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       --enable-non-contiguous-regions
207           This option avoids generating an error if an input section does not
208           fit a matching output section. The linker tries to allocate the
209           input section to subseque nt matching output sections, and
210           generates an error only if no output section is large enough.  This
211           is useful when several non-contiguous memory regions are available
212           and the input section does not require a particular one.  The order
213           in which input sections are evaluated does not change, for
214           instance:
215
216                     MEMORY {
217                       MEM1 (rwx) : ORIGIN : 0x1000, LENGTH = 0x14
218                       MEM2 (rwx) : ORIGIN : 0x1000, LENGTH = 0x40
219                       MEM3 (rwx) : ORIGIN : 0x2000, LENGTH = 0x40
220                     }
221                     SECTIONS {
222                       mem1 : { *(.data.*); } > MEM1
223                       mem2 : { *(.data.*); } > MEM2
224                       mem3 : { *(.data.*); } > MEM2
225                     }
226
227                     with input sections:
228                     .data.1: size 8
229                     .data.2: size 0x10
230                     .data.3: size 4
231
232                     results in .data.1 affected to mem1, and .data.2 and .data.3
233                     affected to mem2, even though .data.3 would fit in mem3.
234
235           This option is incompatible with INSERT statements because it
236           changes the way input sections are mapped to output sections.
237
238       --enable-non-contiguous-regions-warnings
239           This option enables warnings when "--enable-non-contiguous-regions"
240           allows possibly unexpected matches in sections mapping, potentially
241           leading to silently discarding a section instead of failing because
242           it does not fit any output region.
243
244       -e entry
245       --entry=entry
246           Use entry as the explicit symbol for beginning execution of your
247           program, rather than the default entry point.  If there is no
248           symbol named entry, the linker will try to parse entry as a number,
249           and use that as the entry address (the number will be interpreted
250           in base 10; you may use a leading 0x for base 16, or a leading 0
251           for base 8).
252
253       --exclude-libs lib,lib,...
254           Specifies a list of archive libraries from which symbols should not
255           be automatically exported.  The library names may be delimited by
256           commas or colons.  Specifying "--exclude-libs ALL" excludes symbols
257           in all archive libraries from automatic export.  This option is
258           available only for the i386 PE targeted port of the linker and for
259           ELF targeted ports.  For i386 PE, symbols explicitly listed in a
260           .def file are still exported, regardless of this option.  For ELF
261           targeted ports, symbols affected by this option will be treated as
262           hidden.
263
264       --exclude-modules-for-implib module,module,...
265           Specifies a list of object files or archive members, from which
266           symbols should not be automatically exported, but which should be
267           copied wholesale into the import library being generated during the
268           link.  The module names may be delimited by commas or colons, and
269           must match exactly the filenames used by ld to open the files; for
270           archive members, this is simply the member name, but for object
271           files the name listed must include and match precisely any path
272           used to specify the input file on the linker's command-line.  This
273           option is available only for the i386 PE targeted port of the
274           linker.  Symbols explicitly listed in a .def file are still
275           exported, regardless of this option.
276
277       -E
278       --export-dynamic
279       --no-export-dynamic
280           When creating a dynamically linked executable, using the -E option
281           or the --export-dynamic option causes the linker to add all symbols
282           to the dynamic symbol table.  The dynamic symbol table is the set
283           of symbols which are visible from dynamic objects at run time.
284
285           If you do not use either of these options (or use the
286           --no-export-dynamic option to restore the default behavior), the
287           dynamic symbol table will normally contain only those symbols which
288           are referenced by some dynamic object mentioned in the link.
289
290           If you use "dlopen" to load a dynamic object which needs to refer
291           back to the symbols defined by the program, rather than some other
292           dynamic object, then you will probably need to use this option when
293           linking the program itself.
294
295           You can also use the dynamic list to control what symbols should be
296           added to the dynamic symbol table if the output format supports it.
297           See the description of --dynamic-list.
298
299           Note that this option is specific to ELF targeted ports.  PE
300           targets support a similar function to export all symbols from a DLL
301           or EXE; see the description of --export-all-symbols below.
302
303       --export-dynamic-symbol=glob
304           When creating a dynamically linked executable, symbols matching
305           glob will be added to the dynamic symbol table. When creating a
306           shared library, references to symbols matching glob will not be
307           bound to the definitions within the shared library. This option is
308           a no-op when creating a shared library and -Bsymbolic or
309           --dynamic-list are not specified. This option is only meaningful on
310           ELF platforms which support shared libraries.
311
312       --export-dynamic-symbol-list=file
313           Specify a --export-dynamic-symbol for each pattern in the file.
314           The format of the file is the same as the version node without
315           scope and node name.  See VERSION for more information.
316
317       -EB Link big-endian objects.  This affects the default output format.
318
319       -EL Link little-endian objects.  This affects the default output
320           format.
321
322       -f name
323       --auxiliary=name
324           When creating an ELF shared object, set the internal DT_AUXILIARY
325           field to the specified name.  This tells the dynamic linker that
326           the symbol table of the shared object should be used as an
327           auxiliary filter on the symbol table of the shared object name.
328
329           If you later link a program against this filter object, then, when
330           you run the program, the dynamic linker will see the DT_AUXILIARY
331           field.  If the dynamic linker resolves any symbols from the filter
332           object, it will first check whether there is a definition in the
333           shared object name.  If there is one, it will be used instead of
334           the definition in the filter object.  The shared object name need
335           not exist.  Thus the shared object name may be used to provide an
336           alternative implementation of certain functions, perhaps for
337           debugging or for machine-specific performance.
338
339           This option may be specified more than once.  The DT_AUXILIARY
340           entries will be created in the order in which they appear on the
341           command line.
342
343       -F name
344       --filter=name
345           When creating an ELF shared object, set the internal DT_FILTER
346           field to the specified name.  This tells the dynamic linker that
347           the symbol table of the shared object which is being created should
348           be used as a filter on the symbol table of the shared object name.
349
350           If you later link a program against this filter object, then, when
351           you run the program, the dynamic linker will see the DT_FILTER
352           field.  The dynamic linker will resolve symbols according to the
353           symbol table of the filter object as usual, but it will actually
354           link to the definitions found in the shared object name.  Thus the
355           filter object can be used to select a subset of the symbols
356           provided by the object name.
357
358           Some older linkers used the -F option throughout a compilation
359           toolchain for specifying object-file format for both input and
360           output object files.  The GNU linker uses other mechanisms for this
361           purpose: the -b, --format, --oformat options, the "TARGET" command
362           in linker scripts, and the "GNUTARGET" environment variable.  The
363           GNU linker will ignore the -F option when not creating an ELF
364           shared object.
365
366       -fini=name
367           When creating an ELF executable or shared object, call NAME when
368           the executable or shared object is unloaded, by setting DT_FINI to
369           the address of the function.  By default, the linker uses "_fini"
370           as the function to call.
371
372       -g  Ignored.  Provided for compatibility with other tools.
373
374       -G value
375       --gpsize=value
376           Set the maximum size of objects to be optimized using the GP
377           register to size.  This is only meaningful for object file formats
378           such as MIPS ELF that support putting large and small objects into
379           different sections.  This is ignored for other object file formats.
380
381       -h name
382       -soname=name
383           When creating an ELF shared object, set the internal DT_SONAME
384           field to the specified name.  When an executable is linked with a
385           shared object which has a DT_SONAME field, then when the executable
386           is run the dynamic linker will attempt to load the shared object
387           specified by the DT_SONAME field rather than the using the file
388           name given to the linker.
389
390       -i  Perform an incremental link (same as option -r).
391
392       -init=name
393           When creating an ELF executable or shared object, call NAME when
394           the executable or shared object is loaded, by setting DT_INIT to
395           the address of the function.  By default, the linker uses "_init"
396           as the function to call.
397
398       -l namespec
399       --library=namespec
400           Add the archive or object file specified by namespec to the list of
401           files to link.  This option may be used any number of times.  If
402           namespec is of the form :filename, ld will search the library path
403           for a file called filename, otherwise it will search the library
404           path for a file called libnamespec.a.
405
406           On systems which support shared libraries, ld may also search for
407           files other than libnamespec.a.  Specifically, on ELF and SunOS
408           systems, ld will search a directory for a library called
409           libnamespec.so before searching for one called libnamespec.a.  (By
410           convention, a ".so" extension indicates a shared library.)  Note
411           that this behavior does not apply to :filename, which always
412           specifies a file called filename.
413
414           The linker will search an archive only once, at the location where
415           it is specified on the command line.  If the archive defines a
416           symbol which was undefined in some object which appeared before the
417           archive on the command line, the linker will include the
418           appropriate file(s) from the archive.  However, an undefined symbol
419           in an object appearing later on the command line will not cause the
420           linker to search the archive again.
421
422           See the -( option for a way to force the linker to search archives
423           multiple times.
424
425           You may list the same archive multiple times on the command line.
426
427           This type of archive searching is standard for Unix linkers.
428           However, if you are using ld on AIX, note that it is different from
429           the behaviour of the AIX linker.
430
431       -L searchdir
432       --library-path=searchdir
433           Add path searchdir to the list of paths that ld will search for
434           archive libraries and ld control scripts.  You may use this option
435           any number of times.  The directories are searched in the order in
436           which they are specified on the command line.  Directories
437           specified on the command line are searched before the default
438           directories.  All -L options apply to all -l options, regardless of
439           the order in which the options appear.  -L options do not affect
440           how ld searches for a linker script unless -T option is specified.
441
442           If searchdir begins with "=" or $SYSROOT, then this prefix will be
443           replaced by the sysroot prefix, controlled by the --sysroot option,
444           or specified when the linker is configured.
445
446           The default set of paths searched (without being specified with -L)
447           depends on which emulation mode ld is using, and in some cases also
448           on how it was configured.
449
450           The paths can also be specified in a link script with the
451           "SEARCH_DIR" command.  Directories specified this way are searched
452           at the point in which the linker script appears in the command
453           line.
454
455       -m emulation
456           Emulate the emulation linker.  You can list the available
457           emulations with the --verbose or -V options.
458
459           If the -m option is not used, the emulation is taken from the
460           "LDEMULATION" environment variable, if that is defined.
461
462           Otherwise, the default emulation depends upon how the linker was
463           configured.
464
465       -M
466       --print-map
467           Print a link map to the standard output.  A link map provides
468           information about the link, including the following:
469
470           •   Where object files are mapped into memory.
471
472           •   How common symbols are allocated.
473
474           •   All archive members included in the link, with a mention of the
475               symbol which caused the archive member to be brought in.
476
477           •   The values assigned to symbols.
478
479               Note - symbols whose values are computed by an expression which
480               involves a reference to a previous value of the same symbol may
481               not have correct result displayed in the link map.  This is
482               because the linker discards intermediate results and only
483               retains the final value of an expression.  Under such
484               circumstances the linker will display the final value enclosed
485               by square brackets.  Thus for example a linker script
486               containing:
487
488                          foo = 1
489                          foo = foo * 4
490                          foo = foo + 8
491
492               will produce the following output in the link map if the -M
493               option is used:
494
495                          0x00000001                foo = 0x1
496                          [0x0000000c]                foo = (foo * 0x4)
497                          [0x0000000c]                foo = (foo + 0x8)
498
499               See Expressions for more information about expressions in
500               linker scripts.
501
502           •   How GNU properties are merged.
503
504               When the linker merges input .note.gnu.property sections into
505               one output .note.gnu.property section, some properties are
506               removed or updated.  These actions are reported in the link
507               map.  For example:
508
509                       Removed property 0xc0000002 to merge foo.o (0x1) and bar.o (not found)
510
511               This indicates that property 0xc0000002 is removed from output
512               when merging properties in  foo.o, whose property 0xc0000002
513               value is 0x1, and bar.o, which doesn't have property
514               0xc0000002.
515
516                       Updated property 0xc0010001 (0x1) to merge foo.o (0x1) and bar.o (0x1)
517
518               This indicates that property 0xc0010001 value is updated to 0x1
519               in output when merging properties in  foo.o, whose 0xc0010001
520               property value is 0x1, and bar.o, whose 0xc0010001 property
521               value is 0x1.
522
523       --print-map-discarded
524       --no-print-map-discarded
525           Print (or do not print) the list of discarded and garbage collected
526           sections in the link map.  Enabled by default.
527
528       -n
529       --nmagic
530           Turn off page alignment of sections, and disable linking against
531           shared libraries.  If the output format supports Unix style magic
532           numbers, mark the output as "NMAGIC".
533
534       -N
535       --omagic
536           Set the text and data sections to be readable and writable.  Also,
537           do not page-align the data segment, and disable linking against
538           shared libraries.  If the output format supports Unix style magic
539           numbers, mark the output as "OMAGIC". Note: Although a writable
540           text section is allowed for PE-COFF targets, it does not conform to
541           the format specification published by Microsoft.
542
543       --no-omagic
544           This option negates most of the effects of the -N option.  It sets
545           the text section to be read-only, and forces the data segment to be
546           page-aligned.  Note - this option does not enable linking against
547           shared libraries.  Use -Bdynamic for this.
548
549       -o output
550       --output=output
551           Use output as the name for the program produced by ld; if this
552           option is not specified, the name a.out is used by default.  The
553           script command "OUTPUT" can also specify the output file name.
554
555       --dependency-file=depfile
556           Write a dependency file to depfile.  This file contains a rule
557           suitable for "make" describing the output file and all the input
558           files that were read to produce it.  The output is similar to the
559           compiler's output with -M -MP.  Note that there is no option like
560           the compiler's -MM, to exclude "system files" (which is not a well-
561           specified concept in the linker, unlike "system headers" in the
562           compiler).  So the output from --dependency-file is always specific
563           to the exact state of the installation where it was produced, and
564           should not be copied into distributed makefiles without careful
565           editing.
566
567       -O level
568           If level is a numeric values greater than zero ld optimizes the
569           output.  This might take significantly longer and therefore
570           probably should only be enabled for the final binary.  At the
571           moment this option only affects ELF shared library generation.
572           Future releases of the linker may make more use of this option.
573           Also currently there is no difference in the linker's behaviour for
574           different non-zero values of this option.  Again this may change
575           with future releases.
576
577       -plugin name
578           Involve a plugin in the linking process.  The name parameter is the
579           absolute filename of the plugin.  Usually this parameter is
580           automatically added by the complier, when using link time
581           optimization, but users can also add their own plugins if they so
582           wish.
583
584           Note that the location of the compiler originated plugins is
585           different from the place where the ar, nm and ranlib programs
586           search for their plugins.  In order for those commands to make use
587           of a compiler based plugin it must first be copied into the
588           ${libdir}/bfd-plugins directory.  All gcc based linker plugins are
589           backward compatible, so it is sufficient to just copy in the newest
590           one.
591
592       --push-state
593           The --push-state allows to preserve the current state of the flags
594           which govern the input file handling so that they can all be
595           restored with one corresponding --pop-state option.
596
597           The option which are covered are: -Bdynamic, -Bstatic, -dn, -dy,
598           -call_shared, -non_shared, -static, -N, -n, --whole-archive,
599           --no-whole-archive, -r, -Ur, --copy-dt-needed-entries,
600           --no-copy-dt-needed-entries, --as-needed, --no-as-needed, and -a.
601
602           One target for this option are specifications for pkg-config.  When
603           used with the --libs option all possibly needed libraries are
604           listed and then possibly linked with all the time.  It is better to
605           return something as follows:
606
607                   -Wl,--push-state,--as-needed -libone -libtwo -Wl,--pop-state
608
609       --pop-state
610           Undoes the effect of --push-state, restores the previous values of
611           the flags governing input file handling.
612
613       -q
614       --emit-relocs
615           Leave relocation sections and contents in fully linked executables.
616           Post link analysis and optimization tools may need this information
617           in order to perform correct modifications of executables.  This
618           results in larger executables.
619
620           This option is currently only supported on ELF platforms.
621
622       --force-dynamic
623           Force the output file to have dynamic sections.  This option is
624           specific to VxWorks targets.
625
626       -r
627       --relocatable
628           Generate relocatable output---i.e., generate an output file that
629           can in turn serve as input to ld.  This is often called partial
630           linking.  As a side effect, in environments that support standard
631           Unix magic numbers, this option also sets the output file's magic
632           number to "OMAGIC".  If this option is not specified, an absolute
633           file is produced.  When linking C++ programs, this option will not
634           resolve references to constructors; to do that, use -Ur.
635
636           When an input file does not have the same format as the output
637           file, partial linking is only supported if that input file does not
638           contain any relocations.  Different output formats can have further
639           restrictions; for example some "a.out"-based formats do not support
640           partial linking with input files in other formats at all.
641
642           This option does the same thing as -i.
643
644       -R filename
645       --just-symbols=filename
646           Read symbol names and their addresses from filename, but do not
647           relocate it or include it in the output.  This allows your output
648           file to refer symbolically to absolute locations of memory defined
649           in other programs.  You may use this option more than once.
650
651           For compatibility with other ELF linkers, if the -R option is
652           followed by a directory name, rather than a file name, it is
653           treated as the -rpath option.
654
655       -s
656       --strip-all
657           Omit all symbol information from the output file.
658
659       -S
660       --strip-debug
661           Omit debugger symbol information (but not all symbols) from the
662           output file.
663
664       --strip-discarded
665       --no-strip-discarded
666           Omit (or do not omit) global symbols defined in discarded sections.
667           Enabled by default.
668
669       -t
670       --trace
671           Print the names of the input files as ld processes them.  If -t is
672           given twice then members within archives are also printed.  -t
673           output is useful to generate a list of all the object files and
674           scripts involved in linking, for example, when packaging files for
675           a linker bug report.
676
677       -T scriptfile
678       --script=scriptfile
679           Use scriptfile as the linker script.  This script replaces ld's
680           default linker script (rather than adding to it), so commandfile
681           must specify everything necessary to describe the output file.
682           If scriptfile does not exist in the current directory, "ld" looks
683           for it in the directories specified by any preceding -L options.
684           Multiple -T options accumulate.
685
686       -dT scriptfile
687       --default-script=scriptfile
688           Use scriptfile as the default linker script.
689
690           This option is similar to the --script option except that
691           processing of the script is delayed until after the rest of the
692           command line has been processed.  This allows options placed after
693           the --default-script option on the command line to affect the
694           behaviour of the linker script, which can be important when the
695           linker command line cannot be directly controlled by the user.  (eg
696           because the command line is being constructed by another tool, such
697           as gcc).
698
699       -u symbol
700       --undefined=symbol
701           Force symbol to be entered in the output file as an undefined
702           symbol.  Doing this may, for example, trigger linking of additional
703           modules from standard libraries.  -u may be repeated with different
704           option arguments to enter additional undefined symbols.  This
705           option is equivalent to the "EXTERN" linker script command.
706
707           If this option is being used to force additional modules to be
708           pulled into the link, and if it is an error for the symbol to
709           remain undefined, then the option --require-defined should be used
710           instead.
711
712       --require-defined=symbol
713           Require that symbol is defined in the output file.  This option is
714           the same as option --undefined except that if symbol is not defined
715           in the output file then the linker will issue an error and exit.
716           The same effect can be achieved in a linker script by using
717           "EXTERN", "ASSERT" and "DEFINED" together.  This option can be used
718           multiple times to require additional symbols.
719
720       -Ur For anything other than C++ programs, this option is equivalent to
721           -r: it generates relocatable output---i.e., an output file that can
722           in turn serve as input to ld.  When linking C++ programs, -Ur does
723           resolve references to constructors, unlike -r.  It does not work to
724           use -Ur on files that were themselves linked with -Ur; once the
725           constructor table has been built, it cannot be added to.  Use -Ur
726           only for the last partial link, and -r for the others.
727
728       --orphan-handling=MODE
729           Control how orphan sections are handled.  An orphan section is one
730           not specifically mentioned in a linker script.
731
732           MODE can have any of the following values:
733
734           "place"
735               Orphan sections are placed into a suitable output section
736               following the strategy described in Orphan Sections.  The
737               option --unique also affects how sections are placed.
738
739           "discard"
740               All orphan sections are discarded, by placing them in the
741               /DISCARD/ section.
742
743           "warn"
744               The linker will place the orphan section as for "place" and
745               also issue a warning.
746
747           "error"
748               The linker will exit with an error if any orphan section is
749               found.
750
751           The default if --orphan-handling is not given is "place".
752
753       --unique[=SECTION]
754           Creates a separate output section for every input section matching
755           SECTION, or if the optional wildcard SECTION argument is missing,
756           for every orphan input section.  An orphan section is one not
757           specifically mentioned in a linker script.  You may use this option
758           multiple times on the command line;  It prevents the normal merging
759           of input sections with the same name, overriding output section
760           assignments in a linker script.
761
762       -v
763       --version
764       -V  Display the version number for ld.  The -V option also lists the
765           supported emulations.
766
767       -x
768       --discard-all
769           Delete all local symbols.
770
771       -X
772       --discard-locals
773           Delete all temporary local symbols.  (These symbols start with
774           system-specific local label prefixes, typically .L for ELF systems
775           or L for traditional a.out systems.)
776
777       -y symbol
778       --trace-symbol=symbol
779           Print the name of each linked file in which symbol appears.  This
780           option may be given any number of times.  On many systems it is
781           necessary to prepend an underscore.
782
783           This option is useful when you have an undefined symbol in your
784           link but don't know where the reference is coming from.
785
786       -Y path
787           Add path to the default library search path.  This option exists
788           for Solaris compatibility.
789
790       -z keyword
791           The recognized keywords are:
792
793           bndplt
794               Always generate BND prefix in PLT entries. Supported for
795               Linux/x86_64.
796
797           call-nop=prefix-addr
798           call-nop=suffix-nop
799           call-nop=prefix-byte
800           call-nop=suffix-byte
801               Specify the 1-byte "NOP" padding when transforming indirect
802               call to a locally defined function, foo, via its GOT slot.
803               call-nop=prefix-addr generates "0x67 call foo".
804               call-nop=suffix-nop generates "call foo 0x90".
805               call-nop=prefix-byte generates "byte call foo".
806               call-nop=suffix-byte generates "call foo byte".  Supported for
807               i386 and x86_64.
808
809           cet-report=none
810           cet-report=warning
811           cet-report=error
812               Specify how to report the missing
813               GNU_PROPERTY_X86_FEATURE_1_IBT and
814               GNU_PROPERTY_X86_FEATURE_1_SHSTK properties in input
815               .note.gnu.property section.  cet-report=none, which is the
816               default, will make the linker not report missing properties in
817               input files.  cet-report=warning will make the linker issue a
818               warning for missing properties in input files.
819               cet-report=error will make the linker issue an error for
820               missing properties in input files.  Note that ibt will turn off
821               the missing GNU_PROPERTY_X86_FEATURE_1_IBT property report and
822               shstk will turn off the missing
823               GNU_PROPERTY_X86_FEATURE_1_SHSTK property report.  Supported
824               for Linux/i386 and Linux/x86_64.
825
826           combreloc
827           nocombreloc
828               Combine multiple dynamic relocation sections and sort to
829               improve dynamic symbol lookup caching.  Do not do this if
830               nocombreloc.
831
832           common
833           nocommon
834               Generate common symbols with STT_COMMON type during a
835               relocatable link.  Use STT_OBJECT type if nocommon.
836
837           common-page-size=value
838               Set the page size most commonly used to value.  Memory image
839               layout will be optimized to minimize memory pages if the system
840               is using pages of this size.
841
842           defs
843               Report unresolved symbol references from regular object files.
844               This is done even if the linker is creating a non-symbolic
845               shared library.  This option is the inverse of -z undefs.
846
847           dynamic-undefined-weak
848           nodynamic-undefined-weak
849               Make undefined weak symbols dynamic when building a dynamic
850               object, if they are referenced from a regular object file and
851               not forced local by symbol visibility or versioning.  Do not
852               make them dynamic if nodynamic-undefined-weak.  If neither
853               option is given, a target may default to either option being in
854               force, or make some other selection of undefined weak symbols
855               dynamic.  Not all targets support these options.
856
857           execstack
858               Marks the object as requiring executable stack.
859
860           global
861               This option is only meaningful when building a shared object.
862               It makes the symbols defined by this shared object available
863               for symbol resolution of subsequently loaded libraries.
864
865           globalaudit
866               This option is only meaningful when building a dynamic
867               executable.  This option marks the executable as requiring
868               global auditing by setting the "DF_1_GLOBAUDIT" bit in the
869               "DT_FLAGS_1" dynamic tag.  Global auditing requires that any
870               auditing library defined via the --depaudit or -P command-line
871               options be run for all dynamic objects loaded by the
872               application.
873
874           ibtplt
875               Generate Intel Indirect Branch Tracking (IBT) enabled PLT
876               entries.  Supported for Linux/i386 and Linux/x86_64.
877
878           ibt Generate GNU_PROPERTY_X86_FEATURE_1_IBT in .note.gnu.property
879               section to indicate compatibility with IBT.  This also implies
880               ibtplt.  Supported for Linux/i386 and Linux/x86_64.
881
882           initfirst
883               This option is only meaningful when building a shared object.
884               It marks the object so that its runtime initialization will
885               occur before the runtime initialization of any other objects
886               brought into the process at the same time.  Similarly the
887               runtime finalization of the object will occur after the runtime
888               finalization of any other objects.
889
890           interpose
891               Specify that the dynamic loader should modify its symbol search
892               order so that symbols in this shared library interpose all
893               other shared libraries not so marked.
894
895           lazy
896               When generating an executable or shared library, mark it to
897               tell the dynamic linker to defer function call resolution to
898               the point when the function is called (lazy binding), rather
899               than at load time.  Lazy binding is the default.
900
901           loadfltr
902               Specify that the object's filters be processed immediately at
903               runtime.
904
905           max-page-size=value
906               Set the maximum memory page size supported to value.
907
908           muldefs
909               Allow multiple definitions.
910
911           nocopyreloc
912               Disable linker generated .dynbss variables used in place of
913               variables defined in shared libraries.  May result in dynamic
914               text relocations.
915
916           nodefaultlib
917               Specify that the dynamic loader search for dependencies of this
918               object should ignore any default library search paths.
919
920           nodelete
921               Specify that the object shouldn't be unloaded at runtime.
922
923           nodlopen
924               Specify that the object is not available to "dlopen".
925
926           nodump
927               Specify that the object can not be dumped by "dldump".
928
929           noexecstack
930               Marks the object as not requiring executable stack.
931
932           noextern-protected-data
933               Don't treat protected data symbols as external when building a
934               shared library.  This option overrides the linker backend
935               default.  It can be used to work around incorrect relocations
936               against protected data symbols generated by compiler.  Updates
937               on protected data symbols by another module aren't visible to
938               the resulting shared library.  Supported for i386 and x86-64.
939
940           noreloc-overflow
941               Disable relocation overflow check.  This can be used to disable
942               relocation overflow check if there will be no dynamic
943               relocation overflow at run-time.  Supported for x86_64.
944
945           now When generating an executable or shared library, mark it to
946               tell the dynamic linker to resolve all symbols when the program
947               is started, or when the shared library is loaded by dlopen,
948               instead of deferring function call resolution to the point when
949               the function is first called.
950
951           origin
952               Specify that the object requires $ORIGIN handling in paths.
953
954           relro
955           norelro
956               Create an ELF "PT_GNU_RELRO" segment header in the object.
957               This specifies a memory segment that should be made read-only
958               after relocation, if supported.  Specifying common-page-size
959               smaller than the system page size will render this protection
960               ineffective.  Don't create an ELF "PT_GNU_RELRO" segment if
961               norelro.
962
963           separate-code
964           noseparate-code
965               Create separate code "PT_LOAD" segment header in the object.
966               This specifies a memory segment that should contain only
967               instructions and must be in wholly disjoint pages from any
968               other data.  Don't create separate code "PT_LOAD" segment if
969               noseparate-code is used.
970
971           shstk
972               Generate GNU_PROPERTY_X86_FEATURE_1_SHSTK in .note.gnu.property
973               section to indicate compatibility with Intel Shadow Stack.
974               Supported for Linux/i386 and Linux/x86_64.
975
976           stack-size=value
977               Specify a stack size for an ELF "PT_GNU_STACK" segment.
978               Specifying zero will override any default non-zero sized
979               "PT_GNU_STACK" segment creation.
980
981           start-stop-visibility=value
982               Specify the ELF symbol visibility for synthesized
983               "__start_SECNAME" and "__stop_SECNAME" symbols.  value must be
984               exactly default, internal, hidden, or protected.  If no -z
985               start-stop-visibility option is given, protected is used for
986               compatibility with historical practice.  However, it's highly
987               recommended to use -z start-stop-visibility=hidden in new
988               programs and shared libraries so that these symbols are not
989               exported between shared objects, which is not usually what's
990               intended.
991
992           text
993           notext
994           textoff
995               Report an error if DT_TEXTREL is set, i.e., if the position-
996               independent or shared object has dynamic relocations in read-
997               only sections.  Don't report an error if notext or textoff.
998
999           undefs
1000               Do not report unresolved symbol references from regular object
1001               files, either when creating an executable, or when creating a
1002               shared library.  This option is the inverse of -z defs.
1003
1004           Other keywords are ignored for Solaris compatibility.
1005
1006       -( archives -)
1007       --start-group archives --end-group
1008           The archives should be a list of archive files.  They may be either
1009           explicit file names, or -l options.
1010
1011           The specified archives are searched repeatedly until no new
1012           undefined references are created.  Normally, an archive is searched
1013           only once in the order that it is specified on the command line.
1014           If a symbol in that archive is needed to resolve an undefined
1015           symbol referred to by an object in an archive that appears later on
1016           the command line, the linker would not be able to resolve that
1017           reference.  By grouping the archives, they will all be searched
1018           repeatedly until all possible references are resolved.
1019
1020           Using this option has a significant performance cost.  It is best
1021           to use it only when there are unavoidable circular references
1022           between two or more archives.
1023
1024       --accept-unknown-input-arch
1025       --no-accept-unknown-input-arch
1026           Tells the linker to accept input files whose architecture cannot be
1027           recognised.  The assumption is that the user knows what they are
1028           doing and deliberately wants to link in these unknown input files.
1029           This was the default behaviour of the linker, before release 2.14.
1030           The default behaviour from release 2.14 onwards is to reject such
1031           input files, and so the --accept-unknown-input-arch option has been
1032           added to restore the old behaviour.
1033
1034       --as-needed
1035       --no-as-needed
1036           This option affects ELF DT_NEEDED tags for dynamic libraries
1037           mentioned on the command line after the --as-needed option.
1038           Normally the linker will add a DT_NEEDED tag for each dynamic
1039           library mentioned on the command line, regardless of whether the
1040           library is actually needed or not.  --as-needed causes a DT_NEEDED
1041           tag to only be emitted for a library that at that point in the link
1042           satisfies a non-weak undefined symbol reference from a regular
1043           object file or, if the library is not found in the DT_NEEDED lists
1044           of other needed libraries, a non-weak undefined symbol reference
1045           from another needed dynamic library.  Object files or libraries
1046           appearing on the command line after the library in question do not
1047           affect whether the library is seen as needed.  This is similar to
1048           the rules for extraction of object files from archives.
1049           --no-as-needed restores the default behaviour.
1050
1051       --add-needed
1052       --no-add-needed
1053           These two options have been deprecated because of the similarity of
1054           their names to the --as-needed and --no-as-needed options.  They
1055           have been replaced by --copy-dt-needed-entries and
1056           --no-copy-dt-needed-entries.
1057
1058       -assert keyword
1059           This option is ignored for SunOS compatibility.
1060
1061       -Bdynamic
1062       -dy
1063       -call_shared
1064           Link against dynamic libraries.  This is only meaningful on
1065           platforms for which shared libraries are supported.  This option is
1066           normally the default on such platforms.  The different variants of
1067           this option are for compatibility with various systems.  You may
1068           use this option multiple times on the command line: it affects
1069           library searching for -l options which follow it.
1070
1071       -Bgroup
1072           Set the "DF_1_GROUP" flag in the "DT_FLAGS_1" entry in the dynamic
1073           section.  This causes the runtime linker to handle lookups in this
1074           object and its dependencies to be performed only inside the group.
1075           --unresolved-symbols=report-all is implied.  This option is only
1076           meaningful on ELF platforms which support shared libraries.
1077
1078       -Bstatic
1079       -dn
1080       -non_shared
1081       -static
1082           Do not link against shared libraries.  This is only meaningful on
1083           platforms for which shared libraries are supported.  The different
1084           variants of this option are for compatibility with various systems.
1085           You may use this option multiple times on the command line: it
1086           affects library searching for -l options which follow it.  This
1087           option also implies --unresolved-symbols=report-all.  This option
1088           can be used with -shared.  Doing so means that a shared library is
1089           being created but that all of the library's external references
1090           must be resolved by pulling in entries from static libraries.
1091
1092       -Bsymbolic
1093           When creating a shared library, bind references to global symbols
1094           to the definition within the shared library, if any.  Normally, it
1095           is possible for a program linked against a shared library to
1096           override the definition within the shared library.  This option is
1097           only meaningful on ELF platforms which support shared libraries.
1098
1099       -Bsymbolic-functions
1100           When creating a shared library, bind references to global function
1101           symbols to the definition within the shared library, if any.  This
1102           option is only meaningful on ELF platforms which support shared
1103           libraries.
1104
1105       --dynamic-list=dynamic-list-file
1106           Specify the name of a dynamic list file to the linker.  This is
1107           typically used when creating shared libraries to specify a list of
1108           global symbols whose references shouldn't be bound to the
1109           definition within the shared library, or creating dynamically
1110           linked executables to specify a list of symbols which should be
1111           added to the symbol table in the executable.  This option is only
1112           meaningful on ELF platforms which support shared libraries.
1113
1114           The format of the dynamic list is the same as the version node
1115           without scope and node name.  See VERSION for more information.
1116
1117       --dynamic-list-data
1118           Include all global data symbols to the dynamic list.
1119
1120       --dynamic-list-cpp-new
1121           Provide the builtin dynamic list for C++ operator new and delete.
1122           It is mainly useful for building shared libstdc++.
1123
1124       --dynamic-list-cpp-typeinfo
1125           Provide the builtin dynamic list for C++ runtime type
1126           identification.
1127
1128       --check-sections
1129       --no-check-sections
1130           Asks the linker not to check section addresses after they have been
1131           assigned to see if there are any overlaps.  Normally the linker
1132           will perform this check, and if it finds any overlaps it will
1133           produce suitable error messages.  The linker does know about, and
1134           does make allowances for sections in overlays.  The default
1135           behaviour can be restored by using the command-line switch
1136           --check-sections.  Section overlap is not usually checked for
1137           relocatable links.  You can force checking in that case by using
1138           the --check-sections option.
1139
1140       --copy-dt-needed-entries
1141       --no-copy-dt-needed-entries
1142           This option affects the treatment of dynamic libraries referred to
1143           by DT_NEEDED tags inside ELF dynamic libraries mentioned on the
1144           command line.  Normally the linker won't add a DT_NEEDED tag to the
1145           output binary for each library mentioned in a DT_NEEDED tag in an
1146           input dynamic library.  With --copy-dt-needed-entries specified on
1147           the command line however any dynamic libraries that follow it will
1148           have their DT_NEEDED entries added.  The default behaviour can be
1149           restored with --no-copy-dt-needed-entries.
1150
1151           This option also has an effect on the resolution of symbols in
1152           dynamic libraries.  With --copy-dt-needed-entries dynamic libraries
1153           mentioned on the command line will be recursively searched,
1154           following their DT_NEEDED tags to other libraries, in order to
1155           resolve symbols required by the output binary.  With the default
1156           setting however the searching of dynamic libraries that follow it
1157           will stop with the dynamic library itself.  No DT_NEEDED links will
1158           be traversed to resolve symbols.
1159
1160       --cref
1161           Output a cross reference table.  If a linker map file is being
1162           generated, the cross reference table is printed to the map file.
1163           Otherwise, it is printed on the standard output.
1164
1165           The format of the table is intentionally simple, so that it may be
1166           easily processed by a script if necessary.  The symbols are printed
1167           out, sorted by name.  For each symbol, a list of file names is
1168           given.  If the symbol is defined, the first file listed is the
1169           location of the definition.  If the symbol is defined as a common
1170           value then any files where this happens appear next.  Finally any
1171           files that reference the symbol are listed.
1172
1173       --no-define-common
1174           This option inhibits the assignment of addresses to common symbols.
1175           The script command "INHIBIT_COMMON_ALLOCATION" has the same effect.
1176
1177           The --no-define-common option allows decoupling the decision to
1178           assign addresses to Common symbols from the choice of the output
1179           file type; otherwise a non-Relocatable output type forces assigning
1180           addresses to Common symbols.  Using --no-define-common allows
1181           Common symbols that are referenced from a shared library to be
1182           assigned addresses only in the main program.  This eliminates the
1183           unused duplicate space in the shared library, and also prevents any
1184           possible confusion over resolving to the wrong duplicate when there
1185           are many dynamic modules with specialized search paths for runtime
1186           symbol resolution.
1187
1188       --force-group-allocation
1189           This option causes the linker to place section group members like
1190           normal input sections, and to delete the section groups.  This is
1191           the default behaviour for a final link but this option can be used
1192           to change the behaviour of a relocatable link (-r).  The script
1193           command "FORCE_GROUP_ALLOCATION" has the same effect.
1194
1195       --defsym=symbol=expression
1196           Create a global symbol in the output file, containing the absolute
1197           address given by expression.  You may use this option as many times
1198           as necessary to define multiple symbols in the command line.  A
1199           limited form of arithmetic is supported for the expression in this
1200           context: you may give a hexadecimal constant or the name of an
1201           existing symbol, or use "+" and "-" to add or subtract hexadecimal
1202           constants or symbols.  If you need more elaborate expressions,
1203           consider using the linker command language from a script.  Note:
1204           there should be no white space between symbol, the equals sign
1205           ("="), and expression.
1206
1207       --demangle[=style]
1208       --no-demangle
1209           These options control whether to demangle symbol names in error
1210           messages and other output.  When the linker is told to demangle, it
1211           tries to present symbol names in a readable fashion: it strips
1212           leading underscores if they are used by the object file format, and
1213           converts C++ mangled symbol names into user readable names.
1214           Different compilers have different mangling styles.  The optional
1215           demangling style argument can be used to choose an appropriate
1216           demangling style for your compiler.  The linker will demangle by
1217           default unless the environment variable COLLECT_NO_DEMANGLE is set.
1218           These options may be used to override the default.
1219
1220       -Ifile
1221       --dynamic-linker=file
1222           Set the name of the dynamic linker.  This is only meaningful when
1223           generating dynamically linked ELF executables.  The default dynamic
1224           linker is normally correct; don't use this unless you know what you
1225           are doing.
1226
1227       --no-dynamic-linker
1228           When producing an executable file, omit the request for a dynamic
1229           linker to be used at load-time.  This is only meaningful for ELF
1230           executables that contain dynamic relocations, and usually requires
1231           entry point code that is capable of processing these relocations.
1232
1233       --embedded-relocs
1234           This option is similar to the --emit-relocs option except that the
1235           relocs are stored in a target-specific section.  This option is
1236           only supported by the BFIN, CR16 and M68K targets.
1237
1238       --disable-multiple-abs-defs
1239           Do not allow multiple definitions with symbols included in filename
1240           invoked by -R or --just-symbols
1241
1242       --fatal-warnings
1243       --no-fatal-warnings
1244           Treat all warnings as errors.  The default behaviour can be
1245           restored with the option --no-fatal-warnings.
1246
1247       --force-exe-suffix
1248           Make sure that an output file has a .exe suffix.
1249
1250           If a successfully built fully linked output file does not have a
1251           ".exe" or ".dll" suffix, this option forces the linker to copy the
1252           output file to one of the same name with a ".exe" suffix. This
1253           option is useful when using unmodified Unix makefiles on a
1254           Microsoft Windows host, since some versions of Windows won't run an
1255           image unless it ends in a ".exe" suffix.
1256
1257       --gc-sections
1258       --no-gc-sections
1259           Enable garbage collection of unused input sections.  It is ignored
1260           on targets that do not support this option.  The default behaviour
1261           (of not performing this garbage collection) can be restored by
1262           specifying --no-gc-sections on the command line.  Note that garbage
1263           collection for COFF and PE format targets is supported, but the
1264           implementation is currently considered to be experimental.
1265
1266           --gc-sections decides which input sections are used by examining
1267           symbols and relocations.  The section containing the entry symbol
1268           and all sections containing symbols undefined on the command-line
1269           will be kept, as will sections containing symbols referenced by
1270           dynamic objects.  Note that when building shared libraries, the
1271           linker must assume that any visible symbol is referenced.  Once
1272           this initial set of sections has been determined, the linker
1273           recursively marks as used any section referenced by their
1274           relocations.  See --entry, --undefined, and --gc-keep-exported.
1275
1276           This option can be set when doing a partial link (enabled with
1277           option -r).  In this case the root of symbols kept must be
1278           explicitly specified either by one of the options --entry,
1279           --undefined, or --gc-keep-exported or by a "ENTRY" command in the
1280           linker script.
1281
1282       --print-gc-sections
1283       --no-print-gc-sections
1284           List all sections removed by garbage collection.  The listing is
1285           printed on stderr.  This option is only effective if garbage
1286           collection has been enabled via the --gc-sections) option.  The
1287           default behaviour (of not listing the sections that are removed)
1288           can be restored by specifying --no-print-gc-sections on the command
1289           line.
1290
1291       --gc-keep-exported
1292           When --gc-sections is enabled, this option prevents garbage
1293           collection of unused input sections that contain global symbols
1294           having default or protected visibility.  This option is intended to
1295           be used for executables where unreferenced sections would otherwise
1296           be garbage collected regardless of the external visibility of
1297           contained symbols.  Note that this option has no effect when
1298           linking shared objects since it is already the default behaviour.
1299           This option is only supported for ELF format targets.
1300
1301       --print-output-format
1302           Print the name of the default output format (perhaps influenced by
1303           other command-line options).  This is the string that would appear
1304           in an "OUTPUT_FORMAT" linker script command.
1305
1306       --print-memory-usage
1307           Print used size, total size and used size of memory regions created
1308           with the MEMORY command.  This is useful on embedded targets to
1309           have a quick view of amount of free memory.  The format of the
1310           output has one headline and one line per region.  It is both human
1311           readable and easily parsable by tools.  Here is an example of an
1312           output:
1313
1314                   Memory region         Used Size  Region Size  %age Used
1315                                ROM:        256 KB         1 MB     25.00%
1316                                RAM:          32 B         2 GB      0.00%
1317
1318       --help
1319           Print a summary of the command-line options on the standard output
1320           and exit.
1321
1322       --target-help
1323           Print a summary of all target-specific options on the standard
1324           output and exit.
1325
1326       -Map=mapfile
1327           Print a link map to the file mapfile.  See the description of the
1328           -M option, above.  Specifying a directory as mapfile causes the
1329           linker map to be written into a file inside the directory.  The
1330           name of the file is based upon the output filename with ".map"
1331           appended.
1332
1333       --no-keep-memory
1334           ld normally optimizes for speed over memory usage by caching the
1335           symbol tables of input files in memory.  This option tells ld to
1336           instead optimize for memory usage, by rereading the symbol tables
1337           as necessary.  This may be required if ld runs out of memory space
1338           while linking a large executable.
1339
1340       --no-undefined
1341       -z defs
1342           Report unresolved symbol references from regular object files.
1343           This is done even if the linker is creating a non-symbolic shared
1344           library.  The switch --[no-]allow-shlib-undefined controls the
1345           behaviour for reporting unresolved references found in shared
1346           libraries being linked in.
1347
1348           The effects of this option can be reverted by using "-z undefs".
1349
1350       --allow-multiple-definition
1351       -z muldefs
1352           Normally when a symbol is defined multiple times, the linker will
1353           report a fatal error. These options allow multiple definitions and
1354           the first definition will be used.
1355
1356       --allow-shlib-undefined
1357       --no-allow-shlib-undefined
1358           Allows or disallows undefined symbols in shared libraries.  This
1359           switch is similar to --no-undefined except that it determines the
1360           behaviour when the undefined symbols are in a shared library rather
1361           than a regular object file.  It does not affect how undefined
1362           symbols in regular object files are handled.
1363
1364           The default behaviour is to report errors for any undefined symbols
1365           referenced in shared libraries if the linker is being used to
1366           create an executable, but to allow them if the linker is being used
1367           to create a shared library.
1368
1369           The reasons for allowing undefined symbol references in shared
1370           libraries specified at link time are that:
1371
1372           •   A shared library specified at link time may not be the same as
1373               the one that is available at load time, so the symbol might
1374               actually be resolvable at load time.
1375
1376           •   There are some operating systems, eg BeOS and HPPA, where
1377               undefined symbols in shared libraries are normal.
1378
1379               The BeOS kernel for example patches shared libraries at load
1380               time to select whichever function is most appropriate for the
1381               current architecture.  This is used, for example, to
1382               dynamically select an appropriate memset function.
1383
1384       --no-undefined-version
1385           Normally when a symbol has an undefined version, the linker will
1386           ignore it. This option disallows symbols with undefined version and
1387           a fatal error will be issued instead.
1388
1389       --default-symver
1390           Create and use a default symbol version (the soname) for
1391           unversioned exported symbols.
1392
1393       --default-imported-symver
1394           Create and use a default symbol version (the soname) for
1395           unversioned imported symbols.
1396
1397       --no-warn-mismatch
1398           Normally ld will give an error if you try to link together input
1399           files that are mismatched for some reason, perhaps because they
1400           have been compiled for different processors or for different
1401           endiannesses.  This option tells ld that it should silently permit
1402           such possible errors.  This option should only be used with care,
1403           in cases when you have taken some special action that ensures that
1404           the linker errors are inappropriate.
1405
1406       --no-warn-search-mismatch
1407           Normally ld will give a warning if it finds an incompatible library
1408           during a library search.  This option silences the warning.
1409
1410       --no-whole-archive
1411           Turn off the effect of the --whole-archive option for subsequent
1412           archive files.
1413
1414       --noinhibit-exec
1415           Retain the executable output file whenever it is still usable.
1416           Normally, the linker will not produce an output file if it
1417           encounters errors during the link process; it exits without writing
1418           an output file when it issues any error whatsoever.
1419
1420       -nostdlib
1421           Only search library directories explicitly specified on the command
1422           line.  Library directories specified in linker scripts (including
1423           linker scripts specified on the command line) are ignored.
1424
1425       --oformat=output-format
1426           ld may be configured to support more than one kind of object file.
1427           If your ld is configured this way, you can use the --oformat option
1428           to specify the binary format for the output object file.  Even when
1429           ld is configured to support alternative object formats, you don't
1430           usually need to specify this, as ld should be configured to produce
1431           as a default output format the most usual format on each machine.
1432           output-format is a text string, the name of a particular format
1433           supported by the BFD libraries.  (You can list the available binary
1434           formats with objdump -i.)  The script command "OUTPUT_FORMAT" can
1435           also specify the output format, but this option overrides it.
1436
1437       --out-implib file
1438           Create an import library in file corresponding to the executable
1439           the linker is generating (eg. a DLL or ELF program).  This import
1440           library (which should be called "*.dll.a" or "*.a" for DLLs) may be
1441           used to link clients against the generated executable; this
1442           behaviour makes it possible to skip a separate import library
1443           creation step (eg. "dlltool" for DLLs).  This option is only
1444           available for the i386 PE and ELF targetted ports of the linker.
1445
1446       -pie
1447       --pic-executable
1448           Create a position independent executable.  This is currently only
1449           supported on ELF platforms.  Position independent executables are
1450           similar to shared libraries in that they are relocated by the
1451           dynamic linker to the virtual address the OS chooses for them
1452           (which can vary between invocations).  Like normal dynamically
1453           linked executables they can be executed and symbols defined in the
1454           executable cannot be overridden by shared libraries.
1455
1456       -qmagic
1457           This option is ignored for Linux compatibility.
1458
1459       -Qy This option is ignored for SVR4 compatibility.
1460
1461       --relax
1462       --no-relax
1463           An option with machine dependent effects.  This option is only
1464           supported on a few targets.
1465
1466           On some platforms the --relax option performs target-specific,
1467           global optimizations that become possible when the linker resolves
1468           addressing in the program, such as relaxing address modes,
1469           synthesizing new instructions, selecting shorter version of current
1470           instructions, and combining constant values.
1471
1472           On some platforms these link time global optimizations may make
1473           symbolic debugging of the resulting executable impossible.  This is
1474           known to be the case for the Matsushita MN10200 and MN10300 family
1475           of processors.
1476
1477           On platforms where this is not supported, --relax is accepted, but
1478           ignored.
1479
1480           On platforms where --relax is accepted the option --no-relax can be
1481           used to disable the feature.
1482
1483       --retain-symbols-file=filename
1484           Retain only the symbols listed in the file filename, discarding all
1485           others.  filename is simply a flat file, with one symbol name per
1486           line.  This option is especially useful in environments (such as
1487           VxWorks) where a large global symbol table is accumulated
1488           gradually, to conserve run-time memory.
1489
1490           --retain-symbols-file does not discard undefined symbols, or
1491           symbols needed for relocations.
1492
1493           You may only specify --retain-symbols-file once in the command
1494           line.  It overrides -s and -S.
1495
1496       -rpath=dir
1497           Add a directory to the runtime library search path.  This is used
1498           when linking an ELF executable with shared objects.  All -rpath
1499           arguments are concatenated and passed to the runtime linker, which
1500           uses them to locate shared objects at runtime.
1501
1502           The -rpath option is also used when locating shared objects which
1503           are needed by shared objects explicitly included in the link; see
1504           the description of the -rpath-link option.  Searching -rpath in
1505           this way is only supported by native linkers and cross linkers
1506           which have been configured with the --with-sysroot option.
1507
1508           If -rpath is not used when linking an ELF executable, the contents
1509           of the environment variable "LD_RUN_PATH" will be used if it is
1510           defined.
1511
1512           The -rpath option may also be used on SunOS.  By default, on SunOS,
1513           the linker will form a runtime search path out of all the -L
1514           options it is given.  If a -rpath option is used, the runtime
1515           search path will be formed exclusively using the -rpath options,
1516           ignoring the -L options.  This can be useful when using gcc, which
1517           adds many -L options which may be on NFS mounted file systems.
1518
1519           For compatibility with other ELF linkers, if the -R option is
1520           followed by a directory name, rather than a file name, it is
1521           treated as the -rpath option.
1522
1523       -rpath-link=dir
1524           When using ELF or SunOS, one shared library may require another.
1525           This happens when an "ld -shared" link includes a shared library as
1526           one of the input files.
1527
1528           When the linker encounters such a dependency when doing a non-
1529           shared, non-relocatable link, it will automatically try to locate
1530           the required shared library and include it in the link, if it is
1531           not included explicitly.  In such a case, the -rpath-link option
1532           specifies the first set of directories to search.  The -rpath-link
1533           option may specify a sequence of directory names either by
1534           specifying a list of names separated by colons, or by appearing
1535           multiple times.
1536
1537           The tokens $ORIGIN and $LIB can appear in these search directories.
1538           They will be replaced by the full path to the directory containing
1539           the program or shared object in the case of $ORIGIN and either lib
1540           - for 32-bit binaries - or lib64 - for 64-bit binaries - in the
1541           case of $LIB.
1542
1543           The alternative form of these tokens - ${ORIGIN} and ${LIB} can
1544           also be used.  The token $PLATFORM is not supported.
1545
1546           This option should be used with caution as it overrides the search
1547           path that may have been hard compiled into a shared library. In
1548           such a case it is possible to use unintentionally a different
1549           search path than the runtime linker would do.
1550
1551           The linker uses the following search paths to locate required
1552           shared libraries:
1553
1554           1.  Any directories specified by -rpath-link options.
1555
1556           2.  Any directories specified by -rpath options.  The difference
1557               between -rpath and -rpath-link is that directories specified by
1558               -rpath options are included in the executable and used at
1559               runtime, whereas the -rpath-link option is only effective at
1560               link time. Searching -rpath in this way is only supported by
1561               native linkers and cross linkers which have been configured
1562               with the --with-sysroot option.
1563
1564           3.  On an ELF system, for native linkers, if the -rpath and
1565               -rpath-link options were not used, search the contents of the
1566               environment variable "LD_RUN_PATH".
1567
1568           4.  On SunOS, if the -rpath option was not used, search any
1569               directories specified using -L options.
1570
1571           5.  For a native linker, search the contents of the environment
1572               variable "LD_LIBRARY_PATH".
1573
1574           6.  For a native ELF linker, the directories in "DT_RUNPATH" or
1575               "DT_RPATH" of a shared library are searched for shared
1576               libraries needed by it. The "DT_RPATH" entries are ignored if
1577               "DT_RUNPATH" entries exist.
1578
1579           7.  The default directories, normally /lib and /usr/lib.
1580
1581           8.  For a linker for a Linux system, if the file /etc/ld.so.conf
1582               exists, the list of directories found in that file.  Note: the
1583               path to this file is prefixed with the "sysroot" value, if that
1584               is defined, and then any "prefix" string if the linker was
1585               configured with the --prefix=<path> option.
1586
1587           9.  For a native linker on a FreeBSD system, any directories
1588               specified by the "_PATH_ELF_HINTS" macro defined in the
1589               elf-hints.h header file.
1590
1591           10. Any directories specifed by a "SEARCH_DIR" command in the
1592               linker script being used.
1593
1594           If the required shared library is not found, the linker will issue
1595           a warning and continue with the link.
1596
1597       -shared
1598       -Bshareable
1599           Create a shared library.  This is currently only supported on ELF,
1600           XCOFF and SunOS platforms.  On SunOS, the linker will automatically
1601           create a shared library if the -e option is not used and there are
1602           undefined symbols in the link.
1603
1604       --sort-common
1605       --sort-common=ascending
1606       --sort-common=descending
1607           This option tells ld to sort the common symbols by alignment in
1608           ascending or descending order when it places them in the
1609           appropriate output sections.  The symbol alignments considered are
1610           sixteen-byte or larger, eight-byte, four-byte, two-byte, and one-
1611           byte. This is to prevent gaps between symbols due to alignment
1612           constraints.  If no sorting order is specified, then descending
1613           order is assumed.
1614
1615       --sort-section=name
1616           This option will apply "SORT_BY_NAME" to all wildcard section
1617           patterns in the linker script.
1618
1619       --sort-section=alignment
1620           This option will apply "SORT_BY_ALIGNMENT" to all wildcard section
1621           patterns in the linker script.
1622
1623       --spare-dynamic-tags=count
1624           This option specifies the number of empty slots to leave in the
1625           .dynamic section of ELF shared objects.  Empty slots may be needed
1626           by post processing tools, such as the prelinker.  The default is 5.
1627
1628       --split-by-file[=size]
1629           Similar to --split-by-reloc but creates a new output section for
1630           each input file when size is reached.  size defaults to a size of 1
1631           if not given.
1632
1633       --split-by-reloc[=count]
1634           Tries to creates extra sections in the output file so that no
1635           single output section in the file contains more than count
1636           relocations.  This is useful when generating huge relocatable files
1637           for downloading into certain real time kernels with the COFF object
1638           file format; since COFF cannot represent more than 65535
1639           relocations in a single section.  Note that this will fail to work
1640           with object file formats which do not support arbitrary sections.
1641           The linker will not split up individual input sections for
1642           redistribution, so if a single input section contains more than
1643           count relocations one output section will contain that many
1644           relocations.  count defaults to a value of 32768.
1645
1646       --stats
1647           Compute and display statistics about the operation of the linker,
1648           such as execution time and memory usage.
1649
1650       --sysroot=directory
1651           Use directory as the location of the sysroot, overriding the
1652           configure-time default.  This option is only supported by linkers
1653           that were configured using --with-sysroot.
1654
1655       --task-link
1656           This is used by COFF/PE based targets to create a task-linked
1657           object file where all of the global symbols have been converted to
1658           statics.
1659
1660       --traditional-format
1661           For some targets, the output of ld is different in some ways from
1662           the output of some existing linker.  This switch requests ld to use
1663           the traditional format instead.
1664
1665           For example, on SunOS, ld combines duplicate entries in the symbol
1666           string table.  This can reduce the size of an output file with full
1667           debugging information by over 30 percent.  Unfortunately, the SunOS
1668           "dbx" program can not read the resulting program ("gdb" has no
1669           trouble).  The --traditional-format switch tells ld to not combine
1670           duplicate entries.
1671
1672       --section-start=sectionname=org
1673           Locate a section in the output file at the absolute address given
1674           by org.  You may use this option as many times as necessary to
1675           locate multiple sections in the command line.  org must be a single
1676           hexadecimal integer; for compatibility with other linkers, you may
1677           omit the leading 0x usually associated with hexadecimal values.
1678           Note: there should be no white space between sectionname, the
1679           equals sign ("="), and org.
1680
1681       -Tbss=org
1682       -Tdata=org
1683       -Ttext=org
1684           Same as --section-start, with ".bss", ".data" or ".text" as the
1685           sectionname.
1686
1687       -Ttext-segment=org
1688           When creating an ELF executable, it will set the address of the
1689           first byte of the text segment.
1690
1691       -Trodata-segment=org
1692           When creating an ELF executable or shared object for a target where
1693           the read-only data is in its own segment separate from the
1694           executable text, it will set the address of the first byte of the
1695           read-only data segment.
1696
1697       -Tldata-segment=org
1698           When creating an ELF executable or shared object for x86-64 medium
1699           memory model, it will set the address of the first byte of the
1700           ldata segment.
1701
1702       --unresolved-symbols=method
1703           Determine how to handle unresolved symbols.  There are four
1704           possible values for method:
1705
1706           ignore-all
1707               Do not report any unresolved symbols.
1708
1709           report-all
1710               Report all unresolved symbols.  This is the default.
1711
1712           ignore-in-object-files
1713               Report unresolved symbols that are contained in shared
1714               libraries, but ignore them if they come from regular object
1715               files.
1716
1717           ignore-in-shared-libs
1718               Report unresolved symbols that come from regular object files,
1719               but ignore them if they come from shared libraries.  This can
1720               be useful when creating a dynamic binary and it is known that
1721               all the shared libraries that it should be referencing are
1722               included on the linker's command line.
1723
1724           The behaviour for shared libraries on their own can also be
1725           controlled by the --[no-]allow-shlib-undefined option.
1726
1727           Normally the linker will generate an error message for each
1728           reported unresolved symbol but the option --warn-unresolved-symbols
1729           can change this to a warning.
1730
1731       --dll-verbose
1732       --verbose[=NUMBER]
1733           Display the version number for ld and list the linker emulations
1734           supported.  Display which input files can and cannot be opened.
1735           Display the linker script being used by the linker. If the optional
1736           NUMBER argument > 1, plugin symbol status will also be displayed.
1737
1738       --version-script=version-scriptfile
1739           Specify the name of a version script to the linker.  This is
1740           typically used when creating shared libraries to specify additional
1741           information about the version hierarchy for the library being
1742           created.  This option is only fully supported on ELF platforms
1743           which support shared libraries; see VERSION.  It is partially
1744           supported on PE platforms, which can use version scripts to filter
1745           symbol visibility in auto-export mode: any symbols marked local in
1746           the version script will not be exported.
1747
1748       --warn-common
1749           Warn when a common symbol is combined with another common symbol or
1750           with a symbol definition.  Unix linkers allow this somewhat sloppy
1751           practice, but linkers on some other operating systems do not.  This
1752           option allows you to find potential problems from combining global
1753           symbols.  Unfortunately, some C libraries use this practice, so you
1754           may get some warnings about symbols in the libraries as well as in
1755           your programs.
1756
1757           There are three kinds of global symbols, illustrated here by C
1758           examples:
1759
1760           int i = 1;
1761               A definition, which goes in the initialized data section of the
1762               output file.
1763
1764           extern int i;
1765               An undefined reference, which does not allocate space.  There
1766               must be either a definition or a common symbol for the variable
1767               somewhere.
1768
1769           int i;
1770               A common symbol.  If there are only (one or more) common
1771               symbols for a variable, it goes in the uninitialized data area
1772               of the output file.  The linker merges multiple common symbols
1773               for the same variable into a single symbol.  If they are of
1774               different sizes, it picks the largest size.  The linker turns a
1775               common symbol into a declaration, if there is a definition of
1776               the same variable.
1777
1778           The --warn-common option can produce five kinds of warnings.  Each
1779           warning consists of a pair of lines: the first describes the symbol
1780           just encountered, and the second describes the previous symbol
1781           encountered with the same name.  One or both of the two symbols
1782           will be a common symbol.
1783
1784           1.  Turning a common symbol into a reference, because there is
1785               already a definition for the symbol.
1786
1787                       <file>(<section>): warning: common of `<symbol>'
1788                          overridden by definition
1789                       <file>(<section>): warning: defined here
1790
1791           2.  Turning a common symbol into a reference, because a later
1792               definition for the symbol is encountered.  This is the same as
1793               the previous case, except that the symbols are encountered in a
1794               different order.
1795
1796                       <file>(<section>): warning: definition of `<symbol>'
1797                          overriding common
1798                       <file>(<section>): warning: common is here
1799
1800           3.  Merging a common symbol with a previous same-sized common
1801               symbol.
1802
1803                       <file>(<section>): warning: multiple common
1804                          of `<symbol>'
1805                       <file>(<section>): warning: previous common is here
1806
1807           4.  Merging a common symbol with a previous larger common symbol.
1808
1809                       <file>(<section>): warning: common of `<symbol>'
1810                          overridden by larger common
1811                       <file>(<section>): warning: larger common is here
1812
1813           5.  Merging a common symbol with a previous smaller common symbol.
1814               This is the same as the previous case, except that the symbols
1815               are encountered in a different order.
1816
1817                       <file>(<section>): warning: common of `<symbol>'
1818                          overriding smaller common
1819                       <file>(<section>): warning: smaller common is here
1820
1821       --warn-constructors
1822           Warn if any global constructors are used.  This is only useful for
1823           a few object file formats.  For formats like COFF or ELF, the
1824           linker can not detect the use of global constructors.
1825
1826       --warn-multiple-gp
1827           Warn if multiple global pointer values are required in the output
1828           file.  This is only meaningful for certain processors, such as the
1829           Alpha.  Specifically, some processors put large-valued constants in
1830           a special section.  A special register (the global pointer) points
1831           into the middle of this section, so that constants can be loaded
1832           efficiently via a base-register relative addressing mode.  Since
1833           the offset in base-register relative mode is fixed and relatively
1834           small (e.g., 16 bits), this limits the maximum size of the constant
1835           pool.  Thus, in large programs, it is often necessary to use
1836           multiple global pointer values in order to be able to address all
1837           possible constants.  This option causes a warning to be issued
1838           whenever this case occurs.
1839
1840       --warn-once
1841           Only warn once for each undefined symbol, rather than once per
1842           module which refers to it.
1843
1844       --warn-section-align
1845           Warn if the address of an output section is changed because of
1846           alignment.  Typically, the alignment will be set by an input
1847           section.  The address will only be changed if it not explicitly
1848           specified; that is, if the "SECTIONS" command does not specify a
1849           start address for the section.
1850
1851       --warn-textrel
1852           Warn if the linker adds DT_TEXTREL to a position-independent
1853           executable or shared object.
1854
1855       --warn-alternate-em
1856           Warn if an object has alternate ELF machine code.
1857
1858       --warn-unresolved-symbols
1859           If the linker is going to report an unresolved symbol (see the
1860           option --unresolved-symbols) it will normally generate an error.
1861           This option makes it generate a warning instead.
1862
1863       --error-unresolved-symbols
1864           This restores the linker's default behaviour of generating errors
1865           when it is reporting unresolved symbols.
1866
1867       --whole-archive
1868           For each archive mentioned on the command line after the
1869           --whole-archive option, include every object file in the archive in
1870           the link, rather than searching the archive for the required object
1871           files.  This is normally used to turn an archive file into a shared
1872           library, forcing every object to be included in the resulting
1873           shared library.  This option may be used more than once.
1874
1875           Two notes when using this option from gcc: First, gcc doesn't know
1876           about this option, so you have to use -Wl,-whole-archive.  Second,
1877           don't forget to use -Wl,-no-whole-archive after your list of
1878           archives, because gcc will add its own list of archives to your
1879           link and you may not want this flag to affect those as well.
1880
1881       --wrap=symbol
1882           Use a wrapper function for symbol.  Any undefined reference to
1883           symbol will be resolved to "__wrap_symbol".  Any undefined
1884           reference to "__real_symbol" will be resolved to symbol.
1885
1886           This can be used to provide a wrapper for a system function.  The
1887           wrapper function should be called "__wrap_symbol".  If it wishes to
1888           call the system function, it should call "__real_symbol".
1889
1890           Here is a trivial example:
1891
1892                   void *
1893                   __wrap_malloc (size_t c)
1894                   {
1895                     printf ("malloc called with %zu\n", c);
1896                     return __real_malloc (c);
1897                   }
1898
1899           If you link other code with this file using --wrap malloc, then all
1900           calls to "malloc" will call the function "__wrap_malloc" instead.
1901           The call to "__real_malloc" in "__wrap_malloc" will call the real
1902           "malloc" function.
1903
1904           You may wish to provide a "__real_malloc" function as well, so that
1905           links without the --wrap option will succeed.  If you do this, you
1906           should not put the definition of "__real_malloc" in the same file
1907           as "__wrap_malloc"; if you do, the assembler may resolve the call
1908           before the linker has a chance to wrap it to "malloc".
1909
1910           Only undefined references are replaced by the linker.  So,
1911           translation unit internal references to symbol are not resolved to
1912           "__wrap_symbol".  In the next example, the call to "f" in "g" is
1913           not resolved to "__wrap_f".
1914
1915                   int
1916                   f (void)
1917                   {
1918                     return 123;
1919                   }
1920
1921                   int
1922                   g (void)
1923                   {
1924                     return f();
1925                   }
1926
1927       --eh-frame-hdr
1928       --no-eh-frame-hdr
1929           Request (--eh-frame-hdr) or suppress (--no-eh-frame-hdr) the
1930           creation of ".eh_frame_hdr" section and ELF "PT_GNU_EH_FRAME"
1931           segment header.
1932
1933       --no-ld-generated-unwind-info
1934           Request creation of ".eh_frame" unwind info for linker generated
1935           code sections like PLT.  This option is on by default if linker
1936           generated unwind info is supported.
1937
1938       --enable-new-dtags
1939       --disable-new-dtags
1940           This linker can create the new dynamic tags in ELF. But the older
1941           ELF systems may not understand them. If you specify
1942           --enable-new-dtags, the new dynamic tags will be created as needed
1943           and older dynamic tags will be omitted.  If you specify
1944           --disable-new-dtags, no new dynamic tags will be created. By
1945           default, the new dynamic tags are not created. Note that those
1946           options are only available for ELF systems.
1947
1948       --hash-size=number
1949           Set the default size of the linker's hash tables to a prime number
1950           close to number.  Increasing this value can reduce the length of
1951           time it takes the linker to perform its tasks, at the expense of
1952           increasing the linker's memory requirements.  Similarly reducing
1953           this value can reduce the memory requirements at the expense of
1954           speed.
1955
1956       --hash-style=style
1957           Set the type of linker's hash table(s).  style can be either "sysv"
1958           for classic ELF ".hash" section, "gnu" for new style GNU
1959           ".gnu.hash" section or "both" for both the classic ELF ".hash" and
1960           new style GNU ".gnu.hash" hash tables.  The default depends upon
1961           how the linker was configured, but for most Linux based systems it
1962           will be "both".
1963
1964       --compress-debug-sections=none
1965       --compress-debug-sections=zlib
1966       --compress-debug-sections=zlib-gnu
1967       --compress-debug-sections=zlib-gabi
1968           On ELF platforms, these options control how DWARF debug sections
1969           are compressed using zlib.
1970
1971           --compress-debug-sections=none doesn't compress DWARF debug
1972           sections.  --compress-debug-sections=zlib-gnu compresses DWARF
1973           debug sections and renames them to begin with .zdebug instead of
1974           .debug.  --compress-debug-sections=zlib-gabi also compresses DWARF
1975           debug sections, but rather than renaming them it sets the
1976           SHF_COMPRESSED flag in the sections' headers.
1977
1978           The --compress-debug-sections=zlib option is an alias for
1979           --compress-debug-sections=zlib-gabi.
1980
1981           Note that this option overrides any compression in input debug
1982           sections, so if a binary is linked with
1983           --compress-debug-sections=none for example, then any compressed
1984           debug sections in input files will be uncompressed before they are
1985           copied into the output binary.
1986
1987           The default compression behaviour varies depending upon the target
1988           involved and the configure options used to build the toolchain.
1989           The default can be determined by examining the output from the
1990           linker's --help option.
1991
1992       --reduce-memory-overheads
1993           This option reduces memory requirements at ld runtime, at the
1994           expense of linking speed.  This was introduced to select the old
1995           O(n^2) algorithm for link map file generation, rather than the new
1996           O(n) algorithm which uses about 40% more memory for symbol storage.
1997
1998           Another effect of the switch is to set the default hash table size
1999           to 1021, which again saves memory at the cost of lengthening the
2000           linker's run time.  This is not done however if the --hash-size
2001           switch has been used.
2002
2003           The --reduce-memory-overheads switch may be also be used to enable
2004           other tradeoffs in future versions of the linker.
2005
2006       --build-id
2007       --build-id=style
2008           Request the creation of a ".note.gnu.build-id" ELF note section or
2009           a ".buildid" COFF section.  The contents of the note are unique
2010           bits identifying this linked file.  style can be "uuid" to use 128
2011           random bits, "sha1" to use a 160-bit SHA1 hash on the normative
2012           parts of the output contents, "md5" to use a 128-bit MD5 hash on
2013           the normative parts of the output contents, or "0xhexstring" to use
2014           a chosen bit string specified as an even number of hexadecimal
2015           digits ("-" and ":" characters between digit pairs are ignored).
2016           If style is omitted, "sha1" is used.
2017
2018           The "md5" and "sha1" styles produces an identifier that is always
2019           the same in an identical output file, but will be unique among all
2020           nonidentical output files.  It is not intended to be compared as a
2021           checksum for the file's contents.  A linked file may be changed
2022           later by other tools, but the build ID bit string identifying the
2023           original linked file does not change.
2024
2025           Passing "none" for style disables the setting from any "--build-id"
2026           options earlier on the command line.
2027
2028       The i386 PE linker supports the -shared option, which causes the output
2029       to be a dynamically linked library (DLL) instead of a normal
2030       executable.  You should name the output "*.dll" when you use this
2031       option.  In addition, the linker fully supports the standard "*.def"
2032       files, which may be specified on the linker command line like an object
2033       file (in fact, it should precede archives it exports symbols from, to
2034       ensure that they get linked in, just like a normal object file).
2035
2036       In addition to the options common to all targets, the i386 PE linker
2037       support additional command-line options that are specific to the i386
2038       PE target.  Options that take values may be separated from their values
2039       by either a space or an equals sign.
2040
2041       --add-stdcall-alias
2042           If given, symbols with a stdcall suffix (@nn) will be exported as-
2043           is and also with the suffix stripped.  [This option is specific to
2044           the i386 PE targeted port of the linker]
2045
2046       --base-file file
2047           Use file as the name of a file in which to save the base addresses
2048           of all the relocations needed for generating DLLs with dlltool.
2049           [This is an i386 PE specific option]
2050
2051       --dll
2052           Create a DLL instead of a regular executable.  You may also use
2053           -shared or specify a "LIBRARY" in a given ".def" file.  [This
2054           option is specific to the i386 PE targeted port of the linker]
2055
2056       --enable-long-section-names
2057       --disable-long-section-names
2058           The PE variants of the COFF object format add an extension that
2059           permits the use of section names longer than eight characters, the
2060           normal limit for COFF.  By default, these names are only allowed in
2061           object files, as fully-linked executable images do not carry the
2062           COFF string table required to support the longer names.  As a GNU
2063           extension, it is possible to allow their use in executable images
2064           as well, or to (probably pointlessly!)  disallow it in object
2065           files, by using these two options.  Executable images generated
2066           with these long section names are slightly non-standard, carrying
2067           as they do a string table, and may generate confusing output when
2068           examined with non-GNU PE-aware tools, such as file viewers and
2069           dumpers.  However, GDB relies on the use of PE long section names
2070           to find Dwarf-2 debug information sections in an executable image
2071           at runtime, and so if neither option is specified on the command-
2072           line, ld will enable long section names, overriding the default and
2073           technically correct behaviour, when it finds the presence of debug
2074           information while linking an executable image and not stripping
2075           symbols.  [This option is valid for all PE targeted ports of the
2076           linker]
2077
2078       --enable-stdcall-fixup
2079       --disable-stdcall-fixup
2080           If the link finds a symbol that it cannot resolve, it will attempt
2081           to do "fuzzy linking" by looking for another defined symbol that
2082           differs only in the format of the symbol name (cdecl vs stdcall)
2083           and will resolve that symbol by linking to the match.  For example,
2084           the undefined symbol "_foo" might be linked to the function
2085           "_foo@12", or the undefined symbol "_bar@16" might be linked to the
2086           function "_bar".  When the linker does this, it prints a warning,
2087           since it normally should have failed to link, but sometimes import
2088           libraries generated from third-party dlls may need this feature to
2089           be usable.  If you specify --enable-stdcall-fixup, this feature is
2090           fully enabled and warnings are not printed.  If you specify
2091           --disable-stdcall-fixup, this feature is disabled and such
2092           mismatches are considered to be errors.  [This option is specific
2093           to the i386 PE targeted port of the linker]
2094
2095       --leading-underscore
2096       --no-leading-underscore
2097           For most targets default symbol-prefix is an underscore and is
2098           defined in target's description. By this option it is possible to
2099           disable/enable the default underscore symbol-prefix.
2100
2101       --export-all-symbols
2102           If given, all global symbols in the objects used to build a DLL
2103           will be exported by the DLL.  Note that this is the default if
2104           there otherwise wouldn't be any exported symbols.  When symbols are
2105           explicitly exported via DEF files or implicitly exported via
2106           function attributes, the default is to not export anything else
2107           unless this option is given.  Note that the symbols "DllMain@12",
2108           "DllEntryPoint@0", "DllMainCRTStartup@12", and "impure_ptr" will
2109           not be automatically exported.  Also, symbols imported from other
2110           DLLs will not be re-exported, nor will symbols specifying the DLL's
2111           internal layout such as those beginning with "_head_" or ending
2112           with "_iname".  In addition, no symbols from "libgcc", "libstd++",
2113           "libmingw32", or "crtX.o" will be exported.  Symbols whose names
2114           begin with "__rtti_" or "__builtin_" will not be exported, to help
2115           with C++ DLLs.  Finally, there is an extensive list of cygwin-
2116           private symbols that are not exported (obviously, this applies on
2117           when building DLLs for cygwin targets).  These cygwin-excludes are:
2118           "_cygwin_dll_entry@12", "_cygwin_crt0_common@8",
2119           "_cygwin_noncygwin_dll_entry@12", "_fmode", "_impure_ptr",
2120           "cygwin_attach_dll", "cygwin_premain0", "cygwin_premain1",
2121           "cygwin_premain2", "cygwin_premain3", and "environ".  [This option
2122           is specific to the i386 PE targeted port of the linker]
2123
2124       --exclude-symbols symbol,symbol,...
2125           Specifies a list of symbols which should not be automatically
2126           exported.  The symbol names may be delimited by commas or colons.
2127           [This option is specific to the i386 PE targeted port of the
2128           linker]
2129
2130       --exclude-all-symbols
2131           Specifies no symbols should be automatically exported.  [This
2132           option is specific to the i386 PE targeted port of the linker]
2133
2134       --file-alignment
2135           Specify the file alignment.  Sections in the file will always begin
2136           at file offsets which are multiples of this number.  This defaults
2137           to 512.  [This option is specific to the i386 PE targeted port of
2138           the linker]
2139
2140       --heap reserve
2141       --heap reserve,commit
2142           Specify the number of bytes of memory to reserve (and optionally
2143           commit) to be used as heap for this program.  The default is 1MB
2144           reserved, 4K committed.  [This option is specific to the i386 PE
2145           targeted port of the linker]
2146
2147       --image-base value
2148           Use value as the base address of your program or dll.  This is the
2149           lowest memory location that will be used when your program or dll
2150           is loaded.  To reduce the need to relocate and improve performance
2151           of your dlls, each should have a unique base address and not
2152           overlap any other dlls.  The default is 0x400000 for executables,
2153           and 0x10000000 for dlls.  [This option is specific to the i386 PE
2154           targeted port of the linker]
2155
2156       --kill-at
2157           If given, the stdcall suffixes (@nn) will be stripped from symbols
2158           before they are exported.  [This option is specific to the i386 PE
2159           targeted port of the linker]
2160
2161       --large-address-aware
2162           If given, the appropriate bit in the "Characteristics" field of the
2163           COFF header is set to indicate that this executable supports
2164           virtual addresses greater than 2 gigabytes.  This should be used in
2165           conjunction with the /3GB or /USERVA=value megabytes switch in the
2166           "[operating systems]" section of the BOOT.INI.  Otherwise, this bit
2167           has no effect.  [This option is specific to PE targeted ports of
2168           the linker]
2169
2170       --disable-large-address-aware
2171           Reverts the effect of a previous --large-address-aware option.
2172           This is useful if --large-address-aware is always set by the
2173           compiler driver (e.g. Cygwin gcc) and the executable does not
2174           support virtual addresses greater than 2 gigabytes.  [This option
2175           is specific to PE targeted ports of the linker]
2176
2177       --major-image-version value
2178           Sets the major number of the "image version".  Defaults to 1.
2179           [This option is specific to the i386 PE targeted port of the
2180           linker]
2181
2182       --major-os-version value
2183           Sets the major number of the "os version".  Defaults to 4.  [This
2184           option is specific to the i386 PE targeted port of the linker]
2185
2186       --major-subsystem-version value
2187           Sets the major number of the "subsystem version".  Defaults to 4.
2188           [This option is specific to the i386 PE targeted port of the
2189           linker]
2190
2191       --minor-image-version value
2192           Sets the minor number of the "image version".  Defaults to 0.
2193           [This option is specific to the i386 PE targeted port of the
2194           linker]
2195
2196       --minor-os-version value
2197           Sets the minor number of the "os version".  Defaults to 0.  [This
2198           option is specific to the i386 PE targeted port of the linker]
2199
2200       --minor-subsystem-version value
2201           Sets the minor number of the "subsystem version".  Defaults to 0.
2202           [This option is specific to the i386 PE targeted port of the
2203           linker]
2204
2205       --output-def file
2206           The linker will create the file file which will contain a DEF file
2207           corresponding to the DLL the linker is generating.  This DEF file
2208           (which should be called "*.def") may be used to create an import
2209           library with "dlltool" or may be used as a reference to
2210           automatically or implicitly exported symbols.  [This option is
2211           specific to the i386 PE targeted port of the linker]
2212
2213       --enable-auto-image-base
2214       --enable-auto-image-base=value
2215           Automatically choose the image base for DLLs, optionally starting
2216           with base value, unless one is specified using the "--image-base"
2217           argument.  By using a hash generated from the dllname to create
2218           unique image bases for each DLL, in-memory collisions and
2219           relocations which can delay program execution are avoided.  [This
2220           option is specific to the i386 PE targeted port of the linker]
2221
2222       --disable-auto-image-base
2223           Do not automatically generate a unique image base.  If there is no
2224           user-specified image base ("--image-base") then use the platform
2225           default.  [This option is specific to the i386 PE targeted port of
2226           the linker]
2227
2228       --dll-search-prefix string
2229           When linking dynamically to a dll without an import library, search
2230           for "<string><basename>.dll" in preference to "lib<basename>.dll".
2231           This behaviour allows easy distinction between DLLs built for the
2232           various "subplatforms": native, cygwin, uwin, pw, etc.  For
2233           instance, cygwin DLLs typically use "--dll-search-prefix=cyg".
2234           [This option is specific to the i386 PE targeted port of the
2235           linker]
2236
2237       --enable-auto-import
2238           Do sophisticated linking of "_symbol" to "__imp__symbol" for DATA
2239           imports from DLLs, thus making it possible to bypass the dllimport
2240           mechanism on the user side and to reference unmangled symbol names.
2241           [This option is specific to the i386 PE targeted port of the
2242           linker]
2243
2244           The following remarks pertain to the original implementation of the
2245           feature and are obsolete nowadays for Cygwin and MinGW targets.
2246
2247           Note: Use of the 'auto-import' extension will cause the text
2248           section of the image file to be made writable. This does not
2249           conform to the PE-COFF format specification published by Microsoft.
2250
2251           Note - use of the 'auto-import' extension will also cause read only
2252           data which would normally be placed into the .rdata section to be
2253           placed into the .data section instead.  This is in order to work
2254           around a problem with consts that is described here:
2255           http://www.cygwin.com/ml/cygwin/2004-09/msg01101.html
2256
2257           Using 'auto-import' generally will 'just work' -- but sometimes you
2258           may see this message:
2259
2260           "variable '<var>' can't be auto-imported. Please read the
2261           documentation for ld's "--enable-auto-import" for details."
2262
2263           This message occurs when some (sub)expression accesses an address
2264           ultimately given by the sum of two constants (Win32 import tables
2265           only allow one).  Instances where this may occur include accesses
2266           to member fields of struct variables imported from a DLL, as well
2267           as using a constant index into an array variable imported from a
2268           DLL.  Any multiword variable (arrays, structs, long long, etc) may
2269           trigger this error condition.  However, regardless of the exact
2270           data type of the offending exported variable, ld will always detect
2271           it, issue the warning, and exit.
2272
2273           There are several ways to address this difficulty, regardless of
2274           the data type of the exported variable:
2275
2276           One way is to use --enable-runtime-pseudo-reloc switch. This leaves
2277           the task of adjusting references in your client code for runtime
2278           environment, so this method works only when runtime environment
2279           supports this feature.
2280
2281           A second solution is to force one of the 'constants' to be a
2282           variable -- that is, unknown and un-optimizable at compile time.
2283           For arrays, there are two possibilities: a) make the indexee (the
2284           array's address) a variable, or b) make the 'constant' index a
2285           variable.  Thus:
2286
2287                   extern type extern_array[];
2288                   extern_array[1] -->
2289                      { volatile type *t=extern_array; t[1] }
2290
2291           or
2292
2293                   extern type extern_array[];
2294                   extern_array[1] -->
2295                      { volatile int t=1; extern_array[t] }
2296
2297           For structs (and most other multiword data types) the only option
2298           is to make the struct itself (or the long long, or the ...)
2299           variable:
2300
2301                   extern struct s extern_struct;
2302                   extern_struct.field -->
2303                      { volatile struct s *t=&extern_struct; t->field }
2304
2305           or
2306
2307                   extern long long extern_ll;
2308                   extern_ll -->
2309                     { volatile long long * local_ll=&extern_ll; *local_ll }
2310
2311           A third method of dealing with this difficulty is to abandon
2312           'auto-import' for the offending symbol and mark it with
2313           "__declspec(dllimport)".  However, in practice that requires using
2314           compile-time #defines to indicate whether you are building a DLL,
2315           building client code that will link to the DLL, or merely
2316           building/linking to a static library.   In making the choice
2317           between the various methods of resolving the 'direct address with
2318           constant offset' problem, you should consider typical real-world
2319           usage:
2320
2321           Original:
2322
2323                   --foo.h
2324                   extern int arr[];
2325                   --foo.c
2326                   #include "foo.h"
2327                   void main(int argc, char **argv){
2328                     printf("%d\n",arr[1]);
2329                   }
2330
2331           Solution 1:
2332
2333                   --foo.h
2334                   extern int arr[];
2335                   --foo.c
2336                   #include "foo.h"
2337                   void main(int argc, char **argv){
2338                     /* This workaround is for win32 and cygwin; do not "optimize" */
2339                     volatile int *parr = arr;
2340                     printf("%d\n",parr[1]);
2341                   }
2342
2343           Solution 2:
2344
2345                   --foo.h
2346                   /* Note: auto-export is assumed (no __declspec(dllexport)) */
2347                   #if (defined(_WIN32) || defined(__CYGWIN__)) && \
2348                     !(defined(FOO_BUILD_DLL) || defined(FOO_STATIC))
2349                   #define FOO_IMPORT __declspec(dllimport)
2350                   #else
2351                   #define FOO_IMPORT
2352                   #endif
2353                   extern FOO_IMPORT int arr[];
2354                   --foo.c
2355                   #include "foo.h"
2356                   void main(int argc, char **argv){
2357                     printf("%d\n",arr[1]);
2358                   }
2359
2360           A fourth way to avoid this problem is to re-code your library to
2361           use a functional interface rather than a data interface for the
2362           offending variables (e.g. set_foo() and get_foo() accessor
2363           functions).
2364
2365       --disable-auto-import
2366           Do not attempt to do sophisticated linking of "_symbol" to
2367           "__imp__symbol" for DATA imports from DLLs.  [This option is
2368           specific to the i386 PE targeted port of the linker]
2369
2370       --enable-runtime-pseudo-reloc
2371           If your code contains expressions described in --enable-auto-import
2372           section, that is, DATA imports from DLL with non-zero offset, this
2373           switch will create a vector of 'runtime pseudo relocations' which
2374           can be used by runtime environment to adjust references to such
2375           data in your client code.  [This option is specific to the i386 PE
2376           targeted port of the linker]
2377
2378       --disable-runtime-pseudo-reloc
2379           Do not create pseudo relocations for non-zero offset DATA imports
2380           from DLLs.  [This option is specific to the i386 PE targeted port
2381           of the linker]
2382
2383       --enable-extra-pe-debug
2384           Show additional debug info related to auto-import symbol thunking.
2385           [This option is specific to the i386 PE targeted port of the
2386           linker]
2387
2388       --section-alignment
2389           Sets the section alignment.  Sections in memory will always begin
2390           at addresses which are a multiple of this number.  Defaults to
2391           0x1000.  [This option is specific to the i386 PE targeted port of
2392           the linker]
2393
2394       --stack reserve
2395       --stack reserve,commit
2396           Specify the number of bytes of memory to reserve (and optionally
2397           commit) to be used as stack for this program.  The default is 2MB
2398           reserved, 4K committed.  [This option is specific to the i386 PE
2399           targeted port of the linker]
2400
2401       --subsystem which
2402       --subsystem which:major
2403       --subsystem which:major.minor
2404           Specifies the subsystem under which your program will execute.  The
2405           legal values for which are "native", "windows", "console", "posix",
2406           and "xbox".  You may optionally set the subsystem version also.
2407           Numeric values are also accepted for which.  [This option is
2408           specific to the i386 PE targeted port of the linker]
2409
2410           The following options set flags in the "DllCharacteristics" field
2411           of the PE file header: [These options are specific to PE targeted
2412           ports of the linker]
2413
2414       --high-entropy-va
2415           Image is compatible with 64-bit address space layout randomization
2416           (ASLR).  This option also implies --dynamicbase and
2417           --enable-reloc-section.
2418
2419       --dynamicbase
2420           The image base address may be relocated using address space layout
2421           randomization (ASLR).  This feature was introduced with MS Windows
2422           Vista for i386 PE targets.  This option also implies
2423           --enable-reloc-section.
2424
2425       --forceinteg
2426           Code integrity checks are enforced.
2427
2428       --nxcompat
2429           The image is compatible with the Data Execution Prevention.  This
2430           feature was introduced with MS Windows XP SP2 for i386 PE targets.
2431
2432       --no-isolation
2433           Although the image understands isolation, do not isolate the image.
2434
2435       --no-seh
2436           The image does not use SEH. No SE handler may be called from this
2437           image.
2438
2439       --no-bind
2440           Do not bind this image.
2441
2442       --wdmdriver
2443           The driver uses the MS Windows Driver Model.
2444
2445       --tsaware
2446           The image is Terminal Server aware.
2447
2448       --insert-timestamp
2449       --no-insert-timestamp
2450           Insert a real timestamp into the image.  This is the default
2451           behaviour as it matches legacy code and it means that the image
2452           will work with other, proprietary tools.  The problem with this
2453           default is that it will result in slightly different images being
2454           produced each time the same sources are linked.  The option
2455           --no-insert-timestamp can be used to insert a zero value for the
2456           timestamp, this ensuring that binaries produced from identical
2457           sources will compare identically.
2458
2459       --enable-reloc-section
2460           Create the base relocation table, which is necessary if the image
2461           is loaded at a different image base than specified in the PE
2462           header.
2463
2464       The C6X uClinux target uses a binary format called DSBT to support
2465       shared libraries.  Each shared library in the system needs to have a
2466       unique index; all executables use an index of 0.
2467
2468       --dsbt-size size
2469           This option sets the number of entries in the DSBT of the current
2470           executable or shared library to size.  The default is to create a
2471           table with 64 entries.
2472
2473       --dsbt-index index
2474           This option sets the DSBT index of the current executable or shared
2475           library to index.  The default is 0, which is appropriate for
2476           generating executables.  If a shared library is generated with a
2477           DSBT index of 0, the "R_C6000_DSBT_INDEX" relocs are copied into
2478           the output file.
2479
2480           The --no-merge-exidx-entries switch disables the merging of
2481           adjacent exidx entries in frame unwind info.
2482
2483       --branch-stub
2484           This option enables linker branch relaxation by inserting branch
2485           stub sections when needed to extend the range of branches.  This
2486           option is usually not required since C-SKY supports branch and call
2487           instructions that can access the full memory range and branch
2488           relaxation is normally handled by the compiler or assembler.
2489
2490       --stub-group-size=N
2491           This option allows finer control of linker branch stub creation.
2492           It sets the maximum size of a group of input sections that can be
2493           handled by one stub section.  A negative value of N locates stub
2494           sections after their branches, while a positive value allows stub
2495           sections to appear either before or after the branches.  Values of
2496           1 or -1 indicate that the linker should choose suitable defaults.
2497
2498       The 68HC11 and 68HC12 linkers support specific options to control the
2499       memory bank switching mapping and trampoline code generation.
2500
2501       --no-trampoline
2502           This option disables the generation of trampoline. By default a
2503           trampoline is generated for each far function which is called using
2504           a "jsr" instruction (this happens when a pointer to a far function
2505           is taken).
2506
2507       --bank-window name
2508           This option indicates to the linker the name of the memory region
2509           in the MEMORY specification that describes the memory bank window.
2510           The definition of such region is then used by the linker to compute
2511           paging and addresses within the memory window.
2512
2513       The following options are supported to control handling of GOT
2514       generation when linking for 68K targets.
2515
2516       --got=type
2517           This option tells the linker which GOT generation scheme to use.
2518           type should be one of single, negative, multigot or target.  For
2519           more information refer to the Info entry for ld.
2520
2521       The following options are supported to control microMIPS instruction
2522       generation and branch relocation checks for ISA mode transitions when
2523       linking for MIPS targets.
2524
2525       --insn32
2526       --no-insn32
2527           These options control the choice of microMIPS instructions used in
2528           code generated by the linker, such as that in the PLT or lazy
2529           binding stubs, or in relaxation.  If --insn32 is used, then the
2530           linker only uses 32-bit instruction encodings.  By default or if
2531           --no-insn32 is used, all instruction encodings are used, including
2532           16-bit ones where possible.
2533
2534       --ignore-branch-isa
2535       --no-ignore-branch-isa
2536           These options control branch relocation checks for invalid ISA mode
2537           transitions.  If --ignore-branch-isa is used, then the linker
2538           accepts any branch relocations and any ISA mode transition required
2539           is lost in relocation calculation, except for some cases of "BAL"
2540           instructions which meet relaxation conditions and are converted to
2541           equivalent "JALX" instructions as the associated relocation is
2542           calculated.  By default or if --no-ignore-branch-isa is used a
2543           check is made causing the loss of an ISA mode transition to produce
2544           an error.
2545
2546       --compact-branches
2547       --no-compact-branches
2548           These options control the generation of compact instructions by the
2549           linker in the PLT entries for MIPS R6.
2550
2551       For the pdp11-aout target, three variants of the output format can be
2552       produced as selected by the following options.  The default variant for
2553       pdp11-aout is the --omagic option, whereas for other targets --nmagic
2554       is the default.  The --imagic option is defined only for the pdp11-aout
2555       target, while the others are described here as they apply to the
2556       pdp11-aout target.
2557
2558       -N
2559       --omagic
2560           Mark the output as "OMAGIC" (0407) in the a.out header to indicate
2561           that the text segment is not to be write-protected and shared.
2562           Since the text and data sections are both readable and writable,
2563           the data section is allocated immediately contiguous after the text
2564           segment.  This is the oldest format for PDP11 executable programs
2565           and is the default for ld on PDP11 Unix systems from the beginning
2566           through 2.11BSD.
2567
2568       -n
2569       --nmagic
2570           Mark the output as "NMAGIC" (0410) in the a.out header to indicate
2571           that when the output file is executed, the text portion will be
2572           read-only and shareable among all processes executing the same
2573           file.  This involves moving the data areas up to the first possible
2574           8K byte page boundary following the end of the text.  This option
2575           creates a pure executable format.
2576
2577       -z
2578       --imagic
2579           Mark the output as "IMAGIC" (0411) in the a.out header to indicate
2580           that when the output file is executed, the program text and data
2581           areas will be loaded into separate address spaces using the split
2582           instruction and data space feature of the memory management unit in
2583           larger models of the PDP11.  This doubles the address space
2584           available to the program.  The text segment is again pure, write-
2585           protected, and shareable.  The only difference in the output format
2586           between this option and the others, besides the magic number, is
2587           that both the text and data sections start at location 0.  The -z
2588           option selected this format in 2.11BSD.  This option creates a
2589           separate executable format.
2590
2591       --no-omagic
2592           Equivalent to --nmagic for pdp11-aout.
2593

ENVIRONMENT

2595       You can change the behaviour of ld with the environment variables
2596       "GNUTARGET", "LDEMULATION" and "COLLECT_NO_DEMANGLE".
2597
2598       "GNUTARGET" determines the input-file object format if you don't use -b
2599       (or its synonym --format).  Its value should be one of the BFD names
2600       for an input format.  If there is no "GNUTARGET" in the environment, ld
2601       uses the natural format of the target. If "GNUTARGET" is set to
2602       "default" then BFD attempts to discover the input format by examining
2603       binary input files; this method often succeeds, but there are potential
2604       ambiguities, since there is no method of ensuring that the magic number
2605       used to specify object-file formats is unique.  However, the
2606       configuration procedure for BFD on each system places the conventional
2607       format for that system first in the search-list, so ambiguities are
2608       resolved in favor of convention.
2609
2610       "LDEMULATION" determines the default emulation if you don't use the -m
2611       option.  The emulation can affect various aspects of linker behaviour,
2612       particularly the default linker script.  You can list the available
2613       emulations with the --verbose or -V options.  If the -m option is not
2614       used, and the "LDEMULATION" environment variable is not defined, the
2615       default emulation depends upon how the linker was configured.
2616
2617       Normally, the linker will default to demangling symbols.  However, if
2618       "COLLECT_NO_DEMANGLE" is set in the environment, then it will default
2619       to not demangling symbols.  This environment variable is used in a
2620       similar fashion by the "gcc" linker wrapper program.  The default may
2621       be overridden by the --demangle and --no-demangle options.
2622

SEE ALSO

2624       ar(1), nm(1), objcopy(1), objdump(1), readelf(1) and the Info entries
2625       for binutils and ld.
2626
2628       Copyright (c) 1991-2020 Free Software Foundation, Inc.
2629
2630       Permission is granted to copy, distribute and/or modify this document
2631       under the terms of the GNU Free Documentation License, Version 1.3 or
2632       any later version published by the Free Software Foundation; with no
2633       Invariant Sections, with no Front-Cover Texts, and with no Back-Cover
2634       Texts.  A copy of the license is included in the section entitled "GNU
2635       Free Documentation License".
2636
2637
2638
2639binutils-2.35.1                   2021-01-26                             LD(1)
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