ld/NEWS

   1 -*- text -*-
   2
   3 * Experimental support for linker garbage collection (--gc-sections)
   4   has been enabled for COFF and PE based targets.
   5
   6 * New command line option for ELF targets to compress DWARF debug
   7   sections, --compress-debug-sections=[none|zlib|zlib-gnu|zlib-gabi].
   8
   9 * New command line option, --orphan-handling=[place|warn|error|discard], to
  10   adjust how orphan sections are handled.  The default is 'place' which gives
  11   the current behaviour, 'warn' and 'error' issue a warning or error
  12   respectively when orphan sections are found, and 'discard' will discard all
  13   orphan sections.
  14
  15 * Add support for LLVM plugin.
  16
  17 * Add --print-memory-usage option to report memory blocks usage.
  18
  19 * Add --require-defined option, it's like --undefined except the new symbol
  20   must be defined by the end of the link.
  21
  22 Changes in 2.25:
  23
  24 * PE binaries now once again contain real timestamps by default.  To disable
  25   the inclusion of a timestamp in a PE binary, use the --no-insert-timestamp
  26   command line option.
  27
  28 * Replace support for openrisc and or32 with support for or1k.
  29
  30 * Add support for the --build-id command line option to COFF based targets.
  31
  32 * x86/x86_64 pe-coff now supports the --build-id option.
  33
  34 * Add support for the Andes NDS32.
  35
  36 Changes in 2.24:
  37
  38 * Add LOG2CEIL() builtin function to the linker script language
  39
  40 * Add support for the Texas Instruments MSP430X processor.
  41
  42 * Add support for Altera Nios II.
  43
  44 * Add support for the V850E3V5 architecture.
  45
  46 * Add support for the Imagination Technologies Meta processor.
  47
  48 * --enable-new-dtags no longer generates old dtags in addition to new dtags.
  49
  50 * Remove linker support for MIPS ECOFF targets.
  51
  52 * Add ALIGN_WITH_INPUT to the linker script language to force the alignment of
  53   an output section to use the maximum alignment of all its input sections.
  54
  55 Changes in 2.23:
  56
  57 * Enable compressed debug section feature for x86/x86_64 pe-coff.
  58
  59 * Add support for the 64-bit ARM architecture: AArch64.
  60
  61 * Added SORT_NONE to the linker script language to disable section sorting.
  62
  63 * Add a linker-provided symbol when producing ELF output, '__ehdr_start'
  64   to point to the ELF file header (and nearby program headers) in the
  65   program's memory image.
  66
  67 * Add support for S12X processor.
  68
  69 * Add support for the VLE extension to the PowerPC architecture.
  70
  71 * Add support for the Freescale XGATE architecture.
  72
  73 * Add option -f FILE on AIX (for response file).
  74
  75 * Add support for the Renesas RL78 architecture.
  76
  77 * Add support for the Adapteva EPIPHANY architecture.
  78
  79 Changes in 2.22:
  80
  81 * --copy-dt-needed-entries is no longer enabled by default.  Instead
  82   --no-copy-dt-needed-entries is the default.
  83
  84 * INPUT_SECTION_FLAGS has been added to the linker script language
  85   to allow selection of input sections by section header section flags.
  86
  87 * Add support for the Tilera TILEPro and TILE-Gx architectures.
  88
  89 * Added SORT_BY_INIT_PRIORITY to the linker script language to permit
  90   sorting sections by numerical value of the GCC init_priority attribute
  91   encoded in the section name.
  92
  93 Changes in 2.21:
  94
  95 * Linker script expression evaluation is somewhat more sane.  This may
  96   break scripts that depend on quirks of the old expression evaluation.
  97
  98 * Turn off underscoring for x86_64 PE+-COFF targets.  For old behavior the
  99   option --enable-leading-mingw64-underscores can be used on configure of
 100   bfd.
 101
 102 * Add support for the TMS320C6000 (TI C6X) processor family.
 103
 104 * --add-needed renamed to --copy-dt-needed-entries in order to avoid confusion
 105   with --as-needed option.
 106
 107 * Extend .def file syntax by '== <ID>' for imports and exports. This allows
 108   to alias the import/export table name written in PE image.
 109
 110 * Add --exclude-all-symbols option to PE based linkers.  This prevents all
 111   symbols from automatically being exported.
