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       -b input-format
156       --format=input-format
157           ld may be configured to support more than one kind of object file.
158           If your ld is configured this way, you can use the -b option to
159           specify the binary format for input object files that follow this
160           option on the command line.  Even when ld is configured to support
161           alternative object formats, you don't usually need to specify this,
162           as ld should be configured to expect as a default input format the
163           most usual format on each machine.  input-format is a text string,
164           the name of a particular format supported by the BFD libraries.
165           (You can list the available binary formats with objdump -i.)
166
167           You may want to use this option if you are linking files with an
168           unusual binary format.  You can also use -b to switch formats
169           explicitly (when linking object files of different formats), by
170           including -b input-format before each group of object files in a
171           particular format.
172
173           The default format is taken from the environment variable
174           "GNUTARGET".
175
176           You can also define the input format from a script, using the
177           command "TARGET";
178
179       -c MRI-commandfile
180       --mri-script=MRI-commandfile
181           For compatibility with linkers produced by MRI, ld accepts script
182           files written in an alternate, restricted command language,
183           described in the MRI Compatible Script Files section of GNU ld
184           documentation.  Introduce MRI script files with the option -c; use
185           the -T option to run linker scripts written in the general-purpose
186           ld scripting language.  If MRI-cmdfile does not exist, ld looks for
187           it in the directories specified by any -L options.
188
189       -d
190       -dc
191       -dp These three options are equivalent; multiple forms are supported
192           for compatibility with other linkers.  They assign space to common
193           symbols even if a relocatable output file is specified (with -r).
194           The script command "FORCE_COMMON_ALLOCATION" has the same effect.
195
196       --depaudit AUDITLIB
197       -P AUDITLIB
198           Adds AUDITLIB to the "DT_DEPAUDIT" entry of the dynamic section.
199           AUDITLIB is not checked for existence, nor will it use the
200           DT_SONAME specified in the library.  If specified multiple times
201           "DT_DEPAUDIT" will contain a colon separated list of audit
202           interfaces to use.  This option is only meaningful on ELF platforms
203           supporting the rtld-audit interface.  The -P option is provided for
204           Solaris compatibility.
205
206       -e entry
207       --entry=entry
208           Use entry as the explicit symbol for beginning execution of your
209           program, rather than the default entry point.  If there is no
210           symbol named entry, the linker will try to parse entry as a number,
211           and use that as the entry address (the number will be interpreted
212           in base 10; you may use a leading 0x for base 16, or a leading 0
213           for base 8).
214
215       --exclude-libs lib,lib,...
216           Specifies a list of archive libraries from which symbols should not
217           be automatically exported.  The library names may be delimited by
218           commas or colons.  Specifying "--exclude-libs ALL" excludes symbols
219           in all archive libraries from automatic export.  This option is
220           available only for the i386 PE targeted port of the linker and for
221           ELF targeted ports.  For i386 PE, symbols explicitly listed in a
222           .def file are still exported, regardless of this option.  For ELF
223           targeted ports, symbols affected by this option will be treated as
224           hidden.
225
226       --exclude-modules-for-implib module,module,...
227           Specifies a list of object files or archive members, from which
228           symbols should not be automatically exported, but which should be
229           copied wholesale into the import library being generated during the
230           link.  The module names may be delimited by commas or colons, and
231           must match exactly the filenames used by ld to open the files; for
232           archive members, this is simply the member name, but for object
233           files the name listed must include and match precisely any path
234           used to specify the input file on the linker's command-line.  This
235           option is available only for the i386 PE targeted port of the
236           linker.  Symbols explicitly listed in a .def file are still
237           exported, regardless of this option.
238
239       -E
240       --export-dynamic
241       --no-export-dynamic
242           When creating a dynamically linked executable, using the -E option
243           or the --export-dynamic option causes the linker to add all symbols
244           to the dynamic symbol table.  The dynamic symbol table is the set
245           of symbols which are visible from dynamic objects at run time.
246
247           If you do not use either of these options (or use the
248           --no-export-dynamic option to restore the default behavior), the
249           dynamic symbol table will normally contain only those symbols which
250           are referenced by some dynamic object mentioned in the link.
251
252           If you use "dlopen" to load a dynamic object which needs to refer
253           back to the symbols defined by the program, rather than some other
254           dynamic object, then you will probably need to use this option when
255           linking the program itself.
256
257           You can also use the dynamic list to control what symbols should be
258           added to the dynamic symbol table if the output format supports it.
259           See the description of --dynamic-list.
260
261           Note that this option is specific to ELF targeted ports.  PE
262           targets support a similar function to export all symbols from a DLL
263           or EXE; see the description of --export-all-symbols below.
264
265       -EB Link big-endian objects.  This affects the default output format.
266
267       -EL Link little-endian objects.  This affects the default output
268           format.
269
270       -f name
271       --auxiliary=name
272           When creating an ELF shared object, set the internal DT_AUXILIARY
273           field to the specified name.  This tells the dynamic linker that
274           the symbol table of the shared object should be used as an
275           auxiliary filter on the symbol table of the shared object name.
276
277           If you later link a program against this filter object, then, when
278           you run the program, the dynamic linker will see the DT_AUXILIARY
279           field.  If the dynamic linker resolves any symbols from the filter
280           object, it will first check whether there is a definition in the
281           shared object name.  If there is one, it will be used instead of
282           the definition in the filter object.  The shared object name need
283           not exist.  Thus the shared object name may be used to provide an
284           alternative implementation of certain functions, perhaps for
285           debugging or for machine-specific performance.
286
287           This option may be specified more than once.  The DT_AUXILIARY
288           entries will be created in the order in which they appear on the
289           command line.
290
291       -F name
292       --filter=name
293           When creating an ELF shared object, set the internal DT_FILTER
294           field to the specified name.  This tells the dynamic linker that
295           the symbol table of the shared object which is being created should
296           be used as a filter on the symbol table of the shared object name.
297
298           If you later link a program against this filter object, then, when
299           you run the program, the dynamic linker will see the DT_FILTER
300           field.  The dynamic linker will resolve symbols according to the
301           symbol table of the filter object as usual, but it will actually
302           link to the definitions found in the shared object name.  Thus the
303           filter object can be used to select a subset of the symbols
304           provided by the object name.
305
306           Some older linkers used the -F option throughout a compilation
307           toolchain for specifying object-file format for both input and
308           output object files.  The GNU linker uses other mechanisms for this
309           purpose: the -b, --format, --oformat options, the "TARGET" command
310           in linker scripts, and the "GNUTARGET" environment variable.  The
311           GNU linker will ignore the -F option when not creating an ELF
312           shared object.
313
314       -fini=name
315           When creating an ELF executable or shared object, call NAME when
316           the executable or shared object is unloaded, by setting DT_FINI to
317           the address of the function.  By default, the linker uses "_fini"
318           as the function to call.
319
320       -g  Ignored.  Provided for compatibility with other tools.
321
322       -G value
323       --gpsize=value
324           Set the maximum size of objects to be optimized using the GP
325           register to size.  This is only meaningful for object file formats
326           such as MIPS ELF that support putting large and small objects into
327           different sections.  This is ignored for other object file formats.
328
329       -h name
330       -soname=name
331           When creating an ELF shared object, set the internal DT_SONAME
332           field to the specified name.  When an executable is linked with a
333           shared object which has a DT_SONAME field, then when the executable
334           is run the dynamic linker will attempt to load the shared object
335           specified by the DT_SONAME field rather than the using the file
336           name given to the linker.
337
338       -i  Perform an incremental link (same as option -r).
339
340       -init=name
341           When creating an ELF executable or shared object, call NAME when
342           the executable or shared object is loaded, by setting DT_INIT to
343           the address of the function.  By default, the linker uses "_init"
344           as the function to call.
345
346       -l namespec
347       --library=namespec
348           Add the archive or object file specified by namespec to the list of
349           files to link.  This option may be used any number of times.  If
350           namespec is of the form :filename, ld will search the library path
351           for a file called filename, otherwise it will search the library
352           path for a file called libnamespec.a.
353
354           On systems which support shared libraries, ld may also search for
355           files other than libnamespec.a.  Specifically, on ELF and SunOS
356           systems, ld will search a directory for a library called
357           libnamespec.so before searching for one called libnamespec.a.  (By
358           convention, a ".so" extension indicates a shared library.)  Note
359           that this behavior does not apply to :filename, which always
360           specifies a file called filename.
361
362           The linker will search an archive only once, at the location where
363           it is specified on the command line.  If the archive defines a
364           symbol which was undefined in some object which appeared before the
365           archive on the command line, the linker will include the
366           appropriate file(s) from the archive.  However, an undefined symbol
367           in an object appearing later on the command line will not cause the
368           linker to search the archive again.
369
370           See the -( option for a way to force the linker to search archives
371           multiple times.
372
373           You may list the same archive multiple times on the command line.
374
375           This type of archive searching is standard for Unix linkers.
376           However, if you are using ld on AIX, note that it is different from
377           the behaviour of the AIX linker.
378
379       -L searchdir
380       --library-path=searchdir
381           Add path searchdir to the list of paths that ld will search for
382           archive libraries and ld control scripts.  You may use this option
383           any number of times.  The directories are searched in the order in
384           which they are specified on the command line.  Directories
385           specified on the command line are searched before the default
386           directories.  All -L options apply to all -l options, regardless of
387           the order in which the options appear.  -L options do not affect
388           how ld searches for a linker script unless -T option is specified.
389
390           If searchdir begins with "=" or $SYSROOT, then this prefix will be
391           replaced by the sysroot prefix, controlled by the --sysroot option,
392           or specified when the linker is configured.
393
394           The default set of paths searched (without being specified with -L)
395           depends on which emulation mode ld is using, and in some cases also
396           on how it was configured.
397
398           The paths can also be specified in a link script with the
399           "SEARCH_DIR" command.  Directories specified this way are searched
400           at the point in which the linker script appears in the command
401           line.
402
403       -m emulation
404           Emulate the emulation linker.  You can list the available
405           emulations with the --verbose or -V options.
406
407           If the -m option is not used, the emulation is taken from the
408           "LDEMULATION" environment variable, if that is defined.
409
410           Otherwise, the default emulation depends upon how the linker was
411           configured.
412
413       -M
414       --print-map
415           Print a link map to the standard output.  A link map provides
416           information about the link, including the following:
417
418           ·   Where object files are mapped into memory.
419
420           ·   How common symbols are allocated.
421
422           ·   All archive members included in the link, with a mention of the
423               symbol which caused the archive member to be brought in.
424
425           ·   The values assigned to symbols.
426
427               Note - symbols whose values are computed by an expression which
428               involves a reference to a previous value of the same symbol may
429               not have correct result displayed in the link map.  This is
430               because the linker discards intermediate results and only
431               retains the final value of an expression.  Under such
432               circumstances the linker will display the final value enclosed
433               by square brackets.  Thus for example a linker script
434               containing:
435
436                          foo = 1
437                          foo = foo * 4
438                          foo = foo + 8
439
440               will produce the following output in the link map if the -M
441               option is used:
442
443                          0x00000001                foo = 0x1
444                          [0x0000000c]                foo = (foo * 0x4)
445                          [0x0000000c]                foo = (foo + 0x8)
446
447               See Expressions for more information about expressions in
448               linker scripts.
449
450           ·   How GNU properties are merged.
451
452               When the linker merges input .note.gnu.property sections into
453               one output .note.gnu.property section, some properties are
454               removed or updated.  These actions are reported in the link
455               map.  For example:
456
457                       Removed property 0xc0000002 to merge foo.o (0x1) and bar.o (not found)
458
459               This indicates that property 0xc0000002 is removed from output
460               when merging properties in  foo.o, whose property 0xc0000002
461               value is 0x1, and bar.o, which doesn't have property
462               0xc0000002.
