic shared
1232           library.  The switch --[no-]allow-shlib-undefined controls the
1233           behaviour for reporting unresolved references found in shared
1234           libraries being linked in.
1235
1236           The effects of this option can be reverted by using "-z undefs".
1237
1238       --allow-multiple-definition
1239       -z muldefs
1240           Normally when a symbol is defined multiple times, the linker will
1241           report a fatal error. These options allow multiple definitions and
1242           the first definition will be used.
1243
1244       --allow-shlib-undefined
1245       --no-allow-shlib-undefined
1246           Allows or disallows undefined symbols in shared libraries.  This
1247           switch is similar to --no-undefined except that it determines the
1248           behaviour when the undefined symbols are in a shared library rather
1249           than a regular object file.  It does not affect how undefined
1250           symbols in regular object files are handled.
1251
1252           The default behaviour is to report errors for any undefined symbols
1253           referenced in shared libraries if the linker is being used to
1254           create an executable, but to allow them if the linker is being used
1255           to create a shared library.
1256
1257           The reasons for allowing undefined symbol references in shared
1258           libraries specified at link time are that:
1259
1260           ·   A shared library specified at link time may not be the same as
1261               the one that is available at load time, so the symbol might
1262               actually be resolvable at load time.
1263
1264           ·   There are some operating systems, eg BeOS and HPPA, where
1265               undefined symbols in shared libraries are normal.
1266
1267               The BeOS kernel for example patches shared libraries at load
1268               time to select whichever function is most appropriate for the
1269               current architecture.  This is used, for example, to
1270               dynamically select an appropriate memset function.
1271
1272       --no-undefined-version
1273           Normally when a symbol has an undefined version, the linker will
1274           ignore it. This option disallows symbols with undefined version and
1275           a fatal error will be issued instead.
1276
1277       --default-symver
1278           Create and use a default symbol version (the soname) for
1279           unversioned exported symbols.
1280
1281       --default-imported-symver
1282           Create and use a default symbol version (the soname) for
1283           unversioned imported symbols.
1284
1285       --no-warn-mismatch
1286           Normally ld will give an error if you try to link together input
1287           files that are mismatched for some reason, perhaps because they
1288           have been compiled for different processors or for different
1289           endiannesses.  This option tells ld that it should silently permit
1290           such possible errors.  This option should only be used with care,
1291           in cases when you have taken some special action that ensures that
1292           the linker errors are inappropriate.
1293
1294       --no-warn-search-mismatch
1295           Normally ld will give a warning if it finds an incompatible library
1296           during a library search.  This option silences the warning.
1297
1298       --no-whole-archive
1299           Turn off the effect of the --whole-archive option for subsequent
1300           archive files.
1301
1302       --noinhibit-exec
1303           Retain the executable output file whenever it is still usable.
1304           Normally, the linker will not produce an output file if it
1305           encounters errors during the link process; it exits without writing
1306           an output file when it issues any error whatsoever.
1307
1308       -nostdlib
1309           Only search library directories explicitly specified on the command
1310           line.  Library directories specified in linker scripts (including
1311           linker scripts specified on the command line) are ignored.
1312
1313       --oformat=output-format
1314           ld may be configured to support more than one kind of object file.
1315           If your ld is configured this way, you can use the --oformat option
1316           to specify the binary format for the output object file.  Even when
1317           ld is configured to support alternative object formats, you don't
1318           usually need to specify this, as ld should be configured to produce
1319           as a default output format the most usual format on each machine.
1320           output-format is a text string, the name of a particular format
1321           supported by the BFD libraries.  (You can list the available binary
1322           formats with objdump -i.)  The script command "OUTPUT_FORMAT" can
1323           also specify the output format, but this option overrides it.
1324
1325       --out-implib file
1326           Create an import library in file corresponding to the executable
1327           the linker is generating (eg. a DLL or ELF program).  This import
1328           library (which should be called "*.dll.a" or "*.a" for DLLs) may be
1329           used to link clients against the generated executable; this
1330           behaviour makes it possible to skip a separate import library
1331           creation step (eg. "dlltool" for DLLs).  This option is only
1332           available for the i386 PE and ELF targetted ports of the linker.
1333
1334       -pie
1335       --pic-executable
1336           Create a position independent executable.  This is currently only
1337           supported on ELF platforms.  Position independent executables are
1338           similar to shared libraries in that they are relocated by the
1339           dynamic linker to the virtual address the OS chooses for them
1340           (which can vary between invocations).  Like normal dynamically
1341           linked executables they can be executed and symbols defined in the
1342           executable cannot be overridden by shared libraries.
1343
1344       -qmagic
1345           This option is ignored for Linux compatibility.
1346
1347       -Qy This option is ignored for SVR4 compatibility.
1348
1349       --relax
1350       --no-relax
1351           An option with machine dependent effects.  This option is only
1352           supported on a few targets.
1353
1354           On some platforms the --relax option performs target specific,
1355           global optimizations that become possible when the linker resolves
1356           addressing in the program, such as relaxing address modes,
1357           synthesizing new instructions, selecting shorter version of current
1358           instructions, and combining constant values.
1359
1360           On some platforms these link time global optimizations may make
1361           symbolic debugging of the resulting executable impossible.  This is
1362           known to be the case for the Matsushita MN10200 and MN10300 family
1363           of processors.
1364
1365           On platforms where this is not supported, --relax is accepted, but
1366           ignored.
1367
1368           On platforms where --relax is accepted the option --no-relax can be
1369           used to disable the feature.
1370
1371       --retain-symbols-file=filename
1372           Retain only the symbols listed in the file filename, discarding all
1373           others.  filename is simply a flat file, with one symbol name per
1374           line.  This option is especially useful in environments (such as
1375           VxWorks) where a large global symbol table is accumulated
1376           gradually, to conserve run-time memory.
1377
1378           --retain-symbols-file does not discard undefined symbols, or
1379           symbols needed for relocations.
1380
1381           You may only specify --retain-symbols-file once in the command
1382           line.  It overrides -s and -S.
1383
1384       -rpath=dir
1385           Add a directory to the runtime library search path.  This is used
1386           when linking an ELF executable with shared objects.  All -rpath
1387           arguments are concatenated and passed to the runtime linker, which
1388           uses them to locate shared objects at runtime.  The -rpath option
1389           is also used when locating shared objects which are needed by
1390           shared objects explicitly included in the link; see the description
1391           of the -rpath-link option.  If -rpath is not used when linking an
1392           ELF executable, the contents of the environment variable
1393           "LD_RUN_PATH" will be used if it is defined.
1394
1395           The -rpath option may also be used on SunOS.  By default, on SunOS,
1396           the linker will form a runtime search path out of all the -L
1397           options it is given.  If a -rpath option is used, the runtime
1398           search path will be formed exclusively using the -rpath options,
1399           ignoring the -L options.  This can be useful when using gcc, which
1400           adds many -L options which may be on NFS mounted file systems.
1401
1402           For compatibility with other ELF linkers, if the -R option is
1403           followed by a directory name, rather than a file name, it is
1404           treated as the -rpath option.
1405
1406       -rpath-link=dir
1407           When using ELF or SunOS, one shared library may require another.
1408           This happens when an "ld -shared" link includes a shared library as
1409           one of the input files.
1410
1411           When the linker encounters such a dependency when doing a non-
1412           shared, non-relocatable link, it will automatically try to locate
1413           the required shared library and include it in the link, if it is
1414           not included explicitly.  In such a case, the -rpath-link option
1415           specifies the first set of directories to search.  The -rpath-link
1416           option may specify a sequence of directory names either by
1417           specifying a list of names separated by colons, or by appearing
1418           multiple times.
1419
1420           The tokens $ORIGIN and $LIB can appear in these search directories.
1421           They will be replaced by the full path to the directory containing
1422           the program or shared object in the case of $ORIGIN and either lib
1423           - for 32-bit binaries - or lib64 - for 64-bit binaries - in the
1424           case of $LIB.
1425
1426           The alternative form of these tokens - ${ORIGIN} and ${LIB} can
1427           also be used.  The token $PLATFORM is not supported.
1428
1429           This option should be used with caution as it overrides the search
1430           path that may have been hard compiled into a shared library. In
1431           such a case it is possible to use unintentionally a different
1432           search path than the runtime linker would do.
1433
1434           The linker uses the following search paths to locate required
1435           shared libraries:
1436
1437           1.  Any directories specified by -rpath-link options.
1438
1439           2.  Any directories specified by -rpath options.  The difference
1440               between -rpath and -rpath-link is that directories specified by
1441               -rpath options are included in the executable and used at
1442               runtime, whereas the -rpath-link option is only effective at
1443               link time. Searching -rpath in this way is only supported by
1444               native linkers and cross linkers which have been configured
1445               with the --with-sysroot option.
1446
1447           3.  On an ELF system, for native linkers, if the -rpath and
1448               -rpath-link options were not used, search the contents of the
1449               environment variable "LD_RUN_PATH".
1450
1451           4.  On SunOS, if the -rpath option was not used, search any
1452               directories specified using -L options.
1453
1454           5.  For a native linker, search the contents of the environment
1455               variable "LD_LIBRARY_PATH".
1456
1457           6.  For a native ELF linker, the directories in "DT_RUNPATH" or
1458               "DT_RPATH" of a shared library are searched for shared
1459               libraries needed by it. The "DT_RPATH" entries are ignored if
1460               "DT_RUNPATH" entries exist.
1461
1462           7.  The default directories, normally /lib and /usr/lib.
1463
1464           8.  For a native linker on an ELF system, if the file
1465               /etc/ld.so.conf exists, the list of directories found in that
1466               file.
1467
1468           If the required shared library is not found, the linker will issue
1469           a warning and continue with the link.
1470
1471       -shared
1472       -Bshareable
1473           Create a shared library.  This is currently only supported on ELF,
1474           XCOFF and SunOS platforms.  On SunOS, the linker will automatically
1475           create a shared library if the -e option is not used and there are
1476           undefined symbols in the link.
1477
1478       --sort-common
1479       --sort-common=ascending
1480       --sort-common=descending
1481           This option tells ld to sort the common symbols by alignment in
1482           ascending or descending order when it places them in the
1483           appropriate output sections.  The symbol alignments considered are
1484           sixteen-byte or larger, eight-byte, four-byte, two-byte, and one-
1485           byte. This is to prevent gaps between symbols due to alignment
1486           constraints.  If no sorting order is specified, then descending
1487           order is assumed.
1488
1489       --sort-section=name
1490           This option will apply "SORT_BY_NAME" to all wildcard section
1491           patterns in the linker script.
1492
1493       --sort-section=alignment
1494           This option will apply "SORT_BY_ALIGNMENT" to all wildcard section
1495           patterns in the linker script.
1496
1497       --spare-dynamic-tags=count
1498           This option specifies the number of empty slots to leave in the
1499           .dynamic section of ELF shared objects.  Empty slots may be needed
1500           by post processing tools, such as the prelinker.  The default is 5.
1501
1502       --split-by-file[=size]
1503           Similar to --split-by-reloc but creates a new output section for
1504           each input file when size is reached.  size defaults to a size of 1
1505           if not given.
1506
1507       --split-by-reloc[=count]
1508           Tries to creates extra sections in the output file so that no
1509           single output section in the file contains more than count
1510           relocations.  This is useful when generating huge relocatable files
1511           for downloading into certain real time kernels with the COFF object
1512           file format; since COFF cannot represent more than 65535
1513           relocations in a single section.  Note that this will fail to work
1514           with object file formats which do not support arbitrary sections.
1515           The linker will not split up individual input sections for
1516           redistribution, so if a single input section contains more than
1517           count relocations one output section will contain that many
1518           relocations.  count defaults to a value of 32768.
1519
1520       --stats
1521           Compute and display statistics about the operation of the linker,
1522           such as execution time and memory usage.
1523
1524       --sysroot=directory
1525           Use directory as the location of the sysroot, overriding the
1526           configure-time default.  This option is only supported by linkers
1527           that were configured using --with-sysroot.
1528
1529       --task-link
1530           This is used by COFF/PE based targets to create a task-linked
1531           object file where all of the global symbols have been converted to
1532           statics.
1533
1534       --traditional-format
1535           For some targets, the output of ld is different in some ways from
1536           the output of some existing linker.  This switch requests ld to use
1537           the traditional format instead.
