ld/NEWS

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