ld/ld.1

   1 .\" Copyright (c) 1991, 92, 93, 94, 1995 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 "[\|" \-d | \-dc | \-dp\c
  37 \|]
  38 .br
  39 .RB "[\|" "\-defsym\ "\c
  40 .I symbol\c
  41 \& = \c
  42 .I expression\c
  43 \&\|]
  44 .RB "[\|" "\-e\ "\c
  45 .I entry\c
  46 \&\|]
  47 .RB "[\|" \-embedded\-relocs "\|]"
  48 .RB "[\|" \-export\-dynamic "\|]"
  49 .RB "[\|" \-F "\|]"
  50 .RB "[\|" "\-F\ "\c
  51 .I format\c
  52 \&\|]
  53 .RB "[\|" "\-format\ "\c
  54 .I input-format\c
  55 \&\|]
  56 .RB "[\|" \-g "\|]"
  57 .RB "[\|" \-G
  58 .I size\c
  59 \&\|]
  60 .RB "[\|" \-\-help "\|]"
  61 .RB "[\|" \-i "\|]"
  62 .RB "[\|" \-l\c
  63 .I ar\c
  64 \&\|]
  65 .RB "[\|" \-L\c
  66 .I searchdir\c
  67 \&\|]
  68 .RB "[\|" \-M "\|]"
  69 .RB "[\|" \-Map
  70 .I mapfile\c
  71 \&\|]
  72 .RB "[\|" \-m
  73 .I emulation\c
  74 \&\|]
  75 .RB "[\|" \-n | \-N "\|]"
  76 .RB "[\|" \-noinhibit-exec "\|]"
  77 .RB "[\|" \-no\-keep\-memory "\|]"
  78 .RB "[\|" "\-oformat\ "\c
  79 .I output-format\c
  80 \&\|]
  81 .RB "[\|" "\-R\ "\c
  82 .I filename\c
  83 \&\|]
  84 .RB "[\|" \-relax "\|]"
  85 .RB "[\|" \-r | \-Ur "\|]"
  86 .RB "[\|" "\-rpath\ "\c
  87 .I directory\c
  88 \&\|]
  89 .RB "[\|" "\-rpath\-link\ "\c
  90 .I directory\c
  91 \&\|]
  92 .RB "[\|" \-S "\|]"
  93 .RB "[\|" \-s "\|]"
  94 .RB "[\|" \-shared "\|]"
  95 .RB "[\|" \-sort\-common "\|]"
  96 .RB "[\|" "\-split\-by\-reloc\ "\c
  97 .I count\c
  98 \&\|]
  99 .RB "[\|" \-split\-by\-file "\|]"
 100 .RB "[\|" "\-T\ "\c
 101 .I commandfile\c
 102 \&\|]
 103 .RB "[\|" "\-Ttext\ "\c
 104 .I textorg\c
 105 \&\|]
 106 .RB "[\|" "\-Tdata\ "\c
 107 .I dataorg\c
 108 \&\|]
 109 .RB "[\|" "\-Tbss\ "\c
 110 .I bssorg\c
 111 \&\|]
 112 .RB "[\|" \-t "\|]"
 113 .RB "[\|" "\-u\ "\c
 114 .I sym\c
 115 \&]
 116 .RB "[\|" \-V "\|]"
 117 .RB "[\|" \-v "\|]"
 118 .RB "[\|" \-\-verbose "\|]"
 119 .RB "[\|" \-\-version "\|]"
 120 .RB "[\|" \-warn\-common "\|]"
 121 .RB "[\|" \-warn\-constructors "\|]"
 122 .RB "[\|" \-warn\-once "\|]"
 123 .RB "[\|" \-\-whole\-archive "\|]"
 124 .RB "[\|" \-X "\|]"
 125 .RB "[\|" \-x "\|]"
 126 .ad b
 127 .hy 1
 128 .SH DESCRIPTION
 129 \c
 130 .B ld\c
 131 \& combines a number of object and archive files, relocates
 132 their data and ties up symbol references. Often the last step in
 133 building a new compiled program to run is a call to \c
 134 .B ld\c
 135 \&.
