ld/NEWS

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