1538
1539           For example, on SunOS, ld combines duplicate entries in the symbol
1540           string table.  This can reduce the size of an output file with full
1541           debugging information by over 30 percent.  Unfortunately, the SunOS
1542           "dbx" program can not read the resulting program ("gdb" has no
1543           trouble).  The --traditional-format switch tells ld to not combine
1544           duplicate entries.
1545
1546       --section-start=sectionname=org
1547           Locate a section in the output file at the absolute address given
1548           by org.  You may use this option as many times as necessary to
1549           locate multiple sections in the command line.  org must be a single
1550           hexadecimal integer; for compatibility with other linkers, you may
1551           omit the leading 0x usually associated with hexadecimal values.
1552           Note: there should be no white space between sectionname, the
1553           equals sign ("="), and org.
1554
1555       -Tbss=org
1556       -Tdata=org
1557       -Ttext=org
1558           Same as --section-start, with ".bss", ".data" or ".text" as the
1559           sectionname.
1560
1561       -Ttext-segment=org
1562           When creating an ELF executable, it will set the address of the
1563           first byte of the text segment.
1564
1565       -Trodata-segment=org
1566           When creating an ELF executable or shared object for a target where
1567           the read-only data is in its own segment separate from the
1568           executable text, it will set the address of the first byte of the
1569           read-only data segment.
1570
1571       -Tldata-segment=org
1572           When creating an ELF executable or shared object for x86-64 medium
1573           memory model, it will set the address of the first byte of the
1574           ldata segment.
1575
1576       --unresolved-symbols=method
1577           Determine how to handle unresolved symbols.  There are four
1578           possible values for method:
1579
1580           ignore-all
1581               Do not report any unresolved symbols.
1582
1583           report-all
1584               Report all unresolved symbols.  This is the default.
1585
1586           ignore-in-object-files
1587               Report unresolved symbols that are contained in shared
1588               libraries, but ignore them if they come from regular object
1589               files.
1590
1591           ignore-in-shared-libs
1592               Report unresolved symbols that come from regular object files,
1593               but ignore them if they come from shared libraries.  This can
1594               be useful when creating a dynamic binary and it is known that
1595               all the shared libraries that it should be referencing are
1596               included on the linker's command line.
1597
1598           The behaviour for shared libraries on their own can also be
1599           controlled by the --[no-]allow-shlib-undefined option.
1600
1601           Normally the linker will generate an error message for each
1602           reported unresolved symbol but the option --warn-unresolved-symbols
1603           can change this to a warning.
1604
1605       --dll-verbose
1606       --verbose[=NUMBER]
1607           Display the version number for ld and list the linker emulations
1608           supported.  Display which input files can and cannot be opened.
1609           Display the linker script being used by the linker. If the optional
1610           NUMBER argument > 1, plugin symbol status will also be displayed.
1611
1612       --version-script=version-scriptfile
1613           Specify the name of a version script to the linker.  This is
1614           typically used when creating shared libraries to specify additional
1615           information about the version hierarchy for the library being
1616           created.  This option is only fully supported on ELF platforms
1617           which support shared libraries; see VERSION.  It is partially
1618           supported on PE platforms, which can use version scripts to filter
1619           symbol visibility in auto-export mode: any symbols marked local in
1620           the version script will not be exported.
1621
1622       --warn-common
1623           Warn when a common symbol is combined with another common symbol or
1624           with a symbol definition.  Unix linkers allow this somewhat sloppy
1625           practice, but linkers on some other operating systems do not.  This
1626           option allows you to find potential problems from combining global
1627           symbols.  Unfortunately, some C libraries use this practice, so you
1628           may get some warnings about symbols in the libraries as well as in
1629           your programs.
1630
1631           There are three kinds of global symbols, illustrated here by C
1632           examples:
1633
1634           int i = 1;
1635               A definition, which goes in the initialized data section of the
1636               output file.
1637
1638           extern int i;
1639               An undefined reference, which does not allocate space.  There
1640               must be either a definition or a common symbol for the variable
1641               somewhere.
1642
1643           int i;
1644               A common symbol.  If there are only (one or more) common
1645               symbols for a variable, it goes in the uninitialized data area
1646               of the output file.  The linker merges multiple common symbols
1647               for the same variable into a single symbol.  If they are of
1648               different sizes, it picks the largest size.  The linker turns a
1649               common symbol into a declaration, if there is a definition of
1650               the same variable.
1651
1652           The --warn-common option can produce five kinds of warnings.  Each
1653           warning consists of a pair of lines: the first describes the symbol
1654           just encountered, and the second describes the previous symbol
1655           encountered with the same name.  One or both of the two symbols
1656           will be a common symbol.
1657
1658           1.  Turning a common symbol into a reference, because there is
1659               already a definition for the symbol.
1660
1661                       <file>(<section>): warning: common of `<symbol>'
1662                          overridden by definition
1663                       <file>(<section>): warning: defined here
1664
1665           2.  Turning a common symbol into a reference, because a later
1666               definition for the symbol is encountered.  This is the same as
1667               the previous case, except that the symbols are encountered in a
1668               different order.
1669
1670                       <file>(<section>): warning: definition of `<symbol>'
1671                          overriding common
1672                       <file>(<section>): warning: common is here
1673
1674           3.  Merging a common symbol with a previous same-sized common
1675               symbol.
1676
1677                       <file>(<section>): warning: multiple common
1678                          of `<symbol>'
1679                       <file>(<section>): warning: previous common is here
1680
1681           4.  Merging a common symbol with a previous larger common symbol.
1682
1683                       <file>(<section>): warning: common of `<symbol>'
1684                          overridden by larger common
1685                       <file>(<section>): warning: larger common is here
1686
1687           5.  Merging a common symbol with a previous smaller common symbol.
1688               This is the same as the previous case, except that the symbols
1689               are encountered in a different order.
1690
1691                       <file>(<section>): warning: common of `<symbol>'
1692                          overriding smaller common
1693                       <file>(<section>): warning: smaller common is here
1694
1695       --warn-constructors
1696           Warn if any global constructors are used.  This is only useful for
1697           a few object file formats.  For formats like COFF or ELF, the
1698           linker can not detect the use of global constructors.