463
464                       Updated property 0xc0010001 (0x1) to merge foo.o (0x1) and bar.o (0x1)
465
466               This indicates that property 0xc0010001 value is updated to 0x1
467               in output when merging properties in  foo.o, whose 0xc0010001
468               property value is 0x1, and bar.o, whose 0xc0010001 property
469               value is 0x1.
470
471       --print-map-discarded
472       --no-print-map-discarded
473           Print (or do not print) the list of discarded and garbage collected
474           sections in the link map.  Enabled by default.
475
476       -n
477       --nmagic
478           Turn off page alignment of sections, and disable linking against
479           shared libraries.  If the output format supports Unix style magic
480           numbers, mark the output as "NMAGIC".
481
482       -N
483       --omagic
484           Set the text and data sections to be readable and writable.  Also,
485           do not page-align the data segment, and disable linking against
486           shared libraries.  If the output format supports Unix style magic
487           numbers, mark the output as "OMAGIC". Note: Although a writable
488           text section is allowed for PE-COFF targets, it does not conform to
489           the format specification published by Microsoft.
490
491       --no-omagic
492           This option negates most of the effects of the -N option.  It sets
493           the text section to be read-only, and forces the data segment to be
494           page-aligned.  Note - this option does not enable linking against
495           shared libraries.  Use -Bdynamic for this.
496
497       -o output
498       --output=output
499           Use output as the name for the program produced by ld; if this
500           option is not specified, the name a.out is used by default.  The
501           script command "OUTPUT" can also specify the output file name.
502
503       -O level
504           If level is a numeric values greater than zero ld optimizes the
505           output.  This might take significantly longer and therefore
506           probably should only be enabled for the final binary.  At the
507           moment this option only affects ELF shared library generation.
508           Future releases of the linker may make more use of this option.
509           Also currently there is no difference in the linker's behaviour for
510           different non-zero values of this option.  Again this may change
511           with future releases.
512
513       -plugin name
514           Involve a plugin in the linking process.  The name parameter is the
515           absolute filename of the plugin.  Usually this parameter is
516           automatically added by the complier, when using link time
517           optimization, but users can also add their own plugins if they so
518           wish.
519
520           Note that the location of the compiler originated plugins is
521           different from the place where the ar, nm and ranlib programs
522           search for their plugins.  In order for those commands to make use
523           of a compiler based plugin it must first be copied into the
524           ${libdir}/bfd-plugins directory.  All gcc based linker plugins are
525           backward compatible, so it is sufficient to just copy in the newest
526           one.
527
528       --push-state
529           The --push-state allows to preserve the current state of the flags
530           which govern the input file handling so that they can all be
531           restored with one corresponding --pop-state option.
532
533           The option which are covered are: -Bdynamic, -Bstatic, -dn, -dy,
534           -call_shared, -non_shared, -static, -N, -n, --whole-archive,
535           --no-whole-archive, -r, -Ur, --copy-dt-needed-entries,
536           --no-copy-dt-needed-entries, --as-needed, --no-as-needed, and -a.
537
538           One target for this option are specifications for pkg-config.  When
539           used with the --libs option all possibly needed libraries are
540           listed and then possibly linked with all the time.  It is better to
541           return something as follows:
542
543                   -Wl,--push-state,--as-needed -libone -libtwo -Wl,--pop-state
544
545       --pop-state
546           Undoes the effect of --push-state, restores the previous values of
547           the flags governing input file handling.
548
549       -q
550       --emit-relocs
551           Leave relocation sections and contents in fully linked executables.
552           Post link analysis and optimization tools may need this information
553           in order to perform correct modifications of executables.  This
554           results in larger executables.
555
556           This option is currently only supported on ELF platforms.
557
558       --force-dynamic
559           Force the output file to have dynamic sections.  This option is
560           specific to VxWorks targets.
561
562       -r
563       --relocatable
564           Generate relocatable output---i.e., generate an output file that
565           can in turn serve as input to ld.  This is often called partial
566           linking.  As a side effect, in environments that support standard
567           Unix magic numbers, this option also sets the output file's magic
568           number to "OMAGIC".  If this option is not specified, an absolute
569           file is produced.  When linking C++ programs, this option will not
570           resolve references to constructors; to do that, use -Ur.
571
572           When an input file does not have the same format as the output
573           file, partial linking is only supported if that input file does not
574           contain any relocations.  Different output formats can have further
575           restrictions; for example some "a.out"-based formats do not support
576           partial linking with input files in other formats at all.
577
578           This option does the same thing as -i.
579
580       -R filename
581       --just-symbols=filename
582           Read symbol names and their addresses from filename, but do not
583           relocate it or include it in the output.  This allows your output
584           file to refer symbolically to absolute locations of memory defined
585           in other programs.  You may use this option more than once.
586
587           For compatibility with other ELF linkers, if the -R option is
588           followed by a directory name, rather than a file name, it is
589           treated as the -rpath option.
590
591       -s
592       --strip-all
593           Omit all symbol information from the output file.
594
595       -S
596       --strip-debug
597           Omit debugger symbol information (but not all symbols) from the
598           output file.
599
600       --strip-discarded
601       --no-strip-discarded
602           Omit (or do not omit) global symbols defined in discarded sections.
603           Enabled by default.
604
605       -t
606       --trace
607           Print the names of the input files as ld processes them.  If -t is
608           given twice then members within archives are also printed.  -t
609           output is useful to generate a list of all the object files and
610           scripts involved in linking, for example, when packaging files for
611           a linker bug report.
612
613       -T scriptfile
614       --script=scriptfile
615           Use scriptfile as the linker script.  This script replaces ld's
616           default linker script (rather than adding to it), so commandfile
617           must specify everything necessary to describe the output file.
618           If scriptfile does not exist in the current directory, "ld" looks
619           for it in the directories specified by any preceding -L options.
620           Multiple -T options accumulate.
621
622       -dT scriptfile
623       --default-script=scriptfile
624           Use scriptfile as the default linker script.
625
626           This option is similar to the --script option except that
627           processing of the script is delayed until after the rest of the
628           command line has been processed.  This allows options placed after
629           the --default-script option on the command line to affect the
630           behaviour of the linker script, which can be important when the
631           linker command line cannot be directly controlled by the user.  (eg
632           because the command line is being constructed by another tool, such
633           as gcc).
634
635       -u symbol
636       --undefined=symbol
637           Force symbol to be entered in the output file as an undefined
638           symbol.  Doing this may, for example, trigger linking of additional
639           modules from standard libraries.  -u may be repeated with different
640           option arguments to enter additional undefined symbols.  This
641           option is equivalent to the "EXTERN" linker script command.
642
643           If this option is being used to force additional modules to be
644           pulled into the link, and if it is an error for the symbol to
645           remain undefined, then the option --require-defined should be used
646           instead.
647
648       --require-defined=symbol
649           Require that symbol is defined in the output file.  This option is
650           the same as option --undefined except that if symbol is not defined
651           in the output file then the linker will issue an error and exit.
652           The same effect can be achieved in a linker script by using
653           "EXTERN", "ASSERT" and "DEFINED" together.  This option can be used
654           multiple times to require additional symbols.
655
656       -Ur For anything other than C++ programs, this option is equivalent to
657           -r: it generates relocatable output---i.e., an output file that can
658           in turn serve as input to ld.  When linking C++ programs, -Ur does
659           resolve references to constructors, unlike -r.  It does not work to
660           use -Ur on files that were themselves linked with -Ur; once the
661           constructor table has been built, it cannot be added to.  Use -Ur
662           only for the last partial link, and -r for the others.
663
664       --orphan-handling=MODE
665           Control how orphan sections are handled.  An orphan section is one
666           not specifically mentioned in a linker script.
667
668           MODE can have any of the following values:
669
670           "place"
671               Orphan sections are placed into a suitable output section
672               following the strategy described in Orphan Sections.  The
673               option --unique also affects how sections are placed.
674
675           "discard"
676               All orphan sections are discarded, by placing them in the
677               /DISCARD/ section.
678
679           "warn"
680               The linker will place the orphan section as for "place" and
681               also issue a warning.
682
683           "error"
684               The linker will exit with an error if any orphan section is
685               found.
686
687           The default if --orphan-handling is not given is "place".
688
689       --unique[=SECTION]
690           Creates a separate output section for every input section matching
691           SECTION, or if the optional wildcard SECTION argument is missing,
692           for every orphan input section.  An orphan section is one not
693           specifically mentioned in a linker script.  You may use this option
694           multiple times on the command line;  It prevents the normal merging
695           of input sections with the same name, overriding output section
696           assignments in a linker script.
697
698       -v
699       --version
700       -V  Display the version number for ld.  The -V option also lists the
701           supported emulations.
702
703       -x
704       --discard-all
705           Delete all local symbols.
706
707       -X
708       --discard-locals
709           Delete all temporary local symbols.  (These symbols start with
710           system-specific local label prefixes, typically .L for ELF systems
711           or L for traditional a.out systems.)
712
713       -y symbol
714       --trace-symbol=symbol
715           Print the name of each linked file in which symbol appears.  This
716           option may be given any number of times.  On many systems it is
717           necessary to prepend an underscore.
718
719           This option is useful when you have an undefined symbol in your
720           link but don't know where the reference is coming from.
721
722       -Y path
723           Add path to the default library search path.  This option exists
724           for Solaris compatibility.
725
726       -z keyword
727           The recognized keywords are:
728
729           bndplt
730               Always generate BND prefix in PLT entries. Supported for
731               Linux/x86_64.
732
733           call-nop=prefix-addr
734           call-nop=suffix-nop
735           call-nop=prefix-byte
736           call-nop=suffix-byte
737               Specify the 1-byte "NOP" padding when transforming indirect
738               call to a locally defined function, foo, via its GOT slot.
739               call-nop=prefix-addr generates "0x67 call foo".
740               call-nop=suffix-nop generates "call foo 0x90".
741               call-nop=prefix-byte generates "byte call foo".
742               call-nop=suffix-byte generates "call foo byte".  Supported for
743               i386 and x86_64.
744
745           cet-report=none
746           cet-report=warning
747           cet-report=error
748               Specify how to report the missing
749               GNU_PROPERTY_X86_FEATURE_1_IBT and
750               GNU_PROPERTY_X86_FEATURE_1_SHSTK properties in input
751               .note.gnu.property section.  cet-report=none, which is the
752               default, will make the linker not report missing properties in
753               input files.  cet-report=warning will make the linker issue a
754               warning for missing properties in input files.
755               cet-report=error will make the linker issue an error for
756               missing properties in input files.  Note that ibt will turn off
757               the missing GNU_PROPERTY_X86_FEATURE_1_IBT property report and
758               shstk will turn off the missing
759               GNU_PROPERTY_X86_FEATURE_1_SHSTK property report.  Supported
760               for Linux/i386 and Linux/x86_64.
761
762           combreloc
763           nocombreloc
764               Combine multiple dynamic relocation sections and sort to
765               improve dynamic symbol lookup caching.  Do not do this if
766               nocombreloc.
767
768           common
769           nocommon
770               Generate common symbols with STT_COMMON type during a
771               relocatable link.  Use STT_OBJECT type if nocommon.
772
773           common-page-size=value
774               Set the page size most commonly used to value.  Memory image
775               layout will be optimized to minimize memory pages if the system
776               is using pages of this size.
777
778           defs
779               Report unresolved symbol references from regular object files.
780               This is done even if the linker is creating a non-symbolic
781               shared library.  This option is the inverse of -z undefs.
782
783           dynamic-undefined-weak
784           nodynamic-undefined-weak
785               Make undefined weak symbols dynamic when building a dynamic
786               object, if they are referenced from a regular object file and
787               not forced local by symbol visibility or versioning.  Do not
788               make them dynamic if nodynamic-undefined-weak.  If neither
789               option is given, a target may default to either option being in
790               force, or make some other selection of undefined weak symbols
791               dynamic.  Not all targets support these options.
