2004-12-14 Randolph Chung <tausq@debian.org>
[deliverable/binutils-gdb.git] / ld / NEWS
1 -*- text -*-
2
3 * New linker script functions: ORIGIN() and LENGTH() which return information
4 about a specified memory region.
5
6 * Port to MAXQ processor contributed by HCL Tech.
7
8 * Added SEGMENT_START to the linker script language to permit the user to
9 override the base address for a segment from the command-line.
10
11 * ELF: --warn-shared-textrel option to warn if adding a DT_TEXTREL to a shared
12 object.
13
14 * Added SORT_BY_NAME and SORT_BY_ALIGNMENT to the linker script
15 language to permit sorting sections by section name or section
16 maximum alignment.
17
18 * Added a new linker command line switch, --sort-section name|alignment,
19 to sort sections by section name or maximum alignment.
20
21 * ELF: --add-needed/--no-add-needed options to control if a DT_NEEDED tag
22 should be added when a shared library comes from DT_NEEDED tags.
23
24 * Support for the crx-elf target added.
25
26 * Support for the sh-symbianelf target added.
27
28 * A new linker command line switch has been added which allows the hash table
29 size to be set to a suitable prime value near to its argument. This switch
30 is --hash-size=<NUMBER>. Also if the switch --reduce-memory-overheads is
31 used, and --hash-size has not been used, then the default value will be set
32 to 1021.
33
34 * Linker map files are now generated with an O(N) algorithm for finding symbols
35 that are defined in each section. This uses about 40% more memory for
36 symbols than the old O(N^2) algorithm. You can use the new
37 --reduce-memory-overheads option to select the old algorithm; this option
38 might also be used in the future to select similar tradeoffs.
39
40 Changes in 2.15:
41
42 * ELF: --as-needed/--no-as-needed options to control if a DT_NEEDED tag should
43 be added only when a shared library is referenced.
44
45 * PE: --large-address-aware option to indicate executables support virtual
46 addresses greater than 2 gigabytes.
47
48 * DWARF 2 support for i386pe added.
49
50 * The linker script operator DEFINED() will now yield 1 only for a symbol that
51 is defined before the statement where DEFINED is used.
52
53 * The MIPS --embedded-relocs (used to embed relocations into binaries for
54 Embedded-PIC code) is deprecated and will be removed in a future release.
55
56 * cr16c support added by NSC.
57
58 * m32r Linux (ELF) support added by Renesas.
59
60 * Improved linker's handling of unresolved symbols. The switch
61 --unresolved-symbols=<method> has been added to tell the linker when it
62 should report them and the switch --warn-unresolved-symbols has been added to
63 make reports be issued as warning messages rather than errors.
64
65 Changes in 2.14:
66
67 * Added support for Xtensa architecture.
68
69 * Added --with-sysroot configure switch to specify a target system root, for
70 linking against a target filesystem image.
71
72 * Added --accept-unknown-linker-format to restore old linker behaviour (pre
73 2.14) of silently accepting and linking in any files in an unknown binary
74 file format.
75
76 * Added --no-omagic to undo the effects of the -N option.
77
78 * Support for Texas Instruments TMS320C4x and TMS320C3x series of
79 DSP's contributed by Michael Hayes and Svein E. Seldal.
80
81 * Added --with-lib-path configure switch to specify default value for
82 LIB_PATH.
83
84 * ARM port to QNX operating system added by Graeme Peterson.
85
86 * IP2K support added by Denis Chertykov.
87
88 Changes in 2.13:
89
90 * Support for the Fujitsu FRV architecture added by Red Hat. Models for FR400
91 and FR500 included.
92
93 Changes in version 2.13:
94
95 * DEC VAX ELF support, by Matt Thomas.
96
97 Changes in version 2.12:
98
99 * Support for Don Knuth's MMIX, by Hans-Peter Nilsson.
100
101 * Support for the OpenRISC 32-bit embedded processor by OpenCores.
102
103 * Support for -z nocopyreloc in the x86 ELF linker, which disables
104 production of copy relocs. Warning: using this option may result in
105 non-sharable applications.
106
107 * Support for -z combreloc in the ELF linker, which puts dynamic
108 relocations against the same symbol together, so that dynamic linker
109 can use an one-entry symbol lookup cache.
110
111 * Support for ELF SHF_MERGE section merging, by Jakub Jelinek.
112
113 Changes in version 2.11:
114
115 * Support for AMD x86-64 architecture, by Jan Hubicka, SuSE Labs.
116
117 * Support added for eliminating duplicate DWARF2 debug information by
118 having the compiler generate the information in sections called
119 .gnu.linkonce.wi.XXXX where XXXX is a checksum for the contents. The
120 linker then merges these sections together into the normal .debug_info
121 section.
122
123 * The native ELF linker now searches the directories in DT_RUNPATH or
124 DT_RPATH of a shared library for shared libraries needed by it.
125
126 * TI C54x support, by Timothy Wall.
127
128 * Added command line switch --section-start to set the start address of any
129 specified section.
130
131 * Added ability to emit full relocation information in linked executables,
132 enabled by --emit-relocs. Some post-linkage optimization tools need
133 this information in order to be able to correctly identify and perform
134 symbol relative addressing in the event of changes in section contents
135 (instructions being added or deleted, extending data sections, etc.)
136
137 * Support for i860, by Jason Eckhardt (preliminary, alpha quality).
138
139 * Support for CRIS (Axis Communications ETRAX series).
140
141 * Support for PDP-11 and 2.11BSD a.out format, by Lars Brinkhoff.
142
143 Changes in version 2.10:
144
145 * Added AT> to the linker script language to allow load-time allocation of
146 sections into regions.
147
148 * Added garbage collection of unused sections, enabled by --gc-sections.
149 It does require a bit of backend support; currently implemented are
150 arm-elf, avr-elf, d10v-elf, fr30-elf, i386-elf, m32r-elf, m68k-elf,
151 mcore-elf, mips-elf, mn10300-elf, ppc-elf, sh-elf, sparc-elf, and v850-elf.
152 Others will ignore the option.
153
154 * Added SORT to the linker script language to permit sorting sections by file
155 name or section name.
156
157 * Added EXTERN to the linker script language as an equivalent to the -u
158 command-line option.
159
160 * Added ASSERT to the linker script language.
161
162 * Added EXCLUDE_FILE to the linker script language for further control over
163 wildcard file names.
164
165 * Added -O option to optimize linker output (as of this writing, this only
166 affects ELF shared library generation).
167
168 * The -e option now accepts a number as well as a symbol name.
169
170 * Added --no-undefined option to disallow undefined symbols when creating a
171 shared library.
172
173 * The linker now issues a warning, not an error, for an undefined symbol when
174 using -Bsymbolic; use the new --no-undefined option to get the old
175 behaviour.
176
177 * Added --demangle and --no-demangle options.
178
179 Changes in version 2.9:
180
181 * Added SQUAD to the linker script language.
182
183 * New option --no-warn-mismatch.
184
185 * The MEMORY command now parses the attributes to determine where sections that
186 are not placed in a specific memory region are placed.
187
188 Changes in version 2.8:
189
190 * Linker scripts may now contain shell wildcard characters for file and section
191 names.
192
193 * The linker now supports symbol versions in ELF.
194
195 * The NOCROSSREFS command was added to the linker script language.
196
197 * The LOADADDR expression was added to the linker script language.
198
199 * MAX and MIN functions were added to the linker script language.
200
201 * The OVERLAY construct was added to the linker script language.
202
203 * New option --warn-section-align to warn when the address of an output section
204 changes due to alignment of an input section.
205
206 * New options --filter/-F and --auxiliary/-f.
207
208 Changes in version 2.7:
209
210 * New option --cref to print out a cross reference table.
211
212 * New option --wrap SYMBOL.
213
214 * New option --no-whole-archive, to turn off the effect of --whole-archive.
215
216 * Input sections assigned to the output section /DISCARD/ in the linker script
217 are not included in the output file.
218
219 * The SunOS and ELF linkers now merge stabs debugging information which uses
220 the N_BINCL and N_EINCL stab types. This reduces the amount of debugging
221 information generated.
222
223 Changes in version 2.6:
224
225 * When an ELF section name is representable as a C identifier (this is not true
226 of most ELF section names), the linker will automatically define symbols
227 __start_SECNAME and __stop_SECNAME, where SECNAME is the section name, at the
228 beginning and the end of the section. This is used by glibc.
229
230 * When an ELF section named .gnu.warning is encountered in an input file, the
231 contents of the section are displayed as an error message, and the section is
232 not copied into the output file. This is used by glibc.
233
234 * When an ELF section named .gnu.warning.SYMBOL is encountered in an input
235 file, and the symbol SYMBOL is referenced by some object file, the contents of
236 the section are displayed as an error message. The section is not copied into
237 the output file, unless doing a relocatable or shared link. This is used by
238 glibc.
239
240 * New options -split-by-reloc and -split-by-file.
241
242 * The linker now supports linking PIC compiled code on SPARC SunOS. It can
243 also create SPARC SunOS shared libraries, and, like the native SunOS linker,
244 will do so whenever there is an undefined symbol in the link and neither the -e
245 nor the -r option was used.
246
247 * The -rpath option may be used on SunOS to set the list of directories to be
248 searched at run time. This overrides the default of building the list from the
249 -L options.
250
251 * The COFF linker now combines debugging information for structs, unions, and
252 enums, so that even if the same type is defined in multiple input files it will
253 only be defined once in the output file. The --traditional-format switch will
254 prevent this optimization.
255
256 Changes in version 2.5:
257
258 * The linker now supports linking against SunOS shared libraries. It still can
259 not link SunOS PIC (Position Independent Code) files, so it can not be used to
260 generate shared libraries.
261
262 * The linker now supports linking against ELF shared libraries for the i386
263 (UnixWare) and SPARC (Solaris). It can also link ELF PIC files, and can be
264 used to generate shared libraries. Shared library generation is not well
265 tested; please report any problems encountered. The linker is now enabled for
266 Solaris again.
267
268 * Eric Youngdale has contributed Linux support code, including linking against
269 Linux a.out shared libraries. The linker produces Linux QMAGIC binaries.
270
271 * The ELF backend has been converted to the new linker code. To use the new
272 ELF linker, each particular target requires a relocation function. So far,
273 this function has been written for i386 (UnixWare), SPARC (Solaris) MIPS (Irix
274 5), and HPPA ELF targets.
275
276 * The -( (--start-group) and -) (--end-group) options have been added to
277 support searching a group of archives as though they were a single archive.
278 This can also be used in a linker script, as GROUP ( files ).
279
280 * When a file is named on the command line, and the linker does not recognize
281 it as an object file, the linker will now treat the file as a linker script
282 file. A linker script named in this way augments, but does not replace, the
283 default linker script.
284
285 * The -warn-once option was added. It causes the linker to only warn once per
286 undefined symbol, rather than once per reference.
287
288 * The COFF backend has been converted to the new linker code. As with ELF, to
289 use the new linker, each particular target requires a relocation function. So
290 far, this function has been written for the i386, m68k, a29k and SH targets.
291
292 * The -V flag was made a synonym for -v, for SVR4 compatibility. The old -V
293 behaviour is available via --verbose.
294
295 Changes in version 2.4:
296
297 * New linker code, by Steve Chamberlain and Ian Taylor. For a.out and ecoff
298 formats (so far), this should result in considerable savings in time
299 and memory used while linking; slightly poorer performance than
300 before for formats not converted yet.
301
302 * Command-line parsing is no longer done with flex. This means
303 oddball characters in filenames won't get treated as argument
304 separators.
305
306 * HP-PA ELF support, by Jeff Law. (No SOM support yet.)
307
308 * Mach i386 support, by David Mackenzie.
309
310 * Irix 4 shared libraries are now supported (Irix 5 uses ELF, and ELF shared
311 libraries are not yet supported).
312
313 * COFF shared libraries (as on SCO) should work as well.
314
315 * The linker is disabled for Solaris. (Actually, it was in 2.3 also, I just
316 forgot to note it.) Some of their C library routines don't work when
317 statically linked, and the GNU linker doesn't support dynamic linking yet.
318
319 Changes in version 2.3:
320
321 * Weak symbols are now supported.
322
323 * ELF support has been added. The linker has been bootstrapped on
324 UnixWare and Solaris.
325
326 * Alpha OSF/1 support has been added (non dynamic linking only).
327
328 Changes in version 2.2:
329
330 * The `bfd' library has been updated to reduce a.out-format string
331 table size. The effect of this is that files linked from many input
332 files with duplicate symbols (`-g' debugging records, or identical
333 static symbols) should be much smaller.
334
335 Changes in version 2.1:
336
337 * The ld -ySYMBOL flag (to trace references to SYMBOL) is now implemented.
338
339 * There is now support for writing ECOFF files, so ld and the
340 other utilities should work on Risc/Ultrix and Irix.
341
342 \f
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