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1 jkt 1.1 <?xml version='1.0' encoding="UTF-8"?>
2 jkt 1.22 <!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/gcc-upgrading.xml,v 1.21 2006/09/13 14:42:58 jkt Exp $ -->
3 jkt 1.1
4     <!DOCTYPE guide SYSTEM "/dtd/guide.dtd">
5    
6     <guide link="/doc/en/gcc-upgrading.xml">
7 vapier 1.19 <title>Gentoo GCC Upgrade Guide</title>
8 jkt 1.1
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 Kundr├ít</mail>
14     </author>
15     <author title="Editor">
16 rane 1.20 <mail link="mark@halcy0n.com">Mark Loeser</mail>
17 jkt 1.1 </author>
18    
19     <abstract>
20     This document will guide the user through the process of upgrading GCC on their
21 vapier 1.19 Gentoo machines.
22 jkt 1.1 </abstract>
23    
24     <!-- The content of this document is licensed under the CC-BY-SA license -->
25     <!-- See http://creativecommons.org/licenses/by-sa/2.5 -->
26     <license/>
27    
28 jkt 1.21 <version>19</version>
29     <date>2006-09-13</date>
30 jkt 1.1
31     <chapter id="intro">
32     <title>Introduction</title>
33     <section>
34     <title>GCC Upgrading</title>
35     <body>
36    
37     <p>
38     Why should you upgrade? Well, GCC is quite similar to any other package on your
39     system, just a bit more critical. You should upgrade GCC whenever a new version
40     fixes some bug that annoys you, new functionality you need is introduced, or if
41     you want to keep your system up-to-date. If none of the previous cases apply to
42     you, you can safely postpone upgrade as long as your GCC version is supported by
43     Gentoo developers.
44     </p>
45    
46     <p>
47 vapier 1.15 If you install a new major version of GCC (such as 3.3.6 to 3.4.5), the system
48     will not switch over to use it automatically. You'll have to explicitly request
49     the change because the migration process might require some additional steps.
50     If you decide not to switch, Portage will continue to use older version of your
51     compiler until you change your mind, or remove the old compiler from the system.
52     Non-major gcc upgrades are switched automatically for you (such as 3.4.5 to
53     3.4.6).
54 jkt 1.1 </p>
55    
56     <p>
57     This guide will document the necessary steps required to perform a seamless
58 neysx 1.6 upgrade of the compiler used by your Gentoo box. A specific section is
59 jkt 1.21 dedicated to the <uri link="#upgrade-3.3-to-3.4">upgrade from GCC 3.3 to 3.4</uri>
60     and issues with <c>libstdc++</c>. A second specific
61 neysx 1.6 section is for users <uri link="#first-install">first installing</uri> Gentoo
62     using a stage3 tarball, after a new GCC major/minor version has been released.
63 jkt 1.1 </p>
64    
65 nightmorph 1.13 <warn>
66     It should be noted that upgrading from GCC-3.4 to GCC-4.1 or greater still
67 jkt 1.18 requires you to follow the <uri link="#upgrade-general">general upgrading
68     instructions</uri>, as GCC-3.4 and GCC-4.1 use slightly different ABIs.
69 nightmorph 1.13 </warn>
70 neysx 1.6
71 jkt 1.1 </body>
72     </section>
73     </chapter>
74    
75     <chapter id="upgrade-general">
76     <title>General Upgrade Instructions</title>
77     <section>
78     <title>Introduction</title>
79     <body>
80    
81     <impo>
82 jkt 1.21 If you're looking for instructions specific to upgrades from GCC-3.3 to GCC-3.4,
83     please consult the <uri link="#upgrade-3.3-to-3.4">dedicated
84 neysx 1.6 section</uri>.
85     </impo>
86    
87     <impo>
88     If you're looking for instructions specific to upgrades in GCC for new
89     installs, please consult the <uri link="#first-install">dedicated
90 jkt 1.1 section</uri>.
91     </impo>
92    
93     <p>
94     Generally speaking, upgrades to <e>bug fix releases</e>, like from 3.3.5 to
95     3.3.6, should be quite safe -- just emerge new version, switch your system to
96     use it and rebuild the only affected package, <c>libtool</c>. However, some GCC
97     upgrades break binary compatibility; in such cases a rebuild of the affected
98     packages (or even whole toolchain and system) might be required.
99     </p>
100    
101     <p>
102     When we spoke about the need to switch your compiler to the newer version by
103     hand, we said it won't happen automatically. However, there is one exception --
104     upgrades to bug fix releases, like from 3.3.5 to 3.3.6 in case you don't use the
105     "multislot" feature allowing them to coexist on one system. Multislot is
106     disabled by default as the majority of users won't benefit from it.
107     </p>
108    
109     <pre caption="Upgrading GCC">
110     # <i>emerge -uav gcc</i>
111    
112 nightmorph 1.14 <comment>(Please substitute "i686-pc-linux-gnu-4.1.1" with the GCC
113 jkt 1.1 version and CHOST settings you've upgraded to:)</comment>
114 nightmorph 1.14 # <i>gcc-config i686-pc-linux-gnu-4.1.1</i>
115 jkt 1.1 # <i>source /etc/profile</i>
116    
117 nightmorph 1.14 <comment>If you upgraded from gcc 3 to 4 (e.g. from 3.4.6 to 4.1.1 in this
118     example) you will have to run fix_libtool_files.sh manually</comment>
119     # <i>fix_libtool_files.sh 3.4.6</i>
120    
121 jkt 1.1 <comment>(Rebuilding libtool)</comment>
122     # <i>emerge --oneshot -av libtool</i>
123     </pre>
124    
125     <p>
126 nightmorph 1.14 To be completely safe that your system is in a sane state, you <e>must</e>
127     rebuild the toolchain and then world to make use of the new compiler.
128 jkt 1.1 </p>
129    
130     <pre caption="Rebuilding system">
131     # <i>emerge -eav system</i>
132     # <i>emerge -eav world</i>
133     </pre>
134    
135     <p>
136 neysx 1.6 It is safe to remove the older GCC version at this time. If you feel the need,
137     please issue the following command (as usual, substitute
138 nightmorph 1.14 <c>=sys-devel/gcc-3.4*</c> with the version you want to uninstall):
139 jkt 1.1 </p>
140    
141     <pre caption="Removing older GCC version">
142 nightmorph 1.14 # <i>emerge -aC =sys-devel/gcc-3.4*</i>
143 jkt 1.1 </pre>
144    
145 jkt 1.18 <impo>
146     Please note that the GCC 4.1 and newer can't compile a 2.4 kernel. Don't remove
147     your old GCC version if you want to use an older kernel.
148     </impo>
149    
150 jkt 1.1 </body>
151     </section>
152     </chapter>
153    
154     <chapter id="upgrade-3.3-to-3.4">
155 jkt 1.21 <title>Upgrading from GCC-3.3 to 3.4</title>
156 jkt 1.1 <section>
157     <title>Introduction</title>
158     <body>
159    
160     <p>
161 jkt 1.21 The upgrade from GCC-3.3 to 3.4 (or greater) is not seamless as the C++ ABI
162 neysx 1.6 changed between these two versions. There is an issue with the <c>libstdc++</c>
163     library which must be taken care of, as well.
164 jkt 1.1 </p>
165    
166     </body>
167     </section>
168     <section id="upgrade-3.3-to-3.4-choices">
169     <title>The Choices</title>
170     <body>
171    
172 jkt 1.5 <impo>
173 jkt 1.18 If you upgrade from gcc 3.4 to 4.1, please consult the <uri
174     link="#upgrade-general">General Update instructions</uri>.
175 nightmorph 1.14 </impo>
176    
177     <impo>
178 jkt 1.5 If you're upgrading on a SPARC machine, you will have to take the way of
179     <uri link="#upgrade-3.3-to-3.4-emerge-e">complete system rebuild</uri> due to
180     some internal <uri link="http://gcc.gnu.org/gcc-3.4/sparc-abi.html">ABI
181     changes</uri> in GCC's parameter passing.
182     </impo>
183    
184 jkt 1.1 <p>
185 nightmorph 1.14 If you upgrade from gcc 3.3 to 3.4, you have two possibilities on how to
186     upgrade your system. The <uri link="#upgrade-3.3-to-3.4-revdep-rebuild">first
187     method</uri> is faster and requires use of the <c>revdep-rebuild</c> tool from
188     package <c>gentoolkit</c> while the <uri
189     link="#upgrade-3.3-to-3.4-emerge-e">second one</uri> rebuilds the entire
190 jkt 1.22 system from scratch so it will make use of new GCC features. It's up to you to
191     decide which of these two ways you will choose. In most cases, the first
192     method is sufficient.
193     </p>
194    
195     <p>
196     If you upgrade from gcc 3.3 to 4.1, do not use the method based on
197 nightmorph 1.14 revdep-rebuild, but do a <uri link="#upgrade-3.3-to-3.4-emerge-e">complete
198     system rebuild</uri>.
199 jkt 1.1 </p>
200    
201     </body>
202     </section>
203     <section id="upgrade-3.3-to-3.4-revdep-rebuild">
204     <title>Using revdep-rebuild</title>
205     <body>
206    
207     <p>
208     This method requires that you first install <c>gentoolkit</c> if you have not
209     already done so. Then we will upgrade GCC and switch to the new compiler. We
210 jkt 1.3 will also rebuild the <c>libtool</c> package to ensure that toolchain is in
211 jkt 1.1 healthy state.
212     </p>
213    
214     <pre caption="Installing gentoolkit and upgrading GCC">
215     # <i>emerge -an gentoolkit</i>
216     # <i>emerge -uav gcc</i>
217 vanquirius 1.11 <comment>(Please substitute "i686-pc-linux-gnu-3.4.5" with the GCC
218     version and CHOST settings you've upgraded to:)</comment>
219     # <i>gcc-config i686-pc-linux-gnu-3.4.5</i>
220 jkt 1.1 # <i>source /etc/profile</i>
221    
222     <comment>(Rebuilding libtool)</comment>
223     # <i>emerge --oneshot -av libtool</i>
224     </pre>
225    
226     <p>
227     Now, we want to see which packages that revdep-rebuild will want to rebuild.
228     Then we will tell revdep-rebuild to actually rebuild the packages. This may take
229     some time, so have some patience.
230     </p>
231    
232     <pre caption="Using revdep-rebuild">
233     # <i>revdep-rebuild --library libstdc++.so.5 -- -p -v</i>
234     # <i>revdep-rebuild --library libstdc++.so.5</i>
235     </pre>
236    
237     <note>
238     It is possible that you might have problems with non-existing package versions
239     due to them being outdated or masked. If this is the case, you will want to use
240     the <c>--package-names</c> option to <c>revdep-rebuild</c>. This causes packages
241     to be recompiled based on the package name, rather than the exact name and
242     version.
243     </note>
244    
245     <p>
246     To provide compatibility with older binary C++ applications and any packages
247     that revdep-rebuild might have missed, <c>sys-libs/libstdc++-v3</c> needs to be
248     merged before you unmerge GCC 3.3 from your system.
249     </p>
250    
251     <pre caption="Installing libstdc++-v3 and cleaning up">
252     # <i>emerge --oneshot sys-libs/libstdc++-v3</i>
253     # <i>emerge -aC =sys-devel/gcc-3.3*</i>
254     </pre>
255    
256     </body>
257     </section>
258     <section id="upgrade-3.3-to-3.4-emerge-e">
259     <title>Using emerge -e</title>
260     <body>
261    
262     <p>
263     This method, while much slower, will rebuild your whole system to ensure that
264     everything has been rebuilt with your new compiler, and therefore safer. At
265     first, you will upgrade GCC and libtool and switch to your new compiler.
266     </p>
267    
268     <pre caption="Upgrading GCC">
269     # <i>emerge -uav gcc</i>
270 vanquirius 1.11 <comment>(Please substitute "i686-pc-linux-gnu-3.4.5" with the GCC
271     version and CHOST settings you've upgraded to:)</comment>
272     # <i>gcc-config i686-pc-linux-gnu-3.4.5</i>
273 jkt 1.1 # <i>source /etc/profile</i>
274    
275 nightmorph 1.14 <comment>If you upgraded from gcc 3 to 4 (e.g. from 3.3.6 to 4.1.1 in this
276     example) you will have to run fix_libtool_files.sh manually</comment>
277     # <i>fix_libtool_files.sh 3.3.6</i>
278    
279 jkt 1.1 <comment>(Rebuilding libtool)</comment>
280     # <i>emerge --oneshot -av libtool</i>
281     </pre>
282    
283     <p>
284     To provide compatibility with older binary C++ applications,
285     <c>sys-libs/libstdc++-v3</c> needs to be merged onto your system.
286     </p>
287    
288     <pre caption="Installing libstdc++-v3">
289     # <i>emerge --oneshot sys-libs/libstdc++-v3</i>
290     </pre>
291    
292     <p>
293     Now we will go about first rebuilding the system target, then the world target.
294     This will take a very long time, depending on the number of packages that you
295     have installed, as it will rebuild your entire toolchain and supporting system
296     files, followed by every package on your system, including the toolchain. This
297     is necessary to ensure that all packages have been compiled with the new
298     toolchain, including the toolchain itself.
299     </p>
300    
301     <pre caption="Rebuilding system and world">
302     # <i>emerge -e system</i>
303     # <i>emerge -e world</i>
304     </pre>
305    
306     <p>
307     It is also safe to remove older GCC versions at this time:
308     </p>
309    
310     <pre caption="Cleaning up">
311     # <i>emerge -aC =sys-devel/gcc-3.3*</i>
312     </pre>
313    
314     </body>
315     </section>
316     </chapter>
317    
318 neysx 1.6 <chapter id="first-install">
319     <title>Upgrading to GCC on a First Install</title>
320     <section>
321     <title>Introduction</title>
322     <body>
323    
324     <p>
325     A GCC upgrade on a system after installation from a stage3 tarball is a simple
326     affair. One advantage users of new installations have is they do not have a
327     plethora of software installed that links against the older version of GCC.
328 jkt 1.21 The following example is for a GCC-3.3 to 3.4 upgrade. Certain parts
329 neysx 1.6 will be different if upgrading from other versions of GCC. For example, the
330     library names used for <c>revdep-rebuild</c> below are GCC 3.3 specific, as
331     well as the need to install <c>libstdc++-v3</c>.
332     </p>
333    
334     <p>
335     If a user has not made any customizations to their system yet, then there are
336     very few steps to get their system upgraded to a new GCC version. As with the
337     GCC-3.3 to 3.4 upgrade, the user has a couple options. However, unlike the
338     GCC-3.3 to 3.4 upgrade, this one is less complicated as there are fewer
339     differences between the methods. The <uri
340     link="#first-install-revdep-rebuild">first method</uri> is faster and makes use
341     of the <c>revdep-rebuild</c> tool from <c>gentoolkit</c>, similar to the above
342     procedure. Using revdep-rebuild causes only packages which actually link
343     against GCC libraries to be rebuilt, while the <uri
344     link="#first-install-emerge-e">second method</uri> causes your entire new
345     install to be recompiled with the new GCC version and takes much longer. This
346     second method is never required and only documented for completeness.
347     </p>
348    
349     <p>
350     These first steps are common between both methods, and should be completed by
351     everyone.
352     </p>
353    
354     <pre caption="Upgrading GCC">
355     # <i>emerge -uav gcc</i>
356 vanquirius 1.11 <comment>(Please substitute "i686-pc-linux-gnu-3.4.5" with the GCC
357     version and CHOST settings you've upgraded to:)</comment>
358     # <i>gcc-config i686-pc-linux-gnu-3.4.5</i>
359 neysx 1.6 # <i>source /etc/profile</i>
360    
361     <comment>(Rebuilding libtool)</comment>
362     # <i>emerge --oneshot -av libtool</i>
363     </pre>
364    
365     <p>
366     To provide compatibility with older binary C++ applications,
367     <c>sys-libs/libstdc++-v3</c> needs to be merged onto your system.
368     </p>
369    
370     <pre caption="Installing libstdc++-v3">
371     # <i>emerge --oneshot sys-libs/libstdc++-v3</i>
372     </pre>
373    
374     </body>
375     </section>
376    
377     <section id="first-install-revdep-rebuild">
378     <title>Using revdep-rebuild</title>
379     <body>
380    
381     <p>
382     This method requires that you first install <c>gentoolkit</c> if you have not
383     already done so. We will then run <c>revdep-rebuild</c> to actually scan the
384     installed packages for ones we need to rebuild, then rebuild them.
385     </p>
386    
387     <pre caption="Installing gentoolkit and running revdep-rebuild">
388     # <i>emerge -an gentoolkit</i>
389     # <i>revdep-rebuild --library libstdc++.so.5 -- -p -v</i>
390     # <i>revdep-rebuild --library libstdc++.so.5</i>
391     </pre>
392    
393     <note>
394     It is possible that you might have problems with non-existing package versions
395     due to them being outdated or masked. If this is the case, you will want to use
396     the <c>--package-names</c> option to <c>revdep-rebuild</c>. This causes packages
397     to be recompiled based on the package name, rather than the exact name and
398     version.
399     </note>
400    
401     </body>
402     </section>
403     <section id="first-install-emerge-e">
404     <title>Using emerge -e</title>
405     <body>
406    
407     <p>
408     This method, while much slower, will rebuild the system target to ensure that
409     everything has been rebuilt with your new compiler. This is not necessary, but
410     is valid if you are also making changes to CFLAGS or other make.conf variables
411     that will affect the system compile.
412     </p>
413    
414     <p>
415     Since we are performing these actions after an initial installation, we do not
416 jkt 1.10 need to recompile the <c>world</c> target as we would when doing an upgrade on
417     an already installed system. However, you may choose to perform a world update
418     in place of the system update, to ensure that all packages are updated.
419 neysx 1.6 </p>
420    
421     <pre caption="Rebuilding system">
422     # <i>emerge -e system</i>
423     </pre>
424    
425 jkt 1.10 </body>
426     </section>
427     <section id="first-install-cleaning-up">
428     <title>Cleaning up</title>
429     <body>
430    
431 neysx 1.6 <p>
432 jkt 1.7 It is also safe to remove older GCC versions at this time. Please substitute
433     <c>YOUR-NEW-GCC-VERSION</c> with the actual version you've upgraded to:
434 neysx 1.6 </p>
435    
436     <pre caption="Cleaning up">
437 jkt 1.7 # <i>emerge -aC "&lt;sys-devel/gcc-YOUR-NEW-GCC-VERSION"</i>
438 neysx 1.6 </pre>
439    
440     </body>
441     </section>
442 jkt 1.1 </chapter>
443 jkt 1.8
444     <chapter id="common-pitfalls">
445     <title>Common Pitfalls</title>
446     <section>
447     <body>
448    
449     <p>
450     It's important to disable <c>distcc</c> during upgrade. Mixing compiler versions
451     on your nodes <e>will</e> cause build issues. This is not required for ccache,
452     as the cache objects will be invalidated anyway.
453     </p>
454    
455     <p>
456     Always use same GCC version for your kernel and additional kernel modules. Once
457     you rebuild your world with new GCC, external modules (like
458 nightmorph 1.14 <c>app-emulation/qemu-softmmu</c>) will fail to load. Please rebuild your
459     kernel with the new GCC to fix that.
460 jkt 1.8 </p>
461    
462 jkt 1.9 <p>
463     If you're upgrading on a SPARC machine, make sure to rerun <c>silo -f</c> after
464     re-emerging world to avoid possible issues.
465     </p>
466    
467 jkt 1.8 </body>
468     </section>
469     <section>
470     <title>Frequent Error Messages</title>
471     <body>
472    
473     <p>
474     If your system complains about something like <e>libtool: link:
475     `/usr/lib/gcc-lib/i686-pc-linux-gnu/3.3.6/libstdc++.la' is not a valid libtool
476     archive</e>, please run <c>/sbin/fix_libtool_files.sh 3.3.6</c> (substitute
477     "3.3.6" with the version numbers from the error message).
478     </p>
479    
480     <p>
481 nightmorph 1.14 If you see <e>error: /usr/bin/gcc-config: line 632:
482 jkt 1.8 /etc/env.d/gcc/i686-pc-linux-gnu-3.3.5: No such file or directory</e>, then try
483     deleting <path>/etc/env.d/gcc/config-i686-pc-linux-gnu</path> and running
484 nightmorph 1.14 <c>gcc-config</c> again, followed by <c>source /etc/profile</c>. Only do this
485     if you do not have any cross-compilers set up, though.
486 jkt 1.8 </p>
487    
488     <p>
489     If a package fails during <c>emerge -e system</c> or <c>emerge -e world</c>,
490     you can resume operation with <c>emerge --resume</c>. If a package fails
491     repeatedly, skip it with <c>emerge --resume --skipfirst</c>. Don't run any
492     other instances of emerge in between or you will lose the resume information.
493     </p>
494    
495     <p>
496     If you get an error message <e>spec failure: unrecognized spec option</e> while
497     upgrading your compiler, try to switch back to your default compiler, unset the
498     <c>GCC_SPECS</c> variable and upgrade GCC again:
499     </p>
500    
501     <pre caption="Restoring primary specs">
502     # <i>gcc-config 1</i>
503     # <i>source /etc/profile</i>
504     # <i>unset GCC_SPECS</i>
505     # <i>emerge -uav gcc</i>
506     </pre>
507    
508     </body>
509     </section>
510     </chapter>
511 jkt 1.1 </guide>

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