ld/NEWS

   1 -*- text -*-
   2
   3 * Replace support for openrisc and or32 with support for or1k.
   4
   5 * Add support for the --build-id command line option to COFF based targets.
   6
   7 * x86/x86_64 pe-coff now supports the --build-id option.
   8
   9 * Add support for the Andes NDS32.
  10
  11 Changes in 2.24:
  12
  13 * Add LOG2CEIL() builtin function to the linker script language
  14
  15 * Add support for the Texas Instruments MSP430X processor.
  16
  17 * Add support for Altera Nios II.
  18
  19 * Add support for the V850E3V5 architecture.
  20
  21 * Add support for the Imagination Technologies Meta processor.
  22
  23 * --enable-new-dtags no longer generates old dtags in addition to new dtags.
  24
  25 * Remove linker support for MIPS ECOFF targets.
  26
  27 * Add ALIGN_WITH_INPUT to the linker script language to force the alignment of
  28   an output section to use the maximum alignment of all its input sections.
  29
  30 Changes in 2.23:
  31
  32 * Enable compressed debug section feature for x86/x86_64 pe-coff.
  33
  34 * Add support for the 64-bit ARM architecture: AArch64.
  35
  36 * Added SORT_NONE to the linker script language to disable section sorting.
  37
  38 * Add a linker-provided symbol when producing ELF output, '__ehdr_start'
  39   to point to the ELF file header (and nearby program headers) in the
  40   program's memory image.
  41
  42 * Add support for S12X processor.
  43
  44 * Add support for the VLE extension to the PowerPC architecture.
  45
  46 * Add support for the Freescale XGATE architecture.
  47
  48 * Add option -f FILE on AIX (for response file).
  49
  50 * Add support for the Renesas RL78 architecture.
  51
  52 * Add support for the Adapteva EPIPHANY architecture.
  53
  54 Changes in 2.22:
  55
  56 * --copy-dt-needed-entries is no longer enabled by default.  Instead
  57   --no-copy-dt-needed-entries is the default.
  58
  59 * INPUT_SECTION_FLAGS has been added to the linker script language
  60   to allow selection of input sections by section header section flags.
  61
  62 * Add support for the Tilera TILEPro and TILE-Gx architectures.
  63
  64 * Added SORT_BY_INIT_PRIORITY to the linker script language to permit
  65   sorting sections by numerical value of the GCC init_priority attribute
  66   encoded in the section name.
  67
  68 Changes in 2.21:
  69
  70 * Linker script expression evaluation is somewhat more sane.  This may
  71   break scripts that depend on quirks of the old expression evaluation.
  72
  73 * Turn off underscoring for x86_64 PE+-COFF targets.  For old behavior the
  74   option --enable-leading-mingw64-underscores can be used on configure of
  75   bfd.
  76
  77 * Add support for the TMS320C6000 (TI C6X) processor family.
  78
  79 * --add-needed renamed to --copy-dt-needed-entries in order to avoid confusion
  80   with --as-needed option.
  81
  82 * Extend .def file syntax by '== <ID>' for imports and exports. This allows
  83   to alias the import/export table name written in PE image.
  84
  85 * Add --exclude-all-symbols option to PE based linkers.  This prevents all
  86   symbols from automatically being exported.
  87
  88 * Add support for the Renesas RX processor.
  89
  90 * Add support for alpha-vms target.
  91
  92 Changes in 2.20:
  93
  94 * GNU/Linux targets now support the STB_GNU_UNIQUE symbol binding.  This is a
  95   GNU extension to the standard set of ELF symbol bindings.  The binding will
  96   be passed on to the dynamic linker which will make sure that in the entire
  97   process there is just one symbol with the given name and type in use.
  98
  99 * PE targets now support a GNU extension to allow the alignment of common
 100   common symbols to be specified.  This support uses custom options in
 101   the .drectve section, which will be disregarded by the native tools.
 102
 103 * PE targets now add primitive support for ELF version scripts; symbols
 104   are not versioned, but the local and global symbol visibility directives
 105   are respected when filtering symbols in auto-export mode.
 106
 107 * New option --no-export-dynamic to undo the effect of the -E and
 108   --export-dynamic options.
 109
 110 * ELF: --warn-alternate-em option to warn if an object has alternate
 111   ELF machine code.
 112
 113 * New script function REGION_ALIAS to add alias names to memory regions.
 114
 115 * PE targets no longer make use of the long section names PE extension to
 116   the COFF format when generating executable images, by default.  The old
 117   (slightly non-conformant) behaviour can still be invoked by using the
 118   new '--enable-long-section-names' command-line option.  It is also enabled
 119   automatically in the presence of un-stripped debug information, as GDB
 120   needs to be able to find the debug info sections by their full names.
 121
 122 * For GNU/Linux systems the linker will now avoid processing any relocations
 123   made against symbols of the STT_GNU_IFUNC type and instead emit them into
 124   the resulting binary for processing by the loader.
 125
 126 * --as-needed now links in a dynamic library if it satisfies undefined
 127   symbols in regular objects, or in other dynamic libraries.  In the
 128   latter case the library is not linked if it is found in a DT_NEEDED
 129   entry of one of the libraries already linked.
 130
 131 * Add a new command line option, -Ttext-segment ADDR, for ELF targets
 132   to set the address of the first byte of the text segment.
 133
 134 * Add support for Sunplus score architecture.
 135
 136 * Add new option --use-nul-prefixed-import-tables to ld for PE targets to
 137   allow fallback to old import table generation with null element prefix.
 138
 139 * Windows PE systems now support a new --exclude-modules-for-implib option,
 140   allowing users to partition object files and archive members between a DLL
 141   and its associated import library as they are generated during linking.
 142
 143 * Add support for Lattice Mico32 (lm32) architecture.
 144
 145 * Add CR16 ELF --embedded-relocs (used to embedded relocations into binaries
 146   for Embedded-PIC code) option.
 147
 148 * Add to the PE/PE+ targets the support of two different kinds of
 149   pseudo-relocations.  They can be selected by the switches
 150   --enable-runtime-pseudo-reloc-v1 and --enable-runtime-pseudo-reloc-v2.
 151   For the switch --enable-runtime-pseudo-reloc it uses for 32-bit
 152   runtime pseudo relocation version one, for 64-bit the version two.
 153
 154 Changes in 2.19:
 155
 156 * Linker scripts support a new INSERT command that makes it easier to
 157   augment the default script.
 158
 159 * Linker script input section filespecs may now specify a file within an
 160   archive by writing "archive:file".
 161
 162 * The --sort-common switch now has an optional argument which specifies the
 163   direction of sorting.
 164
 165 * The M68K linker now supports multiple GOT generation schemes controlled via
 166   the --got=<type> command line option.
 167
 168 * The ARM EABI linker will now generate stubs for function calls to symbols
 169   that are too far away.  The placement of the stubs is controlled by a new
 170   linker command line option: --stub-group-size=N.
 171
 172 Changes in 2.18:
 173
 174 * Linker sources now released under version 3 of the GNU General Public
 175   License.
 176
 177 * ELF: New --build-id option to generate a unique per-binary identifier
 178   embedded in a note section.
 179
 180 * Added support for National Semicondutor CompactRISC (ie CR16) target.
 181
 182 * -l:foo now searches the library path for a filename called foo,
 183   without converting it to libfoo.a or libfoo.so.
 184
 185 * Add a new command line option '--default-script=FILE' or '-dT FILE'
 186   which specifies a replacement for the built in, default linker
 187   script.
 188
 189 * ELF: Add -Bsymbolic-functions, --dynamic-list-cpp-new, which puts C++
 190   operator new and delete on the dynamic list, and --dynamic-list-data,
 191   builtin list for --dynamic-list, which puts global data symbols on the
 192   dynamic list.
 193
 194 * Add support for x86_64 PE+ target.
 195
 196 * Add support for Score target.
 197
 198 * ELF: Add --dynamic-list option to specify a list of global symbols
 199   whose references shouldn't be bound to the definition within the
 200   shared library, or a list of symbols which should be added to the
 201   symbol table in the executable.
