ld/NEWS

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