ld/ld.1

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