1699
1700       --warn-multiple-gp
1701           Warn if multiple global pointer values are required in the output
1702           file.  This is only meaningful for certain processors, such as the
1703           Alpha.  Specifically, some processors put large-valued constants in
1704           a special section.  A special register (the global pointer) points
1705           into the middle of this section, so that constants can be loaded
1706           efficiently via a base-register relative addressing mode.  Since
1707           the offset in base-register relative mode is fixed and relatively
1708           small (e.g., 16 bits), this limits the maximum size of the constant
1709           pool.  Thus, in large programs, it is often necessary to use
1710           multiple global pointer values in order to be able to address all
1711           possible constants.  This option causes a warning to be issued
1712           whenever this case occurs.
1713
1714       --warn-once
1715           Only warn once for each undefined symbol, rather than once per
1716           module which refers to it.
1717
1718       --warn-section-align
1719           Warn if the address of an output section is changed because of
1720           alignment.  Typically, the alignment will be set by an input
1721           section.  The address will only be changed if it not explicitly
1722           specified; that is, if the "SECTIONS" command does not specify a
1723           start address for the section.
1724
1725       --warn-shared-textrel
1726           Warn if the linker adds a DT_TEXTREL to a shared object.
1727
1728       --warn-alternate-em
1729           Warn if an object has alternate ELF machine code.
1730
1731       --warn-unresolved-symbols
1732           If the linker is going to report an unresolved symbol (see the
1733           option --unresolved-symbols) it will normally generate an error.
1734           This option makes it generate a warning instead.
1735
1736       --error-unresolved-symbols
1737           This restores the linker's default behaviour of generating errors
1738           when it is reporting unresolved symbols.
1739
1740       --whole-archive
1741           For each archive mentioned on the command line after the
1742           --whole-archive option, include every object file in the archive in
1743           the link, rather than searching the archive for the required object
1744           files.  This is normally used to turn an archive file into a shared
1745           library, forcing every object to be included in the resulting
1746           shared library.  This option may be used more than once.
1747
1748           Two notes when using this option from gcc: First, gcc doesn't know
1749           about this option, so you have to use -Wl,-whole-archive.  Second,
1750           don't forget to use -Wl,-no-whole-archive after your list of
1751           archives, because gcc will add its own list of archives to your
1752           link and you may not want this flag to affect those as well.
1753
1754       --wrap=symbol
1755           Use a wrapper function for symbol.  Any undefined reference to
1756           symbol will be resolved to "__wrap_symbol".  Any undefined
1757           reference to "__real_symbol" will be resolved to symbol.
1758
1759           This can be used to provide a wrapper for a system function.  The
1760           wrapper function should be called "__wrap_symbol".  If it wishes to
1761           call the system function, it should call "__real_symbol".
1762
1763           Here is a trivial example:
1764
1765                   void *
1766                   __wrap_malloc (size_t c)
1767                   {
1768                     printf ("malloc called with %zu\n", c);
1769                     return __real_malloc (c);
1770                   }
1771
1772           If you link other code with this file using --wrap malloc, then all
1773           calls to "malloc" will call the function "__wrap_malloc" instead.
1774           The call to "__real_malloc" in "__wrap_malloc" will call the real
1775           "malloc" function.
1776
1777           You may wish to provide a "__real_malloc" function as well, so that
1778           links without the --wrap option will succeed.  If you do this, you
1779           should not put the definition of "__real_malloc" in the same file
1780           as "__wrap_malloc"; if you do, the assembler may resolve the call
1781           before the linker has a chance to wrap it to "malloc".
1782
1783       --eh-frame-hdr
1784       --no-eh-frame-hdr
1785           Request (--eh-frame-hdr) or suppress (--no-eh-frame-hdr) the
1786           creation of ".eh_frame_hdr" section and ELF "PT_GNU_EH_FRAME"
1787           segment header.
1788
1789       --no-ld-generated-unwind-info
1790           Request creation of ".eh_frame" unwind info for linker generated
1791           code sections like PLT.  This option is on by default if linker
1792           generated unwind info is supported.
1793
1794       --enable-new-dtags
1795       --disable-new-dtags
1796           This linker can create the new dynamic tags in ELF. But the older
1797           ELF systems may not understand them. If you specify
1798           --enable-new-dtags, the new dynamic tags will be created as needed
1799           and older dynamic tags will be omitted.  If you specify
1800           --disable-new-dtags, no new dynamic tags will be created. By
1801           default, the new dynamic tags are not created. Note that those
1802           options are only available for ELF systems.
1803
1804       --hash-size=number
1805           Set the default size of the linker's hash tables to a prime number
1806           close to number.  Increasing this value can reduce the length of
1807           time it takes the linker to perform its tasks, at the expense of
1808           increasing the linker's memory requirements.  Similarly reducing
1809           this value can reduce the memory requirements at the expense of
1810           speed.
1811
1812       --hash-style=style
1813           Set the type of linker's hash table(s).  style can be either "sysv"
1814           for classic ELF ".hash" section, "gnu" for new style GNU
1815           ".gnu.hash" section or "both" for both the classic ELF ".hash" and
1816           new style GNU ".gnu.hash" hash tables.  The default is "sysv".
1817
1818       --compress-debug-sections=none
1819       --compress-debug-sections=zlib
1820       --compress-debug-sections=zlib-gnu
1821       --compress-debug-sections=zlib-gabi
1822           On ELF platforms, these options control how DWARF debug sections
1823           are compressed using zlib.
1824
1825           --compress-debug-sections=none doesn't compress DWARF debug
1826           sections.  --compress-debug-sections=zlib-gnu compresses DWARF
1827           debug sections and renames them to begin with .zdebug instead of
1828           .debug.  --compress-debug-sections=zlib-gabi also compresses DWARF
1829           debug sections, but rather than renaming them it sets the
1830           SHF_COMPRESSED flag in the sections' headers.
1831
1832           The --compress-debug-sections=zlib option is an alias for
1833           --compress-debug-sections=zlib-gabi.
1834
1835           Note that this option overrides any compression in input debug
1836           sections, so if a binary is linked with
1837           --compress-debug-sections=none for example, then any compressed
1838           debug sections in input files will be uncompressed before they are
1839           copied into the output binary.
1840
1841           The default compression behaviour varies depending upon the target
1842           involved and the configure options used to build the toolchain.
1843           The default can be determined by examining the output from the
1844           linker's --help option.
1845
1846       --reduce-memory-overheads
1847           This option reduces memory requirements at ld runtime, at the
1848           expense of linking speed.  This was introduced to select the old
1849           O(n^2) algorithm for link map file generation, rather than the new
1850           O(n) algorithm which uses about 40% more memory for symbol storage.
1851
1852           Another effect of the switch is to set the default hash table size
1853           to 1021, which again saves memory at the cost of lengthening the
1854           linker's run time.  This is not done however if the --hash-size
1855           switch has been used.
1856
1857           The --reduce-memory-overheads switch may be also be used to enable
1858           other tradeoffs in future versions of the linker.
1859
1860       --build-id
1861       --build-id=style
1862           Request the creation of a ".note.gnu.build-id" ELF note section or
1863           a ".buildid" COFF section.  The contents of the note are unique
1864           bits identifying this linked file.  style can be "uuid" to use 128
1865           random bits, "sha1" to use a 160-bit SHA1 hash on the normative
1866           parts of the output contents, "md5" to use a 128-bit MD5 hash on
1867           the normative parts of the output contents, or "0xhexstring" to use
1868           a chosen bit string specified as an even number of hexadecimal
1869           digits ("-" and ":" characters between digit pairs are ignored).
1870           If style is omitted, "sha1" is used.
1871
1872           The "md5" and "sha1" styles produces an identifier that is always
1873           the same in an identical output file, but will be unique among all
1874           nonidentical output files.  It is not intended to be compared as a
1875           checksum for the file's contents.  A linked file may be changed
1876           later by other tools, but the build ID bit string identifying the
1877           original linked file does not change.
1878
1879           Passing "none" for style disables the setting from any "--build-id"
1880           options earlier on the command line.
1881
1882       The i386 PE linker supports the -shared option, which causes the output
1883       to be a dynamically linked library (DLL) instead of a normal
1884       executable.  You should name the output "*.dll" when you use this
1885       option.  In addition, the linker fully supports the standard "*.def"
1886       files, which may be specified on the linker command line like an object
1887       file (in fact, it should precede archives it exports symbols from, to
1888       ensure that they get linked in, just like a normal object file).
1889
1890       In addition to the options common to all targets, the i386 PE linker
1891       support additional command line options that are specific to the i386
1892       PE target.  Options that take values may be separated from their values
1893       by either a space or an equals sign.
1894
1895       --add-stdcall-alias
1896           If given, symbols with a stdcall suffix (@nn) will be exported as-
1897           is and also with the suffix stripped.  [This option is specific to
1898           the i386 PE targeted port of the linker]
1899
1900       --base-file file
1901           Use file as the name of a file in which to save the base addresses
1902           of all the relocations needed for generating DLLs with dlltool.
1903           [This is an i386 PE specific option]
1904
1905       --dll
1906           Create a DLL instead of a regular executable.  You may also use
1907           -shared or specify a "LIBRARY" in a given ".def" file.  [This
1908           option is specific to the i386 PE targeted port of the linker]
1909
1910       --enable-long-section-names
1911       --disable-long-section-names
1912           The PE variants of the COFF object format add an extension that
1913           permits the use of section names longer than eight characters, the
1914           normal limit for COFF.  By default, these names are only allowed in
1915           object files, as fully-linked executable images do not carry the
1916           COFF string table required to support the longer names.  As a GNU
1917           extension, it is possible to allow their use in executable images
1918           as well, or to (probably pointlessly!)  disallow it in object
1919           files, by using these two options.  Executable images generated
1920           with these long section names are slightly non-standard, carrying
1921           as they do a string table, and may generate confusing output when
1922           examined with non-GNU PE-aware tools, such as file viewers and
1923           dumpers.  However, GDB relies on the use of PE long section names
1924           to find Dwarf-2 debug information sections in an executable image
1925           at runtime, and so if neither option is specified on the command-
1926           line, ld will enable long section names, overriding the default and
1927           technically correct behaviour, when it finds the presence of debug
1928           information while linking an executable image and not stripping
1929           symbols.  [This option is valid for all PE targeted ports of the
1930           linker]
1931
1932       --enable-stdcall-fixup
1933       --disable-stdcall-fixup
1934           If the link finds a symbol that it cannot resolve, it will attempt
1935           to do "fuzzy linking" by looking for another defined symbol that
1936           differs only in the format of the symbol name (cdecl vs stdcall)
1937           and will resolve that symbol by linking to the match.  For example,
1938           the undefined symbol "_foo" might be linked to the function
1939           "_foo@12", or the undefined symbol "_bar@16" might be linked to the
1940           function "_bar".  When the linker does this, it prints a warning,
1941           since it normally should have failed to link, but sometimes import
1942           libraries generated from third-party dlls may need this feature to
1943           be usable.  If you specify --enable-stdcall-fixup, this feature is
1944           fully enabled and warnings are not printed.  If you specify
1945           --disable-stdcall-fixup, this feature is disabled and such
1946           mismatches are considered to be errors.  [This option is specific
1947           to the i386 PE targeted port of the linker]
1948
1949       --leading-underscore
1950       --no-leading-underscore
1951           For most targets default symbol-prefix is an underscore and is
1952           defined in target's description. By this option it is possible to
1953           disable/enable the default underscore symbol-prefix.
1954
1955       --export-all-symbols
1956           If given, all global symbols in the objects used to build a DLL
1957           will be exported by the DLL.  Note that this is the default if
1958           there otherwise wouldn't be any exported symbols.  When symbols are
1959           explicitly exported via DEF files or implicitly exported via
1960           function attributes, the default is to not export anything else
1961           unless this option is given.  Note that the symbols "DllMain@12",
1962           "DllEntryPoint@0", "DllMainCRTStartup@12", and "impure_ptr" will
1963           not be automatically exported.  Also, symbols imported from other
1964           DLLs will not be re-exported, nor will symbols specifying the DLL's
1965           internal layout such as those beginning with "_head_" or ending
1966           with "_iname".  In addition, no symbols from "libgcc", "libstd++",
1967           "libmingw32", or "crtX.o" will be exported.  Symbols whose names
1968           begin with "__rtti_" or "__builtin_" will not be exported, to help
1969           with C++ DLLs.  Finally, there is an extensive list of cygwin-
1970           private symbols that are not exported (obviously, this applies on
1971           when building DLLs for cygwin targets).  These cygwin-excludes are:
1972           "_cygwin_dll_entry@12", "_cygwin_crt0_common@8",
1973           "_cygwin_noncygwin_dll_entry@12", "_fmode", "_impure_ptr",
1974           "cygwin_attach_dll", "cygwin_premain0", "cygwin_premain1",
1975           "cygwin_premain2", "cygwin_premain3", and "environ".  [This option
1976           is specific to the i386 PE targeted port of the linker]
1977
1978       --exclude-symbols symbol,symbol,...
1979           Specifies a list of symbols which should not be automatically
1980           exported.  The symbol names may be delimited by commas or colons.
1981           [This option is specific to the i386 PE targeted port of the
1982           linker]
1983
1984       --exclude-all-symbols
1985           Specifies no symbols should be automatically exported.  [This
1986           option is specific to the i386 PE targeted port of the linker]
1987
1988       --file-alignment
1989           Specify the file alignment.  Sections in the file will always begin
1990           at file offsets which are multiples of this number.  This defaults
1991           to 512.  [This option is specific to the i386 PE targeted port of
1992           the linker]
1993
1994       --heap reserve
1995       --heap reserve,commit
1996           Specify the number of bytes of memory to reserve (and optionally
1997           commit) to be used as heap for this program.  The default is 1MB
1998           reserved, 4K committed.  [This option is specific to the i386 PE
1999           targeted port of the linker]
2000
2001       --image-base value
2002           Use value as the base address of your program or dll.  This is the
2003           lowest memory location that will be used when your program or dll
2004           is loaded.  To reduce the need to relocate and improve performance
2005           of your dlls, each should have a unique base address and not
2006           overlap any other dlls.  The default is 0x400000 for executables,
2007           and 0x10000000 for dlls.  [This option is specific to the i386 PE
2008           targeted port of the linker]
2009
2010       --kill-at
2011           If given, the stdcall suffixes (@nn) will be stripped from symbols
2012           before they are exported.  [This option is specific to the i386 PE
2013           targeted port of the linker]
2014
2015       --large-address-aware
2016           If given, the appropriate bit in the "Characteristics" field of the
2017           COFF header is set to indicate that this executable supports
2018           virtual addresses greater than 2 gigabytes.  This should be used in
2019           conjunction with the /3GB or /USERVA=value megabytes switch in the
2020           "[operating systems]" section of the BOOT.INI.  Otherwise, this bit
2021           has no effect.  [This option is specific to PE targeted ports of
2022           the linker]
2023
2024       --disable-large-address-aware
2025           Reverts the effect of a previous --large-address-aware option.
2026           This is useful if --large-address-aware is always set by the
2027           compiler driver (e.g. Cygwin gcc) and the executable does not
2028           support virtual addresses greater than 2 gigabytes.  [This option
2029           is specific to PE targeted ports of the linker]
2030
2031       --major-image-version value
2032           Sets the major number of the "image version".  Defaults to 1.
2033           [This option is specific to the i386 PE targeted port of the
2034           linker]
2035
2036       --major-os-version value
2037           Sets the major number of the "os version".  Defaults to 4.  [This
2038           option is specific to the i386 PE targeted port of the linker]
2039
2040       --major-subsystem-version value
2041           Sets the major number of the "subsystem version".  Defaults to 4.
2042           [This option is specific to the i386 PE targeted port of the
2043           linker]
2044
2045       --minor-image-version value
2046           Sets the minor number of the "image version".  Defaults to 0.
2047           [This option is specific to the i386 PE targeted port of the
2048           linker]
2049
2050       --minor-os-version value
2051           Sets the minor number of the "os version".  Defaults to 0.  [This
2052           option is specific to the i386 PE targeted port of the linker]
2053
2054       --minor-subsystem-version value
2055           Sets the minor number of the "subsystem version".  Defaults to 0.
2056           [This option is specific to the i386 PE targeted port of the
2057           linker]
2058
2059       --output-def file
2060           The linker will create the file file which will contain a DEF file
2061           corresponding to the DLL the linker is generating.  This DEF file
2062           (which should be called "*.def") may be used to create an import
2063           library with "dlltool" or may be used as a reference to
2064           automatically or implicitly exported symbols.  [This option is
2065           specific to the i386 PE targeted port of the linker]
2066
2067       --enable-auto-image-base
2068       --enable-auto-image-base=value
2069           Automatically choose the image base for DLLs, optionally starting
2070           with base value, unless one is specified using the "--image-base"
2071           argument.  By using a hash generated from the dllname to create
2072           unique image bases for each DLL, in-memory collisions and
2073           relocations which can delay program execution are avoided.  [This
2074           option is specific to the i386 PE targeted port of the linker]
2075
2076       --disable-auto-image-base
2077           Do not automatically generate a unique image base.  If there is no
2078           user-specified image base ("--image-base") then use the platform
2079           default.  [This option is specific to the i386 PE targeted port of
2080           the linker]
2081
2082       --dll-search-prefix string
2083           When linking dynamically to a dll without an import library, search
2084           for "<string><basename>.dll" in preference to "lib<basename>.dll".
2085           This behaviour allows easy distinction between DLLs built for the
2086           various "subplatforms": native, cygwin, uwin, pw, etc.  For
2087           instance, cygwin DLLs typically use "--dll-search-prefix=cyg".
2088           [This option is specific to the i386 PE targeted port of the
2089           linker]
2090
2091       --enable-auto-import
2092           Do sophisticated linking of "_symbol" to "__imp__symbol" for DATA
2093           imports from DLLs, and create the necessary thunking symbols when
2094           building the import libraries with those DATA exports. Note: Use of
2095           the 'auto-import' extension will cause the text section of the
2096           image file to be made writable. This does not conform to the PE-
2097           COFF format specification published by Microsoft.
2098
2099           Note - use of the 'auto-import' extension will also cause read only
2100           data which would normally be placed into the .rdata section to be
2101           placed into the .data section instead.  This is in order to work
2102           around a problem with consts that is described here:
2103           http://www.cygwin.com/ml/cygwin/2004-09/msg01101.html
2104
2105           Using 'auto-import' generally will 'just work' -- but sometimes you
2106           may see this message:
2107
2108           "variable '<var>' can't be auto-imported. Please read the
2109           documentation for ld's "--enable-auto-import" for details."
2110
2111           This message occurs when some (sub)expression accesses an address
2112           ultimately given by the sum of two constants (Win32 import tables
2113           only allow one).  Instances where this may occur include accesses
2114           to member fields of struct variables imported from a DLL, as well
2115           as using a constant index into an array variable imported from a
2116           DLL.  Any multiword variable (arrays, structs, long long, etc) may
2117           trigger this error condition.  However, regardless of the exact
2118           data type of the offending exported variable, ld will always detect
2119           it, issue the warning, and exit.
2120
2121           There are several ways to address this difficulty, regardless of
2122           the data type of the exported variable:
2123
2124           One way is to use --enable-runtime-pseudo-reloc switch. This leaves
2125           the task of adjusting references in your client code for runtime
2126           environment, so this method works only when runtime environment
2127           supports this feature.
2128
2129           A second solution is to force one of the 'constants' to be a
2130           variable -- that is, unknown and un-optimizable at compile time.
2131           For arrays, there are two possibilities: a) make the indexee (the
2132           array's address) a variable, or b) make the 'constant' index a
2133           variable.  Thus:
2134
2135                   extern type extern_array[];
2136                   extern_array[1] -->
2137                      { volatile type *t=extern_array; t[1] }
2138
2139           or
2140
2141                   extern type extern_array[];
2142                   extern_array[1] -->
2143                      { volatile int t=1; extern_array[t] }
2144
2145           For structs (and most other multiword data types) the only option
2146           is to make the struct itself (or the long long, or the ...)
2147           variable:
2148
2149                   extern struct s extern_struct;
2150                   extern_struct.field -->
2151                      { volatile struct s *t=&extern_struct; t->field }
2152
2153           or
2154
2155                   extern long long extern_ll;
2156                   extern_ll -->
2157                     { volatile long long * local_ll=&extern_ll; *local_ll }
2158
2159           A third method of dealing with this difficulty is to abandon
2160           'auto-import' for the offending symbol and mark it with
2161           "__declspec(dllimport)".  However, in practice that requires using
2162           compile-time #defines to indicate whether you are building a DLL,
2163           building client code that will link to the DLL, or merely
2164           building/linking to a static library.   In making the choice
2165           between the various methods of resolving the 'direct address with
2166           constant offset' problem, you should consider typical real-world
2167           usage:
2168
2169           Original:
2170
2171                   --foo.h
2172                   extern int arr[];
2173                   --foo.c
2174                   #include "foo.h"
2175                   void main(int argc, char **argv){
2176                     printf("%d\n",arr[1]);
2177                   }
2178
2179           Solution 1:
2180
2181                   --foo.h
2182                   extern int arr[];
2183                   --foo.c
2184                   #include "foo.h"
2185                   void main(int argc, char **argv){
2186                     /* This workaround is for win32 and cygwin; do not "optimize" */
2187                     volatile int *parr = arr;
2188                     printf("%d\n",parr[1]);
2189                   }
2190
2191           Solution 2:
2192
2193                   --foo.h
2194                   /* Note: auto-export is assumed (no __declspec(dllexport)) */
2195                   #if (defined(_WIN32) || defined(__CYGWIN__)) && \
2196                     !(defined(FOO_BUILD_DLL) || defined(FOO_STATIC))
2197                   #define FOO_IMPORT __declspec(dllimport)
2198                   #else
2199                   #define FOO_IMPORT
2200                   #endif
2201                   extern FOO_IMPORT int arr[];
2202                   --foo.c
2203                   #include "foo.h"
2204                   void main(int argc, char **argv){
2205                     printf("%d\n",arr[1]);
2206                   }
2207
2208           A fourth way to avoid this problem is to re-code your library to
2209           use a functional interface rather than a data interface for the
2210           offending variables (e.g. set_foo() and get_foo() accessor
2211           functions).  [This option is specific to the i386 PE targeted port
2212           of the linker]
2213
2214       --disable-auto-import
2215           Do not attempt to do sophisticated linking of "_symbol" to
2216           "__imp__symbol" for DATA imports from DLLs.  [This option is
2217           specific to the i386 PE targeted port of the linker]
2218
2219       --enable-runtime-pseudo-reloc
2220           If your code contains expressions described in --enable-auto-import
2221           section, that is, DATA imports from DLL with non-zero offset, this
2222           switch will create a vector of 'runtime pseudo relocations' which
2223           can be used by runtime environment to adjust references to such
2224           data in your client code.  [This option is specific to the i386 PE
2225           targeted port of the linker]
2226
2227       --disable-runtime-pseudo-reloc
2228           Do not create pseudo relocations for non-zero offset DATA imports
2229           from DLLs.  [This option is specific to the i386 PE targeted port
2230           of the linker]
2231
2232       --enable-extra-pe-debug
2233           Show additional debug info related to auto-import symbol thunking.
2234           [This option is specific to the i386 PE targeted port of the
2235           linker]
2236
2237       --section-alignment
2238           Sets the section alignment.  Sections in memory will always begin
2239           at addresses which are a multiple of this number.  Defaults to
2240           0x1000.  [This option is specific to the i386 PE targeted port of
2241           the linker]
2242
2243       --stack reserve
2244       --stack reserve,commit
2245           Specify the number of bytes of memory to reserve (and optionally
2246           commit) to be used as stack for this program.  The default is 2MB
2247           reserved, 4K committed.  [This option is specific to the i386 PE
2248           targeted port of the linker]
2249
2250       --subsystem which
2251       --subsystem which:major
2252       --subsystem which:major.minor
2253           Specifies the subsystem under which your program will execute.  The
2254           legal values for which are "native", "windows", "console", "posix",
2255           and "xbox".  You may optionally set the subsystem version also.
2256           Numeric values are also accepted for which.  [This option is
2257           specific to the i386 PE targeted port of the linker]
2258
2259           The following options set flags in the "DllCharacteristics" field
2260           of the PE file header: [These options are specific to PE targeted
2261           ports of the linker]
2262
2263       --high-entropy-va
2264           Image is compatible with 64-bit address space layout randomization
2265           (ASLR).
2266
2267       --dynamicbase
2268           The image base address may be relocated using address space layout
2269           randomization (ASLR).  This feature was introduced with MS Windows
2270           Vista for i386 PE targets.
2271
2272       --forceinteg
2273           Code integrity checks are enforced.
2274
2275       --nxcompat
2276           The image is compatible with the Data Execution Prevention.  This
2277           feature was introduced with MS Windows XP SP2 for i386 PE targets.
2278
2279       --no-isolation
2280           Although the image understands isolation, do not isolate the image.
2281
2282       --no-seh
2283           The image does not use SEH. No SE handler may be called from this
2284           image.
2285
2286       --no-bind
2287           Do not bind this image.
2288
2289       --wdmdriver
2290           The driver uses the MS Windows Driver Model.
2291
2292       --tsaware
2293           The image is Terminal Server aware.
2294
2295       --insert-timestamp
2296       --no-insert-timestamp
2297           Insert a real timestamp into the image.  This is the default
2298           behaviour as it matches legacy code and it means that the image
2299           will work with other, proprietary tools.  The problem with this
2300           default is that it will result in slightly different images being
2301           produced each time the same sources are linked.  The option
2302           --no-insert-timestamp can be used to insert a zero value for the
2303           timestamp, this ensuring that binaries produced from identical
2304           sources will compare identically.
2305
2306       The C6X uClinux target uses a binary format called DSBT to support
2307       shared libraries.  Each shared library in the system needs to have a
2308       unique index; all executables use an index of 0.
2309
2310       --dsbt-size size
2311           This option sets the number of entries in the DSBT of the current
2312           executable or shared library to size.  The default is to create a
2313           table with 64 entries.
2314
2315       --dsbt-index index
2316           This option sets the DSBT index of the current executable or shared
2317           library to index.  The default is 0, which is appropriate for
2318           generating executables.  If a shared library is generated with a
2319           DSBT index of 0, the "R_C6000_DSBT_INDEX" relocs are copied into
2320           the output file.
2321
2322           The --no-merge-exidx-entries switch disables the merging of
2323           adjacent exidx entries in frame unwind info.
2324
2325       The 68HC11 and 68HC12 linkers support specific options to control the
2326       memory bank switching mapping and trampoline code generation.
2327
2328       --no-trampoline
2329           This option disables the generation of trampoline. By default a
2330           trampoline is generated for each far function which is called using
2331           a "jsr" instruction (this happens when a pointer to a far function
2332           is taken).
2333
2334       --bank-window name
2335           This option indicates to the linker the name of the memory region
2336           in the MEMORY specification that describes the memory bank window.
2337           The definition of such region is then used by the linker to compute
2338           paging and addresses within the memory window.
2339
2340       The following options are supported to control handling of GOT
2341       generation when linking for 68K targets.
2342
2343       --got=type
2344           This option tells the linker which GOT generation scheme to use.
2345           type should be one of single, negative, multigot or target.  For
2346           more information refer to the Info entry for ld.
2347
2348       The following options are supported to control microMIPS instruction
2349       generation and branch relocation checks for ISA mode transitions when
2350       linking for MIPS targets.
2351
2352       --insn32
2353       --no-insn32
2354           These options control the choice of microMIPS instructions used in
2355           code generated by the linker, such as that in the PLT or lazy
2356           binding stubs, or in relaxation.  If --insn32 is used, then the
2357           linker only uses 32-bit instruction encodings.  By default or if
2358           --no-insn32 is used, all instruction encodings are used, including
2359           16-bit ones where possible.
2360
2361       --ignore-branch-isa
2362       --no-ignore-branch-isa
2363           These options control branch relocation checks for invalid ISA mode
2364           transitions.  If --ignore-branch-isa is used, then the linker
2365           accepts any branch relocations and any ISA mode transition required
2366           is lost in relocation calculation, except for some cases of "BAL"
2367           instructions which meet relaxation conditions and are converted to
2368           equivalent "JALX" instructions as the associated relocation is
2369           calculated.  By default or if --no-ignore-branch-isa is used a
2370           check is made causing the loss of an ISA mode transition to produce
2371           an error.
2372

ENVIRONMENT

2374       You can change the behaviour of ld with the environment variables
2375       "GNUTARGET", "LDEMULATION" and "COLLECT_NO_DEMANGLE".
2376
2377       "GNUTARGET" determines the input-file object format if you don't use -b
2378       (or its synonym --format).  Its value should be one of the BFD names
2379       for an input format.  If there is no "GNUTARGET" in the environment, ld
2380       uses the natural format of the target. If "GNUTARGET" is set to
2381       "default" then BFD attempts to discover the input format by examining
2382       binary input files; this method often succeeds, but there are potential
2383       ambiguities, since there is no method of ensuring that the magic number
2384       used to specify object-file formats is unique.  However, the
2385       configuration procedure for BFD on each system places the conventional
2386       format for that system first in the search-list, so ambiguities are
2387       resolved in favor of convention.
2388
2389       "LDEMULATION" determines the default emulation if you don't use the -m
2390       option.  The emulation can affect various aspects of linker behaviour,
2391       particularly the default linker script.  You can list the available
2392       emulations with the --verbose or -V options.  If the -m option is not
2393       used, and the "LDEMULATION" environment variable is not defined, the
2394       default emulation depends upon how the linker was configured.
2395
2396       Normally, the linker will default to demangling symbols.  However, if
2397       "COLLECT_NO_DEMANGLE" is set in the environment, then it will default
2398       to not demangling symbols.  This environment variable is used in a
2399       similar fashion by the "gcc" linker wrapper program.  The default may
2400       be overridden by the --demangle and --no-demangle options.
2401

SEE ALSO

2403       ar(1), nm(1), objcopy(1), objdump(1), readelf(1) and the Info entries
2404       for binutils and ld.
2405
2407       Copyright (c) 1991-2018 Free Software Foundation, Inc.
2408
2409       Permission is granted to copy, distribute and/or modify this document
2410       under the terms of the GNU Free Documentation License, Version 1.3 or
2411       any later version published by the Free Software Foundation; with no
2412       Invariant Sections, with no Front-Cover Texts, and with no Back-Cover
2413       Texts.  A copy of the license is included in the section entitled "GNU
2414       Free Documentation License".
2415
2416
2417
2418binutils-2.30                     2019-05-11                             LD(1)
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