 202
 203 * The default output section LMA has changed for allocatable sections from
 204   being equal to VMA, to keeping the difference between LMA and VMA the same as
 205   the previous output section in the same region.  This is a more useful
 206   default when using overlays and other cases where you specify an LMA
 207   differing from the VMA for some sections.
 208
 209 * New switch: --print-gc-sections to list any sections removed by garabge
 210   collection.
 211
 212 * ARM: Added --vfp11-denorm-fix option to work around an erratum in current
 213   VFP11 coprocessors.
 214
 215 Changes in 2.17:
 216
 217 * Support for the Infineon XC16X has been added by KPIT Cummins Infosystems.
 218
 219 * Modify the Linux linker search order to better match ld.so search order.
 220   Look for DT_NEEDED libraries in paths specified by ld.so.conf before
 221   searching the default directories, rather than vice versa.
 222   Use $prefix/etc/ld.so.conf if it exists, otherwise /etc/ld.so.conf.
 223
 224 * PE-COFF: Forward exports from DLL's can now be specified in .def files
 225   passed directly to ld.
 226
 227 * Support for the Z80 processor family has been added.
 228
 229 * Add support for the "@<file>" syntax to the command line, so that extra
 230   switches can be read from <file>.
 231
 232 Changes in 2.16:
 233
 234 * Support for the R_ARM_V4BX relocation as defined in the ARM AAELF
 235   specification has been added via the --fix-v4bx command-line option.
 236
 237 * New linker script construct AS_NEEDED(), which sets the --as-needed flag
 238   for input files listed inside of it.
 239
 240 * A new command-line option, --sysroot, can be used to override the
 241   default sysroot location.  It only applies to toolchains that were
 242   configured using --with-sysroot.
 243
 244 * New linker script functions: ORIGIN() and LENGTH() which return information
 245   about a specified memory region.
 246
 247 * Port to MAXQ processor contributed by HCL Tech.
 248
 249 * Added SEGMENT_START to the linker script language to permit the user to
 250   override the base address for a segment from the command-line.
 251
 252 * ELF: --warn-shared-textrel option to warn if adding a DT_TEXTREL to a shared
 253   object.
 254
 255 * Added SORT_BY_NAME and SORT_BY_ALIGNMENT to the linker script
 256   language to permit sorting sections by section name or section
 257   maximum alignment.
 258
 259 * Added a new linker command line switch, --sort-section name|alignment,
 260   to sort sections by section name or maximum alignment.
 261
 262 * ELF: --add-needed/--no-add-needed options to control if a DT_NEEDED tag
 263   should be added when a shared library comes from DT_NEEDED tags.
 264
 265 * Support for the crx-elf target added.
 266
 267 * Support for the sh-symbianelf target added.
 268
 269 * A new linker command line switch has been added which allows the hash table
 270   size to be set to a suitable prime value near to its argument.  This switch
 271   is --hash-size=<NUMBER>.  Also if the switch --reduce-memory-overheads is
 272   used, and --hash-size has not been used, then the default value will be set
 273   to 1021.
 274
 275 * Linker map files are now generated with an O(N) algorithm for finding symbols
 276   that are defined in each section.  This uses about 40% more memory for
 277   symbols than the old O(N^2) algorithm.  You can use the new
 278   --reduce-memory-overheads option to select the old algorithm; this option
 279   might also be used in the future to select similar tradeoffs.
 280
 281 Changes in 2.15:
 282
 283 * ELF: --as-needed/--no-as-needed options to control if a DT_NEEDED tag should
 284   be added only when a shared library is referenced.
 285
 286 * PE: --large-address-aware option to indicate executables support virtual
 287   addresses greater than 2 gigabytes.
 288
 289 * DWARF 2 support for i386pe added.
 290
 291 * The linker script operator DEFINED() will now yield 1 only for a symbol that
 292   is defined before the statement where DEFINED is used.
 293
 294 * The MIPS --embedded-relocs (used to embed relocations into binaries for
 295   Embedded-PIC code) is deprecated and will be removed in a future release.
 296
 297 * cr16c support added by NSC.
 298
 299 * m32r Linux (ELF) support added by Renesas.
 300
 301 * Improved linker's handling of unresolved symbols.  The switch
 302   --unresolved-symbols=<method> has been added to tell the linker when it
 303   should report them and the switch --warn-unresolved-symbols has been added to
 304   make reports be issued as warning messages rather than errors.
 305
 306 Changes in 2.14:
 307
 308 * Added support for Xtensa architecture.
 309
 310 * Added --with-sysroot configure switch to specify a target system root, for
 311   linking against a target filesystem image.
 312
 313 * Added --accept-unknown-linker-format to restore old linker behaviour (pre
 314   2.14) of silently accepting and linking in any files in an unknown binary
 315   file format.
 316
 317 * Added --no-omagic to undo the effects of the -N option.
 318
 319 * Support for Texas Instruments TMS320C4x and TMS320C3x series of
 320   DSP's contributed by Michael Hayes and Svein E. Seldal.
 321
 322 * Added --with-lib-path configure switch to specify default value for
 323   LIB_PATH.
 324
 325 * ARM port to QNX operating system added by Graeme Peterson.
 326
 327 * IP2K support added by Denis Chertykov.
 328
 329 Changes in 2.13:
 330
 331 * Support for the Fujitsu FRV architecture added by Red Hat. Models for FR400
 332   and FR500 included.
 333
 334 Changes in version 2.13:
 335
 336 * DEC VAX ELF support, by Matt Thomas.
 337
 338 Changes in version 2.12:
 339
 340 * Support for Don Knuth's MMIX, by Hans-Peter Nilsson.
 341
 342 * Support for the OpenRISC 32-bit embedded processor by OpenCores.
 343
 344 * Support for -z nocopyreloc in the x86 ELF linker, which disables
 345   production of copy relocs.  Warning: using this option may result in
 346   non-sharable applications.
 347
 348 * Support for -z combreloc in the ELF linker, which puts dynamic
 349   relocations against the same symbol together, so that dynamic linker
 350   can use an one-entry symbol lookup cache.
 351
 352 * Support for ELF SHF_MERGE section merging, by Jakub Jelinek.
 353
 354 Changes in version 2.11:
 355
 356 * Support for AMD x86-64 architecture, by Jan Hubicka, SuSE Labs.
 357
 358 * Support added for eliminating duplicate DWARF2 debug information by
 359   having the compiler generate the information in sections called
 360   .gnu.linkonce.wi.XXXX where XXXX is a checksum for the contents.  The
 361   linker then merges these sections together into the normal .debug_info
 362   section.
 363
 364 * The native ELF linker now searches the directories in DT_RUNPATH or
 365   DT_RPATH of a shared library for shared libraries needed by it.
 366
 367 * TI C54x support, by Timothy Wall.
 368
 369 * Added command line switch --section-start to set the start address of any
 370   specified section.
 371
 372 * Added ability to emit full relocation information in linked executables,
 373   enabled by --emit-relocs.  Some post-linkage optimization tools need
 374   this information in order to be able to correctly identify and perform
 375   symbol relative addressing in the event of changes in section contents
 376   (instructions being added or deleted, extending data sections, etc.)
 377
 378 * Support for i860, by Jason Eckhardt (preliminary, alpha quality).
 379
 380 * Support for CRIS (Axis Communications ETRAX series).
 381
 382 * Support for PDP-11 and 2.11BSD a.out format, by Lars Brinkhoff.
 383
 384 Changes in version 2.10:
 385
 386 * Added AT> to the linker script language to allow load-time allocation of
 387   sections into regions.
 388
 389 * Added garbage collection of unused sections, enabled by --gc-sections.
 390   It does require a bit of backend support; currently implemented are
 391   arm-elf, avr-elf, d10v-elf, fr30-elf, i386-elf, m32r-elf, m68k-elf,
 392   mcore-elf, mips-elf, mn10300-elf, ppc-elf, sh-elf, sparc-elf, and v850-elf.
 393   Others will ignore the option.
 394
 395 * Added SORT to the linker script language to permit sorting sections by file
 396   name or section name.
 397
 398 * Added EXTERN to the linker script language as an equivalent to the -u
 399   command-line option.
 400
 401 * Added ASSERT to the linker script language.
 402
 403 * Added EXCLUDE_FILE to the linker script language for further control over
 404   wildcard file names.
 405
 406 * Added -O option to optimize linker output (as of this writing, this only
 407   affects ELF shared library generation).
 408
 409 * The -e option now accepts a number as well as a symbol name.
 410
 411 * Added --no-undefined option to disallow undefined symbols when creating a
 412   shared library.
 413
 414 * The linker now issues a warning, not an error, for an undefined symbol when
 415   using -Bsymbolic; use the new --no-undefined option to get the old
 416   behaviour.
 417
 418 * Added --demangle and --no-demangle options.
 419
 420 Changes in version 2.9:
 421
 422 * Added SQUAD to the linker script language.
 423
 424 * New option --no-warn-mismatch.
 425
 426 * The MEMORY command now parses the attributes to determine where sections that
 427   are not placed in a specific memory region are placed.
 428
 429 Changes in version 2.8:
 430
 431 * Linker scripts may now contain shell wildcard characters for file and section
 432   names.
 433
 434 * The linker now supports symbol versions in ELF.
 435
 436 * The NOCROSSREFS command was added to the linker script language.
 437
 438 * The LOADADDR expression was added to the linker script language.
 439
 440 * MAX and MIN functions were added to the linker script language.
 441
 442 * The OVERLAY construct was added to the linker script language.
 443
 444 * New option --warn-section-align to warn when the address of an output section
 445   changes due to alignment of an input section.
 446
 447 * New options --filter/-F and --auxiliary/-f.
 448
 449 Changes in version 2.7:
 450
 451 * New option --cref to print out a cross reference table.
 452
 453 * New option --wrap SYMBOL.
 454
 455 * New option --no-whole-archive, to turn off the effect of --whole-archive.
 456
 457 * Input sections assigned to the output section /DISCARD/ in the linker script
 458   are not included in the output file.
 459
 460 * The SunOS and ELF linkers now merge stabs debugging information which uses
 461   the N_BINCL and N_EINCL stab types.  This reduces the amount of debugging
 462   information generated.
 463
 464 Changes in version 2.6:
 465
 466 * When an ELF section name is representable as a C identifier (this is not true
 467 of most ELF section names), the linker will automatically define symbols
 468 __start_SECNAME and __stop_SECNAME, where SECNAME is the section name, at the
 469 beginning and the end of the section.  This is used by glibc.
 470
 471   Addendum: Current versions of the linker (at least for version 2.18 onwards
 472 and possibly much earlier as well) place two restrictions on this feature:  The
 473 symbols are only implemented for orphaned sections, not for explicitly placed
 474 sections and they are PROVIDEd rather than being defined.
 475
 476 * When an ELF section named .gnu.warning is encountered in an input file, the
 477 contents of the section are displayed as an error message, and the section is
 478 not copied into the output file.  This is used by glibc.
 479
 480 * When an ELF section named .gnu.warning.SYMBOL is encountered in an input
 481 file, and the symbol SYMBOL is referenced by some object file, the contents of
 482 the section are displayed as an error message.  The section is not copied into
 483 the output file, unless doing a relocatable or shared link.  This is used by
 484 glibc.
 485
 486 * New options -split-by-reloc and -split-by-file.
 487
 488 * The linker now supports linking PIC compiled code on SPARC SunOS.  It can
 489 also create SPARC SunOS shared libraries, and, like the native SunOS linker,
 490 will do so whenever there is an undefined symbol in the link and neither the -e
 491 nor the -r option was used.
 492
 493 * The -rpath option may be used on SunOS to set the list of directories to be
 494 searched at run time.  This overrides the default of building the list from the
 495 -L options.
 496
 497 * The COFF linker now combines debugging information for structs, unions, and
 498 enums, so that even if the same type is defined in multiple input files it will
 499 only be defined once in the output file.  The --traditional-format switch will
 500 prevent this optimization.
 501
 502 Changes in version 2.5:
 503
 504 * The linker now supports linking against SunOS shared libraries.  It still can
 505 not link SunOS PIC (Position Independent Code) files, so it can not be used to
 506 generate shared libraries.
 507
 508 * The linker now supports linking against ELF shared libraries for the i386
 509 (UnixWare) and SPARC (Solaris).  It can also link ELF PIC files, and can be
 510 used to generate shared libraries.  Shared library generation is not well
 511 tested; please report any problems encountered.  The linker is now enabled for
 512 Solaris again.
 513
 514 * Eric Youngdale has contributed Linux support code, including linking against
 515 Linux a.out shared libraries.  The linker produces Linux QMAGIC binaries.
 516
 517 * The ELF backend has been converted to the new linker code.  To use the new
 518 ELF linker, each particular target requires a relocation function.  So far,
 519 this function has been written for i386 (UnixWare), SPARC (Solaris) MIPS (Irix
 520 5), and HPPA ELF targets.
 521
 522 * The -( (--start-group) and -) (--end-group) options have been added to
 523 support searching a group of archives as though they were a single archive.
 524 This can also be used in a linker script, as GROUP ( files ).
 525
 526 * When a file is named on the command line, and the linker does not recognize
 527 it as an object file, the linker will now treat the file as a linker script
 528 file.  A linker script named in this way augments, but does not replace, the
 529 default linker script.
 530
 531 * The -warn-once option was added.  It causes the linker to only warn once per
 532 undefined symbol, rather than once per reference.
 533
 534 * The COFF backend has been converted to the new linker code.  As with ELF, to
 535 use the new linker, each particular target requires a relocation function.  So
 536 far, this function has been written for the i386, m68k, a29k and SH targets.
 537
 538 * The -V flag was made a synonym for -v, for SVR4 compatibility.  The old -V
 539 behaviour is available via --verbose.
 540
 541 Changes in version 2.4:
 542
 543 * New linker code, by Steve Chamberlain and Ian Taylor.  For a.out and ecoff
 544   formats (so far), this should result in considerable savings in time
 545   and memory used while linking; slightly poorer performance than
 546   before for formats not converted yet.
 547
 548 * Command-line parsing is no longer done with flex.  This means
 549   oddball characters in filenames won't get treated as argument
 550   separators.
 551
 552 * HP-PA ELF support, by Jeff Law.  (No SOM support yet.)
 553
 554 * Mach i386 support, by David Mackenzie.
 555
 556 * Irix 4 shared libraries are now supported (Irix 5 uses ELF, and ELF shared
 557   libraries are not yet supported).
 558
 559 * COFF shared libraries (as on SCO) should work as well.
 560
 561 * The linker is disabled for Solaris.  (Actually, it was in 2.3 also, I just
 562   forgot to note it.)  Some of their C library routines don't work when
 563   statically linked, and the GNU linker doesn't support dynamic linking yet.
 564
 565 Changes in version 2.3:
 566
 567 * Weak symbols are now supported.
 568
 569 * ELF support has been added.  The linker has been bootstrapped on
 570   UnixWare and Solaris.
 571
 572 * Alpha OSF/1 support has been added (non dynamic linking only).
 573
 574 Changes in version 2.2:
 575
 576 * The `bfd' library has been updated to reduce a.out-format string
 577   table size.  The effect of this is that files linked from many input
 578   files with duplicate symbols (`-g' debugging records, or identical
 579   static symbols) should be much smaller.
 580
 581 Changes in version 2.1:
 582
 583 * The ld -ySYMBOL flag (to trace references to SYMBOL) is now implemented.
 584
 585 * There is now support for writing ECOFF files, so ld and the
 586   other utilities should work on Risc/Ultrix and Irix.
 587
 588 \f
 589 Copyright (C) 2012-2014 Free Software Foundation, Inc.
 590
 591 Copying and distribution of this file, with or without modification,
 592 are permitted in any medium without royalty provided the copyright
 593 notice and this notice are preserved.
 594
 595 Local variables:
 596 fill-column: 79
 597 End: