1 LD(1) User Commands LD(1)
2
3
4
5 NAME
6 ld - link-editor for object files
7
8 SYNOPSIS
9 ld [-32 | -64] [-a | -r] [-b] [-Bdirect | nodirect]
10 [-B dynamic | static] [-B eliminate] [-B group] [-B local]
11 [-B reduce] [-B symbolic] [-c name] [-C] [-d y | n]
12 [-D token,...] [-e epsym] [-f name | -F name] [-G] [-h name]
13 [-i] [-I name] [-l x] [-L path] [-m] [-M mapfile]
14 [-N string] [-o outfile] [-p auditlib] [-P auditlib]
15 [-Q y | n] [-R path] [-s] [-S supportlib] [-t]
16 [-u symname] [-V] [-Y P,dirlist] [-z absexec]
17 [-z allextract | defaultextract | weakextract ] [-z altexec64]
18 [-z aslr[=state]] [-z assert-deflib] [ -z assert-deflib=libname]
19 [-z combreloc | nocombreloc ] [-z defs | nodefs]
20 [-z direct | nodirect] [-z endfiltee]
21 [-z fatal-warnings | nofatal-warnings ] [-z finiarray=function]
22 [-z globalaudit] [-z groupperm | nogroupperm]
23 [-z guidance[=id1,id2...] [-z help ]
24 [-z ignore | record] [-z initarray=function] [-z initfirst]
25 [-z interpose] [-z lazyload | nolazyload]
26 [-z ld32=arg1,arg2,...] [-z ld64=arg1,arg2,...]
27 [-z loadfltr] [-z muldefs] [-z nocompstrtab] [-z nodefaultlib]
28 [-z nodelete] [-z nodlopen] [-z nodump] [-z noldynsym]
29 [-z nopartial] [-z noversion] [-z now] [-z origin]
30 [-z preinitarray=function] [-z redlocsym] [-z relaxreloc]
31 [-z rescan-now] [-z recan] [-z rescan-start ... -z rescan-end]]
32 [-z target=sparc|x86] [-z text | textwarn | textoff]
33 [-z verbose] [-z wrap=symbol] filename...
34
35
36 DESCRIPTION
37 The link-editor, ld, combines relocatable object files by resolving
38 symbol references to symbol definitions, together with performing
39 relocations. ld operates in two modes, static or dynamic, as governed
40 by the -d option. In all cases, the output of ld is left in the file
41 a.out by default. See NOTES.
42
43
44 In dynamic mode, -dy, the default, relocatable object files that are
45 provided as arguments are combined to produce an executable object
46 file. This file is linked at execution with any shared object files
47 that are provided as arguments. If the -G option is specified,
48 relocatable object files are combined to produce a shared object.
49 Without the -G option, a dynamic executable is created.
50
51
52 In static mode, -dn, relocatable object files that are provided as
53 arguments are combined to produce a static executable file. If the -r
54 option is specified, relocatable object files are combined to produce
55 one relocatable object file. See Static Executables.
56
57
58 Dynamic linking is the most common model for combining relocatable
59 objects, and the eventual creation of processes within Solaris. This
60 environment tightly couples the work of the link-editor and the runtime
61 linker, ld.so.1(1). Both of these utilities, together with their
62 related technologies and utilities, are extensively documented in the
63 Linker and Libraries Guide.
64
65
66 If any argument is a library, ld by default searches the library
67 exactly once at the point the library is encountered on the argument
68 list. The library can be either a shared object or relocatable archive.
69 See ar.h(3HEAD)).
70
71
72 A shared object consists of an indivisible, whole unit that has been
73 generated by a previous link-edit of one or more input files. When the
74 link-editor processes a shared object, the entire contents of the
75 shared object become a logical part of the resulting output file image.
76 The shared object is not physically copied during the link-edit as its
77 actual inclusion is deferred until process execution. This logical
78 inclusion means that all symbol entries defined in the shared object
79 are made available to the link-editing process. See Chapter 4, Shared
80 Objects, in Linker and Libraries Guide
81
82
83 For an archive library, ld loads only those routines that define an
84 unresolved external reference. ld searches the symbol table of the
85 archive library sequentially to resolve external references that can be
86 satisfied by library members. This search is repeated until no external
87 references can be resolved by the archive. Thus, the order of members
88 in the library is functionally unimportant, unless multiple library
89 members exist that define the same external symbol. Archive libraries
90 that have interdependencies can require multiple command line
91 definitions, or the use of one of the -z rescan options. See Archive
92 Processing in Linker and Libraries Guide.
93
94
95 ld is a cross link-editor, able to link 32-bit objects or 64-bit
96 objects, for Sparc or x86 targets. ld uses the ELF class and machine
97 type of the first relocatable object on the command line to govern the
98 mode in which to operate. The mixing of 32-bit objects and 64-bit
99 objects is not permitted. Similarly, only objects of a single machine
100 type are allowed. See the -32, -64 and -z target options, and the
101 LD_NOEXEC_64 environment variable.
102
103 Static Executables
104 The creation of static executables has been discouraged for many
105 releases. In fact, 64-bit system archive libraries have never been
106 provided. Because a static executable is built against system archive
107 libraries, the executable contains system implementation details. This
108 self-containment has a number of drawbacks.
109
110 o The executable is immune to the benefits of system patches
111 delivered as shared objects. The executable therefore, must
112 be rebuilt to take advantage of many system improvements.
113
114 o The ability of the executable to run on future releases can
115 be compromised.
116
117 o The duplication of system implementation details negatively
118 affects system performance.
119
120
121 With Solaris 10, 32-bit system archive libraries are no longer
122 provided. Without these libraries, specifically libc.a, the creation
123 of static executables is no longer achievable without specialized
124 system knowledge. However, the capability of ld to process static
125 linking options, and the processing of archive libraries, remains
126 unchanged.
127
128 OPTIONS
129 The following options are supported.
130
131 -32 | -64
132
133 Creates a 32-bit, or 64-bit object.
134
135 By default, the class of the object being generated is determined
136 from the first ELF object processed from the command line. If no
137 objects are specified, the class is determined by the first object
138 encountered within the first archive processed from the command
139 line. If there are no objects or archives, the link-editor creates
140 a 32-bit object.
141
142 The -64 option is required to create a 64-bit object solely from a
143 mapfile.
144
145 This -32 or -64 options can also be used in the rare case of
146 linking entirely from an archive that contains a mixture of 32 and
147 64-bit objects. If the first object in the archive is not the class
148 of the object that is required to be created, then the -32 or -64
149 option can be used to direct the link-editor. See The 32-bit link-
150 editor and 64-bit link-editor in Linker and Libraries Guide.
151
152
153 -a
154
155 In static mode only, produces an executable object file. Undefined
156 references are not permitted. This option is the default behavior
157 for static mode. The -a option can not be used with the -r option.
158 See Static Executables under DESCRIPTION.
159
160
161 -b
162
163 In dynamic mode only, provides no special processing for dynamic
164 executable relocations that reference symbols in shared objects.
165 Without the -b option, the link-editor applies techniques within a
166 dynamic executable so that the text segment can remain read-only.
167 One technique is the creation of special position-independent
168 relocations for references to functions that are defined in shared
169 objects. Another technique arranges for data objects that are
170 defined in shared objects to be copied into the memory image of an
171 executable at runtime.
172
173 The -b option is intended for specialized dynamic objects and is
174 not recommended for general use. Its use suppresses all specialized
175 processing required to ensure an object's shareability, and can
176 even prevent the relocation of 64-bit executables.
177
178
179 -B direct | nodirect
180
181 These options govern direct binding. -B direct establishes direct
182 binding information by recording the relationship between each
183 symbol reference together with the dependency that provides the
184 definition. In addition, direct binding information is established
185 between each symbol reference and an associated definition within
186 the object being created. The runtime linker uses this information
187 to search directly for a symbol in the associated object rather
188 than to carry out a default symbol search.
189
190 Direct binding information can only be established to dependencies
191 specified with the link-edit. Thus, you should use the -z defs
192 option. Objects that wish to interpose on symbols in a direct
193 binding environment should identify themselves as interposers with
194 the -z interpose option. The use of -B direct enables -z lazyload
195 for all dependencies.
196
197 The -B nodirect option prevents any direct binding to the
198 interfaces offered by the object being created. The object being
199 created can continue to directly bind to external interfaces by
200 specifying the -z direct option. See Appendix D, Direct Bindings,
201 in Linker and Libraries Guide.
202
203
204 -B dynamic | static
205
206 Options governing library inclusion. -B dynamic is valid in dynamic
207 mode only. These options can be specified any number of times on
208 the command line as toggles: if the -B static option is given, no
209 shared objects are accepted until -B dynamic is seen. See the -l
210 option.
211
212
213 -B eliminate
214
215 Causes any global symbols, not assigned to a version definition, to
216 be eliminated from the symbol table. Version definitions can be
217 supplied by means of a mapfile to indicate the global symbols that
218 should remain visible in the generated object. This option achieves
219 the same symbol elimination as the auto-elimination directive that
220 is available as part of a mapfile version definition. This option
221 can be useful when combining versioned and non-versioned
222 relocatable objects. See also the -B local option and the -B reduce
223 option. See Defining Additional Symbols with a mapfile in Linker
224 and Libraries Guide.
225
226
227 -B group
228
229 Establishes a shared object and its dependencies as a group.
230 Objects within the group are bound to other members of the group at
231 runtime. This mode is similar to adding the object to the process
232 by using dlopen(3C) with the RTLD_GROUP mode. An object that has an
233 explicit dependency on a object identified as a group, becomes a
234 member of the group.
235
236 As the group must be self contained, use of the -B group option
237 also asserts the -z defs option.
238
239
240 -B local
241
242 Causes any global symbols, not assigned to a version definition, to
243 be reduced to local. Version definitions can be supplied by means
244 of a mapfile to indicate the global symbols that should remain
245 visible in the generated object. This option achieves the same
246 symbol reduction as the auto-reduction directive that is available
247 as part of a mapfile version definition. This option can be useful
248 when combining versioned and non-versioned relocatable objects. See
249 also the -B eliminate option and the -B reduce option. See Defining
250 Additional Symbols with a mapfile in Linker and Libraries Guide.
251
252
253 -B reduce
254
255 When generating a relocatable object, causes the reduction of
256 symbolic information defined by any version definitions. Version
257 definitions can be supplied by means of a mapfile to indicate the
258 global symbols that should remain visible in the generated object.
259 By default, when a relocatable object is generated, version
260 definitions are only recorded in the output image. The actual
261 reduction of symbolic information is carried out when the object is
262 used in the construction of a dynamic executable or shared object.
263 The -B reduce option is applied automatically when a dynamic
264 executable or shared object is created.
265
266
267 -B symbolic
268
269 In dynamic mode only. When building a shared object, binds
270 references to global symbols to their definitions, if available,
271 within the object. Normally, references to global symbols within
272 shared objects are not bound until runtime, even if definitions are
273 available. This model allows definitions of the same symbol in an
274 executable or other shared object to override the object's own
275 definition. ld issues warnings for undefined symbols unless -z defs
276 overrides.
277
278 The -B symbolic option is intended for specialized dynamic objects
279 and is not recommended for general use. To reduce the runtime
280 relocation processing that is required an object, the creation of a
281 version definition is recommended.
282
283
284 -c name
285
286 Records the configuration file name for use at runtime.
287 Configuration files can be employed to alter default search paths,
288 provide a directory cache, together with providing alternative
289 object dependencies. See crle(1).
290
291
292 -C
293
294 Demangles C++ symbol names displayed in diagnostic messages.
295
296
297 -d y | n
298
299 When -d y, the default, is specified, ld uses dynamic linking. When
300 -d n is specified, ld uses static linking. See Static Executables
301 under DESCRIPTION, and -B dynamic|static.
302
303
304 -D token,...
305
306 Prints debugging information as specified by each token, to the
307 standard error. The special token help indicates the full list of
308 tokens available. See Debugging Aids in Linker and Libraries Guide.
309
310
311 -e epsym
312 --entry epsym
313
314 Sets the entry point address for the output file to be the symbol
315 epsym.
316
317
318 -f name
319 --auxiliary name
320
321 Useful only when building a shared object. Specifies that the
322 symbol table of the shared object is used as an auxiliary filter on
323 the symbol table of the shared object specified by name. Multiple
324 instances of this option are allowed. This option can not be
325 combined with the -F option. See Generating Auxiliary Filters in
326 Linker and Libraries Guide.
327
328
329 -F name
330 --filter name
331
332 Useful only when building a shared object. Specifies that the
333 symbol table of the shared object is used as a filter on the symbol
334 table of the shared object specified by name. Multiple instances of
335 this option are allowed. This option can not be combined with the
336 -f option. See Generating Standard Filters in Linker and Libraries
337 Guide.
338
339
340 -G
341 -shared
342
343 In dynamic mode only, produces a shared object. Undefined symbols
344 are allowed. See Chapter 4, Shared Objects, in Linker and
345 Libraries Guide.
346
347
348 -h name
349 --soname name
350
351 In dynamic mode only, when building a shared object, records name
352 in the object's dynamic section. name is recorded in any dynamic
353 objects that are linked with this object rather than the object's
354 file system name. Accordingly, name is used by the runtime linker
355 as the name of the shared object to search for at runtime. See
356 Recording a Shared Object Name in Linker and Libraries Guide.
357
358
359 -i
360
361 Ignores LD_LIBRARY_PATH. This option is useful when an
362 LD_LIBRARY_PATH setting is in effect to influence the runtime
363 library search, which would interfere with the link-editing being
364 performed.
365
366
367 -I name
368 --dynamic-linker name
369
370 When building an executable, uses name as the path name of the
371 interpreter to be written into the program header. The default in
372 static mode is no interpreter. In dynamic mode, the default is the
373 name of the runtime linker, ld.so.1(1). Either case can be
374 overridden by -I name. exec(2) loads this interpreter when the
375 a.out is loaded, and passes control to the interpreter rather than
376 to the a.out directly.
377
378
379 -l x
380 --library x
381
382 Searches a library libx.so or libx.a, the conventional names for
383 shared object and archive libraries, respectively. In dynamic
384 mode, unless the -B static option is in effect, ld searches each
385 directory specified in the library search path for a libx.so or
386 libx.a file. The directory search stops at the first directory
387 containing either. ld chooses the file ending in .so if -lx expands
388 to two files with names of the form libx.so and libx.a. If no
389 libx.so is found, then ld accepts libx.a. In static mode, or when
390 the -B static option is in effect, ld selects only the file ending
391 in .a. ld searches a library when the library is encountered, so
392 the placement of -l is significant. See Linking With Additional
393 Libraries in Linker and Libraries Guide.
394
395
396 -L path
397 --library-path path
398
399 Adds path to the library search directories. ld searches for
400 libraries first in any directories specified by the -L options and
401 then in the standard directories. This option is useful only if the
402 option precedes the -l options to which the -L option applies. See
403 Directories Searched by the Link-Editor in Linker and Libraries
404 Guide.
405
406 The environment variable LD_LIBRARY_PATH can be used to supplement
407 the library search path, however the -L option is recommended, as
408 the environment variable is also interpreted by the runtime
409 environment. See LD_LIBRARY_PATH under ENVIRONMENT VARIABLES.
410
411
412 -m
413
414 Produces a memory map or listing of the input/output sections,
415 together with any non-fatal multiply-defined symbols, on the
416 standard output.
417
418
419 -M mapfile
420
421 Reads mapfile as a text file of directives to ld. This option can
422 be specified multiple times. If mapfile is a directory, then all
423 regular files, as defined by stat(2), within the directory are
424 processed. See Chapter 9, Mapfile Option, in Linker and Libraries
425 Guide. Example mapfiles are provided in /usr/lib/ld. See FILES.
426
427
428 -N string
429
430 This option causes a DT_NEEDED entry to be added to the .dynamic
431 section of the object being built. The value of the DT_NEEDED
432 string is the string that is specified on the command line. This
433 option is position dependent, and the DT_NEEDED .dynamic entry is
434 relative to the other dynamic dependencies discovered on the link-
435 edit line. This option is useful for specifying dependencies within
436 device driver relocatable objects when combined with the -dy and -r
437 options.
438
439
440 -o outfile
441 --output outfile
442
443 Produces an output object file that is named outfile. The name of
444 the default object file is a.out.
445
446
447 -p auditlib
448
449 Identifies an audit library, auditlib. This audit library is used
450 to audit the object being created at runtime. A shared object
451 identified as requiring auditing with the -p option, has this
452 requirement inherited by any object that specifies the shared
453 object as a dependency. See the -P option. See Runtime Linker
454 Auditing Interface in Linker and Libraries Guide.
455
456
457 -P auditlib
458
459 Identifies an audit library, auditlib. This audit library is used
460 to audit the dependencies of the object being created at runtime.
461 Dependency auditing can also be inherited from dependencies that
462 are identified as requiring auditing. See the -p option, and the -z
463 globalaudit option. See Runtime Linker Auditing Interface in Linker
464 and Libraries Guide.
465
466
467 -Q y | n
468
469 Under -Q y, an ident string is added to the .comment section of the
470 output file. This string identifies the version of the ld used to
471 create the file. This results in multiple ld idents when there have
472 been multiple linking steps, such as when using ld -r. This
473 identification is identical with the default action of the cc
474 command. -Q n suppresses version identification. .comment sections
475 can be manipulated by the mcs(1) utility.
476
477
478 -r
479 --relocatable
480
481 Combines relocatable object files to produce one relocatable object
482 file. ld does not complain about unresolved references. This
483 option cannot be used with the -a option.
484
485
486 -R path
487 -rpath path
488
489 A colon-separated list of directories used to specify library
490 search directories to the runtime linker. If present and not NULL,
491 the path is recorded in the output object file and passed to the
492 runtime linker. Multiple instances of this option are concatenated
493 together with each path separated by a colon. See Directories
494 Searched by the Runtime Linker in Linker and Libraries Guide.
495
496 The use of a runpath within an associated object is preferable to
497 setting global search paths such as through the LD_LIBRARY_PATH
498 environment variable. Only the runpaths that are necessary to find
499 the objects dependencies should be recorded. ldd(1) can also be
500 used to discover unused runpaths in dynamic objects, when used with
501 the -U option.
502
503 Various tokens can also be supplied with a runpath that provide a
504 flexible means of identifying system capabilities or an objects
505 location. See Appendix C, Establishing Dependencies with Dynamic
506 String Tokens, in Linker and Libraries Guide. The $ORIGIN token is
507 especially useful in allowing dynamic objects to be relocated to
508 different locations in the file system.
509
510
511 -s
512 --strip-all
513
514 Strips symbolic information from the output file. Any debugging
515 information, that is, .line, .debug*, and .stab* sections, and
516 their associated relocation entries are removed. Except for
517 relocatable files, a symbol table SHT_SYMTAB and its associated
518 string table section are not created in the output object file. The
519 elimination of a SHT_SYMTAB symbol table can reduce the .stab*
520 debugging information that is generated using the compiler drivers
521 -g option. See the -z redlocsym and -z noldynsym options.
522
523
524 -S supportlib
525
526 The shared object supportlib is loaded with ld and given
527 information regarding the linking process. Shared objects that are
528 defined by using the -S option can also be supplied using the
529 SGS_SUPPORT environment variable. See Link-Editor Support Interface
530 in Linker and Libraries Guide.
531
532
533 -t
534
535 Turns off the warning for multiply-defined symbols that have
536 different sizes or different alignments.
537
538
539 -u symname
540 --undefined symname
541
542 Enters symname as an undefined symbol in the symbol table. This
543 option is useful for loading entirely from an archive library. In
544 this instance, an unresolved reference is needed to force the
545 loading of the first routine. The placement of this option on the
546 command line is significant. This option must be placed before the
547 library that defines the symbol. See Defining Additional Symbols
548 with the u option in Linker and Libraries Guide.
549
550
551 -V
552 --version
553
554 Outputs a message giving information about the version of ld being
555 used.
556
557
558 -Y P,dirlist
559
560 Changes the default directories used for finding libraries. dirlist
561 is a colon-separated path list.
562
563
564 -z absexec
565
566 Useful only when building a dynamic executable. Specifies that
567 references to external absolute symbols should be resolved
568 immediately instead of being left for resolution at runtime. In
569 very specialized circumstances, this option removes text
570 relocations that can result in excessive swap space demands by an
571 executable.
572
573
574 -z allextract | defaultextract | weakextract
575 --whole-archive | --no-whole-archive
576
577 Alters the extraction criteria of objects from any archives that
578 follow. By default, archive members are extracted to satisfy
579 undefined references and to promote tentative definitions with data
580 definitions. Weak symbol references do not trigger extraction.
581 Under the -z allextract or --whole-archive options, all archive
582 members are extracted from the archive. Under -z weakextract, weak
583 references trigger archive extraction. The -z defaultextract or
584 --no-whole-archive options provide a means of returning to the
585 default following use of the former extract options. See Archive
586 Processing in Linker and Libraries Guide.
587
588
589 -z altexec64
590
591 Execute the 64-bit ld. The creation of very large 32-bit objects
592 can exhaust the virtual memory that is available to the 32-bit ld.
593 The -z altexec64 option can be used to force the use of the
594 associated 64-bit ld. The 64-bit ld provides a larger virtual
595 address space for building 32-bit objects. See The 32-bit link-
596 editor and 64-bit link-editor in Linker and Libraries Guide.
597
598
599 -z aslr[=state]
600
601 Specify whether the executable's address space should be randomized
602 on execution. If state is "enabled" randomization will always
603 occur when this executable is run (regardless of inherited
604 settings). If state is "disabled" randomization will never occur
605 when this executable is run. If state is omitted, ASLR is enabled.
606
607 An executable that should simply use the settings inherited from
608 its environment should not use this flag at all.
609
610
611 -z combreloc | nocombreloc
612
613 By default, ld combines multiple relocation sections when building
614 executables or shared objects. This section combination differs
615 from relocatable objects, in which relocation sections are
616 maintained in a one-to-one relationship with the sections to which
617 the relocations must be applied. The -z nocombreloc option disables
618 this merging of relocation sections, and preserves the one-to-one
619 relationship found in the original relocatable objects.
620
621 ld sorts the entries of data relocation sections by their symbol
622 reference. This sorting reduces runtime symbol lookup. When
623 multiple relocation sections are combined, this sorting produces
624 the least possible relocation overhead when objects are loaded into
625 memory, and speeds the runtime loading of dynamic objects.
626
627 Historically, the individual relocation sections were carried over
628 to any executable or shared object, and the -z combreloc option was
629 required to enable the relocation section merging previously
630 described. Relocation section merging is now the default. The -z
631 combreloc option is still accepted for the benefit of old build
632 environments, but the option is unnecessary, and has no effect.
633
634
635 -z assert-deflib
636 -z assert-deflib=libname
637
638 Enables warnings that check the location of where libraries passed
639 in with -l are found. If the link-editor finds a library on its
640 default search path it will emit a warning. This warning can be
641 made fatal in conjunction with the option -z fatal-warnings.
642 Passing libname white lists a library from this check. The library
643 must be the full name of the library, e.g. libc.so. To white list
644 multiple libraries, the -z assert-deflib=libname option can be
645 repeated multiple times. This option is useful when trying to build
646 self-contained objects where a referenced library might exist in
647 the default system library path and in alternate paths specified by
648 -L, but you only want the alternate paths to be used.
649
650
651 -z defs | nodefs
652 --no-undefined
653
654 The -z defs option and the --no-undefined option force a fatal
655 error if any undefined symbols remain at the end of the link. This
656 mode is the default when an executable is built. For historic
657 reasons, this mode is not the default when building a shared
658 object. Use of the -z defs option is recommended, as this mode
659 assures the object being built is self-contained. A self-contained
660 object has all symbolic references resolved internally, or to the
661 object's immediate dependencies.
662
663 The -z nodefs option allows undefined symbols. For historic
664 reasons, this mode is the default when a shared object is built.
665 When used with executables, the behavior of references to such
666 undefined symbols is unspecified. Use of the -z nodefs option is
667 not recommended.
668
669
670 -z direct | nodirect
671
672 Enables or disables direct binding to any dependencies that follow
673 on the command line. These options allow finer control over direct
674 binding than the global counterpart -B direct. The -z direct option
675 also differs from the -B direct option in the following areas.
676 Direct binding information is not established between a symbol
677 reference and an associated definition within the object being
678 created. Lazy loading is not enabled.
679
680
681 -z endfiltee
682
683 Marks a filtee so that when processed by a filter, the filtee
684 terminates any further filtee searches by the filter. See Reducing
685 Filtee Searches in Linker and Libraries Guide.
686
687
688 -z fatal-warnings | nofatal-warnings
689 --fatal-warnings | --no-fatal-warnings
690
691 Controls the behavior of warnings emitted from the link-editor.
692 Setting -z fatal-warnings promotes warnings emitted by the link-
693 editor to fatal errors that will cause the link-editor to fail
694 before linking. -z nofatal-warnings instead demotes these warnings
695 such that they will not cause the link-editor to exit prematurely.
696
697
698
699 -z finiarray=function
700
701 Appends an entry to the .fini_array section of the object being
702 built. If no .fini_array section is present, a section is created.
703 The new entry is initialized to point to function. See
704 Initialization and Termination Sections in Linker and Libraries
705 Guide.
706
707
708 -z globalaudit
709
710 This option supplements an audit library definition that has been
711 recorded with the -P option. This option is only meaningful when
712 building a dynamic executable. Audit libraries that are defined
713 within an object with the -P option typically allow for the
714 auditing of the immediate dependencies of the object. The -z
715 globalaudit promotes the auditor to a global auditor, thus allowing
716 the auditing of all dependencies. See Invoking the Auditing
717 Interface in Linker and Libraries Guide.
718
719 An auditor established with the -P option and the -z globalaudit
720 option, is equivalent to the auditor being established with the
721 LD_AUDIT environment variable. See ld.so.1(1).
722
723
724 -z groupperm | nogroupperm
725
726 Assigns, or deassigns each dependency that follows to a unique
727 group. The assignment of a dependency to a group has the same
728 effect as if the dependency had been built using the -B group
729 option.
730
731
732 -z guidance[=id1,id2...]
733
734 Give messages suggesting link-editor features that could improve
735 the resulting dynamic object.
736
737 Specific classes of suggestion can be silenced by specifying an
738 optional comma separated list of guidance identifiers.
739
740 The current classes of suggestion provided are:
741
742
743 Enable use of direct binding
744
745 Suggests that -z direct or -B direct be present prior to any
746 specified dependency. This allows predictable symbol binding
747 at runtime.
748
749 Can be disabled with -z guidance=nodirect
750
751
752 Enable lazy dependency loading
753
754 Suggests that -z lazyload be present prior to any specified
755 dependency. This allows the dynamic object to be loaded more
756 quickly.
757
758 Can be disabled with -z guidance=nolazyload.
759
760
761 Shared objects should define all their dependencies.
762
763 Suggests that -z defs be specified on the link-editor command
764 line. Shared objects that explicitly state all their
765 dependencies behave more predictably when used.
766
767 Can be be disabled with -z guidance=nodefs
768
769
770 Version 2 mapfile syntax
771
772 Suggests that any specified mapfiles use the more readable
773 version 2 syntax.
774
775 Can be disabled with -z guidance=nomapfile.
776
777
778 Read-only text segment
779
780 Should any runtime relocations within the text segment exist,
781 suggests that the object be compiled with position independent
782 code (PIC). Keeping large allocatable sections read-only
783 allows them to be shared between processes using a given shared
784 object.
785
786 Can be disabled with -z guidance=notext
787
788
789 No unused dependencies
790
791 Suggests that any dependency not referenced by the resulting
792 dynamic object be removed from the link-editor command line.
793
794 Can be disabled with -z guidance=nounused.
795
796
797 -z help
798 --help
799
800 Print a summary of the command line options on the standard output
801 and exit.
802
803
804 -z ignore | record
805
806 Ignores, or records, dynamic dependencies that are not referenced
807 as part of the link-edit. Ignores, or records, unreferenced ELF
808 sections from the relocatable objects that are read as part of the
809 link-edit. By default, -z record is in effect.
810
811 If an ELF section is ignored, the section is eliminated from the
812 output file being generated. A section is ignored when three
813 conditions are true. The eliminated section must contribute to an
814 allocatable segment. The eliminated section must provide no global
815 symbols. No other section from any object that contributes to the
816 link-edit, must reference an eliminated section.
817
818
819 -z initarray=function
820
821 Appends an entry to the .init_array section of the object being
822 built. If no .init_array section is present, a section is created.
823 The new entry is initialized to point to function. See
824 Initialization and Termination Sections in Linker and Libraries
825 Guide.
826
827
828 -z initfirst
829
830 Marks the object so that its runtime initialization occurs before
831 the runtime initialization of any other objects brought into the
832 process at the same time. In addition, the object runtime
833 finalization occurs after the runtime finalization of any other
834 objects removed from the process at the same time. This option is
835 only meaningful when building a shared object.
836
837
838 -z interpose
839
840 Marks the object as an interposer. At runtime, an object is
841 identified as an explicit interposer if the object has been tagged
842 using the -z interpose option. An explicit interposer is also
843 established when an object is loaded using the LD_PRELOAD
844 environment variable. Implicit interposition can occur because of
845 the load order of objects, however, this implicit interposition is
846 unknown to the runtime linker. Explicit interposition can ensure
847 that interposition takes place regardless of the order in which
848 objects are loaded. Explicit interposition also ensures that the
849 runtime linker searches for symbols in any explicit interposers
850 when direct bindings are in effect.
851
852
853 -z lazyload | nolazyload
854
855 Enables or disables the marking of dynamic dependencies to be
856 lazily loaded. Dynamic dependencies which are marked lazyload are
857 not loaded at initial process start-up. These dependencies are
858 delayed until the first binding to the object is made. Note: Lazy
859 loading requires the correct declaration of dependencies, together
860 with associated runpaths for each dynamic object used within a
861 process. See Lazy Loading of Dynamic Dependencies in Linker and
862 Libraries Guide.
863
864
865 -z ld32=arg1,arg2,...
866 -z ld64=arg1,arg2,...
867
868 The class of the link-editor is affected by the class of the output
869 file being created and by the capabilities of the underlying
870 operating system. The -z ld[32|64] options provide a means of
871 defining any link-editor argument. The defined argument is only
872 interpreted, respectively, by the 32-bit class or 64-bit class of
873 the link-editor.
874
875 For example, support libraries are class specific, so the correct
876 class of support library can be ensured using:
877
878 ld ... -z ld32=-Saudit32.so.1 -z ld64=-Saudit64.so.1 ...
879
880
881 The class of link-editor that is invoked is determined from the ELF
882 class of the first relocatable file that is seen on the command
883 line. This determination is carried out prior to any -z ld[32|64]
884 processing.
885
886
887 -z loadfltr
888
889 Marks a filter to indicate that filtees must be processed
890 immediately at runtime. Normally, filter processing is delayed
891 until a symbol reference is bound to the filter. The runtime
892 processing of an object that contains this flag mimics that which
893 occurs if the LD_LOADFLTR environment variable is in effect. See
894 the ld.so.1(1).
895
896
897 -z muldefs
898 --allow-multiple-definition
899
900 Allows multiple symbol definitions. By default, multiple symbol
901 definitions that occur between relocatable objects result in a
902 fatal error condition. This option, suppresses the error condition,
903 allowing the first symbol definition to be taken.
904
905
906 -z nocompstrtab
907
908 Disables the compression of ELF string tables. By default, string
909 compression is applied to SHT_STRTAB sections, and to SHT_PROGBITS
910 sections that have their SHF_MERGE and SHF_STRINGS section flags
911 set.
912
913
914 -z nodefaultlib
915
916 Marks the object so that the runtime default library search path,
917 used after any LD_LIBRARY_PATH or runpaths, is ignored. This option
918 implies that all dependencies of the object can be satisfied from
919 its runpath.
920
921
922 -z nodelete
923
924 Marks the object as non-deletable at runtime. This mode is similar
925 to adding the object to the process by using dlopen(3C) with the
926 RTLD_NODELETE mode.
927
928
929 -z nodlopen
930
931 Marks the object as not available to dlopen(3C), either as the
932 object specified by the dlopen(), or as any form of dependency
933 required by the object specified by the dlopen(). This option is
934 only meaningful when building a shared object.
935
936
937 -z nodump
938
939 Marks the object as not available to dldump(3C).
940
941
942 -z noldynsym
943
944 Prevents the inclusion of a .SUNW_ldynsym section in dynamic
945 executables or sharable libraries. The .SUNW_ldynsym section
946 augments the .dynsym section by providing symbols for local
947 functions. Local function symbols allow debuggers to display local
948 function names in stack traces from stripped programs. Similarly,
949 dladdr(3C) is able to supply more accurate results.
950
951 The -z noldynsym option also prevents the inclusion of the two
952 symbol sort sections that are related to the .SUNW_ldynsym section.
953 The .SUNW_dynsymsort section provides sorted access to regular
954 function and variable symbols. The .SUNW_dyntlssort section
955 provides sorted access to thread local storage (TLS) variable
956 symbols.
957
958 The .SUNW_ldynsym, .SUNW_dynsymsort, and .SUNW_dyntlssort sections,
959 which becomes part of the allocable text segment of the resulting
960 file, cannot be removed by strip(1). Therefore, the -z noldynsym
961 option is the only way to prevent their inclusion. See the -s and
962 -z redlocsym options.
963
964
965 -z nopartial
966
967 Partially initialized symbols, that are defined within relocatable
968 object files, are expanded in the output file being generated.
969
970
971 -z noversion
972
973 Does not record any versioning sections. Any version sections or
974 associated .dynamic section entries are not generated in the output
975 image.
976
977
978 -z now
979
980 Marks the object as requiring non-lazy runtime binding. This mode
981 is similar to adding the object to the process by using dlopen(3C)
982 with the RTLD_NOW mode. This mode is also similar to having the
983 LD_BIND_NOW environment variable in effect. See ld.so.1(1).
984
985
986 -z origin
987
988 Marks the object as requiring immediate $ORIGIN processing at
989 runtime. This option is only maintained for historic
990 compatibility, as the runtime analysis of objects to provide for
991 $ORIGIN processing is now default.
992
993
994 -z preinitarray=function
995
996 Appends an entry to the .preinitarray section of the object being
997 built. If no .preinitarray section is present, a section is
998 created. The new entry is initialized to point to function. See
999 Initialization and Termination Sections in Linker and Libraries
1000 Guide.
1001
1002
1003 -z redlocsym
1004
1005 Eliminates all local symbols except for the SECT symbols from the
1006 symbol table SHT_SYMTAB. All relocations that refer to local
1007 symbols are updated to refer to the corresponding SECT symbol. This
1008 option allows specialized objects to greatly reduce their symbol
1009 table sizes. Eliminated local symbols can reduce the .stab*
1010 debugging information that is generated using the compiler drivers
1011 -g option. See the -s and -z noldynsym options.
1012
1013
1014 -z relaxreloc
1015
1016 ld normally issues a fatal error upon encountering a relocation
1017 using a symbol that references an eliminated COMDAT section. If -z
1018 relaxreloc is enabled, ld instead redirects such relocations to the
1019 equivalent symbol in the COMDAT section that was kept. -z
1020 relaxreloc is a specialized option, mainly of interest to compiler
1021 authors, and is not intended for general use.
1022
1023
1024 -z rescan-now
1025 -z rescan
1026
1027 These options rescan the archive files that are provided to the
1028 link-edit. By default, archives are processed once as the archives
1029 appear on the command line. Archives are traditionally specified at
1030 the end of the command line so that their symbol definitions
1031 resolve any preceding references. However, specifying archives
1032 multiple times to satisfy their own interdependencies can be
1033 necessary.
1034
1035 -z rescan-now is a positional option, and is processed by the link-
1036 editor immediately when encountered on the command line. All
1037 archives seen on the command line up to that point are immediately
1038 reprocessed in an attempt to locate additional archive members that
1039 resolve symbol references. This archive rescanning is repeated
1040 until a pass over the archives occurs in which no new members are
1041 extracted.
1042
1043 -z rescan is a position independent option. The link-editor defers
1044 the rescan operation until after it has processed the entire
1045 command line, and then initiates a final rescan operation over all
1046 archives seen on the command line. The -z rescan operation can
1047 interact incorrectly with objects that contain
1048 initialization (.init) or finalization (.fini) sections, preventing
1049 the code in those sections from running. For this reason, -z rescan
1050 is deprecated, and use of -z rescan-now is advised.
1051
1052
1053 -z rescan-start ... -z rescan-end
1054 --start-group ... --end-group
1055 -( ... -)
1056
1057 Defines an archive rescan group. This is a positional construct,
1058 and is processed by the link-editor immediately upon encountering
1059 the closing delimiter option. Archives found within the group
1060 delimiter options are reprocessed as a group in an attempt to
1061 locate additional archive members that resolve symbol references.
1062 This archive rescanning is repeated until a pass over the
1063 archives On the occurs in which no new members are extracted.
1064 Archive rescan groups cannot be nested.
1065
1066
1067 -z target=sparc|x86
1068
1069 Specifies the machine type for the output object. Supported targets
1070 are Sparc and x86. The 32-bit machine type for the specified target
1071 is used unless the -64 option is also present, in which case the
1072 corresponding 64-bit machine type is used. By default, the machine
1073 type of the object being generated is determined from the first ELF
1074 object processed from the command line. If no objects are
1075 specified, the machine type is determined by the first object
1076 encountered within the first archive processed from the command
1077 line. If there are no objects or archives, the link-editor assumes
1078 the native machine. This option is useful when creating an object
1079 directly with ld whose input is solely from a mapfile. See the -M
1080 option. It can also be useful in the rare case of linking entirely
1081 from an archive that contains objects of different machine types
1082 for which the first object is not of the desired machine type. See
1083 The 32-bit link-editor and 64-bit link-editor in Linker and
1084 Libraries Guide.
1085
1086
1087 -z text
1088
1089 In dynamic mode only, forces a fatal error if any relocations
1090 against non-writable, allocatable sections remain. For historic
1091 reasons, this mode is not the default when building an executable
1092 or shared object. However, its use is recommended to ensure that
1093 the text segment of the dynamic object being built is shareable
1094 between multiple running processes. A shared text segment incurs
1095 the least relocation overhead when loaded into memory. See
1096 Position-Independent Code in Linker and Libraries Guide.
1097
1098
1099 -z textoff
1100
1101 In dynamic mode only, allows relocations against all allocatable
1102 sections, including non-writable ones. This mode is the default
1103 when building a shared object.
1104
1105
1106 -z textwarn
1107
1108 In dynamic mode only, lists a warning if any relocations against
1109 non-writable, allocatable sections remain. This mode is the default
1110 when building an executable.
1111
1112
1113 -z verbose
1114
1115 This option provides additional warning diagnostics during a link-
1116 edit. Presently, this option conveys suspicious use of
1117 displacement relocations. This option also conveys the restricted
1118 use of static TLS relocations when building shared objects. In
1119 future, this option might be enhanced to provide additional
1120 diagnostics that are deemed too noisy to be generated by default.
1121
1122
1123 -zwrap=symbol
1124 -wrap= symbol
1125 --wrap= symbol
1126
1127 Rename undefined references to symbol in order to allow wrapper
1128 code to be linked into the output object without having to modify
1129 source code. When -z wrap is specified, all undefined references to
1130 symbol are modified to reference __wrap_symbol, and all references
1131 to __real_symbol are modified to reference symbol. The user is
1132 expected to provide an object containing the __wrap_symbol
1133 function. This wrapper function can call __real_symbol in order to
1134 reference the actual function being wrapped.
1135
1136 The following is an example of a wrapper for the malloc(3C)
1137 function:
1138
1139 void *
1140 __wrap_malloc(size_t c)
1141 {
1142 (void) printf("malloc called with %zu\n", c);
1143 return (__real_malloc(c));
1144 }
1145
1146 If you link other code with this file using -z wrap=malloc to
1147 compile all the objects, then all calls to malloc will call the
1148 function __wrap_malloc instead. The call to __real_malloc will call
1149 the real malloc function.
1150
1151 The real and wrapped functions should be maintained in separate
1152 source files. Otherwise, the compiler or assembler may resolve the
1153 call instead of leaving that operation for the link-editor to carry
1154 out, and prevent the wrap from occurring.
1155
1156
1157 ENVIRONMENT VARIABLES
1158 LD_ALTEXEC
1159
1160 An alternative link-editor path name. ld executes, and passes
1161 control to this alternative link-editor. This environment variable
1162 provides a generic means of overriding the default link-editor that
1163 is called from the various compiler drivers. See the -z altexec64
1164 option.
1165
1166
1167 LD_LIBRARY_PATH
1168
1169 A list of directories in which to search for the libraries
1170 specified using the -l option. Multiple directories are separated
1171 by a colon. In the most general case, this environment variable
1172 contains two directory lists separated by a semicolon:
1173
1174 dirlist1;dirlist2
1175
1176
1177 If ld is called with any number of occurrences of -L, as in:
1178
1179 ld ... -Lpath1 ... -Lpathn ...
1180
1181
1182 then the search path ordering is:
1183
1184 dirlist1 path1 ... pathn dirlist2 LIBPATH
1185
1186
1187 When the list of directories does not contain a semicolon, the list
1188 is interpreted as dirlist2.
1189
1190 The LD_LIBRARY_PATH environment variable also affects the runtime
1191 linkers search for dynamic dependencies.
1192
1193 This environment variable can be specified with a _32 or _64
1194 suffix. This makes the environment variable specific, respectively,
1195 to 32-bit or 64-bit processes and overrides any non-suffixed
1196 version of the environment variable that is in effect.
1197
1198
1199 LD_NOEXEC_64
1200
1201 Suppresses the automatic execution of the 64-bit link-editor. By
1202 default, the link-editor executes the 64-bit version when the ELF
1203 class of the first relocatable file identifies a 64-bit object. The
1204 64-bit image that a 32-bit link-editor can create, has some
1205 limitations. However, some link-edits might find the use of the
1206 32-bit link-editor faster.
1207
1208
1209 LD_OPTIONS
1210
1211 A default set of options to ld. LD_OPTIONS is interpreted by ld
1212 just as though its value had been placed on the command line,
1213 immediately following the name used to invoke ld, as in:
1214
1215 ld $LD_OPTIONS ... other-arguments ...
1216
1217
1218
1219
1220 LD_RUN_PATH
1221
1222 An alternative mechanism for specifying a runpath to the link-
1223 editor. See the -R option. If both LD_RUN_PATH and the -R option
1224 are specified, -R supersedes.
1225
1226
1227 SGS_SUPPORT
1228
1229 Provides a colon-separated list of shared objects that are loaded
1230 with the link-editor and given information regarding the linking
1231 process. This environment variable can be specified with a _32 or
1232 _64 suffix. This makes the environment variable specific,
1233 respectively, to the 32-bit or 64-bit class of ld and overrides any
1234 non-suffixed version of the environment variable that is in effect.
1235 See the -S option.
1236
1237
1238
1239 Notice that environment variable-names that begin with the characters
1240 'LD_' are reserved for possible future enhancements to ld and
1241 ld.so.1(1).
1242
1243 FILES
1244 libx.so
1245 shared object libraries.
1246
1247
1248 libx.a
1249 archive libraries.
1250
1251
1252 a.out
1253 default output file.
1254
1255
1256 LIBPATH
1257 For 32-bit libraries, the default search path is
1258 /usr/ccs/lib, followed by /lib, and finally /usr/lib.
1259 For 64-bit libraries, the default search path is
1260 /lib/64, followed by /usr/lib/64.
1261
1262
1263 /usr/lib/ld
1264 A directory containing several mapfiles that can be used
1265 during link-editing. These mapfiles provide various
1266 capabilities, such as defining memory layouts, aligning
1267 bss, and defining non-executable stacks.
1268
1269
1270 ATTRIBUTES
1271 See attributes(5) for descriptions of the following attributes:
1272
1273
1274
1275
1276 +--------------------+-----------------+
1277 | ATTRIBUTE TYPE | ATTRIBUTE VALUE |
1278 +--------------------+-----------------+
1279 |Interface Stability | Committed |
1280 +--------------------+-----------------+
1281
1282 SEE ALSO
1283 as(1), crle(1), gprof(1), ld.so.1(1), ldd(1), mcs(1), pvs(1), exec(2),
1284 stat(2), dlopen(3C), dldump(3C), elf(3ELF), ar.h(3HEAD), a.out(4),
1285 attributes(5)
1286
1287
1288 Linker and Libraries Guide
1289
1290 NOTES
1291 Default options applied by ld are maintained for historic reasons. In
1292 today's programming environment, where dynamic objects dominate,
1293 alternative defaults would often make more sense. However, historic
1294 defaults must be maintained to ensure compatibility with existing
1295 program development environments. Historic defaults are called out
1296 wherever possible in this manual. For a description of the current
1297 recommended options, see Appendix A, Link-Editor Quick Reference, in
1298 Linker and Libraries Guide.
1299
1300
1301 If the file being created by ld already exists, the file is unlinked
1302 after all input files have been processed. A new file with the
1303 specified name is then created. This allows ld to create a new version
1304 of the file, while simultaneously allowing existing processes that are
1305 accessing the old file contents to continue running. If the old file
1306 has no other links, the disk space of the removed file is freed when
1307 the last process referencing the file terminates.
1308
1309
1310 The behavior of ld when the file being created already exists was
1311 changed with SXCE build 43. In older versions, the existing file was
1312 rewritten in place, an approach with the potential to corrupt any
1313 running processes that is using the file. This change has an
1314 implication for output files that have multiple hard links in the file
1315 system. Previously, all links would remain intact, with all links
1316 accessing the new file contents. The new ld behavior breaks such links,
1317 with the result that only the specified output file name references the
1318 new file. All the other links continue to reference the old file. To
1319 ensure consistent behavior, applications that rely on multiple hard
1320 links to linker output files should explicitly remove and relink the
1321 other file names.
1322
1323
1324
1325 June 6, 2016 LD(1)