ld/NEWS

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