ld/NEWS

   1 -*- text -*-
   2
   3 * Add ELF linker command-line options, --export-dynamic-symbol and
   4   --export-dynamic-symbol-list, to make symbols dynamic.
   5
   6 * Add a configure option, --enable-textrel-check=[no|yes|warning|error],
   7   to decide what ELF linker should do by default with DT_TEXTREL in an
   8   executable or shared library.  Default to yes for Linux/x86 targets.
   9
  10 * The -Map=<filename> command line option has been extended so that if
  11   <filename> is a directory then <filename>/<output-filename>.map will be
  12   created.
  13
  14 * Add a command-line option for ELF linker, --warn-textrel, to warn that
  15   DT_TEXTREL is set in a position-independent executable or shared object.
  16
  17 * Add command-line options --enable-non-contiguous-regions and
  18   --enable-non-contiguous-regions-warnings.
  19
  20 * Add command-line option --imagic for the pdp11-aout target to output format
  21   IMAGIC (0411) for separate instruction and data spaces, and change the
  22   default format option for pdp11-aout to be --omagic.
  23
  24 * Relative pathnames in INPUT() and GROUP() directives in linker scripts are
  25   searched relative to the directory of the linker script before other search
  26   paths.
  27
  28 Changes in 2.34:
  29
  30 * The ld check for "PHDR segment not covered by LOAD segment" is more
  31   effective, catching cases that were wrongly allowed by previous versions of
  32   ld.  If you see this error it is likely you are linking with a bad linker
  33   script or the binary you are building is not intended to be loaded by a
  34   dynamic loader.  In the latter case --no-dynamic-linker is appropriate.
  35
  36 * cr16c support removed.
  37
  38 * Add support for z80-elf.
  39
  40 * Add support for relocation of each byte or word of multibyte value to Z80
  41   targets.
  42
  43 * Add support for Zilog eZ80 (both ADL and Z80 mode) and Zilog Z180 CPUs.
  44
  45 Changes in 2.33:
  46
  47 * Add command-line option --no-print-map-discarded.
  48
  49 * The Cortex-A53 Erratum 843419 workaround now supports a choice of which
  50   workaround to use.  The option --fix-cortex-a53-843419 now takes an
  51   optional argument --fix-cortex-a53-843419[=full|adr|adrp] which can be
  52   used to force a particular workaround to be used.  See --help for AArch64
  53   for more details.
  54
  55 * Add target handlers for AArch64 for ELF GNU program properties.
  56
  57 * Add support for GNU_PROPERTY_AARCH64_FEATURE_1_BTI in ELF GNU program
  58   properties in the AArch64 ELF linker.
  59
  60 * Add support for GNU_PROPERTY_AARCH64_FEATURE_1_PAC in ELF GNU program
  61   properties in the AArch64 ELF linker.
  62
  63 * Add -z force-bti for AArch64 to enable GNU_PROPERTY_AARCH64_FEATURE_1_BTI
  64   on output while warning about missing GNU_PROPERTY_AARCH64_FEATURE_1_BTI
  65   on inputs and use PLTs protected with BTI.
  66
  67 * Add -z pac-plt for AArch64 to pick PAC enabled PLTs.
  68
  69 Changes in 2.32:
  70
  71 * Report property change in linker map file when merging GNU properties.
  72
  73 * Add support for the C-SKY processor series.
  74
  75 * -t now doesn't report members within archives, unless -t is given twice.
  76   A single -t is now more useful when generating a list of files that should be
  77   packaged for a linker bug report.  For example:
  78     gcc hello.c -save-temps -Wl,-t | xargs realpath | sort | uniq > files
  79     tar cJf test.tar.xz `cat files`
  80
  81 Changes in 2.31:
  82
  83 * Speed up direct linking with DLLs for Cygwin and Mingw targets.
  84
  85 * Add a configure option --enable-separate-code to decide whether
  86   -z separate-code should be enabled in ELF linker by default.  Default
  87   to yes for Linux/x86 targets.  Note that -z separate-code can increase
  88   disk and memory size.
  89
  90 Changes in 2.30:
  91
  92 * Add -z separate-code to generate separate code PT_LOAD segment.
  93
  94 * Add "-z undefs" command-line option as the inverse of the "-z defs" option.