 136
 137 \c
 138 .B ld\c
 139 \& accepts Linker Command Language files
 140 to provide explicit and total control over the linking process.
 141 This man page does not describe the command language; see the `\|\c
 142 .B ld\c
 143 \|' entry in `\|\c
 144 .B info\c
 145 \|', or the manual
 146 .I
 147 ld: the GNU linker
 148 \&, for full details on the command language and on other aspects of
 149 the GNU linker.
 150
 151 This version of \c
 152 .B ld\c
 153 \& uses the general purpose BFD libraries
 154 to operate on object files. This allows \c
 155 .B ld\c
 156 \& to read, combine, and
 157 write object files in many different formats\(em\&for example, COFF or
 158 \c
 159 .B a.out\c
 160 \&.  Different formats may be linked together to produce any
 161 available kind of object file.  You can use `\|\c
 162 .B objdump \-i\c
 163 \|' to get a list of formats supported on various architectures; see
 164 .BR objdump ( 1 ).
 165
 166 Aside from its flexibility, the GNU linker is more helpful than other
 167 linkers in providing diagnostic information.  Many linkers abandon
 168 execution immediately upon encountering an error; whenever possible,
 169 \c
 170 .B ld\c
 171 \& continues executing, allowing you to identify other errors
 172 (or, in some cases, to get an output file in spite of the error).
 173
 174 The GNU linker \c
 175 .B ld\c
 176 \& is meant to cover a broad range of situations,
 177 and to be as compatible as possible with other linkers.  As a result,
 178 you have many choices to control its behavior through the command line,
 179 and through environment variables.
 180
 181 .SH OPTIONS
 182 The plethora of command-line options may seem intimidating, but in
 183 actual practice few of them are used in any particular context.
 184 For instance, a frequent use of \c
 185 .B ld\c
 186 \& is to link standard Unix
 187 object files on a standard, supported Unix system.  On such a system, to
 188 link a file \c
 189 .B hello.o\c
 190 \&:
 191 .sp
 192 .br
 193 $\ ld\ \-o\ output\ /lib/crt0.o\ hello.o\ \-lc
 194 .br
 195 .sp
 196 This tells \c
 197 .B ld\c
 198 \& to produce a file called \c
 199 .B output\c
 200 \& as the
 201 result of linking the file \c
 202 .B /lib/crt0.o\c
 203 \& with \c
 204 .B hello.o\c
 205 \& and
 206 the library \c
 207 .B libc.a\c
 208 \& which will come from the standard search
 209 directories.
 210
 211 The command-line options to \c
 212 .B ld\c
 213 \& may be specified in any order, and
 214 may be repeated at will.  For the most part, repeating an option with a
 215 different argument will either have no further effect, or override prior
 216 occurrences (those further to the left on the command line) of an
 217 option.
 218
 219 The exceptions\(em\&which may meaningfully be used more than once\(em\&are
 220 \c
 221 .B \-A\c
 222 \&, \c
 223 .B \-b\c
 224 \& (or its synonym \c
 225 .B \-format\c
 226 \&), \c
 227 .B \-defsym\c
 228 \&,
 229 \c
 230 .B \-L\c
 231 \&, \c
 232 .B \-l\c
 233 \&, \c
 234 .B \-R\c
 235 \&, and \c
 236 .B \-u\c
 237 \&.
 238
 239 The list of object files to be linked together, shown as \c
 240 .I objfile\c
 241 \&,
 242 may follow, precede, or be mixed in with command-line options; save that
 243 an \c
 244 .I objfile\c
 245 \& argument may not be placed between an option flag and
 246 its argument.
