* Makefile.in: Revert 2001-06-17.
[deliverable/binutils-gdb.git] / ld / ld.1
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138 .\"
139 .IX Title "LD 1"
140 .TH LD 1 "binutils-2.11.90" "2001-05-22" "GNU"
141 .UC
142 .SH "NAME"
143 ld \- Using \s-1LD\s0, the \s-1GNU\s0 linker
144 .SH "SYNOPSIS"
145 .IX Header "SYNOPSIS"
146 ld [ options ] objfile...
147 .SH "DESCRIPTION"
148 .IX Header "DESCRIPTION"
149 \&\f(CW\*(C`ld\*(C'\fR combines a number of object and archive files, relocates
150 their data and ties up symbol references. Usually the last step in
151 compiling a program is to run \f(CW\*(C`ld\*(C'\fR.
152 .PP
153 \&\f(CW\*(C`ld\*(C'\fR accepts Linker Command Language files written in
154 a superset of \s-1AT&T\s0's Link Editor Command Language syntax,
155 to provide explicit and total control over the linking process.
156 .PP
157 This man page does not describe the command language; see the
158 \&\f(CW\*(C`ld\*(C'\fR entry in \f(CW\*(C`info\*(C'\fR, or the manual
159 ld: the \s-1GNU\s0 linker, for full details on the command language and
160 on other aspects of the \s-1GNU\s0 linker.
161 .PP
162 This version of \f(CW\*(C`ld\*(C'\fR uses the general purpose \s-1BFD\s0 libraries
163 to operate on object files. This allows \f(CW\*(C`ld\*(C'\fR to read, combine, and
164 write object files in many different formats\-\-\-for example, \s-1COFF\s0 or
165 \&\f(CW\*(C`a.out\*(C'\fR. Different formats may be linked together to produce any
166 available kind of object file.
167 .PP
168 Aside from its flexibility, the \s-1GNU\s0 linker is more helpful than other
169 linkers in providing diagnostic information. Many linkers abandon
170 execution immediately upon encountering an error; whenever possible,
171 \&\f(CW\*(C`ld\*(C'\fR continues executing, allowing you to identify other errors
172 (or, in some cases, to get an output file in spite of the error).
173 .PP
174 The \s-1GNU\s0 linker \f(CW\*(C`ld\*(C'\fR is meant to cover a broad range of situations,
175 and to be as compatible as possible with other linkers. As a result,
176 you have many choices to control its behavior.
177 .SH "OPTIONS"
178 .IX Header "OPTIONS"
179 The linker supports a plethora of command-line options, but in actual
180 practice few of them are used in any particular context.
181 For instance, a frequent use of \f(CW\*(C`ld\*(C'\fR is to link standard Unix
182 object files on a standard, supported Unix system. On such a system, to
183 link a file \f(CW\*(C`hello.o\*(C'\fR:
184 .PP
185 .Vb 1
186 \& ld -o I<output> /lib/crt0.o hello.o -lc
187 .Ve
188 This tells \f(CW\*(C`ld\*(C'\fR to produce a file called \fIoutput\fR as the
189 result of linking the file \f(CW\*(C`/lib/crt0.o\*(C'\fR with \f(CW\*(C`hello.o\*(C'\fR and
190 the library \f(CW\*(C`libc.a\*(C'\fR, which will come from the standard search
191 directories. (See the discussion of the \fB\-l\fR option below.)
192 .PP
193 Some of the command-line options to \f(CW\*(C`ld\*(C'\fR may be specified at any
194 point in the command line. However, options which refer to files, such
195 as \fB\-l\fR or \fB\-T\fR, cause the file to be read at the point at
196 which the option appears in the command line, relative to the object
197 files and other file options. Repeating non-file options with a
198 different argument will either have no further effect, or override prior
199 occurrences (those further to the left on the command line) of that
200 option. Options which may be meaningfully specified more than once are
201 noted in the descriptions below.
202 .PP
203 Non-option arguments are object files or archives which are to be linked
204 together. They may follow, precede, or be mixed in with command-line
205 options, except that an object file argument may not be placed between
206 an option and its argument.
207 .PP
208 Usually the linker is invoked with at least one object file, but you can
209 specify other forms of binary input files using \fB\-l\fR, \fB\-R\fR,
210 and the script command language. If \fIno\fR binary input files at all
211 are specified, the linker does not produce any output, and issues the
212 message \fBNo input files\fR.
213 .PP
214 If the linker can not recognize the format of an object file, it will
215 assume that it is a linker script. A script specified in this way
216 augments the main linker script used for the link (either the default
217 linker script or the one specified by using \fB\-T\fR). This feature
218 permits the linker to link against a file which appears to be an object
219 or an archive, but actually merely defines some symbol values, or uses
220 \&\f(CW\*(C`INPUT\*(C'\fR or \f(CW\*(C`GROUP\*(C'\fR to load other objects. Note that
221 specifying a script in this way should only be used to augment the main
222 linker script; if you want to use some command that logically can only
223 appear once, such as the \f(CW\*(C`SECTIONS\*(C'\fR or \f(CW\*(C`MEMORY\*(C'\fR command, you
224 must replace the default linker script using the \fB\-T\fR option.
225 .PP
226 For options whose names are a single letter,
227 option arguments must either follow the option letter without intervening
228 whitespace, or be given as separate arguments immediately following the
229 option that requires them.
230 .PP
231 For options whose names are multiple letters, either one dash or two can
232 precede the option name; for example, \fB\-trace-symbol\fR and
233 \&\fB\*(--trace-symbol\fR are equivalent. Note \- there is one exception to
234 this rule. Multiple letter options that start with a lower case 'o' can
235 only be preceeded by two dashes. This is to reduce confusion with the
236 \&\fB\-o\fR option. So for example \fB\-omagic\fR sets the output file
237 name to \fBmagic\fR whereas \fB\*(--omagic\fR sets the \s-1NMAGIC\s0 flag on the
238 output.
239 .PP
240 Arguments to multiple-letter options must either be separated from the
241 option name by an equals sign, or be given as separate arguments
242 immediately following the option that requires them. For example,
243 \&\fB\*(--trace-symbol foo\fR and \fB\*(--trace-symbol=foo\fR are equivalent.
244 Unique abbreviations of the names of multiple-letter options are
245 accepted.
246 .PP
247 Note \- if the linker is being invoked indirectly, via a compiler driver
248 (eg \fBgcc\fR) then all the linker command line options should be
249 prefixed by \fB\-Wl,\fR (or whatever is appropriate for the particular
250 compiler driver) like this:
251 .PP
252 .Vb 1
253 \& gcc -Wl,--startgroup foo.o bar.o -Wl,--endgroup
254 .Ve
255 This is important, because otherwise the compiler driver program may
256 silently drop the linker options, resulting in a bad link.
257 .PP
258 Here is a table of the generic command line switches accepted by the \s-1GNU\s0
259 linker:
260 .Ip "\f(CW\*(C`\-a\f(CIkeyword\f(CW\*(C'\fR" 4
261 .IX Item "-akeyword"
262 This option is supported for \s-1HP/UX\s0 compatibility. The \fIkeyword\fR
263 argument must be one of the strings \fBarchive\fR, \fBshared\fR, or
264 \&\fBdefault\fR. \fB\-aarchive\fR is functionally equivalent to
265 \&\fB\-Bstatic\fR, and the other two keywords are functionally equivalent
266 to \fB\-Bdynamic\fR. This option may be used any number of times.
267 .Ip "\f(CW\*(C`\-A\f(CIarchitecture\f(CW\*(C'\fR" 4
268 .IX Item "-Aarchitecture"
269 .Ip "\f(CW\*(C`\-\-architecture=\f(CIarchitecture\f(CW\*(C'\fR" 4
270 .IX Item "--architecture=architecture"
271 In the current release of \f(CW\*(C`ld\*(C'\fR, this option is useful only for the
272 Intel 960 family of architectures. In that \f(CW\*(C`ld\*(C'\fR configuration, the
273 \&\fIarchitecture\fR argument identifies the particular architecture in
274 the 960 family, enabling some safeguards and modifying the
275 archive-library search path.
276 .Sp
277 Future releases of \f(CW\*(C`ld\*(C'\fR may support similar functionality for
278 other architecture families.
279 .Ip "\f(CW\*(C`\-b \f(CIinput\-format\f(CW\*(C'\fR" 4
280 .IX Item "-b input-format"
281 .Ip "\f(CW\*(C`\-\-format=\f(CIinput\-format\f(CW\*(C'\fR" 4
282 .IX Item "--format=input-format"
283 \&\f(CW\*(C`ld\*(C'\fR may be configured to support more than one kind of object
284 file. If your \f(CW\*(C`ld\*(C'\fR is configured this way, you can use the
285 \&\fB\-b\fR option to specify the binary format for input object files
286 that follow this option on the command line. Even when \f(CW\*(C`ld\*(C'\fR is
287 configured to support alternative object formats, you don't usually need
288 to specify this, as \f(CW\*(C`ld\*(C'\fR should be configured to expect as a
289 default input format the most usual format on each machine.
290 \&\fIinput-format\fR is a text string, the name of a particular format
291 supported by the \s-1BFD\s0 libraries. (You can list the available binary
292 formats with \fBobjdump \-i\fR.)
293 .Sp
294 You may want to use this option if you are linking files with an unusual
295 binary format. You can also use \fB\-b\fR to switch formats explicitly (when
296 linking object files of different formats), by including
297 \&\fB\-b\fR \fIinput-format\fR before each group of object files in a
298 particular format.
299 .Sp
300 The default format is taken from the environment variable
301 \&\f(CW\*(C`GNUTARGET\*(C'\fR.
302 .Sp
303 You can also define the input format from a script, using the command
304 \&\f(CW\*(C`TARGET\*(C'\fR;
305 .Ip "\f(CW\*(C`\-c \f(CIMRI\-commandfile\f(CW\*(C'\fR" 4
306 .IX Item "-c MRI-commandfile"
307 .Ip "\f(CW\*(C`\-\-mri\-script=\f(CIMRI\-commandfile\f(CW\*(C'\fR" 4
308 .IX Item "--mri-script=MRI-commandfile"
309 For compatibility with linkers produced by \s-1MRI\s0, \f(CW\*(C`ld\*(C'\fR accepts script
310 files written in an alternate, restricted command language, described in
311 the \s-1MRI\s0 Compatible Script Files section of \s-1GNU\s0 ld documentation.
312 Introduce \s-1MRI\s0 script files with
313 the option \fB\-c\fR; use the \fB\-T\fR option to run linker
314 scripts written in the general-purpose \f(CW\*(C`ld\*(C'\fR scripting language.
315 If \fIMRI-cmdfile\fR does not exist, \f(CW\*(C`ld\*(C'\fR looks for it in the directories
316 specified by any \fB\-L\fR options.
317 .Ip "\f(CW\*(C`\-d\*(C'\fR" 4
318 .IX Item "-d"
319 .Ip "\f(CW\*(C`\-dc\*(C'\fR" 4
320 .IX Item "-dc"
321 .Ip "\f(CW\*(C`\-dp\*(C'\fR" 4
322 .IX Item "-dp"
323 These three options are equivalent; multiple forms are supported for
324 compatibility with other linkers. They assign space to common symbols
325 even if a relocatable output file is specified (with \fB\-r\fR). The
326 script command \f(CW\*(C`FORCE_COMMON_ALLOCATION\*(C'\fR has the same effect.
327 .Ip "\f(CW\*(C`\-e \f(CIentry\f(CW\*(C'\fR" 4
328 .IX Item "-e entry"
329 .Ip "\f(CW\*(C`\-\-entry=\f(CIentry\f(CW\*(C'\fR" 4
330 .IX Item "--entry=entry"
331 Use \fIentry\fR as the explicit symbol for beginning execution of your
332 program, rather than the default entry point. If there is no symbol
333 named \fIentry\fR, the linker will try to parse \fIentry\fR as a number,
334 and use that as the entry address (the number will be interpreted in
335 base 10; you may use a leading \fB0x\fR for base 16, or a leading
336 \&\fB0\fR for base 8).
337 .Ip "\f(CW\*(C`\-E\*(C'\fR" 4
338 .IX Item "-E"
339 .Ip "\f(CW\*(C`\-\-export\-dynamic\*(C'\fR" 4
340 .IX Item "--export-dynamic"
341 When creating a dynamically linked executable, add all symbols to the
342 dynamic symbol table. The dynamic symbol table is the set of symbols
343 which are visible from dynamic objects at run time.
344 .Sp
345 If you do not use this option, the dynamic symbol table will normally
346 contain only those symbols which are referenced by some dynamic object
347 mentioned in the link.
348 .Sp
349 If you use \f(CW\*(C`dlopen\*(C'\fR to load a dynamic object which needs to refer
350 back to the symbols defined by the program, rather than some other
351 dynamic object, then you will probably need to use this option when
352 linking the program itself.
353 .Ip "\f(CW\*(C`\-EB\*(C'\fR" 4
354 .IX Item "-EB"
355 Link big-endian objects. This affects the default output format.
356 .Ip "\f(CW\*(C`\-EL\*(C'\fR" 4
357 .IX Item "-EL"
358 Link little-endian objects. This affects the default output format.
359 .Ip "\f(CW\*(C`\-f\*(C'\fR" 4
360 .IX Item "-f"
361 .Ip "\f(CW\*(C`\-\-auxiliary \f(CIname\f(CW\*(C'\fR" 4
362 .IX Item "--auxiliary name"
363 When creating an \s-1ELF\s0 shared object, set the internal \s-1DT_AUXILIARY\s0 field
364 to the specified name. This tells the dynamic linker that the symbol
365 table of the shared object should be used as an auxiliary filter on the
366 symbol table of the shared object \fIname\fR.
367 .Sp
368 If you later link a program against this filter object, then, when you
369 run the program, the dynamic linker will see the \s-1DT_AUXILIARY\s0 field. If
370 the dynamic linker resolves any symbols from the filter object, it will
371 first check whether there is a definition in the shared object
372 \&\fIname\fR. If there is one, it will be used instead of the definition
373 in the filter object. The shared object \fIname\fR need not exist.
374 Thus the shared object \fIname\fR may be used to provide an alternative
375 implementation of certain functions, perhaps for debugging or for
376 machine specific performance.
377 .Sp
378 This option may be specified more than once. The \s-1DT_AUXILIARY\s0 entries
379 will be created in the order in which they appear on the command line.
380 .Ip "\f(CW\*(C`\-F \f(CIname\f(CW\*(C'\fR" 4
381 .IX Item "-F name"
382 .Ip "\f(CW\*(C`\-\-filter \f(CIname\f(CW\*(C'\fR" 4
383 .IX Item "--filter name"
384 When creating an \s-1ELF\s0 shared object, set the internal \s-1DT_FILTER\s0 field to
385 the specified name. This tells the dynamic linker that the symbol table
386 of the shared object which is being created should be used as a filter
387 on the symbol table of the shared object \fIname\fR.
388 .Sp
389 If you later link a program against this filter object, then, when you
390 run the program, the dynamic linker will see the \s-1DT_FILTER\s0 field. The
391 dynamic linker will resolve symbols according to the symbol table of the
392 filter object as usual, but it will actually link to the definitions
393 found in the shared object \fIname\fR. Thus the filter object can be
394 used to select a subset of the symbols provided by the object
395 \&\fIname\fR.
396 .Sp
397 Some older linkers used the \f(CW\*(C`\-F\*(C'\fR option throughout a compilation
398 toolchain for specifying object-file format for both input and output
399 object files. The \s-1GNU\s0 linker uses other mechanisms for this
400 purpose: the \f(CW\*(C`\-b\*(C'\fR, \f(CW\*(C`\-\-format\*(C'\fR, \f(CW\*(C`\-\-oformat\*(C'\fR options, the
401 \&\f(CW\*(C`TARGET\*(C'\fR command in linker scripts, and the \f(CW\*(C`GNUTARGET\*(C'\fR
402 environment variable. The \s-1GNU\s0 linker will ignore the \f(CW\*(C`\-F\*(C'\fR
403 option when not creating an \s-1ELF\s0 shared object.
404 .Ip "\f(CW\*(C`\-fini \f(CIname\f(CW\*(C'\fR" 4
405 .IX Item "-fini name"
406 When creating an \s-1ELF\s0 executable or shared object, call \s-1NAME\s0 when the
407 executable or shared object is unloaded, by setting \s-1DT_FINI\s0 to the
408 address of the function. By default, the linker uses \f(CW\*(C`_fini\*(C'\fR as
409 the function to call.
410 .Ip "\f(CW\*(C`\-g\*(C'\fR" 4
411 .IX Item "-g"
412 Ignored. Provided for compatibility with other tools.
413 .Ip "\f(CW\*(C`\-G\f(CIvalue\f(CW\*(C'\fR" 4
414 .IX Item "-Gvalue"
415 .Ip "\f(CW\*(C`\-\-gpsize=\f(CIvalue\f(CW\*(C'\fR" 4
416 .IX Item "--gpsize=value"
417 Set the maximum size of objects to be optimized using the \s-1GP\s0 register to
418 \&\fIsize\fR. This is only meaningful for object file formats such as
419 \&\s-1MIPS\s0 \s-1ECOFF\s0 which supports putting large and small objects into different
420 sections. This is ignored for other object file formats.
421 .Ip "\f(CW\*(C`\-h\f(CIname\f(CW\*(C'\fR" 4
422 .IX Item "-hname"
423 .Ip "\f(CW\*(C`\-soname=\f(CIname\f(CW\*(C'\fR" 4
424 .IX Item "-soname=name"
425 When creating an \s-1ELF\s0 shared object, set the internal \s-1DT_SONAME\s0 field to
426 the specified name. When an executable is linked with a shared object
427 which has a \s-1DT_SONAME\s0 field, then when the executable is run the dynamic
428 linker will attempt to load the shared object specified by the \s-1DT_SONAME\s0
429 field rather than the using the file name given to the linker.
430 .Ip "\f(CW\*(C`\-i\*(C'\fR" 4
431 .IX Item "-i"
432 Perform an incremental link (same as option \fB\-r\fR).
433 .Ip "\f(CW\*(C`\-init \f(CIname\f(CW\*(C'\fR" 4
434 .IX Item "-init name"
435 When creating an \s-1ELF\s0 executable or shared object, call \s-1NAME\s0 when the
436 executable or shared object is loaded, by setting \s-1DT_INIT\s0 to the address
437 of the function. By default, the linker uses \f(CW\*(C`_init\*(C'\fR as the
438 function to call.
439 .Ip "\f(CW\*(C`\-l\f(CIarchive\f(CW\*(C'\fR" 4
440 .IX Item "-larchive"
441 .Ip "\f(CW\*(C`\-\-library=\f(CIarchive\f(CW\*(C'\fR" 4
442 .IX Item "--library=archive"
443 Add archive file \fIarchive\fR to the list of files to link. This
444 option may be used any number of times. \f(CW\*(C`ld\*(C'\fR will search its
445 path-list for occurrences of \f(CW\*(C`lib\f(CIarchive\f(CW.a\*(C'\fR for every
446 \&\fIarchive\fR specified.
447 .Sp
448 On systems which support shared libraries, \f(CW\*(C`ld\*(C'\fR may also search for
449 libraries with extensions other than \f(CW\*(C`.a\*(C'\fR. Specifically, on \s-1ELF\s0
450 and SunOS systems, \f(CW\*(C`ld\*(C'\fR will search a directory for a library with
451 an extension of \f(CW\*(C`.so\*(C'\fR before searching for one with an extension of
452 \&\f(CW\*(C`.a\*(C'\fR. By convention, a \f(CW\*(C`.so\*(C'\fR extension indicates a shared
453 library.
454 .Sp
455 The linker will search an archive only once, at the location where it is
456 specified on the command line. If the archive defines a symbol which
457 was undefined in some object which appeared before the archive on the
458 command line, the linker will include the appropriate \fIfile\fR\|(s) from the
459 archive. However, an undefined symbol in an object appearing later on
460 the command line will not cause the linker to search the archive again.
461 .Sp
462 See the \f(CW\*(C`\-(\*(C'\fR option for a way to force the linker to search
463 archives multiple times.
464 .Sp
465 You may list the same archive multiple times on the command line.
466 .Sp
467 This type of archive searching is standard for Unix linkers. However,
468 if you are using \f(CW\*(C`ld\*(C'\fR on \s-1AIX\s0, note that it is different from the
469 behaviour of the \s-1AIX\s0 linker.
