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1 | .\" Copyright (c) 1991, 92, 93, 94, 95, 96, 97, 98, 1999 Free Software Foundation |
2 | .\" See section COPYING for conditions for redistribution | |
3 | .TH ld 1 "17 August 1992" "cygnus support" "GNU Development Tools" | |
4 | .de BP | |
5 | .sp | |
6 | .ti \-.2i | |
7 | \(** | |
8 | .. | |
9 | ||
10 | .SH NAME | |
11 | ld \- the GNU linker | |
12 | ||
13 | .SH SYNOPSIS | |
14 | .hy 0 | |
15 | .na | |
16 | .TP | |
17 | .B ld | |
18 | .RB "[\|" \-o " | |
19 | .I output\c | |
20 | \&\|] \c | |
21 | .I objfile\c | |
22 | \&.\|.\|. | |
23 | .br | |
24 | .RB "[\|" \-A\c | |
25 | .I architecture\c | |
26 | \&\|] | |
27 | .RB "[\|" "\-b\ "\c | |
28 | .I input-format\c | |
29 | \&\|] | |
30 | .RB "[\|" \-Bstatic "\|]" | |
31 | .RB "[\|" \-Bdynamic "\|]" | |
32 | .RB "[\|" \-Bsymbolic "\|]" | |
33 | .RB "[\|" "\-c\ "\c | |
34 | .I commandfile\c | |
35 | \&\|] | |
36 | .RB "[\|" \-\-cref "\|]" | |
37 | .RB "[\|" \-d | \-dc | \-dp\c | |
38 | \|] | |
39 | .br | |
40 | .RB "[\|" "\-defsym\ "\c | |
41 | .I symbol\c | |
42 | \& = \c | |
43 | .I expression\c | |
44 | \&\|] | |
45 | .RB "[\|" \-\-demangle "\|]" | |
46 | .RB "[\|" \-\-no\-demangle "\|]" | |
47 | .RB "[\|" "\-e\ "\c | |
48 | .I entry\c | |
49 | \&\|] | |
50 | .RB "[\|" \-embedded\-relocs "\|]" | |
51 | .RB "[\|" \-E "\|]" | |
52 | .RB "[\|" \-export\-dynamic "\|]" | |
53 | .RB "[\|" "\-f\ "\c | |
54 | .I name\c | |
55 | \&\|] | |
56 | .RB "[\|" "\-\-auxiliary\ "\c | |
57 | .I name\c | |
58 | \&\|] | |
59 | .RB "[\|" "\-F\ "\c | |
60 | .I name\c | |
61 | \&\|] | |
62 | .RB "[\|" "\-\-filter\ "\c | |
63 | .I name\c | |
64 | \&\|] | |
65 | .RB "[\|" "\-format\ "\c | |
66 | .I input-format\c | |
67 | \&\|] | |
68 | .RB "[\|" \-g "\|]" | |
69 | .RB "[\|" \-G | |
70 | .I size\c | |
71 | \&\|] | |
72 | .RB "[\|" "\-h\ "\c | |
73 | .I name\c | |
74 | \&\|] | |
75 | .RB "[\|" "\-soname\ "\c | |
76 | .I name\c | |
77 | \&\|] | |
78 | .RB "[\|" \-\-help "\|]" | |
79 | .RB "[\|" \-i "\|]" | |
80 | .RB "[\|" \-l\c | |
81 | .I ar\c | |
82 | \&\|] | |
83 | .RB "[\|" \-L\c | |
84 | .I searchdir\c | |
85 | \&\|] | |
86 | .RB "[\|" \-M "\|]" | |
87 | .RB "[\|" \-Map | |
88 | .I mapfile\c | |
89 | \&\|] | |
90 | .RB "[\|" \-m | |
91 | .I emulation\c | |
92 | \&\|] | |
93 | .RB "[\|" \-n | \-N "\|]" | |
94 | .RB "[\|" \-noinhibit-exec "\|]" | |
95 | .RB "[\|" \-no\-keep\-memory "\|]" | |
96 | .RB "[\|" \-no\-warn\-mismatch "\|]" | |
97 | .RB "[\|" \-O\c | |
98 | .I level\c | |
99 | \&\|] | |
100 | .RB "[\|" "\-oformat\ "\c | |
101 | .I output-format\c | |
102 | \&\|] | |
103 | .RB "[\|" "\-R\ "\c | |
104 | .I filename\c | |
105 | \&\|] | |
106 | .RB "[\|" \-relax "\|]" | |
107 | .RB "[\|" \-r | \-Ur "\|]" | |
108 | .RB "[\|" "\-rpath\ "\c | |
109 | .I directory\c | |
110 | \&\|] | |
111 | .RB "[\|" "\-rpath\-link\ "\c | |
112 | .I directory\c | |
113 | \&\|] | |
114 | .RB "[\|" \-S "\|]" | |
115 | .RB "[\|" \-s "\|]" | |
116 | .RB "[\|" \-shared "\|]" | |
117 | .RB "[\|" \-sort\-common "\|]" | |
118 | .RB "[\|" "\-split\-by\-reloc\ "\c | |
119 | .I count\c | |
120 | \&\|] | |
121 | .RB "[\|" \-split\-by\-file "\|]" | |
122 | .RB "[\|" "\-T\ "\c | |
123 | .I commandfile\c | |
124 | \&\|] | |
125 | .RB "[\|" "\-Ttext\ "\c | |
126 | .I textorg\c | |
127 | \&\|] | |
128 | .RB "[\|" "\-Tdata\ "\c | |
129 | .I dataorg\c | |
130 | \&\|] | |
131 | .RB "[\|" "\-Tbss\ "\c | |
132 | .I bssorg\c | |
133 | \&\|] | |
134 | .RB "[\|" \-t "\|]" | |
135 | .RB "[\|" "\-u\ "\c | |
136 | .I sym\c | |
137 | \&] | |
138 | .RB "[\|" \-V "\|]" | |
139 | .RB "[\|" \-v "\|]" | |
140 | .RB "[\|" \-\-verbose "\|]" | |
141 | .RB "[\|" \-\-version "\|]" | |
142 | .RB "[\|" \-warn\-common "\|]" | |
143 | .RB "[\|" \-warn\-constructors "\|]" | |
144 | .RB "[\|" \-warn\-multiple\-gp "\|]" | |
145 | .RB "[\|" \-warn\-once "\|]" | |
146 | .RB "[\|" \-warn\-section\-align "\|]" | |
147 | .RB "[\|" \-\-whole\-archive "\|]" | |
148 | .RB "[\|" \-\-no\-whole\-archive "\|]" | |
149 | .RB "[\|" "\-\-wrap\ "\c | |
150 | .I symbol\c | |
151 | \&\|] | |
152 | .RB "[\|" \-X "\|]" | |
153 | .RB "[\|" \-x "\|]" | |
154 | .ad b | |
155 | .hy 1 | |
156 | .SH DESCRIPTION | |
157 | \c | |
158 | .B ld\c | |
159 | \& combines a number of object and archive files, relocates | |
160 | their data and ties up symbol references. Often the last step in | |
161 | building a new compiled program to run is a call to \c | |
162 | .B ld\c | |
163 | \&. | |
164 | ||
165 | \c | |
166 | .B ld\c | |
167 | \& accepts Linker Command Language files | |
168 | to provide explicit and total control over the linking process. | |
169 | This man page does not describe the command language; see the `\|\c | |
170 | .B ld\c | |
171 | \|' entry in `\|\c | |
172 | .B info\c | |
173 | \|', or the manual | |
174 | .I | |
175 | ld: the GNU linker | |
176 | \&, for full details on the command language and on other aspects of | |
177 | the GNU linker. | |
178 | ||
179 | This version of \c | |
180 | .B ld\c | |
181 | \& uses the general purpose BFD libraries | |
182 | to operate on object files. This allows \c | |
183 | .B ld\c | |
184 | \& to read, combine, and | |
185 | write object files in many different formats\(em\&for example, COFF or | |
186 | \c | |
187 | .B a.out\c | |
188 | \&. Different formats may be linked together to produce any | |
189 | available kind of object file. You can use `\|\c | |
190 | .B objdump \-i\c | |
191 | \|' to get a list of formats supported on various architectures; see | |
192 | .BR objdump ( 1 ). | |
193 | ||
194 | Aside from its flexibility, the GNU linker is more helpful than other | |
195 | linkers in providing diagnostic information. Many linkers abandon | |
196 | execution immediately upon encountering an error; whenever possible, | |
197 | \c | |
198 | .B ld\c | |
199 | \& continues executing, allowing you to identify other errors | |
200 | (or, in some cases, to get an output file in spite of the error). | |
201 | ||
202 | The GNU linker \c | |
203 | .B ld\c | |
204 | \& is meant to cover a broad range of situations, | |
205 | and to be as compatible as possible with other linkers. As a result, | |
206 | you have many choices to control its behavior through the command line, | |
207 | and through environment variables. | |
208 | ||
209 | .SH OPTIONS | |
210 | The plethora of command-line options may seem intimidating, but in | |
211 | actual practice few of them are used in any particular context. | |
212 | For instance, a frequent use of \c | |
213 | .B ld\c | |
214 | \& is to link standard Unix | |
215 | object files on a standard, supported Unix system. On such a system, to | |
216 | link a file \c | |
217 | .B hello.o\c | |
218 | \&: | |
219 | .sp | |
220 | .br | |
221 | $\ ld\ \-o\ output\ /lib/crt0.o\ hello.o\ \-lc | |
222 | .br | |
223 | .sp | |
224 | This tells \c | |
225 | .B ld\c | |
226 | \& to produce a file called \c | |
227 | .B output\c | |
228 | \& as the | |
229 | result of linking the file \c | |
230 | .B /lib/crt0.o\c | |
231 | \& with \c | |
232 | .B hello.o\c | |
233 | \& and | |
234 | the library \c | |
235 | .B libc.a\c | |
236 | \& which will come from the standard search | |
237 | directories. | |
238 | ||
239 | The command-line options to \c | |
240 | .B ld\c | |
241 | \& may be specified in any order, and | |
242 | may be repeated at will. For the most part, repeating an option with a | |
243 | different argument will either have no further effect, or override prior | |
244 | occurrences (those further to the left on the command line) of an | |
245 | option. | |
246 | ||
247 | The exceptions\(em\&which may meaningfully be used more than once\(em\&are | |
248 | \c | |
249 | .B \-A\c | |
250 | \&, \c | |
251 | .B \-b\c | |
252 | \& (or its synonym \c | |
253 | .B \-format\c | |
254 | \&), \c | |
255 | .B \-defsym\c | |
256 | \&, | |
257 | \c | |
258 | .B \-L\c | |
259 | \&, \c | |
260 | .B \-l\c | |
261 | \&, \c | |
262 | .B \-R\c | |
263 | \&, and \c | |
264 | .B \-u\c | |
265 | \&. | |
266 | ||
267 | The list of object files to be linked together, shown as \c | |
268 | .I objfile\c | |
269 | \&, | |
270 | may follow, precede, or be mixed in with command-line options; save that | |
271 | an \c | |
272 | .I objfile\c | |
273 | \& argument may not be placed between an option flag and | |
274 | its argument. | |
275 | ||
276 | Usually the linker is invoked with at least one object file, but other | |
277 | forms of binary input files can also be specified with \c | |
278 | .B \-l\c | |
279 | \&, | |
280 | \c | |
281 | .B \-R\c | |
282 | \&, and the script command language. If \c | |
283 | .I no\c | |
284 | \& binary input | |
285 | files at all are specified, the linker does not produce any output, and | |
286 | issues the message `\|\c | |
287 | .B No input files\c | |
288 | \|'. | |
289 | ||
290 | Option arguments must either follow the option letter without intervening | |
291 | whitespace, or be given as separate arguments immediately following the | |
292 | option that requires them. | |
293 | ||
294 | .TP | |
295 | .BI "-A" "architecture" | |
296 | In the current release of \c | |
297 | .B ld\c | |
298 | \&, this option is useful only for the | |
299 | Intel 960 family of architectures. In that \c | |
300 | .B ld\c | |
301 | \& configuration, the | |
302 | \c | |
303 | .I architecture\c | |
304 | \& argument is one of the two-letter names identifying | |
305 | members of the 960 family; the option specifies the desired output | |
306 | target, and warns of any incompatible instructions in the input files. | |
307 | It also modifies the linker's search strategy for archive libraries, to | |
308 | support the use of libraries specific to each particular | |
309 | architecture, by including in the search loop names suffixed with the | |
310 | string identifying the architecture. | |
311 | ||
312 | For example, if your \c | |
313 | .B ld\c | |
314 | \& command line included `\|\c | |
315 | .B \-ACA\c | |
316 | \|' as | |
317 | well as `\|\c | |
318 | .B \-ltry\c | |
319 | \|', the linker would look (in its built-in search | |
320 | paths, and in any paths you specify with \c | |
321 | .B \-L\c | |
322 | \&) for a library with | |
323 | the names | |
324 | .sp | |
325 | .br | |
326 | try | |
327 | .br | |
328 | libtry.a | |
329 | .br | |
330 | tryca | |
331 | .br | |
332 | libtryca.a | |
333 | .br | |
334 | .sp | |
335 | ||
336 | The first two possibilities would be considered in any event; the last | |
337 | two are due to the use of `\|\c | |
338 | .B \-ACA\c | |
339 | \|'. | |
340 | ||
341 | Future releases of \c | |
342 | .B ld\c | |
343 | \& may support similar functionality for | |
344 | other architecture families. | |
345 | ||
346 | You can meaningfully use \c | |
347 | .B \-A\c | |
348 | \& more than once on a command line, if | |
349 | an architecture family allows combination of target architectures; each | |
350 | use will add another pair of name variants to search for when \c | |
351 | .B \-l | |
352 | specifies a library. | |
353 | ||
354 | .TP | |
355 | .BI "\-b " "input-format" | |
356 | Specify the binary format for input object files that follow this option | |
357 | on the command line. You don't usually need to specify this, as | |
358 | \c | |
359 | .B ld\c | |
360 | \& is configured to expect as a default input format the most | |
361 | usual format on each machine. \c | |
362 | .I input-format\c | |
363 | \& is a text string, the | |
364 | name of a particular format supported by the BFD libraries. | |
365 | \c | |
366 | .B \-format \c | |
367 | .I input-format\c | |
368 | \&\c | |
369 | \& has the same effect, as does the script command | |
370 | .BR TARGET . | |
371 | ||
372 | You may want to use this option if you are linking files with an unusual | |
373 | binary format. You can also use \c | |
374 | .B \-b\c | |
375 | \& to switch formats explicitly (when | |
376 | linking object files of different formats), by including | |
377 | \c | |
378 | .B \-b \c | |
379 | .I input-format\c | |
380 | \&\c | |
381 | \& before each group of object files in a | |
382 | particular format. | |
383 | ||
384 | The default format is taken from the environment variable | |
385 | .B GNUTARGET\c | |
386 | \&. You can also define the input | |
387 | format from a script, using the command \c | |
388 | .B TARGET\c | |
389 | \&. | |
390 | ||
391 | .TP | |
392 | .B \-Bstatic | |
393 | Do not link against shared libraries. This is only meaningful on | |
394 | platforms for which shared libraries are supported. | |
395 | ||
396 | .TP | |
397 | .B \-Bdynamic | |
398 | Link against dynamic libraries. This is only meaningful on platforms | |
399 | for which shared libraries are supported. This option is normally the | |
400 | default on such platforms. | |
401 | ||
402 | .TP | |
403 | .B \-Bsymbolic | |
404 | When creating a shared library, bind references to global symbols to | |
405 | the definition within the shared library, if any. Normally, it is | |
406 | possible for a program linked against a shared library to override the | |
407 | definition within the shared library. This option is only meaningful | |
408 | on ELF platforms which support shared libraries. | |
409 | ||
410 | .TP | |
411 | .BI "\-c " "commandfile" | |
412 | Directs \c | |
413 | .B ld\c | |
414 | \& to read link commands from the file | |
415 | \c | |
416 | .I commandfile\c | |
417 | \&. These commands will completely override \c | |
418 | .B ld\c | |
419 | \&'s | |
420 | default link format (rather than adding to it); \c | |
421 | .I commandfile\c | |
422 | \& must | |
423 | specify everything necessary to describe the target format. | |
424 | ||
425 | ||
426 | You may also include a script of link commands directly in the command | |
427 | line by bracketing it between `\|\c | |
428 | .B {\c | |
429 | \|' and `\|\c | |
430 | .B }\c | |
431 | \|' characters. | |
432 | ||
433 | .TP | |
434 | .B \-\-cref | |
435 | Output a cross reference table. If a linker map file is being | |
436 | generated, the cross reference table is printed to the map file. | |
437 | Otherwise, it is printed on the standard output. | |
438 | ||
439 | .TP | |
440 | .B \-d | |
441 | .TP | |
442 | .B \-dc | |
443 | .TP | |
444 | .B \-dp | |
445 | These three options are equivalent; multiple forms are supported for | |
446 | compatibility with other linkers. Use any of them to make \c | |
447 | .B ld | |
448 | assign space to common symbols even if a relocatable output file is | |
449 | specified (\c | |
450 | .B \-r\c | |
451 | \&). The script command | |
452 | \c | |
453 | .B FORCE_COMMON_ALLOCATION\c | |
454 | \& has the same effect. | |
455 | ||
456 | .TP | |
457 | .BI "-defsym " "symbol" "\fR = \fP" expression | |
458 | Create a global symbol in the output file, containing the absolute | |
459 | address given by \c | |
460 | .I expression\c | |
461 | \&. You may use this option as many | |
462 | times as necessary to define multiple symbols in the command line. A | |
463 | limited form of arithmetic is supported for the \c | |
464 | .I expression\c | |
465 | \& in this | |
466 | context: you may give a hexadecimal constant or the name of an existing | |
467 | symbol, or use \c | |
468 | .B +\c | |
469 | \& and \c | |
470 | .B \-\c | |
471 | \& to add or subtract hexadecimal | |
472 | constants or symbols. If you need more elaborate expressions, consider | |
473 | using the linker command language from a script. | |
474 | ||
475 | .TP | |
476 | .B \-\-demangle | |
477 | .TP | |
478 | .B \-\-no\-demangle | |
479 | These options control whether to demangle symbol names in error | |
480 | messages and other output. When the linker is told to demangle, it | |
481 | tries to present symbol names in a readable fashion: it strips leading | |
482 | underscores if they are used by the object file format, and converts | |
483 | C++ mangled symbol names into user readable names. The linker will | |
484 | demangle by default unless the environment variable | |
485 | .B COLLECT_NO_DEMANGLE | |
486 | is set. These options may be used to override the default. | |
487 | ||
488 | .TP | |
489 | .BI "-e " "entry"\c | |
490 | \& | |
491 | Use \c | |
492 | .I entry\c | |
493 | \& as the explicit symbol for beginning execution of your | |
494 | program, rather than the default entry point. See the `\|\c | |
495 | .B ld\c | |
496 | \|' entry in `\|\c | |
497 | .B info\c | |
498 | \|' for a | |
499 | discussion of defaults and other ways of specifying the | |
500 | entry point. | |
501 | ||
502 | .TP | |
503 | .B \-embedded\-relocs | |
504 | This option is only meaningful when linking MIPS embedded PIC code, | |
505 | generated by the | |
506 | .B \-membedded\-pic | |
507 | option to the GNU compiler and assembler. It causes the linker to | |
508 | create a table which may be used at runtime to relocate any data which | |
509 | was statically initialized to pointer values. See the code in | |
510 | testsuite/ld-empic for details. | |
511 | ||
512 | .TP | |
513 | .B \-E | |
514 | .TP | |
515 | .B \-export\-dynamic | |
516 | When creating an ELF file, add all symbols to the dynamic symbol table. | |
517 | Normally, the dynamic symbol table contains only symbols which are used | |
518 | by a dynamic object. This option is needed for some uses of | |
519 | .I dlopen. | |
520 | ||
521 | .TP | |
522 | .BI "-f " "name" | |
523 | .TP | |
524 | .BI "--auxiliary " "name" | |
525 | When creating an ELF shared object, set the internal DT_AUXILIARY field | |
526 | to the specified name. This tells the dynamic linker that the symbol | |
527 | table of the shared object should be used as an auxiliary filter on the | |
528 | symbol table of the shared object | |
529 | .I name. | |
530 | ||
531 | .TP | |
532 | .BI "-F " "name" | |
533 | .TP | |
534 | .BI "--filter " "name" | |
535 | When creating an ELF shared object, set the internal DT_FILTER field to | |
536 | the specified name. This tells the dynamic linker that the symbol table | |
537 | of the shared object should be used as a filter on the symbol table of | |
538 | the shared object | |
539 | .I name. | |
540 | ||
541 | .TP | |
542 | .BI "\-format " "input\-format" | |
543 | Synonym for \c | |
544 | .B \-b\c | |
545 | \& \c | |
546 | .I input\-format\c | |
547 | \&. | |
548 | ||
549 | .TP | |
550 | .B \-g | |
551 | Accepted, but ignored; provided for compatibility with other tools. | |
552 | ||
553 | .TP | |
554 | .BI "\-G " "size"\c | |
555 | Set the maximum size of objects to be optimized using the GP register | |
556 | to | |
557 | .I size | |
558 | under MIPS ECOFF. Ignored for other object file formats. | |
559 | ||
560 | .TP | |
561 | .BI "-h " "name" | |
562 | .TP | |
563 | .BI "-soname " "name" | |
564 | When creating an ELF shared object, set the internal DT_SONAME field to | |
565 | the specified name. When an executable is linked with a shared object | |
566 | which has a DT_SONAME field, then when the executable is run the dynamic | |
567 | linker will attempt to load the shared object specified by the DT_SONAME | |
568 | field rather than the using the file name given to the linker. | |
569 | ||
570 | .TP | |
571 | .B \-\-help | |
572 | Print a summary of the command-line options on the standard output and exit. | |
573 | This option and | |
574 | .B \-\-version | |
575 | begin with two dashes instead of one | |
576 | for compatibility with other GNU programs. The other options start with | |
577 | only one dash for compatibility with other linkers. | |
578 | ||
579 | .TP | |
580 | .B \-i | |
581 | Perform an incremental link (same as option \c | |
582 | .B \-r\c | |
583 | \&). | |
584 | ||
585 | .TP | |
586 | .BI "\-l" "ar"\c | |
587 | \& | |
588 | Add an archive file \c | |
589 | .I ar\c | |
590 | \& to the list of files to link. This | |
591 | option may be used any number of times. \c | |
592 | .B ld\c | |
593 | \& will search its | |
594 | path-list for occurrences of \c | |
595 | .B lib\c | |
596 | .I ar\c | |
597 | \&.a\c | |
598 | \& for every \c | |
599 | .I ar | |
600 | specified. | |
601 | ||
602 | .TP | |
603 | .BI "\-L" "searchdir" | |
604 | This command adds path \c | |
605 | .I searchdir\c | |
606 | \& to the list of paths that | |
607 | \c | |
608 | .B ld\c | |
609 | \& will search for archive libraries. You may use this option | |
610 | any number of times. | |
611 | ||
612 | The default set of paths searched (without being specified with | |
613 | \c | |
614 | .B \-L\c | |
615 | \&) depends on what emulation mode \c | |
616 | .B ld\c | |
617 | \& is using, and in | |
618 | some cases also on how it was configured. The | |
619 | paths can also be specified in a link script with the \c | |
620 | .B SEARCH_DIR | |
621 | command. | |
622 | ||
623 | .TP | |
624 | .B \-M | |
625 | Print (to the standard output file) a link map\(em\&diagnostic information | |
626 | about where symbols are mapped by \c | |
627 | .B ld\c | |
628 | \&, and information on global | |
629 | common storage allocation. | |
630 | ||
631 | .TP | |
632 | .BI "\-Map " "mapfile"\c | |
633 | Print to the file | |
634 | .I mapfile | |
635 | a link map\(em\&diagnostic information | |
636 | about where symbols are mapped by \c | |
637 | .B ld\c | |
638 | \&, and information on global | |
639 | common storage allocation. | |
640 | ||
641 | .TP | |
642 | .BI "\-m " "emulation"\c | |
643 | Emulate the | |
644 | .I emulation | |
645 | linker. You can list the available emulations with the | |
646 | .I \-\-verbose | |
647 | or | |
648 | .I \-V | |
649 | options. This option overrides the compiled-in default, which is the | |
650 | system for which you configured | |
651 | .BR ld . | |
652 | ||
653 | .TP | |
654 | .B \-N | |
655 | specifies readable and writable \c | |
656 | .B text\c | |
657 | \& and \c | |
658 | .B data\c | |
659 | \& sections. If | |
660 | the output format supports Unix style magic numbers, the output is | |
661 | marked as \c | |
662 | .B OMAGIC\c | |
663 | \&. | |
664 | ||
665 | When you use the `\|\c | |
666 | .B \-N\c | |
667 | \&\|' option, the linker does not page-align the | |
668 | data segment. | |
669 | ||
670 | .TP | |
671 | .B \-n | |
672 | sets the text segment to be read only, and \c | |
673 | .B NMAGIC\c | |
674 | \& is written | |
675 | if possible. | |
676 | ||
677 | .TP | |
678 | .B \-noinhibit\-exec | |
679 | Normally, the linker will not produce an output file if it encounters | |
680 | errors during the link process. With this flag, you can specify that | |
681 | you wish the output file retained even after non-fatal errors. | |
682 | ||
683 | .TP | |
684 | .B \-no\-keep\-memory | |
685 | The linker normally optimizes for speed over memory usage by caching | |
686 | the symbol tables of input files in memory. This option tells the | |
687 | linker to instead optimize for memory usage, by rereading the symbol | |
688 | tables as necessary. This may be required if the linker runs out of | |
689 | memory space while linking a large executable. | |
690 | ||
691 | .TP | |
692 | .B \-no\-warn\-mismatch | |
693 | Normally the linker will give an error if you try to link together | |
694 | input files that are mismatched for some reason, perhaps because they | |
695 | have been compiled for different processors or for different | |
696 | endiannesses. This option tells the linker that it should silently | |
697 | permit such possible errors. This option should only be used with | |
698 | care, in cases when you have taken some special action that ensures | |
699 | that the linker errors are inappropriate. | |
700 | ||
701 | .TP | |
702 | .BI "\-o " "output" | |
703 | .I output\c | |
704 | \& is a name for the program produced by \c | |
705 | .B ld\c | |
706 | \&; if this | |
707 | option is not specified, the name `\|\c | |
708 | .B a.out\c | |
709 | \|' is used by default. The | |
710 | script command \c | |
711 | .B OUTPUT\c | |
712 | \& can also specify the output file name. | |
713 | ||
714 | .TP | |
715 | .BI "\-O" "level" | |
716 | Generate optimized output files. This might use significantly more | |
717 | time and therefore probably should be enabled only for generating the | |
718 | final binary. | |
719 | \c | |
720 | .I level\c | |
721 | \& is supposed to be a numeric value. Any value greater than zero enables | |
722 | the optimizations. | |
723 | ||
724 | .TP | |
725 | .BI "\-oformat " "output\-format" | |
726 | Specify the binary format for the output object file. | |
727 | You don't usually need to specify this, as | |
728 | \c | |
729 | .B ld\c | |
730 | \& is configured to produce as a default output format the most | |
731 | usual format on each machine. \c | |
732 | .I output-format\c | |
733 | \& is a text string, the | |
734 | name of a particular format supported by the BFD libraries. | |
735 | The script command | |
736 | .B OUTPUT_FORMAT | |
737 | can also specify the output format, but this option overrides it. | |
738 | ||
739 | .TP | |
740 | .BI "\-R " "filename" | |
741 | Read symbol names and their addresses from \c | |
742 | .I filename\c | |
743 | \&, but do not | |
744 | relocate it or include it in the output. This allows your output file | |
745 | to refer symbolically to absolute locations of memory defined in other | |
746 | programs. | |
747 | ||
748 | .TP | |
749 | .B \-relax | |
750 | An option with machine dependent effects. Currently this option is only | |
751 | supported on the H8/300. | |
752 | ||
753 | On some platforms, use this option to perform global optimizations that | |
754 | become possible when the linker resolves addressing in your program, such | |
755 | as relaxing address modes and synthesizing new instructions in the | |
756 | output object file. | |
757 | ||
758 | On platforms where this is not supported, `\|\c | |
759 | .B \-relax\c | |
760 | \&\|' is accepted, but has no effect. | |
761 | ||
762 | .TP | |
763 | .B \-r | |
764 | Generates relocatable output\(em\&i.e., generate an output file that can in | |
765 | turn serve as input to \c | |
766 | .B ld\c | |
767 | \&. This is often called \c | |
768 | .I partial | |
769 | linking\c | |
770 | \&. As a side effect, in environments that support standard Unix | |
771 | magic numbers, this option also sets the output file's magic number to | |
772 | \c | |
773 | .B OMAGIC\c | |
774 | \&. | |
775 | If this option is not specified, an absolute file is produced. When | |
776 | linking C++ programs, this option \c | |
777 | .I will not\c | |
778 | \& resolve references to | |
779 | constructors; \c | |
780 | .B \-Ur\c | |
781 | \& is an alternative. | |
782 | ||
783 | This option does the same as \c | |
784 | .B \-i\c | |
785 | \&. | |
786 | ||
787 | .TP | |
788 | .B \-rpath\ \fIdirectory | |
789 | Add a directory to the runtime library search path. This is used when | |
790 | linking an ELF executable with shared objects. All | |
791 | .B \-rpath | |
792 | arguments are concatenated and passed to the runtime linker, which uses | |
793 | them to locate shared objects at runtime. The | |
794 | .B \-rpath | |
795 | option is also used when locating shared objects which are needed by | |
796 | shared objects explicitly included in the link; see the description of | |
797 | the | |
798 | .B \-rpath\-link | |
799 | option. If | |
800 | .B \-rpath | |
801 | is not used when linking an ELF executable, the contents of the | |
802 | environment variable | |
803 | .B LD_RUN_PATH | |
804 | will be used if it is defined. | |
805 | ||
806 | The | |
807 | .B \-rpath | |
808 | option may also be used on SunOS. By default, on SunOS, the linker | |
809 | will form a runtime search path out of all the | |
810 | .B \-L | |
811 | options it is given. If a | |
812 | .B \-rpath | |
813 | option is used, the runtime search path will be formed exclusively | |
814 | using the | |
815 | .B \-rpath | |
816 | options, ignoring | |
817 | the | |
818 | .B \-L | |
819 | options. This can be useful when using gcc, which adds many | |
820 | .B \-L | |
821 | options which may be on NFS mounted filesystems. | |
822 | ||
823 | .TP | |
824 | .B \-rpath\-link\ \fIdirectory | |
825 | When using ELF or SunOS, one shared library may require another. This | |
826 | happens when an | |
827 | .B ld\ \-shared | |
828 | link includes a shared library as one of the input files. | |
829 | ||
830 | When the linker encounters such a dependency when doing a non-shared, | |
831 | non-relocateable link, it will automatically try to locate the required | |
832 | shared library and include it in the link, if it is not included | |
833 | explicitly. In such a case, the | |
834 | .B \-rpath\-link | |
835 | option specifies the first set of directories to search. The | |
836 | .B \-rpath\-link | |
837 | option may specify a sequence of directory names either by specifying | |
838 | a list of names separated by colons, or by appearing multiple times. | |
839 | ||
840 | If the required shared library is not found, the linker will issue a | |
841 | warning and continue with the link. | |
842 | ||
843 | .TP | |
844 | .B \-S | |
845 | Omits debugger symbol information (but not all symbols) from the output file. | |
846 | ||
847 | .TP | |
848 | .B \-s | |
849 | Omits all symbol information from the output file. | |
850 | ||
851 | .TP | |
852 | .B \-shared | |
853 | Create a shared library. This is currently only supported on ELF and | |
854 | SunOS platforms (on SunOS it is not required, as the linker will | |
855 | automatically create a shared library when there are undefined symbols | |
856 | and the | |
857 | .B \-e | |
858 | option is not used). | |
859 | ||
860 | .TP | |
861 | .B \-sort\-common | |
862 | Normally, when | |
863 | .B ld | |
864 | places the global common symbols in the appropriate output sections, | |
865 | it sorts them by size. First come all the one byte symbols, then all | |
866 | the two bytes, then all the four bytes, and then everything else. | |
867 | This is to prevent gaps between symbols due to | |
868 | alignment constraints. This option disables that sorting. | |
869 | ||
870 | .TP | |
871 | .B \-split\-by\-reloc\ \fIcount | |
872 | Trys to creates extra sections in the output file so that no single | |
873 | output section in the file contains more than | |
874 | .I count | |
875 | relocations. | |
876 | This is useful when generating huge relocatable for downloading into | |
877 | certain real time kernels with the COFF object file format; since COFF | |
878 | cannot represent more than 65535 relocations in a single section. | |
879 | Note that this will fail to work with object file formats which do not | |
880 | support arbitrary sections. The linker will not split up individual | |
881 | input sections for redistribution, so if a single input section | |
882 | contains more than | |
883 | .I count | |
884 | relocations one output section will contain that many relocations. | |
885 | ||
886 | .TP | |
887 | .B \-split\-by\-file | |
888 | Similar to | |
889 | .B \-split\-by\-reloc | |
890 | but creates a new output section for each input file. | |
891 | ||
892 | .TP | |
893 | .BI "\-Tbss " "org"\c | |
894 | .TP | |
895 | .BI "\-Tdata " "org"\c | |
896 | .TP | |
897 | .BI "\-Ttext " "org"\c | |
898 | Use \c | |
899 | .I org\c | |
900 | \& as the starting address for\(em\&respectively\(em\&the | |
901 | \c | |
902 | .B bss\c | |
903 | \&, \c | |
904 | .B data\c | |
905 | \&, or the \c | |
906 | .B text\c | |
907 | \& segment of the output file. | |
908 | \c | |
909 | .I org\c | |
910 | \& must be a hexadecimal integer. | |
911 | ||
912 | .TP | |
913 | .BI "\-T " "commandfile" | |
914 | Equivalent to \c | |
915 | .B \-c \c | |
916 | .I commandfile\c | |
917 | \&\c | |
918 | \&; supported for compatibility with | |
919 | other tools. | |
920 | ||
921 | .TP | |
922 | .B \-t | |
923 | Prints names of input files as \c | |
924 | .B ld\c | |
925 | \& processes them. | |
926 | ||
927 | .TP | |
928 | .BI "\-u " "sym" | |
929 | Forces \c | |
930 | .I sym\c | |
931 | \& to be entered in the output file as an undefined symbol. | |
932 | This may, for example, trigger linking of additional modules from | |
933 | standard libraries. \c | |
934 | .B \-u\c | |
935 | \& may be repeated with different option | |
936 | arguments to enter additional undefined symbols. | |
937 | ||
938 | .TP | |
939 | .B \-Ur | |
940 | For anything other than C++ programs, this option is equivalent to | |
941 | \c | |
942 | .B \-r\c | |
943 | \&: it generates relocatable output\(em\&i.e., an output file that can in | |
944 | turn serve as input to \c | |
945 | .B ld\c | |
946 | \&. When linking C++ programs, \c | |
947 | .B \-Ur | |
948 | .I will\c | |
949 | \& resolve references to constructors, unlike \c | |
950 | .B \-r\c | |
951 | \&. | |
952 | ||
953 | .TP | |
954 | .B \-\-verbose | |
955 | Display the version number for \c | |
956 | .B ld | |
957 | and list the supported emulations. | |
958 | Display which input files can and can not be opened. | |
959 | ||
960 | .TP | |
961 | .B \-v, \-V | |
962 | Display the version number for \c | |
963 | .B ld\c | |
964 | \&. | |
965 | The | |
966 | .B \-V | |
967 | option also lists the supported emulations. | |
968 | ||
969 | .TP | |
970 | .B \-\-version | |
971 | Display the version number for \c | |
972 | .B ld | |
973 | and exit. | |
974 | ||
975 | .TP | |
976 | .B \-warn\-common | |
977 | Warn when a common symbol is combined with another common symbol or with | |
978 | a symbol definition. Unix linkers allow this somewhat sloppy practice, | |
979 | but linkers on some other operating systems do not. This option allows | |
980 | you to find potential problems from combining global symbols. | |
981 | ||
982 | .TP | |
983 | .B \-warn\-constructors | |
984 | Warn if any global constructors are used. This is only useful for a | |
985 | few object file formats. For formats like COFF or ELF, the linker can | |
986 | not detect the use of global constructors. | |
987 | ||
988 | .TP | |
989 | .B \-warn\-multiple\-gp | |
990 | Warn if the output file requires multiple global-pointer values. This | |
991 | option is only meaningful for certain processors, such as the Alpha. | |
992 | ||
993 | .TP | |
994 | .B \-warn\-once | |
995 | Only warn once for each undefined symbol, rather than once per module | |
996 | which refers to it. | |
997 | ||
998 | .TP | |
999 | .B \-warn\-section\-align | |
1000 | Warn if the address of an output section is changed because of | |
1001 | alignment. Typically, the alignment will be set by an input section. | |
1002 | The address will only be changed if it not explicitly specified; that | |
1003 | is, if the SECTIONS command does not specify a start address for the | |
1004 | section. | |
1005 | ||
1006 | .TP | |
1007 | .B \-\-whole\-archive | |
1008 | For each archive mentioned on the command line after the | |
1009 | .B \-\-whole\-archive | |
1010 | option, include every object file in the archive in the link, rather | |
1011 | than searching the archive for the required object files. This is | |
1012 | normally used to turn an archive file into a shared library, forcing | |
1013 | every object to be included in the resulting shared library. | |
1014 | ||
1015 | .TP | |
1016 | .B \-\-no\-whole\-archive | |
1017 | Turn off the effect of the | |
1018 | .B \-\-whole\-archive | |
1019 | option for archives which appear later on the command line. | |
1020 | ||
1021 | .TP | |
1022 | .BI "--wrap " "symbol" | |
1023 | Use a wrapper function for | |
1024 | .I symbol. | |
1025 | Any undefined reference to | |
1026 | .I symbol | |
1027 | will be resolved to | |
1028 | .BI "__wrap_" "symbol". | |
1029 | Any undefined reference to | |
1030 | .BI "__real_" "symbol" | |
1031 | will be resolved to | |
1032 | .I symbol. | |
1033 | ||
1034 | .TP | |
1035 | .B \-X | |
1036 | Delete all temporary local symbols. For most targets, this is all local | |
1037 | symbols whose names begin with `\|\c | |
1038 | .B L\c | |
1039 | \|'. | |
1040 | ||
1041 | .TP | |
1042 | .B \-x | |
1043 | Delete all local symbols. | |
1044 | ||
1045 | .PP | |
1046 | ||
1047 | .SH ENVIRONMENT | |
1048 | \c | |
1049 | You can change the behavior of | |
1050 | .B ld\c | |
1051 | \& with the environment variable \c | |
1052 | .B GNUTARGET\c | |
1053 | \&. | |
1054 | ||
1055 | \c | |
1056 | .B GNUTARGET\c | |
1057 | \& determines the input-file object format if you don't | |
1058 | use \c | |
1059 | .B \-b\c | |
1060 | \& (or its synonym \c | |
1061 | .B \-format\c | |
1062 | \&). Its value should be one | |
1063 | of the BFD names for an input format. If there is no | |
1064 | \c | |
1065 | .B GNUTARGET\c | |
1066 | \& in the environment, \c | |
1067 | .B ld\c | |
1068 | \& uses the natural format | |
1069 | of the host. If \c | |
1070 | .B GNUTARGET\c | |
1071 | \& is set to \c | |
1072 | .B default\c | |
1073 | \& then BFD attempts to discover the | |
1074 | input format by examining binary input files; this method often | |
1075 | succeeds, but there are potential ambiguities, since there is no method | |
1076 | of ensuring that the magic number used to flag object-file formats is | |
1077 | unique. However, the configuration procedure for BFD on each system | |
1078 | places the conventional format for that system first in the search-list, | |
1079 | so ambiguities are resolved in favor of convention. | |
1080 | ||
1081 | .PP | |
1082 | ||
1083 | .SH "SEE ALSO" | |
1084 | ||
1085 | .BR objdump ( 1 ) | |
1086 | .br | |
1087 | .br | |
1088 | .RB "`\|" ld "\|' and `\|" binutils "\|'" | |
1089 | entries in | |
1090 | .B info\c | |
1091 | .br | |
1092 | .I | |
1093 | ld: the GNU linker\c | |
1094 | , Steve Chamberlain and Roland Pesch; | |
1095 | .I | |
1096 | The GNU Binary Utilities\c | |
1097 | , Roland H. Pesch. | |
1098 | ||
1099 | .SH COPYING | |
1100 | Copyright (c) 1991, 92, 93, 94, 95, 96, 97, 1998 Free Software Foundation, Inc. | |
1101 | .PP | |
1102 | Permission is granted to make and distribute verbatim copies of | |
1103 | this manual provided the copyright notice and this permission notice | |
1104 | are preserved on all copies. | |
1105 | .PP | |
1106 | Permission is granted to copy and distribute modified versions of this | |
1107 | manual under the conditions for verbatim copying, provided that the | |
1108 | entire resulting derived work is distributed under the terms of a | |
1109 | permission notice identical to this one. | |
1110 | .PP | |
1111 | Permission is granted to copy and distribute translations of this | |
1112 | manual into another language, under the above conditions for modified | |
1113 | versions, except that this permission notice may be included in | |
1114 | translations approved by the Free Software Foundation instead of in | |
1115 | the original English. |