792
793           execstack
794               Marks the object as requiring executable stack.
795
796           global
797               This option is only meaningful when building a shared object.
798               It makes the symbols defined by this shared object available
799               for symbol resolution of subsequently loaded libraries.
800
801           globalaudit
802               This option is only meaningful when building a dynamic
803               executable.  This option marks the executable as requiring
804               global auditing by setting the "DF_1_GLOBAUDIT" bit in the
805               "DT_FLAGS_1" dynamic tag.  Global auditing requires that any
806               auditing library defined via the --depaudit or -P command-line
807               options be run for all dynamic objects loaded by the
808               application.
809
810           ibtplt
811               Generate Intel Indirect Branch Tracking (IBT) enabled PLT
812               entries.  Supported for Linux/i386 and Linux/x86_64.
813
814           ibt Generate GNU_PROPERTY_X86_FEATURE_1_IBT in .note.gnu.property
815               section to indicate compatibility with IBT.  This also implies
816               ibtplt.  Supported for Linux/i386 and Linux/x86_64.
817
818           initfirst
819               This option is only meaningful when building a shared object.
820               It marks the object so that its runtime initialization will
821               occur before the runtime initialization of any other objects
822               brought into the process at the same time.  Similarly the
823               runtime finalization of the object will occur after the runtime
824               finalization of any other objects.
825
826           interpose
827               Specify that the dynamic loader should modify its symbol search
828               order so that symbols in this shared library interpose all
829               other shared libraries not so marked.
830
831           lazy
832               When generating an executable or shared library, mark it to
833               tell the dynamic linker to defer function call resolution to
834               the point when the function is called (lazy binding), rather
835               than at load time.  Lazy binding is the default.
836
837           loadfltr
838               Specify that the object's filters be processed immediately at
839               runtime.
840
841           max-page-size=value
842               Set the maximum memory page size supported to value.
843
844           muldefs
845               Allow multiple definitions.
846
847           nocopyreloc
848               Disable linker generated .dynbss variables used in place of
849               variables defined in shared libraries.  May result in dynamic
850               text relocations.
851
852           nodefaultlib
853               Specify that the dynamic loader search for dependencies of this
854               object should ignore any default library search paths.
855
856           nodelete
857               Specify that the object shouldn't be unloaded at runtime.
858
859           nodlopen
860               Specify that the object is not available to "dlopen".
861
862           nodump
863               Specify that the object can not be dumped by "dldump".
864
865           noexecstack
866               Marks the object as not requiring executable stack.
867
868           noextern-protected-data
869               Don't treat protected data symbols as external when building a
870               shared library.  This option overrides the linker backend
871               default.  It can be used to work around incorrect relocations
872               against protected data symbols generated by compiler.  Updates
873               on protected data symbols by another module aren't visible to
874               the resulting shared library.  Supported for i386 and x86-64.
875
876           noreloc-overflow
877               Disable relocation overflow check.  This can be used to disable
878               relocation overflow check if there will be no dynamic
879               relocation overflow at run-time.  Supported for x86_64.
880
881           now When generating an executable or shared library, mark it to
882               tell the dynamic linker to resolve all symbols when the program
883               is started, or when the shared library is loaded by dlopen,
884               instead of deferring function call resolution to the point when
885               the function is first called.
886
887           origin
888               Specify that the object requires $ORIGIN handling in paths.
889
890           relro
891           norelro
892               Create an ELF "PT_GNU_RELRO" segment header in the object.
893               This specifies a memory segment that should be made read-only
894               after relocation, if supported.  Specifying common-page-size
895               smaller than the system page size will render this protection
896               ineffective.  Don't create an ELF "PT_GNU_RELRO" segment if
897               norelro.
898
899           separate-code
900           noseparate-code
901               Create separate code "PT_LOAD" segment header in the object.
902               This specifies a memory segment that should contain only
903               instructions and must be in wholly disjoint pages from any
904               other data.  Don't create separate code "PT_LOAD" segment if
905               noseparate-code is used.
906
907           shstk
908               Generate GNU_PROPERTY_X86_FEATURE_1_SHSTK in .note.gnu.property
909               section to indicate compatibility with Intel Shadow Stack.
910               Supported for Linux/i386 and Linux/x86_64.
911
912           stack-size=value
913               Specify a stack size for an ELF "PT_GNU_STACK" segment.
914               Specifying zero will override any default non-zero sized
915               "PT_GNU_STACK" segment creation.
916
917           text
918           notext
919           textoff
920               Report an error if DT_TEXTREL is set, i.e., if the binary has
921               dynamic relocations in read-only sections.  Don't report an
922               error if notext or textoff.
923
924           undefs
925               Do not report unresolved symbol references from regular object
926               files, either when creating an executable, or when creating a
927               shared library.  This option is the inverse of -z defs.
928
929           Other keywords are ignored for Solaris compatibility.
930
931       -( archives -)
932       --start-group archives --end-group
933           The archives should be a list of archive files.  They may be either
934           explicit file names, or -l options.
935
936           The specified archives are searched repeatedly until no new
937           undefined references are created.  Normally, an archive is searched
938           only once in the order that it is specified on the command line.
939           If a symbol in that archive is needed to resolve an undefined
940           symbol referred to by an object in an archive that appears later on
941           the command line, the linker would not be able to resolve that
942           reference.  By grouping the archives, they will all be searched
943           repeatedly until all possible references are resolved.
944
945           Using this option has a significant performance cost.  It is best
946           to use it only when there are unavoidable circular references
947           between two or more archives.
948
949       --accept-unknown-input-arch
950       --no-accept-unknown-input-arch
951           Tells the linker to accept input files whose architecture cannot be
952           recognised.  The assumption is that the user knows what they are
953           doing and deliberately wants to link in these unknown input files.
954           This was the default behaviour of the linker, before release 2.14.
955           The default behaviour from release 2.14 onwards is to reject such
956           input files, and so the --accept-unknown-input-arch option has been
957           added to restore the old behaviour.
958
959       --as-needed
960       --no-as-needed
961           This option affects ELF DT_NEEDED tags for dynamic libraries
962           mentioned on the command line after the --as-needed option.
963           Normally the linker will add a DT_NEEDED tag for each dynamic
964           library mentioned on the command line, regardless of whether the
965           library is actually needed or not.  --as-needed causes a DT_NEEDED
966           tag to only be emitted for a library that at that point in the link
967           satisfies a non-weak undefined symbol reference from a regular
968           object file or, if the library is not found in the DT_NEEDED lists
969           of other needed libraries, a non-weak undefined symbol reference
970           from another needed dynamic library.  Object files or libraries
971           appearing on the command line after the library in question do not
972           affect whether the library is seen as needed.  This is similar to
973           the rules for extraction of object files from archives.
974           --no-as-needed restores the default behaviour.
975
976       --add-needed
977       --no-add-needed
978           These two options have been deprecated because of the similarity of
979           their names to the --as-needed and --no-as-needed options.  They
980           have been replaced by --copy-dt-needed-entries and
981           --no-copy-dt-needed-entries.
982
983       -assert keyword
984           This option is ignored for SunOS compatibility.
985
986       -Bdynamic
987       -dy
988       -call_shared
989           Link against dynamic libraries.  This is only meaningful on
990           platforms for which shared libraries are supported.  This option is
991           normally the default on such platforms.  The different variants of
992           this option are for compatibility with various systems.  You may
993           use this option multiple times on the command line: it affects
994           library searching for -l options which follow it.
995
996       -Bgroup
997           Set the "DF_1_GROUP" flag in the "DT_FLAGS_1" entry in the dynamic
998           section.  This causes the runtime linker to handle lookups in this
999           object and its dependencies to be performed only inside the group.
1000           --unresolved-symbols=report-all is implied.  This option is only
1001           meaningful on ELF platforms which support shared libraries.
1002
1003       -Bstatic
1004       -dn
1005       -non_shared
1006       -static
1007           Do not link against shared libraries.  This is only meaningful on
1008           platforms for which shared libraries are supported.  The different
1009           variants of this option are for compatibility with various systems.
1010           You may use this option multiple times on the command line: it
1011           affects library searching for -l options which follow it.  This
1012           option also implies --unresolved-symbols=report-all.  This option
1013           can be used with -shared.  Doing so means that a shared library is
1014           being created but that all of the library's external references
1015           must be resolved by pulling in entries from static libraries.
1016
1017       -Bsymbolic
1018           When creating a shared library, bind references to global symbols
1019           to the definition within the shared library, if any.  Normally, it
1020           is possible for a program linked against a shared library to
1021           override the definition within the shared library.  This option is
1022           only meaningful on ELF platforms which support shared libraries.
1023
1024       -Bsymbolic-functions
1025           When creating a shared library, bind references to global function
1026           symbols to the definition within the shared library, if any.  This
1027           option is only meaningful on ELF platforms which support shared
1028           libraries.
1029
1030       --dynamic-list=dynamic-list-file
1031           Specify the name of a dynamic list file to the linker.  This is
1032           typically used when creating shared libraries to specify a list of
1033           global symbols whose references shouldn't be bound to the
1034           definition within the shared library, or creating dynamically
1035           linked executables to specify a list of symbols which should be
1036           added to the symbol table in the executable.  This option is only
1037           meaningful on ELF platforms which support shared libraries.
1038
1039           The format of the dynamic list is the same as the version node
1040           without scope and node name.  See VERSION for more information.
1041
1042       --dynamic-list-data
1043           Include all global data symbols to the dynamic list.
1044
1045       --dynamic-list-cpp-new
1046           Provide the builtin dynamic list for C++ operator new and delete.
1047           It is mainly useful for building shared libstdc++.
1048
1049       --dynamic-list-cpp-typeinfo
1050           Provide the builtin dynamic list for C++ runtime type
1051           identification.
1052
1053       --check-sections
1054       --no-check-sections
1055           Asks the linker not to check section addresses after they have been
1056           assigned to see if there are any overlaps.  Normally the linker
1057           will perform this check, and if it finds any overlaps it will
1058           produce suitable error messages.  The linker does know about, and
1059           does make allowances for sections in overlays.  The default
1060           behaviour can be restored by using the command-line switch
1061           --check-sections.  Section overlap is not usually checked for
1062           relocatable links.  You can force checking in that case by using
1063           the --check-sections option.
1064
1065       --copy-dt-needed-entries
1066       --no-copy-dt-needed-entries
1067           This option affects the treatment of dynamic libraries referred to
1068           by DT_NEEDED tags inside ELF dynamic libraries mentioned on the
1069           command line.  Normally the linker won't add a DT_NEEDED tag to the
1070           output binary for each library mentioned in a DT_NEEDED tag in an
1071           input dynamic library.  With --copy-dt-needed-entries specified on
1072           the command line however any dynamic libraries that follow it will
1073           have their DT_NEEDED entries added.  The default behaviour can be
1074           restored with --no-copy-dt-needed-entries.
1075
1076           This option also has an effect on the resolution of symbols in
1077           dynamic libraries.  With --copy-dt-needed-entries dynamic libraries
1078           mentioned on the command line will be recursively searched,
1079           following their DT_NEEDED tags to other libraries, in order to
1080           resolve symbols required by the output binary.  With the default
1081           setting however the searching of dynamic libraries that follow it
1082           will stop with the dynamic library itself.  No DT_NEEDED links will
1083           be traversed to resolve symbols.
1084
1085       --cref
1086           Output a cross reference table.  If a linker map file is being
1087           generated, the cross reference table is printed to the map file.
1088           Otherwise, it is printed on the standard output.
1089
1090           The format of the table is intentionally simple, so that it may be
1091           easily processed by a script if necessary.  The symbols are printed
1092           out, sorted by name.  For each symbol, a list of file names is
1093           given.  If the symbol is defined, the first file listed is the
1094           location of the definition.  If the symbol is defined as a common
1095           value then any files where this happens appear next.  Finally any
1096           files that reference the symbol are listed.
1097
1098       --no-define-common
1099           This option inhibits the assignment of addresses to common symbols.
1100           The script command "INHIBIT_COMMON_ALLOCATION" has the same effect.
1101
1102           The --no-define-common option allows decoupling the decision to
1103           assign addresses to Common symbols from the choice of the output
1104           file type; otherwise a non-Relocatable output type forces assigning
1105           addresses to Common symbols.  Using --no-define-common allows
1106           Common symbols that are referenced from a shared library to be
1107           assigned addresses only in the main program.  This eliminates the
1108           unused duplicate space in the shared library, and also prevents any
1109           possible confusion over resolving to the wrong duplicate when there
1110           are many dynamic modules with specialized search paths for runtime
1111           symbol resolution.
1112
1113       --force-group-allocation
1114           This option causes the linker to place section group members like
1115           normal input sections, and to delete the section groups.  This is
1116           the default behaviour for a final link but this option can be used
1117           to change the behaviour of a relocatable link (-r).  The script
1118           command "FORCE_GROUP_ALLOCATION" has the same effect.
1119
1120       --defsym=symbol=expression
1121           Create a global symbol in the output file, containing the absolute
1122           address given by expression.  You may use this option as many times
1123           as necessary to define multiple symbols in the command line.  A
1124           limited form of arithmetic is supported for the expression in this
1125           context: you may give a hexadecimal constant or the name of an
1126           existing symbol, or use "+" and "-" to add or subtract hexadecimal
1127           constants or symbols.  If you need more elaborate expressions,
1128           consider using the linker command language from a script.  Note:
1129           there should be no white space between symbol, the equals sign
1130           ("="), and expression.
1131
1132       --demangle[=style]
1133       --no-demangle
1134           These options control whether to demangle symbol names in error
1135           messages and other output.  When the linker is told to demangle, it
1136           tries to present symbol names in a readable fashion: it strips
1137           leading underscores if they are used by the object file format, and
1138           converts C++ mangled symbol names into user readable names.
1139           Different compilers have different mangling styles.  The optional
1140           demangling style argument can be used to choose an appropriate
1141           demangling style for your compiler.  The linker will demangle by
1142           default unless the environment variable COLLECT_NO_DEMANGLE is set.
1143           These options may be used to override the default.
1144
1145       -Ifile
1146       --dynamic-linker=file
1147           Set the name of the dynamic linker.  This is only meaningful when
1148           generating dynamically linked ELF executables.  The default dynamic
1149           linker is normally correct; don't use this unless you know what you
1150           are doing.
1151
1152       --no-dynamic-linker
1153           When producing an executable file, omit the request for a dynamic
1154           linker to be used at load-time.  This is only meaningful for ELF
1155           executables that contain dynamic relocations, and usually requires
1156           entry point code that is capable of processing these relocations.
1157
1158       --embedded-relocs
1159           This option is similar to the --emit-relocs option except that the
1160           relocs are stored in a target-specific section.  This option is
1161           only supported by the BFIN, CR16 and M68K targets.
1162
1163       --disable-multiple-abs-defs
1164           Do not allow multiple definitions with symbols included in filename
1165           invoked by -R or --just-symbols
1166
1167       --fatal-warnings
1168       --no-fatal-warnings
1169           Treat all warnings as errors.  The default behaviour can be
1170           restored with the option --no-fatal-warnings.
1171
1172       --force-exe-suffix
1173           Make sure that an output file has a .exe suffix.
1174
1175           If a successfully built fully linked output file does not have a
1176           ".exe" or ".dll" suffix, this option forces the linker to copy the
1177           output file to one of the same name with a ".exe" suffix. This
1178           option is useful when using unmodified Unix makefiles on a
1179           Microsoft Windows host, since some versions of Windows won't run an
1180           image unless it ends in a ".exe" suffix.
1181
1182       --gc-sections
1183       --no-gc-sections
1184           Enable garbage collection of unused input sections.  It is ignored
1185           on targets that do not support this option.  The default behaviour
1186           (of not performing this garbage collection) can be restored by
1187           specifying --no-gc-sections on the command line.  Note that garbage
1188           collection for COFF and PE format targets is supported, but the
1189           implementation is currently considered to be experimental.
1190
1191           --gc-sections decides which input sections are used by examining
1192           symbols and relocations.  The section containing the entry symbol
1193           and all sections containing symbols undefined on the command-line
1194           will be kept, as will sections containing symbols referenced by
1195           dynamic objects.  Note that when building shared libraries, the
1196           linker must assume that any visible symbol is referenced.  Once
1197           this initial set of sections has been determined, the linker
1198           recursively marks as used any section referenced by their
1199           relocations.  See --entry, --undefined, and --gc-keep-exported.
1200
1201           This option can be set when doing a partial link (enabled with
1202           option -r).  In this case the root of symbols kept must be
1203           explicitly specified either by one of the options --entry,
1204           --undefined, or --gc-keep-exported or by a "ENTRY" command in the
1205           linker script.
1206
1207       --print-gc-sections
1208       --no-print-gc-sections
1209           List all sections removed by garbage collection.  The listing is
1210           printed on stderr.  This option is only effective if garbage
1211           collection has been enabled via the --gc-sections) option.  The
1212           default behaviour (of not listing the sections that are removed)
1213           can be restored by specifying --no-print-gc-sections on the command
1214           line.
1215
1216       --gc-keep-exported
1217           When --gc-sections is enabled, this option prevents garbage
1218           collection of unused input sections that contain global symbols
1219           having default or protected visibility.  This option is intended to
1220           be used for executables where unreferenced sections would otherwise
1221           be garbage collected regardless of the external visibility of
1222           contained symbols.  Note that this option has no effect when
1223           linking shared objects since it is already the default behaviour.
1224           This option is only supported for ELF format targets.
1225
1226       --print-output-format
1227           Print the name of the default output format (perhaps influenced by
1228           other command-line options).  This is the string that would appear
1229           in an "OUTPUT_FORMAT" linker script command.
1230
1231       --print-memory-usage
1232           Print used size, total size and used size of memory regions created
1233           with the MEMORY command.  This is useful on embedded targets to
1234           have a quick view of amount of free memory.  The format of the
1235           output has one headline and one line per region.  It is both human
1236           readable and easily parsable by tools.  Here is an example of an
1237           output:
1238
1239                   Memory region         Used Size  Region Size  %age Used
1240                                ROM:        256 KB         1 MB     25.00%
1241                                RAM:          32 B         2 GB      0.00%
1242
1243       --help
1244           Print a summary of the command-line options on the standard output
1245           and exit.
1246
1247       --target-help
1248           Print a summary of all target-specific options on the standard
1249           output and exit.
1250
1251       -Map=mapfile
1252           Print a link map to the file mapfile.  See the description of the
1253           -M option, above.
1254
1255       --no-keep-memory
1256           ld normally optimizes for speed over memory usage by caching the
1257           symbol tables of input files in memory.  This option tells ld to
1258           instead optimize for memory usage, by rereading the symbol tables
1259           as necessary.  This may be required if ld runs out of memory space
1260           while linking a large executable.
1261
1262       --no-undefined
1263       -z defs
1264           Report unresolved symbol references from regular object files.
1265           This is done even if the linker is creating a non-symbolic shared
1266           library.  The switch --[no-]allow-shlib-undefined controls the
1267           behaviour for reporting unresolved references found in shared
1268           libraries being linked in.
1269
1270           The effects of this option can be reverted by using "-z undefs".
1271
1272       --allow-multiple-definition
1273       -z muldefs
1274           Normally when a symbol is defined multiple times, the linker will
1275           report a fatal error. These options allow multiple definitions and
1276           the first definition will be used.
1277
1278       --allow-shlib-undefined
1279       --no-allow-shlib-undefined
1280           Allows or disallows undefined symbols in shared libraries.  This
1281           switch is similar to --no-undefined except that it determines the
1282           behaviour when the undefined symbols are in a shared library rather
1283           than a regular object file.  It does not affect how undefined
1284           symbols in regular object files are handled.
1285
1286           The default behaviour is to report errors for any undefined symbols
1287           referenced in shared libraries if the linker is being used to
1288           create an executable, but to allow them if the linker is being used
1289           to create a shared library.
1290
1291           The reasons for allowing undefined symbol references in shared
1292           libraries specified at link time are that:
1293
1294           ·   A shared library specified at link time may not be the same as
1295               the one that is available at load time, so the symbol might
1296               actually be resolvable at load time.
1297
1298           ·   There are some operating systems, eg BeOS and HPPA, where
1299               undefined symbols in shared libraries are normal.
1300
1301               The BeOS kernel for example patches shared libraries at load
1302               time to select whichever function is most appropriate for the
1303               current architecture.  This is used, for example, to
1304               dynamically select an appropriate memset function.
1305
1306       --no-undefined-version
1307           Normally when a symbol has an undefined version, the linker will
1308           ignore it. This option disallows symbols with undefined version and
1309           a fatal error will be issued instead.
1310
1311       --default-symver
1312           Create and use a default symbol version (the soname) for
1313           unversioned exported symbols.
1314
1315       --default-imported-symver
1316           Create and use a default symbol version (the soname) for
1317           unversioned imported symbols.
1318
1319       --no-warn-mismatch
1320           Normally ld will give an error if you try to link together input
1321           files that are mismatched for some reason, perhaps because they
1322           have been compiled for different processors or for different
1323           endiannesses.  This option tells ld that it should silently permit
1324           such possible errors.  This option should only be used with care,
1325           in cases when you have taken some special action that ensures that
1326           the linker errors are inappropriate.
1327
1328       --no-warn-search-mismatch
1329           Normally ld will give a warning if it finds an incompatible library
1330           during a library search.  This option silences the warning.
1331
1332       --no-whole-archive
1333           Turn off the effect of the --whole-archive option for subsequent
1334           archive files.
1335
1336       --noinhibit-exec
1337           Retain the executable output file whenever it is still usable.
1338           Normally, the linker will not produce an output file if it
1339           encounters errors during the link process; it exits without writing
1340           an output file when it issues any error whatsoever.
1341
1342       -nostdlib
1343           Only search library directories explicitly specified on the command
1344           line.  Library directories specified in linker scripts (including
1345           linker scripts specified on the command line) are ignored.
1346
1347       --oformat=output-format
1348           ld may be configured to support more than one kind of object file.
1349           If your ld is configured this way, you can use the --oformat option
1350           to specify the binary format for the output object file.  Even when
1351           ld is configured to support alternative object formats, you don't
1352           usually need to specify this, as ld should be configured to produce
1353           as a default output format the most usual format on each machine.
1354           output-format is a text string, the name of a particular format
1355           supported by the BFD libraries.  (You can list the available binary
1356           formats with objdump -i.)  The script command "OUTPUT_FORMAT" can
1357           also specify the output format, but this option overrides it.
1358
1359       --out-implib file
1360           Create an import library in file corresponding to the executable
1361           the linker is generating (eg. a DLL or ELF program).  This import
1362           library (which should be called "*.dll.a" or "*.a" for DLLs) may be
1363           used to link clients against the generated executable; this
1364           behaviour makes it possible to skip a separate import library
1365           creation step (eg. "dlltool" for DLLs).  This option is only
1366           available for the i386 PE and ELF targetted ports of the linker.
1367
1368       -pie
1369       --pic-executable
1370           Create a position independent executable.  This is currently only
1371           supported on ELF platforms.  Position independent executables are
1372           similar to shared libraries in that they are relocated by the
1373           dynamic linker to the virtual address the OS chooses for them
1374           (which can vary between invocations).  Like normal dynamically
1375           linked executables they can be executed and symbols defined in the
1376           executable cannot be overridden by shared libraries.
1377
1378       -qmagic
1379           This option is ignored for Linux compatibility.
1380
1381       -Qy This option is ignored for SVR4 compatibility.
1382
1383       --relax
1384       --no-relax
1385           An option with machine dependent effects.  This option is only
1386           supported on a few targets.
1387
1388           On some platforms the --relax option performs target-specific,
1389           global optimizations that become possible when the linker resolves
1390           addressing in the program, such as relaxing address modes,
1391           synthesizing new instructions, selecting shorter version of current
1392           instructions, and combining constant values.
1393
1394           On some platforms these link time global optimizations may make
1395           symbolic debugging of the resulting executable impossible.  This is
1396           known to be the case for the Matsushita MN10200 and MN10300 family
1397           of processors.
1398
1399           On platforms where this is not supported, --relax is accepted, but
1400           ignored.
1401
1402           On platforms where --relax is accepted the option --no-relax can be
1403           used to disable the feature.
1404
1405       --retain-symbols-file=filename
1406           Retain only the symbols listed in the file filename, discarding all
1407           others.  filename is simply a flat file, with one symbol name per
1408           line.  This option is especially useful in environments (such as
1409           VxWorks) where a large global symbol table is accumulated
1410           gradually, to conserve run-time memory.
1411
1412           --retain-symbols-file does not discard undefined symbols, or
1413           symbols needed for relocations.
1414
1415           You may only specify --retain-symbols-file once in the command
1416           line.  It overrides -s and -S.
1417
1418       -rpath=dir
1419           Add a directory to the runtime library search path.  This is used
1420           when linking an ELF executable with shared objects.  All -rpath
1421           arguments are concatenated and passed to the runtime linker, which
1422           uses them to locate shared objects at runtime.
1423
1424           The -rpath option is also used when locating shared objects which
1425           are needed by shared objects explicitly included in the link; see
1426           the description of the -rpath-link option.  Searching -rpath in
1427           this way is only supported by native linkers and cross linkers
1428           which have been configured with the --with-sysroot option.
1429
1430           If -rpath is not used when linking an ELF executable, the contents
1431           of the environment variable "LD_RUN_PATH" will be used if it is
1432           defined.
1433
1434           The -rpath option may also be used on SunOS.  By default, on SunOS,
1435           the linker will form a runtime search path out of all the -L
1436           options it is given.  If a -rpath option is used, the runtime
1437           search path will be formed exclusively using the -rpath options,
1438           ignoring the -L options.  This can be useful when using gcc, which
1439           adds many -L options which may be on NFS mounted file systems.
1440
1441           For compatibility with other ELF linkers, if the -R option is
1442           followed by a directory name, rather than a file name, it is
1443           treated as the -rpath option.
1444
1445       -rpath-link=dir
1446           When using ELF or SunOS, one shared library may require another.
1447           This happens when an "ld -shared" link includes a shared library as
1448           one of the input files.
1449
1450           When the linker encounters such a dependency when doing a non-
1451           shared, non-relocatable link, it will automatically try to locate
1452           the required shared library and include it in the link, if it is
1453           not included explicitly.  In such a case, the -rpath-link option
1454           specifies the first set of directories to search.  The -rpath-link
1455           option may specify a sequence of directory names either by
1456           specifying a list of names separated by colons, or by appearing
1457           multiple times.
1458
1459           The tokens $ORIGIN and $LIB can appear in these search directories.
1460           They will be replaced by the full path to the directory containing
1461           the program or shared object in the case of $ORIGIN and either lib
1462           - for 32-bit binaries - or lib64 - for 64-bit binaries - in the
1463           case of $LIB.
1464
1465           The alternative form of these tokens - ${ORIGIN} and ${LIB} can
1466           also be used.  The token $PLATFORM is not supported.
1467
1468           This option should be used with caution as it overrides the search
1469           path that may have been hard compiled into a shared library. In
1470           such a case it is possible to use unintentionally a different
1471           search path than the runtime linker would do.
1472
1473           The linker uses the following search paths to locate required
1474           shared libraries:
1475
1476           1.  Any directories specified by -rpath-link options.
1477
1478           2.  Any directories specified by -rpath options.  The difference
1479               between -rpath and -rpath-link is that directories specified by
1480               -rpath options are included in the executable and used at
1481               runtime, whereas the -rpath-link option is only effective at
1482               link time. Searching -rpath in this way is only supported by
1483               native linkers and cross linkers which have been configured
1484               with the --with-sysroot option.
1485
1486           3.  On an ELF system, for native linkers, if the -rpath and
1487               -rpath-link options were not used, search the contents of the
1488               environment variable "LD_RUN_PATH".
1489
1490           4.  On SunOS, if the -rpath option was not used, search any
1491               directories specified using -L options.
1492
1493           5.  For a native linker, search the contents of the environment
1494               variable "LD_LIBRARY_PATH".
1495
1496           6.  For a native ELF linker, the directories in "DT_RUNPATH" or
1497               "DT_RPATH" of a shared library are searched for shared
1498               libraries needed by it. The "DT_RPATH" entries are ignored if
1499               "DT_RUNPATH" entries exist.
1500
1501           7.  The default directories, normally /lib and /usr/lib.
1502
1503           8.  For a native linker on an ELF system, if the file
1504               /etc/ld.so.conf exists, the list of directories found in that
1505               file.
1506
1507           If the required shared library is not found, the linker will issue
1508           a warning and continue with the link.
1509
1510       -shared
1511       -Bshareable
1512           Create a shared library.  This is currently only supported on ELF,
1513           XCOFF and SunOS platforms.  On SunOS, the linker will automatically
1514           create a shared library if the -e option is not used and there are
1515           undefined symbols in the link.
1516
1517       --sort-common
1518       --sort-common=ascending
1519       --sort-common=descending
1520           This option tells ld to sort the common symbols by alignment in
1521           ascending or descending order when it places them in the
1522           appropriate output sections.  The symbol alignments considered are
1523           sixteen-byte or larger, eight-byte, four-byte, two-byte, and one-
1524           byte. This is to prevent gaps between symbols due to alignment
1525           constraints.  If no sorting order is specified, then descending
1526           order is assumed.
1527
1528       --sort-section=name
1529           This option will apply "SORT_BY_NAME" to all wildcard section
1530           patterns in the linker script.
1531
1532       --sort-section=alignment
1533           This option will apply "SORT_BY_ALIGNMENT" to all wildcard section
1534           patterns in the linker script.
1535
1536       --spare-dynamic-tags=count
1537           This option specifies the number of empty slots to leave in the
1538           .dynamic section of ELF shared objects.  Empty slots may be needed
1539           by post processing tools, such as the prelinker.  The default is 5.
1540
1541       --split-by-file[=size]
1542           Similar to --split-by-reloc but creates a new output section for
1543           each input file when size is reached.  size defaults to a size of 1
1544           if not given.
1545
1546       --split-by-reloc[=count]
1547           Tries to creates extra sections in the output file so that no
1548           single output section in the file contains more than count
1549           relocations.  This is useful when generating huge relocatable files
1550           for downloading into certain real time kernels with the COFF object
1551           file format; since COFF cannot represent more than 65535
1552           relocations in a single section.  Note that this will fail to work
1553           with object file formats which do not support arbitrary sections.
1554           The linker will not split up individual input sections for
1555           redistribution, so if a single input section contains more than
1556           count relocations one output section will contain that many
1557           relocations.  count defaults to a value of 32768.
1558
1559       --stats
1560           Compute and display statistics about the operation of the linker,
1561           such as execution time and memory usage.
1562
1563       --sysroot=directory
1564           Use directory as the location of the sysroot, overriding the
1565           configure-time default.  This option is only supported by linkers
1566           that were configured using --with-sysroot.
1567
1568       --task-link
1569           This is used by COFF/PE based targets to create a task-linked
1570           object file where all of the global symbols have been converted to
1571           statics.
1572
1573       --traditional-format
1574           For some targets, the output of ld is different in some ways from
1575           the output of some existing linker.  This switch requests ld to use
1576           the traditional format instead.
1577
1578           For example, on SunOS, ld combines duplicate entries in the symbol
1579           string table.  This can reduce the size of an output file with full
1580           debugging information by over 30 percent.  Unfortunately, the SunOS
1581           "dbx" program can not read the resulting program ("gdb" has no
1582           trouble).  The --traditional-format switch tells ld to not combine
1583           duplicate entries.
1584
1585       --section-start=sectionname=org
1586           Locate a section in the output file at the absolute address given
1587           by org.  You may use this option as many times as necessary to
1588           locate multiple sections in the command line.  org must be a single
1589           hexadecimal integer; for compatibility with other linkers, you may
1590           omit the leading 0x usually associated with hexadecimal values.
1591           Note: there should be no white space between sectionname, the
1592           equals sign ("="), and org.
1593
1594       -Tbss=org
1595       -Tdata=org
1596       -Ttext=org
1597           Same as --section-start, with ".bss", ".data" or ".text" as the
1598           sectionname.
1599
1600       -Ttext-segment=org
1601           When creating an ELF executable, it will set the address of the
1602           first byte of the text segment.
1603
1604       -Trodata-segment=org
1605           When creating an ELF executable or shared object for a target where
1606           the read-only data is in its own segment separate from the
1607           executable text, it will set the address of the first byte of the
1608           read-only data segment.
1609
1610       -Tldata-segment=org
1611           When creating an ELF executable or shared object for x86-64 medium
1612           memory model, it will set the address of the first byte of the
1613           ldata segment.
1614
1615       --unresolved-symbols=method
1616           Determine how to handle unresolved symbols.  There are four
1617           possible values for method:
1618
1619           ignore-all
1620               Do not report any unresolved symbols.
1621
1622           report-all
1623               Report all unresolved symbols.  This is the default.
1624
1625           ignore-in-object-files
1626               Report unresolved symbols that are contained in shared
1627               libraries, but ignore them if they come from regular object
1628               files.
1629
1630           ignore-in-shared-libs
1631               Report unresolved symbols that come from regular object files,
1632               but ignore them if they come from shared libraries.  This can
1633               be useful when creating a dynamic binary and it is known that
1634               all the shared libraries that it should be referencing are
1635               included on the linker's command line.
1636
1637           The behaviour for shared libraries on their own can also be
1638           controlled by the --[no-]allow-shlib-undefined option.
1639
1640           Normally the linker will generate an error message for each
1641           reported unresolved symbol but the option --warn-unresolved-symbols
1642           can change this to a warning.
1643
1644       --dll-verbose
1645       --verbose[=NUMBER]
1646           Display the version number for ld and list the linker emulations
1647           supported.  Display which input files can and cannot be opened.
1648           Display the linker script being used by the linker. If the optional
1649           NUMBER argument > 1, plugin symbol status will also be displayed.
1650
1651       --version-script=version-scriptfile
1652           Specify the name of a version script to the linker.  This is
1653           typically used when creating shared libraries to specify additional
1654           information about the version hierarchy for the library being
1655           created.  This option is only fully supported on ELF platforms
1656           which support shared libraries; see VERSION.  It is partially
1657           supported on PE platforms, which can use version scripts to filter
1658           symbol visibility in auto-export mode: any symbols marked local in
1659           the version script will not be exported.
1660
1661       --warn-common
1662           Warn when a common symbol is combined with another common symbol or
1663           with a symbol definition.  Unix linkers allow this somewhat sloppy
1664           practice, but linkers on some other operating systems do not.  This
1665           option allows you to find potential problems from combining global
1666           symbols.  Unfortunately, some C libraries use this practice, so you
1667           may get some warnings about symbols in the libraries as well as in
1668           your programs.
1669
1670           There are three kinds of global symbols, illustrated here by C
1671           examples:
1672
1673           int i = 1;
1674               A definition, which goes in the initialized data section of the
1675               output file.
1676
1677           extern int i;
1678               An undefined reference, which does not allocate space.  There
1679               must be either a definition or a common symbol for the variable
1680               somewhere.
1681
1682           int i;
1683               A common symbol.  If there are only (one or more) common
1684               symbols for a variable, it goes in the uninitialized data area
1685               of the output file.  The linker merges multiple common symbols
1686               for the same variable into a single symbol.  If they are of
1687               different sizes, it picks the largest size.  The linker turns a
1688               common symbol into a declaration, if there is a definition of
1689               the same variable.
1690
1691           The --warn-common option can produce five kinds of warnings.  Each
1692           warning consists of a pair of lines: the first describes the symbol
1693           just encountered, and the second describes the previous symbol
1694           encountered with the same name.  One or both of the two symbols
1695           will be a common symbol.
1696
1697           1.  Turning a common symbol into a reference, because there is
1698               already a definition for the symbol.
1699
1700                       <file>(<section>): warning: common of `<symbol>'
1701                          overridden by definition
1702                       <file>(<section>): warning: defined here
1703
1704           2.  Turning a common symbol into a reference, because a later
1705               definition for the symbol is encountered.  This is the same as
1706               the previous case, except that the symbols are encountered in a
1707               different order.
1708
1709                       <file>(<section>): warning: definition of `<symbol>'
1710                          overriding common
1711                       <file>(<section>): warning: common is here
1712
1713           3.  Merging a common symbol with a previous same-sized common
1714               symbol.
1715
1716                       <file>(<section>): warning: multiple common
1717                          of `<symbol>'
1718                       <file>(<section>): warning: previous common is here
1719
1720           4.  Merging a common symbol with a previous larger common symbol.
1721
1722                       <file>(<section>): warning: common of `<symbol>'
1723                          overridden by larger common
1724                       <file>(<section>): warning: larger common is here
1725
1726           5.  Merging a common symbol with a previous smaller common symbol.
1727               This is the same as the previous case, except that the symbols
1728               are encountered in a different order.
1729
1730                       <file>(<section>): warning: common of `<symbol>'
1731                          overriding smaller common
1732                       <file>(<section>): warning: smaller common is here
1733
1734       --warn-constructors
1735           Warn if any global constructors are used.  This is only useful for
1736           a few object file formats.  For formats like COFF or ELF, the
1737           linker can not detect the use of global constructors.
1738
1739       --warn-multiple-gp
1740           Warn if multiple global pointer values are required in the output
1741           file.  This is only meaningful for certain processors, such as the
1742           Alpha.  Specifically, some processors put large-valued constants in
1743           a special section.  A special register (the global pointer) points
1744           into the middle of this section, so that constants can be loaded
1745           efficiently via a base-register relative addressing mode.  Since
1746           the offset in base-register relative mode is fixed and relatively
1747           small (e.g., 16 bits), this limits the maximum size of the constant
1748           pool.  Thus, in large programs, it is often necessary to use
1749           multiple global pointer values in order to be able to address all
1750           possible constants.  This option causes a warning to be issued
1751           whenever this case occurs.
1752
1753       --warn-once
1754           Only warn once for each undefined symbol, rather than once per
1755           module which refers to it.
1756
1757       --warn-section-align
1758           Warn if the address of an output section is changed because of
1759           alignment.  Typically, the alignment will be set by an input
1760           section.  The address will only be changed if it not explicitly
1761           specified; that is, if the "SECTIONS" command does not specify a
1762           start address for the section.
1763
1764       --warn-shared-textrel
1765           Warn if the linker adds a DT_TEXTREL to a shared object.
1766
1767       --warn-alternate-em
1768           Warn if an object has alternate ELF machine code.
1769
1770       --warn-unresolved-symbols
1771           If the linker is going to report an unresolved symbol (see the
1772           option --unresolved-symbols) it will normally generate an error.
1773           This option makes it generate a warning instead.
1774
1775       --error-unresolved-symbols
1776           This restores the linker's default behaviour of generating errors
1777           when it is reporting unresolved symbols.
1778
1779       --whole-archive
1780           For each archive mentioned on the command line after the
1781           --whole-archive option, include every object file in the archive in
1782           the link, rather than searching the archive for the required object
1783           files.  This is normally used to turn an archive file into a shared
1784           library, forcing every object to be included in the resulting
1785           shared library.  This option may be used more than once.
1786
1787           Two notes when using this option from gcc: First, gcc doesn't know
1788           about this option, so you have to use -Wl,-whole-archive.  Second,
1789           don't forget to use -Wl,-no-whole-archive after your list of
1790           archives, because gcc will add its own list of archives to your
1791           link and you may not want this flag to affect those as well.
1792
1793       --wrap=symbol
1794           Use a wrapper function for symbol.  Any undefined reference to
1795           symbol will be resolved to "__wrap_symbol".  Any undefined
1796           reference to "__real_symbol" will be resolved to symbol.
1797
1798           This can be used to provide a wrapper for a system function.  The
1799           wrapper function should be called "__wrap_symbol".  If it wishes to
1800           call the system function, it should call "__real_symbol".
1801
1802           Here is a trivial example:
1803
1804                   void *
1805                   __wrap_malloc (size_t c)
1806                   {
1807                     printf ("malloc called with %zu\n", c);
1808                     return __real_malloc (c);
1809                   }
1810
1811           If you link other code with this file using --wrap malloc, then all
1812           calls to "malloc" will call the function "__wrap_malloc" instead.
1813           The call to "__real_malloc" in "__wrap_malloc" will call the real
1814           "malloc" function.
1815
1816           You may wish to provide a "__real_malloc" function as well, so that
1817           links without the --wrap option will succeed.  If you do this, you
1818           should not put the definition of "__real_malloc" in the same file
1819           as "__wrap_malloc"; if you do, the assembler may resolve the call
1820           before the linker has a chance to wrap it to "malloc".
1821
1822           Only undefined references are replaced by the linker.  So,
1823           translation unit internal references to symbol are not resolved to
1824           "__wrap_symbol".  In the next example, the call to "f" in "g" is
1825           not resolved to "__wrap_f".
1826
1827                   int
1828                   f (void)
1829                   {
1830                     return 123;
1831                   }
1832
1833                   int
1834                   g (void)
1835                   {
1836                     return f();
1837                   }
1838
1839       --eh-frame-hdr
1840       --no-eh-frame-hdr
1841           Request (--eh-frame-hdr) or suppress (--no-eh-frame-hdr) the
1842           creation of ".eh_frame_hdr" section and ELF "PT_GNU_EH_FRAME"
1843           segment header.
1844
1845       --no-ld-generated-unwind-info
1846           Request creation of ".eh_frame" unwind info for linker generated
1847           code sections like PLT.  This option is on by default if linker
1848           generated unwind info is supported.
1849
1850       --enable-new-dtags
1851       --disable-new-dtags
1852           This linker can create the new dynamic tags in ELF. But the older
1853           ELF systems may not understand them. If you specify
1854           --enable-new-dtags, the new dynamic tags will be created as needed
1855           and older dynamic tags will be omitted.  If you specify
1856           --disable-new-dtags, no new dynamic tags will be created. By
1857           default, the new dynamic tags are not created. Note that those
1858           options are only available for ELF systems.
1859
1860       --hash-size=number
1861           Set the default size of the linker's hash tables to a prime number
1862           close to number.  Increasing this value can reduce the length of
1863           time it takes the linker to perform its tasks, at the expense of
1864           increasing the linker's memory requirements.  Similarly reducing
1865           this value can reduce the memory requirements at the expense of
1866           speed.
1867
1868       --hash-style=style
1869           Set the type of linker's hash table(s).  style can be either "sysv"
1870           for classic ELF ".hash" section, "gnu" for new style GNU
1871           ".gnu.hash" section or "both" for both the classic ELF ".hash" and
1872           new style GNU ".gnu.hash" hash tables.  The default depends upon
1873           how the linker was configured, but for most Linux based systems it
1874           will be "both".
1875
1876       --compress-debug-sections=none
1877       --compress-debug-sections=zlib
1878       --compress-debug-sections=zlib-gnu
1879       --compress-debug-sections=zlib-gabi
1880           On ELF platforms, these options control how DWARF debug sections
1881           are compressed using zlib.
1882
1883           --compress-debug-sections=none doesn't compress DWARF debug
1884           sections.  --compress-debug-sections=zlib-gnu compresses DWARF
1885           debug sections and renames them to begin with .zdebug instead of
1886           .debug.  --compress-debug-sections=zlib-gabi also compresses DWARF
1887           debug sections, but rather than renaming them it sets the
1888           SHF_COMPRESSED flag in the sections' headers.
1889
1890           The --compress-debug-sections=zlib option is an alias for
1891           --compress-debug-sections=zlib-gabi.
1892
1893           Note that this option overrides any compression in input debug
1894           sections, so if a binary is linked with
1895           --compress-debug-sections=none for example, then any compressed
1896           debug sections in input files will be uncompressed before they are
1897           copied into the output binary.
1898
1899           The default compression behaviour varies depending upon the target
1900           involved and the configure options used to build the toolchain.
1901           The default can be determined by examining the output from the
1902           linker's --help option.
1903
1904       --reduce-memory-overheads
1905           This option reduces memory requirements at ld runtime, at the
1906           expense of linking speed.  This was introduced to select the old
1907           O(n^2) algorithm for link map file generation, rather than the new
1908           O(n) algorithm which uses about 40% more memory for symbol storage.
1909
1910           Another effect of the switch is to set the default hash table size
1911           to 1021, which again saves memory at the cost of lengthening the
1912           linker's run time.  This is not done however if the --hash-size
1913           switch has been used.
1914
1915           The --reduce-memory-overheads switch may be also be used to enable
1916           other tradeoffs in future versions of the linker.
1917
1918       --build-id
1919       --build-id=style
1920           Request the creation of a ".note.gnu.build-id" ELF note section or
1921           a ".buildid" COFF section.  The contents of the note are unique
1922           bits identifying this linked file.  style can be "uuid" to use 128
1923           random bits, "sha1" to use a 160-bit SHA1 hash on the normative
1924           parts of the output contents, "md5" to use a 128-bit MD5 hash on
1925           the normative parts of the output contents, or "0xhexstring" to use
1926           a chosen bit string specified as an even number of hexadecimal
1927           digits ("-" and ":" characters between digit pairs are ignored).
1928           If style is omitted, "sha1" is used.
1929
1930           The "md5" and "sha1" styles produces an identifier that is always
1931           the same in an identical output file, but will be unique among all
1932           nonidentical output files.  It is not intended to be compared as a
1933           checksum for the file's contents.  A linked file may be changed
1934           later by other tools, but the build ID bit string identifying the
1935           original linked file does not change.
1936
1937           Passing "none" for style disables the setting from any "--build-id"
1938           options earlier on the command line.
1939
1940       The i386 PE linker supports the -shared option, which causes the output
1941       to be a dynamically linked library (DLL) instead of a normal
1942       executable.  You should name the output "*.dll" when you use this
1943       option.  In addition, the linker fully supports the standard "*.def"
1944       files, which may be specified on the linker command line like an object
1945       file (in fact, it should precede archives it exports symbols from, to
1946       ensure that they get linked in, just like a normal object file).
1947
1948       In addition to the options common to all targets, the i386 PE linker
1949       support additional command-line options that are specific to the i386
1950       PE target.  Options that take values may be separated from their values
1951       by either a space or an equals sign.
1952
1953       --add-stdcall-alias
1954           If given, symbols with a stdcall suffix (@nn) will be exported as-
1955           is and also with the suffix stripped.  [This option is specific to
1956           the i386 PE targeted port of the linker]
1957
1958       --base-file file
1959           Use file as the name of a file in which to save the base addresses
1960           of all the relocations needed for generating DLLs with dlltool.
1961           [This is an i386 PE specific option]
1962
1963       --dll
1964           Create a DLL instead of a regular executable.  You may also use
1965           -shared or specify a "LIBRARY" in a given ".def" file.  [This
1966           option is specific to the i386 PE targeted port of the linker]
1967
1968       --enable-long-section-names
1969       --disable-long-section-names
1970           The PE variants of the COFF object format add an extension that
1971           permits the use of section names longer than eight characters, the
1972           normal limit for COFF.  By default, these names are only allowed in
1973           object files, as fully-linked executable images do not carry the
1974           COFF string table required to support the longer names.  As a GNU
1975           extension, it is possible to allow their use in executable images
1976           as well, or to (probably pointlessly!)  disallow it in object
1977           files, by using these two options.  Executable images generated
1978           with these long section names are slightly non-standard, carrying
1979           as they do a string table, and may generate confusing output when
1980           examined with non-GNU PE-aware tools, such as file viewers and
1981           dumpers.  However, GDB relies on the use of PE long section names
1982           to find Dwarf-2 debug information sections in an executable image
1983           at runtime, and so if neither option is specified on the command-
1984           line, ld will enable long section names, overriding the default and
1985           technically correct behaviour, when it finds the presence of debug
1986           information while linking an executable image and not stripping
1987           symbols.  [This option is valid for all PE targeted ports of the
1988           linker]
1989
1990       --enable-stdcall-fixup
1991       --disable-stdcall-fixup
1992           If the link finds a symbol that it cannot resolve, it will attempt
1993           to do "fuzzy linking" by looking for another defined symbol that
1994           differs only in the format of the symbol name (cdecl vs stdcall)
1995           and will resolve that symbol by linking to the match.  For example,
1996           the undefined symbol "_foo" might be linked to the function
1997           "_foo@12", or the undefined symbol "_bar@16" might be linked to the
1998           function "_bar".  When the linker does this, it prints a warning,
1999           since it normally should have failed to link, but sometimes import
2000           libraries generated from third-party dlls may need this feature to
2001           be usable.  If you specify --enable-stdcall-fixup, this feature is
2002           fully enabled and warnings are not printed.  If you specify
2003           --disable-stdcall-fixup, this feature is disabled and such
2004           mismatches are considered to be errors.  [This option is specific
2005           to the i386 PE targeted port of the linker]
2006
2007       --leading-underscore
2008       --no-leading-underscore
2009           For most targets default symbol-prefix is an underscore and is
2010           defined in target's description. By this option it is possible to
2011           disable/enable the default underscore symbol-prefix.
2012
2013       --export-all-symbols
2014           If given, all global symbols in the objects used to build a DLL
2015           will be exported by the DLL.  Note that this is the default if
2016           there otherwise wouldn't be any exported symbols.  When symbols are
2017           explicitly exported via DEF files or implicitly exported via
2018           function attributes, the default is to not export anything else
2019           unless this option is given.  Note that the symbols "DllMain@12",
2020           "DllEntryPoint@0", "DllMainCRTStartup@12", and "impure_ptr" will
2021           not be automatically exported.  Also, symbols imported from other
2022           DLLs will not be re-exported, nor will symbols specifying the DLL's
2023           internal layout such as those beginning with "_head_" or ending
2024           with "_iname".  In addition, no symbols from "libgcc", "libstd++",
2025           "libmingw32", or "crtX.o" will be exported.  Symbols whose names
2026           begin with "__rtti_" or "__builtin_" will not be exported, to help
2027           with C++ DLLs.  Finally, there is an extensive list of cygwin-
2028           private symbols that are not exported (obviously, this applies on
2029           when building DLLs for cygwin targets).  These cygwin-excludes are:
2030           "_cygwin_dll_entry@12", "_cygwin_crt0_common@8",
2031           "_cygwin_noncygwin_dll_entry@12", "_fmode", "_impure_ptr",
2032           "cygwin_attach_dll", "cygwin_premain0", "cygwin_premain1",
2033           "cygwin_premain2", "cygwin_premain3", and "environ".  [This option
2034           is specific to the i386 PE targeted port of the linker]
2035
2036       --exclude-symbols symbol,symbol,...
2037           Specifies a list of symbols which should not be automatically
2038           exported.  The symbol names may be delimited by commas or colons.
2039           [This option is specific to the i386 PE targeted port of the
2040           linker]
2041
2042       --exclude-all-symbols
2043           Specifies no symbols should be automatically exported.  [This
2044           option is specific to the i386 PE targeted port of the linker]
2045
2046       --file-alignment
2047           Specify the file alignment.  Sections in the file will always begin
2048           at file offsets which are multiples of this number.  This defaults
2049           to 512.  [This option is specific to the i386 PE targeted port of
2050           the linker]
2051
2052       --heap reserve
2053       --heap reserve,commit
2054           Specify the number of bytes of memory to reserve (and optionally
2055           commit) to be used as heap for this program.  The default is 1MB
2056           reserved, 4K committed.  [This option is specific to the i386 PE
2057           targeted port of the linker]
2058
2059       --image-base value
2060           Use value as the base address of your program or dll.  This is the
2061           lowest memory location that will be used when your program or dll
2062           is loaded.  To reduce the need to relocate and improve performance
2063           of your dlls, each should have a unique base address and not
2064           overlap any other dlls.  The default is 0x400000 for executables,
2065           and 0x10000000 for dlls.  [This option is specific to the i386 PE
2066           targeted port of the linker]
2067
2068       --kill-at
2069           If given, the stdcall suffixes (@nn) will be stripped from symbols
2070           before they are exported.  [This option is specific to the i386 PE
2071           targeted port of the linker]
2072
2073       --large-address-aware
2074           If given, the appropriate bit in the "Characteristics" field of the
2075           COFF header is set to indicate that this executable supports
2076           virtual addresses greater than 2 gigabytes.  This should be used in
2077           conjunction with the /3GB or /USERVA=value megabytes switch in the
2078           "[operating systems]" section of the BOOT.INI.  Otherwise, this bit
2079           has no effect.  [This option is specific to PE targeted ports of
2080           the linker]
2081
2082       --disable-large-address-aware
2083           Reverts the effect of a previous --large-address-aware option.
2084           This is useful if --large-address-aware is always set by the
2085           compiler driver (e.g. Cygwin gcc) and the executable does not
2086           support virtual addresses greater than 2 gigabytes.  [This option
2087           is specific to PE targeted ports of the linker]
2088
2089       --major-image-version value
2090           Sets the major number of the "image version".  Defaults to 1.
2091           [This option is specific to the i386 PE targeted port of the
2092           linker]
2093
2094       --major-os-version value
2095           Sets the major number of the "os version".  Defaults to 4.  [This
2096           option is specific to the i386 PE targeted port of the linker]
2097
2098       --major-subsystem-version value
2099           Sets the major number of the "subsystem version".  Defaults to 4.
2100           [This option is specific to the i386 PE targeted port of the
2101           linker]
2102
2103       --minor-image-version value
2104           Sets the minor number of the "image version".  Defaults to 0.
2105           [This option is specific to the i386 PE targeted port of the
2106           linker]
2107
2108       --minor-os-version value
2109           Sets the minor number of the "os version".  Defaults to 0.  [This
2110           option is specific to the i386 PE targeted port of the linker]
2111
2112       --minor-subsystem-version value
2113           Sets the minor number of the "subsystem version".  Defaults to 0.
2114           [This option is specific to the i386 PE targeted port of the
2115           linker]
2116
2117       --output-def file
2118           The linker will create the file file which will contain a DEF file
2119           corresponding to the DLL the linker is generating.  This DEF file
2120           (which should be called "*.def") may be used to create an import
2121           library with "dlltool" or may be used as a reference to
2122           automatically or implicitly exported symbols.  [This option is
2123           specific to the i386 PE targeted port of the linker]
2124
2125       --enable-auto-image-base
2126       --enable-auto-image-base=value
2127           Automatically choose the image base for DLLs, optionally starting
2128           with base value, unless one is specified using the "--image-base"
2129           argument.  By using a hash generated from the dllname to create
2130           unique image bases for each DLL, in-memory collisions and
2131           relocations which can delay program execution are avoided.  [This
2132           option is specific to the i386 PE targeted port of the linker]
2133
2134       --disable-auto-image-base
2135           Do not automatically generate a unique image base.  If there is no
2136           user-specified image base ("--image-base") then use the platform
2137           default.  [This option is specific to the i386 PE targeted port of
2138           the linker]
2139
2140       --dll-search-prefix string
2141           When linking dynamically to a dll without an import library, search
2142           for "<string><basename>.dll" in preference to "lib<basename>.dll".
2143           This behaviour allows easy distinction between DLLs built for the
2144           various "subplatforms": native, cygwin, uwin, pw, etc.  For
2145           instance, cygwin DLLs typically use "--dll-search-prefix=cyg".
2146           [This option is specific to the i386 PE targeted port of the
2147           linker]
2148
2149       --enable-auto-import
2150           Do sophisticated linking of "_symbol" to "__imp__symbol" for DATA
2151           imports from DLLs, thus making it possible to bypass the dllimport
2152           mechanism on the user side and to reference unmangled symbol names.
2153           [This option is specific to the i386 PE targeted port of the
2154           linker]
2155
2156           The following remarks pertain to the original implementation of the
2157           feature and are obsolete nowadays for Cygwin and MinGW targets.
2158
2159           Note: Use of the 'auto-import' extension will cause the text
2160           section of the image file to be made writable. This does not
2161           conform to the PE-COFF format specification published by Microsoft.
2162
2163           Note - use of the 'auto-import' extension will also cause read only
2164           data which would normally be placed into the .rdata section to be
2165           placed into the .data section instead.  This is in order to work
2166           around a problem with consts that is described here:
2167           http://www.cygwin.com/ml/cygwin/2004-09/msg01101.html
2168
2169           Using 'auto-import' generally will 'just work' -- but sometimes you
2170           may see this message:
2171
2172           "variable '<var>' can't be auto-imported. Please read the
2173           documentation for ld's "--enable-auto-import" for details."
2174
2175           This message occurs when some (sub)expression accesses an address
2176           ultimately given by the sum of two constants (Win32 import tables
2177           only allow one).  Instances where this may occur include accesses
2178           to member fields of struct variables imported from a DLL, as well
2179           as using a constant index into an array variable imported from a
2180           DLL.  Any multiword variable (arrays, structs, long long, etc) may
2181           trigger this error condition.  However, regardless of the exact
2182           data type of the offending exported variable, ld will always detect
2183           it, issue the warning, and exit.
2184
2185           There are several ways to address this difficulty, regardless of
2186           the data type of the exported variable:
2187
2188           One way is to use --enable-runtime-pseudo-reloc switch. This leaves
2189           the task of adjusting references in your client code for runtime
2190           environment, so this method works only when runtime environment
2191           supports this feature.
2192
2193           A second solution is to force one of the 'constants' to be a
2194           variable -- that is, unknown and un-optimizable at compile time.
2195           For arrays, there are two possibilities: a) make the indexee (the
2196           array's address) a variable, or b) make the 'constant' index a
2197           variable.  Thus:
2198
2199                   extern type extern_array[];
2200                   extern_array[1] -->
2201                      { volatile type *t=extern_array; t[1] }
2202
2203           or
2204
2205                   extern type extern_array[];
2206                   extern_array[1] -->
2207                      { volatile int t=1; extern_array[t] }
2208
2209           For structs (and most other multiword data types) the only option
2210           is to make the struct itself (or the long long, or the ...)
2211           variable:
2212
2213                   extern struct s extern_struct;
2214                   extern_struct.field -->
2215                      { volatile struct s *t=&extern_struct; t->field }
2216
2217           or
2218
2219                   extern long long extern_ll;
2220                   extern_ll -->
2221                     { volatile long long * local_ll=&extern_ll; *local_ll }
2222
2223           A third method of dealing with this difficulty is to abandon
2224           'auto-import' for the offending symbol and mark it with
2225           "__declspec(dllimport)".  However, in practice that requires using
2226           compile-time #defines to indicate whether you are building a DLL,
2227           building client code that will link to the DLL, or merely
2228           building/linking to a static library.   In making the choice
2229           between the various methods of resolving the 'direct address with
2230           constant offset' problem, you should consider typical real-world
2231           usage:
2232
2233           Original:
2234
2235                   --foo.h
2236                   extern int arr[];
2237                   --foo.c
2238                   #include "foo.h"
2239                   void main(int argc, char **argv){
2240                     printf("%d\n",arr[1]);
2241                   }
2242
2243           Solution 1:
2244
2245                   --foo.h
2246                   extern int arr[];
2247                   --foo.c
2248                   #include "foo.h"
2249                   void main(int argc, char **argv){
2250                     /* This workaround is for win32 and cygwin; do not "optimize" */
2251                     volatile int *parr = arr;
2252                     printf("%d\n",parr[1]);
2253                   }
2254
2255           Solution 2:
2256
2257                   --foo.h
2258                   /* Note: auto-export is assumed (no __declspec(dllexport)) */
2259                   #if (defined(_WIN32) || defined(__CYGWIN__)) && \
2260                     !(defined(FOO_BUILD_DLL) || defined(FOO_STATIC))
2261                   #define FOO_IMPORT __declspec(dllimport)
2262                   #else
2263                   #define FOO_IMPORT
2264                   #endif
2265                   extern FOO_IMPORT int arr[];
2266                   --foo.c
2267                   #include "foo.h"
2268                   void main(int argc, char **argv){
2269                     printf("%d\n",arr[1]);
2270                   }
2271
2272           A fourth way to avoid this problem is to re-code your library to
2273           use a functional interface rather than a data interface for the
2274           offending variables (e.g. set_foo() and get_foo() accessor
2275           functions).
2276
2277       --disable-auto-import
2278           Do not attempt to do sophisticated linking of "_symbol" to
2279           "__imp__symbol" for DATA imports from DLLs.  [This option is
2280           specific to the i386 PE targeted port of the linker]
2281
2282       --enable-runtime-pseudo-reloc
2283           If your code contains expressions described in --enable-auto-import
2284           section, that is, DATA imports from DLL with non-zero offset, this
2285           switch will create a vector of 'runtime pseudo relocations' which
2286           can be used by runtime environment to adjust references to such
2287           data in your client code.  [This option is specific to the i386 PE
2288           targeted port of the linker]
2289
2290       --disable-runtime-pseudo-reloc
2291           Do not create pseudo relocations for non-zero offset DATA imports
2292           from DLLs.  [This option is specific to the i386 PE targeted port
2293           of the linker]
2294
2295       --enable-extra-pe-debug
2296           Show additional debug info related to auto-import symbol thunking.
2297           [This option is specific to the i386 PE targeted port of the
2298           linker]
2299
2300       --section-alignment
2301           Sets the section alignment.  Sections in memory will always begin
2302           at addresses which are a multiple of this number.  Defaults to
2303           0x1000.  [This option is specific to the i386 PE targeted port of
2304           the linker]
2305
2306       --stack reserve
2307       --stack reserve,commit
2308           Specify the number of bytes of memory to reserve (and optionally
2309           commit) to be used as stack for this program.  The default is 2MB
2310           reserved, 4K committed.  [This option is specific to the i386 PE
2311           targeted port of the linker]
2312
2313       --subsystem which
2314       --subsystem which:major
2315       --subsystem which:major.minor
2316           Specifies the subsystem under which your program will execute.  The
2317           legal values for which are "native", "windows", "console", "posix",
2318           and "xbox".  You may optionally set the subsystem version also.
2319           Numeric values are also accepted for which.  [This option is
2320           specific to the i386 PE targeted port of the linker]
2321
2322           The following options set flags in the "DllCharacteristics" field
2323           of the PE file header: [These options are specific to PE targeted
2324           ports of the linker]
2325
2326       --high-entropy-va
2327           Image is compatible with 64-bit address space layout randomization
2328           (ASLR).  This option also implies --dynamicbase and
2329           --enable-reloc-section.
2330
2331       --dynamicbase
2332           The image base address may be relocated using address space layout
2333           randomization (ASLR).  This feature was introduced with MS Windows
2334           Vista for i386 PE targets.  This option also implies
2335           --enable-reloc-section.
2336
2337       --forceinteg
2338           Code integrity checks are enforced.
2339
2340       --nxcompat
2341           The image is compatible with the Data Execution Prevention.  This
2342           feature was introduced with MS Windows XP SP2 for i386 PE targets.
2343
2344       --no-isolation
2345           Although the image understands isolation, do not isolate the image.
2346
2347       --no-seh
2348           The image does not use SEH. No SE handler may be called from this
2349           image.
2350
2351       --no-bind
2352           Do not bind this image.
2353
2354       --wdmdriver
2355           The driver uses the MS Windows Driver Model.
2356
2357       --tsaware
2358           The image is Terminal Server aware.
2359
2360       --insert-timestamp
2361       --no-insert-timestamp
2362           Insert a real timestamp into the image.  This is the default
2363           behaviour as it matches legacy code and it means that the image
2364           will work with other, proprietary tools.  The problem with this
2365           default is that it will result in slightly different images being
2366           produced each time the same sources are linked.  The option
2367           --no-insert-timestamp can be used to insert a zero value for the
2368           timestamp, this ensuring that binaries produced from identical
2369           sources will compare identically.
2370
2371       --enable-reloc-section
2372           Create the base relocation table, which is necessary if the image
2373           is loaded at a different image base than specified in the PE
2374           header.
2375
2376       The C6X uClinux target uses a binary format called DSBT to support
2377       shared libraries.  Each shared library in the system needs to have a
2378       unique index; all executables use an index of 0.
2379
2380       --dsbt-size size
2381           This option sets the number of entries in the DSBT of the current
2382           executable or shared library to size.  The default is to create a
2383           table with 64 entries.
2384
2385       --dsbt-index index
2386           This option sets the DSBT index of the current executable or shared
2387           library to index.  The default is 0, which is appropriate for
2388           generating executables.  If a shared library is generated with a
2389           DSBT index of 0, the "R_C6000_DSBT_INDEX" relocs are copied into
2390           the output file.
2391
2392           The --no-merge-exidx-entries switch disables the merging of
2393           adjacent exidx entries in frame unwind info.
2394
2395       --branch-stub
2396           This option enables linker branch relaxation by inserting branch
2397           stub sections when needed to extend the range of branches.  This
2398           option is usually not required since C-SKY supports branch and call
2399           instructions that can access the full memory range and branch
2400           relaxation is normally handled by the compiler or assembler.
2401
2402       --stub-group-size=N
2403           This option allows finer control of linker branch stub creation.
2404           It sets the maximum size of a group of input sections that can be
2405           handled by one stub section.  A negative value of N locates stub
2406           sections after their branches, while a positive value allows stub
2407           sections to appear either before or after the branches.  Values of
2408           1 or -1 indicate that the linker should choose suitable defaults.
2409
2410       The 68HC11 and 68HC12 linkers support specific options to control the
2411       memory bank switching mapping and trampoline code generation.
2412
2413       --no-trampoline
2414           This option disables the generation of trampoline. By default a
2415           trampoline is generated for each far function which is called using
2416           a "jsr" instruction (this happens when a pointer to a far function
2417           is taken).
2418
2419       --bank-window name
2420           This option indicates to the linker the name of the memory region
2421           in the MEMORY specification that describes the memory bank window.
2422           The definition of such region is then used by the linker to compute
2423           paging and addresses within the memory window.
2424
2425       The following options are supported to control handling of GOT
2426       generation when linking for 68K targets.
2427
2428       --got=type
2429           This option tells the linker which GOT generation scheme to use.
2430           type should be one of single, negative, multigot or target.  For
2431           more information refer to the Info entry for ld.
2432
2433       The following options are supported to control microMIPS instruction
2434       generation and branch relocation checks for ISA mode transitions when
2435       linking for MIPS targets.
2436
2437       --insn32
2438       --no-insn32
2439           These options control the choice of microMIPS instructions used in
2440           code generated by the linker, such as that in the PLT or lazy
2441           binding stubs, or in relaxation.  If --insn32 is used, then the
2442           linker only uses 32-bit instruction encodings.  By default or if
2443           --no-insn32 is used, all instruction encodings are used, including
2444           16-bit ones where possible.
2445
2446       --ignore-branch-isa
2447       --no-ignore-branch-isa
2448           These options control branch relocation checks for invalid ISA mode
2449           transitions.  If --ignore-branch-isa is used, then the linker
2450           accepts any branch relocations and any ISA mode transition required
2451           is lost in relocation calculation, except for some cases of "BAL"
2452           instructions which meet relaxation conditions and are converted to
2453           equivalent "JALX" instructions as the associated relocation is
2454           calculated.  By default or if --no-ignore-branch-isa is used a
2455           check is made causing the loss of an ISA mode transition to produce
2456           an error.
2457
2458       --compact-branches
2459       --compact-branches
2460           These options control the generation of compact instructions by the
2461           linker in the PLT entries for MIPS R6.
2462

ENVIRONMENT

2464       You can change the behaviour of ld with the environment variables
2465       "GNUTARGET", "LDEMULATION" and "COLLECT_NO_DEMANGLE".
2466
2467       "GNUTARGET" determines the input-file object format if you don't use -b
2468       (or its synonym --format).  Its value should be one of the BFD names
2469       for an input format.  If there is no "GNUTARGET" in the environment, ld
2470       uses the natural format of the target. If "GNUTARGET" is set to
2471       "default" then BFD attempts to discover the input format by examining
2472       binary input files; this method often succeeds, but there are potential
2473       ambiguities, since there is no method of ensuring that the magic number
2474       used to specify object-file formats is unique.  However, the
2475       configuration procedure for BFD on each system places the conventional
2476       format for that system first in the search-list, so ambiguities are
2477       resolved in favor of convention.
2478
2479       "LDEMULATION" determines the default emulation if you don't use the -m
2480       option.  The emulation can affect various aspects of linker behaviour,
2481       particularly the default linker script.  You can list the available
2482       emulations with the --verbose or -V options.  If the -m option is not
2483       used, and the "LDEMULATION" environment variable is not defined, the
2484       default emulation depends upon how the linker was configured.
2485
2486       Normally, the linker will default to demangling symbols.  However, if
2487       "COLLECT_NO_DEMANGLE" is set in the environment, then it will default
2488       to not demangling symbols.  This environment variable is used in a
2489       similar fashion by the "gcc" linker wrapper program.  The default may
2490       be overridden by the --demangle and --no-demangle options.
2491

SEE ALSO

2493       ar(1), nm(1), objcopy(1), objdump(1), readelf(1) and the Info entries
2494       for binutils and ld.
2495
2497       Copyright (c) 1991-2020 Free Software Foundation, Inc.
2498
2499       Permission is granted to copy, distribute and/or modify this document
2500       under the terms of the GNU Free Documentation License, Version 1.3 or
2501       any later version published by the Free Software Foundation; with no
2502       Invariant Sections, with no Front-Cover Texts, and with no Back-Cover
2503       Texts.  A copy of the license is included in the section entitled "GNU
2504       Free Documentation License".
2505
2506
2507
2508binutils-2.34                     2020-02-01                             LD(1)
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