 247
 248 Usually the linker is invoked with at least one object file, but other
 249 forms of binary input files can also be specified with \c
 250 .B \-l\c
 251 \&,
 252 \c
 253 .B \-R\c
 254 \&, and the script command language.  If \c
 255 .I no\c
 256 \& binary input
 257 files at all are specified, the linker does not produce any output, and
 258 issues the message `\|\c
 259 .B No input files\c
 260 \|'.
 261
 262 Option arguments must either follow the option letter without intervening
 263 whitespace, or be given as separate arguments immediately following the
 264 option that requires them.
 265
 266 .TP
 267 .BI "-A" "architecture"
 268 In the current release of \c
 269 .B ld\c
 270 \&, this option is useful only for the
 271 Intel 960 family of architectures.  In that \c
 272 .B ld\c
 273 \& configuration, the
 274 \c
 275 .I architecture\c
 276 \& argument is one of the two-letter names identifying
 277 members of the 960 family; the option specifies the desired output
 278 target, and warns of any incompatible instructions in the input files.
 279 It also modifies the linker's search strategy for archive libraries, to
 280 support the use of libraries specific to each particular
 281 architecture, by including in the search loop names suffixed with the
 282 string identifying the architecture.
 283
 284 For example, if your \c
 285 .B ld\c
 286 \& command line included `\|\c
 287 .B \-ACA\c
 288 \|' as
 289 well as `\|\c
 290 .B \-ltry\c
 291 \|', the linker would look (in its built-in search
 292 paths, and in any paths you specify with \c
 293 .B \-L\c
 294 \&) for a library with
 295 the names
 296 .sp
 297 .br
 298 try
 299 .br
 300 libtry.a
 301 .br
 302 tryca
 303 .br
 304 libtryca.a
 305 .br
 306 .sp
 307
 308 The first two possibilities would be considered in any event; the last
 309 two are due to the use of `\|\c
 310 .B \-ACA\c
 311 \|'.
 312
 313 Future releases of \c
 314 .B ld\c
 315 \& may support similar functionality for
 316 other architecture families.
 317
 318 You can meaningfully use \c
 319 .B \-A\c
 320 \& more than once on a command line, if
 321 an architecture family allows combination of target architectures; each
 322 use will add another pair of name variants to search for when \c
 323 .B \-l
 324 specifies a library.
 325
 326 .TP
 327 .BI "\-b " "input-format"
 328 Specify the binary format for input object files that follow this option
 329 on the command line.  You don't usually need to specify this, as
 330 \c
 331 .B ld\c
 332 \& is configured to expect as a default input format the most
 333 usual format on each machine.  \c
 334 .I input-format\c
 335 \& is a text string, the
 336 name of a particular format supported by the BFD libraries.
 337 \c
 338 .B \-format \c
 339 .I input-format\c
 340 \&\c
 341 \& has the same effect, as does the script command
 342 .BR TARGET .
 343
 344 You may want to use this option if you are linking files with an unusual
 345 binary format.  You can also use \c
 346 .B \-b\c
 347 \& to switch formats explicitly (when
 348 linking object files of different formats), by including
 349 \c
 350 .B \-b \c
 351 .I input-format\c
 352 \&\c
 353 \& before each group of object files in a
 354 particular format.
 355
 356 The default format is taken from the environment variable
 357 .B GNUTARGET\c
 358 \&.  You can also define the input
 359 format from a script, using the command \c
 360 .B TARGET\c
 361 \&.
 362
 363 .TP
 364 .B \-Bstatic
 365 Do not link against shared libraries.  This is only meaningful on
 366 platforms for which shared libraries are supported.
 367
 368 .TP
 369 .B \-Bdynamic
 370 Link against dynamic libraries.  This is only meaningful on platforms
 371 for which shared libraries are supported.  This option is normally the
 372 default on such platforms.
 373
 374 .TP
 375 .B \-Bsymbolic
 376 When creating a shared library, bind references to global symbols to
 377 the definition within the shared library, if any.  Normally, it is
 378 possible for a program linked against a shared library to override the
 379 definition within the shared library.  This option is only meaningful
 380 on ELF platforms which support shared libraries.
 381
 382 .TP
 383 .BI "\-c " "commandfile"
 384 Directs \c
 385 .B ld\c
 386 \& to read link commands from the file
 387 \c
 388 .I commandfile\c
 389 \&.  These commands will completely override \c
 390 .B ld\c
 391 \&'s
 392 default link format (rather than adding to it); \c
 393 .I commandfile\c
 394 \& must
 395 specify everything necessary to describe the target format.
 396
 397
 398 You may also include a script of link commands directly in the command
 399 line by bracketing it between `\|\c
 400 .B {\c
 401 \|' and `\|\c
 402 .B }\c
 403 \|' characters.
 404
 405 .TP
 406 .B \-d
 407 .TP
 408 .B \-dc
 409 .TP
 410 .B \-dp
 411 These three options are equivalent; multiple forms are supported for
 412 compatibility with other linkers.  Use any of them to make \c
 413 .B ld
 414 assign space to common symbols even if a relocatable output file is
 415 specified (\c
 416 .B \-r\c
 417 \&).  The script command
 418 \c
 419 .B FORCE_COMMON_ALLOCATION\c
 420 \& has the same effect.
 421
 422 .TP
 423 .BI "-defsym " "symbol" "\fR = \fP" expression
 424 Create a global symbol in the output file, containing the absolute
 425 address given by \c
 426 .I expression\c
 427 \&.  You may use this option as many
 428 times as necessary to define multiple symbols in the command line.  A
 429 limited form of arithmetic is supported for the \c
 430 .I expression\c
 431 \& in this
 432 context: you may give a hexadecimal constant or the name of an existing
 433 symbol, or use \c
 434 .B +\c
 435 \& and \c
 436 .B \-\c
 437 \& to add or subtract hexadecimal
 438 constants or symbols.  If you need more elaborate expressions, consider
 439 using the linker command language from a script.
 440
 441 .TP
 442 .BI "-e " "entry"\c
 443 \&
 444 Use \c
 445 .I entry\c
 446 \& as the explicit symbol for beginning execution of your
 447 program, rather than the default entry point.  for a
 448 discussion of defaults and other ways of specifying the
 449 entry point.
 450
 451 .TP
 452 .B \-embedded\-relocs
 453 This option is only meaningful when linking MIPS embedded PIC code,
 454 generated by the
 455 .B \-membedded\-pic
 456 option to the GNU compiler and assembler.  It causes the linker to
 457 create a table which may be used at runtime to relocate any data which
 458 was statically initialized to pointer values.  See the code in
 459 testsuite/ld-empic for details.
 460
 461 .TP
 462 .B \-export\-dynamic
 463 When creating an ELF file, add all symbols to the dynamic symbol table.
 464 Normally, the dynamic symbol table contains only symbols which are used
 465 by a dynamic object.  This option is needed for some uses of
 466 .I dlopen.
 467
 468 .TP
 469 .B \-F
 470 .TP
 471 .BI "-F" "format"
 472 Some older linkers used this option throughout a compilation toolchain
 473 for specifying object-file format for both input and output object
 474 files.  \c
 475 .B ld\c
 476 \&'s mechanisms (the \c
 477 .B \-b\c
 478 \& or \c
 479 .B \-format\c
 480 \& options
 481 for input files, the \c
 482 .B TARGET\c
 483 \& command in linker scripts for output
 484 files, the \c
 485 .B GNUTARGET\c
 486 \& environment variable) are more flexible, but
 487 but it accepts (and ignores) the \c
 488 .B \-F\c
 489 \& option flag for compatibility
 490 with scripts written to call the old linker.
 491
 492 .TP
 493 .BI "\-format " "input\-format"
 494 Synonym for \c
 495 .B \-b\c
 496 \& \c
 497 .I input\-format\c
 498 \&.
 499
 500 .TP
 501 .B \-g
 502 Accepted, but ignored; provided for compatibility with other tools.
 503
 504 .TP
 505 .BI "\-G " "size"\c
 506 Set the maximum size of objects to be optimized using the GP register
 507 to
 508 .I size
 509 under MIPS ECOFF.  Ignored for other object file formats.
 510
 511 .TP
 512 .B \-\-help
 513 Print a summary of the command-line options on the standard output and exit.
 514 This option and
 515 .B \-\-version
 516 begin with two dashes instead of one
 517 for compatibility with other GNU programs.  The other options start with
 518 only one dash for compatibility with other linkers.
 519
 520 .TP
 521 .B \-i
 522 Perform an incremental link (same as option \c
 523 .B \-r\c
 524 \&).
 525
 526 .TP
 527 .BI "\-l" "ar"\c
 528 \&
 529 Add an archive file \c
 530 .I ar\c
 531 \& to the list of files to link.  This
 532 option may be used any number of times.  \c
 533 .B ld\c
 534 \& will search its
 535 path-list for occurrences of \c
 536 .B lib\c
 537 .I ar\c
 538 \&.a\c
 539 \& for every \c
 540 .I ar
 541 specified.
 542
 543 .TP
 544 .BI "\-L" "searchdir"
 545 This command adds path \c
 546 .I searchdir\c
 547 \& to the list of paths that
 548 \c
 549 .B ld\c
 550 \& will search for archive libraries.  You may use this option
 551 any number of times.
 552
 553 The default set of paths searched (without being specified with
 554 \c
 555 .B \-L\c
 556 \&) depends on what emulation mode \c
 557 .B ld\c
 558 \& is using, and in
 559 some cases also on how it was configured.    The
 560 paths can also be specified in a link script with the \c
 561 .B SEARCH_DIR
 562 command.
 563
 564 .TP
 565 .B \-M
 566 Print (to the standard output file) a link map\(em\&diagnostic information
 567 about where symbols are mapped by \c
 568 .B ld\c
 569 \&, and information on global
 570 common storage allocation.
 571
 572 .TP
 573 .BI "\-Map " "mapfile"\c
 574 Print to the file
 575 .I mapfile
 576 a link map\(em\&diagnostic information
 577 about where symbols are mapped by \c
 578 .B ld\c
 579 \&, and information on global
 580 common storage allocation.
 581
 582 .TP
 583 .BI "\-m " "emulation"\c
 584 Emulate the
 585 .I emulation
 586 linker.  You can list the available emulations with the
 587 .I \-\-verbose
 588 or
 589 .I \-V
 590 options.  This option overrides the compiled-in default, which is the
 591 system for which you configured
 592 .BR ld .
 593
 594 .TP
 595 .B \-N
 596 specifies readable and writable \c
 597 .B text\c
 598 \& and \c
 599 .B data\c
 600 \& sections. If
 601 the output format supports Unix style magic numbers, the output is
 602 marked as \c
 603 .B OMAGIC\c
 604 \&.
 605
 606 When you use the `\|\c
 607 .B \-N\c
 608 \&\|' option, the linker does not page-align the
 609 data segment.
 610
 611 .TP
 612 .B \-n
 613 sets the text segment to be read only, and \c
 614 .B NMAGIC\c
 615 \& is written
 616 if possible.
 617
 618 .TP
 619 .B \-noinhibit\-exec
 620 Normally, the linker will not produce an output file if it encounters
 621 errors during the link process.  With this flag, you can specify that
 622 you wish the output file retained even after non-fatal errors.
 623
 624 .TP
 625 .B \-no\-keep\-memory
 626 The linker normally optimizes for speed over memory usage by caching
 627 the symbol tables of input files in memory.  This option tells the
 628 linker to instead optimize for memory usage, by rereading the symbol
 629 tables as necessary.  This may be required if the linker runs out of
 630 memory space while linking a large executable.
 631
 632 .TP
 633 .BI "\-o " "output"
 634 .I output\c
 635 \& is a name for the program produced by \c
 636 .B ld\c
 637 \&; if this
 638 option is not specified, the name `\|\c
 639 .B a.out\c
 640 \|' is used by default.  The
 641 script command \c
 642 .B OUTPUT\c
 643 \& can also specify the output file name.
 644
 645 .TP
 646 .BI "\-oformat " "output\-format"
 647 Specify the binary format for the output object file.
 648 You don't usually need to specify this, as
 649 \c
 650 .B ld\c
 651 \& is configured to produce as a default output format the most
 652 usual format on each machine.  \c
 653 .I output-format\c
 654 \& is a text string, the
 655 name of a particular format supported by the BFD libraries.
 656 The script command
 657 .B OUTPUT_FORMAT
 658 can also specify the output format, but this option overrides it.
 659
 660 .TP
 661 .BI "\-R " "filename"
 662 Read symbol names and their addresses from \c
 663 .I filename\c
 664 \&, but do not
 665 relocate it or include it in the output.  This allows your output file
 666 to refer symbolically to absolute locations of memory defined in other
 667 programs.
 668
 669 .TP
 670 .B \-relax
 671 An option with machine dependent effects.  Currently this option is only
 672 supported on the H8/300.
 673
 674 On some platforms, use this option to perform global optimizations that
 675 become possible when the linker resolves addressing in your program, such
 676 as relaxing address modes and synthesizing new instructions in the
 677 output object file.
 678
 679 On platforms where this is not supported, `\|\c
 680 .B \-relax\c
 681 \&\|' is accepted, but has no effect.
 682
 683 .TP
 684 .B \-r
 685 Generates relocatable output\(em\&i.e., generate an output file that can in
 686 turn serve as input to \c
 687 .B ld\c
 688 \&.  This is often called \c
 689 .I partial
 690 linking\c
 691 \&.  As a side effect, in environments that support standard Unix
 692 magic numbers, this option also sets the output file's magic number to
 693 \c
 694 .B OMAGIC\c
 695 \&.
 696 If this option is not specified, an absolute file is produced.  When
 697 linking C++ programs, this option \c
 698 .I will not\c
 699 \& resolve references to
 700 constructors; \c
 701 .B \-Ur\c
 702 \& is an alternative.
 703
 704 This option does the same as \c
 705 .B \-i\c
 706 \&.
 707
 708 .TP
 709 .B \-rpath\ \fIdirectory
 710 Add a directory to the runtime library search path.  This is used when
 711 linking an ELF executable with shared objects.  All
 712 .B \-rpath
 713 arguments are concatenated and passed to the runtime linker, which uses
 714 them to locate shared objects at runtime.  The
 715 .B \-rpath
 716 option is also used when locating shared objects which are needed by
 717 shared objects explicitly included in the link; see the description of
 718 the
 719 .B \-rpath\-link
 720 option.  If
 721 .B \-rpath
 722 is not used when linking an ELF executable, the contents of the
 723 environment variable
 724 .B LD_RUN_PATH
 725 will be used if it is defined.
 726
 727 The
 728 .B \-rpath
 729 option may also be used on SunOS.  By default, on SunOS, the linker
 730 will form a runtime search patch out of all the
 731 .B \-L
 732 options it is given.  If a
 733 .B \-rpath
 734 option is used, the runtime search path will be formed exclusively
 735 using the
 736 .B \-rpath
 737 options, ignoring
 738 the
 739 .B \-L
 740 options.  This can be useful when using gcc, which adds many
 741 .B \-L
 742 options which may be on NFS mounted filesystems.
 743
 744 .TP
 745 .B \-rpath\-link\ \fIdirectory
 746 When using ELF or SunOS, one shared library may require another.  This
 747 happens when an
 748 .B ld\ \-shared
 749 link includes a shared library as one of the input files.
 750
 751 When the linker encounters such a dependency when doing a non-shared,
 752 non-relocateable link, it will automatically try to locate the required
 753 shared library and include it in the link, if it is not included
 754 explicitly.  In such a case, the
 755 .B \-rpath\-link
 756 option specifies the first set of directories to search.  The
 757 .B \-rpath\-link
 758 option may specify a sequence of directory names either by specifying
 759 a list of names separated by colons, or by appearing multiple times.
 760
 761 If the required shared library is not found, the linker will issue a
 762 warning and continue with the link.
 763
 764 .TP
 765 .B \-S
 766 Omits debugger symbol information (but not all symbols) from the output file.
 767
 768 .TP
 769 .B \-s
 770 Omits all symbol information from the output file.
 771
 772 .TP
 773 .B \-shared
 774 Create a shared library.  This is currently only supported on ELF and
 775 SunOS platforms (on SunOS it is not required, as the linker will
 776 automatically create a shared library when there are undefined symbols
 777 and the
 778 .B \-e
 779 option is not used).
 780
 781 .TP
 782 .B \-sort\-common
 783 Normally, when
 784 .B ld
 785 places the global common symbols in the appropriate output sections,
 786 it sorts them by size.  First come all the one byte symbols, then all
 787 the two bytes, then all the four bytes, and then everything else.
 788 This is to prevent gaps between symbols due to
 789 alignment constraints.  This option disables that sorting.
 790
 791 .TP
 792 .B \-split\-by\-reloc\ \fIcount
 793 Trys to creates extra sections in the output file so that no single
 794 output section in the file contains more than
 795 .I count
 796 relocations.
 797 This is useful when generating huge relocatable for downloading into
 798 certain real time kernels with the COFF object file format; since COFF
 799 cannot represent more than 65535 relocations in a single section.
 800 Note that this will fail to work with object file formats which do not
 801 support arbitrary sections.  The linker will not split up individual
 802 input sections for redistribution, so if a single input section
 803 contains more than
 804 .I count
 805 relocations one output section will contain that many relocations.
 806
 807 .TP
 808 .B \-split\-by\-file
 809 Similar to
 810 .B \-split\-by\-reloc
 811 but creates a new output section for each input file.
 812
 813 .TP
 814 .BI "\-Tbss " "org"\c
 815 .TP
 816 .BI "\-Tdata " "org"\c
 817 .TP
 818 .BI "\-Ttext " "org"\c
 819 Use \c
 820 .I org\c
 821 \& as the starting address for\(em\&respectively\(em\&the
 822 \c
 823 .B bss\c
 824 \&, \c
 825 .B data\c
 826 \&, or the \c
 827 .B text\c
 828 \& segment of the output file.
 829 \c
 830 .I textorg\c
 831 \& must be a hexadecimal integer.
 832
 833 .TP
 834 .BI "\-T " "commandfile"
 835 Equivalent to \c
 836 .B \-c \c
 837 .I commandfile\c
 838 \&\c
 839 \&; supported for compatibility with
 840 other tools.
 841
 842 .TP
 843 .B \-t
 844 Prints names of input files as \c
 845 .B ld\c
 846 \& processes them.
 847
 848 .TP
 849 .BI "\-u " "sym"
 850 Forces \c
 851 .I sym\c
 852 \& to be entered in the output file as an undefined symbol.
 853 This may, for example, trigger linking of additional modules from
 854 standard libraries.  \c
 855 .B \-u\c
 856 \& may be repeated with different option
 857 arguments to enter additional undefined symbols.
 858
 859 .TP
 860 .B \-Ur
 861 For anything other than C++ programs, this option is equivalent to
 862 \c
 863 .B \-r\c
 864 \&: it generates relocatable output\(em\&i.e., an output file that can in
 865 turn serve as input to \c
 866 .B ld\c
 867 \&.  When linking C++ programs, \c
 868 .B \-Ur
 869 .I will\c
 870 \& resolve references to constructors, unlike \c
 871 .B \-r\c
 872 \&.
 873
 874 .TP
 875 .B \-\-verbose
 876 Display the version number for \c
 877 .B ld
 878 and list the supported emulations.
 879 Display which input files can and can not be opened.
 880
 881 .TP
 882 .B \-v, \-V
 883 Display the version number for \c
 884 .B ld\c
 885 \&.
 886 The
 887 .B \-V
 888 option also lists the supported emulations.
 889
 890 .TP
 891 .B \-\-version
 892 Display the version number for \c
 893 .B ld
 894 and exit.
 895
 896 .TP
 897 .B \-warn\-common
 898 Warn when a common symbol is combined with another common symbol or with
 899 a symbol definition.  Unix linkers allow this somewhat sloppy practice,
 900 but linkers on some other operating systems do not.  This option allows
 901 you to find potential problems from combining global symbols.
 902
 903 .TP
 904 .B \-warn\-constructors
 905 Warn if any global constructors are used.  This is only useful for a
 906 few object file formats.  For formats like COFF or ELF, the linker can
 907 not detect the use of global constructors.
 908
 909 .TP
 910 .B \-warn\-once
 911 Only warn once for each undefined symbol, rather than once per module
 912 which refers to it.
 913
 914 .TP
 915 .B \-\-whole\-archive
 916 For each archive mentioned on the command line, include every object
 917 file in the archive in the link, rather than searching the archive for
 918 the required object files.  This is normally used to turn an archive
 919 file into a shared library, forcing every object to be included in the
 920 resulting shared library.
 921
 922 .TP
 923 .B \-X
 924 Delete all temporary local symbols.  For most targets, this is all local
 925 symbols whose names begin with `\|\c
 926 .B L\c
 927 \|'.
 928
 929 .TP
 930 .B \-x
 931 Delete all local symbols.
 932
 933 .PP
 934
 935 .SH ENVIRONMENT
 936 \c
 937 You can change the behavior of
 938 .B ld\c
 939 \& with the environment variable \c
 940 .B GNUTARGET\c
 941 \&.
 942
 943 \c
 944 .B GNUTARGET\c
 945 \& determines the input-file object format if you don't
 946 use \c
 947 .B \-b\c
 948 \& (or its synonym \c
 949 .B \-format\c
 950 \&).  Its value should be one
 951 of the BFD names for an input format.  If there is no
 952 \c
 953 .B GNUTARGET\c
 954 \& in the environment, \c
 955 .B ld\c
 956 \& uses the natural format
 957 of the host. If \c
 958 .B GNUTARGET\c
 959 \& is set to \c
 960 .B default\c
 961 \& then BFD attempts to discover the
 962 input format by examining binary input files; this method often
 963 succeeds, but there are potential ambiguities, since there is no method
 964 of ensuring that the magic number used to flag object-file formats is
 965 unique.  However, the configuration procedure for BFD on each system
 966 places the conventional format for that system first in the search-list,
 967 so ambiguities are resolved in favor of convention.
 968
 969 .PP
 970
 971 .SH "SEE ALSO"
 972
 973 .BR objdump ( 1 )
 974 .br
 975 .br
 976 .RB "`\|" ld "\|' and `\|" binutils "\|'"
 977 entries in
 978 .B info\c
 979 .br
 980 .I
 981 ld: the GNU linker\c
 982 , Steve Chamberlain and Roland Pesch;
 983 .I
 984 The GNU Binary Utilities\c
 985 , Roland H. Pesch.
 986
 987 .SH COPYING
 988 Copyright (c) 1991, 1992 Free Software Foundation, Inc.
 989 .PP
 990 Permission is granted to make and distribute verbatim copies of
 991 this manual provided the copyright notice and this permission notice
 992 are preserved on all copies.
 993 .PP
 994 Permission is granted to copy and distribute modified versions of this
 995 manual under the conditions for verbatim copying, provided that the
 996 entire resulting derived work is distributed under the terms of a
 997 permission notice identical to this one.
 998 .PP
 999 Permission is granted to copy and distribute translations of this
1000 manual into another language, under the above conditions for modified
1001 versions, except that this permission notice may be included in
1002 translations approved by the Free Software Foundation instead of in
1003 the original English.