ld/NEWS

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