  95
  96 * Add -z globalaudit command-line option to force audit libraries to be run
  97   for every dynamic object loaded by an executable - provided that the loader
  98   supports this functionality.
  99
 100 * Tighten linker script grammar around file name specifiers to prevent the use
 101   of SORT_BY_ALIGNMENT and SORT_BY_INIT_PRIORITY on filenames.  These would
 102   previously be accepted but had no effect.
 103
 104 * The EXCLUDE_FILE directive can now be placed within any SORT_* directive
 105   within input section lists.
 106
 107 Changes in 2.29:
 108
 109 * Support for -z shstk in the x86 ELF linker to generate
 110   GNU_PROPERTY_X86_FEATURE_1_SHSTK in ELF GNU program properties.
 111
 112 * Add support for GNU_PROPERTY_X86_FEATURE_1_SHSTK in ELF GNU program
 113   properties in the x86 ELF linker.
 114
 115 * Add support for GNU_PROPERTY_X86_FEATURE_1_IBT in ELF GNU program
 116   properties in the x86 ELF linker.
 117
 118 * Support for -z ibtplt in the x86 ELF linker to generate IBT-enabled
 119   PLT.
 120
 121 * Support for -z ibt in the x86 ELF linker to generate IBT-enabled
 122   PLT as well as GNU_PROPERTY_X86_FEATURE_1_IBT in ELF GNU program
 123   properties.
 124
 125 * Add support for ELF SHF_GNU_MBIND and PT_GNU_MBIND_XXX.
 126
 127 * Add support for ELF GNU program properties.
 128
 129 * Add support for the Texas Instruments PRU processor.
 130
 131 * When configuring for arc*-*-linux* targets the default linker emulation will
 132   change if --with-cpu=nps400 is used at configure time.
 133
 134 * Improve assignment of LMAs to orphan sections in some edge cases where a
 135   mixture of both AT>LMA_REGION and AT(LMA) are used.
 136
 137 * Orphan sections placed after an empty section that has an AT(LMA) will now
 138   take an load memory address starting from LMA.
 139
 140 * Section groups can now be resolved (the group deleted and the group members
 141   placed like normal sections) at partial link time either using the new linker
 142   option --force-group-allocation or by placing FORCE_GROUP_ALLOCATION into the
 143   linker script.
 144
 145 Changes in 2.28:
 146
 147 * The EXCLUDE_FILE linker script construct can now be applied outside of the
 148   section list in order for the exclusions to apply over all input sections in
 149   the list.
 150
 151 * Add support for the RISC-V architecture.
 152
 153 * The command-line option --no-eh-frame-hdr can now be used in ELF based
 154   linkers to disable the automatic generation of .eh_frame_hdr sections.
 155
 156 * Add --in-implib=<infile> to the ARM linker to enable specifying a set of
 157   Secure Gateway veneers that must exist in the output import library specified
 158   by --out-implib=<outfile> and the address they must have.  As such,
 159   --in-implib is only supported in combination with --cmse-implib.
 160
 161 * Extended the --out-implib=<file> option, previously restricted to x86 PE
 162   targets, to any ELF based target.  This allows the generation of an import
 163   library for an ELF executable, which can then be used by another application
 164   to link against the executable.
 165
 166 Changes in 2.27:
 167
 168 * Add a configure option --enable-relro to decide whether -z relro should
 169   be enabled in ELF linker by default.  Default to yes for all Linux
 170   targets except FRV, HPPA, IA64 and MIPS.  Note that -z relro can increase
 171   disk and memory size.
 172
 173 * Support for -z noreloc-overflow in the x86-64 ELF linker to disable
 174   relocation overflow check.
 175
 176 * Add -z common/-z nocommon options for ELF targets to control whether to
 177   convert common symbols to the STT_COMMON type during a relocatable link.
 178
 179 * Support for -z nodynamic-undefined-weak in the x86 ELF linker, which
 180   avoids dynamic relocations against undefined weak symbols in executable.
 181
 182 * The NOCROSSREFSTO command was added to the linker script language.
 183
 184 * Add --no-apply-dynamic-relocs to the AArch64 linker to do not apply link-time
 185   values for dynamic relocations.
 186
 187 Changes in 2.26:
 188
 189 * Add --fix-stm32l4xx-629360 to the ARM linker to enable a link-time
 190   workaround for a bug in the bus matrix / memory controller for some of
 191   the STM32 Cortex-M4 based products (STM32L4xx)
 192
 193 * Add a configure option --enable-compressed-debug-sections={all,ld} to
 194   decide whether DWARF debug sections should be compressed by default.
 195
 196 * Add support for the ARC EM/HS, and ARC600/700 architectures.
 197
 198 * Experimental support for linker garbage collection (--gc-sections)
 199   has been enabled for COFF and PE based targets.
 200
 201 * New command-line option for ELF targets to compress DWARF debug
 202   sections, --compress-debug-sections=[none|zlib|zlib-gnu|zlib-gabi].
 203
 204 * New command-line option, --orphan-handling=[place|warn|error|discard], to
 205   adjust how orphan sections are handled.  The default is 'place' which gives
 206   the current behaviour, 'warn' and 'error' issue a warning or error
 207   respectively when orphan sections are found, and 'discard' will discard all
 208   orphan sections.
 209
 210 * Add support for LLVM plugin.
 211
 212 * Add --print-memory-usage option to report memory blocks usage.
 213
 214 * Add --require-defined option, it's like --undefined except the new symbol
 215   must be defined by the end of the link.
 216
 217 Changes in 2.25:
 218
 219 * PE binaries now once again contain real timestamps by default.  To disable
 220   the inclusion of a timestamp in a PE binary, use the --no-insert-timestamp
 221   command-line option.
 222
 223 * Replace support for openrisc and or32 with support for or1k.
 224
 225 * Add support for the --build-id command-line option to COFF based targets.
 226
 227 * x86/x86_64 pe-coff now supports the --build-id option.
 228
 229 * Add support for the Andes NDS32.
 230
 231 Changes in 2.24:
 232
 233 * Add LOG2CEIL() builtin function to the linker script language
 234
 235 * Add support for the Texas Instruments MSP430X processor.
 236
 237 * Add support for Altera Nios II.
 238
 239 * Add support for the V850E3V5 architecture.
 240
 241 * Add support for the Imagination Technologies Meta processor.
 242
 243 * --enable-new-dtags no longer generates old dtags in addition to new dtags.
 244
 245 * Remove linker support for MIPS ECOFF targets.
 246
 247 * Add ALIGN_WITH_INPUT to the linker script language to force the alignment of
 248   an output section to use the maximum alignment of all its input sections.
 249
 250 Changes in 2.23:
 251
 252 * Enable compressed debug section feature for x86/x86_64 pe-coff.
 253
 254 * Add support for the 64-bit ARM architecture: AArch64.
 255
 256 * Added SORT_NONE to the linker script language to disable section sorting.
 257
 258 * Add a linker-provided symbol when producing ELF output, '__ehdr_start'
 259   to point to the ELF file header (and nearby program headers) in the
 260   program's memory image.
 261
 262 * Add support for S12X processor.
 263
 264 * Add support for the VLE extension to the PowerPC architecture.
 265
 266 * Add support for the Freescale XGATE architecture.
 267
 268 * Add option -f FILE on AIX (for response file).
 269
 270 * Add support for the Renesas RL78 architecture.
 271
 272 * Add support for the Adapteva EPIPHANY architecture.
 273
 274 Changes in 2.22:
 275
 276 * --copy-dt-needed-entries is no longer enabled by default.  Instead
 277   --no-copy-dt-needed-entries is the default.
 278
 279 * INPUT_SECTION_FLAGS has been added to the linker script language
 280   to allow selection of input sections by section header section flags.
 281
 282 * Add support for the Tilera TILEPro and TILE-Gx architectures.
 283
 284 * Added SORT_BY_INIT_PRIORITY to the linker script language to permit
 285   sorting sections by numerical value of the GCC init_priority attribute
 286   encoded in the section name.
 287
 288 Changes in 2.21:
 289
 290 * Linker script expression evaluation is somewhat more sane.  This may
 291   break scripts that depend on quirks of the old expression evaluation.
 292
 293 * Turn off underscoring for x86_64 PE+-COFF targets.  For old behavior the
 294   option --enable-leading-mingw64-underscores can be used on configure of
 295   bfd.
 296
 297 * Add support for the TMS320C6000 (TI C6X) processor family.
 298
 299 * --add-needed renamed to --copy-dt-needed-entries in order to avoid confusion
 300   with --as-needed option.
 301
 302 * Extend .def file syntax by '== <ID>' for imports and exports. This allows
 303   to alias the import/export table name written in PE image.
 304
 305 * Add --exclude-all-symbols option to PE based linkers.  This prevents all
 306   symbols from automatically being exported.
 307
 308 * Add support for the Renesas RX processor.
 309
 310 * Add support for alpha-vms target.
 311
 312 Changes in 2.20:
 313
 314 * GNU/Linux targets now support the STB_GNU_UNIQUE symbol binding.  This is a
 315   GNU extension to the standard set of ELF symbol bindings.  The binding will
 316   be passed on to the dynamic linker which will make sure that in the entire
 317   process there is just one symbol with the given name and type in use.
 318
 319 * PE targets now support a GNU extension to allow the alignment of common
 320   common symbols to be specified.  This support uses custom options in
 321   the .drectve section, which will be disregarded by the native tools.
 322
 323 * PE targets now add primitive support for ELF version scripts; symbols
 324   are not versioned, but the local and global symbol visibility directives
 325   are respected when filtering symbols in auto-export mode.
 326
 327 * New option --no-export-dynamic to undo the effect of the -E and
 328   --export-dynamic options.
 329
 330 * ELF: --warn-alternate-em option to warn if an object has alternate
 331   ELF machine code.
 332
 333 * New script function REGION_ALIAS to add alias names to memory regions.
 334
 335 * PE targets no longer make use of the long section names PE extension to
 336   the COFF format when generating executable images, by default.  The old
 337   (slightly non-conformant) behaviour can still be invoked by using the
 338   new '--enable-long-section-names' command-line option.  It is also enabled
 339   automatically in the presence of un-stripped debug information, as GDB
 340   needs to be able to find the debug info sections by their full names.
 341
 342 * For GNU/Linux systems the linker will now avoid processing any relocations
 343   made against symbols of the STT_GNU_IFUNC type and instead emit them into
 344   the resulting binary for processing by the loader.
 345
 346 * --as-needed now links in a dynamic library if it satisfies undefined
 347   symbols in regular objects, or in other dynamic libraries.  In the
 348   latter case the library is not linked if it is found in a DT_NEEDED
 349   entry of one of the libraries already linked.
 350
 351 * Add a new command-line option, -Ttext-segment ADDR, for ELF targets
 352   to set the address of the first byte of the text segment.
 353
 354 * Add support for Sunplus score architecture.
 355
 356 * Add new option --use-nul-prefixed-import-tables to ld for PE targets to
 357   allow fallback to old import table generation with null element prefix.
 358
 359 * Windows PE systems now support a new --exclude-modules-for-implib option,
 360   allowing users to partition object files and archive members between a DLL
 361   and its associated import library as they are generated during linking.
 362
 363 * Add support for Lattice Mico32 (lm32) architecture.
 364
 365 * Add CR16 ELF --embedded-relocs (used to embedded relocations into binaries
 366   for Embedded-PIC code) option.
 367
 368 * Add to the PE/PE+ targets the support of two different kinds of
 369   pseudo-relocations.  They can be selected by the switches
 370   --enable-runtime-pseudo-reloc-v1 and --enable-runtime-pseudo-reloc-v2.
 371   For the switch --enable-runtime-pseudo-reloc it uses for 32-bit
 372   runtime pseudo relocation version one, for 64-bit the version two.
 373
 374 Changes in 2.19:
 375
 376 * Linker scripts support a new INSERT command that makes it easier to
 377   augment the default script.
 378
 379 * Linker script input section filespecs may now specify a file within an
 380   archive by writing "archive:file".
 381
 382 * The --sort-common switch now has an optional argument which specifies the
 383   direction of sorting.
 384
 385 * The M68K linker now supports multiple GOT generation schemes controlled via
 386   the --got=<type> command-line option.
 387
 388 * The ARM EABI linker will now generate stubs for function calls to symbols
 389   that are too far away.  The placement of the stubs is controlled by a new
 390   linker command-line option: --stub-group-size=N.
 391
 392 Changes in 2.18:
 393
 394 * Linker sources now released under version 3 of the GNU General Public
 395   License.
 396
 397 * ELF: New --build-id option to generate a unique per-binary identifier
 398   embedded in a note section.
 399
 400 * Added support for National Semicondutor CompactRISC (ie CR16) target.
 401
 402 * -l:foo now searches the library path for a filename called foo,
 403   without converting it to libfoo.a or libfoo.so.
 404
 405 * Add a new command-line option '--default-script=FILE' or '-dT FILE'
 406   which specifies a replacement for the built in, default linker
 407   script.
 408
 409 * ELF: Add -Bsymbolic-functions, --dynamic-list-cpp-new, which puts C++
 410   operator new and delete on the dynamic list, and --dynamic-list-data,
 411   builtin list for --dynamic-list, which puts global data symbols on the
 412   dynamic list.
 413
 414 * Add support for x86_64 PE+ target.
 415
 416 * Add support for Score target.
 417
 418 * ELF: Add --dynamic-list option to specify a list of global symbols
 419   whose references shouldn't be bound to the definition within the
 420   shared library, or a list of symbols which should be added to the
 421   symbol table in the executable.
 422
 423 * The default output section LMA has changed for allocatable sections from
 424   being equal to VMA, to keeping the difference between LMA and VMA the same as
 425   the previous output section in the same region.  This is a more useful
 426   default when using overlays and other cases where you specify an LMA
 427   differing from the VMA for some sections.
 428
 429 * New switch: --print-gc-sections to list any sections removed by garabge
 430   collection.
 431
 432 * ARM: Added --vfp11-denorm-fix option to work around an erratum in current
 433   VFP11 coprocessors.
 434
 435 Changes in 2.17:
 436
 437 * Support for the Infineon XC16X has been added by KPIT Cummins Infosystems.
 438
 439 * Modify the Linux linker search order to better match ld.so search order.
 440   Look for DT_NEEDED libraries in paths specified by ld.so.conf before
 441   searching the default directories, rather than vice versa.
 442   Use $prefix/etc/ld.so.conf if it exists, otherwise /etc/ld.so.conf.
 443
 444 * PE-COFF: Forward exports from DLL's can now be specified in .def files
 445   passed directly to ld.
 446
 447 * Support for the Z80 processor family has been added.
 448
 449 * Add support for the "@<file>" syntax to the command line, so that extra
 450   switches can be read from <file>.
 451
 452 Changes in 2.16:
 453
 454 * Support for the R_ARM_V4BX relocation as defined in the ARM AAELF
 455   specification has been added via the --fix-v4bx command-line option.
 456
 457 * New linker script construct AS_NEEDED(), which sets the --as-needed flag
 458   for input files listed inside of it.
 459
 460 * A new command-line option, --sysroot, can be used to override the
 461   default sysroot location.  It only applies to toolchains that were
 462   configured using --with-sysroot.
 463
 464 * New linker script functions: ORIGIN() and LENGTH() which return information
 465   about a specified memory region.
 466
 467 * Port to MAXQ processor contributed by HCL Tech.
 468
 469 * Added SEGMENT_START to the linker script language to permit the user to
 470   override the base address for a segment from the command-line.
 471
 472 * ELF: --warn-shared-textrel option to warn if adding a DT_TEXTREL to a shared
 473   object.
 474
 475 * Added SORT_BY_NAME and SORT_BY_ALIGNMENT to the linker script
 476   language to permit sorting sections by section name or section
 477   maximum alignment.
 478
 479 * Added a new linker command-line switch, --sort-section name|alignment,
 480   to sort sections by section name or maximum alignment.
 481
 482 * ELF: --add-needed/--no-add-needed options to control if a DT_NEEDED tag
 483   should be added when a shared library comes from DT_NEEDED tags.
 484
 485 * Support for the crx-elf target added.
 486
 487 * Support for the sh-symbianelf target added.
 488
 489 * A new linker command-line switch has been added which allows the hash table
 490   size to be set to a suitable prime value near to its argument.  This switch
 491   is --hash-size=<NUMBER>.  Also if the switch --reduce-memory-overheads is
 492   used, and --hash-size has not been used, then the default value will be set
 493   to 1021.
 494
 495 * Linker map files are now generated with an O(N) algorithm for finding symbols
 496   that are defined in each section.  This uses about 40% more memory for
 497   symbols than the old O(N^2) algorithm.  You can use the new
 498   --reduce-memory-overheads option to select the old algorithm; this option
 499   might also be used in the future to select similar tradeoffs.
 500
 501 Changes in 2.15:
 502
 503 * ELF: --as-needed/--no-as-needed options to control if a DT_NEEDED tag should
 504   be added only when a shared library is referenced.
 505
 506 * PE: --large-address-aware option to indicate executables support virtual
 507   addresses greater than 2 gigabytes.
 508
 509 * DWARF 2 support for i386pe added.
 510
 511 * The linker script operator DEFINED() will now yield 1 only for a symbol that
 512   is defined before the statement where DEFINED is used.
 513
 514 * The MIPS --embedded-relocs (used to embed relocations into binaries for
 515   Embedded-PIC code) is deprecated and will be removed in a future release.
 516
 517 * cr16c support added by NSC.
 518
 519 * m32r Linux (ELF) support added by Renesas.
 520
 521 * Improved linker's handling of unresolved symbols.  The switch
 522   --unresolved-symbols=<method> has been added to tell the linker when it
 523   should report them and the switch --warn-unresolved-symbols has been added to
 524   make reports be issued as warning messages rather than errors.
 525
 526 Changes in 2.14:
 527
 528 * Added support for Xtensa architecture.
 529
 530 * Added --with-sysroot configure switch to specify a target system root, for
 531   linking against a target filesystem image.
 532
 533 * Added --accept-unknown-linker-format to restore old linker behaviour (pre
 534   2.14) of silently accepting and linking in any files in an unknown binary
 535   file format.
 536
 537 * Added --no-omagic to undo the effects of the -N option.
 538
 539 * Support for Texas Instruments TMS320C4x and TMS320C3x series of
 540   DSP's contributed by Michael Hayes and Svein E. Seldal.
 541
 542 * Added --with-lib-path configure switch to specify default value for
 543   LIB_PATH.
 544
 545 * ARM port to QNX operating system added by Graeme Peterson.
 546
 547 * IP2K support added by Denis Chertykov.
 548
 549 Changes in 2.13:
 550
 551 * Support for the Fujitsu FRV architecture added by Red Hat. Models for FR400
 552   and FR500 included.
 553
 554 Changes in version 2.13:
 555
 556 * DEC VAX ELF support, by Matt Thomas.
 557
 558 Changes in version 2.12:
 559
 560 * Support for Don Knuth's MMIX, by Hans-Peter Nilsson.
 561
 562 * Support for the OpenRISC 32-bit embedded processor by OpenCores.
 563
 564 * Support for -z nocopyreloc in the x86 ELF linker, which disables
 565   production of copy relocs.  Warning: using this option may result in
 566   non-sharable applications.
 567
 568 * Support for -z combreloc in the ELF linker, which puts dynamic
 569   relocations against the same symbol together, so that dynamic linker
 570   can use an one-entry symbol lookup cache.
 571
 572 * Support for ELF SHF_MERGE section merging, by Jakub Jelinek.
 573
 574 Changes in version 2.11:
 575
 576 * Support for AMD x86-64 architecture, by Jan Hubicka, SuSE Labs.
 577
 578 * Support added for eliminating duplicate DWARF2 debug information by
 579   having the compiler generate the information in sections called
 580   .gnu.linkonce.wi.XXXX where XXXX is a checksum for the contents.  The
 581   linker then merges these sections together into the normal .debug_info
 582   section.
 583
 584 * The native ELF linker now searches the directories in DT_RUNPATH or
 585   DT_RPATH of a shared library for shared libraries needed by it.
 586
 587 * TI C54x support, by Timothy Wall.
 588
 589 * Added command-line switch --section-start to set the start address of any
 590   specified section.
 591
 592 * Added ability to emit full relocation information in linked executables,
 593   enabled by --emit-relocs.  Some post-linkage optimization tools need
 594   this information in order to be able to correctly identify and perform
 595   symbol relative addressing in the event of changes in section contents
 596   (instructions being added or deleted, extending data sections, etc.)
 597
 598 * Support for i860, by Jason Eckhardt (preliminary, alpha quality).
 599
 600 * Support for CRIS (Axis Communications ETRAX series).
 601
 602 * Support for PDP-11 and 2.11BSD a.out format, by Lars Brinkhoff.
 603
 604 Changes in version 2.10:
 605
 606 * Added AT> to the linker script language to allow load-time allocation of
 607   sections into regions.
 608
 609 * Added garbage collection of unused sections, enabled by --gc-sections.
 610   It does require a bit of backend support; currently implemented are
 611   arm-elf, avr-elf, d10v-elf, fr30-elf, i386-elf, m32r-elf, m68k-elf,
 612   mcore-elf, mips-elf, mn10300-elf, ppc-elf, sh-elf, sparc-elf, and v850-elf.
 613   Others will ignore the option.
 614
 615 * Added SORT to the linker script language to permit sorting sections by file
 616   name or section name.
 617
 618 * Added EXTERN to the linker script language as an equivalent to the -u
 619   command-line option.
 620
 621 * Added ASSERT to the linker script language.
 622
 623 * Added EXCLUDE_FILE to the linker script language for further control over
 624   wildcard file names.
 625
 626 * Added -O option to optimize linker output (as of this writing, this only
 627   affects ELF shared library generation).
 628
 629 * The -e option now accepts a number as well as a symbol name.
 630
 631 * Added --no-undefined option to disallow undefined symbols when creating a
 632   shared library.
 633
 634 * The linker now issues a warning, not an error, for an undefined symbol when
 635   using -Bsymbolic; use the new --no-undefined option to get the old
 636   behaviour.
 637
 638 * Added --demangle and --no-demangle options.
 639
 640 Changes in version 2.9:
 641
 642 * Added SQUAD to the linker script language.
 643
 644 * New option --no-warn-mismatch.
 645
 646 * The MEMORY command now parses the attributes to determine where sections that
 647   are not placed in a specific memory region are placed.
 648
 649 Changes in version 2.8:
 650
 651 * Linker scripts may now contain shell wildcard characters for file and section
 652   names.
 653
 654 * The linker now supports symbol versions in ELF.
 655
 656 * The NOCROSSREFS command was added to the linker script language.
 657
 658 * The LOADADDR expression was added to the linker script language.
 659
 660 * MAX and MIN functions were added to the linker script language.
 661
 662 * The OVERLAY construct was added to the linker script language.
 663
 664 * New option --warn-section-align to warn when the address of an output section
 665   changes due to alignment of an input section.
 666
 667 * New options --filter/-F and --auxiliary/-f.
 668
 669 Changes in version 2.7:
 670
 671 * New option --cref to print out a cross reference table.
 672
 673 * New option --wrap SYMBOL.
 674
 675 * New option --no-whole-archive, to turn off the effect of --whole-archive.
 676
 677 * Input sections assigned to the output section /DISCARD/ in the linker script
 678   are not included in the output file.
 679
 680 * The SunOS and ELF linkers now merge stabs debugging information which uses
 681   the N_BINCL and N_EINCL stab types.  This reduces the amount of debugging
 682   information generated.
 683
 684 Changes in version 2.6:
 685
 686 * When an ELF section name is representable as a C identifier (this is not true
 687 of most ELF section names), the linker will automatically define symbols
 688 __start_SECNAME and __stop_SECNAME, where SECNAME is the section name, at the
 689 beginning and the end of the section.  This is used by glibc.
 690
 691   Addendum: Current versions of the linker (at least for version 2.18 onwards
 692 and possibly much earlier as well) place two restrictions on this feature:  The
 693 symbols are only implemented for orphaned sections, not for explicitly placed
 694 sections and they are PROVIDEd rather than being defined.
 695
 696 * When an ELF section named .gnu.warning is encountered in an input file, the
 697 contents of the section are displayed as an error message, and the section is
 698 not copied into the output file.  This is used by glibc.
 699
 700 * When an ELF section named .gnu.warning.SYMBOL is encountered in an input
 701 file, and the symbol SYMBOL is referenced by some object file, the contents of
 702 the section are displayed as an error message.  The section is not copied into
 703 the output file, unless doing a relocatable or shared link.  This is used by
 704 glibc.
 705
 706 * New options -split-by-reloc and -split-by-file.
 707
 708 * The linker now supports linking PIC compiled code on SPARC SunOS.  It can
 709 also create SPARC SunOS shared libraries, and, like the native SunOS linker,
 710 will do so whenever there is an undefined symbol in the link and neither the -e
 711 nor the -r option was used.
 712
 713 * The -rpath option may be used on SunOS to set the list of directories to be
 714 searched at run time.  This overrides the default of building the list from the
 715 -L options.
 716
 717 * The COFF linker now combines debugging information for structs, unions, and
 718 enums, so that even if the same type is defined in multiple input files it will
 719 only be defined once in the output file.  The --traditional-format switch will
 720 prevent this optimization.
 721
 722 Changes in version 2.5:
 723
 724 * The linker now supports linking against SunOS shared libraries.  It still can
 725 not link SunOS PIC (Position Independent Code) files, so it can not be used to
 726 generate shared libraries.
 727
 728 * The linker now supports linking against ELF shared libraries for the i386
 729 (UnixWare) and SPARC (Solaris).  It can also link ELF PIC files, and can be
 730 used to generate shared libraries.  Shared library generation is not well
 731 tested; please report any problems encountered.  The linker is now enabled for
 732 Solaris again.
 733
 734 * Eric Youngdale has contributed Linux support code, including linking against
 735 Linux a.out shared libraries.  The linker produces Linux QMAGIC binaries.
 736
 737 * The ELF backend has been converted to the new linker code.  To use the new
 738 ELF linker, each particular target requires a relocation function.  So far,
 739 this function has been written for i386 (UnixWare), SPARC (Solaris) MIPS (Irix
 740 5), and HPPA ELF targets.
 741
 742 * The -( (--start-group) and -) (--end-group) options have been added to
 743 support searching a group of archives as though they were a single archive.
 744 This can also be used in a linker script, as GROUP ( files ).
 745
 746 * When a file is named on the command line, and the linker does not recognize
 747 it as an object file, the linker will now treat the file as a linker script
 748 file.  A linker script named in this way augments, but does not replace, the
 749 default linker script.
 750
 751 * The -warn-once option was added.  It causes the linker to only warn once per
 752 undefined symbol, rather than once per reference.
 753
 754 * The COFF backend has been converted to the new linker code.  As with ELF, to
 755 use the new linker, each particular target requires a relocation function.  So
 756 far, this function has been written for the i386, m68k, a29k and SH targets.
 757
 758 * The -V flag was made a synonym for -v, for SVR4 compatibility.  The old -V
 759 behaviour is available via --verbose.
 760
 761 Changes in version 2.4:
 762
 763 * New linker code, by Steve Chamberlain and Ian Taylor.  For a.out and ecoff
 764   formats (so far), this should result in considerable savings in time
 765   and memory used while linking; slightly poorer performance than
 766   before for formats not converted yet.
 767
 768 * Command-line parsing is no longer done with flex.  This means
 769   oddball characters in filenames won't get treated as argument
 770   separators.
 771
 772 * HP-PA ELF support, by Jeff Law.  (No SOM support yet.)
 773
 774 * Mach i386 support, by David Mackenzie.
 775
 776 * Irix 4 shared libraries are now supported (Irix 5 uses ELF, and ELF shared
 777   libraries are not yet supported).
 778
 779 * COFF shared libraries (as on SCO) should work as well.
 780
 781 * The linker is disabled for Solaris.  (Actually, it was in 2.3 also, I just
 782   forgot to note it.)  Some of their C library routines don't work when
 783   statically linked, and the GNU linker doesn't support dynamic linking yet.
 784
 785 Changes in version 2.3:
 786
 787 * Weak symbols are now supported.
 788
 789 * ELF support has been added.  The linker has been bootstrapped on
 790   UnixWare and Solaris.
 791
 792 * Alpha OSF/1 support has been added (non dynamic linking only).
 793
 794 Changes in version 2.2:
 795
 796 * The `bfd' library has been updated to reduce a.out-format string
 797   table size.  The effect of this is that files linked from many input
 798   files with duplicate symbols (`-g' debugging records, or identical
 799   static symbols) should be much smaller.
 800
 801 Changes in version 2.1:
 802
 803 * The ld -ySYMBOL flag (to trace references to SYMBOL) is now implemented.
 804
 805 * There is now support for writing ECOFF files, so ld and the
 806   other utilities should work on Risc/Ultrix and Irix.
 807
 808 \f
 809 Copyright (C) 2012-2020 Free Software Foundation, Inc.
 810
 811 Copying and distribution of this file, with or without modification,
 812 are permitted in any medium without royalty provided the copyright
 813 notice and this notice are preserved.
 814
 815 Local variables:
 816 fill-column: 79
 817 End: