ld/NEWS

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