 112
 113 * Add support for the Renesas RX processor.
 114
 115 * Add support for alpha-vms target.
 116
 117 Changes in 2.20:
 118
 119 * GNU/Linux targets now support the STB_GNU_UNIQUE symbol binding.  This is a
 120   GNU extension to the standard set of ELF symbol bindings.  The binding will
 121   be passed on to the dynamic linker which will make sure that in the entire
 122   process there is just one symbol with the given name and type in use.
 123
 124 * PE targets now support a GNU extension to allow the alignment of common
 125   common symbols to be specified.  This support uses custom options in
 126   the .drectve section, which will be disregarded by the native tools.
 127
 128 * PE targets now add primitive support for ELF version scripts; symbols
 129   are not versioned, but the local and global symbol visibility directives
 130   are respected when filtering symbols in auto-export mode.
 131
 132 * New option --no-export-dynamic to undo the effect of the -E and
 133   --export-dynamic options.
 134
 135 * ELF: --warn-alternate-em option to warn if an object has alternate
 136   ELF machine code.
 137
 138 * New script function REGION_ALIAS to add alias names to memory regions.
 139
 140 * PE targets no longer make use of the long section names PE extension to
 141   the COFF format when generating executable images, by default.  The old
 142   (slightly non-conformant) behaviour can still be invoked by using the
 143   new '--enable-long-section-names' command-line option.  It is also enabled
 144   automatically in the presence of un-stripped debug information, as GDB
 145   needs to be able to find the debug info sections by their full names.
 146
 147 * For GNU/Linux systems the linker will now avoid processing any relocations
 148   made against symbols of the STT_GNU_IFUNC type and instead emit them into
 149   the resulting binary for processing by the loader.
 150
 151 * --as-needed now links in a dynamic library if it satisfies undefined
 152   symbols in regular objects, or in other dynamic libraries.  In the
 153   latter case the library is not linked if it is found in a DT_NEEDED
 154   entry of one of the libraries already linked.
 155
 156 * Add a new command line option, -Ttext-segment ADDR, for ELF targets
 157   to set the address of the first byte of the text segment.
 158
 159 * Add support for Sunplus score architecture.
 160
 161 * Add new option --use-nul-prefixed-import-tables to ld for PE targets to
 162   allow fallback to old import table generation with null element prefix.
 163
 164 * Windows PE systems now support a new --exclude-modules-for-implib option,
 165   allowing users to partition object files and archive members between a DLL
 166   and its associated import library as they are generated during linking.
 167
 168 * Add support for Lattice Mico32 (lm32) architecture.
 169
 170 * Add CR16 ELF --embedded-relocs (used to embedded relocations into binaries
 171   for Embedded-PIC code) option.
 172
 173 * Add to the PE/PE+ targets the support of two different kinds of
 174   pseudo-relocations.  They can be selected by the switches
 175   --enable-runtime-pseudo-reloc-v1 and --enable-runtime-pseudo-reloc-v2.
 176   For the switch --enable-runtime-pseudo-reloc it uses for 32-bit
 177   runtime pseudo relocation version one, for 64-bit the version two.
 178
 179 Changes in 2.19:
 180
 181 * Linker scripts support a new INSERT command that makes it easier to
 182   augment the default script.
 183
 184 * Linker script input section filespecs may now specify a file within an
 185   archive by writing "archive:file".
 186
 187 * The --sort-common switch now has an optional argument which specifies the
 188   direction of sorting.
 189
 190 * The M68K linker now supports multiple GOT generation schemes controlled via
 191   the --got=<type> command line option.
 192
 193 * The ARM EABI linker will now generate stubs for function calls to symbols
 194   that are too far away.  The placement of the stubs is controlled by a new
 195   linker command line option: --stub-group-size=N.
 196
 197 Changes in 2.18:
 198
 199 * Linker sources now released under version 3 of the GNU General Public
 200   License.
 201
 202 * ELF: New --build-id option to generate a unique per-binary identifier
 203   embedded in a note section.
 204
 205 * Added support for National Semicondutor CompactRISC (ie CR16) target.
 206
 207 * -l:foo now searches the library path for a filename called foo,
 208   without converting it to libfoo.a or libfoo.so.
 209
 210 * Add a new command line option '--default-script=FILE' or '-dT FILE'
 211   which specifies a replacement for the built in, default linker
 212   script.
 213
 214 * ELF: Add -Bsymbolic-functions, --dynamic-list-cpp-new, which puts C++
 215   operator new and delete on the dynamic list, and --dynamic-list-data,
 216   builtin list for --dynamic-list, which puts global data symbols on the
 217   dynamic list.
 218
 219 * Add support for x86_64 PE+ target.
 220
 221 * Add support for Score target.
 222
 223 * ELF: Add --dynamic-list option to specify a list of global symbols
 224   whose references shouldn't be bound to the definition within the
 225   shared library, or a list of symbols which should be added to the
 226   symbol table in the executable.
 227
 228 * The default output section LMA has changed for allocatable sections from
 229   being equal to VMA, to keeping the difference between LMA and VMA the same as
 230   the previous output section in the same region.  This is a more useful
 231   default when using overlays and other cases where you specify an LMA
 232   differing from the VMA for some sections.
 233
 234 * New switch: --print-gc-sections to list any sections removed by garabge
 235   collection.
 236
 237 * ARM: Added --vfp11-denorm-fix option to work around an erratum in current
 238   VFP11 coprocessors.
 239
 240 Changes in 2.17:
 241
 242 * Support for the Infineon XC16X has been added by KPIT Cummins Infosystems.
 243
 244 * Modify the Linux linker search order to better match ld.so search order.
 245   Look for DT_NEEDED libraries in paths specified by ld.so.conf before
 246   searching the default directories, rather than vice versa.
 247   Use $prefix/etc/ld.so.conf if it exists, otherwise /etc/ld.so.conf.
 248
 249 * PE-COFF: Forward exports from DLL's can now be specified in .def files
 250   passed directly to ld.
 251
 252 * Support for the Z80 processor family has been added.
 253
 254 * Add support for the "@<file>" syntax to the command line, so that extra
 255   switches can be read from <file>.
 256
 257 Changes in 2.16:
 258
 259 * Support for the R_ARM_V4BX relocation as defined in the ARM AAELF
 260   specification has been added via the --fix-v4bx command-line option.
 261
 262 * New linker script construct AS_NEEDED(), which sets the --as-needed flag
 263   for input files listed inside of it.
 264
 265 * A new command-line option, --sysroot, can be used to override the
 266   default sysroot location.  It only applies to toolchains that were
 267   configured using --with-sysroot.
 268
 269 * New linker script functions: ORIGIN() and LENGTH() which return information
 270   about a specified memory region.
 271
 272 * Port to MAXQ processor contributed by HCL Tech.
 273
 274 * Added SEGMENT_START to the linker script language to permit the user to
 275   override the base address for a segment from the command-line.
 276
 277 * ELF: --warn-shared-textrel option to warn if adding a DT_TEXTREL to a shared
 278   object.
 279
 280 * Added SORT_BY_NAME and SORT_BY_ALIGNMENT to the linker script
 281   language to permit sorting sections by section name or section
 282   maximum alignment.
 283
 284 * Added a new linker command line switch, --sort-section name|alignment,
 285   to sort sections by section name or maximum alignment.
 286
 287 * ELF: --add-needed/--no-add-needed options to control if a DT_NEEDED tag
 288   should be added when a shared library comes from DT_NEEDED tags.
 289
 290 * Support for the crx-elf target added.
 291
 292 * Support for the sh-symbianelf target added.
 293
 294 * A new linker command line switch has been added which allows the hash table
 295   size to be set to a suitable prime value near to its argument.  This switch
 296   is --hash-size=<NUMBER>.  Also if the switch --reduce-memory-overheads is
 297   used, and --hash-size has not been used, then the default value will be set
 298   to 1021.
 299
 300 * Linker map files are now generated with an O(N) algorithm for finding symbols
 301   that are defined in each section.  This uses about 40% more memory for
 302   symbols than the old O(N^2) algorithm.  You can use the new
 303   --reduce-memory-overheads option to select the old algorithm; this option
 304   might also be used in the future to select similar tradeoffs.
 305
 306 Changes in 2.15:
 307
 308 * ELF: --as-needed/--no-as-needed options to control if a DT_NEEDED tag should
 309   be added only when a shared library is referenced.
 310
 311 * PE: --large-address-aware option to indicate executables support virtual
 312   addresses greater than 2 gigabytes.
 313
 314 * DWARF 2 support for i386pe added.
 315
 316 * The linker script operator DEFINED() will now yield 1 only for a symbol that
 317   is defined before the statement where DEFINED is used.
 318
 319 * The MIPS --embedded-relocs (used to embed relocations into binaries for
 320   Embedded-PIC code) is deprecated and will be removed in a future release.
 321
 322 * cr16c support added by NSC.
 323
 324 * m32r Linux (ELF) support added by Renesas.
 325
 326 * Improved linker's handling of unresolved symbols.  The switch
 327   --unresolved-symbols=<method> has been added to tell the linker when it
 328   should report them and the switch --warn-unresolved-symbols has been added to
 329   make reports be issued as warning messages rather than errors.
 330
 331 Changes in 2.14:
 332
 333 * Added support for Xtensa architecture.
 334
 335 * Added --with-sysroot configure switch to specify a target system root, for
 336   linking against a target filesystem image.
 337
 338 * Added --accept-unknown-linker-format to restore old linker behaviour (pre
 339   2.14) of silently accepting and linking in any files in an unknown binary
 340   file format.
 341
 342 * Added --no-omagic to undo the effects of the -N option.
 343
 344 * Support for Texas Instruments TMS320C4x and TMS320C3x series of
 345   DSP's contributed by Michael Hayes and Svein E. Seldal.
 346
 347 * Added --with-lib-path configure switch to specify default value for
 348   LIB_PATH.
 349
 350 * ARM port to QNX operating system added by Graeme Peterson.
 351
 352 * IP2K support added by Denis Chertykov.
 353
 354 Changes in 2.13:
 355
 356 * Support for the Fujitsu FRV architecture added by Red Hat. Models for FR400
 357   and FR500 included.
 358
 359 Changes in version 2.13:
 360
 361 * DEC VAX ELF support, by Matt Thomas.
 362
 363 Changes in version 2.12:
 364
 365 * Support for Don Knuth's MMIX, by Hans-Peter Nilsson.
 366
 367 * Support for the OpenRISC 32-bit embedded processor by OpenCores.
 368
 369 * Support for -z nocopyreloc in the x86 ELF linker, which disables
 370   production of copy relocs.  Warning: using this option may result in
 371   non-sharable applications.
 372
 373 * Support for -z combreloc in the ELF linker, which puts dynamic
 374   relocations against the same symbol together, so that dynamic linker
 375   can use an one-entry symbol lookup cache.
 376
 377 * Support for ELF SHF_MERGE section merging, by Jakub Jelinek.
 378
 379 Changes in version 2.11:
 380
 381 * Support for AMD x86-64 architecture, by Jan Hubicka, SuSE Labs.
 382
 383 * Support added for eliminating duplicate DWARF2 debug information by
 384   having the compiler generate the information in sections called
 385   .gnu.linkonce.wi.XXXX where XXXX is a checksum for the contents.  The
 386   linker then merges these sections together into the normal .debug_info
 387   section.
 388
 389 * The native ELF linker now searches the directories in DT_RUNPATH or
 390   DT_RPATH of a shared library for shared libraries needed by it.
 391
 392 * TI C54x support, by Timothy Wall.
 393
 394 * Added command line switch --section-start to set the start address of any
 395   specified section.
 396
 397 * Added ability to emit full relocation information in linked executables,
 398   enabled by --emit-relocs.  Some post-linkage optimization tools need
 399   this information in order to be able to correctly identify and perform
 400   symbol relative addressing in the event of changes in section contents
 401   (instructions being added or deleted, extending data sections, etc.)
 402
 403 * Support for i860, by Jason Eckhardt (preliminary, alpha quality).
 404
 405 * Support for CRIS (Axis Communications ETRAX series).
 406
 407 * Support for PDP-11 and 2.11BSD a.out format, by Lars Brinkhoff.
 408
 409 Changes in version 2.10:
 410
 411 * Added AT> to the linker script language to allow load-time allocation of
 412   sections into regions.
 413
 414 * Added garbage collection of unused sections, enabled by --gc-sections.
 415   It does require a bit of backend support; currently implemented are
 416   arm-elf, avr-elf, d10v-elf, fr30-elf, i386-elf, m32r-elf, m68k-elf,
 417   mcore-elf, mips-elf, mn10300-elf, ppc-elf, sh-elf, sparc-elf, and v850-elf.
 418   Others will ignore the option.
 419
 420 * Added SORT to the linker script language to permit sorting sections by file
 421   name or section name.
 422
 423 * Added EXTERN to the linker script language as an equivalent to the -u
 424   command-line option.
 425
 426 * Added ASSERT to the linker script language.
 427
 428 * Added EXCLUDE_FILE to the linker script language for further control over
 429   wildcard file names.
 430
 431 * Added -O option to optimize linker output (as of this writing, this only
 432   affects ELF shared library generation).
 433
 434 * The -e option now accepts a number as well as a symbol name.
 435
 436 * Added --no-undefined option to disallow undefined symbols when creating a
 437   shared library.
 438
 439 * The linker now issues a warning, not an error, for an undefined symbol when
 440   using -Bsymbolic; use the new --no-undefined option to get the old
 441   behaviour.
 442
 443 * Added --demangle and --no-demangle options.
 444
 445 Changes in version 2.9:
 446
 447 * Added SQUAD to the linker script language.
 448
 449 * New option --no-warn-mismatch.
 450
 451 * The MEMORY command now parses the attributes to determine where sections that
 452   are not placed in a specific memory region are placed.
 453
 454 Changes in version 2.8:
 455
 456 * Linker scripts may now contain shell wildcard characters for file and section
 457   names.
 458
 459 * The linker now supports symbol versions in ELF.
 460
 461 * The NOCROSSREFS command was added to the linker script language.
 462
 463 * The LOADADDR expression was added to the linker script language.
 464
 465 * MAX and MIN functions were added to the linker script language.
 466
 467 * The OVERLAY construct was added to the linker script language.
 468
 469 * New option --warn-section-align to warn when the address of an output section
 470   changes due to alignment of an input section.
 471
 472 * New options --filter/-F and --auxiliary/-f.
 473
 474 Changes in version 2.7:
 475
 476 * New option --cref to print out a cross reference table.
 477
 478 * New option --wrap SYMBOL.
 479
 480 * New option --no-whole-archive, to turn off the effect of --whole-archive.
 481
 482 * Input sections assigned to the output section /DISCARD/ in the linker script
 483   are not included in the output file.
 484
 485 * The SunOS and ELF linkers now merge stabs debugging information which uses
 486   the N_BINCL and N_EINCL stab types.  This reduces the amount of debugging
 487   information generated.
 488
 489 Changes in version 2.6:
 490
 491 * When an ELF section name is representable as a C identifier (this is not true
 492 of most ELF section names), the linker will automatically define symbols
 493 __start_SECNAME and __stop_SECNAME, where SECNAME is the section name, at the
 494 beginning and the end of the section.  This is used by glibc.
 495
 496   Addendum: Current versions of the linker (at least for version 2.18 onwards
 497 and possibly much earlier as well) place two restrictions on this feature:  The
 498 symbols are only implemented for orphaned sections, not for explicitly placed
 499 sections and they are PROVIDEd rather than being defined.
 500
 501 * When an ELF section named .gnu.warning is encountered in an input file, the
 502 contents of the section are displayed as an error message, and the section is
 503 not copied into the output file.  This is used by glibc.
 504
 505 * When an ELF section named .gnu.warning.SYMBOL is encountered in an input
 506 file, and the symbol SYMBOL is referenced by some object file, the contents of
 507 the section are displayed as an error message.  The section is not copied into
 508 the output file, unless doing a relocatable or shared link.  This is used by
 509 glibc.
 510
 511 * New options -split-by-reloc and -split-by-file.
 512
 513 * The linker now supports linking PIC compiled code on SPARC SunOS.  It can
 514 also create SPARC SunOS shared libraries, and, like the native SunOS linker,
 515 will do so whenever there is an undefined symbol in the link and neither the -e
 516 nor the -r option was used.
 517
 518 * The -rpath option may be used on SunOS to set the list of directories to be
 519 searched at run time.  This overrides the default of building the list from the
 520 -L options.
 521
 522 * The COFF linker now combines debugging information for structs, unions, and
 523 enums, so that even if the same type is defined in multiple input files it will
 524 only be defined once in the output file.  The --traditional-format switch will
 525 prevent this optimization.
 526
 527 Changes in version 2.5:
 528
 529 * The linker now supports linking against SunOS shared libraries.  It still can
 530 not link SunOS PIC (Position Independent Code) files, so it can not be used to
 531 generate shared libraries.
 532
 533 * The linker now supports linking against ELF shared libraries for the i386
 534 (UnixWare) and SPARC (Solaris).  It can also link ELF PIC files, and can be
 535 used to generate shared libraries.  Shared library generation is not well
 536 tested; please report any problems encountered.  The linker is now enabled for
 537 Solaris again.
 538
 539 * Eric Youngdale has contributed Linux support code, including linking against
 540 Linux a.out shared libraries.  The linker produces Linux QMAGIC binaries.
 541
 542 * The ELF backend has been converted to the new linker code.  To use the new
 543 ELF linker, each particular target requires a relocation function.  So far,
 544 this function has been written for i386 (UnixWare), SPARC (Solaris) MIPS (Irix
 545 5), and HPPA ELF targets.
 546
 547 * The -( (--start-group) and -) (--end-group) options have been added to
 548 support searching a group of archives as though they were a single archive.
 549 This can also be used in a linker script, as GROUP ( files ).
 550
 551 * When a file is named on the command line, and the linker does not recognize
 552 it as an object file, the linker will now treat the file as a linker script
 553 file.  A linker script named in this way augments, but does not replace, the
 554 default linker script.
 555
 556 * The -warn-once option was added.  It causes the linker to only warn once per
 557 undefined symbol, rather than once per reference.
 558
 559 * The COFF backend has been converted to the new linker code.  As with ELF, to
 560 use the new linker, each particular target requires a relocation function.  So
 561 far, this function has been written for the i386, m68k, a29k and SH targets.
 562
 563 * The -V flag was made a synonym for -v, for SVR4 compatibility.  The old -V
 564 behaviour is available via --verbose.
 565
 566 Changes in version 2.4:
 567
 568 * New linker code, by Steve Chamberlain and Ian Taylor.  For a.out and ecoff
 569   formats (so far), this should result in considerable savings in time
 570   and memory used while linking; slightly poorer performance than
 571   before for formats not converted yet.
 572
 573 * Command-line parsing is no longer done with flex.  This means
 574   oddball characters in filenames won't get treated as argument
 575   separators.
 576
 577 * HP-PA ELF support, by Jeff Law.  (No SOM support yet.)
 578
 579 * Mach i386 support, by David Mackenzie.
 580
 581 * Irix 4 shared libraries are now supported (Irix 5 uses ELF, and ELF shared
 582   libraries are not yet supported).
 583
 584 * COFF shared libraries (as on SCO) should work as well.
 585
 586 * The linker is disabled for Solaris.  (Actually, it was in 2.3 also, I just
 587   forgot to note it.)  Some of their C library routines don't work when
 588   statically linked, and the GNU linker doesn't support dynamic linking yet.
 589
 590 Changes in version 2.3:
 591
 592 * Weak symbols are now supported.
 593
 594 * ELF support has been added.  The linker has been bootstrapped on
 595   UnixWare and Solaris.
 596
 597 * Alpha OSF/1 support has been added (non dynamic linking only).
 598
 599 Changes in version 2.2:
 600
 601 * The `bfd' library has been updated to reduce a.out-format string
 602   table size.  The effect of this is that files linked from many input
 603   files with duplicate symbols (`-g' debugging records, or identical
 604   static symbols) should be much smaller.
 605
 606 Changes in version 2.1:
 607
 608 * The ld -ySYMBOL flag (to trace references to SYMBOL) is now implemented.
 609
 610 * There is now support for writing ECOFF files, so ld and the
 611   other utilities should work on Risc/Ultrix and Irix.
 612
 613 \f
 614 Copyright (C) 2012-2015 Free Software Foundation, Inc.
 615
 616 Copying and distribution of this file, with or without modification,
 617 are permitted in any medium without royalty provided the copyright
 618 notice and this notice are preserved.
 619
 620 Local variables:
 621 fill-column: 79
 622 End: