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