ld/ld.1

   1 .\" Copyright (c) 1991, 92, 93, 94, 95, 96, 1997 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.  for a
 480 discussion of defaults and other ways of specifying the
 481 entry point.
 482
 483 .TP
 484 .B \-embedded\-relocs
 485 This option is only meaningful when linking MIPS embedded PIC code,
 486 generated by the
 487 .B \-membedded\-pic
 488 option to the GNU compiler and assembler.  It causes the linker to
 489 create a table which may be used at runtime to relocate any data which
 490 was statically initialized to pointer values.  See the code in
 491 testsuite/ld-empic for details.
 492
 493 .TP
 494 .B \-E
 495 .TP
 496 .B \-export\-dynamic
 497 When creating an ELF file, add all symbols to the dynamic symbol table.
 498 Normally, the dynamic symbol table contains only symbols which are used
 499 by a dynamic object.  This option is needed for some uses of
 500 .I dlopen.
 501
 502 .TP
 503 .BI "-f " "name"
 504 .TP
 505 .BI "--auxiliary " "name"
 506 When creating an ELF shared object, set the internal DT_AUXILIARY field
 507 to the specified name.  This tells the dynamic linker that the symbol
 508 table of the shared object should be used as an auxiliary filter on the
 509 symbol table of the shared object
 510 .I name.
 511
 512 .TP
 513 .BI "-F " "name"
 514 .TP
 515 .BI "--filter " "name"
 516 When creating an ELF shared object, set the internal DT_FILTER field to
 517 the specified name.  This tells the dynamic linker that the symbol table
 518 of the shared object should be used as a filter on the symbol table of
 519 the shared object
 520 .I name.
 521
 522 .TP
 523 .BI "\-format " "input\-format"
 524 Synonym for \c
 525 .B \-b\c
 526 \& \c
 527 .I input\-format\c
 528 \&.
 529
 530 .TP
 531 .B \-g
 532 Accepted, but ignored; provided for compatibility with other tools.
 533
 534 .TP
 535 .BI "\-G " "size"\c
 536 Set the maximum size of objects to be optimized using the GP register
 537 to
 538 .I size
 539 under MIPS ECOFF.  Ignored for other object file formats.
 540
 541 .TP
 542 .BI "-h " "name"
 543 .TP
 544 .BI "-soname " "name"
 545 When creating an ELF shared object, set the internal DT_SONAME field to
 546 the specified name.  When an executable is linked with a shared object
 547 which has a DT_SONAME field, then when the executable is run the dynamic
 548 linker will attempt to load the shared object specified by the DT_SONAME
 549 field rather than the using the file name given to the linker.
 550
 551 .TP
 552 .B \-\-help
 553 Print a summary of the command-line options on the standard output and exit.
 554 This option and
 555 .B \-\-version
 556 begin with two dashes instead of one
 557 for compatibility with other GNU programs.  The other options start with
 558 only one dash for compatibility with other linkers.
 559
 560 .TP
 561 .B \-i
 562 Perform an incremental link (same as option \c
 563 .B \-r\c
 564 \&).
 565
 566 .TP
 567 .BI "\-l" "ar"\c
 568 \&
 569 Add an archive file \c
 570 .I ar\c
 571 \& to the list of files to link.  This
 572 option may be used any number of times.  \c
 573 .B ld\c
 574 \& will search its
 575 path-list for occurrences of \c
 576 .B lib\c
 577 .I ar\c
 578 \&.a\c
 579 \& for every \c
 580 .I ar
 581 specified.
 582
 583 .TP
 584 .BI "\-L" "searchdir"
 585 This command adds path \c
 586 .I searchdir\c
 587 \& to the list of paths that
 588 \c
 589 .B ld\c
 590 \& will search for archive libraries.  You may use this option
 591 any number of times.
 592
 593 The default set of paths searched (without being specified with
 594 \c
 595 .B \-L\c
 596 \&) depends on what emulation mode \c
 597 .B ld\c
 598 \& is using, and in
 599 some cases also on how it was configured.    The
 600 paths can also be specified in a link script with the \c
 601 .B SEARCH_DIR
 602 command.
 603
 604 .TP
 605 .B \-M
 606 Print (to the standard output file) a link map\(em\&diagnostic information
 607 about where symbols are mapped by \c
 608 .B ld\c
 609 \&, and information on global
 610 common storage allocation.
 611
 612 .TP
 613 .BI "\-Map " "mapfile"\c
 614 Print to the file
 615 .I mapfile
 616 a link map\(em\&diagnostic information
 617 about where symbols are mapped by \c
 618 .B ld\c
 619 \&, and information on global
 620 common storage allocation.
 621
 622 .TP
 623 .BI "\-m " "emulation"\c
 624 Emulate the
 625 .I emulation
 626 linker.  You can list the available emulations with the
 627 .I \-\-verbose
 628 or
 629 .I \-V
 630 options.  This option overrides the compiled-in default, which is the
 631 system for which you configured
 632 .BR ld .
 633
 634 .TP
 635 .B \-N
 636 specifies readable and writable \c
 637 .B text\c
 638 \& and \c
 639 .B data\c
 640 \& sections. If
 641 the output format supports Unix style magic numbers, the output is
 642 marked as \c
 643 .B OMAGIC\c
 644 \&.
 645
 646 When you use the `\|\c
 647 .B \-N\c
 648 \&\|' option, the linker does not page-align the
 649 data segment.
 650
 651 .TP
 652 .B \-n
 653 sets the text segment to be read only, and \c
 654 .B NMAGIC\c
 655 \& is written
 656 if possible.
 657
 658 .TP
 659 .B \-noinhibit\-exec
 660 Normally, the linker will not produce an output file if it encounters
 661 errors during the link process.  With this flag, you can specify that
 662 you wish the output file retained even after non-fatal errors.
 663
 664 .TP
 665 .B \-no\-keep\-memory
 666 The linker normally optimizes for speed over memory usage by caching
 667 the symbol tables of input files in memory.  This option tells the
 668 linker to instead optimize for memory usage, by rereading the symbol
 669 tables as necessary.  This may be required if the linker runs out of
 670 memory space while linking a large executable.
 671
 672 .TP
 673 .B \-no\-warn\-mismatch
 674 Normally the linker will give an error if you try to link together
 675 input files that are mismatched for some reason, perhaps because they
 676 have been compiled for different processors or for different
 677 endiannesses.  This option tells the linker that it should silently
 678 permit such possible errors.  This option should only be used with
 679 care, in cases when you have taken some special action that ensures
 680 that the linker errors are inappropriate.
 681
 682 .TP
 683 .BI "\-o " "output"
 684 .I output\c
 685 \& is a name for the program produced by \c
 686 .B ld\c
 687 \&; if this
 688 option is not specified, the name `\|\c
 689 .B a.out\c
 690 \|' is used by default.  The
 691 script command \c
 692 .B OUTPUT\c
 693 \& can also specify the output file name.
 694
 695 .TP
 696 .BI "\-O" "level"
 697 Generate optimized output files.  This might use significantly more
 698 time and therefore probably should be enabled only for generating the
 699 final binary.
 700 \c
 701 .I level\c
 702 \& is supposed to be a numeric value.  Any value greater than zero enables
 703 the optimizations.
 704
 705 .TP
 706 .BI "\-oformat " "output\-format"
 707 Specify the binary format for the output object file.
 708 You don't usually need to specify this, as
 709 \c
 710 .B ld\c
 711 \& is configured to produce as a default output format the most
 712 usual format on each machine.  \c
 713 .I output-format\c
 714 \& is a text string, the
 715 name of a particular format supported by the BFD libraries.
 716 The script command
 717 .B OUTPUT_FORMAT
 718 can also specify the output format, but this option overrides it.
 719
 720 .TP
 721 .BI "\-R " "filename"
 722 Read symbol names and their addresses from \c
 723 .I filename\c
 724 \&, but do not
 725 relocate it or include it in the output.  This allows your output file
 726 to refer symbolically to absolute locations of memory defined in other
 727 programs.
 728
 729 .TP
 730 .B \-relax
 731 An option with machine dependent effects.  Currently this option is only
 732 supported on the H8/300.
 733
 734 On some platforms, use this option to perform global optimizations that
 735 become possible when the linker resolves addressing in your program, such
 736 as relaxing address modes and synthesizing new instructions in the
 737 output object file.
 738
 739 On platforms where this is not supported, `\|\c
 740 .B \-relax\c
 741 \&\|' is accepted, but has no effect.
 742
 743 .TP
 744 .B \-r
 745 Generates relocatable output\(em\&i.e., generate an output file that can in
 746 turn serve as input to \c
 747 .B ld\c
 748 \&.  This is often called \c
 749 .I partial
 750 linking\c
 751 \&.  As a side effect, in environments that support standard Unix
 752 magic numbers, this option also sets the output file's magic number to
 753 \c
 754 .B OMAGIC\c
 755 \&.
 756 If this option is not specified, an absolute file is produced.  When
 757 linking C++ programs, this option \c
 758 .I will not\c
 759 \& resolve references to
 760 constructors; \c
 761 .B \-Ur\c
 762 \& is an alternative.
 763
 764 This option does the same as \c
 765 .B \-i\c
 766 \&.
 767
 768 .TP
 769 .B \-rpath\ \fIdirectory
 770 Add a directory to the runtime library search path.  This is used when
 771 linking an ELF executable with shared objects.  All
 772 .B \-rpath
 773 arguments are concatenated and passed to the runtime linker, which uses
 774 them to locate shared objects at runtime.  The
 775 .B \-rpath
 776 option is also used when locating shared objects which are needed by
 777 shared objects explicitly included in the link; see the description of
 778 the
 779 .B \-rpath\-link
 780 option.  If
 781 .B \-rpath
 782 is not used when linking an ELF executable, the contents of the
 783 environment variable
 784 .B LD_RUN_PATH
 785 will be used if it is defined.
 786
 787 The
 788 .B \-rpath
 789 option may also be used on SunOS.  By default, on SunOS, the linker
 790 will form a runtime search patch out of all the
 791 .B \-L
 792 options it is given.  If a
 793 .B \-rpath
 794 option is used, the runtime search path will be formed exclusively
 795 using the
 796 .B \-rpath
 797 options, ignoring
 798 the
 799 .B \-L
 800 options.  This can be useful when using gcc, which adds many
 801 .B \-L
 802 options which may be on NFS mounted filesystems.
 803
 804 .TP
 805 .B \-rpath\-link\ \fIdirectory
 806 When using ELF or SunOS, one shared library may require another.  This
 807 happens when an
 808 .B ld\ \-shared
 809 link includes a shared library as one of the input files.
 810
 811 When the linker encounters such a dependency when doing a non-shared,
 812 non-relocateable link, it will automatically try to locate the required
 813 shared library and include it in the link, if it is not included
 814 explicitly.  In such a case, the
 815 .B \-rpath\-link
 816 option specifies the first set of directories to search.  The
 817 .B \-rpath\-link
 818 option may specify a sequence of directory names either by specifying
 819 a list of names separated by colons, or by appearing multiple times.
 820
 821 If the required shared library is not found, the linker will issue a
 822 warning and continue with the link.
 823
 824 .TP
 825 .B \-S
 826 Omits debugger symbol information (but not all symbols) from the output file.
 827
 828 .TP
 829 .B \-s
 830 Omits all symbol information from the output file.
 831
 832 .TP
 833 .B \-shared
 834 Create a shared library.  This is currently only supported on ELF and
 835 SunOS platforms (on SunOS it is not required, as the linker will
 836 automatically create a shared library when there are undefined symbols
 837 and the
 838 .B \-e
 839 option is not used).
 840
 841 .TP
 842 .B \-sort\-common
 843 Normally, when
 844 .B ld
 845 places the global common symbols in the appropriate output sections,
 846 it sorts them by size.  First come all the one byte symbols, then all
 847 the two bytes, then all the four bytes, and then everything else.
 848 This is to prevent gaps between symbols due to
 849 alignment constraints.  This option disables that sorting.
 850
 851 .TP
 852 .B \-split\-by\-reloc\ \fIcount
 853 Trys to creates extra sections in the output file so that no single
 854 output section in the file contains more than
 855 .I count
 856 relocations.
 857 This is useful when generating huge relocatable for downloading into
 858 certain real time kernels with the COFF object file format; since COFF
 859 cannot represent more than 65535 relocations in a single section.
 860 Note that this will fail to work with object file formats which do not
 861 support arbitrary sections.  The linker will not split up individual
 862 input sections for redistribution, so if a single input section
 863 contains more than
 864 .I count
 865 relocations one output section will contain that many relocations.
 866
 867 .TP
 868 .B \-split\-by\-file
 869 Similar to
 870 .B \-split\-by\-reloc
 871 but creates a new output section for each input file.
 872
 873 .TP
 874 .BI "\-Tbss " "org"\c
 875 .TP
 876 .BI "\-Tdata " "org"\c
 877 .TP
 878 .BI "\-Ttext " "org"\c
 879 Use \c
 880 .I org\c
 881 \& as the starting address for\(em\&respectively\(em\&the
 882 \c
 883 .B bss\c
 884 \&, \c
 885 .B data\c
 886 \&, or the \c
 887 .B text\c
 888 \& segment of the output file.
 889 \c
 890 .I textorg\c
 891 \& must be a hexadecimal integer.
 892
 893 .TP
 894 .BI "\-T " "commandfile"
 895 Equivalent to \c
 896 .B \-c \c
 897 .I commandfile\c
 898 \&\c
 899 \&; supported for compatibility with
 900 other tools.
 901
 902 .TP
 903 .B \-t
 904 Prints names of input files as \c
 905 .B ld\c
 906 \& processes them.
 907
 908 .TP
 909 .BI "\-u " "sym"
 910 Forces \c
 911 .I sym\c
 912 \& to be entered in the output file as an undefined symbol.
 913 This may, for example, trigger linking of additional modules from
 914 standard libraries.  \c
 915 .B \-u\c
 916 \& may be repeated with different option
 917 arguments to enter additional undefined symbols.
 918
 919 .TP
 920 .B \-Ur
 921 For anything other than C++ programs, this option is equivalent to
 922 \c
 923 .B \-r\c
 924 \&: it generates relocatable output\(em\&i.e., an output file that can in
 925 turn serve as input to \c
 926 .B ld\c
 927 \&.  When linking C++ programs, \c
 928 .B \-Ur
 929 .I will\c
 930 \& resolve references to constructors, unlike \c
 931 .B \-r\c
 932 \&.
 933
 934 .TP
 935 .B \-\-verbose
 936 Display the version number for \c
 937 .B ld
 938 and list the supported emulations.
 939 Display which input files can and can not be opened.
 940
 941 .TP
 942 .B \-v, \-V
 943 Display the version number for \c
 944 .B ld\c
 945 \&.
 946 The
 947 .B \-V
 948 option also lists the supported emulations.
 949
 950 .TP
 951 .B \-\-version
 952 Display the version number for \c
 953 .B ld
 954 and exit.
 955
 956 .TP
 957 .B \-warn\-common
 958 Warn when a common symbol is combined with another common symbol or with
 959 a symbol definition.  Unix linkers allow this somewhat sloppy practice,
 960 but linkers on some other operating systems do not.  This option allows
 961 you to find potential problems from combining global symbols.
 962
 963 .TP
 964 .B \-warn\-constructors
 965 Warn if any global constructors are used.  This is only useful for a
 966 few object file formats.  For formats like COFF or ELF, the linker can
 967 not detect the use of global constructors.
 968
 969 .TP
 970 .B \-warn\-multiple\-gp
 971 Warn if the output file requires multiple global-pointer values.  This
 972 option is only meaningful for certain processors, such as the Alpha.
 973
 974 .TP
 975 .B \-warn\-once
 976 Only warn once for each undefined symbol, rather than once per module
 977 which refers to it.
 978
 979 .TP
 980 .B \-warn\-section\-align
 981 Warn if the address of an output section is changed because of
 982 alignment.  Typically, the alignment will be set by an input section.
 983 The address will only be changed if it not explicitly specified; that
 984 is, if the SECTIONS command does not specify a start address for the
 985 section.
 986
 987 .TP
 988 .B \-\-whole\-archive
 989 For each archive mentioned on the command line after the
 990 .B \-\-whole\-archive
 991 option, include every object file in the archive in the link, rather
 992 than searching the archive for the required object files.  This is
 993 normally used to turn an archive file into a shared library, forcing
 994 every object to be included in the resulting shared library.
 995
 996 .TP
 997 .B \-\-no\-whole\-archive
 998 Turn off the effect of the
 999 .B \-\-whole\-archive
1000 option for archives which appear later on the command line.
1001
1002 .TP
1003 .BI "--wrap " "symbol"
1004 Use a wrapper function for
1005 .I symbol.
1006 Any undefined reference to
1007 .I symbol
1008 will be resolved to
1009 .BI "__wrap_" "symbol".
1010 Any undefined reference to
1011 .BI "__real_" "symbol"
1012 will be resolved to
1013 .I symbol.
1014
1015 .TP
1016 .B \-X
1017 Delete all temporary local symbols.  For most targets, this is all local
1018 symbols whose names begin with `\|\c
1019 .B L\c
1020 \|'.
1021
1022 .TP
1023 .B \-x
1024 Delete all local symbols.
1025
1026 .PP
1027
1028 .SH ENVIRONMENT
1029 \c
1030 You can change the behavior of
1031 .B ld\c
1032 \& with the environment variable \c
1033 .B GNUTARGET\c
1034 \&.
1035
1036 \c
1037 .B GNUTARGET\c
1038 \& determines the input-file object format if you don't
1039 use \c
1040 .B \-b\c
1041 \& (or its synonym \c
1042 .B \-format\c
1043 \&).  Its value should be one
1044 of the BFD names for an input format.  If there is no
1045 \c
1046 .B GNUTARGET\c
1047 \& in the environment, \c
1048 .B ld\c
1049 \& uses the natural format
1050 of the host. If \c
1051 .B GNUTARGET\c
1052 \& is set to \c
1053 .B default\c
1054 \& then BFD attempts to discover the
1055 input format by examining binary input files; this method often
1056 succeeds, but there are potential ambiguities, since there is no method
1057 of ensuring that the magic number used to flag object-file formats is
1058 unique.  However, the configuration procedure for BFD on each system
1059 places the conventional format for that system first in the search-list,
1060 so ambiguities are resolved in favor of convention.
1061
1062 .PP
1063
1064 .SH "SEE ALSO"
1065
1066 .BR objdump ( 1 )
1067 .br
1068 .br
1069 .RB "`\|" ld "\|' and `\|" binutils "\|'"
1070 entries in
1071 .B info\c
1072 .br
1073 .I
1074 ld: the GNU linker\c
1075 , Steve Chamberlain and Roland Pesch;
1076 .I
1077 The GNU Binary Utilities\c
1078 , Roland H. Pesch.
1079
1080 .SH COPYING
1081 Copyright (c) 1991, 1992 Free Software Foundation, Inc.
1082 .PP
1083 Permission is granted to make and distribute verbatim copies of
1084 this manual provided the copyright notice and this permission notice
1085 are preserved on all copies.
1086 .PP
1087 Permission is granted to copy and distribute modified versions of this
1088 manual under the conditions for verbatim copying, provided that the
1089 entire resulting derived work is distributed under the terms of a
1090 permission notice identical to this one.
1091 .PP
1092 Permission is granted to copy and distribute translations of this
1093 manual into another language, under the above conditions for modified
1094 versions, except that this permission notice may be included in
1095 translations approved by the Free Software Foundation instead of in
1096 the original English.