470 .Ip "\f(CW\*(C`\-L\f(CIsearchdir\f(CW\*(C'\fR" 4
471 .IX Item "-Lsearchdir"
472 .Ip "\f(CW\*(C`\-\-library\-path=\f(CIsearchdir\f(CW\*(C'\fR" 4
473 .IX Item "--library-path=searchdir"
474 Add path \fIsearchdir\fR to the list of paths that \f(CW\*(C`ld\*(C'\fR will search
475 for archive libraries and \f(CW\*(C`ld\*(C'\fR control scripts. You may use this
476 option any number of times. The directories are searched in the order
477 in which they are specified on the command line. Directories specified
478 on the command line are searched before the default directories. All
479 \&\f(CW\*(C`\-L\*(C'\fR options apply to all \f(CW\*(C`\-l\*(C'\fR options, regardless of the
480 order in which the options appear.
481 .Sp
482 The default set of paths searched (without being specified with
483 \&\fB\-L\fR) depends on which emulation mode \f(CW\*(C`ld\*(C'\fR is using, and in
484 some cases also on how it was configured.
485 .Sp
486 The paths can also be specified in a link script with the
487 \&\f(CW\*(C`SEARCH_DIR\*(C'\fR command. Directories specified this way are searched
488 at the point in which the linker script appears in the command line.
489 .Ip "\f(CW\*(C`\-m\f(CIemulation\f(CW\*(C'\fR" 4
490 .IX Item "-memulation"
491 Emulate the \fIemulation\fR linker. You can list the available
492 emulations with the \fB\*(--verbose\fR or \fB\-V\fR options.
493 .Sp
494 If the \fB\-m\fR option is not used, the emulation is taken from the
495 \&\f(CW\*(C`LDEMULATION\*(C'\fR environment variable, if that is defined.
496 .Sp
497 Otherwise, the default emulation depends upon how the linker was
498 configured.
499 .Ip "\f(CW\*(C`\-M\*(C'\fR" 4
500 .IX Item "-M"
501 .Ip "\f(CW\*(C`\-\-print\-map\*(C'\fR" 4
502 .IX Item "--print-map"
503 Print a link map to the standard output. A link map provides
504 information about the link, including the following:
505 .RS 4
506 .Ip "\(bu" 4
507 Where object files and symbols are mapped into memory.
508 .Ip "\(bu" 4
509 How common symbols are allocated.
510 .Ip "\(bu" 4
511 All archive members included in the link, with a mention of the symbol
512 which caused the archive member to be brought in.
513 .RE
514 .RS 4
515 .RE
516 .Ip "\f(CW\*(C`\-n\*(C'\fR" 4
517 .IX Item "-n"
518 .Ip "\f(CW\*(C`\-\-nmagic\*(C'\fR" 4
519 .IX Item "--nmagic"
520 Turn off page alignment of sections, and mark the output as
521 \&\f(CW\*(C`NMAGIC\*(C'\fR if possible.
522 .Ip "\f(CW\*(C`\-N\*(C'\fR" 4
523 .IX Item "-N"
524 .Ip "\f(CW\*(C`\-\-omagic\*(C'\fR" 4
525 .IX Item "--omagic"
526 Set the text and data sections to be readable and writable. Also, do
527 not page-align the data segment. If the output format supports Unix
528 style magic numbers, mark the output as \f(CW\*(C`OMAGIC\*(C'\fR.
529 .Ip "\f(CW\*(C`\-o \f(CIoutput\f(CW\*(C'\fR" 4
530 .IX Item "-o output"
531 .Ip "\f(CW\*(C`\-\-output=\f(CIoutput\f(CW\*(C'\fR" 4
532 .IX Item "--output=output"
533 Use \fIoutput\fR as the name for the program produced by \f(CW\*(C`ld\*(C'\fR; if this
534 option is not specified, the name \fIa.out\fR is used by default. The
535 script command \f(CW\*(C`OUTPUT\*(C'\fR can also specify the output file name.
536 .Ip "\f(CW\*(C`\-O \f(CIlevel\f(CW\*(C'\fR" 4
537 .IX Item "-O level"
538 If \fIlevel\fR is a numeric values greater than zero \f(CW\*(C`ld\*(C'\fR optimizes
539 the output. This might take significantly longer and therefore probably
540 should only be enabled for the final binary.
541 .Ip "\f(CW\*(C`\-q\*(C'\fR" 4
542 .IX Item "-q"
543 .Ip "\f(CW\*(C`\-\-emit\-relocs\*(C'\fR" 4
544 .IX Item "--emit-relocs"
545 Leave relocation sections and contents in fully linked exececutables.
546 Post link analysis and optimization tools may need this information in
547 order to perform correct modifications of executables. This results
548 in larger executables.
549 .Ip "\f(CW\*(C`\-r\*(C'\fR" 4
550 .IX Item "-r"
551 .Ip "\f(CW\*(C`\-\-relocateable\*(C'\fR" 4
552 .IX Item "--relocateable"
553 Generate relocatable output\-\-\-i.e., generate an output file that can in
554 turn serve as input to \f(CW\*(C`ld\*(C'\fR. This is often called \fIpartial
555 linking\fR. As a side effect, in environments that support standard Unix
556 magic numbers, this option also sets the output file's magic number to
557 \&\f(CW\*(C`OMAGIC\*(C'\fR.
558 If this option is not specified, an absolute file is produced. When
559 linking \*(C+ programs, this option \fIwill not\fR resolve references to
560 constructors; to do that, use \fB\-Ur\fR.
561 .Sp
562 This option does the same thing as \fB\-i\fR.
563 .Ip "\f(CW\*(C`\-R \f(CIfilename\f(CW\*(C'\fR" 4
564 .IX Item "-R filename"
565 .Ip "\f(CW\*(C`\-\-just\-symbols=\f(CIfilename\f(CW\*(C'\fR" 4
566 .IX Item "--just-symbols=filename"
567 Read symbol names and their addresses from \fIfilename\fR, but do not
568 relocate it or include it in the output. This allows your output file
569 to refer symbolically to absolute locations of memory defined in other
570 programs. You may use this option more than once.
571 .Sp
572 For compatibility with other \s-1ELF\s0 linkers, if the \f(CW\*(C`\-R\*(C'\fR option is
573 followed by a directory name, rather than a file name, it is treated as
574 the \f(CW\*(C`\-rpath\*(C'\fR option.
575 .Ip "\f(CW\*(C`\-s\*(C'\fR" 4
576 .IX Item "-s"
577 .Ip "\f(CW\*(C`\-\-strip\-all\*(C'\fR" 4
578 .IX Item "--strip-all"
579 Omit all symbol information from the output file.
580 .Ip "\f(CW\*(C`\-S\*(C'\fR" 4
581 .IX Item "-S"
582 .Ip "\f(CW\*(C`\-\-strip\-debug\*(C'\fR" 4
583 .IX Item "--strip-debug"
584 Omit debugger symbol information (but not all symbols) from the output file.
585 .Ip "\f(CW\*(C`\-t\*(C'\fR" 4
586 .IX Item "-t"
587 .Ip "\f(CW\*(C`\-\-trace\*(C'\fR" 4
588 .IX Item "--trace"
589 Print the names of the input files as \f(CW\*(C`ld\*(C'\fR processes them.
590 .Ip "\f(CW\*(C`\-T \f(CIscriptfile\f(CW\*(C'\fR" 4
591 .IX Item "-T scriptfile"
592 .Ip "\f(CW\*(C`\-\-script=\f(CIscriptfile\f(CW\*(C'\fR" 4
593 .IX Item "--script=scriptfile"
594 Use \fIscriptfile\fR as the linker script. This script replaces
595 \&\f(CW\*(C`ld\*(C'\fR's default linker script (rather than adding to it), so
596 \&\fIcommandfile\fR must specify everything necessary to describe the
597 output file. You must use this option if you want to use a command
598 which can only appear once in a linker script, such as the
599 \&\f(CW\*(C`SECTIONS\*(C'\fR or \f(CW\*(C`MEMORY\*(C'\fR command. If
600 \&\fIscriptfile\fR does not exist in the current directory, \f(CW\*(C`ld\*(C'\fR
601 looks for it in the directories specified by any preceding \fB\-L\fR
602 options. Multiple \fB\-T\fR options accumulate.
603 .Ip "\f(CW\*(C`\-u \f(CIsymbol\f(CW\*(C'\fR" 4
604 .IX Item "-u symbol"
605 .Ip "\f(CW\*(C`\-\-undefined=\f(CIsymbol\f(CW\*(C'\fR" 4
606 .IX Item "--undefined=symbol"
607 Force \fIsymbol\fR to be entered in the output file as an undefined
608 symbol. Doing this may, for example, trigger linking of additional
609 modules from standard libraries. \fB\-u\fR may be repeated with
610 different option arguments to enter additional undefined symbols. This
611 option is equivalent to the \f(CW\*(C`EXTERN\*(C'\fR linker script command.
612 .Ip "\f(CW\*(C`\-Ur\*(C'\fR" 4
613 .IX Item "-Ur"
614 For anything other than \*(C+ programs, this option is equivalent to
615 \&\fB\-r\fR: it generates relocatable output\-\-\-i.e., an output file that can in
616 turn serve as input to \f(CW\*(C`ld\*(C'\fR. When linking \*(C+ programs, \fB\-Ur\fR
617 \&\fIdoes\fR resolve references to constructors, unlike \fB\-r\fR.
618 It does not work to use \fB\-Ur\fR on files that were themselves linked
619 with \fB\-Ur\fR; once the constructor table has been built, it cannot
620 be added to. Use \fB\-Ur\fR only for the last partial link, and
621 \&\fB\-r\fR for the others.
622 .Ip "\f(CW\*(C`\-\-unique[=\f(CI\s\-1SECTION\s0\f(CW]\*(C'\fR" 4
623 .IX Item "--unique[=SECTION]"
624 Creates a separate output section for every input section matching
625 \&\fI\s-1SECTION\s0\fR, or if the optional wildcard \fI\s-1SECTION\s0\fR argument is
626 missing, for every orphan input section. An orphan section is one not
627 specifically mentioned in a linker script. You may use this option
628 multiple times on the command line; It prevents the normal merging of
629 input sections with the same name, overriding output section assignments
630 in a linker script.
631 .Ip "\f(CW\*(C`\-v\*(C'\fR" 4
632 .IX Item "-v"
633 .Ip "\f(CW\*(C`\-\-version\*(C'\fR" 4
634 .IX Item "--version"
635 .Ip "\f(CW\*(C`\-V\*(C'\fR" 4
636 .IX Item "-V"
637 Display the version number for \f(CW\*(C`ld\*(C'\fR. The \f(CW\*(C`\-V\*(C'\fR option also
638 lists the supported emulations.
639 .Ip "\f(CW\*(C`\-x\*(C'\fR" 4
640 .IX Item "-x"
641 .Ip "\f(CW\*(C`\-\-discard\-all\*(C'\fR" 4
642 .IX Item "--discard-all"
643 Delete all local symbols.
644 .Ip "\f(CW\*(C`\-X\*(C'\fR" 4
645 .IX Item "-X"
646 .Ip "\f(CW\*(C`\-\-discard\-locals\*(C'\fR" 4
647 .IX Item "--discard-locals"
648 Delete all temporary local symbols. For most targets, this is all local
649 symbols whose names begin with \fBL\fR.
650 .Ip "\f(CW\*(C`\-y \f(CIsymbol\f(CW\*(C'\fR" 4
651 .IX Item "-y symbol"
652 .Ip "\f(CW\*(C`\-\-trace\-symbol=\f(CIsymbol\f(CW\*(C'\fR" 4
653 .IX Item "--trace-symbol=symbol"
654 Print the name of each linked file in which \fIsymbol\fR appears. This
655 option may be given any number of times. On many systems it is necessary
656 to prepend an underscore.
657 .Sp
658 This option is useful when you have an undefined symbol in your link but
659 don't know where the reference is coming from.
660 .Ip "\f(CW\*(C`\-Y \f(CIpath\f(CW\*(C'\fR" 4
661 .IX Item "-Y path"
662 Add \fIpath\fR to the default library search path. This option exists
663 for Solaris compatibility.
664 .Ip "\f(CW\*(C`\-z \f(CIkeyword\f(CW\*(C'\fR" 4
665 .IX Item "-z keyword"
666 The recognized keywords are \f(CW\*(C`initfirst\*(C'\fR, \f(CW\*(C`interpose\*(C'\fR,
667 \&\f(CW\*(C`loadfltr\*(C'\fR, \f(CW\*(C`nodefaultlib\*(C'\fR, \f(CW\*(C`nodelete\*(C'\fR, \f(CW\*(C`nodlopen\*(C'\fR,
668 \&\f(CW\*(C`nodump\*(C'\fR, \f(CW\*(C`now\*(C'\fR and \f(CW\*(C`origin\*(C'\fR. The other keywords are
669 ignored for Solaris compatibility. \f(CW\*(C`initfirst\*(C'\fR marks the object
670 to be initialized first at runtime before any other objects.
671 \&\f(CW\*(C`interpose\*(C'\fR marks the object that its symbol table interposes
672 before all symbols but the primary executable. \f(CW\*(C`loadfltr\*(C'\fR marks
673 the object that its filtees be processed immediately at runtime.
674 \&\f(CW\*(C`nodefaultlib\*(C'\fR marks the object that the search for dependencies
675 of this object will ignore any default library search paths.
676 \&\f(CW\*(C`nodelete\*(C'\fR marks the object shouldn't be unloaded at runtime.
677 \&\f(CW\*(C`nodlopen\*(C'\fR marks the object not available to \f(CW\*(C`dlopen\*(C'\fR.
678 \&\f(CW\*(C`nodump\*(C'\fR marks the object can not be dumped by \f(CW\*(C`dldump\*(C'\fR.
679 \&\f(CW\*(C`now\*(C'\fR marks the object with the non-lazy runtime binding.
680 \&\f(CW\*(C`origin\*(C'\fR marks the object may contain \f(CW$ORIGIN\fR.
681 \&\f(CW\*(C`defs\*(C'\fR disallows undefined symbols.
682 .Ip "\f(CW\*(C`\-( \f(CIarchives\f(CW \-)\*(C'\fR" 4
683 .IX Item "-( archives -)"
684 .Ip "\f(CW\*(C`\-\-start\-group \f(CIarchives\f(CW \-\-end\-group\*(C'\fR" 4
685 .IX Item "--start-group archives --end-group"
686 The \fIarchives\fR should be a list of archive files. They may be
687 either explicit file names, or \fB\-l\fR options.
688 .Sp
689 The specified archives are searched repeatedly until no new undefined
690 references are created. Normally, an archive is searched only once in
691 the order that it is specified on the command line. If a symbol in that
692 archive is needed to resolve an undefined symbol referred to by an
693 object in an archive that appears later on the command line, the linker
694 would not be able to resolve that reference. By grouping the archives,
695 they all be searched repeatedly until all possible references are
696 resolved.
697 .Sp
698 Using this option has a significant performance cost. It is best to use
699 it only when there are unavoidable circular references between two or
700 more archives.
701 .Ip "\f(CW\*(C`\-assert \f(CIkeyword\f(CW\*(C'\fR" 4
702 .IX Item "-assert keyword"
703 This option is ignored for SunOS compatibility.
704 .Ip "\f(CW\*(C`\-Bdynamic\*(C'\fR" 4
705 .IX Item "-Bdynamic"
706 .Ip "\f(CW\*(C`\-dy\*(C'\fR" 4
707 .IX Item "-dy"
708 .Ip "\f(CW\*(C`\-call_shared\*(C'\fR" 4
709 .IX Item "-call_shared"
710 Link against dynamic libraries. This is only meaningful on platforms
711 for which shared libraries are supported. This option is normally the
712 default on such platforms. The different variants of this option are
713 for compatibility with various systems. You may use this option
714 multiple times on the command line: it affects library searching for
715 \&\f(CW\*(C`\-l\*(C'\fR options which follow it.
716 .Ip "\f(CW\*(C`\-Bgroup\*(C'\fR" 4
717 .IX Item "-Bgroup"
718 Set the \f(CW\*(C`DF_1_GROUP\*(C'\fR flag in the \f(CW\*(C`DT_FLAGS_1\*(C'\fR entry in the dynamic
719 section. This causes the runtime linker to handle lookups in this
720 object and its dependencies to be performed only inside the group.
721 \&\f(CW\*(C`\-\-no\-undefined\*(C'\fR is implied. This option is only meaningful on \s-1ELF\s0
722 platforms which support shared libraries.
723 .Ip "\f(CW\*(C`\-Bstatic\*(C'\fR" 4
724 .IX Item "-Bstatic"
725 .Ip "\f(CW\*(C`\-dn\*(C'\fR" 4
726 .IX Item "-dn"
727 .Ip "\f(CW\*(C`\-non_shared\*(C'\fR" 4
728 .IX Item "-non_shared"
729 .Ip "\f(CW\*(C`\-static\*(C'\fR" 4
730 .IX Item "-static"
731 Do not link against shared libraries. This is only meaningful on
732 platforms for which shared libraries are supported. The different
733 variants of this option are for compatibility with various systems. You
734 may use this option multiple times on the command line: it affects
735 library searching for \f(CW\*(C`\-l\*(C'\fR options which follow it.
736 .Ip "\f(CW\*(C`\-Bsymbolic\*(C'\fR" 4
737 .IX Item "-Bsymbolic"
738 When creating a shared library, bind references to global symbols to the
739 definition within the shared library, if any. Normally, it is possible
740 for a program linked against a shared library to override the definition
741 within the shared library. This option is only meaningful on \s-1ELF\s0
742 platforms which support shared libraries.
743 .Ip "\f(CW\*(C`\-\-check\-sections\*(C'\fR" 4
744 .IX Item "--check-sections"
745 .Ip "\f(CW\*(C`\-\-no\-check\-sections\*(C'\fR" 4
746 .IX Item "--no-check-sections"
747 Asks the linker \fInot\fR to check section addresses after they have
748 been assigned to see if there any overlaps. Normally the linker will
749 perform this check, and if it finds any overlaps it will produce
750 suitable error messages. The linker does know about, and does make
751 allowances for sections in overlays. The default behaviour can be
752 restored by using the command line switch \fB\*(--check-sections\fR.
753 .Ip "\f(CW\*(C`\-\-cref\*(C'\fR" 4
754 .IX Item "--cref"
755 Output a cross reference table. If a linker map file is being
756 generated, the cross reference table is printed to the map file.
757 Otherwise, it is printed on the standard output.
758 .Sp
759 The format of the table is intentionally simple, so that it may be
760 easily processed by a script if necessary. The symbols are printed out,
761 sorted by name. For each symbol, a list of file names is given. If the
762 symbol is defined, the first file listed is the location of the
763 definition. The remaining files contain references to the symbol.
764 .Ip "\f(CW\*(C`\-\-defsym \f(CIsymbol\f(CW=\f(CIexpression\f(CW\*(C'\fR" 4
765 .IX Item "--defsym symbol=expression"
766 Create a global symbol in the output file, containing the absolute
767 address given by \fIexpression\fR. You may use this option as many
768 times as necessary to define multiple symbols in the command line. A
769 limited form of arithmetic is supported for the \fIexpression\fR in this
770 context: you may give a hexadecimal constant or the name of an existing
771 symbol, or use \f(CW\*(C`+\*(C'\fR and \f(CW\*(C`\-\*(C'\fR to add or subtract hexadecimal
772 constants or symbols. If you need more elaborate expressions, consider
773 using the linker command language from a script. \fINote:\fR there should be no white
774 space between \fIsymbol\fR, the equals sign (``\fB=\fR''), and
775 \&\fIexpression\fR.
776 .Ip "\f(CW\*(C`\-\-demangle[=\f(CIstyle\f(CW]\*(C'\fR" 4
777 .IX Item "--demangle[=style]"
778 .Ip "\f(CW\*(C`\-\-no\-demangle\*(C'\fR" 4
779 .IX Item "--no-demangle"
780 These options control whether to demangle symbol names in error messages
781 and other output. When the linker is told to demangle, it tries to
782 present symbol names in a readable fashion: it strips leading
783 underscores if they are used by the object file format, and converts \*(C+
784 mangled symbol names into user readable names. Different compilers have
785 different mangling styles. The optional demangling style argument can be used
786 to choose an appropriate demangling style for your compiler. The linker will
787 demangle by default unless the environment variable \fB\s-1COLLECT_NO_DEMANGLE\s0\fR
788 is set. These options may be used to override the default.
789 .Ip "\f(CW\*(C`\-\-dynamic\-linker \f(CIfile\f(CW\*(C'\fR" 4
790 .IX Item "--dynamic-linker file"
791 Set the name of the dynamic linker. This is only meaningful when
792 generating dynamically linked \s-1ELF\s0 executables. The default dynamic
793 linker is normally correct; don't use this unless you know what you are
794 doing.
795 .Ip "\f(CW\*(C`\-\-embedded\-relocs\*(C'\fR" 4
796 .IX Item "--embedded-relocs"
797 This option is only meaningful when linking \s-1MIPS\s0 embedded \s-1PIC\s0 code,
798 generated by the \-membedded-pic option to the \s-1GNU\s0 compiler and
799 assembler. It causes the linker to create a table which may be used at
800 runtime to relocate any data which was statically initialized to pointer
801 values. See the code in testsuite/ld-empic for details.
802 .Ip "\f(CW\*(C`\-\-fatal\-warnings\*(C'\fR" 4
803 .IX Item "--fatal-warnings"
804 Treat all warnings as errors.
805 .Ip "\f(CW\*(C`\-\-force\-exe\-suffix\*(C'\fR" 4
806 .IX Item "--force-exe-suffix"
807 Make sure that an output file has a .exe suffix.
808 .Sp
809 If a successfully built fully linked output file does not have a
810 \&\f(CW\*(C`.exe\*(C'\fR or \f(CW\*(C`.dll\*(C'\fR suffix, this option forces the linker to copy
811 the output file to one of the same name with a \f(CW\*(C`.exe\*(C'\fR suffix. This
812 option is useful when using unmodified Unix makefiles on a Microsoft
813 Windows host, since some versions of Windows won't run an image unless
814 it ends in a \f(CW\*(C`.exe\*(C'\fR suffix.
815 .Ip "\f(CW\*(C`\-\-no\-gc\-sections\*(C'\fR" 4
816 .IX Item "--no-gc-sections"
817 .Ip "\f(CW\*(C`\-\-gc\-sections\*(C'\fR" 4
818 .IX Item "--gc-sections"
819 Enable garbage collection of unused input sections. It is ignored on
820 targets that do not support this option. This option is not compatible
821 with \fB\-r\fR, nor should it be used with dynamic linking. The default
822 behaviour (of not performing this garbage collection) can be restored by
823 specifying \fB\*(--no-gc-sections\fR on the command line.
824 .Ip "\f(CW\*(C`\-\-help\*(C'\fR" 4
825 .IX Item "--help"
826 Print a summary of the command-line options on the standard output and exit.
827 .Ip "\f(CW\*(C`\-\-target\-help\*(C'\fR" 4
828 .IX Item "--target-help"
829 Print a summary of all target specific options on the standard output and exit.
830 .Ip "\f(CW\*(C`\-Map \f(CImapfile\f(CW\*(C'\fR" 4
831 .IX Item "-Map mapfile"
832 Print a link map to the file \fImapfile\fR. See the description of the
833 \&\fB\-M\fR option, above.
834 .Ip "\f(CW\*(C`\-\-no\-keep\-memory\*(C'\fR" 4
835 .IX Item "--no-keep-memory"
836 \&\f(CW\*(C`ld\*(C'\fR normally optimizes for speed over memory usage by caching the
837 symbol tables of input files in memory. This option tells \f(CW\*(C`ld\*(C'\fR to
838 instead optimize for memory usage, by rereading the symbol tables as
839 necessary. This may be required if \f(CW\*(C`ld\*(C'\fR runs out of memory space
840 while linking a large executable.
841 .Ip "\f(CW\*(C`\-\-no\-undefined\*(C'\fR" 4
842 .IX Item "--no-undefined"
843 .Ip "\f(CW\*(C`\-z defs\*(C'\fR" 4
844 .IX Item "-z defs"
845 Normally when creating a non-symbolic shared library, undefined symbols
846 are allowed and left to be resolved by the runtime loader. These options
847 disallows such undefined symbols.
848 .Ip "\f(CW\*(C`\-\-allow\-shlib\-undefined\*(C'\fR" 4
849 .IX Item "--allow-shlib-undefined"
850 Allow undefined symbols in shared objects even when \-\-no-undefined is
851 set. The net result will be that undefined symbols in regular objects
852 will still trigger an error, but undefined symbols in shared objects
853 will be ignored. The implementation of no_undefined makes the
854 assumption that the runtime linker will choke on undefined symbols.
855 However there is at least one system (BeOS) where undefined symbols in
856 shared libraries is normal since the kernel patches them at load time to
857 select which function is most appropriate for the current architecture.
858 I.E. dynamically select an appropriate memset function. Apparently it
859 is also normal for \s-1HPPA\s0 shared libraries to have undefined symbols.
860 .Ip "\f(CW\*(C`\-\-no\-warn\-mismatch\*(C'\fR" 4
861 .IX Item "--no-warn-mismatch"
862 Normally \f(CW\*(C`ld\*(C'\fR will give an error if you try to link together input
863 files that are mismatched for some reason, perhaps because they have
864 been compiled for different processors or for different endiannesses.
865 This option tells \f(CW\*(C`ld\*(C'\fR that it should silently permit such possible
866 errors. This option should only be used with care, in cases when you
867 have taken some special action that ensures that the linker errors are
868 inappropriate.
869 .Ip "\f(CW\*(C`\-\-no\-whole\-archive\*(C'\fR" 4
870 .IX Item "--no-whole-archive"
871 Turn off the effect of the \f(CW\*(C`\-\-whole\-archive\*(C'\fR option for subsequent
872 archive files.
873 .Ip "\f(CW\*(C`\-\-noinhibit\-exec\*(C'\fR" 4
874 .IX Item "--noinhibit-exec"
875 Retain the executable output file whenever it is still usable.
876 Normally, the linker will not produce an output file if it encounters
877 errors during the link process; it exits without writing an output file
878 when it issues any error whatsoever.
879 .Ip "\f(CW\*(C`\-\-oformat \f(CIoutput\-format\f(CW\*(C'\fR" 4
880 .IX Item "--oformat output-format"
881 \&\f(CW\*(C`ld\*(C'\fR may be configured to support more than one kind of object
882 file. If your \f(CW\*(C`ld\*(C'\fR is configured this way, you can use the
883 \&\fB\*(--oformat\fR option to specify the binary format for the output
884 object file. Even when \f(CW\*(C`ld\*(C'\fR is configured to support alternative
885 object formats, you don't usually need to specify this, as \f(CW\*(C`ld\*(C'\fR
886 should be configured to produce as a default output format the most
887 usual format on each machine. \fIoutput-format\fR is a text string, the
888 name of a particular format supported by the \s-1BFD\s0 libraries. (You can
889 list the available binary formats with \fBobjdump \-i\fR.) The script
890 command \f(CW\*(C`OUTPUT_FORMAT\*(C'\fR can also specify the output format, but
891 this option overrides it.
892 .Ip "\f(CW\*(C`\-qmagic\*(C'\fR" 4
893 .IX Item "-qmagic"
894 This option is ignored for Linux compatibility.
895 .Ip "\f(CW\*(C`\-Qy\*(C'\fR" 4
896 .IX Item "-Qy"
897 This option is ignored for \s-1SVR4\s0 compatibility.
898 .Ip "\f(CW\*(C`\-\-relax\*(C'\fR" 4
899 .IX Item "--relax"
900 An option with machine dependent effects.
901 This option is only supported on a few targets.
902 .Sp
903 On some platforms, the \fB\*(--relax\fR option performs global
904 optimizations that become possible when the linker resolves addressing
905 in the program, such as relaxing address modes and synthesizing new
906 instructions in the output object file.
907 .Sp
908 On some platforms these link time global optimizations may make symbolic
909 debugging of the resulting executable impossible.
910 This is known to be
911 the case for the Matsushita \s-1MN10200\s0 and \s-1MN10300\s0 family of processors.
912 .Sp
913 On platforms where this is not supported, \fB\*(--relax\fR is accepted,
914 but ignored.
915 .Ip "\f(CW\*(C`\-\-retain\-symbols\-file \f(CIfilename\f(CW\*(C'\fR" 4
916 .IX Item "--retain-symbols-file filename"
917 Retain \fIonly\fR the symbols listed in the file \fIfilename\fR,
918 discarding all others. \fIfilename\fR is simply a flat file, with one
919 symbol name per line. This option is especially useful in environments
920 (such as VxWorks)
921 where a large global symbol table is accumulated gradually, to conserve
922 run-time memory.
923 .Sp
924 \&\fB\*(--retain-symbols-file\fR does \fInot\fR discard undefined symbols,
925 or symbols needed for relocations.
926 .Sp
927 You may only specify \fB\*(--retain-symbols-file\fR once in the command
928 line. It overrides \fB\-s\fR and \fB\-S\fR.
929 .Ip "\f(CW\*(C`\-rpath \f(CIdir\f(CW\*(C'\fR" 4
930 .IX Item "-rpath dir"
931 Add a directory to the runtime library search path. This is used when
932 linking an \s-1ELF\s0 executable with shared objects. All \f(CW\*(C`\-rpath\*(C'\fR
933 arguments are concatenated and passed to the runtime linker, which uses
934 them to locate shared objects at runtime. The \f(CW\*(C`\-rpath\*(C'\fR option is
935 also used when locating shared objects which are needed by shared
936 objects explicitly included in the link; see the description of the
937 \&\f(CW\*(C`\-rpath\-link\*(C'\fR option. If \f(CW\*(C`\-rpath\*(C'\fR is not used when linking an
938 \&\s-1ELF\s0 executable, the contents of the environment variable
939 \&\f(CW\*(C`LD_RUN_PATH\*(C'\fR will be used if it is defined.
940 .Sp
941 The \f(CW\*(C`\-rpath\*(C'\fR option may also be used on SunOS. By default, on
942 SunOS, the linker will form a runtime search patch out of all the
943 \&\f(CW\*(C`\-L\*(C'\fR options it is given. If a \f(CW\*(C`\-rpath\*(C'\fR option is used, the
944 runtime search path will be formed exclusively using the \f(CW\*(C`\-rpath\*(C'\fR
945 options, ignoring the \f(CW\*(C`\-L\*(C'\fR options. This can be useful when using
946 gcc, which adds many \f(CW\*(C`\-L\*(C'\fR options which may be on \s-1NFS\s0 mounted
947 filesystems.
948 .Sp
949 For compatibility with other \s-1ELF\s0 linkers, if the \f(CW\*(C`\-R\*(C'\fR option is
950 followed by a directory name, rather than a file name, it is treated as
951 the \f(CW\*(C`\-rpath\*(C'\fR option.
952 .Ip "\f(CW\*(C`\-rpath\-link \f(CI\s\-1DIR\s0\f(CW\*(C'\fR" 4
953 .IX Item "-rpath-link DIR"
954 When using \s-1ELF\s0 or SunOS, one shared library may require another. This
955 happens when an \f(CW\*(C`ld \-shared\*(C'\fR link includes a shared library as one
956 of the input files.
957 .Sp
958 When the linker encounters such a dependency when doing a non-shared,
959 non-relocatable link, it will automatically try to locate the required
960 shared library and include it in the link, if it is not included
961 explicitly. In such a case, the \f(CW\*(C`\-rpath\-link\*(C'\fR option
962 specifies the first set of directories to search. The
963 \&\f(CW\*(C`\-rpath\-link\*(C'\fR option may specify a sequence of directory names
964 either by specifying a list of names separated by colons, or by
965 appearing multiple times.
966 .Sp
967 This option should be used with caution as it overrides the search path
968 that may have been hard compiled into a shared library. In such a case it
969 is possible to use unintentionally a different search path than the
970 runtime linker would do.
971 .Sp
972 The linker uses the following search paths to locate required shared
973 libraries.
974 .RS 4
975 .Ip "1." 4
976 Any directories specified by \f(CW\*(C`\-rpath\-link\*(C'\fR options.
977 .Ip "2." 4
978 Any directories specified by \f(CW\*(C`\-rpath\*(C'\fR options. The difference
979 between \f(CW\*(C`\-rpath\*(C'\fR and \f(CW\*(C`\-rpath\-link\*(C'\fR is that directories
980 specified by \f(CW\*(C`\-rpath\*(C'\fR options are included in the executable and
981 used at runtime, whereas the \f(CW\*(C`\-rpath\-link\*(C'\fR option is only effective
982 at link time. It is for the native linker only.
983 .Ip "3." 4
984 On an \s-1ELF\s0 system, if the \f(CW\*(C`\-rpath\*(C'\fR and \f(CW\*(C`rpath\-link\*(C'\fR options
985 were not used, search the contents of the environment variable
986 \&\f(CW\*(C`LD_RUN_PATH\*(C'\fR. It is for the native linker only.
987 .Ip "4." 4
988 On SunOS, if the \f(CW\*(C`\-rpath\*(C'\fR option was not used, search any
989 directories specified using \f(CW\*(C`\-L\*(C'\fR options.
990 .Ip "5." 4
991 For a native linker, the contents of the environment variable
992 \&\f(CW\*(C`LD_LIBRARY_PATH\*(C'\fR.
993 .Ip "6." 4
994 For a native \s-1ELF\s0 linker, the directories in \f(CW\*(C`DT_RUNPATH\*(C'\fR or
995 \&\f(CW\*(C`DT_RPATH\*(C'\fR of a shared library are searched for shared
996 libraries needed by it. The \f(CW\*(C`DT_RPATH\*(C'\fR entries are ignored if
997 \&\f(CW\*(C`DT_RUNPATH\*(C'\fR entries exist.
998 .Ip "7." 4
999 The default directories, normally \fI/lib\fR and \fI/usr/lib\fR.
1000 .Ip "8." 4
1001 For a native linker on an \s-1ELF\s0 system, if the file \fI/etc/ld.so.conf\fR
1002 exists, the list of directories found in that file.
1003 .RE
1004 .RS 4
1005 .Sp
1006 If the required shared library is not found, the linker will issue a
1007 warning and continue with the link.
1008 .RE
1009 .Ip "\f(CW\*(C`\-shared\*(C'\fR" 4
1010 .IX Item "-shared"
1011 .Ip "\f(CW\*(C`\-Bshareable\*(C'\fR" 4
1012 .IX Item "-Bshareable"
1013 Create a shared library. This is currently only supported on \s-1ELF\s0, \s-1XCOFF\s0
1014 and SunOS platforms. On SunOS, the linker will automatically create a
1015 shared library if the \f(CW\*(C`\-e\*(C'\fR option is not used and there are
1016 undefined symbols in the link.
1017 .Ip "\f(CW\*(C`\-\-sort\-common\*(C'\fR" 4
1018 .IX Item "--sort-common"
1019 This option tells \f(CW\*(C`ld\*(C'\fR to sort the common symbols by size when it
1020 places them in the appropriate output sections. First come all the one
1021 byte symbols, then all the two bytes, then all the four bytes, and then
1022 everything else. This is to prevent gaps between symbols due to
1023 alignment constraints.
1024 .Ip "\f(CW\*(C`\-\-split\-by\-file [\f(CIsize\f(CW]\*(C'\fR" 4
1025 .IX Item "--split-by-file [size]"
1026 Similar to \f(CW\*(C`\-\-split\-by\-reloc\*(C'\fR but creates a new output section for
1027 each input file when \fIsize\fR is reached. \fIsize\fR defaults to a
1028 size of 1 if not given.
1029 .Ip "\f(CW\*(C`\-\-split\-by\-reloc [\f(CIcount\f(CW]\*(C'\fR" 4
1030 .IX Item "--split-by-reloc [count]"
1031 Tries to creates extra sections in the output file so that no single
1032 output section in the file contains more than \fIcount\fR relocations.
1033 This is useful when generating huge relocatable files for downloading into
1034 certain real time kernels with the \s-1COFF\s0 object file format; since \s-1COFF\s0
1035 cannot represent more than 65535 relocations in a single section. Note
1036 that this will fail to work with object file formats which do not
1037 support arbitrary sections. The linker will not split up individual
1038 input sections for redistribution, so if a single input section contains
1039 more than \fIcount\fR relocations one output section will contain that
1040 many relocations. \fIcount\fR defaults to a value of 32768.
1041 .Ip "\f(CW\*(C`\-\-stats\*(C'\fR" 4
1042 .IX Item "--stats"
1043 Compute and display statistics about the operation of the linker, such
1044 as execution time and memory usage.
1045 .Ip "\f(CW\*(C`\-\-traditional\-format\*(C'\fR" 4
1046 .IX Item "--traditional-format"
1047 For some targets, the output of \f(CW\*(C`ld\*(C'\fR is different in some ways from
1048 the output of some existing linker. This switch requests \f(CW\*(C`ld\*(C'\fR to
1049 use the traditional format instead.
1050 .Sp
1051 For example, on SunOS, \f(CW\*(C`ld\*(C'\fR combines duplicate entries in the
1052 symbol string table. This can reduce the size of an output file with
1053 full debugging information by over 30 percent. Unfortunately, the SunOS
1054 \&\f(CW\*(C`dbx\*(C'\fR program can not read the resulting program (\f(CW\*(C`gdb\*(C'\fR has no
1055 trouble). The \fB\*(--traditional-format\fR switch tells \f(CW\*(C`ld\*(C'\fR to not
1056 combine duplicate entries.
1057 .Ip "\f(CW\*(C`\-\-section\-start \f(CIsectionname\f(CW=\f(CIorg\f(CW\*(C'\fR" 4
1058 .IX Item "--section-start sectionname=org"
1059 Locate a section in the output file at the absolute
1060 address given by \fIorg\fR. You may use this option as many
1061 times as necessary to locate multiple sections in the command
1062 line.
1063 \&\fIorg\fR must be a single hexadecimal integer;
1064 for compatibility with other linkers, you may omit the leading
1065 \&\fB0x\fR usually associated with hexadecimal values. \fINote:\fR there
1066 should be no white space between \fIsectionname\fR, the equals
1067 sign (``\fB=\fR''), and \fIorg\fR.
1068 .Ip "\f(CW\*(C`\-Tbss \f(CIorg\f(CW\*(C'\fR" 4
1069 .IX Item "-Tbss org"
1070 .Ip "\f(CW\*(C`\-Tdata \f(CIorg\f(CW\*(C'\fR" 4
1071 .IX Item "-Tdata org"
1072 .Ip "\f(CW\*(C`\-Ttext \f(CIorg\f(CW\*(C'\fR" 4
1073 .IX Item "-Ttext org"
1074 Use \fIorg\fR as the starting address for\-\-\-respectively\-\-\-the
1075 \&\f(CW\*(C`bss\*(C'\fR, \f(CW\*(C`data\*(C'\fR, or the \f(CW\*(C`text\*(C'\fR segment of the output file.
1076 \&\fIorg\fR must be a single hexadecimal integer;
1077 for compatibility with other linkers, you may omit the leading
1078 \&\fB0x\fR usually associated with hexadecimal values.
1079 .Ip "\f(CW\*(C`\-\-dll\-verbose\*(C'\fR" 4
1080 .IX Item "--dll-verbose"
1081 .Ip "\f(CW\*(C`\-\-verbose\*(C'\fR" 4
1082 .IX Item "--verbose"
1083 Display the version number for \f(CW\*(C`ld\*(C'\fR and list the linker emulations
1084 supported. Display which input files can and cannot be opened. Display
1085 the linker script if using a default builtin script.
1086 .Ip "\f(CW\*(C`\-\-version\-script=\f(CIversion\-scriptfile\f(CW\*(C'\fR" 4
1087 .IX Item "--version-script=version-scriptfile"
1088 Specify the name of a version script to the linker. This is typically
1089 used when creating shared libraries to specify additional information
1090 about the version heirarchy for the library being created. This option
1091 is only meaningful on \s-1ELF\s0 platforms which support shared libraries.
1092 .Ip "\f(CW\*(C`\-\-warn\-common\*(C'\fR" 4
1093 .IX Item "--warn-common"
1094 Warn when a common symbol is combined with another common symbol or with
1095 a symbol definition. Unix linkers allow this somewhat sloppy practice,
1096 but linkers on some other operating systems do not. This option allows
1097 you to find potential problems from combining global symbols.
1098 Unfortunately, some C libraries use this practice, so you may get some
1099 warnings about symbols in the libraries as well as in your programs.
1100 .Sp
1101 There are three kinds of global symbols, illustrated here by C examples:
1102 .RS 4
1103 .Ip "\fBint i = 1;\fR" 4
1104 .IX Item "int i = 1;"
1105 A definition, which goes in the initialized data section of the output
1106 file.
1107 .Ip "\fBextern int i;\fR" 4
1108 .IX Item "extern int i;"
1109 An undefined reference, which does not allocate space.
1110 There must be either a definition or a common symbol for the
1111 variable somewhere.
1112 .Ip "\fBint i;\fR" 4
1113 .IX Item "int i;"
1114 A common symbol. If there are only (one or more) common symbols for a
1115 variable, it goes in the uninitialized data area of the output file.
1116 The linker merges multiple common symbols for the same variable into a
1117 single symbol. If they are of different sizes, it picks the largest
1118 size. The linker turns a common symbol into a declaration, if there is
1119 a definition of the same variable.
1120 .RE
1121 .RS 4
1122 .Sp
1123 The \fB\*(--warn-common\fR option can produce five kinds of warnings.
1124 Each warning consists of a pair of lines: the first describes the symbol
1125 just encountered, and the second describes the previous symbol
1126 encountered with the same name. One or both of the two symbols will be
1127 a common symbol.
1128 .RS 4
1129 .RE
1130 .Ip "1." 4
1131 Turning a common symbol into a reference, because there is already a
1132 definition for the symbol.
1133 .Sp
1134 .Vb 3
1135 \& I<file>(I<section>): warning: common of `I<symbol>'
1136 \& overridden by definition
1137 \& I<file>(I<section>): warning: defined here
1138 .Ve
1139 .Ip "2." 4
1140 Turning a common symbol into a reference, because a later definition for
1141 the symbol is encountered. This is the same as the previous case,
1142 except that the symbols are encountered in a different order.
1143 .Sp
1144 .Vb 3
1145 \& I<file>(I<section>): warning: definition of `I<symbol>'
1146 \& overriding common
1147 \& I<file>(I<section>): warning: common is here
1148 .Ve
1149 .Ip "3." 4
1150 Merging a common symbol with a previous same-sized common symbol.
1151 .Sp
1152 .Vb 3
1153 \& I<file>(I<section>): warning: multiple common
1154 \& of `I<symbol>'
1155 \& I<file>(I<section>): warning: previous common is here
1156 .Ve
1157 .Ip "4." 4
1158 Merging a common symbol with a previous larger common symbol.
1159 .Sp
1160 .Vb 3
1161 \& I<file>(I<section>): warning: common of `I<symbol>'
1162 \& overridden by larger common
1163 \& I<file>(I<section>): warning: larger common is here
1164 .Ve
1165 .Ip "5." 4
1166 Merging a common symbol with a previous smaller common symbol. This is
1167 the same as the previous case, except that the symbols are
1168 encountered in a different order.
1169 .Sp
1170 .Vb 3
1171 \& I<file>(I<section>): warning: common of `I<symbol>'
1172 \& overriding smaller common
1173 \& I<file>(I<section>): warning: smaller common is here
1174 .Ve
1175 .RE
1176 .RS 4
1177 .RE
1178 .Ip "\f(CW\*(C`\-\-warn\-constructors\*(C'\fR" 4
1179 .IX Item "--warn-constructors"
1180 Warn if any global constructors are used. This is only useful for a few
1181 object file formats. For formats like \s-1COFF\s0 or \s-1ELF\s0, the linker can not
1182 detect the use of global constructors.
1183 .Ip "\f(CW\*(C`\-\-warn\-multiple\-gp\*(C'\fR" 4
1184 .IX Item "--warn-multiple-gp"
1185 Warn if multiple global pointer values are required in the output file.
1186 This is only meaningful for certain processors, such as the Alpha.
1187 Specifically, some processors put large-valued constants in a special
1188 section. A special register (the global pointer) points into the middle
1189 of this section, so that constants can be loaded efficiently via a
1190 base-register relative addressing mode. Since the offset in
1191 base-register relative mode is fixed and relatively small (e.g., 16
1192 bits), this limits the maximum size of the constant pool. Thus, in
1193 large programs, it is often necessary to use multiple global pointer
1194 values in order to be able to address all possible constants. This
1195 option causes a warning to be issued whenever this case occurs.
1196 .Ip "\f(CW\*(C`\-\-warn\-once\*(C'\fR" 4
1197 .IX Item "--warn-once"
1198 Only warn once for each undefined symbol, rather than once per module
1199 which refers to it.
1200 .Ip "\f(CW\*(C`\-\-warn\-section\-align\*(C'\fR" 4
1201 .IX Item "--warn-section-align"
1202 Warn if the address of an output section is changed because of
1203 alignment. Typically, the alignment will be set by an input section.
1204 The address will only be changed if it not explicitly specified; that
1205 is, if the \f(CW\*(C`SECTIONS\*(C'\fR command does not specify a start address for
1206 the section.
1207 .Ip "\f(CW\*(C`\-\-whole\-archive\*(C'\fR" 4
1208 .IX Item "--whole-archive"
1209 For each archive mentioned on the command line after the
1210 \&\f(CW\*(C`\-\-whole\-archive\*(C'\fR option, include every object file in the archive
1211 in the link, rather than searching the archive for the required object
1212 files. This is normally used to turn an archive file into a shared
1213 library, forcing every object to be included in the resulting shared
1214 library. This option may be used more than once.
1215 .Sp
1216 Two notes when using this option from gcc: First, gcc doesn't know
1217 about this option, so you have to use \f(CW\*(C`\-Wl,\-whole\-archive\*(C'\fR.
1218 Second, don't forget to use \f(CW\*(C`\-Wl,\-no\-whole\-archive\*(C'\fR after your
1219 list of archives, because gcc will add its own list of archives to
1220 your link and you may not want this flag to affect those as well.
1221 .Ip "\f(CW\*(C`\-\-wrap \f(CIsymbol\f(CW\*(C'\fR" 4
1222 .IX Item "--wrap symbol"
1223 Use a wrapper function for \fIsymbol\fR. Any undefined reference to
1224 \&\fIsymbol\fR will be resolved to \f(CW\*(C`_\|_wrap_\f(CIsymbol\f(CW\*(C'\fR. Any
1225 undefined reference to \f(CW\*(C`_\|_real_\f(CIsymbol\f(CW\*(C'\fR will be resolved to
1226 \&\fIsymbol\fR.
1227 .Sp
1228 This can be used to provide a wrapper for a system function. The
1229 wrapper function should be called \f(CW\*(C`_\|_wrap_\f(CIsymbol\f(CW\*(C'\fR. If it
1230 wishes to call the system function, it should call
1231 \&\f(CW\*(C`_\|_real_\f(CIsymbol\f(CW\*(C'\fR.
1232 .Sp
1233 Here is a trivial example:
1234 .Sp
1235 .Vb 6
1236 \& void *
1237 \& __wrap_malloc (int c)
1238 \& {
1239 \& printf ("malloc called with %ld\en", c);
1240 \& return __real_malloc (c);
1241 \& }
1242 .Ve
1243 If you link other code with this file using \f(CW\*(C`\-\-wrap malloc\*(C'\fR, then
1244 all calls to \f(CW\*(C`malloc\*(C'\fR will call the function \f(CW\*(C`_\|_wrap_malloc\*(C'\fR
1245 instead. The call to \f(CW\*(C`_\|_real_malloc\*(C'\fR in \f(CW\*(C`_\|_wrap_malloc\*(C'\fR will
1246 call the real \f(CW\*(C`malloc\*(C'\fR function.
1247 .Sp
1248 You may wish to provide a \f(CW\*(C`_\|_real_malloc\*(C'\fR function as well, so that
1249 links without the \f(CW\*(C`\-\-wrap\*(C'\fR option will succeed. If you do this,
1250 you should not put the definition of \f(CW\*(C`_\|_real_malloc\*(C'\fR in the same
1251 file as \f(CW\*(C`_\|_wrap_malloc\*(C'\fR; if you do, the assembler may resolve the
1252 call before the linker has a chance to wrap it to \f(CW\*(C`malloc\*(C'\fR.
1253 .Ip "\f(CW\*(C`\-\-enable\-new\-dtags\*(C'\fR" 4
1254 .IX Item "--enable-new-dtags"
1255 .Ip "\f(CW\*(C`\-\-disable\-new\-dtags\*(C'\fR" 4
1256 .IX Item "--disable-new-dtags"
1257 This linker can create the new dynamic tags in \s-1ELF\s0. But the older \s-1ELF\s0
1258 systems may not understand them. If you specify
1259 \&\f(CW\*(C`\-\-enable\-new\-dtags\*(C'\fR, the dynamic tags will be created as needed.
1260 If you specify \f(CW\*(C`\-\-disable\-new\-dtags\*(C'\fR, no new dynamic tags will be
1261 created. By default, the new dynamic tags are not created. Note that
1262 those options are only available for \s-1ELF\s0 systems.
1263 .PP
1264 The i386 \s-1PE\s0 linker supports the \f(CW\*(C`\-shared\*(C'\fR option, which causes
1265 the output to be a dynamically linked library (\s-1DLL\s0) instead of a
1266 normal executable. You should name the output \f(CW\*(C`*.dll\*(C'\fR when you
1267 use this option. In addition, the linker fully supports the standard
1268 \&\f(CW\*(C`*.def\*(C'\fR files, which may be specified on the linker command line
1269 like an object file (in fact, it should precede archives it exports
1270 symbols from, to ensure that they get linked in, just like a normal
1271 object file).
1272 .PP
1273 In addition to the options common to all targets, the i386 \s-1PE\s0 linker
1274 support additional command line options that are specific to the i386
1275 \&\s-1PE\s0 target. Options that take values may be separated from their
1276 values by either a space or an equals sign.
1277 .Ip "\f(CW\*(C`\-\-add\-stdcall\-alias\*(C'\fR" 4
1278 .IX Item "--add-stdcall-alias"
1279 If given, symbols with a stdcall suffix (@\fInn\fR) will be exported
1280 as-is and also with the suffix stripped.
1281 .Ip "\f(CW\*(C`\-\-base\-file \f(CIfile\f(CW\*(C'\fR" 4
1282 .IX Item "--base-file file"
1283 Use \fIfile\fR as the name of a file in which to save the base
1284 addresses of all the relocations needed for generating DLLs with
1285 \&\fIdlltool\fR.
1286 .Ip "\f(CW\*(C`\-\-dll\*(C'\fR" 4
1287 .IX Item "--dll"
1288 Create a \s-1DLL\s0 instead of a regular executable. You may also use
1289 \&\f(CW\*(C`\-shared\*(C'\fR or specify a \f(CW\*(C`LIBRARY\*(C'\fR in a given \f(CW\*(C`.def\*(C'\fR
1290 file.
1291 .Ip "\f(CW\*(C`\-\-enable\-stdcall\-fixup\*(C'\fR" 4
1292 .IX Item "--enable-stdcall-fixup"
1293 .Ip "\f(CW\*(C`\-\-disable\-stdcall\-fixup\*(C'\fR" 4
1294 .IX Item "--disable-stdcall-fixup"
1295 If the link finds a symbol that it cannot resolve, it will attempt to
1296 do \*(L"fuzzy linking\*(R" by looking for another defined symbol that differs
1297 only in the format of the symbol name (cdecl vs stdcall) and will
1298 resolve that symbol by linking to the match. For example, the
1299 undefined symbol \f(CW\*(C`_foo\*(C'\fR might be linked to the function
1300 \&\f(CW\*(C`_foo@12\*(C'\fR, or the undefined symbol \f(CW\*(C`_bar@16\*(C'\fR might be linked
1301 to the function \f(CW\*(C`_bar\*(C'\fR. When the linker does this, it prints a
1302 warning, since it normally should have failed to link, but sometimes
1303 import libraries generated from third-party dlls may need this feature
1304 to be usable. If you specify \f(CW\*(C`\-\-enable\-stdcall\-fixup\*(C'\fR, this
1305 feature is fully enabled and warnings are not printed. If you specify
1306 \&\f(CW\*(C`\-\-disable\-stdcall\-fixup\*(C'\fR, this feature is disabled and such
1307 mismatches are considered to be errors.
1308 .Ip "\f(CW\*(C`\-\-export\-all\-symbols\*(C'\fR" 4
1309 .IX Item "--export-all-symbols"
1310 If given, all global symbols in the objects used to build a \s-1DLL\s0 will
1311 be exported by the \s-1DLL\s0. Note that this is the default if there
1312 otherwise wouldn't be any exported symbols. When symbols are
1313 explicitly exported via \s-1DEF\s0 files or implicitly exported via function
1314 attributes, the default is to not export anything else unless this
1315 option is given. Note that the symbols \f(CW\*(C`DllMain@12\*(C'\fR,
1316 \&\f(CW\*(C`DllEntryPoint@0\*(C'\fR, and \f(CW\*(C`impure_ptr\*(C'\fR will not be automatically
1317 exported.
1318 .Ip "\f(CW\*(C`\-\-exclude\-symbols \f(CIsymbol\f(CW,\f(CIsymbol\f(CW,...\*(C'\fR" 4
1319 .IX Item "--exclude-symbols symbol,symbol,..."
1320 Specifies a list of symbols which should not be automatically
1321 exported. The symbol names may be delimited by commas or colons.
1322 .Ip "\f(CW\*(C`\-\-file\-alignment\*(C'\fR" 4
1323 .IX Item "--file-alignment"
1324 Specify the file alignment. Sections in the file will always begin at
1325 file offsets which are multiples of this number. This defaults to
1326 512.
1327 .Ip "\f(CW\*(C`\-\-heap \f(CIreserve\f(CW\*(C'\fR" 4
1328 .IX Item "--heap reserve"
1329 .Ip "\f(CW\*(C`\-\-heap \f(CIreserve\f(CW,\f(CIcommit\f(CW\*(C'\fR" 4
1330 .IX Item "--heap reserve,commit"
1331 Specify the amount of memory to reserve (and optionally commit) to be
1332 used as heap for this program. The default is 1Mb reserved, 4K
1333 committed.
1334 .Ip "\f(CW\*(C`\-\-image\-base \f(CIvalue\f(CW\*(C'\fR" 4
1335 .IX Item "--image-base value"
1336 Use \fIvalue\fR as the base address of your program or dll. This is
1337 the lowest memory location that will be used when your program or dll
1338 is loaded. To reduce the need to relocate and improve performance of
1339 your dlls, each should have a unique base address and not overlap any
1340 other dlls. The default is 0x400000 for executables, and 0x10000000
1341 for dlls.
1342 .Ip "\f(CW\*(C`\-\-kill\-at\*(C'\fR" 4
1343 .IX Item "--kill-at"
1344 If given, the stdcall suffixes (@\fInn\fR) will be stripped from
1345 symbols before they are exported.
1346 .Ip "\f(CW\*(C`\-\-major\-image\-version \f(CIvalue\f(CW\*(C'\fR" 4
1347 .IX Item "--major-image-version value"
1348 Sets the major number of the \*(L"image version\*(R". Defaults to 1.
1349 .Ip "\f(CW\*(C`\-\-major\-os\-version \f(CIvalue\f(CW\*(C'\fR" 4
1350 .IX Item "--major-os-version value"
1351 Sets the major number of the \*(L"os version\*(R". Defaults to 4.
1352 .Ip "\f(CW\*(C`\-\-major\-subsystem\-version \f(CIvalue\f(CW\*(C'\fR" 4
1353 .IX Item "--major-subsystem-version value"
1354 Sets the major number of the \*(L"subsystem version\*(R". Defaults to 4.
1355 .Ip "\f(CW\*(C`\-\-minor\-image\-version \f(CIvalue\f(CW\*(C'\fR" 4
1356 .IX Item "--minor-image-version value"
1357 Sets the minor number of the \*(L"image version\*(R". Defaults to 0.
1358 .Ip "\f(CW\*(C`\-\-minor\-os\-version \f(CIvalue\f(CW\*(C'\fR" 4
1359 .IX Item "--minor-os-version value"
1360 Sets the minor number of the \*(L"os version\*(R". Defaults to 0.
1361 .Ip "\f(CW\*(C`\-\-minor\-subsystem\-version \f(CIvalue\f(CW\*(C'\fR" 4
1362 .IX Item "--minor-subsystem-version value"
1363 Sets the minor number of the \*(L"subsystem version\*(R". Defaults to 0.
1364 .Ip "\f(CW\*(C`\-\-output\-def \f(CIfile\f(CW\*(C'\fR" 4
1365 .IX Item "--output-def file"
1366 The linker will create the file \fIfile\fR which will contain a \s-1DEF\s0
1367 file corresponding to the \s-1DLL\s0 the linker is generating. This \s-1DEF\s0 file
1368 (which should be called \f(CW\*(C`*.def\*(C'\fR) may be used to create an import
1369 library with \f(CW\*(C`dlltool\*(C'\fR or may be used as a reference to
1370 automatically or implicitly exported symbols.
1371 .Ip "\f(CW\*(C`\-\-section\-alignment\*(C'\fR" 4
1372 .IX Item "--section-alignment"
1373 Sets the section alignment. Sections in memory will always begin at
1374 addresses which are a multiple of this number. Defaults to 0x1000.
1375 .Ip "\f(CW\*(C`\-\-stack \f(CIreserve\f(CW\*(C'\fR" 4
1376 .IX Item "--stack reserve"
1377 .Ip "\f(CW\*(C`\-\-stack \f(CIreserve\f(CW,\f(CIcommit\f(CW\*(C'\fR" 4
1378 .IX Item "--stack reserve,commit"
1379 Specify the amount of memory to reserve (and optionally commit) to be
1380 used as stack for this program. The default is 32Mb reserved, 4K
1381 committed.
1382 .Ip "\f(CW\*(C`\-\-subsystem \f(CIwhich\f(CW\*(C'\fR" 4
1383 .IX Item "--subsystem which"
1384 .Ip "\f(CW\*(C`\-\-subsystem \f(CIwhich\f(CW:\f(CImajor\f(CW\*(C'\fR" 4
1385 .IX Item "--subsystem which:major"
1386 .Ip "\f(CW\*(C`\-\-subsystem \f(CIwhich\f(CW:\f(CImajor\f(CW.\f(CIminor\f(CW\*(C'\fR" 4
1387 .IX Item "--subsystem which:major.minor"
1388 Specifies the subsystem under which your program will execute. The
1389 legal values for \fIwhich\fR are \f(CW\*(C`native\*(C'\fR, \f(CW\*(C`windows\*(C'\fR,
1390 \&\f(CW\*(C`console\*(C'\fR, and \f(CW\*(C`posix\*(C'\fR. You may optionally set the
1391 subsystem version also.
1392 .SH "ENVIRONMENT"
1393 .IX Header "ENVIRONMENT"
1394 You can change the behavior of \f(CW\*(C`ld\*(C'\fR with the environment variables
1395 \&\f(CW\*(C`GNUTARGET\*(C'\fR, \f(CW\*(C`LDEMULATION\*(C'\fR, and \f(CW\*(C`COLLECT_NO_DEMANGLE\*(C'\fR.
1396 .PP
1397 \&\f(CW\*(C`GNUTARGET\*(C'\fR determines the input-file object format if you don't
1398 use \fB\-b\fR (or its synonym \fB\*(--format\fR). Its value should be one
1399 of the \s-1BFD\s0 names for an input format. If there is no
1400 \&\f(CW\*(C`GNUTARGET\*(C'\fR in the environment, \f(CW\*(C`ld\*(C'\fR uses the natural format
1401 of the target. If \f(CW\*(C`GNUTARGET\*(C'\fR is set to \f(CW\*(C`default\*(C'\fR then \s-1BFD\s0
1402 attempts to discover the input format by examining binary input files;
1403 this method often succeeds, but there are potential ambiguities, since
1404 there is no method of ensuring that the magic number used to specify
1405 object-file formats is unique. However, the configuration procedure for
1406 \&\s-1BFD\s0 on each system places the conventional format for that system first
1407 in the search-list, so ambiguities are resolved in favor of convention.
1408 .PP
1409 \&\f(CW\*(C`LDEMULATION\*(C'\fR determines the default emulation if you don't use the
1410 \&\fB\-m\fR option. The emulation can affect various aspects of linker
1411 behaviour, particularly the default linker script. You can list the
1412 available emulations with the \fB\*(--verbose\fR or \fB\-V\fR options. If
1413 the \fB\-m\fR option is not used, and the \f(CW\*(C`LDEMULATION\*(C'\fR environment
1414 variable is not defined, the default emulation depends upon how the
1415 linker was configured.
1416 .PP
1417 Normally, the linker will default to demangling symbols. However, if
1418 \&\f(CW\*(C`COLLECT_NO_DEMANGLE\*(C'\fR is set in the environment, then it will
1419 default to not demangling symbols. This environment variable is used in
1420 a similar fashion by the \f(CW\*(C`gcc\*(C'\fR linker wrapper program. The default
1421 may be overridden by the \fB\*(--demangle\fR and \fB\*(--no-demangle\fR
1422 options.
1423 .SH "SEE ALSO"
1424 .IX Header "SEE ALSO"
1425 \&\fIar\fR\|(1), \fInm\fR\|(1), \fIobjcopy\fR\|(1), \fIobjdump\fR\|(1), \fIreadelf\fR\|(1) and
1426 the Info entries for \fIbinutils\fR and
1427 \&\fIld\fR.
1428 .SH "COPYRIGHT"
1429 .IX Header "COPYRIGHT"
1430 Copyright (c) 1991, 92, 93, 94, 95, 96, 97, 98, 99, 2000 Free Software Foundation, Inc.
1431 .PP
1432 Permission is granted to copy, distribute and/or modify this document
1433 under the terms of the \s-1GNU\s0 Free Documentation License, Version 1.1
1434 or any later version published by the Free Software Foundation;
1435 with no Invariant Sections, with no Front-Cover Texts, and with no
1436 Back-Cover Texts. A copy of the license is included in the
1437 section entitled \*(L"\s-1GNU\s0 Free Documentation License\*(R".
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