ld/NEWS

   1 -*- text -*-
   2
   3 * Support for the R_ARM_V4BX relocation as defined in the ARM AAELF
   4   specification has been added via the --fix-v4bx command-line option.
   5
   6 * New linker script construct AS_NEEDED(), which sets the --as-needed flag
   7   for input files listed inside of it.
   8
   9 * A new command-line option, --sysroot, can be used to override the
  10   default sysroot location.  It only applies to toolchains that were
  11   configured using --with-sysroot.
  12
  13 * New linker script functions: ORIGIN() and LENGTH() which return information
  14   about a specified memory region.
  15
  16 * Port to MAXQ processor contributed by HCL Tech.
  17
  18 * Added SEGMENT_START to the linker script language to permit the user to
  19   override the base address for a segment from the command-line.
  20
  21 * ELF: --warn-shared-textrel option to warn if adding a DT_TEXTREL to a shared
  22   object.
  23
  24 * Added SORT_BY_NAME and SORT_BY_ALIGNMENT to the linker script
  25   language to permit sorting sections by section name or section
  26   maximum alignment.
  27
  28 * Added a new linker command line switch, --sort-section name|alignment,
  29   to sort sections by section name or maximum alignment.
  30
  31 * ELF: --add-needed/--no-add-needed options to control if a DT_NEEDED tag
  32   should be added when a shared library comes from DT_NEEDED tags.
  33
  34 * Support for the crx-elf target added.
  35
  36 * Support for the sh-symbianelf target added.
  37
  38 * A new linker command line switch has been added which allows the hash table
  39   size to be set to a suitable prime value near to its argument.  This switch
  40   is --hash-size=<NUMBER>.  Also if the switch --reduce-memory-overheads is
  41   used, and --hash-size has not been used, then the default value will be set
  42   to 1021.
  43
  44 * Linker map files are now generated with an O(N) algorithm for finding symbols
  45   that are defined in each section.  This uses about 40% more memory for
  46   symbols than the old O(N^2) algorithm.  You can use the new
  47   --reduce-memory-overheads option to select the old algorithm; this option
  48   might also be used in the future to select similar tradeoffs.
  49
  50 Changes in 2.15:
  51
  52 * ELF: --as-needed/--no-as-needed options to control if a DT_NEEDED tag should
  53   be added only when a shared library is referenced.
  54
  55 * PE: --large-address-aware option to indicate executables support virtual
  56   addresses greater than 2 gigabytes.
  57
  58 * DWARF 2 support for i386pe added.
  59
  60 * The linker script operator DEFINED() will now yield 1 only for a symbol that
  61   is defined before the statement where DEFINED is used.
  62
  63 * The MIPS --embedded-relocs (used to embed relocations into binaries for
  64   Embedded-PIC code) is deprecated and will be removed in a future release.
  65
  66 * cr16c support added by NSC.
  67
  68 * m32r Linux (ELF) support added by Renesas.
  69
  70 * Improved linker's handling of unresolved symbols.  The switch
  71   --unresolved-symbols=<method> has been added to tell the linker when it
  72   should report them and the switch --warn-unresolved-symbols has been added to
  73   make reports be issued as warning messages rather than errors.
  74
  75 Changes in 2.14:
  76
  77 * Added support for Xtensa architecture.
  78
  79 * Added --with-sysroot configure switch to specify a target system root, for
  80   linking against a target filesystem image.
  81
  82 * Added --accept-unknown-linker-format to restore old linker behaviour (pre
  83   2.14) of silently accepting and linking in any files in an unknown binary
  84   file format.
  85
  86 * Added --no-omagic to undo the effects of the -N option.
  87
  88 * Support for Texas Instruments TMS320C4x and TMS320C3x series of
  89   DSP's contributed by Michael Hayes and Svein E. Seldal.
  90
  91 * Added --with-lib-path configure switch to specify default value for
  92   LIB_PATH.
  93
  94 * ARM port to QNX operating system added by Graeme Peterson.
  95
  96 * IP2K support added by Denis Chertykov.
  97
  98 Changes in 2.13:
  99
 100 * Support for the Fujitsu FRV architecture added by Red Hat. Models for FR400
 101   and FR500 included.
 102
 103 Changes in version 2.13:
 104
 105 * DEC VAX ELF support, by Matt Thomas.
 106
 107 Changes in version 2.12:
 108
 109 * Support for Don Knuth's MMIX, by Hans-Peter Nilsson.
 110
 111 * Support for the OpenRISC 32-bit embedded processor by OpenCores.
 112
 113 * Support for -z nocopyreloc in the x86 ELF linker, which disables
 114   production of copy relocs.  Warning: using this option may result in
 115   non-sharable applications.
 116
 117 * Support for -z combreloc in the ELF linker, which puts dynamic
 118   relocations against the same symbol together, so that dynamic linker
 119   can use an one-entry symbol lookup cache.
 120
 121 * Support for ELF SHF_MERGE section merging, by Jakub Jelinek.
 122
 123 Changes in version 2.11:
 124
 125 * Support for AMD x86-64 architecture, by Jan Hubicka, SuSE Labs.
 126
 127 * Support added for eliminating duplicate DWARF2 debug information by
 128   having the compiler generate the information in sections called
 129   .gnu.linkonce.wi.XXXX where XXXX is a checksum for the contents.  The
 130   linker then merges these sections together into the normal .debug_info
 131   section.
 132
 133 * The native ELF linker now searches the directories in DT_RUNPATH or
 134   DT_RPATH of a shared library for shared libraries needed by it.
 135
 136 * TI C54x support, by Timothy Wall.
 137
 138 * Added command line switch --section-start to set the start address of any
 139   specified section.
 140
 141 * Added ability to emit full relocation information in linked executables,
 142   enabled by --emit-relocs.  Some post-linkage optimization tools need
 143   this information in order to be able to correctly identify and perform
 144   symbol relative addressing in the event of changes in section contents
 145   (instructions being added or deleted, extending data sections, etc.)
 146
 147 * Support for i860, by Jason Eckhardt (preliminary, alpha quality).
 148
 149 * Support for CRIS (Axis Communications ETRAX series).
 150
 151 * Support for PDP-11 and 2.11BSD a.out format, by Lars Brinkhoff.
 152
 153 Changes in version 2.10:
 154
 155 * Added AT> to the linker script language to allow load-time allocation of
 156   sections into regions.
 157
 158 * Added garbage collection of unused sections, enabled by --gc-sections.
 159   It does require a bit of backend support; currently implemented are
 160   arm-elf, avr-elf, d10v-elf, fr30-elf, i386-elf, m32r-elf, m68k-elf,
 161   mcore-elf, mips-elf, mn10300-elf, ppc-elf, sh-elf, sparc-elf, and v850-elf.
 162   Others will ignore the option.
 163
 164 * Added SORT to the linker script language to permit sorting sections by file
 165   name or section name.
 166
 167 * Added EXTERN to the linker script language as an equivalent to the -u
 168   command-line option.
 169
 170 * Added ASSERT to the linker script language.
 171
 172 * Added EXCLUDE_FILE to the linker script language for further control over
 173   wildcard file names.
 174
 175 * Added -O option to optimize linker output (as of this writing, this only
 176   affects ELF shared library generation).
 177
 178 * The -e option now accepts a number as well as a symbol name.
 179
 180 * Added --no-undefined option to disallow undefined symbols when creating a
 181   shared library.
 182
 183 * The linker now issues a warning, not an error, for an undefined symbol when
 184   using -Bsymbolic; use the new --no-undefined option to get the old
 185   behaviour.
 186
 187 * Added --demangle and --no-demangle options.
 188
 189 Changes in version 2.9:
 190
 191 * Added SQUAD to the linker script language.
 192
 193 * New option --no-warn-mismatch.
 194
 195 * The MEMORY command now parses the attributes to determine where sections that
 196   are not placed in a specific memory region are placed.
 197
 198 Changes in version 2.8:
 199
 200 * Linker scripts may now contain shell wildcard characters for file and section
 201   names.
 202
 203 * The linker now supports symbol versions in ELF.
 204
 205 * The NOCROSSREFS command was added to the linker script language.
 206
 207 * The LOADADDR expression was added to the linker script language.
 208
 209 * MAX and MIN functions were added to the linker script language.
 210
 211 * The OVERLAY construct was added to the linker script language.
 212
 213 * New option --warn-section-align to warn when the address of an output section
 214   changes due to alignment of an input section.
 215
 216 * New options --filter/-F and --auxiliary/-f.
 217
 218 Changes in version 2.7:
 219
 220 * New option --cref to print out a cross reference table.
 221
 222 * New option --wrap SYMBOL.
 223
 224 * New option --no-whole-archive, to turn off the effect of --whole-archive.
 225
 226 * Input sections assigned to the output section /DISCARD/ in the linker script
 227   are not included in the output file.
 228
 229 * The SunOS and ELF linkers now merge stabs debugging information which uses
 230   the N_BINCL and N_EINCL stab types.  This reduces the amount of debugging
 231   information generated.
 232
 233 Changes in version 2.6:
 234
 235 * When an ELF section name is representable as a C identifier (this is not true
 236 of most ELF section names), the linker will automatically define symbols
 237 __start_SECNAME and __stop_SECNAME, where SECNAME is the section name, at the
 238 beginning and the end of the section.  This is used by glibc.
 239
 240 * When an ELF section named .gnu.warning is encountered in an input file, the
 241 contents of the section are displayed as an error message, and the section is
 242 not copied into the output file.  This is used by glibc.
 243
 244 * When an ELF section named .gnu.warning.SYMBOL is encountered in an input
 245 file, and the symbol SYMBOL is referenced by some object file, the contents of
 246 the section are displayed as an error message.  The section is not copied into
 247 the output file, unless doing a relocatable or shared link.  This is used by
 248 glibc.
 249
 250 * New options -split-by-reloc and -split-by-file.
 251
 252 * The linker now supports linking PIC compiled code on SPARC SunOS.  It can
 253 also create SPARC SunOS shared libraries, and, like the native SunOS linker,
 254 will do so whenever there is an undefined symbol in the link and neither the -e
 255 nor the -r option was used.
 256
 257 * The -rpath option may be used on SunOS to set the list of directories to be
 258 searched at run time.  This overrides the default of building the list from the
 259 -L options.
 260
 261 * The COFF linker now combines debugging information for structs, unions, and
 262 enums, so that even if the same type is defined in multiple input files it will
 263 only be defined once in the output file.  The --traditional-format switch will
 264 prevent this optimization.
 265
 266 Changes in version 2.5:
 267
 268 * The linker now supports linking against SunOS shared libraries.  It still can
 269 not link SunOS PIC (Position Independent Code) files, so it can not be used to
 270 generate shared libraries.
 271
 272 * The linker now supports linking against ELF shared libraries for the i386
 273 (UnixWare) and SPARC (Solaris).  It can also link ELF PIC files, and can be
 274 used to generate shared libraries.  Shared library generation is not well
 275 tested; please report any problems encountered.  The linker is now enabled for
 276 Solaris again.
 277
 278 * Eric Youngdale has contributed Linux support code, including linking against
 279 Linux a.out shared libraries.  The linker produces Linux QMAGIC binaries.
 280
 281 * The ELF backend has been converted to the new linker code.  To use the new
 282 ELF linker, each particular target requires a relocation function.  So far,
 283 this function has been written for i386 (UnixWare), SPARC (Solaris) MIPS (Irix
 284 5), and HPPA ELF targets.
 285
 286 * The -( (--start-group) and -) (--end-group) options have been added to
 287 support searching a group of archives as though they were a single archive.
 288 This can also be used in a linker script, as GROUP ( files ).
 289
 290 * When a file is named on the command line, and the linker does not recognize
 291 it as an object file, the linker will now treat the file as a linker script
 292 file.  A linker script named in this way augments, but does not replace, the
 293 default linker script.
 294
 295 * The -warn-once option was added.  It causes the linker to only warn once per
 296 undefined symbol, rather than once per reference.
 297
 298 * The COFF backend has been converted to the new linker code.  As with ELF, to
 299 use the new linker, each particular target requires a relocation function.  So
 300 far, this function has been written for the i386, m68k, a29k and SH targets.
 301
 302 * The -V flag was made a synonym for -v, for SVR4 compatibility.  The old -V
 303 behaviour is available via --verbose.
 304
 305 Changes in version 2.4:
 306
 307 * New linker code, by Steve Chamberlain and Ian Taylor.  For a.out and ecoff
 308   formats (so far), this should result in considerable savings in time
 309   and memory used while linking; slightly poorer performance than
 310   before for formats not converted yet.
 311
 312 * Command-line parsing is no longer done with flex.  This means
 313   oddball characters in filenames won't get treated as argument
 314   separators.
 315
 316 * HP-PA ELF support, by Jeff Law.  (No SOM support yet.)
 317
 318 * Mach i386 support, by David Mackenzie.
 319
 320 * Irix 4 shared libraries are now supported (Irix 5 uses ELF, and ELF shared
 321   libraries are not yet supported).
 322
 323 * COFF shared libraries (as on SCO) should work as well.
 324
 325 * The linker is disabled for Solaris.  (Actually, it was in 2.3 also, I just
 326   forgot to note it.)  Some of their C library routines don't work when
 327   statically linked, and the GNU linker doesn't support dynamic linking yet.
 328
 329 Changes in version 2.3:
 330
 331 * Weak symbols are now supported.
 332
 333 * ELF support has been added.  The linker has been bootstrapped on
 334   UnixWare and Solaris.
 335
 336 * Alpha OSF/1 support has been added (non dynamic linking only).
 337
 338 Changes in version 2.2:
 339
 340 * The `bfd' library has been updated to reduce a.out-format string
 341   table size.  The effect of this is that files linked from many input
 342   files with duplicate symbols (`-g' debugging records, or identical
 343   static symbols) should be much smaller.
 344
 345 Changes in version 2.1:
 346
 347 * The ld -ySYMBOL flag (to trace references to SYMBOL) is now implemented.
 348
 349 * There is now support for writing ECOFF files, so ld and the
 350   other utilities should work on Risc/Ultrix and Irix.
 351
 352 \f
 353 Local variables:
 354 fill-column: 79
 355 End: