ld/ld.1

   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.