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

NAME

6       ld - The GNU linker
7

SYNOPSIS

9       ld [options] objfile ...
10

DESCRIPTION

12       ld combines a number of object and archive files, relocates their data
13       and ties up symbol references. Usually the last step in compiling a
14       program is to run ld.
15
16       ld accepts Linker Command Language files written in a superset of
17       AT&T's Link Editor Command Language syntax, to provide explicit and
18       total control over the linking process.
19
20       This man page does not describe the command language; see the ld entry
21       in "info" for full details on the command language and on other aspects
22       of the GNU linker.
23
24       This version of ld uses the general purpose BFD libraries to operate on
25       object files. This allows ld to read, combine, and write object files
26       in many different formats---for example, COFF or "a.out".  Different
27       formats may be linked together to produce any available kind of object
28       file.
29
30       Aside from its flexibility, the GNU linker is more helpful than other
31       linkers in providing diagnostic information.  Many linkers abandon
32       execution immediately upon encountering an error; whenever possible, ld
33       continues executing, allowing you to identify other errors (or, in some
34       cases, to get an output file in spite of the error).
35
36       The GNU linker ld is meant to cover a broad range of situations, and to
37       be as compatible as possible with other linkers.  As a result, you have
38       many choices to control its behavior.
39

OPTIONS

41       The linker supports a plethora of command-line options, but in actual
42       practice few of them are used in any particular context.  For instance,
43       a frequent use of ld is to link standard Unix object files on a
44       standard, supported Unix system.  On such a system, to link a file
45       "hello.o":
46
47               ld -o <output> /lib/crt0.o hello.o -lc
48
49       This tells ld to produce a file called output as the result of linking
50       the file "/lib/crt0.o" with "hello.o" and the library "libc.a", which
51       will come from the standard search directories.  (See the discussion of
52       the -l option below.)
53
54       Some of the command-line options to ld may be specified at any point in
55       the command line.  However, options which refer to files, such as -l or
56       -T, cause the file to be read at the point at which the option appears
57       in the command line, relative to the object files and other file
58       options.  Repeating non-file options with a different argument will
59       either have no further effect, or override prior occurrences (those
60       further to the left on the command line) of that option.  Options which
61       may be meaningfully specified more than once are noted in the
62       descriptions below.
63
64       Non-option arguments are object files or archives which are to be
65       linked together.  They may follow, precede, or be mixed in with
66       command-line options, except that an object file argument may not be
67       placed between an option and its argument.
68
69       Usually the linker is invoked with at least one object file, but you
70       can specify other forms of binary input files using -l, -R, and the
71       script command language.  If no binary input files at all are
72       specified, the linker does not produce any output, and issues the
73       message No input files.
74
75       If the linker cannot recognize the format of an object file, it will
76       assume that it is a linker script.  A script specified in this way
77       augments the main linker script used for the link (either the default
78       linker script or the one specified by using -T).  This feature permits
79       the linker to link against a file which appears to be an object or an
80       archive, but actually merely defines some symbol values, or uses
81       "INPUT" or "GROUP" to load other objects.  Specifying a script in this
82       way merely augments the main linker script, with the extra commands
83       placed after the main script; use the -T option to replace the default
84       linker script entirely, but note the effect of the "INSERT" command.
85
86       For options whose names are a single letter, option arguments must
87       either follow the option letter without intervening whitespace, or be
88       given as separate arguments immediately following the option that
89       requires them.
90
91       For options whose names are multiple letters, either one dash or two
92       can precede the option name; for example, -trace-symbol and
93       --trace-symbol are equivalent.  Note---there is one exception to this
94       rule.  Multiple letter options that start with a lower case 'o' can
95       only be preceded by two dashes.  This is to reduce confusion with the
96       -o option.  So for example -omagic sets the output file name to magic
97       whereas --omagic sets the NMAGIC flag on the output.
98
99       Arguments to multiple-letter options must either be separated from the
100       option name by an equals sign, or be given as separate arguments
101       immediately following the option that requires them.  For example,
102       --trace-symbol foo and --trace-symbol=foo are equivalent.  Unique
103       abbreviations of the names of multiple-letter options are accepted.
104
105       Note---if the linker is being invoked indirectly, via a compiler driver
106       (e.g. gcc) then all the linker command line options should be prefixed
107       by -Wl, (or whatever is appropriate for the particular compiler driver)
108       like this:
109
110                 gcc -Wl,--start-group foo.o bar.o -Wl,--end-group
111
112       This is important, because otherwise the compiler driver program may
113       silently drop the linker options, resulting in a bad link.  Confusion
114       may also arise when passing options that require values through a
115       driver, as the use of a space between option and argument acts as a
116       separator, and causes the driver to pass only the option to the linker
117       and the argument to the compiler.  In this case, it is simplest to use
118       the joined forms of both single- and multiple-letter options, such as:
119
120                 gcc foo.o bar.o -Wl,-eENTRY -Wl,-Map=a.map
121
122       Here is a table of the generic command line switches accepted by the
123       GNU linker:
124
125       @file
126           Read command-line options from file.  The options read are inserted
127           in place of the original @file option.  If file does not exist, or
128           cannot be read, then the option will be treated literally, and not
129           removed.
130
131           Options in file are separated by whitespace.  A whitespace
132           character may be included in an option by surrounding the entire
133           option in either single or double quotes.  Any character (including
134           a backslash) may be included by prefixing the character to be
135           included with a backslash.  The file may itself contain additional
136           @file options; any such options will be processed recursively.
137
138       -a keyword
139           This option is supported for HP/UX compatibility.  The keyword
140           argument must be one of the strings archive, shared, or default.
141           -aarchive is functionally equivalent to -Bstatic, and the other two
142           keywords are functionally equivalent to -Bdynamic.  This option may
143           be used any number of times.
144
145       --audit AUDITLIB
146           Adds AUDITLIB to the "DT_AUDIT" entry of the dynamic section.
147           AUDITLIB is not checked for existence, nor will it use the
148           DT_SONAME specified in the library.  If specified multiple times
149           "DT_AUDIT" will contain a colon separated list of audit interfaces
150           to use. If the linker finds an object with an audit entry while
151           searching for shared libraries, it will add a corresponding
152           "DT_DEPAUDIT" entry in the output file.  This option is only
153           meaningful on ELF platforms supporting the rtld-audit interface.
154
155       -A architecture
156       --architecture=architecture
157           In the current release of ld, this option is useful only for the
158           Intel 960 family of architectures.  In that ld configuration, the
159           architecture argument identifies the particular architecture in the
160           960 family, enabling some safeguards and modifying the archive-
161           library search path.
162
163           Future releases of ld may support similar functionality for other
164           architecture families.
165
166       -b input-format
167       --format=input-format
168           ld may be configured to support more than one kind of object file.
169           If your ld is configured this way, you can use the -b option to
170           specify the binary format for input object files that follow this
171           option on the command line.  Even when ld is configured to support
172           alternative object formats, you don't usually need to specify this,
173           as ld should be configured to expect as a default input format the
174           most usual format on each machine.  input-format is a text string,
175           the name of a particular format supported by the BFD libraries.
176           (You can list the available binary formats with objdump -i.)
177
178           You may want to use this option if you are linking files with an
179           unusual binary format.  You can also use -b to switch formats
180           explicitly (when linking object files of different formats), by
181           including -b input-format before each group of object files in a
182           particular format.
183
184           The default format is taken from the environment variable
185           "GNUTARGET".
186
187           You can also define the input format from a script, using the
188           command "TARGET";
189
190       -c MRI-commandfile
191       --mri-script=MRI-commandfile
192           For compatibility with linkers produced by MRI, ld accepts script
193           files written in an alternate, restricted command language,
194           described in the MRI Compatible Script Files section of GNU ld
195           documentation.  Introduce MRI script files with the option -c; use
196           the -T option to run linker scripts written in the general-purpose
197           ld scripting language.  If MRI-cmdfile does not exist, ld looks for
198           it in the directories specified by any -L options.
199
200       -d
201       -dc
202       -dp These three options are equivalent; multiple forms are supported
203           for compatibility with other linkers.  They assign space to common
204           symbols even if a relocatable output file is specified (with -r).
205           The script command "FORCE_COMMON_ALLOCATION" has the same effect.
206
207       --depaudit AUDITLIB
208       -P AUDITLIB
209           Adds AUDITLIB to the "DT_DEPAUDIT" entry of the dynamic section.
210           AUDITLIB is not checked for existence, nor will it use the
211           DT_SONAME specified in the library.  If specified multiple times
212           "DT_DEPAUDIT" will contain a colon separated list of audit
213           interfaces to use.  This option is only meaningful on ELF platforms
214           supporting the rtld-audit interface.  The -P option is provided for
215           Solaris compatibility.
216
217       -e entry
218       --entry=entry
219           Use entry as the explicit symbol for beginning execution of your
220           program, rather than the default entry point.  If there is no
221           symbol named entry, the linker will try to parse entry as a number,
222           and use that as the entry address (the number will be interpreted
223           in base 10; you may use a leading 0x for base 16, or a leading 0
224           for base 8).
225
226       --exclude-libs lib,lib,...
227           Specifies a list of archive libraries from which symbols should not
228           be automatically exported.  The library names may be delimited by
229           commas or colons.  Specifying "--exclude-libs ALL" excludes symbols
230           in all archive libraries from automatic export.  This option is
231           available only for the i386 PE targeted port of the linker and for
232           ELF targeted ports.  For i386 PE, symbols explicitly listed in a
233           .def file are still exported, regardless of this option.  For ELF
234           targeted ports, symbols affected by this option will be treated as
235           hidden.
236
237       --exclude-modules-for-implib module,module,...
238           Specifies a list of object files or archive members, from which
239           symbols should not be automatically exported, but which should be
240           copied wholesale into the import library being generated during the
241           link.  The module names may be delimited by commas or colons, and
242           must match exactly the filenames used by ld to open the files; for
243           archive members, this is simply the member name, but for object
244           files the name listed must include and match precisely any path
245           used to specify the input file on the linker's command-line.  This
246           option is available only for the i386 PE targeted port of the
247           linker.  Symbols explicitly listed in a .def file are still
248           exported, regardless of this option.
249
250       -E
251       --export-dynamic
252       --no-export-dynamic
253           When creating a dynamically linked executable, using the -E option
254           or the --export-dynamic option causes the linker to add all symbols
255           to the dynamic symbol table.  The dynamic symbol table is the set
256           of symbols which are visible from dynamic objects at run time.
257
258           If you do not use either of these options (or use the
259           --no-export-dynamic option to restore the default behavior), the
260           dynamic symbol table will normally contain only those symbols which
261           are referenced by some dynamic object mentioned in the link.
262
263           If you use "dlopen" to load a dynamic object which needs to refer
264           back to the symbols defined by the program, rather than some other
265           dynamic object, then you will probably need to use this option when
266           linking the program itself.
267
268           You can also use the dynamic list to control what symbols should be
269           added to the dynamic symbol table if the output format supports it.
270           See the description of --dynamic-list.
271
272           Note that this option is specific to ELF targeted ports.  PE
273           targets support a similar function to export all symbols from a DLL
274           or EXE; see the description of --export-all-symbols below.
275
276       -EB Link big-endian objects.  This affects the default output format.
277
278       -EL Link little-endian objects.  This affects the default output
279           format.
280
281       -f name
282       --auxiliary=name
283           When creating an ELF shared object, set the internal DT_AUXILIARY
284           field to the specified name.  This tells the dynamic linker that
285           the symbol table of the shared object should be used as an
286           auxiliary filter on the symbol table of the shared object name.
287
288           If you later link a program against this filter object, then, when
289           you run the program, the dynamic linker will see the DT_AUXILIARY
290           field.  If the dynamic linker resolves any symbols from the filter
291           object, it will first check whether there is a definition in the
292           shared object name.  If there is one, it will be used instead of
293           the definition in the filter object.  The shared object name need
294           not exist.  Thus the shared object name may be used to provide an
295           alternative implementation of certain functions, perhaps for
296           debugging or for machine specific performance.
297
298           This option may be specified more than once.  The DT_AUXILIARY
299           entries will be created in the order in which they appear on the
300           command line.
301
302       -F name
303       --filter=name
304           When creating an ELF shared object, set the internal DT_FILTER
305           field to the specified name.  This tells the dynamic linker that
306           the symbol table of the shared object which is being created should
307           be used as a filter on the symbol table of the shared object name.
308
309           If you later link a program against this filter object, then, when
310           you run the program, the dynamic linker will see the DT_FILTER
311           field.  The dynamic linker will resolve symbols according to the
312           symbol table of the filter object as usual, but it will actually
313           link to the definitions found in the shared object name.  Thus the
314           filter object can be used to select a subset of the symbols
315           provided by the object name.
316
317           Some older linkers used the -F option throughout a compilation
318           toolchain for specifying object-file format for both input and
319           output object files.  The GNU linker uses other mechanisms for this
320           purpose: the -b, --format, --oformat options, the "TARGET" command
321           in linker scripts, and the "GNUTARGET" environment variable.  The
322           GNU linker will ignore the -F option when not creating an ELF
323           shared object.
324
325       -fini=name
326           When creating an ELF executable or shared object, call NAME when
327           the executable or shared object is unloaded, by setting DT_FINI to
328           the address of the function.  By default, the linker uses "_fini"
329           as the function to call.
330
331       -g  Ignored.  Provided for compatibility with other tools.
332
333       -G value
334       --gpsize=value
335           Set the maximum size of objects to be optimized using the GP
336           register to size.  This is only meaningful for object file formats
337           such as MIPS ELF that support putting large and small objects into
338           different sections.  This is ignored for other object file formats.
339
340       -h name
341       -soname=name
342           When creating an ELF shared object, set the internal DT_SONAME
343           field to the specified name.  When an executable is linked with a
344           shared object which has a DT_SONAME field, then when the executable
345           is run the dynamic linker will attempt to load the shared object
346           specified by the DT_SONAME field rather than the using the file
347           name given to the linker.
348
349       -i  Perform an incremental link (same as option -r).
350
351       -init=name
352           When creating an ELF executable or shared object, call NAME when
353           the executable or shared object is loaded, by setting DT_INIT to
354           the address of the function.  By default, the linker uses "_init"
355           as the function to call.
356
357       -l namespec
358       --library=namespec
359           Add the archive or object file specified by namespec to the list of
360           files to link.  This option may be used any number of times.  If
361           namespec is of the form :filename, ld will search the library path
362           for a file called filename, otherwise it will search the library
363           path for a file called libnamespec.a.
364
365           On systems which support shared libraries, ld may also search for
366           files other than libnamespec.a.  Specifically, on ELF and SunOS
367           systems, ld will search a directory for a library called
368           libnamespec.so before searching for one called libnamespec.a.  (By
369           convention, a ".so" extension indicates a shared library.)  Note
370           that this behavior does not apply to :filename, which always
371           specifies a file called filename.
372
373           The linker will search an archive only once, at the location where
374           it is specified on the command line.  If the archive defines a
375           symbol which was undefined in some object which appeared before the
376           archive on the command line, the linker will include the
377           appropriate file(s) from the archive.  However, an undefined symbol
378           in an object appearing later on the command line will not cause the
379           linker to search the archive again.
380
381           See the -( option for a way to force the linker to search archives
382           multiple times.
383
384           You may list the same archive multiple times on the command line.
385
386           This type of archive searching is standard for Unix linkers.
387           However, if you are using ld on AIX, note that it is different from
388           the behaviour of the AIX linker.
389
390       -L searchdir
391       --library-path=searchdir
392           Add path searchdir to the list of paths that ld will search for
393           archive libraries and ld control scripts.  You may use this option
394           any number of times.  The directories are searched in the order in
395           which they are specified on the command line.  Directories
396           specified on the command line are searched before the default
397           directories.  All -L options apply to all -l options, regardless of
398           the order in which the options appear.  -L options do not affect
399           how ld searches for a linker script unless -T option is specified.
400
401           If searchdir begins with "=", then the "=" will be replaced by the
402           sysroot prefix, a path specified when the linker is configured.
403
404           The default set of paths searched (without being specified with -L)
405           depends on which emulation mode ld is using, and in some cases also
406           on how it was configured.
407
408           The paths can also be specified in a link script with the
409           "SEARCH_DIR" command.  Directories specified this way are searched
410           at the point in which the linker script appears in the command
411           line.
412
413       -m emulation
414           Emulate the emulation linker.  You can list the available
415           emulations with the --verbose or -V options.
416
417           If the -m option is not used, the emulation is taken from the
418           "LDEMULATION" environment variable, if that is defined.
419
420           Otherwise, the default emulation depends upon how the linker was
421           configured.
422
423       -M
424       --print-map
425           Print a link map to the standard output.  A link map provides
426           information about the link, including the following:
427
428           ·   Where object files are mapped into memory.
429
430           ·   How common symbols are allocated.
431
432           ·   All archive members included in the link, with a mention of the
433               symbol which caused the archive member to be brought in.
434
435           ·   The values assigned to symbols.
436
437               Note - symbols whose values are computed by an expression which
438               involves a reference to a previous value of the same symbol may
439               not have correct result displayed in the link map.  This is
440               because the linker discards intermediate results and only
441               retains the final value of an expression.  Under such
442               circumstances the linker will display the final value enclosed
443               by square brackets.  Thus for example a linker script
444               containing:
445
446                          foo = 1
447                          foo = foo * 4
448                          foo = foo + 8
449
450               will produce the following output in the link map if the -M
451               option is used:
452
453                          0x00000001                foo = 0x1
454                          [0x0000000c]                foo = (foo * 0x4)
455                          [0x0000000c]                foo = (foo + 0x8)
456
457               See Expressions for more information about expressions in
458               linker scripts.
459
460       -n
461       --nmagic
462           Turn off page alignment of sections, and disable linking against
463           shared libraries.  If the output format supports Unix style magic
464           numbers, mark the output as "NMAGIC".
465
466       -N
467       --omagic
468           Set the text and data sections to be readable and writable.  Also,
469           do not page-align the data segment, and disable linking against
470           shared libraries.  If the output format supports Unix style magic
471           numbers, mark the output as "OMAGIC". Note: Although a writable
472           text section is allowed for PE-COFF targets, it does not conform to
473           the format specification published by Microsoft.
474
475       --no-omagic
476           This option negates most of the effects of the -N option.  It sets
477           the text section to be read-only, and forces the data segment to be
478           page-aligned.  Note - this option does not enable linking against
479           shared libraries.  Use -Bdynamic for this.
480
481       -o output
482       --output=output
483           Use output as the name for the program produced by ld; if this
484           option is not specified, the name a.out is used by default.  The
485           script command "OUTPUT" can also specify the output file name.
486
487       -O level
488           If level is a numeric values greater than zero ld optimizes the
489           output.  This might take significantly longer and therefore
490           probably should only be enabled for the final binary.  At the
491           moment this option only affects ELF shared library generation.
492           Future releases of the linker may make more use of this option.
493           Also currently there is no difference in the linker's behaviour for
494           different non-zero values of this option.  Again this may change
495           with future releases.
496
497       -q
498       --emit-relocs
499           Leave relocation sections and contents in fully linked executables.
500           Post link analysis and optimization tools may need this information
501           in order to perform correct modifications of executables.  This
502           results in larger executables.
503
504           This option is currently only supported on ELF platforms.
505
506       --force-dynamic
507           Force the output file to have dynamic sections.  This option is
508           specific to VxWorks targets.
509
510       -r
511       --relocatable
512           Generate relocatable output---i.e., generate an output file that
513           can in turn serve as input to ld.  This is often called partial
514           linking.  As a side effect, in environments that support standard
515           Unix magic numbers, this option also sets the output file's magic
516           number to "OMAGIC".  If this option is not specified, an absolute
517           file is produced.  When linking C++ programs, this option will not
518           resolve references to constructors; to do that, use -Ur.
519
520           When an input file does not have the same format as the output
521           file, partial linking is only supported if that input file does not
522           contain any relocations.  Different output formats can have further
523           restrictions; for example some "a.out"-based formats do not support
524           partial linking with input files in other formats at all.
525
526           This option does the same thing as -i.
527
528       -R filename
529       --just-symbols=filename
530           Read symbol names and their addresses from filename, but do not
531           relocate it or include it in the output.  This allows your output
532           file to refer symbolically to absolute locations of memory defined
533           in other programs.  You may use this option more than once.
534
535           For compatibility with other ELF linkers, if the -R option is
536           followed by a directory name, rather than a file name, it is
537           treated as the -rpath option.
538
539       -s
540       --strip-all
541           Omit all symbol information from the output file.
542
543       -S
544       --strip-debug
545           Omit debugger symbol information (but not all symbols) from the
546           output file.
547
548       -t
549       --trace
550           Print the names of the input files as ld processes them.
551
552       -T scriptfile
553       --script=scriptfile
554           Use scriptfile as the linker script.  This script replaces ld's
555           default linker script (rather than adding to it), so commandfile
556           must specify everything necessary to describe the output file.
557           If scriptfile does not exist in the current directory, "ld" looks
558           for it in the directories specified by any preceding -L options.
559           Multiple -T options accumulate.
560
561       -dT scriptfile
562       --default-script=scriptfile
563           Use scriptfile as the default linker script.
564
565           This option is similar to the --script option except that
566           processing of the script is delayed until after the rest of the
567           command line has been processed.  This allows options placed after
568           the --default-script option on the command line to affect the
569           behaviour of the linker script, which can be important when the
570           linker command line cannot be directly controlled by the user.  (eg
571           because the command line is being constructed by another tool, such
572           as gcc).
573
574       -u symbol
575       --undefined=symbol
576           Force symbol to be entered in the output file as an undefined
577           symbol.  Doing this may, for example, trigger linking of additional
578           modules from standard libraries.  -u may be repeated with different
579           option arguments to enter additional undefined symbols.  This
580           option is equivalent to the "EXTERN" linker script command.
581
582       -Ur For anything other than C++ programs, this option is equivalent to
583           -r: it generates relocatable output---i.e., an output file that can
584           in turn serve as input to ld.  When linking C++ programs, -Ur does
585           resolve references to constructors, unlike -r.  It does not work to
586           use -Ur on files that were themselves linked with -Ur; once the
587           constructor table has been built, it cannot be added to.  Use -Ur
588           only for the last partial link, and -r for the others.
589
590       --unique[=SECTION]
591           Creates a separate output section for every input section matching
592           SECTION, or if the optional wildcard SECTION argument is missing,
593           for every orphan input section.  An orphan section is one not
594           specifically mentioned in a linker script.  You may use this option
595           multiple times on the command line;  It prevents the normal merging
596           of input sections with the same name, overriding output section
597           assignments in a linker script.
598
599       -v
600       --version
601       -V  Display the version number for ld.  The -V option also lists the
602           supported emulations.
603
604       -x
605       --discard-all
606           Delete all local symbols.
607
608       -X
609       --discard-locals
610           Delete all temporary local symbols.  (These symbols start with
611           system-specific local label prefixes, typically .L for ELF systems
612           or L for traditional a.out systems.)
613
614       -y symbol
615       --trace-symbol=symbol
616           Print the name of each linked file in which symbol appears.  This
617           option may be given any number of times.  On many systems it is
618           necessary to prepend an underscore.
619
620           This option is useful when you have an undefined symbol in your
621           link but don't know where the reference is coming from.
622
623       -Y path
624           Add path to the default library search path.  This option exists
625           for Solaris compatibility.
626
627       -z keyword
628           The recognized keywords are:
629
630           combreloc
631               Combines multiple reloc sections and sorts them to make dynamic
632               symbol lookup caching possible.
633
634           defs
635               Disallows undefined symbols in object files.  Undefined symbols
636               in shared libraries are still allowed.
637
638           execstack
639               Marks the object as requiring executable stack.
640
641           global
642               This option is only meaningful when building a shared object.
643               It makes the symbols defined by this shared object available
644               for symbol resolution of subsequently loaded libraries.
645
646           initfirst
647               This option is only meaningful when building a shared object.
648               It marks the object so that its runtime initialization will
649               occur before the runtime initialization of any other objects
650               brought into the process at the same time.  Similarly the
651               runtime finalization of the object will occur after the runtime
652               finalization of any other objects.
653
654           interpose
655               Marks the object that its symbol table interposes before all
656               symbols but the primary executable.
657
658           lazy
659               When generating an executable or shared library, mark it to
660               tell the dynamic linker to defer function call resolution to
661               the point when the function is called (lazy binding), rather
662               than at load time.  Lazy binding is the default.
663
664           loadfltr
665               Marks  the object that its filters be processed immediately at
666               runtime.
667
668           muldefs
669               Allows multiple definitions.
670
671           nocombreloc
672               Disables multiple reloc sections combining.
673
674           nocopyreloc
675               Disables production of copy relocs.
676
677           nodefaultlib
678               Marks the object that the search for dependencies of this
679               object will ignore any default library search paths.
680
681           nodelete
682               Marks the object shouldn't be unloaded at runtime.
683
684           nodlopen
685               Marks the object not available to "dlopen".
686
687           nodump
688               Marks the object can not be dumped by "dldump".
689
690           noexecstack
691               Marks the object as not requiring executable stack.
692
693           norelro
694               Don't create an ELF "PT_GNU_RELRO" segment header in the
695               object.
696
697           now When generating an executable or shared library, mark it to
698               tell the dynamic linker to resolve all symbols when the program
699               is started, or when the shared library is linked to using
700               dlopen, instead of deferring function call resolution to the
701               point when the function is first called.
702
703           origin
704               Marks the object may contain $ORIGIN.
705
706           relro
707               Create an ELF "PT_GNU_RELRO" segment header in the object.
708
709           max-page-size=value
710               Set the emulation maximum page size to value.
711
712           common-page-size=value
713               Set the emulation common page size to value.
714
715           stack-size=value
716               Specify a stack size for in an ELF "PT_GNU_STACK" segment.
717               Specifying zero will override any default non-zero sized
718               "PT_GNU_STACK" segment creation.
719
720           Other keywords are ignored for Solaris compatibility.
721
722       -( archives -)
723       --start-group archives --end-group
724           The archives should be a list of archive files.  They may be either
725           explicit file names, or -l options.
726
727           The specified archives are searched repeatedly until no new
728           undefined references are created.  Normally, an archive is searched
729           only once in the order that it is specified on the command line.
730           If a symbol in that archive is needed to resolve an undefined
731           symbol referred to by an object in an archive that appears later on
732           the command line, the linker would not be able to resolve that
733           reference.  By grouping the archives, they all be searched
734           repeatedly until all possible references are resolved.
735
736           Using this option has a significant performance cost.  It is best
737           to use it only when there are unavoidable circular references
738           between two or more archives.
739
740       --accept-unknown-input-arch
741       --no-accept-unknown-input-arch
742           Tells the linker to accept input files whose architecture cannot be
743           recognised.  The assumption is that the user knows what they are
744           doing and deliberately wants to link in these unknown input files.
745           This was the default behaviour of the linker, before release 2.14.
746           The default behaviour from release 2.14 onwards is to reject such
747           input files, and so the --accept-unknown-input-arch option has been
748           added to restore the old behaviour.
749
750       --as-needed
751       --no-as-needed
752           This option affects ELF DT_NEEDED tags for dynamic libraries
753           mentioned on the command line after the --as-needed option.
754           Normally the linker will add a DT_NEEDED tag for each dynamic
755           library mentioned on the command line, regardless of whether the
756           library is actually needed or not.  --as-needed causes a DT_NEEDED
757           tag to only be emitted for a library that at that point in the link
758           satisfies a non-weak undefined symbol reference from a regular
759           object file or, if the library is not found in the DT_NEEDED lists
760           of other libraries, a non-weak undefined symbol reference from
761           another dynamic library.  Object files or libraries appearing on
762           the command line after the library in question do not affect
763           whether the library is seen as needed.  This is similar to the
764           rules for extraction of object files from archives.  --no-as-needed
765           restores the default behaviour.
766
767       --add-needed
768       --no-add-needed
769           These two options have been deprecated because of the similarity of
770           their names to the --as-needed and --no-as-needed options.  They
771           have been replaced by --copy-dt-needed-entries and
772           --no-copy-dt-needed-entries.
773
774       -assert keyword
775           This option is ignored for SunOS compatibility.
776
777       -Bdynamic
778       -dy
779       -call_shared
780           Link against dynamic libraries.  This is only meaningful on
781           platforms for which shared libraries are supported.  This option is
782           normally the default on such platforms.  The different variants of
783           this option are for compatibility with various systems.  You may
784           use this option multiple times on the command line: it affects
785           library searching for -l options which follow it.
786
787       -Bgroup
788           Set the "DF_1_GROUP" flag in the "DT_FLAGS_1" entry in the dynamic
789           section.  This causes the runtime linker to handle lookups in this
790           object and its dependencies to be performed only inside the group.
791           --unresolved-symbols=report-all is implied.  This option is only
792           meaningful on ELF platforms which support shared libraries.
793
794       -Bstatic
795       -dn
796       -non_shared
797       -static
798           Do not link against shared libraries.  This is only meaningful on
799           platforms for which shared libraries are supported.  The different
800           variants of this option are for compatibility with various systems.
801           You may use this option multiple times on the command line: it
802           affects library searching for -l options which follow it.  This
803           option also implies --unresolved-symbols=report-all.  This option
804           can be used with -shared.  Doing so means that a shared library is
805           being created but that all of the library's external references
806           must be resolved by pulling in entries from static libraries.
807
808       -Bsymbolic
809           When creating a shared library, bind references to global symbols
810           to the definition within the shared library, if any.  Normally, it
811           is possible for a program linked against a shared library to
812           override the definition within the shared library.  This option is
813           only meaningful on ELF platforms which support shared libraries.
814
815       -Bsymbolic-functions
816           When creating a shared library, bind references to global function
817           symbols to the definition within the shared library, if any.  This
818           option is only meaningful on ELF platforms which support shared
819           libraries.
820
821       --dynamic-list=dynamic-list-file
822           Specify the name of a dynamic list file to the linker.  This is
823           typically used when creating shared libraries to specify a list of
824           global symbols whose references shouldn't be bound to the
825           definition within the shared library, or creating dynamically
826           linked executables to specify a list of symbols which should be
827           added to the symbol table in the executable.  This option is only
828           meaningful on ELF platforms which support shared libraries.
829
830           The format of the dynamic list is the same as the version node
831           without scope and node name.  See VERSION for more information.
832
833       --dynamic-list-data
834           Include all global data symbols to the dynamic list.
835
836       --dynamic-list-cpp-new
837           Provide the builtin dynamic list for C++ operator new and delete.
838           It is mainly useful for building shared libstdc++.
839
840       --dynamic-list-cpp-typeinfo
841           Provide the builtin dynamic list for C++ runtime type
842           identification.
843
844       --check-sections
845       --no-check-sections
846           Asks the linker not to check section addresses after they have been
847           assigned to see if there are any overlaps.  Normally the linker
848           will perform this check, and if it finds any overlaps it will
849           produce suitable error messages.  The linker does know about, and
850           does make allowances for sections in overlays.  The default
851           behaviour can be restored by using the command line switch
852           --check-sections.  Section overlap is not usually checked for
853           relocatable links.  You can force checking in that case by using
854           the --check-sections option.
855
856       --copy-dt-needed-entries
857       --no-copy-dt-needed-entries
858           This option affects the treatment of dynamic libraries referred to
859           by DT_NEEDED tags inside ELF dynamic libraries mentioned on the
860           command line.  Normally the linker won't add a DT_NEEDED tag to the
861           output binary for each library mentioned in a DT_NEEDED tag in an
862           input dynamic library.  With --copy-dt-needed-entries specified on
863           the command line however any dynamic libraries that follow it will
864           have their DT_NEEDED entries added.  The default behaviour can be
865           restored with --no-copy-dt-needed-entries.
866
867           This option also has an effect on the resolution of symbols in
868           dynamic libraries.  With --copy-dt-needed-entries dynamic libraries
869           mentioned on the command line will be recursively searched,
870           following their DT_NEEDED tags to other libraries, in order to
871           resolve symbols required by the output binary.  With the default
872           setting however the searching of dynamic libraries that follow it
873           will stop with the dynamic library itself.  No DT_NEEDED links will
874           be traversed to resolve symbols.
875
876       --cref
877           Output a cross reference table.  If a linker map file is being
878           generated, the cross reference table is printed to the map file.
879           Otherwise, it is printed on the standard output.
880
881           The format of the table is intentionally simple, so that it may be
882           easily processed by a script if necessary.  The symbols are printed
883           out, sorted by name.  For each symbol, a list of file names is
884           given.  If the symbol is defined, the first file listed is the
885           location of the definition.  If the symbol is defined as a common
886           value then any files where this happens appear next.  Finally any
887           files that reference the symbol are listed.
888
889       --no-define-common
890           This option inhibits the assignment of addresses to common symbols.
891           The script command "INHIBIT_COMMON_ALLOCATION" has the same effect.
892
893           The --no-define-common option allows decoupling the decision to
894           assign addresses to Common symbols from the choice of the output
895           file type; otherwise a non-Relocatable output type forces assigning
896           addresses to Common symbols.  Using --no-define-common allows
897           Common symbols that are referenced from a shared library to be
898           assigned addresses only in the main program.  This eliminates the
899           unused duplicate space in the shared library, and also prevents any
900           possible confusion over resolving to the wrong duplicate when there
901           are many dynamic modules with specialized search paths for runtime
902           symbol resolution.
903
904       --defsym=symbol=expression
905           Create a global symbol in the output file, containing the absolute
906           address given by expression.  You may use this option as many times
907           as necessary to define multiple symbols in the command line.  A
908           limited form of arithmetic is supported for the expression in this
909           context: you may give a hexadecimal constant or the name of an
910           existing symbol, or use "+" and "-" to add or subtract hexadecimal
911           constants or symbols.  If you need more elaborate expressions,
912           consider using the linker command language from a script.  Note:
913           there should be no white space between symbol, the equals sign
914           ("="), and expression.
915
916       --demangle[=style]
917       --no-demangle
918           These options control whether to demangle symbol names in error
919           messages and other output.  When the linker is told to demangle, it
920           tries to present symbol names in a readable fashion: it strips
921           leading underscores if they are used by the object file format, and
922           converts C++ mangled symbol names into user readable names.
923           Different compilers have different mangling styles.  The optional
924           demangling style argument can be used to choose an appropriate
925           demangling style for your compiler.  The linker will demangle by
926           default unless the environment variable COLLECT_NO_DEMANGLE is set.
927           These options may be used to override the default.
928
929       -Ifile
930       --dynamic-linker=file
931           Set the name of the dynamic linker.  This is only meaningful when
932           generating dynamically linked ELF executables.  The default dynamic
933           linker is normally correct; don't use this unless you know what you
934           are doing.
935
936       --fatal-warnings
937       --no-fatal-warnings
938           Treat all warnings as errors.  The default behaviour can be
939           restored with the option --no-fatal-warnings.
940
941       --force-exe-suffix
942           Make sure that an output file has a .exe suffix.
943
944           If a successfully built fully linked output file does not have a
945           ".exe" or ".dll" suffix, this option forces the linker to copy the
946           output file to one of the same name with a ".exe" suffix. This
947           option is useful when using unmodified Unix makefiles on a
948           Microsoft Windows host, since some versions of Windows won't run an
949           image unless it ends in a ".exe" suffix.
950
951       --gc-sections
952       --no-gc-sections
953           Enable garbage collection of unused input sections.  It is ignored
954           on targets that do not support this option.  The default behaviour
955           (of not performing this garbage collection) can be restored by
956           specifying --no-gc-sections on the command line.
957
958           --gc-sections decides which input sections are used by examining
959           symbols and relocations.  The section containing the entry symbol
960           and all sections containing symbols undefined on the command-line
961           will be kept, as will sections containing symbols referenced by
962           dynamic objects.  Note that when building shared libraries, the
963           linker must assume that any visible symbol is referenced.  Once
964           this initial set of sections has been determined, the linker
965           recursively marks as used any section referenced by their
966           relocations.  See --entry and --undefined.
967
968           This option can be set when doing a partial link (enabled with
969           option -r).  In this case the root of symbols kept must be
970           explicitly specified either by an --entry or --undefined option or
971           by a "ENTRY" command in the linker script.
972
973       --print-gc-sections
974       --no-print-gc-sections
975           List all sections removed by garbage collection.  The listing is
976           printed on stderr.  This option is only effective if garbage
977           collection has been enabled via the --gc-sections) option.  The
978           default behaviour (of not listing the sections that are removed)
979           can be restored by specifying --no-print-gc-sections on the command
980           line.
981
982       --print-output-format
983           Print the name of the default output format (perhaps influenced by
984           other command-line options).  This is the string that would appear
985           in an "OUTPUT_FORMAT" linker script command.
986
987       --help
988           Print a summary of the command-line options on the standard output
989           and exit.
990
991       --target-help
992           Print a summary of all target specific options on the standard
993           output and exit.
994
995       -Map=mapfile
996           Print a link map to the file mapfile.  See the description of the
997           -M option, above.
998
999       --no-keep-memory
1000           ld normally optimizes for speed over memory usage by caching the
1001           symbol tables of input files in memory.  This option tells ld to
1002           instead optimize for memory usage, by rereading the symbol tables
1003           as necessary.  This may be required if ld runs out of memory space
1004           while linking a large executable.
1005
1006       --no-undefined
1007       -z defs
1008           Report unresolved symbol references from regular object files.
1009           This is done even if the linker is creating a non-symbolic shared
1010           library.  The switch --[no-]allow-shlib-undefined controls the
1011           behaviour for reporting unresolved references found in shared
1012           libraries being linked in.
1013
1014       --allow-multiple-definition
1015       -z muldefs
1016           Normally when a symbol is defined multiple times, the linker will
1017           report a fatal error. These options allow multiple definitions and
1018           the first definition will be used.
1019
1020       --allow-shlib-undefined
1021       --no-allow-shlib-undefined
1022           Allows or disallows undefined symbols in shared libraries.  This
1023           switch is similar to --no-undefined except that it determines the
1024           behaviour when the undefined symbols are in a shared library rather
1025           than a regular object file.  It does not affect how undefined
1026           symbols in regular object files are handled.
1027
1028           The default behaviour is to report errors for any undefined symbols
1029           referenced in shared libraries if the linker is being used to
1030           create an executable, but to allow them if the linker is being used
1031           to create a shared library.
1032
1033           The reasons for allowing undefined symbol references in shared
1034           libraries specified at link time are that:
1035
1036           ·   A shared library specified at link time may not be the same as
1037               the one that is available at load time, so the symbol might
1038               actually be resolvable at load time.
1039
1040           ·   There are some operating systems, eg BeOS and HPPA, where
1041               undefined symbols in shared libraries are normal.
1042
1043               The BeOS kernel for example patches shared libraries at load
1044               time to select whichever function is most appropriate for the
1045               current architecture.  This is used, for example, to
1046               dynamically select an appropriate memset function.
1047
1048       --no-undefined-version
1049           Normally when a symbol has an undefined version, the linker will
1050           ignore it. This option disallows symbols with undefined version and
1051           a fatal error will be issued instead.
1052
1053       --default-symver
1054           Create and use a default symbol version (the soname) for
1055           unversioned exported symbols.
1056
1057       --default-imported-symver
1058           Create and use a default symbol version (the soname) for
1059           unversioned imported symbols.
1060
1061       --no-warn-mismatch
1062           Normally ld will give an error if you try to link together input
1063           files that are mismatched for some reason, perhaps because they
1064           have been compiled for different processors or for different
1065           endiannesses.  This option tells ld that it should silently permit
1066           such possible errors.  This option should only be used with care,
1067           in cases when you have taken some special action that ensures that
1068           the linker errors are inappropriate.
1069
1070       --no-warn-search-mismatch
1071           Normally ld will give a warning if it finds an incompatible library
1072           during a library search.  This option silences the warning.
1073
1074       --no-whole-archive
1075           Turn off the effect of the --whole-archive option for subsequent
1076           archive files.
1077
1078       --noinhibit-exec
1079           Retain the executable output file whenever it is still usable.
1080           Normally, the linker will not produce an output file if it
1081           encounters errors during the link process; it exits without writing
1082           an output file when it issues any error whatsoever.
1083
1084       -nostdlib
1085           Only search library directories explicitly specified on the command
1086           line.  Library directories specified in linker scripts (including
1087           linker scripts specified on the command line) are ignored.
1088
1089       --oformat=output-format
1090           ld may be configured to support more than one kind of object file.
1091           If your ld is configured this way, you can use the --oformat option
1092           to specify the binary format for the output object file.  Even when
1093           ld is configured to support alternative object formats, you don't
1094           usually need to specify this, as ld should be configured to produce
1095           as a default output format the most usual format on each machine.
1096           output-format is a text string, the name of a particular format
1097           supported by the BFD libraries.  (You can list the available binary
1098           formats with objdump -i.)  The script command "OUTPUT_FORMAT" can
1099           also specify the output format, but this option overrides it.
1100
1101       -pie
1102       --pic-executable
1103           Create a position independent executable.  This is currently only
1104           supported on ELF platforms.  Position independent executables are
1105           similar to shared libraries in that they are relocated by the
1106           dynamic linker to the virtual address the OS chooses for them
1107           (which can vary between invocations).  Like normal dynamically
1108           linked executables they can be executed and symbols defined in the
1109           executable cannot be overridden by shared libraries.
1110
1111       -qmagic
1112           This option is ignored for Linux compatibility.
1113
1114       -Qy This option is ignored for SVR4 compatibility.
1115
1116       --relax
1117       --no-relax
1118           An option with machine dependent effects.  This option is only
1119           supported on a few targets.
1120
1121           On some platforms the --relax option performs target specific,
1122           global optimizations that become possible when the linker resolves
1123           addressing in the program, such as relaxing address modes,
1124           synthesizing new instructions, selecting shorter version of current
1125           instructions, and combining constant values.
1126
1127           On some platforms these link time global optimizations may make
1128           symbolic debugging of the resulting executable impossible.  This is
1129           known to be the case for the Matsushita MN10200 and MN10300 family
1130           of processors.
1131
1132           On platforms where this is not supported, --relax is accepted, but
1133           ignored.
1134
1135           On platforms where --relax is accepted the option --no-relax can be
1136           used to disable the feature.
1137
1138       --retain-symbols-file=filename
1139           Retain only the symbols listed in the file filename, discarding all
1140           others.  filename is simply a flat file, with one symbol name per
1141           line.  This option is especially useful in environments (such as
1142           VxWorks) where a large global symbol table is accumulated
1143           gradually, to conserve run-time memory.
1144
1145           --retain-symbols-file does not discard undefined symbols, or
1146           symbols needed for relocations.
1147
1148           You may only specify --retain-symbols-file once in the command
1149           line.  It overrides -s and -S.
1150
1151       -rpath=dir
1152           Add a directory to the runtime library search path.  This is used
1153           when linking an ELF executable with shared objects.  All -rpath
1154           arguments are concatenated and passed to the runtime linker, which
1155           uses them to locate shared objects at runtime.  The -rpath option
1156           is also used when locating shared objects which are needed by
1157           shared objects explicitly included in the link; see the description
1158           of the -rpath-link option.  If -rpath is not used when linking an
1159           ELF executable, the contents of the environment variable
1160           "LD_RUN_PATH" will be used if it is defined.
1161
1162           The -rpath option may also be used on SunOS.  By default, on SunOS,
1163           the linker will form a runtime search patch out of all the -L
1164           options it is given.  If a -rpath option is used, the runtime
1165           search path will be formed exclusively using the -rpath options,
1166           ignoring the -L options.  This can be useful when using gcc, which
1167           adds many -L options which may be on NFS mounted file systems.
1168
1169           For compatibility with other ELF linkers, if the -R option is
1170           followed by a directory name, rather than a file name, it is
1171           treated as the -rpath option.
1172
1173       -rpath-link=dir
1174           When using ELF or SunOS, one shared library may require another.
1175           This happens when an "ld -shared" link includes a shared library as
1176           one of the input files.
1177
1178           When the linker encounters such a dependency when doing a non-
1179           shared, non-relocatable link, it will automatically try to locate
1180           the required shared library and include it in the link, if it is
1181           not included explicitly.  In such a case, the -rpath-link option
1182           specifies the first set of directories to search.  The -rpath-link
1183           option may specify a sequence of directory names either by
1184           specifying a list of names separated by colons, or by appearing
1185           multiple times.
1186
1187           This option should be used with caution as it overrides the search
1188           path that may have been hard compiled into a shared library. In
1189           such a case it is possible to use unintentionally a different
1190           search path than the runtime linker would do.
1191
1192           The linker uses the following search paths to locate required
1193           shared libraries:
1194
1195           1.  Any directories specified by -rpath-link options.
1196
1197           2.  Any directories specified by -rpath options.  The difference
1198               between -rpath and -rpath-link is that directories specified by
1199               -rpath options are included in the executable and used at
1200               runtime, whereas the -rpath-link option is only effective at
1201               link time. Searching -rpath in this way is only supported by
1202               native linkers and cross linkers which have been configured
1203               with the --with-sysroot option.
1204
1205           3.  On an ELF system, for native linkers, if the -rpath and
1206               -rpath-link options were not used, search the contents of the
1207               environment variable "LD_RUN_PATH".
1208
1209           4.  On SunOS, if the -rpath option was not used, search any
1210               directories specified using -L options.
1211
1212           5.  For a native linker, search the contents of the environment
1213               variable "LD_LIBRARY_PATH".
1214
1215           6.  For a native ELF linker, the directories in "DT_RUNPATH" or
1216               "DT_RPATH" of a shared library are searched for shared
1217               libraries needed by it. The "DT_RPATH" entries are ignored if
1218               "DT_RUNPATH" entries exist.
1219
1220           7.  The default directories, normally /lib and /usr/lib.
1221
1222           8.  For a native linker on an ELF system, if the file
1223               /etc/ld.so.conf exists, the list of directories found in that
1224               file.
1225
1226           If the required shared library is not found, the linker will issue
1227           a warning and continue with the link.
1228
1229       -shared
1230       -Bshareable
1231           Create a shared library.  This is currently only supported on ELF,
1232           XCOFF and SunOS platforms.  On SunOS, the linker will automatically
1233           create a shared library if the -e option is not used and there are
1234           undefined symbols in the link.
1235
1236       --sort-common
1237       --sort-common=ascending
1238       --sort-common=descending
1239           This option tells ld to sort the common symbols by alignment in
1240           ascending or descending order when it places them in the
1241           appropriate output sections.  The symbol alignments considered are
1242           sixteen-byte or larger, eight-byte, four-byte, two-byte, and one-
1243           byte. This is to prevent gaps between symbols due to alignment
1244           constraints.  If no sorting order is specified, then descending
1245           order is assumed.
1246
1247       --sort-section=name
1248           This option will apply "SORT_BY_NAME" to all wildcard section
1249           patterns in the linker script.
1250
1251       --sort-section=alignment
1252           This option will apply "SORT_BY_ALIGNMENT" to all wildcard section
1253           patterns in the linker script.
1254
1255       --split-by-file[=size]
1256           Similar to --split-by-reloc but creates a new output section for
1257           each input file when size is reached.  size defaults to a size of 1
1258           if not given.
1259
1260       --split-by-reloc[=count]
1261           Tries to creates extra sections in the output file so that no
1262           single output section in the file contains more than count
1263           relocations.  This is useful when generating huge relocatable files
1264           for downloading into certain real time kernels with the COFF object
1265           file format; since COFF cannot represent more than 65535
1266           relocations in a single section.  Note that this will fail to work
1267           with object file formats which do not support arbitrary sections.
1268           The linker will not split up individual input sections for
1269           redistribution, so if a single input section contains more than
1270           count relocations one output section will contain that many
1271           relocations.  count defaults to a value of 32768.
1272
1273       --stats
1274           Compute and display statistics about the operation of the linker,
1275           such as execution time and memory usage.
1276
1277       --sysroot=directory
1278           Use directory as the location of the sysroot, overriding the
1279           configure-time default.  This option is only supported by linkers
1280           that were configured using --with-sysroot.
1281
1282       --traditional-format
1283           For some targets, the output of ld is different in some ways from
1284           the output of some existing linker.  This switch requests ld to use
1285           the traditional format instead.
1286
1287           For example, on SunOS, ld combines duplicate entries in the symbol
1288           string table.  This can reduce the size of an output file with full
1289           debugging information by over 30 percent.  Unfortunately, the SunOS
1290           "dbx" program can not read the resulting program ("gdb" has no
1291           trouble).  The --traditional-format switch tells ld to not combine
1292           duplicate entries.
1293
1294       --section-start=sectionname=org
1295           Locate a section in the output file at the absolute address given
1296           by org.  You may use this option as many times as necessary to
1297           locate multiple sections in the command line.  org must be a single
1298           hexadecimal integer; for compatibility with other linkers, you may
1299           omit the leading 0x usually associated with hexadecimal values.
1300           Note: there should be no white space between sectionname, the
1301           equals sign ("="), and org.
1302
1303       -Tbss=org
1304       -Tdata=org
1305       -Ttext=org
1306           Same as --section-start, with ".bss", ".data" or ".text" as the
1307           sectionname.
1308
1309       -Ttext-segment=org
1310           When creating an ELF executable or shared object, it will set the
1311           address of the first byte of the text segment.
1312
1313       -Trodata-segment=org
1314           When creating an ELF executable or shared object for a target where
1315           the read-only data is in its own segment separate from the
1316           executable text, it will set the address of the first byte of the
1317           read-only data segment.
1318
1319       -Tldata-segment=org
1320           When creating an ELF executable or shared object for x86-64 medium
1321           memory model, it will set the address of the first byte of the
1322           ldata segment.
1323
1324       --unresolved-symbols=method
1325           Determine how to handle unresolved symbols.  There are four
1326           possible values for method:
1327
1328           ignore-all
1329               Do not report any unresolved symbols.
1330
1331           report-all
1332               Report all unresolved symbols.  This is the default.
1333
1334           ignore-in-object-files
1335               Report unresolved symbols that are contained in shared
1336               libraries, but ignore them if they come from regular object
1337               files.
1338
1339           ignore-in-shared-libs
1340               Report unresolved symbols that come from regular object files,
1341               but ignore them if they come from shared libraries.  This can
1342               be useful when creating a dynamic binary and it is known that
1343               all the shared libraries that it should be referencing are
1344               included on the linker's command line.
1345
1346           The behaviour for shared libraries on their own can also be
1347           controlled by the --[no-]allow-shlib-undefined option.
1348
1349           Normally the linker will generate an error message for each
1350           reported unresolved symbol but the option --warn-unresolved-symbols
1351           can change this to a warning.
1352
1353       --dll-verbose
1354       --verbose[=NUMBER]
1355           Display the version number for ld and list the linker emulations
1356           supported.  Display which input files can and cannot be opened.
1357           Display the linker script being used by the linker. If the optional
1358           NUMBER argument > 1, plugin symbol status will also be displayed.
1359
1360       --version-script=version-scriptfile
1361           Specify the name of a version script to the linker.  This is
1362           typically used when creating shared libraries to specify additional
1363           information about the version hierarchy for the library being
1364           created.  This option is only fully supported on ELF platforms
1365           which support shared libraries; see VERSION.  It is partially
1366           supported on PE platforms, which can use version scripts to filter
1367           symbol visibility in auto-export mode: any symbols marked local in
1368           the version script will not be exported.
1369
1370       --warn-common
1371           Warn when a common symbol is combined with another common symbol or
1372           with a symbol definition.  Unix linkers allow this somewhat sloppy
1373           practice, but linkers on some other operating systems do not.  This
1374           option allows you to find potential problems from combining global
1375           symbols.  Unfortunately, some C libraries use this practice, so you
1376           may get some warnings about symbols in the libraries as well as in
1377           your programs.
1378
1379           There are three kinds of global symbols, illustrated here by C
1380           examples:
1381
1382           int i = 1;
1383               A definition, which goes in the initialized data section of the
1384               output file.
1385
1386           extern int i;
1387               An undefined reference, which does not allocate space.  There
1388               must be either a definition or a common symbol for the variable
1389               somewhere.
1390
1391           int i;
1392               A common symbol.  If there are only (one or more) common
1393               symbols for a variable, it goes in the uninitialized data area
1394               of the output file.  The linker merges multiple common symbols
1395               for the same variable into a single symbol.  If they are of
1396               different sizes, it picks the largest size.  The linker turns a
1397               common symbol into a declaration, if there is a definition of
1398               the same variable.
1399
1400           The --warn-common option can produce five kinds of warnings.  Each
1401           warning consists of a pair of lines: the first describes the symbol
1402           just encountered, and the second describes the previous symbol
1403           encountered with the same name.  One or both of the two symbols
1404           will be a common symbol.
1405
1406           1.  Turning a common symbol into a reference, because there is
1407               already a definition for the symbol.
1408
1409                       <file>(<section>): warning: common of `<symbol>'
1410                          overridden by definition
1411                       <file>(<section>): warning: defined here
1412
1413           2.  Turning a common symbol into a reference, because a later
1414               definition for the symbol is encountered.  This is the same as
1415               the previous case, except that the symbols are encountered in a
1416               different order.
1417
1418                       <file>(<section>): warning: definition of `<symbol>'
1419                          overriding common
1420                       <file>(<section>): warning: common is here
1421
1422           3.  Merging a common symbol with a previous same-sized common
1423               symbol.
1424
1425                       <file>(<section>): warning: multiple common
1426                          of `<symbol>'
1427                       <file>(<section>): warning: previous common is here
1428
1429           4.  Merging a common symbol with a previous larger common symbol.
1430
1431                       <file>(<section>): warning: common of `<symbol>'
1432                          overridden by larger common
1433                       <file>(<section>): warning: larger common is here
1434
1435           5.  Merging a common symbol with a previous smaller common symbol.
1436               This is the same as the previous case, except that the symbols
1437               are encountered in a different order.
1438
1439                       <file>(<section>): warning: common of `<symbol>'
1440                          overriding smaller common
1441                       <file>(<section>): warning: smaller common is here
1442
1443       --warn-constructors
1444           Warn if any global constructors are used.  This is only useful for
1445           a few object file formats.  For formats like COFF or ELF, the
1446           linker can not detect the use of global constructors.
1447
1448       --warn-multiple-gp
1449           Warn if multiple global pointer values are required in the output
1450           file.  This is only meaningful for certain processors, such as the
1451           Alpha.  Specifically, some processors put large-valued constants in
1452           a special section.  A special register (the global pointer) points
1453           into the middle of this section, so that constants can be loaded
1454           efficiently via a base-register relative addressing mode.  Since
1455           the offset in base-register relative mode is fixed and relatively
1456           small (e.g., 16 bits), this limits the maximum size of the constant
1457           pool.  Thus, in large programs, it is often necessary to use
1458           multiple global pointer values in order to be able to address all
1459           possible constants.  This option causes a warning to be issued
1460           whenever this case occurs.
1461
1462       --warn-once
1463           Only warn once for each undefined symbol, rather than once per
1464           module which refers to it.
1465
1466       --warn-section-align
1467           Warn if the address of an output section is changed because of
1468           alignment.  Typically, the alignment will be set by an input
1469           section.  The address will only be changed if it not explicitly
1470           specified; that is, if the "SECTIONS" command does not specify a
1471           start address for the section.
1472
1473       --warn-shared-textrel
1474           Warn if the linker adds a DT_TEXTREL to a shared object.
1475
1476       --warn-alternate-em
1477           Warn if an object has alternate ELF machine code.
1478
1479       --warn-unresolved-symbols
1480           If the linker is going to report an unresolved symbol (see the
1481           option --unresolved-symbols) it will normally generate an error.
1482           This option makes it generate a warning instead.
1483
1484       --error-unresolved-symbols
1485           This restores the linker's default behaviour of generating errors
1486           when it is reporting unresolved symbols.
1487
1488       --whole-archive
1489           For each archive mentioned on the command line after the
1490           --whole-archive option, include every object file in the archive in
1491           the link, rather than searching the archive for the required object
1492           files.  This is normally used to turn an archive file into a shared
1493           library, forcing every object to be included in the resulting
1494           shared library.  This option may be used more than once.
1495
1496           Two notes when using this option from gcc: First, gcc doesn't know
1497           about this option, so you have to use -Wl,-whole-archive.  Second,
1498           don't forget to use -Wl,-no-whole-archive after your list of
1499           archives, because gcc will add its own list of archives to your
1500           link and you may not want this flag to affect those as well.
1501
1502       --wrap=symbol
1503           Use a wrapper function for symbol.  Any undefined reference to
1504           symbol will be resolved to "__wrap_symbol".  Any undefined
1505           reference to "__real_symbol" will be resolved to symbol.
1506
1507           This can be used to provide a wrapper for a system function.  The
1508           wrapper function should be called "__wrap_symbol".  If it wishes to
1509           call the system function, it should call "__real_symbol".
1510
1511           Here is a trivial example:
1512
1513                   void *
1514                   __wrap_malloc (size_t c)
1515                   {
1516                     printf ("malloc called with %zu\n", c);
1517                     return __real_malloc (c);
1518                   }
1519
1520           If you link other code with this file using --wrap malloc, then all
1521           calls to "malloc" will call the function "__wrap_malloc" instead.
1522           The call to "__real_malloc" in "__wrap_malloc" will call the real
1523           "malloc" function.
1524
1525           You may wish to provide a "__real_malloc" function as well, so that
1526           links without the --wrap option will succeed.  If you do this, you
1527           should not put the definition of "__real_malloc" in the same file
1528           as "__wrap_malloc"; if you do, the assembler may resolve the call
1529           before the linker has a chance to wrap it to "malloc".
1530
1531       --eh-frame-hdr
1532           Request creation of ".eh_frame_hdr" section and ELF
1533           "PT_GNU_EH_FRAME" segment header.
1534
1535       --no-ld-generated-unwind-info
1536           Request creation of ".eh_frame" unwind info for linker generated
1537           code sections like PLT.  This option is on by default if linker
1538           generated unwind info is supported.
1539
1540       --enable-new-dtags
1541       --disable-new-dtags
1542           This linker can create the new dynamic tags in ELF. But the older
1543           ELF systems may not understand them. If you specify
1544           --enable-new-dtags, the new dynamic tags will be created as needed
1545           and older dynamic tags will be omitted.  If you specify
1546           --disable-new-dtags, no new dynamic tags will be created. By
1547           default, the new dynamic tags are not created. Note that those
1548           options are only available for ELF systems.
1549
1550       --hash-size=number
1551           Set the default size of the linker's hash tables to a prime number
1552           close to number.  Increasing this value can reduce the length of
1553           time it takes the linker to perform its tasks, at the expense of
1554           increasing the linker's memory requirements.  Similarly reducing
1555           this value can reduce the memory requirements at the expense of
1556           speed.
1557
1558       --hash-style=style
1559           Set the type of linker's hash table(s).  style can be either "sysv"
1560           for classic ELF ".hash" section, "gnu" for new style GNU
1561           ".gnu.hash" section or "both" for both the classic ELF ".hash" and
1562           new style GNU ".gnu.hash" hash tables.  The default is "sysv".
1563
1564       --reduce-memory-overheads
1565           This option reduces memory requirements at ld runtime, at the
1566           expense of linking speed.  This was introduced to select the old
1567           O(n^2) algorithm for link map file generation, rather than the new
1568           O(n) algorithm which uses about 40% more memory for symbol storage.
1569
1570           Another effect of the switch is to set the default hash table size
1571           to 1021, which again saves memory at the cost of lengthening the
1572           linker's run time.  This is not done however if the --hash-size
1573           switch has been used.
1574
1575           The --reduce-memory-overheads switch may be also be used to enable
1576           other tradeoffs in future versions of the linker.
1577
1578       --build-id
1579       --build-id=style
1580           Request creation of ".note.gnu.build-id" ELF note section.  The
1581           contents of the note are unique bits identifying this linked file.
1582           style can be "uuid" to use 128 random bits, "sha1" to use a 160-bit
1583           SHA1 hash on the normative parts of the output contents, "md5" to
1584           use a 128-bit MD5 hash on the normative parts of the output
1585           contents, or "0xhexstring" to use a chosen bit string specified as
1586           an even number of hexadecimal digits ("-" and ":" characters
1587           between digit pairs are ignored).  If style is omitted, "sha1" is
1588           used.
1589
1590           The "md5" and "sha1" styles produces an identifier that is always
1591           the same in an identical output file, but will be unique among all
1592           nonidentical output files.  It is not intended to be compared as a
1593           checksum for the file's contents.  A linked file may be changed
1594           later by other tools, but the build ID bit string identifying the
1595           original linked file does not change.
1596
1597           Passing "none" for style disables the setting from any "--build-id"
1598           options earlier on the command line.
1599
1600       The i386 PE linker supports the -shared option, which causes the output
1601       to be a dynamically linked library (DLL) instead of a normal
1602       executable.  You should name the output "*.dll" when you use this
1603       option.  In addition, the linker fully supports the standard "*.def"
1604       files, which may be specified on the linker command line like an object
1605       file (in fact, it should precede archives it exports symbols from, to
1606       ensure that they get linked in, just like a normal object file).
1607
1608       In addition to the options common to all targets, the i386 PE linker
1609       support additional command line options that are specific to the i386
1610       PE target.  Options that take values may be separated from their values
1611       by either a space or an equals sign.
1612
1613       --add-stdcall-alias
1614           If given, symbols with a stdcall suffix (@nn) will be exported as-
1615           is and also with the suffix stripped.  [This option is specific to
1616           the i386 PE targeted port of the linker]
1617
1618       --base-file file
1619           Use file as the name of a file in which to save the base addresses
1620           of all the relocations needed for generating DLLs with dlltool.
1621           [This is an i386 PE specific option]
1622
1623       --dll
1624           Create a DLL instead of a regular executable.  You may also use
1625           -shared or specify a "LIBRARY" in a given ".def" file.  [This
1626           option is specific to the i386 PE targeted port of the linker]
1627
1628       --enable-long-section-names
1629       --disable-long-section-names
1630           The PE variants of the Coff object format add an extension that
1631           permits the use of section names longer than eight characters, the
1632           normal limit for Coff.  By default, these names are only allowed in
1633           object files, as fully-linked executable images do not carry the
1634           Coff string table required to support the longer names.  As a GNU
1635           extension, it is possible to allow their use in executable images
1636           as well, or to (probably pointlessly!)  disallow it in object
1637           files, by using these two options.  Executable images generated
1638           with these long section names are slightly non-standard, carrying
1639           as they do a string table, and may generate confusing output when
1640           examined with non-GNU PE-aware tools, such as file viewers and
1641           dumpers.  However, GDB relies on the use of PE long section names
1642           to find Dwarf-2 debug information sections in an executable image
1643           at runtime, and so if neither option is specified on the command-
1644           line, ld will enable long section names, overriding the default and
1645           technically correct behaviour, when it finds the presence of debug
1646           information while linking an executable image and not stripping
1647           symbols.  [This option is valid for all PE targeted ports of the
1648           linker]
1649
1650       --enable-stdcall-fixup
1651       --disable-stdcall-fixup
1652           If the link finds a symbol that it cannot resolve, it will attempt
1653           to do "fuzzy linking" by looking for another defined symbol that
1654           differs only in the format of the symbol name (cdecl vs stdcall)
1655           and will resolve that symbol by linking to the match.  For example,
1656           the undefined symbol "_foo" might be linked to the function
1657           "_foo@12", or the undefined symbol "_bar@16" might be linked to the
1658           function "_bar".  When the linker does this, it prints a warning,
1659           since it normally should have failed to link, but sometimes import
1660           libraries generated from third-party dlls may need this feature to
1661           be usable.  If you specify --enable-stdcall-fixup, this feature is
1662           fully enabled and warnings are not printed.  If you specify
1663           --disable-stdcall-fixup, this feature is disabled and such
1664           mismatches are considered to be errors.  [This option is specific
1665           to the i386 PE targeted port of the linker]
1666
1667       --leading-underscore
1668       --no-leading-underscore
1669           For most targets default symbol-prefix is an underscore and is
1670           defined in target's description. By this option it is possible to
1671           disable/enable the default underscore symbol-prefix.
1672
1673       --export-all-symbols
1674           If given, all global symbols in the objects used to build a DLL
1675           will be exported by the DLL.  Note that this is the default if
1676           there otherwise wouldn't be any exported symbols.  When symbols are
1677           explicitly exported via DEF files or implicitly exported via
1678           function attributes, the default is to not export anything else
1679           unless this option is given.  Note that the symbols "DllMain@12",
1680           "DllEntryPoint@0", "DllMainCRTStartup@12", and "impure_ptr" will
1681           not be automatically exported.  Also, symbols imported from other
1682           DLLs will not be re-exported, nor will symbols specifying the DLL's
1683           internal layout such as those beginning with "_head_" or ending
1684           with "_iname".  In addition, no symbols from "libgcc", "libstd++",
1685           "libmingw32", or "crtX.o" will be exported.  Symbols whose names
1686           begin with "__rtti_" or "__builtin_" will not be exported, to help
1687           with C++ DLLs.  Finally, there is an extensive list of cygwin-
1688           private symbols that are not exported (obviously, this applies on
1689           when building DLLs for cygwin targets).  These cygwin-excludes are:
1690           "_cygwin_dll_entry@12", "_cygwin_crt0_common@8",
1691           "_cygwin_noncygwin_dll_entry@12", "_fmode", "_impure_ptr",
1692           "cygwin_attach_dll", "cygwin_premain0", "cygwin_premain1",
1693           "cygwin_premain2", "cygwin_premain3", and "environ".  [This option
1694           is specific to the i386 PE targeted port of the linker]
1695
1696       --exclude-symbols symbol,symbol,...
1697           Specifies a list of symbols which should not be automatically
1698           exported.  The symbol names may be delimited by commas or colons.
1699           [This option is specific to the i386 PE targeted port of the
1700           linker]
1701
1702       --exclude-all-symbols
1703           Specifies no symbols should be automatically exported.  [This
1704           option is specific to the i386 PE targeted port of the linker]
1705
1706       --file-alignment
1707           Specify the file alignment.  Sections in the file will always begin
1708           at file offsets which are multiples of this number.  This defaults
1709           to 512.  [This option is specific to the i386 PE targeted port of
1710           the linker]
1711
1712       --heap reserve
1713       --heap reserve,commit
1714           Specify the number of bytes of memory to reserve (and optionally
1715           commit) to be used as heap for this program.  The default is 1MB
1716           reserved, 4K committed.  [This option is specific to the i386 PE
1717           targeted port of the linker]
1718
1719       --image-base value
1720           Use value as the base address of your program or dll.  This is the
1721           lowest memory location that will be used when your program or dll
1722           is loaded.  To reduce the need to relocate and improve performance
1723           of your dlls, each should have a unique base address and not
1724           overlap any other dlls.  The default is 0x400000 for executables,
1725           and 0x10000000 for dlls.  [This option is specific to the i386 PE
1726           targeted port of the linker]
1727
1728       --kill-at
1729           If given, the stdcall suffixes (@nn) will be stripped from symbols
1730           before they are exported.  [This option is specific to the i386 PE
1731           targeted port of the linker]
1732
1733       --large-address-aware
1734           If given, the appropriate bit in the "Characteristics" field of the
1735           COFF header is set to indicate that this executable supports
1736           virtual addresses greater than 2 gigabytes.  This should be used in
1737           conjunction with the /3GB or /USERVA=value megabytes switch in the
1738           "[operating systems]" section of the BOOT.INI.  Otherwise, this bit
1739           has no effect.  [This option is specific to PE targeted ports of
1740           the linker]
1741
1742       --disable-large-address-aware
1743           Reverts the effect of a previous --large-address-aware option.
1744           This is useful if --large-address-aware is always set by the
1745           compiler driver (e.g. Cygwin gcc) and the executable does not
1746           support virtual addresses greater than 2 gigabytes.  [This option
1747           is specific to PE targeted ports of the linker]
1748
1749       --major-image-version value
1750           Sets the major number of the "image version".  Defaults to 1.
1751           [This option is specific to the i386 PE targeted port of the
1752           linker]
1753
1754       --major-os-version value
1755           Sets the major number of the "os version".  Defaults to 4.  [This
1756           option is specific to the i386 PE targeted port of the linker]
1757
1758       --major-subsystem-version value
1759           Sets the major number of the "subsystem version".  Defaults to 4.
1760           [This option is specific to the i386 PE targeted port of the
1761           linker]
1762
1763       --minor-image-version value
1764           Sets the minor number of the "image version".  Defaults to 0.
1765           [This option is specific to the i386 PE targeted port of the
1766           linker]
1767
1768       --minor-os-version value
1769           Sets the minor number of the "os version".  Defaults to 0.  [This
1770           option is specific to the i386 PE targeted port of the linker]
1771
1772       --minor-subsystem-version value
1773           Sets the minor number of the "subsystem version".  Defaults to 0.
1774           [This option is specific to the i386 PE targeted port of the
1775           linker]
1776
1777       --output-def file
1778           The linker will create the file file which will contain a DEF file
1779           corresponding to the DLL the linker is generating.  This DEF file
1780           (which should be called "*.def") may be used to create an import
1781           library with "dlltool" or may be used as a reference to
1782           automatically or implicitly exported symbols.  [This option is
1783           specific to the i386 PE targeted port of the linker]
1784
1785       --out-implib file
1786           The linker will create the file file which will contain an import
1787           lib corresponding to the DLL the linker is generating. This import
1788           lib (which should be called "*.dll.a" or "*.a" may be used to link
1789           clients against the generated DLL; this behaviour makes it possible
1790           to skip a separate "dlltool" import library creation step.  [This
1791           option is specific to the i386 PE targeted port of the linker]
1792
1793       --enable-auto-image-base
1794           Automatically choose the image base for DLLs, unless one is
1795           specified using the "--image-base" argument.  By using a hash
1796           generated from the dllname to create unique image bases for each
1797           DLL, in-memory collisions and relocations which can delay program
1798           execution are avoided.  [This option is specific to the i386 PE
1799           targeted port of the linker]
1800
1801       --disable-auto-image-base
1802           Do not automatically generate a unique image base.  If there is no
1803           user-specified image base ("--image-base") then use the platform
1804           default.  [This option is specific to the i386 PE targeted port of
1805           the linker]
1806
1807       --dll-search-prefix string
1808           When linking dynamically to a dll without an import library, search
1809           for "<string><basename>.dll" in preference to "lib<basename>.dll".
1810           This behaviour allows easy distinction between DLLs built for the
1811           various "subplatforms": native, cygwin, uwin, pw, etc.  For
1812           instance, cygwin DLLs typically use "--dll-search-prefix=cyg".
1813           [This option is specific to the i386 PE targeted port of the
1814           linker]
1815
1816       --enable-auto-import
1817           Do sophisticated linking of "_symbol" to "__imp__symbol" for DATA
1818           imports from DLLs, and create the necessary thunking symbols when
1819           building the import libraries with those DATA exports. Note: Use of
1820           the 'auto-import' extension will cause the text section of the
1821           image file to be made writable. This does not conform to the PE-
1822           COFF format specification published by Microsoft.
1823
1824           Note - use of the 'auto-import' extension will also cause read only
1825           data which would normally be placed into the .rdata section to be
1826           placed into the .data section instead.  This is in order to work
1827           around a problem with consts that is described here:
1828           http://www.cygwin.com/ml/cygwin/2004-09/msg01101.html
1829
1830           Using 'auto-import' generally will 'just work' -- but sometimes you
1831           may see this message:
1832
1833           "variable '<var>' can't be auto-imported. Please read the
1834           documentation for ld's "--enable-auto-import" for details."
1835
1836           This message occurs when some (sub)expression accesses an address
1837           ultimately given by the sum of two constants (Win32 import tables
1838           only allow one).  Instances where this may occur include accesses
1839           to member fields of struct variables imported from a DLL, as well
1840           as using a constant index into an array variable imported from a
1841           DLL.  Any multiword variable (arrays, structs, long long, etc) may
1842           trigger this error condition.  However, regardless of the exact
1843           data type of the offending exported variable, ld will always detect
1844           it, issue the warning, and exit.
1845
1846           There are several ways to address this difficulty, regardless of
1847           the data type of the exported variable:
1848
1849           One way is to use --enable-runtime-pseudo-reloc switch. This leaves
1850           the task of adjusting references in your client code for runtime
1851           environment, so this method works only when runtime environment
1852           supports this feature.
1853
1854           A second solution is to force one of the 'constants' to be a
1855           variable -- that is, unknown and un-optimizable at compile time.
1856           For arrays, there are two possibilities: a) make the indexee (the
1857           array's address) a variable, or b) make the 'constant' index a
1858           variable.  Thus:
1859
1860                   extern type extern_array[];
1861                   extern_array[1] -->
1862                      { volatile type *t=extern_array; t[1] }
1863
1864           or
1865
1866                   extern type extern_array[];
1867                   extern_array[1] -->
1868                      { volatile int t=1; extern_array[t] }
1869
1870           For structs (and most other multiword data types) the only option
1871           is to make the struct itself (or the long long, or the ...)
1872           variable:
1873
1874                   extern struct s extern_struct;
1875                   extern_struct.field -->
1876                      { volatile struct s *t=&extern_struct; t->field }
1877
1878           or
1879
1880                   extern long long extern_ll;
1881                   extern_ll -->
1882                     { volatile long long * local_ll=&extern_ll; *local_ll }
1883
1884           A third method of dealing with this difficulty is to abandon
1885           'auto-import' for the offending symbol and mark it with
1886           "__declspec(dllimport)".  However, in practice that requires using
1887           compile-time #defines to indicate whether you are building a DLL,
1888           building client code that will link to the DLL, or merely
1889           building/linking to a static library.   In making the choice
1890           between the various methods of resolving the 'direct address with
1891           constant offset' problem, you should consider typical real-world
1892           usage:
1893
1894           Original:
1895
1896                   --foo.h
1897                   extern int arr[];
1898                   --foo.c
1899                   #include "foo.h"
1900                   void main(int argc, char **argv){
1901                     printf("%d\n",arr[1]);
1902                   }
1903
1904           Solution 1:
1905
1906                   --foo.h
1907                   extern int arr[];
1908                   --foo.c
1909                   #include "foo.h"
1910                   void main(int argc, char **argv){
1911                     /* This workaround is for win32 and cygwin; do not "optimize" */
1912                     volatile int *parr = arr;
1913                     printf("%d\n",parr[1]);
1914                   }
1915
1916           Solution 2:
1917
1918                   --foo.h
1919                   /* Note: auto-export is assumed (no __declspec(dllexport)) */
1920                   #if (defined(_WIN32) || defined(__CYGWIN__)) && \
1921                     !(defined(FOO_BUILD_DLL) || defined(FOO_STATIC))
1922                   #define FOO_IMPORT __declspec(dllimport)
1923                   #else
1924                   #define FOO_IMPORT
1925                   #endif
1926                   extern FOO_IMPORT int arr[];
1927                   --foo.c
1928                   #include "foo.h"
1929                   void main(int argc, char **argv){
1930                     printf("%d\n",arr[1]);
1931                   }
1932
1933           A fourth way to avoid this problem is to re-code your library to
1934           use a functional interface rather than a data interface for the
1935           offending variables (e.g. set_foo() and get_foo() accessor
1936           functions).  [This option is specific to the i386 PE targeted port
1937           of the linker]
1938
1939       --disable-auto-import
1940           Do not attempt to do sophisticated linking of "_symbol" to
1941           "__imp__symbol" for DATA imports from DLLs.  [This option is
1942           specific to the i386 PE targeted port of the linker]
1943
1944       --enable-runtime-pseudo-reloc
1945           If your code contains expressions described in --enable-auto-import
1946           section, that is, DATA imports from DLL with non-zero offset, this
1947           switch will create a vector of 'runtime pseudo relocations' which
1948           can be used by runtime environment to adjust references to such
1949           data in your client code.  [This option is specific to the i386 PE
1950           targeted port of the linker]
1951
1952       --disable-runtime-pseudo-reloc
1953           Do not create pseudo relocations for non-zero offset DATA imports
1954           from DLLs.  [This option is specific to the i386 PE targeted port
1955           of the linker]
1956
1957       --enable-extra-pe-debug
1958           Show additional debug info related to auto-import symbol thunking.
1959           [This option is specific to the i386 PE targeted port of the
1960           linker]
1961
1962       --section-alignment
1963           Sets the section alignment.  Sections in memory will always begin
1964           at addresses which are a multiple of this number.  Defaults to
1965           0x1000.  [This option is specific to the i386 PE targeted port of
1966           the linker]
1967
1968       --stack reserve
1969       --stack reserve,commit
1970           Specify the number of bytes of memory to reserve (and optionally
1971           commit) to be used as stack for this program.  The default is 2MB
1972           reserved, 4K committed.  [This option is specific to the i386 PE
1973           targeted port of the linker]
1974
1975       --subsystem which
1976       --subsystem which:major
1977       --subsystem which:major.minor
1978           Specifies the subsystem under which your program will execute.  The
1979           legal values for which are "native", "windows", "console", "posix",
1980           and "xbox".  You may optionally set the subsystem version also.
1981           Numeric values are also accepted for which.  [This option is
1982           specific to the i386 PE targeted port of the linker]
1983
1984           The following options set flags in the "DllCharacteristics" field
1985           of the PE file header: [These options are specific to PE targeted
1986           ports of the linker]
1987
1988       --dynamicbase
1989           The image base address may be relocated using address space layout
1990           randomization (ASLR).  This feature was introduced with MS Windows
1991           Vista for i386 PE targets.
1992
1993       --forceinteg
1994           Code integrity checks are enforced.
1995
1996       --nxcompat
1997           The image is compatible with the Data Execution Prevention.  This
1998           feature was introduced with MS Windows XP SP2 for i386 PE targets.
1999
2000       --no-isolation
2001           Although the image understands isolation, do not isolate the image.
2002
2003       --no-seh
2004           The image does not use SEH. No SE handler may be called from this
2005           image.
2006
2007       --no-bind
2008           Do not bind this image.
2009
2010       --wdmdriver
2011           The driver uses the MS Windows Driver Model.
2012
2013       --tsaware
2014           The image is Terminal Server aware.
2015
2016       --insert-timestamp
2017           Insert a real timestamp into the image, rather than the default
2018           value of zero.  This will result in a slightly different results
2019           with each invocation, which could be helpful for distributing
2020           unique images.
2021
2022       The C6X uClinux target uses a binary format called DSBT to support
2023       shared libraries.  Each shared library in the system needs to have a
2024       unique index; all executables use an index of 0.
2025
2026       --dsbt-size size
2027           This option sets the number of entires in the DSBT of the current
2028           executable or shared library to size.  The default is to create a
2029           table with 64 entries.
2030
2031       --dsbt-index index
2032           This option sets the DSBT index of the current executable or shared
2033           library to index.  The default is 0, which is appropriate for
2034           generating executables.  If a shared library is generated with a
2035           DSBT index of 0, the "R_C6000_DSBT_INDEX" relocs are copied into
2036           the output file.
2037
2038           The --no-merge-exidx-entries switch disables the merging of
2039           adjacent exidx entries in frame unwind info.
2040
2041       The 68HC11 and 68HC12 linkers support specific options to control the
2042       memory bank switching mapping and trampoline code generation.
2043
2044       --no-trampoline
2045           This option disables the generation of trampoline. By default a
2046           trampoline is generated for each far function which is called using
2047           a "jsr" instruction (this happens when a pointer to a far function
2048           is taken).
2049
2050       --bank-window name
2051           This option indicates to the linker the name of the memory region
2052           in the MEMORY specification that describes the memory bank window.
2053           The definition of such region is then used by the linker to compute
2054           paging and addresses within the memory window.
2055
2056       The following options are supported to control handling of GOT
2057       generation when linking for 68K targets.
2058
2059       --got=type
2060           This option tells the linker which GOT generation scheme to use.
2061           type should be one of single, negative, multigot or target.  For
2062           more information refer to the Info entry for ld.
2063
2064       The following options are supported to control microMIPS instruction
2065       generation when linking for MIPS targets.
2066
2067       --insn32
2068       --no-insn32
2069           These options control the choice of microMIPS instructions used in
2070           code generated by the linker, such as that in the PLT or lazy
2071           binding stubs, or in relaxation.  If --insn32 is used, then the
2072           linker only uses 32-bit instruction encodings.  By default or if
2073           --no-insn32 is used, all instruction encodings are used, including
2074           16-bit ones where possible.
2075

ENVIRONMENT

2077       You can change the behaviour of ld with the environment variables
2078       "GNUTARGET", "LDEMULATION" and "COLLECT_NO_DEMANGLE".
2079
2080       "GNUTARGET" determines the input-file object format if you don't use -b
2081       (or its synonym --format).  Its value should be one of the BFD names
2082       for an input format.  If there is no "GNUTARGET" in the environment, ld
2083       uses the natural format of the target. If "GNUTARGET" is set to
2084       "default" then BFD attempts to discover the input format by examining
2085       binary input files; this method often succeeds, but there are potential
2086       ambiguities, since there is no method of ensuring that the magic number
2087       used to specify object-file formats is unique.  However, the
2088       configuration procedure for BFD on each system places the conventional
2089       format for that system first in the search-list, so ambiguities are
2090       resolved in favor of convention.
2091
2092       "LDEMULATION" determines the default emulation if you don't use the -m
2093       option.  The emulation can affect various aspects of linker behaviour,
2094       particularly the default linker script.  You can list the available
2095       emulations with the --verbose or -V options.  If the -m option is not
2096       used, and the "LDEMULATION" environment variable is not defined, the
2097       default emulation depends upon how the linker was configured.
2098
2099       Normally, the linker will default to demangling symbols.  However, if
2100       "COLLECT_NO_DEMANGLE" is set in the environment, then it will default
2101       to not demangling symbols.  This environment variable is used in a
2102       similar fashion by the "gcc" linker wrapper program.  The default may
2103       be overridden by the --demangle and --no-demangle options.
2104

SEE ALSO

2106       ar(1), nm(1), objcopy(1), objdump(1), readelf(1) and the Info entries
2107       for binutils and ld.
2108
2110       Copyright (c) 1991-2013 Free Software Foundation, Inc.
2111
2112       Permission is granted to copy, distribute and/or modify this document
2113       under the terms of the GNU Free Documentation License, Version 1.3 or
2114       any later version published by the Free Software Foundation; with no
2115       Invariant Sections, with no Front-Cover Texts, and with no Back-Cover
2116       Texts.  A copy of the license is included in the section entitled "GNU
2117       Free Documentation License".
2118
2119
2120
2121binutils-2.24                     2019-02-02                             LD(1)
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