ld/NEWS

   1 -*- text -*-
   2
   3 * Add -z x86-64-v[234] to the x86 ELF linker to mark x86-64-v[234] ISA
   4   level as needed.
   5
   6 * Add -z unique-symbol to avoid duplicated local symbol names.
   7
   8 * The creation of PE format DLLs now defaults to using a more secure set of DLL
   9   characteristics.
  10
  11 * The linker now deduplicates the types in .ctf sections.  The new
  12   command-line option --ctf-share-types describes how to do this:
  13   its default value, share-unconflicted, produces the most compact
  14   output.
  15
  16 * The linker now omits the "variable section" from .ctf sections by
  17   default, saving space.  This is almost certainly what you want
  18   unless you are working on a project that has its own analogue
  19   of symbol tables that are not reflected in the ELF symtabs.
  20
  21 Changes in 2.35:
  22
  23 * X86 NaCl target support is removed.
  24
  25 * Add ELF linker command-line options, --export-dynamic-symbol and
  26   --export-dynamic-symbol-list, to make symbols dynamic.
  27
  28 * Add a configure option, --enable-textrel-check=[no|yes|warning|error],
  29   to decide what ELF linker should do by default with DT_TEXTREL in an
  30   executable or shared library.  Default to yes for Linux/x86 targets.
  31
  32 * The -Map=<filename> command line option has been extended so that if
  33   <filename> is a directory then <filename>/<output-filename>.map will be
  34   created.
  35
  36 * Add a command-line option for ELF linker, --warn-textrel, to warn that
  37   DT_TEXTREL is set in a position-independent executable or shared object.
  38
  39 * Add command-line options --enable-non-contiguous-regions and
  40   --enable-non-contiguous-regions-warnings.
  41
  42 * Add command-line option --imagic for the pdp11-aout target to output format
  43   IMAGIC (0411) for separate instruction and data spaces, and change the
  44   default format option for pdp11-aout to be --omagic.
  45
  46 * Relative pathnames in INPUT() and GROUP() directives in linker scripts are
  47   searched relative to the directory of the linker script before other search
  48   paths.
  49
  50 * Add ELF linker command-line option `-z start-stop-visibility=...' to control
  51   the visibility of synthetic `__start_SECNAME` and `__stop_SECNAME` symbols.
  52
  53 * Add command-line option --dependency-file to write a Make-style dependency
  54   file listing the input files consulted by the linker, like the files written
  55   by the compiler's -M -MP options.
  56
  57 Changes in 2.34:
  58
  59 * The ld check for "PHDR segment not covered by LOAD segment" is more
  60   effective, catching cases that were wrongly allowed by previous versions of
  61   ld.  If you see this error it is likely you are linking with a bad linker
  62   script or the binary you are building is not intended to be loaded by a
  63   dynamic loader.  In the latter case --no-dynamic-linker is appropriate.
  64
  65 * cr16c support removed.
  66
  67 * Add support for z80-elf.
  68
  69 * Add support for relocation of each byte or word of multibyte value to Z80
  70   targets.
  71
  72 * Add support for Zilog eZ80 (both ADL and Z80 mode) and Zilog Z180 CPUs.
  73
  74 Changes in 2.33:
  75
  76 * Add command-line option --no-print-map-discarded.
  77
  78 * The Cortex-A53 Erratum 843419 workaround now supports a choice of which
  79   workaround to use.  The option --fix-cortex-a53-843419 now takes an
  80   optional argument --fix-cortex-a53-843419[=full|adr|adrp] which can be
  81   used to force a particular workaround to be used.  See --help for AArch64
  82   for more details.
  83
  84 * Add target handlers for AArch64 for ELF GNU program properties.
  85
  86 * Add support for GNU_PROPERTY_AARCH64_FEATURE_1_BTI in ELF GNU program
  87   properties in the AArch64 ELF linker.
  88
  89 * Add support for GNU_PROPERTY_AARCH64_FEATURE_1_PAC in ELF GNU program
  90   properties in the AArch64 ELF linker.
  91
  92 * Add -z force-bti for AArch64 to enable GNU_PROPERTY_AARCH64_FEATURE_1_BTI
  93   on output while warning about missing GNU_PROPERTY_AARCH64_FEATURE_1_BTI
  94   on inputs and use PLTs protected with BTI.
  95
  96 * Add -z pac-plt for AArch64 to pick PAC enabled PLTs.
  97
  98 Changes in 2.32:
  99
 100 * Report property change in linker map file when merging GNU properties.
 101
 102 * Add support for the C-SKY processor series.
 103
 104 * -t now doesn't report members within archives, unless -t is given twice.
 105   A single -t is now more useful when generating a list of files that should be
 106   packaged for a linker bug report.  For example:
 107     gcc hello.c -save-temps -Wl,-t | xargs realpath | sort | uniq > files
 108     tar cJf test.tar.xz `cat files`
 109
 110 Changes in 2.31:
 111
 112 * Speed up direct linking with DLLs for Cygwin and Mingw targets.
 113
 114 * Add a configure option --enable-separate-code to decide whether
 115   -z separate-code should be enabled in ELF linker by default.  Default
 116   to yes for Linux/x86 targets.  Note that -z separate-code can increase
 117   disk and memory size.
 118
 119 Changes in 2.30:
 120
 121 * Add -z separate-code to generate separate code PT_LOAD segment.
 122
 123 * Add "-z undefs" command-line option as the inverse of the "-z defs" option.
 124
 125 * Add -z globalaudit command-line option to force audit libraries to be run
 126   for every dynamic object loaded by an executable - provided that the loader
 127   supports this functionality.
 128
 129 * Tighten linker script grammar around file name specifiers to prevent the use
 130   of SORT_BY_ALIGNMENT and SORT_BY_INIT_PRIORITY on filenames.  These would
 131   previously be accepted but had no effect.
 132
 133 * The EXCLUDE_FILE directive can now be placed within any SORT_* directive
 134   within input section lists.
 135
 136 Changes in 2.29:
 137
 138 * Support for -z shstk in the x86 ELF linker to generate
 139   GNU_PROPERTY_X86_FEATURE_1_SHSTK in ELF GNU program properties.
 140
 141 * Add support for GNU_PROPERTY_X86_FEATURE_1_SHSTK in ELF GNU program
 142   properties in the x86 ELF linker.
 143
 144 * Add support for GNU_PROPERTY_X86_FEATURE_1_IBT in ELF GNU program
 145   properties in the x86 ELF linker.
 146
 147 * Support for -z ibtplt in the x86 ELF linker to generate IBT-enabled
 148   PLT.
 149
 150 * Support for -z ibt in the x86 ELF linker to generate IBT-enabled
 151   PLT as well as GNU_PROPERTY_X86_FEATURE_1_IBT in ELF GNU program
 152   properties.
 153
 154 * Add support for ELF SHF_GNU_MBIND and PT_GNU_MBIND_XXX.
 155
 156 * Add support for ELF GNU program properties.
 157
 158 * Add support for the Texas Instruments PRU processor.
 159
 160 * When configuring for arc*-*-linux* targets the default linker emulation will
 161   change if --with-cpu=nps400 is used at configure time.
 162
 163 * Improve assignment of LMAs to orphan sections in some edge cases where a
 164   mixture of both AT>LMA_REGION and AT(LMA) are used.
 165
 166 * Orphan sections placed after an empty section that has an AT(LMA) will now
 167   take an load memory address starting from LMA.
 168
 169 * Section groups can now be resolved (the group deleted and the group members
 170   placed like normal sections) at partial link time either using the new linker
 171   option --force-group-allocation or by placing FORCE_GROUP_ALLOCATION into the
 172   linker script.
 173
 174 Changes in 2.28:
 175
 176 * The EXCLUDE_FILE linker script construct can now be applied outside of the
 177   section list in order for the exclusions to apply over all input sections in
 178   the list.
 179
 180 * Add support for the RISC-V architecture.
 181
 182 * The command-line option --no-eh-frame-hdr can now be used in ELF based
 183   linkers to disable the automatic generation of .eh_frame_hdr sections.
 184
 185 * Add --in-implib=<infile> to the ARM linker to enable specifying a set of
 186   Secure Gateway veneers that must exist in the output import library specified
 187   by --out-implib=<outfile> and the address they must have.  As such,
 188   --in-implib is only supported in combination with --cmse-implib.
 189
 190 * Extended the --out-implib=<file> option, previously restricted to x86 PE
 191   targets, to any ELF based target.  This allows the generation of an import
 192   library for an ELF executable, which can then be used by another application
 193   to link against the executable.
 194
 195 Changes in 2.27:
 196
 197 * Add a configure option --enable-relro to decide whether -z relro should
 198   be enabled in ELF linker by default.  Default to yes for all Linux
 199   targets except FRV, HPPA, IA64 and MIPS.  Note that -z relro can increase
 200   disk and memory size.
 201
 202 * Support for -z noreloc-overflow in the x86-64 ELF linker to disable
 203   relocation overflow check.
 204
 205 * Add -z common/-z nocommon options for ELF targets to control whether to
 206   convert common symbols to the STT_COMMON type during a relocatable link.
 207
 208 * Support for -z nodynamic-undefined-weak in the x86 ELF linker, which
 209   avoids dynamic relocations against undefined weak symbols in executable.
 210
 211 * The NOCROSSREFSTO command was added to the linker script language.
 212
 213 * Add --no-apply-dynamic-relocs to the AArch64 linker to do not apply link-time
 214   values for dynamic relocations.
 215
 216 Changes in 2.26:
 217
 218 * Add --fix-stm32l4xx-629360 to the ARM linker to enable a link-time
 219   workaround for a bug in the bus matrix / memory controller for some of
 220   the STM32 Cortex-M4 based products (STM32L4xx)
 221
 222 * Add a configure option --enable-compressed-debug-sections={all,ld} to
 223   decide whether DWARF debug sections should be compressed by default.
 224
 225 * Add support for the ARC EM/HS, and ARC600/700 architectures.
 226
 227 * Experimental support for linker garbage collection (--gc-sections)
 228   has been enabled for COFF and PE based targets.
 229
 230 * New command-line option for ELF targets to compress DWARF debug
 231   sections, --compress-debug-sections=[none|zlib|zlib-gnu|zlib-gabi].
 232
 233 * New command-line option, --orphan-handling=[place|warn|error|discard], to
 234   adjust how orphan sections are handled.  The default is 'place' which gives
 235   the current behaviour, 'warn' and 'error' issue a warning or error
 236   respectively when orphan sections are found, and 'discard' will discard all
 237   orphan sections.
 238
 239 * Add support for LLVM plugin.
 240
 241 * Add --print-memory-usage option to report memory blocks usage.
 242
 243 * Add --require-defined option, it's like --undefined except the new symbol
 244   must be defined by the end of the link.
 245
 246 Changes in 2.25:
 247
 248 * PE binaries now once again contain real timestamps by default.  To disable
 249   the inclusion of a timestamp in a PE binary, use the --no-insert-timestamp
 250   command-line option.
 251
 252 * Replace support for openrisc and or32 with support for or1k.
 253
 254 * Add support for the --build-id command-line option to COFF based targets.
 255
 256 * x86/x86_64 pe-coff now supports the --build-id option.
 257
 258 * Add support for the Andes NDS32.
 259
 260 Changes in 2.24:
 261
 262 * Add LOG2CEIL() builtin function to the linker script language
 263
 264 * Add support for the Texas Instruments MSP430X processor.
 265
 266 * Add support for Altera Nios II.
 267
 268 * Add support for the V850E3V5 architecture.
 269
 270 * Add support for the Imagination Technologies Meta processor.
 271
 272 * --enable-new-dtags no longer generates old dtags in addition to new dtags.
 273
 274 * Remove linker support for MIPS ECOFF targets.
 275
 276 * Add ALIGN_WITH_INPUT to the linker script language to force the alignment of
 277   an output section to use the maximum alignment of all its input sections.
 278
 279 Changes in 2.23:
 280
 281 * Enable compressed debug section feature for x86/x86_64 pe-coff.
 282
 283 * Add support for the 64-bit ARM architecture: AArch64.
 284
 285 * Added SORT_NONE to the linker script language to disable section sorting.
 286
 287 * Add a linker-provided symbol when producing ELF output, '__ehdr_start'
 288   to point to the ELF file header (and nearby program headers) in the
 289   program's memory image.
 290
 291 * Add support for S12X processor.
 292
 293 * Add support for the VLE extension to the PowerPC architecture.
 294
 295 * Add support for the Freescale XGATE architecture.
 296
 297 * Add option -f FILE on AIX (for response file).
 298
 299 * Add support for the Renesas RL78 architecture.
 300
 301 * Add support for the Adapteva EPIPHANY architecture.
 302
 303 Changes in 2.22:
 304
 305 * --copy-dt-needed-entries is no longer enabled by default.  Instead
 306   --no-copy-dt-needed-entries is the default.
 307
 308 * INPUT_SECTION_FLAGS has been added to the linker script language
 309   to allow selection of input sections by section header section flags.
 310
 311 * Add support for the Tilera TILEPro and TILE-Gx architectures.
 312
 313 * Added SORT_BY_INIT_PRIORITY to the linker script language to permit
 314   sorting sections by numerical value of the GCC init_priority attribute
 315   encoded in the section name.
 316
 317 Changes in 2.21:
 318
 319 * Linker script expression evaluation is somewhat more sane.  This may
 320   break scripts that depend on quirks of the old expression evaluation.
 321
 322 * Turn off underscoring for x86_64 PE+-COFF targets.  For old behavior the
 323   option --enable-leading-mingw64-underscores can be used on configure of
 324   bfd.
 325
 326 * Add support for the TMS320C6000 (TI C6X) processor family.
 327
 328 * --add-needed renamed to --copy-dt-needed-entries in order to avoid confusion
 329   with --as-needed option.
 330
 331 * Extend .def file syntax by '== <ID>' for imports and exports. This allows
 332   to alias the import/export table name written in PE image.
 333
 334 * Add --exclude-all-symbols option to PE based linkers.  This prevents all
 335   symbols from automatically being exported.
 336
 337 * Add support for the Renesas RX processor.
 338
 339 * Add support for alpha-vms target.
 340
 341 Changes in 2.20:
 342
 343 * GNU/Linux targets now support the STB_GNU_UNIQUE symbol binding.  This is a
 344   GNU extension to the standard set of ELF symbol bindings.  The binding will
 345   be passed on to the dynamic linker which will make sure that in the entire
 346   process there is just one symbol with the given name and type in use.
 347
 348 * PE targets now support a GNU extension to allow the alignment of common
 349   common symbols to be specified.  This support uses custom options in
 350   the .drectve section, which will be disregarded by the native tools.
 351
 352 * PE targets now add primitive support for ELF version scripts; symbols
 353   are not versioned, but the local and global symbol visibility directives
 354   are respected when filtering symbols in auto-export mode.
 355
 356 * New option --no-export-dynamic to undo the effect of the -E and
 357   --export-dynamic options.
 358
 359 * ELF: --warn-alternate-em option to warn if an object has alternate
 360   ELF machine code.
 361
 362 * New script function REGION_ALIAS to add alias names to memory regions.
 363
 364 * PE targets no longer make use of the long section names PE extension to
 365   the COFF format when generating executable images, by default.  The old
 366   (slightly non-conformant) behaviour can still be invoked by using the
 367   new '--enable-long-section-names' command-line option.  It is also enabled
 368   automatically in the presence of un-stripped debug information, as GDB
 369   needs to be able to find the debug info sections by their full names.
 370
 371 * For GNU/Linux systems the linker will now avoid processing any relocations
 372   made against symbols of the STT_GNU_IFUNC type and instead emit them into
 373   the resulting binary for processing by the loader.
 374
 375 * --as-needed now links in a dynamic library if it satisfies undefined
 376   symbols in regular objects, or in other dynamic libraries.  In the
 377   latter case the library is not linked if it is found in a DT_NEEDED
 378   entry of one of the libraries already linked.
 379
 380 * Add a new command-line option, -Ttext-segment ADDR, for ELF targets
 381   to set the address of the first byte of the text segment.
 382
 383 * Add support for Sunplus score architecture.
 384
 385 * Add new option --use-nul-prefixed-import-tables to ld for PE targets to
 386   allow fallback to old import table generation with null element prefix.
 387
 388 * Windows PE systems now support a new --exclude-modules-for-implib option,
 389   allowing users to partition object files and archive members between a DLL
 390   and its associated import library as they are generated during linking.
 391
 392 * Add support for Lattice Mico32 (lm32) architecture.
 393
 394 * Add CR16 ELF --embedded-relocs (used to embedded relocations into binaries
 395   for Embedded-PIC code) option.
 396
 397 * Add to the PE/PE+ targets the support of two different kinds of
 398   pseudo-relocations.  They can be selected by the switches
 399   --enable-runtime-pseudo-reloc-v1 and --enable-runtime-pseudo-reloc-v2.
 400   For the switch --enable-runtime-pseudo-reloc it uses for 32-bit
 401   runtime pseudo relocation version one, for 64-bit the version two.
 402
 403 Changes in 2.19:
 404
 405 * Linker scripts support a new INSERT command that makes it easier to
 406   augment the default script.
 407
 408 * Linker script input section filespecs may now specify a file within an
 409   archive by writing "archive:file".
 410
 411 * The --sort-common switch now has an optional argument which specifies the
 412   direction of sorting.
 413
 414 * The M68K linker now supports multiple GOT generation schemes controlled via
 415   the --got=<type> command-line option.
 416
 417 * The ARM EABI linker will now generate stubs for function calls to symbols
 418   that are too far away.  The placement of the stubs is controlled by a new
 419   linker command-line option: --stub-group-size=N.
 420
 421 Changes in 2.18:
 422
 423 * Linker sources now released under version 3 of the GNU General Public
 424   License.
 425
 426 * ELF: New --build-id option to generate a unique per-binary identifier
 427   embedded in a note section.
 428
 429 * Added support for National Semicondutor CompactRISC (ie CR16) target.
 430
 431 * -l:foo now searches the library path for a filename called foo,
 432   without converting it to libfoo.a or libfoo.so.
 433
 434 * Add a new command-line option '--default-script=FILE' or '-dT FILE'
 435   which specifies a replacement for the built in, default linker
 436   script.
 437
 438 * ELF: Add -Bsymbolic-functions, --dynamic-list-cpp-new, which puts C++
 439   operator new and delete on the dynamic list, and --dynamic-list-data,
 440   builtin list for --dynamic-list, which puts global data symbols on the
 441   dynamic list.
 442
 443 * Add support for x86_64 PE+ target.
 444
 445 * Add support for Score target.
 446
 447 * ELF: Add --dynamic-list option to specify a list of global symbols
 448   whose references shouldn't be bound to the definition within the
 449   shared library, or a list of symbols which should be added to the
 450   symbol table in the executable.
 451
 452 * The default output section LMA has changed for allocatable sections from
 453   being equal to VMA, to keeping the difference between LMA and VMA the same as
 454   the previous output section in the same region.  This is a more useful
 455   default when using overlays and other cases where you specify an LMA
 456   differing from the VMA for some sections.
 457
 458 * New switch: --print-gc-sections to list any sections removed by garabge
 459   collection.
 460
 461 * ARM: Added --vfp11-denorm-fix option to work around an erratum in current
 462   VFP11 coprocessors.
 463
 464 Changes in 2.17:
 465
 466 * Support for the Infineon XC16X has been added by KPIT Cummins Infosystems.
 467
 468 * Modify the Linux linker search order to better match ld.so search order.
 469   Look for DT_NEEDED libraries in paths specified by ld.so.conf before
 470   searching the default directories, rather than vice versa.
 471   Use $prefix/etc/ld.so.conf if it exists, otherwise /etc/ld.so.conf.
 472
 473 * PE-COFF: Forward exports from DLL's can now be specified in .def files
 474   passed directly to ld.
 475
 476 * Support for the Z80 processor family has been added.
 477
 478 * Add support for the "@<file>" syntax to the command line, so that extra
 479   switches can be read from <file>.
 480
 481 Changes in 2.16:
 482
 483 * Support for the R_ARM_V4BX relocation as defined in the ARM AAELF
 484   specification has been added via the --fix-v4bx command-line option.
 485
 486 * New linker script construct AS_NEEDED(), which sets the --as-needed flag
 487   for input files listed inside of it.
 488
 489 * A new command-line option, --sysroot, can be used to override the
 490   default sysroot location.  It only applies to toolchains that were
 491   configured using --with-sysroot.
 492
 493 * New linker script functions: ORIGIN() and LENGTH() which return information
 494   about a specified memory region.
 495
 496 * Port to MAXQ processor contributed by HCL Tech.
 497
 498 * Added SEGMENT_START to the linker script language to permit the user to
 499   override the base address for a segment from the command-line.
 500
 501 * ELF: --warn-shared-textrel option to warn if adding a DT_TEXTREL to a shared
 502   object.
 503
 504 * Added SORT_BY_NAME and SORT_BY_ALIGNMENT to the linker script
 505   language to permit sorting sections by section name or section
 506   maximum alignment.
 507
 508 * Added a new linker command-line switch, --sort-section name|alignment,
 509   to sort sections by section name or maximum alignment.
 510
 511 * ELF: --add-needed/--no-add-needed options to control if a DT_NEEDED tag
 512   should be added when a shared library comes from DT_NEEDED tags.
 513
 514 * Support for the crx-elf target added.
 515
 516 * Support for the sh-symbianelf target added.
 517
 518 * A new linker command-line switch has been added which allows the hash table
 519   size to be set to a suitable prime value near to its argument.  This switch
 520   is --hash-size=<NUMBER>.  Also if the switch --reduce-memory-overheads is
 521   used, and --hash-size has not been used, then the default value will be set
 522   to 1021.
 523
 524 * Linker map files are now generated with an O(N) algorithm for finding symbols
 525   that are defined in each section.  This uses about 40% more memory for
 526   symbols than the old O(N^2) algorithm.  You can use the new
 527   --reduce-memory-overheads option to select the old algorithm; this option
 528   might also be used in the future to select similar tradeoffs.
 529
 530 Changes in 2.15:
 531
 532 * ELF: --as-needed/--no-as-needed options to control if a DT_NEEDED tag should
 533   be added only when a shared library is referenced.
 534
 535 * PE: --large-address-aware option to indicate executables support virtual
 536   addresses greater than 2 gigabytes.
 537
 538 * DWARF 2 support for i386pe added.
 539
 540 * The linker script operator DEFINED() will now yield 1 only for a symbol that
 541   is defined before the statement where DEFINED is used.
 542
 543 * The MIPS --embedded-relocs (used to embed relocations into binaries for
 544   Embedded-PIC code) is deprecated and will be removed in a future release.
 545
 546 * cr16c support added by NSC.
 547
 548 * m32r Linux (ELF) support added by Renesas.
 549
 550 * Improved linker's handling of unresolved symbols.  The switch
 551   --unresolved-symbols=<method> has been added to tell the linker when it
 552   should report them and the switch --warn-unresolved-symbols has been added to
 553   make reports be issued as warning messages rather than errors.
 554
 555 Changes in 2.14:
 556
 557 * Added support for Xtensa architecture.
 558
 559 * Added --with-sysroot configure switch to specify a target system root, for
 560   linking against a target filesystem image.
 561
 562 * Added --accept-unknown-linker-format to restore old linker behaviour (pre
 563   2.14) of silently accepting and linking in any files in an unknown binary
 564   file format.
 565
 566 * Added --no-omagic to undo the effects of the -N option.
 567
 568 * Support for Texas Instruments TMS320C4x and TMS320C3x series of
 569   DSP's contributed by Michael Hayes and Svein E. Seldal.
 570
 571 * Added --with-lib-path configure switch to specify default value for
 572   LIB_PATH.
 573
 574 * ARM port to QNX operating system added by Graeme Peterson.
 575
 576 * IP2K support added by Denis Chertykov.
 577
 578 Changes in 2.13:
 579
 580 * Support for the Fujitsu FRV architecture added by Red Hat. Models for FR400
 581   and FR500 included.
 582
 583 Changes in version 2.13:
 584
 585 * DEC VAX ELF support, by Matt Thomas.
 586
 587 Changes in version 2.12:
 588
 589 * Support for Don Knuth's MMIX, by Hans-Peter Nilsson.
 590
 591 * Support for the OpenRISC 32-bit embedded processor by OpenCores.
 592
 593 * Support for -z nocopyreloc in the x86 ELF linker, which disables
 594   production of copy relocs.  Warning: using this option may result in
 595   non-sharable applications.
 596
 597 * Support for -z combreloc in the ELF linker, which puts dynamic
 598   relocations against the same symbol together, so that dynamic linker
 599   can use an one-entry symbol lookup cache.
 600
 601 * Support for ELF SHF_MERGE section merging, by Jakub Jelinek.
 602
 603 Changes in version 2.11:
 604
 605 * Support for AMD x86-64 architecture, by Jan Hubicka, SuSE Labs.
 606
 607 * Support added for eliminating duplicate DWARF2 debug information by
 608   having the compiler generate the information in sections called
 609   .gnu.linkonce.wi.XXXX where XXXX is a checksum for the contents.  The
 610   linker then merges these sections together into the normal .debug_info
 611   section.
 612
 613 * The native ELF linker now searches the directories in DT_RUNPATH or
 614   DT_RPATH of a shared library for shared libraries needed by it.
 615
 616 * TI C54x support, by Timothy Wall.
 617
 618 * Added command-line switch --section-start to set the start address of any
 619   specified section.
 620
 621 * Added ability to emit full relocation information in linked executables,
 622   enabled by --emit-relocs.  Some post-linkage optimization tools need
 623   this information in order to be able to correctly identify and perform
 624   symbol relative addressing in the event of changes in section contents
 625   (instructions being added or deleted, extending data sections, etc.)
 626
 627 * Support for i860, by Jason Eckhardt (preliminary, alpha quality).
 628
 629 * Support for CRIS (Axis Communications ETRAX series).
 630
 631 * Support for PDP-11 and 2.11BSD a.out format, by Lars Brinkhoff.
 632
 633 Changes in version 2.10:
 634
 635 * Added AT> to the linker script language to allow load-time allocation of
 636   sections into regions.
 637
 638 * Added garbage collection of unused sections, enabled by --gc-sections.
 639   It does require a bit of backend support; currently implemented are
 640   arm-elf, avr-elf, d10v-elf, fr30-elf, i386-elf, m32r-elf, m68k-elf,
 641   mcore-elf, mips-elf, mn10300-elf, ppc-elf, sh-elf, sparc-elf, and v850-elf.
 642   Others will ignore the option.
 643
 644 * Added SORT to the linker script language to permit sorting sections by file
 645   name or section name.
 646
 647 * Added EXTERN to the linker script language as an equivalent to the -u
 648   command-line option.
 649
 650 * Added ASSERT to the linker script language.
 651
 652 * Added EXCLUDE_FILE to the linker script language for further control over
 653   wildcard file names.
 654
 655 * Added -O option to optimize linker output (as of this writing, this only
 656   affects ELF shared library generation).
 657
 658 * The -e option now accepts a number as well as a symbol name.
 659
 660 * Added --no-undefined option to disallow undefined symbols when creating a
 661   shared library.
 662
 663 * The linker now issues a warning, not an error, for an undefined symbol when
 664   using -Bsymbolic; use the new --no-undefined option to get the old
 665   behaviour.
 666
 667 * Added --demangle and --no-demangle options.
 668
 669 Changes in version 2.9:
 670
 671 * Added SQUAD to the linker script language.
 672
 673 * New option --no-warn-mismatch.
 674
 675 * The MEMORY command now parses the attributes to determine where sections that
 676   are not placed in a specific memory region are placed.
 677
 678 Changes in version 2.8:
 679
 680 * Linker scripts may now contain shell wildcard characters for file and section
 681   names.
 682
 683 * The linker now supports symbol versions in ELF.
 684
 685 * The NOCROSSREFS command was added to the linker script language.
 686
 687 * The LOADADDR expression was added to the linker script language.
 688
 689 * MAX and MIN functions were added to the linker script language.
 690
 691 * The OVERLAY construct was added to the linker script language.
 692
 693 * New option --warn-section-align to warn when the address of an output section
 694   changes due to alignment of an input section.
 695
 696 * New options --filter/-F and --auxiliary/-f.
 697
 698 Changes in version 2.7:
 699
 700 * New option --cref to print out a cross reference table.
 701
 702 * New option --wrap SYMBOL.
 703
 704 * New option --no-whole-archive, to turn off the effect of --whole-archive.
 705
 706 * Input sections assigned to the output section /DISCARD/ in the linker script
 707   are not included in the output file.
 708
 709 * The SunOS and ELF linkers now merge stabs debugging information which uses
 710   the N_BINCL and N_EINCL stab types.  This reduces the amount of debugging
 711   information generated.
 712
 713 Changes in version 2.6:
 714
 715 * When an ELF section name is representable as a C identifier (this is not true
 716 of most ELF section names), the linker will automatically define symbols
 717 __start_SECNAME and __stop_SECNAME, where SECNAME is the section name, at the
 718 beginning and the end of the section.  This is used by glibc.
 719
 720   Addendum: Current versions of the linker (at least for version 2.18 onwards
 721 and possibly much earlier as well) place two restrictions on this feature:  The
 722 symbols are only implemented for orphaned sections, not for explicitly placed
 723 sections and they are PROVIDEd rather than being defined.
 724
 725 * When an ELF section named .gnu.warning is encountered in an input file, the
 726 contents of the section are displayed as an error message, and the section is
 727 not copied into the output file.  This is used by glibc.
 728
 729 * When an ELF section named .gnu.warning.SYMBOL is encountered in an input
 730 file, and the symbol SYMBOL is referenced by some object file, the contents of
 731 the section are displayed as an error message.  The section is not copied into
 732 the output file, unless doing a relocatable or shared link.  This is used by
 733 glibc.
 734
 735 * New options -split-by-reloc and -split-by-file.
 736
 737 * The linker now supports linking PIC compiled code on SPARC SunOS.  It can
 738 also create SPARC SunOS shared libraries, and, like the native SunOS linker,
 739 will do so whenever there is an undefined symbol in the link and neither the -e
 740 nor the -r option was used.
 741
 742 * The -rpath option may be used on SunOS to set the list of directories to be
 743 searched at run time.  This overrides the default of building the list from the
 744 -L options.
 745
 746 * The COFF linker now combines debugging information for structs, unions, and
 747 enums, so that even if the same type is defined in multiple input files it will
 748 only be defined once in the output file.  The --traditional-format switch will
 749 prevent this optimization.
 750
 751 Changes in version 2.5:
 752
 753 * The linker now supports linking against SunOS shared libraries.  It still can
 754 not link SunOS PIC (Position Independent Code) files, so it can not be used to
 755 generate shared libraries.
 756
 757 * The linker now supports linking against ELF shared libraries for the i386
 758 (UnixWare) and SPARC (Solaris).  It can also link ELF PIC files, and can be
 759 used to generate shared libraries.  Shared library generation is not well
 760 tested; please report any problems encountered.  The linker is now enabled for
 761 Solaris again.
 762
 763 * Eric Youngdale has contributed Linux support code, including linking against
 764 Linux a.out shared libraries.  The linker produces Linux QMAGIC binaries.
 765
 766 * The ELF backend has been converted to the new linker code.  To use the new
 767 ELF linker, each particular target requires a relocation function.  So far,
 768 this function has been written for i386 (UnixWare), SPARC (Solaris) MIPS (Irix
 769 5), and HPPA ELF targets.
 770
 771 * The -( (--start-group) and -) (--end-group) options have been added to
 772 support searching a group of archives as though they were a single archive.
 773 This can also be used in a linker script, as GROUP ( files ).
 774
 775 * When a file is named on the command line, and the linker does not recognize
 776 it as an object file, the linker will now treat the file as a linker script
 777 file.  A linker script named in this way augments, but does not replace, the
 778 default linker script.
 779
 780 * The -warn-once option was added.  It causes the linker to only warn once per
 781 undefined symbol, rather than once per reference.
 782
 783 * The COFF backend has been converted to the new linker code.  As with ELF, to
 784 use the new linker, each particular target requires a relocation function.  So
 785 far, this function has been written for the i386, m68k, a29k and SH targets.
 786
 787 * The -V flag was made a synonym for -v, for SVR4 compatibility.  The old -V
 788 behaviour is available via --verbose.
 789
 790 Changes in version 2.4:
 791
 792 * New linker code, by Steve Chamberlain and Ian Taylor.  For a.out and ecoff
 793   formats (so far), this should result in considerable savings in time
 794   and memory used while linking; slightly poorer performance than
 795   before for formats not converted yet.
 796
 797 * Command-line parsing is no longer done with flex.  This means
 798   oddball characters in filenames won't get treated as argument
 799   separators.
 800
 801 * HP-PA ELF support, by Jeff Law.  (No SOM support yet.)
 802
 803 * Mach i386 support, by David Mackenzie.
 804
 805 * Irix 4 shared libraries are now supported (Irix 5 uses ELF, and ELF shared
 806   libraries are not yet supported).
 807
 808 * COFF shared libraries (as on SCO) should work as well.
 809
 810 * The linker is disabled for Solaris.  (Actually, it was in 2.3 also, I just
 811   forgot to note it.)  Some of their C library routines don't work when
 812   statically linked, and the GNU linker doesn't support dynamic linking yet.
 813
 814 Changes in version 2.3:
 815
 816 * Weak symbols are now supported.
 817
 818 * ELF support has been added.  The linker has been bootstrapped on
 819   UnixWare and Solaris.
 820
 821 * Alpha OSF/1 support has been added (non dynamic linking only).
 822
 823 Changes in version 2.2:
 824
 825 * The `bfd' library has been updated to reduce a.out-format string
 826   table size.  The effect of this is that files linked from many input
 827   files with duplicate symbols (`-g' debugging records, or identical
 828   static symbols) should be much smaller.
 829
 830 Changes in version 2.1:
 831
 832 * The ld -ySYMBOL flag (to trace references to SYMBOL) is now implemented.
 833
 834 * There is now support for writing ECOFF files, so ld and the
 835   other utilities should work on Risc/Ultrix and Irix.
 836
 837 \f
 838 Copyright (C) 2012-2020 Free Software Foundation, Inc.
 839
 840 Copying and distribution of this file, with or without modification,
 841 are permitted in any medium without royalty provided the copyright
 842 notice and this notice are preserved.
 843
 844 Local variables:
 845 fill-column: 79
 846 End: