ld/NEWS

   1 -*- text -*-
   2
   3 Changes in 2.33:
   4
   5 * Add target handlers for AArch64 for ELF GNU program properties.
   6
   7 * Add support for GNU_PROPERTY_AARCH64_FEATURE_1_BTI in ELF GNU program
   8   properties in the AArch64 ELF linker.
   9
  10 * Add support for GNU_PROPERTY_AARCH64_FEATURE_1_PAC in ELF GNU program
  11   properties in the AArch64 ELF linker.
  12
  13 * Add --force-bti for AArch64 to enable GNU_PROPERTY_AARCH64_FEATURE_1_BTI
  14   on output while warning about missing GNU_PROPERTY_AARCH64_FEATURE_1_BTI
  15   on inputs and use PLTs protected with BTI.
  16
  17 * Add --pac-plt for AArch64 to pick PAC enabled PLTs.
  18
  19 Changes in 2.32:
  20
  21 * Report property change in linker map file when merging GNU properties.
  22
  23 * Add support for the C-SKY processor series.
  24
  25 * -t now doesn't report members within archives, unless -t is given twice.
  26   A single -t is now more useful when generating a list of files that should be
  27   packaged for a linker bug report.  For example:
  28     gcc hello.c -save-temps -Wl,-t | xargs realpath | sort | uniq > files
  29     tar cJf test.tar.xz `cat files`
  30
  31 Changes in 2.31:
  32
  33 * Speed up direct linking with DLLs for Cygwin and Mingw targets.
  34
  35 * Add a configure option --enable-separate-code to decide whether
  36   -z separate-code should be enabled in ELF linker by default.  Default
  37   to yes for Linux/x86 targets.  Note that -z separate-code can increase
  38   disk and memory size.
  39
  40 Changes in 2.30:
  41
  42 * Add -z separate-code to generate separate code PT_LOAD segment.
  43
  44 * Add "-z undefs" command-line option as the inverse of the "-z defs" option.
  45
  46 * Add -z globalaudit command-line option to force audit libraries to be run
  47   for every dynamic object loaded by an executable - provided that the loader
  48   supports this functionality.
  49
  50 * Tighten linker script grammar around file name specifiers to prevent the use
  51   of SORT_BY_ALIGNMENT and SORT_BY_INIT_PRIORITY on filenames.  These would
  52   previously be accepted but had no effect.
  53
  54 * The EXCLUDE_FILE directive can now be placed within any SORT_* directive
  55   within input section lists.
  56
  57 Changes in 2.29:
  58
  59 * Support for -z shstk in the x86 ELF linker to generate
  60   GNU_PROPERTY_X86_FEATURE_1_SHSTK in ELF GNU program properties.
  61
  62 * Add support for GNU_PROPERTY_X86_FEATURE_1_SHSTK in ELF GNU program
  63   properties in the x86 ELF linker.
  64
  65 * Add support for GNU_PROPERTY_X86_FEATURE_1_IBT in ELF GNU program
  66   properties in the x86 ELF linker.
  67
  68 * Support for -z ibtplt in the x86 ELF linker to generate IBT-enabled
  69   PLT.
  70
  71 * Support for -z ibt in the x86 ELF linker to generate IBT-enabled
  72   PLT as well as GNU_PROPERTY_X86_FEATURE_1_IBT in ELF GNU program
  73   properties.
  74
  75 * Add support for ELF SHF_GNU_MBIND and PT_GNU_MBIND_XXX.
  76
  77 * Add support for ELF GNU program properties.
  78
  79 * Add support for the Texas Instruments PRU processor.
  80
  81 * When configuring for arc*-*-linux* targets the default linker emulation will
  82   change if --with-cpu=nps400 is used at configure time.
  83
  84 * Improve assignment of LMAs to orphan sections in some edge cases where a
  85   mixture of both AT>LMA_REGION and AT(LMA) are used.
  86
  87 * Orphan sections placed after an empty section that has an AT(LMA) will now
  88   take an load memory address starting from LMA.
  89
  90 * Section groups can now be resolved (the group deleted and the group members
  91   placed like normal sections) at partial link time either using the new linker
  92   option --force-group-allocation or by placing FORCE_GROUP_ALLOCATION into the
  93   linker script.
  94
  95 Changes in 2.28:
  96
  97 * The EXCLUDE_FILE linker script construct can now be applied outside of the
  98   section list in order for the exclusions to apply over all input sections in
  99   the list.
 100
 101 * Add support for the RISC-V architecture.
 102
 103 * The command-line option --no-eh-frame-hdr can now be used in ELF based
 104   linkers to disable the automatic generation of .eh_frame_hdr sections.
 105
 106 * Add --in-implib=<infile> to the ARM linker to enable specifying a set of
 107   Secure Gateway veneers that must exist in the output import library specified
 108   by --out-implib=<outfile> and the address they must have.  As such,
 109   --in-implib is only supported in combination with --cmse-implib.
 110
 111 * Extended the --out-implib=<file> option, previously restricted to x86 PE
 112   targets, to any ELF based target.  This allows the generation of an import
 113   library for an ELF executable, which can then be used by another application
 114   to link against the executable.
 115
 116 Changes in 2.27:
 117
 118 * Add a configure option --enable-relro to decide whether -z relro should
 119   be enabled in ELF linker by default.  Default to yes for all Linux
 120   targets except FRV, HPPA, IA64 and MIPS.  Note that -z relro can increase
 121   disk and memory size.
 122
 123 * Support for -z noreloc-overflow in the x86-64 ELF linker to disable
 124   relocation overflow check.
 125
 126 * Add -z common/-z nocommon options for ELF targets to control whether to
 127   convert common symbols to the STT_COMMON type during a relocatable link.
 128
 129 * Support for -z nodynamic-undefined-weak in the x86 ELF linker, which
 130   avoids dynamic relocations against undefined weak symbols in executable.
 131
 132 * The NOCROSSREFSTO command was added to the linker script language.
 133
 134 * Add --no-apply-dynamic-relocs to the AArch64 linker to do not apply link-time
 135   values for dynamic relocations.
 136
 137 Changes in 2.26:
 138
 139 * Add --fix-stm32l4xx-629360 to the ARM linker to enable a link-time
 140   workaround for a bug in the bus matrix / memory controller for some of
 141   the STM32 Cortex-M4 based products (STM32L4xx)
 142
 143 * Add a configure option --enable-compressed-debug-sections={all,ld} to
 144   decide whether DWARF debug sections should be compressed by default.
 145
 146 * Add support for the ARC EM/HS, and ARC600/700 architectures.
 147
 148 * Experimental support for linker garbage collection (--gc-sections)
 149   has been enabled for COFF and PE based targets.
 150
 151 * New command-line option for ELF targets to compress DWARF debug
 152   sections, --compress-debug-sections=[none|zlib|zlib-gnu|zlib-gabi].
 153
 154 * New command-line option, --orphan-handling=[place|warn|error|discard], to
 155   adjust how orphan sections are handled.  The default is 'place' which gives
 156   the current behaviour, 'warn' and 'error' issue a warning or error
 157   respectively when orphan sections are found, and 'discard' will discard all
 158   orphan sections.
 159
 160 * Add support for LLVM plugin.
 161
 162 * Add --print-memory-usage option to report memory blocks usage.
 163
 164 * Add --require-defined option, it's like --undefined except the new symbol
 165   must be defined by the end of the link.
 166
 167 Changes in 2.25:
 168
 169 * PE binaries now once again contain real timestamps by default.  To disable
 170   the inclusion of a timestamp in a PE binary, use the --no-insert-timestamp
 171   command-line option.
 172
 173 * Replace support for openrisc and or32 with support for or1k.
 174
 175 * Add support for the --build-id command-line option to COFF based targets.
 176
 177 * x86/x86_64 pe-coff now supports the --build-id option.
 178
 179 * Add support for the Andes NDS32.
 180
 181 Changes in 2.24:
 182
 183 * Add LOG2CEIL() builtin function to the linker script language
 184
 185 * Add support for the Texas Instruments MSP430X processor.
 186
 187 * Add support for Altera Nios II.
 188
 189 * Add support for the V850E3V5 architecture.
 190
 191 * Add support for the Imagination Technologies Meta processor.
 192
 193 * --enable-new-dtags no longer generates old dtags in addition to new dtags.
 194
 195 * Remove linker support for MIPS ECOFF targets.
 196
 197 * Add ALIGN_WITH_INPUT to the linker script language to force the alignment of
 198   an output section to use the maximum alignment of all its input sections.
 199
 200 Changes in 2.23:
 201
 202 * Enable compressed debug section feature for x86/x86_64 pe-coff.
 203
 204 * Add support for the 64-bit ARM architecture: AArch64.
 205
 206 * Added SORT_NONE to the linker script language to disable section sorting.
 207
 208 * Add a linker-provided symbol when producing ELF output, '__ehdr_start'
 209   to point to the ELF file header (and nearby program headers) in the
 210   program's memory image.
 211
 212 * Add support for S12X processor.
 213
 214 * Add support for the VLE extension to the PowerPC architecture.
 215
 216 * Add support for the Freescale XGATE architecture.
 217
 218 * Add option -f FILE on AIX (for response file).
 219
 220 * Add support for the Renesas RL78 architecture.
 221
 222 * Add support for the Adapteva EPIPHANY architecture.
 223
 224 Changes in 2.22:
 225
 226 * --copy-dt-needed-entries is no longer enabled by default.  Instead
 227   --no-copy-dt-needed-entries is the default.
 228
 229 * INPUT_SECTION_FLAGS has been added to the linker script language
 230   to allow selection of input sections by section header section flags.
 231
 232 * Add support for the Tilera TILEPro and TILE-Gx architectures.
 233
 234 * Added SORT_BY_INIT_PRIORITY to the linker script language to permit
 235   sorting sections by numerical value of the GCC init_priority attribute
 236   encoded in the section name.
 237
 238 Changes in 2.21:
 239
 240 * Linker script expression evaluation is somewhat more sane.  This may
 241   break scripts that depend on quirks of the old expression evaluation.
 242
 243 * Turn off underscoring for x86_64 PE+-COFF targets.  For old behavior the
 244   option --enable-leading-mingw64-underscores can be used on configure of
 245   bfd.
 246
 247 * Add support for the TMS320C6000 (TI C6X) processor family.
 248
 249 * --add-needed renamed to --copy-dt-needed-entries in order to avoid confusion
 250   with --as-needed option.
 251
 252 * Extend .def file syntax by '== <ID>' for imports and exports. This allows
 253   to alias the import/export table name written in PE image.
 254
 255 * Add --exclude-all-symbols option to PE based linkers.  This prevents all
 256   symbols from automatically being exported.
 257
 258 * Add support for the Renesas RX processor.
 259
 260 * Add support for alpha-vms target.
 261
 262 Changes in 2.20:
 263
 264 * GNU/Linux targets now support the STB_GNU_UNIQUE symbol binding.  This is a
 265   GNU extension to the standard set of ELF symbol bindings.  The binding will
 266   be passed on to the dynamic linker which will make sure that in the entire
 267   process there is just one symbol with the given name and type in use.
 268
 269 * PE targets now support a GNU extension to allow the alignment of common
 270   common symbols to be specified.  This support uses custom options in
 271   the .drectve section, which will be disregarded by the native tools.
 272
 273 * PE targets now add primitive support for ELF version scripts; symbols
 274   are not versioned, but the local and global symbol visibility directives
 275   are respected when filtering symbols in auto-export mode.
 276
 277 * New option --no-export-dynamic to undo the effect of the -E and
 278   --export-dynamic options.
 279
 280 * ELF: --warn-alternate-em option to warn if an object has alternate
 281   ELF machine code.
 282
 283 * New script function REGION_ALIAS to add alias names to memory regions.
 284
 285 * PE targets no longer make use of the long section names PE extension to
 286   the COFF format when generating executable images, by default.  The old
 287   (slightly non-conformant) behaviour can still be invoked by using the
 288   new '--enable-long-section-names' command-line option.  It is also enabled
 289   automatically in the presence of un-stripped debug information, as GDB
 290   needs to be able to find the debug info sections by their full names.
 291
 292 * For GNU/Linux systems the linker will now avoid processing any relocations
 293   made against symbols of the STT_GNU_IFUNC type and instead emit them into
 294   the resulting binary for processing by the loader.
 295
 296 * --as-needed now links in a dynamic library if it satisfies undefined
 297   symbols in regular objects, or in other dynamic libraries.  In the
 298   latter case the library is not linked if it is found in a DT_NEEDED
 299   entry of one of the libraries already linked.
 300
 301 * Add a new command-line option, -Ttext-segment ADDR, for ELF targets
 302   to set the address of the first byte of the text segment.
 303
 304 * Add support for Sunplus score architecture.
 305
 306 * Add new option --use-nul-prefixed-import-tables to ld for PE targets to
 307   allow fallback to old import table generation with null element prefix.
 308
 309 * Windows PE systems now support a new --exclude-modules-for-implib option,
 310   allowing users to partition object files and archive members between a DLL
 311   and its associated import library as they are generated during linking.
 312
 313 * Add support for Lattice Mico32 (lm32) architecture.
 314
 315 * Add CR16 ELF --embedded-relocs (used to embedded relocations into binaries
 316   for Embedded-PIC code) option.
 317
 318 * Add to the PE/PE+ targets the support of two different kinds of
 319   pseudo-relocations.  They can be selected by the switches
 320   --enable-runtime-pseudo-reloc-v1 and --enable-runtime-pseudo-reloc-v2.
 321   For the switch --enable-runtime-pseudo-reloc it uses for 32-bit
 322   runtime pseudo relocation version one, for 64-bit the version two.
 323
 324 Changes in 2.19:
 325
 326 * Linker scripts support a new INSERT command that makes it easier to
 327   augment the default script.
 328
 329 * Linker script input section filespecs may now specify a file within an
 330   archive by writing "archive:file".
 331
 332 * The --sort-common switch now has an optional argument which specifies the
 333   direction of sorting.
 334
 335 * The M68K linker now supports multiple GOT generation schemes controlled via
 336   the --got=<type> command-line option.
 337
 338 * The ARM EABI linker will now generate stubs for function calls to symbols
 339   that are too far away.  The placement of the stubs is controlled by a new
 340   linker command-line option: --stub-group-size=N.
 341
 342 Changes in 2.18:
 343
 344 * Linker sources now released under version 3 of the GNU General Public
 345   License.
 346
 347 * ELF: New --build-id option to generate a unique per-binary identifier
 348   embedded in a note section.
 349
 350 * Added support for National Semicondutor CompactRISC (ie CR16) target.
 351
 352 * -l:foo now searches the library path for a filename called foo,
 353   without converting it to libfoo.a or libfoo.so.
 354
 355 * Add a new command-line option '--default-script=FILE' or '-dT FILE'
 356   which specifies a replacement for the built in, default linker
 357   script.
 358
 359 * ELF: Add -Bsymbolic-functions, --dynamic-list-cpp-new, which puts C++
 360   operator new and delete on the dynamic list, and --dynamic-list-data,
 361   builtin list for --dynamic-list, which puts global data symbols on the
 362   dynamic list.
 363
 364 * Add support for x86_64 PE+ target.
 365
 366 * Add support for Score target.
 367
 368 * ELF: Add --dynamic-list option to specify a list of global symbols
 369   whose references shouldn't be bound to the definition within the
 370   shared library, or a list of symbols which should be added to the
 371   symbol table in the executable.
 372
 373 * The default output section LMA has changed for allocatable sections from
 374   being equal to VMA, to keeping the difference between LMA and VMA the same as
 375   the previous output section in the same region.  This is a more useful
 376   default when using overlays and other cases where you specify an LMA
 377   differing from the VMA for some sections.
 378
 379 * New switch: --print-gc-sections to list any sections removed by garabge
 380   collection.
 381
 382 * ARM: Added --vfp11-denorm-fix option to work around an erratum in current
 383   VFP11 coprocessors.
 384
 385 Changes in 2.17:
 386
 387 * Support for the Infineon XC16X has been added by KPIT Cummins Infosystems.
 388
 389 * Modify the Linux linker search order to better match ld.so search order.
 390   Look for DT_NEEDED libraries in paths specified by ld.so.conf before
 391   searching the default directories, rather than vice versa.
 392   Use $prefix/etc/ld.so.conf if it exists, otherwise /etc/ld.so.conf.
 393
 394 * PE-COFF: Forward exports from DLL's can now be specified in .def files
 395   passed directly to ld.
 396
 397 * Support for the Z80 processor family has been added.
 398
 399 * Add support for the "@<file>" syntax to the command line, so that extra
 400   switches can be read from <file>.
 401
 402 Changes in 2.16:
 403
 404 * Support for the R_ARM_V4BX relocation as defined in the ARM AAELF
 405   specification has been added via the --fix-v4bx command-line option.
 406
 407 * New linker script construct AS_NEEDED(), which sets the --as-needed flag
 408   for input files listed inside of it.
 409
 410 * A new command-line option, --sysroot, can be used to override the
 411   default sysroot location.  It only applies to toolchains that were
 412   configured using --with-sysroot.
 413
 414 * New linker script functions: ORIGIN() and LENGTH() which return information
 415   about a specified memory region.
 416
 417 * Port to MAXQ processor contributed by HCL Tech.
 418
 419 * Added SEGMENT_START to the linker script language to permit the user to
 420   override the base address for a segment from the command-line.
 421
 422 * ELF: --warn-shared-textrel option to warn if adding a DT_TEXTREL to a shared
 423   object.
 424
 425 * Added SORT_BY_NAME and SORT_BY_ALIGNMENT to the linker script
 426   language to permit sorting sections by section name or section
 427   maximum alignment.
 428
 429 * Added a new linker command-line switch, --sort-section name|alignment,
 430   to sort sections by section name or maximum alignment.
 431
 432 * ELF: --add-needed/--no-add-needed options to control if a DT_NEEDED tag
 433   should be added when a shared library comes from DT_NEEDED tags.
 434
 435 * Support for the crx-elf target added.
 436
 437 * Support for the sh-symbianelf target added.
 438
 439 * A new linker command-line switch has been added which allows the hash table
 440   size to be set to a suitable prime value near to its argument.  This switch
 441   is --hash-size=<NUMBER>.  Also if the switch --reduce-memory-overheads is
 442   used, and --hash-size has not been used, then the default value will be set
 443   to 1021.
 444
 445 * Linker map files are now generated with an O(N) algorithm for finding symbols
 446   that are defined in each section.  This uses about 40% more memory for
 447   symbols than the old O(N^2) algorithm.  You can use the new
 448   --reduce-memory-overheads option to select the old algorithm; this option
 449   might also be used in the future to select similar tradeoffs.
 450
 451 Changes in 2.15:
 452
 453 * ELF: --as-needed/--no-as-needed options to control if a DT_NEEDED tag should
 454   be added only when a shared library is referenced.
 455
 456 * PE: --large-address-aware option to indicate executables support virtual
 457   addresses greater than 2 gigabytes.
 458
 459 * DWARF 2 support for i386pe added.
 460
 461 * The linker script operator DEFINED() will now yield 1 only for a symbol that
 462   is defined before the statement where DEFINED is used.
 463
 464 * The MIPS --embedded-relocs (used to embed relocations into binaries for
 465   Embedded-PIC code) is deprecated and will be removed in a future release.
 466
 467 * cr16c support added by NSC.
 468
 469 * m32r Linux (ELF) support added by Renesas.
 470
 471 * Improved linker's handling of unresolved symbols.  The switch
 472   --unresolved-symbols=<method> has been added to tell the linker when it
 473   should report them and the switch --warn-unresolved-symbols has been added to
 474   make reports be issued as warning messages rather than errors.
 475
 476 Changes in 2.14:
 477
 478 * Added support for Xtensa architecture.
 479
 480 * Added --with-sysroot configure switch to specify a target system root, for
 481   linking against a target filesystem image.
 482
 483 * Added --accept-unknown-linker-format to restore old linker behaviour (pre
 484   2.14) of silently accepting and linking in any files in an unknown binary
 485   file format.
 486
 487 * Added --no-omagic to undo the effects of the -N option.
 488
 489 * Support for Texas Instruments TMS320C4x and TMS320C3x series of
 490   DSP's contributed by Michael Hayes and Svein E. Seldal.
 491
 492 * Added --with-lib-path configure switch to specify default value for
 493   LIB_PATH.
 494
 495 * ARM port to QNX operating system added by Graeme Peterson.
 496
 497 * IP2K support added by Denis Chertykov.
 498
 499 Changes in 2.13:
 500
 501 * Support for the Fujitsu FRV architecture added by Red Hat. Models for FR400
 502   and FR500 included.
 503
 504 Changes in version 2.13:
 505
 506 * DEC VAX ELF support, by Matt Thomas.
 507
 508 Changes in version 2.12:
 509
 510 * Support for Don Knuth's MMIX, by Hans-Peter Nilsson.
 511
 512 * Support for the OpenRISC 32-bit embedded processor by OpenCores.
 513
 514 * Support for -z nocopyreloc in the x86 ELF linker, which disables
 515   production of copy relocs.  Warning: using this option may result in
 516   non-sharable applications.
 517
 518 * Support for -z combreloc in the ELF linker, which puts dynamic
 519   relocations against the same symbol together, so that dynamic linker
 520   can use an one-entry symbol lookup cache.
 521
 522 * Support for ELF SHF_MERGE section merging, by Jakub Jelinek.
 523
 524 Changes in version 2.11:
 525
 526 * Support for AMD x86-64 architecture, by Jan Hubicka, SuSE Labs.
 527
 528 * Support added for eliminating duplicate DWARF2 debug information by
 529   having the compiler generate the information in sections called
 530   .gnu.linkonce.wi.XXXX where XXXX is a checksum for the contents.  The
 531   linker then merges these sections together into the normal .debug_info
 532   section.
 533
 534 * The native ELF linker now searches the directories in DT_RUNPATH or
 535   DT_RPATH of a shared library for shared libraries needed by it.
 536
 537 * TI C54x support, by Timothy Wall.
 538
 539 * Added command-line switch --section-start to set the start address of any
 540   specified section.
 541
 542 * Added ability to emit full relocation information in linked executables,
 543   enabled by --emit-relocs.  Some post-linkage optimization tools need
 544   this information in order to be able to correctly identify and perform
 545   symbol relative addressing in the event of changes in section contents
 546   (instructions being added or deleted, extending data sections, etc.)
 547
 548 * Support for i860, by Jason Eckhardt (preliminary, alpha quality).
 549
 550 * Support for CRIS (Axis Communications ETRAX series).
 551
 552 * Support for PDP-11 and 2.11BSD a.out format, by Lars Brinkhoff.
 553
 554 Changes in version 2.10:
 555
 556 * Added AT> to the linker script language to allow load-time allocation of
 557   sections into regions.
 558
 559 * Added garbage collection of unused sections, enabled by --gc-sections.
 560   It does require a bit of backend support; currently implemented are
 561   arm-elf, avr-elf, d10v-elf, fr30-elf, i386-elf, m32r-elf, m68k-elf,
 562   mcore-elf, mips-elf, mn10300-elf, ppc-elf, sh-elf, sparc-elf, and v850-elf.
 563   Others will ignore the option.
 564
 565 * Added SORT to the linker script language to permit sorting sections by file
 566   name or section name.
 567
 568 * Added EXTERN to the linker script language as an equivalent to the -u
 569   command-line option.
 570
 571 * Added ASSERT to the linker script language.
 572
 573 * Added EXCLUDE_FILE to the linker script language for further control over
 574   wildcard file names.
 575
 576 * Added -O option to optimize linker output (as of this writing, this only
 577   affects ELF shared library generation).
 578
 579 * The -e option now accepts a number as well as a symbol name.
 580
 581 * Added --no-undefined option to disallow undefined symbols when creating a
 582   shared library.
 583
 584 * The linker now issues a warning, not an error, for an undefined symbol when
 585   using -Bsymbolic; use the new --no-undefined option to get the old
 586   behaviour.
 587
 588 * Added --demangle and --no-demangle options.
 589
 590 Changes in version 2.9:
 591
 592 * Added SQUAD to the linker script language.
 593
 594 * New option --no-warn-mismatch.
 595
 596 * The MEMORY command now parses the attributes to determine where sections that
 597   are not placed in a specific memory region are placed.
 598
 599 Changes in version 2.8:
 600
 601 * Linker scripts may now contain shell wildcard characters for file and section
 602   names.
 603
 604 * The linker now supports symbol versions in ELF.
 605
 606 * The NOCROSSREFS command was added to the linker script language.
 607
 608 * The LOADADDR expression was added to the linker script language.
 609
 610 * MAX and MIN functions were added to the linker script language.
 611
 612 * The OVERLAY construct was added to the linker script language.
 613
 614 * New option --warn-section-align to warn when the address of an output section
 615   changes due to alignment of an input section.
 616
 617 * New options --filter/-F and --auxiliary/-f.
 618
 619 Changes in version 2.7:
 620
 621 * New option --cref to print out a cross reference table.
 622
 623 * New option --wrap SYMBOL.
 624
 625 * New option --no-whole-archive, to turn off the effect of --whole-archive.
 626
 627 * Input sections assigned to the output section /DISCARD/ in the linker script
 628   are not included in the output file.
 629
 630 * The SunOS and ELF linkers now merge stabs debugging information which uses
 631   the N_BINCL and N_EINCL stab types.  This reduces the amount of debugging
 632   information generated.
 633
 634 Changes in version 2.6:
 635
 636 * When an ELF section name is representable as a C identifier (this is not true
 637 of most ELF section names), the linker will automatically define symbols
 638 __start_SECNAME and __stop_SECNAME, where SECNAME is the section name, at the
 639 beginning and the end of the section.  This is used by glibc.
 640
 641   Addendum: Current versions of the linker (at least for version 2.18 onwards
 642 and possibly much earlier as well) place two restrictions on this feature:  The
 643 symbols are only implemented for orphaned sections, not for explicitly placed
 644 sections and they are PROVIDEd rather than being defined.
 645
 646 * When an ELF section named .gnu.warning is encountered in an input file, the
 647 contents of the section are displayed as an error message, and the section is
 648 not copied into the output file.  This is used by glibc.
 649
 650 * When an ELF section named .gnu.warning.SYMBOL is encountered in an input
 651 file, and the symbol SYMBOL is referenced by some object file, the contents of
 652 the section are displayed as an error message.  The section is not copied into
 653 the output file, unless doing a relocatable or shared link.  This is used by
 654 glibc.
 655
 656 * New options -split-by-reloc and -split-by-file.
 657
 658 * The linker now supports linking PIC compiled code on SPARC SunOS.  It can
 659 also create SPARC SunOS shared libraries, and, like the native SunOS linker,
 660 will do so whenever there is an undefined symbol in the link and neither the -e
 661 nor the -r option was used.
 662
 663 * The -rpath option may be used on SunOS to set the list of directories to be
 664 searched at run time.  This overrides the default of building the list from the
 665 -L options.
 666
 667 * The COFF linker now combines debugging information for structs, unions, and
 668 enums, so that even if the same type is defined in multiple input files it will
 669 only be defined once in the output file.  The --traditional-format switch will
 670 prevent this optimization.
 671
 672 Changes in version 2.5:
 673
 674 * The linker now supports linking against SunOS shared libraries.  It still can
 675 not link SunOS PIC (Position Independent Code) files, so it can not be used to
 676 generate shared libraries.
 677
 678 * The linker now supports linking against ELF shared libraries for the i386
 679 (UnixWare) and SPARC (Solaris).  It can also link ELF PIC files, and can be
 680 used to generate shared libraries.  Shared library generation is not well
 681 tested; please report any problems encountered.  The linker is now enabled for
 682 Solaris again.
 683
 684 * Eric Youngdale has contributed Linux support code, including linking against
 685 Linux a.out shared libraries.  The linker produces Linux QMAGIC binaries.
 686
 687 * The ELF backend has been converted to the new linker code.  To use the new
 688 ELF linker, each particular target requires a relocation function.  So far,
 689 this function has been written for i386 (UnixWare), SPARC (Solaris) MIPS (Irix
 690 5), and HPPA ELF targets.
 691
 692 * The -( (--start-group) and -) (--end-group) options have been added to
 693 support searching a group of archives as though they were a single archive.
 694 This can also be used in a linker script, as GROUP ( files ).
 695
 696 * When a file is named on the command line, and the linker does not recognize
 697 it as an object file, the linker will now treat the file as a linker script
 698 file.  A linker script named in this way augments, but does not replace, the
 699 default linker script.
 700
 701 * The -warn-once option was added.  It causes the linker to only warn once per
 702 undefined symbol, rather than once per reference.
 703
 704 * The COFF backend has been converted to the new linker code.  As with ELF, to
 705 use the new linker, each particular target requires a relocation function.  So
 706 far, this function has been written for the i386, m68k, a29k and SH targets.
 707
 708 * The -V flag was made a synonym for -v, for SVR4 compatibility.  The old -V
 709 behaviour is available via --verbose.
 710
 711 Changes in version 2.4:
 712
 713 * New linker code, by Steve Chamberlain and Ian Taylor.  For a.out and ecoff
 714   formats (so far), this should result in considerable savings in time
 715   and memory used while linking; slightly poorer performance than
 716   before for formats not converted yet.
 717
 718 * Command-line parsing is no longer done with flex.  This means
 719   oddball characters in filenames won't get treated as argument
 720   separators.
 721
 722 * HP-PA ELF support, by Jeff Law.  (No SOM support yet.)
 723
 724 * Mach i386 support, by David Mackenzie.
 725
 726 * Irix 4 shared libraries are now supported (Irix 5 uses ELF, and ELF shared
 727   libraries are not yet supported).
 728
 729 * COFF shared libraries (as on SCO) should work as well.
 730
 731 * The linker is disabled for Solaris.  (Actually, it was in 2.3 also, I just
 732   forgot to note it.)  Some of their C library routines don't work when
 733   statically linked, and the GNU linker doesn't support dynamic linking yet.
 734
 735 Changes in version 2.3:
 736
 737 * Weak symbols are now supported.
 738
 739 * ELF support has been added.  The linker has been bootstrapped on
 740   UnixWare and Solaris.
 741
 742 * Alpha OSF/1 support has been added (non dynamic linking only).
 743
 744 Changes in version 2.2:
 745
 746 * The `bfd' library has been updated to reduce a.out-format string
 747   table size.  The effect of this is that files linked from many input
 748   files with duplicate symbols (`-g' debugging records, or identical
 749   static symbols) should be much smaller.
 750
 751 Changes in version 2.1:
 752
 753 * The ld -ySYMBOL flag (to trace references to SYMBOL) is now implemented.
 754
 755 * There is now support for writing ECOFF files, so ld and the
 756   other utilities should work on Risc/Ultrix and Irix.
 757
 758 \f
 759 Copyright (C) 2012-2019 Free Software Foundation, Inc.
 760
 761 Copying and distribution of this file, with or without modification,
 762 are permitted in any medium without royalty provided the copyright
 763 notice and this notice are preserved.
 764
 765 Local variables:
 766 fill-column: 79
 767 End: