/[gentoo]/xml/htdocs/doc/en/gcc-upgrading.xml
Gentoo

Contents of /xml/htdocs/doc/en/gcc-upgrading.xml

Parent Directory Parent Directory | Revision Log Revision Log


Revision 1.5 - (show annotations) (download) (as text)
Mon Jan 30 15:32:52 2006 UTC (8 years, 5 months ago) by jkt
Branch: MAIN
Changes since 1.4: +10 -3 lines
File MIME type: application/xml
#120164: add a warning about migrating from 3.3 to 3.4 on SPARC

1 <?xml version='1.0' encoding="UTF-8"?>
2 <!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/gcc-upgrading.xml,v 1.4 2005/12/14 20:03:44 jkt Exp $ -->
3
4 <!DOCTYPE guide SYSTEM "/dtd/guide.dtd">
5
6 <guide link="/doc/en/gcc-upgrading.xml">
7 <title>Gentoo Linux GCC Upgrade Guide</title>
8
9 <author title="Author">
10 <mail link="amne@gentoo.org">Wernfried Haas</mail>
11 </author>
12 <author title="Author">
13 <mail link="jkt@gentoo.org">Jan Kundrát</mail>
14 </author>
15 <author title="Editor">
16 <mail link="halcy0n@gentoo.org">Mark Loeser</mail>
17 </author>
18
19
20 <abstract>
21 This document will guide the user through the process of upgrading GCC on their
22 Gentoo Linux machines.
23 </abstract>
24
25 <!-- The content of this document is licensed under the CC-BY-SA license -->
26 <!-- See http://creativecommons.org/licenses/by-sa/2.5 -->
27 <license/>
28
29 <version>4</version>
30 <date>2006-01-30</date>
31
32 <chapter id="intro">
33 <title>Introduction</title>
34 <section>
35 <title>GCC Upgrading</title>
36 <body>
37
38 <p>
39 Why should you upgrade? Well, GCC is quite similar to any other package on your
40 system, just a bit more critical. You should upgrade GCC whenever a new version
41 fixes some bug that annoys you, new functionality you need is introduced, or if
42 you want to keep your system up-to-date. If none of the previous cases apply to
43 you, you can safely postpone upgrade as long as your GCC version is supported by
44 Gentoo developers.
45 </p>
46
47 <p>
48 If you install a newer version of GCC, the system will not switch over to use it
49 automatically. You'll have to explicitly request the change because the
50 migration process might require some additional steps. If you decide not to
51 switch, Portage will continue to use older version of your compiler until you
52 change your mind, or remove the old compiler from the system.
53 </p>
54
55 <p>
56 This guide will document the necessary steps required to perform a seamless
57 upgrade of the compiler used by your Gentoo box. A specific section is dedicated
58 to the <uri link="#upgrade-3.3-to-3.4">upgrade from GCC 3.3 to the 3.4
59 version</uri> and issues with <c>libstdc++</c>.
60 </p>
61
62 </body>
63 </section>
64 </chapter>
65
66 <chapter id="upgrade-general">
67 <title>General Upgrade Instructions</title>
68 <section>
69 <title>Introduction</title>
70 <body>
71
72 <impo>
73 If you're looking for instructions specific to upgrades from GCC-3.3 to
74 GCC-3.4, please consult the <uri link="#upgrade-3.3-to-3.4">dedicated
75 section</uri>.
76 </impo>
77
78 <p>
79 Generally speaking, upgrades to <e>bug fix releases</e>, like from 3.3.5 to
80 3.3.6, should be quite safe -- just emerge new version, switch your system to
81 use it and rebuild the only affected package, <c>libtool</c>. However, some GCC
82 upgrades break binary compatibility; in such cases a rebuild of the affected
83 packages (or even whole toolchain and system) might be required.
84 </p>
85
86 <p>
87 When we spoke about the need to switch your compiler to the newer version by
88 hand, we said it won't happen automatically. However, there is one exception --
89 upgrades to bug fix releases, like from 3.3.5 to 3.3.6 in case you don't use the
90 "multislot" feature allowing them to coexist on one system. Multislot is
91 disabled by default as the majority of users won't benefit from it.
92 </p>
93
94 <pre caption="Upgrading GCC">
95 # <i>emerge -uav gcc</i>
96
97 <comment>(Please substitute "i686-pc-linux-gnu-3.4.4" with the GCC
98 version and CHOST settings you've upgraded to:)</comment>
99 # <i>gcc-config i686-pc-linux-gnu-3.4.4</i>
100 # <i>source /etc/profile</i>
101
102 <comment>(Rebuilding libtool)</comment>
103 # <i>emerge --oneshot -av libtool</i>
104 </pre>
105
106 <p>
107 Now let's rebuild toolchain and then world so we will make use of the new
108 compiler.
109 </p>
110
111 <pre caption="Rebuilding system">
112 # <i>emerge -eav system</i>
113 # <i>emerge -eav world</i>
114 </pre>
115
116 <p>
117 It is safe to remove older GCC version at this time. If you feel the
118 need, please issue the following command (as usual, substitute
119 <c>=sys-devel/gcc-3.3*</c> with the version you want to uninstall):
120 </p>
121
122 <pre caption="Removing older GCC version">
123 # <i>emerge -aC =sys-devel/gcc-3.3*</i>
124 </pre>
125
126 </body>
127 </section>
128 </chapter>
129
130 <chapter id="upgrade-3.3-to-3.4">
131 <title>Upgrading from GCC-3.3 to 3.4</title>
132 <section>
133 <title>Introduction</title>
134 <body>
135
136 <p>
137 The upgrade from GCC/3.3 to 3.4 is not so seamless as the C++ ABI changed
138 between these two versions so there is an issue with <c>libstdc++</c> library
139 which must be taken care of as well.
140 </p>
141
142 </body>
143 </section>
144 <section id="upgrade-3.3-to-3.4-choices">
145 <title>The Choices</title>
146 <body>
147
148 <impo>
149 If you're upgrading on a SPARC machine, you will have to take the way of
150 <uri link="#upgrade-3.3-to-3.4-emerge-e">complete system rebuild</uri> due to
151 some internal <uri link="http://gcc.gnu.org/gcc-3.4/sparc-abi.html">ABI
152 changes</uri> in GCC's parameter passing.
153 </impo>
154
155 <p>
156 You have two possibilities on how to upgrade your system. <uri
157 link="#upgrade-3.3-to-3.4-revdep-rebuild">First method</uri> is faster and
158 requires use of <c>revdep-rebuild</c> tool from package <c>gentoolkit</c> while
159 the <uri link="#upgrade-3.3-to-3.4-emerge-e">second one</uri> rebuilds the
160 entire system from scratch so it will make use of new GCC features. It's up to
161 you to decide which of these two ways you will choose.
162 </p>
163
164 </body>
165 </section>
166 <section id="upgrade-3.3-to-3.4-revdep-rebuild">
167 <title>Using revdep-rebuild</title>
168 <body>
169
170 <p>
171 This method requires that you first install <c>gentoolkit</c> if you have not
172 already done so. Then we will upgrade GCC and switch to the new compiler. We
173 will also rebuild the <c>libtool</c> package to ensure that toolchain is in
174 healthy state.
175 </p>
176
177 <pre caption="Installing gentoolkit and upgrading GCC">
178 # <i>emerge -an gentoolkit</i>
179 # <i>emerge -uav gcc</i>
180 # <i>gcc-config i686-pc-linux-gnu-3.4.4</i>
181 # <i>source /etc/profile</i>
182
183 <comment>(Rebuilding libtool)</comment>
184 # <i>emerge --oneshot -av libtool</i>
185 </pre>
186
187 <note>
188 This assumes that you have <c>CHOST="i686-pc-linux-gnu"</c> set. If you are
189 using another CHOST, please use the appropriate gcc-config line.
190 </note>
191
192 <p>
193 Now, we want to see which packages that revdep-rebuild will want to rebuild.
194 Then we will tell revdep-rebuild to actually rebuild the packages. This may take
195 some time, so have some patience.
196 </p>
197
198 <pre caption="Using revdep-rebuild">
199 # <i>revdep-rebuild --library libstdc++.so.5 -- -p -v</i>
200 # <i>revdep-rebuild --library libstdc++.so.5</i>
201 </pre>
202
203 <note>
204 It is possible that you might have problems with non-existing package versions
205 due to them being outdated or masked. If this is the case, you will want to use
206 the <c>--package-names</c> option to <c>revdep-rebuild</c>. This causes packages
207 to be recompiled based on the package name, rather than the exact name and
208 version.
209 </note>
210
211 <p>
212 To provide compatibility with older binary C++ applications and any packages
213 that revdep-rebuild might have missed, <c>sys-libs/libstdc++-v3</c> needs to be
214 merged before you unmerge GCC 3.3 from your system.
215 </p>
216
217 <pre caption="Installing libstdc++-v3 and cleaning up">
218 # <i>emerge --oneshot sys-libs/libstdc++-v3</i>
219 # <i>emerge -aC =sys-devel/gcc-3.3*</i>
220 </pre>
221
222 </body>
223 </section>
224 <section id="upgrade-3.3-to-3.4-emerge-e">
225 <title>Using emerge -e</title>
226 <body>
227
228 <p>
229 This method, while much slower, will rebuild your whole system to ensure that
230 everything has been rebuilt with your new compiler, and therefore safer. At
231 first, you will upgrade GCC and libtool and switch to your new compiler.
232 </p>
233
234 <pre caption="Upgrading GCC">
235 # <i>emerge -uav gcc</i>
236 # <i>gcc-config i686-pc-linux-gnu-3.4.4</i>
237 # <i>source /etc/profile</i>
238
239 <comment>(Rebuilding libtool)</comment>
240 # <i>emerge --oneshot -av libtool</i>
241 </pre>
242
243 <note>
244 This assumes that you have <c>CHOST="i686-pc-linux-gnu"</c> set. If you are
245 using another CHOST, please use the appropriate gcc-config line.
246 </note>
247
248 <p>
249 To provide compatibility with older binary C++ applications,
250 <c>sys-libs/libstdc++-v3</c> needs to be merged onto your system.
251 </p>
252
253 <pre caption="Installing libstdc++-v3">
254 # <i>emerge --oneshot sys-libs/libstdc++-v3</i>
255 </pre>
256
257 <p>
258 Now we will go about first rebuilding the system target, then the world target.
259 This will take a very long time, depending on the number of packages that you
260 have installed, as it will rebuild your entire toolchain and supporting system
261 files, followed by every package on your system, including the toolchain. This
262 is necessary to ensure that all packages have been compiled with the new
263 toolchain, including the toolchain itself.
264 </p>
265
266 <pre caption="Rebuilding system and world">
267 # <i>emerge -e system</i>
268 # <i>emerge -e world</i>
269 </pre>
270
271 <p>
272 It is also safe to remove older GCC versions at this time:
273 </p>
274
275 <pre caption="Cleaning up">
276 # <i>emerge -aC =sys-devel/gcc-3.3*</i>
277 </pre>
278
279 </body>
280 </section>
281 </chapter>
282
283 <chapter id="common-pitfalls">
284 <title>Common Pitfalls</title>
285 <section>
286 <body>
287
288 <p>
289 It's important to disable <c>distcc</c> during upgrade. Mixing compiler versions
290 on your nodes <e>will</e> cause build issues. This is not required for ccache,
291 as the cache objects will be invalidated anyway.
292 </p>
293
294 <p>
295 Always use same GCC version for your kernel and additional kernel modules. Once
296 you rebuild your world with new GCC, external modules (like
297 <c>app-emulation/qemu-softmmu</c>) will fail to load. Please rebuild your kernel
298 with new GCC to fix that.
299 </p>
300
301 </body>
302 </section>
303 <section>
304 <title>Frequent Error Messages</title>
305 <body>
306
307 <p>
308 If your system complains about something like <e>libtool: link:
309 `/usr/lib/gcc-lib/i686-pc-linux-gnu/3.3.6/libstdc++.la' is not a valid libtool
310 archive</e>, please run <c>/sbin/fix_libtool_files.sh 3.3.6</c> (substitute
311 "3.3.6" with the version numbers from the error message).
312 </p>
313
314 <p>
315 If you see the <e>error: /usr/bin/gcc-config: line 632:
316 /etc/env.d/gcc/i686-pc-linux-gnu-3.3.5: No such file or directory</e>, then try
317 deleting <path>/etc/env.d/gcc/config-i686-pc-linux-gnu</path> and running
318 <c>gcc-config</c> again, followed by <c>source /etc/profile</c>. Only do this if
319 you do not have any cross-compilers set up, though.
320 </p>
321
322 <p>
323 If a package fails during <c>emerge -e system/world</c>, you can resume
324 operation with <c>emerge --resume</c>. If a package fails repeatedly, skip it
325 with <c>emerge --resume --skipfirst</c>. Don't run any other instances of emerge
326 in between or you will lose the resume information.
327 </p>
328
329 <p>
330 If you get an error message <e>spec failure: unrecognized spec option</e> while
331 upgrading your compiler, try to switch back to your default compiler, unset the
332 <c>GCC_SPECS</c> variable and upgrade GCC again:
333 </p>
334
335 <pre caption="Restoring primary specs">
336 # <i>gcc-config 1</i>
337 # <i>source /etc/profile</i>
338 # <i>unset GCC_SPECS</i>
339 # <i>emerge -uav gcc</i>
340 </pre>
341
342 </body>
343 </section>
344
345 </chapter>
346 </guide>

  ViewVC Help
Powered by ViewVC 1.1.20