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