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3.4.4->3.4.5, add "(Please substitute "i686-pc-linux-gnu-3.4.5" with the GCC
 version and CHOST settings you've upgraded to:)" to all codelists that
have gcc-config in them. Reported by Justin R Eylander
<jeylande at cs dot indiana dot edu> via e-mail.

1 jkt 1.1 <?xml version='1.0' encoding="UTF-8"?>
2 vanquirius 1.11 <!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/gcc-upgrading.xml,v 1.10 2006/02/25 09:37:33 jkt Exp $ -->
3 jkt 1.1
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 Kundr├ít</mail>
14     </author>
15     <author title="Editor">
16     <mail link="halcy0n@gentoo.org">Mark Loeser</mail>
17     </author>
18    
19     <abstract>
20     This document will guide the user through the process of upgrading GCC on their
21     Gentoo Linux machines.
22     </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 vanquirius 1.11 <version>10</version>
29     <date>2006-02-28</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     If you install a newer version of GCC, the system will not switch over to use it
48     automatically. You'll have to explicitly request the change because the
49     migration process might require some additional steps. If you decide not to
50     switch, Portage will continue to use older version of your compiler until you
51     change your mind, or remove the old compiler from the system.
52     </p>
53    
54     <p>
55     This guide will document the necessary steps required to perform a seamless
56 neysx 1.6 upgrade of the compiler used by your Gentoo box. A specific section is
57     dedicated to the <uri link="#upgrade-3.3-to-3.4">upgrade from GCC 3.3 to 3.4 or
58     greater versions</uri> and issues with <c>libstdc++</c>. A second specific
59     section is for users <uri link="#first-install">first installing</uri> Gentoo
60     using a stage3 tarball, after a new GCC major/minor version has been released.
61 jkt 1.1 </p>
62    
63 neysx 1.6 <note>
64     It should be noted that upgrading from GCC-3.4 to GCC-4.0 or greater requires
65     no real changes to be made by the user, as GCC-3.4 and GCC-4.0 use the same
66     ABI. All that is required is that <c>gcc-config</c> is used to select the
67     compiler desired.
68     </note>
69    
70 jkt 1.1 </body>
71     </section>
72     </chapter>
73    
74     <chapter id="upgrade-general">
75     <title>General Upgrade Instructions</title>
76     <section>
77     <title>Introduction</title>
78     <body>
79    
80     <impo>
81 neysx 1.6 If you're looking for instructions specific to upgrades from GCC-3.3 to GCC-3.4
82     or greater, please consult the <uri link="#upgrade-3.3-to-3.4">dedicated
83     section</uri>.
84     </impo>
85    
86     <impo>
87     If you're looking for instructions specific to upgrades in GCC for new
88     installs, please consult the <uri link="#first-install">dedicated
89 jkt 1.1 section</uri>.
90     </impo>
91    
92     <p>
93     Generally speaking, upgrades to <e>bug fix releases</e>, like from 3.3.5 to
94     3.3.6, should be quite safe -- just emerge new version, switch your system to
95     use it and rebuild the only affected package, <c>libtool</c>. However, some GCC
96     upgrades break binary compatibility; in such cases a rebuild of the affected
97     packages (or even whole toolchain and system) might be required.
98     </p>
99    
100     <p>
101     When we spoke about the need to switch your compiler to the newer version by
102     hand, we said it won't happen automatically. However, there is one exception --
103     upgrades to bug fix releases, like from 3.3.5 to 3.3.6 in case you don't use the
104     "multislot" feature allowing them to coexist on one system. Multislot is
105     disabled by default as the majority of users won't benefit from it.
106     </p>
107    
108     <pre caption="Upgrading GCC">
109     # <i>emerge -uav gcc</i>
110    
111 vanquirius 1.11 <comment>(Please substitute "i686-pc-linux-gnu-3.4.5" with the GCC
112 jkt 1.1 version and CHOST settings you've upgraded to:)</comment>
113 vanquirius 1.11 # <i>gcc-config i686-pc-linux-gnu-3.4.5</i>
114 jkt 1.1 # <i>source /etc/profile</i>
115    
116     <comment>(Rebuilding libtool)</comment>
117     # <i>emerge --oneshot -av libtool</i>
118     </pre>
119    
120     <p>
121     Now let's rebuild toolchain and then world so we will make use of the new
122     compiler.
123     </p>
124    
125     <pre caption="Rebuilding system">
126     # <i>emerge -eav system</i>
127     # <i>emerge -eav world</i>
128     </pre>
129    
130     <p>
131 neysx 1.6 It is safe to remove the older GCC version at this time. If you feel the need,
132     please issue the following command (as usual, substitute
133 jkt 1.1 <c>=sys-devel/gcc-3.3*</c> with the version you want to uninstall):
134     </p>
135    
136     <pre caption="Removing older GCC version">
137     # <i>emerge -aC =sys-devel/gcc-3.3*</i>
138     </pre>
139    
140     </body>
141     </section>
142     </chapter>
143    
144     <chapter id="upgrade-3.3-to-3.4">
145 neysx 1.6 <title>Upgrading from GCC-3.3 to 3.4 or greater</title>
146 jkt 1.1 <section>
147     <title>Introduction</title>
148     <body>
149    
150     <p>
151 neysx 1.6 The upgrade from GCC-3.3 to 3.4 or greater is not seamless as the C++ ABI
152     changed between these two versions. There is an issue with the <c>libstdc++</c>
153     library which must be taken care of, as well.
154 jkt 1.1 </p>
155    
156     </body>
157     </section>
158     <section id="upgrade-3.3-to-3.4-choices">
159     <title>The Choices</title>
160     <body>
161    
162 jkt 1.5 <impo>
163     If you're upgrading on a SPARC machine, you will have to take the way of
164     <uri link="#upgrade-3.3-to-3.4-emerge-e">complete system rebuild</uri> due to
165     some internal <uri link="http://gcc.gnu.org/gcc-3.4/sparc-abi.html">ABI
166     changes</uri> in GCC's parameter passing.
167     </impo>
168    
169 jkt 1.1 <p>
170 neysx 1.6 You have two possibilities on how to upgrade your system. The <uri
171     link="#upgrade-3.3-to-3.4-revdep-rebuild">first method</uri> is faster and
172     requires use of the <c>revdep-rebuild</c> tool from package <c>gentoolkit</c>
173     while the <uri link="#upgrade-3.3-to-3.4-emerge-e">second one</uri> rebuilds the
174 jkt 1.1 entire system from scratch so it will make use of new GCC features. It's up to
175 neysx 1.6 you to decide which of these two ways you will choose. In most cases, the first
176     method is sufficient.
177 jkt 1.1 </p>
178    
179     </body>
180     </section>
181     <section id="upgrade-3.3-to-3.4-revdep-rebuild">
182     <title>Using revdep-rebuild</title>
183     <body>
184    
185     <p>
186     This method requires that you first install <c>gentoolkit</c> if you have not
187     already done so. Then we will upgrade GCC and switch to the new compiler. We
188 jkt 1.3 will also rebuild the <c>libtool</c> package to ensure that toolchain is in
189 jkt 1.1 healthy state.
190     </p>
191    
192     <pre caption="Installing gentoolkit and upgrading GCC">
193     # <i>emerge -an gentoolkit</i>
194     # <i>emerge -uav gcc</i>
195 vanquirius 1.11 <comment>(Please substitute "i686-pc-linux-gnu-3.4.5" with the GCC
196     version and CHOST settings you've upgraded to:)</comment>
197     # <i>gcc-config i686-pc-linux-gnu-3.4.5</i>
198 jkt 1.1 # <i>source /etc/profile</i>
199    
200     <comment>(Rebuilding libtool)</comment>
201     # <i>emerge --oneshot -av libtool</i>
202     </pre>
203    
204     <note>
205     This assumes that you have <c>CHOST="i686-pc-linux-gnu"</c> set. If you are
206     using another CHOST, please use the appropriate gcc-config line.
207     </note>
208    
209     <p>
210     Now, we want to see which packages that revdep-rebuild will want to rebuild.
211     Then we will tell revdep-rebuild to actually rebuild the packages. This may take
212     some time, so have some patience.
213     </p>
214    
215     <pre caption="Using revdep-rebuild">
216     # <i>revdep-rebuild --library libstdc++.so.5 -- -p -v</i>
217     # <i>revdep-rebuild --library libstdc++.so.5</i>
218     </pre>
219    
220     <note>
221     It is possible that you might have problems with non-existing package versions
222     due to them being outdated or masked. If this is the case, you will want to use
223     the <c>--package-names</c> option to <c>revdep-rebuild</c>. This causes packages
224     to be recompiled based on the package name, rather than the exact name and
225     version.
226     </note>
227    
228     <p>
229     To provide compatibility with older binary C++ applications and any packages
230     that revdep-rebuild might have missed, <c>sys-libs/libstdc++-v3</c> needs to be
231     merged before you unmerge GCC 3.3 from your system.
232     </p>
233    
234     <pre caption="Installing libstdc++-v3 and cleaning up">
235     # <i>emerge --oneshot sys-libs/libstdc++-v3</i>
236     # <i>emerge -aC =sys-devel/gcc-3.3*</i>
237     </pre>
238    
239     </body>
240     </section>
241     <section id="upgrade-3.3-to-3.4-emerge-e">
242     <title>Using emerge -e</title>
243     <body>
244    
245     <p>
246     This method, while much slower, will rebuild your whole system to ensure that
247     everything has been rebuilt with your new compiler, and therefore safer. At
248     first, you will upgrade GCC and libtool and switch to your new compiler.
249     </p>
250    
251     <pre caption="Upgrading GCC">
252     # <i>emerge -uav gcc</i>
253 vanquirius 1.11 <comment>(Please substitute "i686-pc-linux-gnu-3.4.5" with the GCC
254     version and CHOST settings you've upgraded to:)</comment>
255     # <i>gcc-config i686-pc-linux-gnu-3.4.5</i>
256 jkt 1.1 # <i>source /etc/profile</i>
257    
258     <comment>(Rebuilding libtool)</comment>
259     # <i>emerge --oneshot -av libtool</i>
260     </pre>
261    
262     <note>
263     This assumes that you have <c>CHOST="i686-pc-linux-gnu"</c> set. If you are
264     using another CHOST, please use the appropriate gcc-config line.
265     </note>
266    
267     <p>
268     To provide compatibility with older binary C++ applications,
269     <c>sys-libs/libstdc++-v3</c> needs to be merged onto your system.
270     </p>
271    
272     <pre caption="Installing libstdc++-v3">
273     # <i>emerge --oneshot sys-libs/libstdc++-v3</i>
274     </pre>
275    
276     <p>
277     Now we will go about first rebuilding the system target, then the world target.
278     This will take a very long time, depending on the number of packages that you
279     have installed, as it will rebuild your entire toolchain and supporting system
280     files, followed by every package on your system, including the toolchain. This
281     is necessary to ensure that all packages have been compiled with the new
282     toolchain, including the toolchain itself.
283     </p>
284    
285     <pre caption="Rebuilding system and world">
286     # <i>emerge -e system</i>
287     # <i>emerge -e world</i>
288     </pre>
289    
290     <p>
291     It is also safe to remove older GCC versions at this time:
292     </p>
293    
294     <pre caption="Cleaning up">
295     # <i>emerge -aC =sys-devel/gcc-3.3*</i>
296     </pre>
297    
298     </body>
299     </section>
300     </chapter>
301    
302 neysx 1.6 <chapter id="first-install">
303     <title>Upgrading to GCC on a First Install</title>
304     <section>
305     <title>Introduction</title>
306     <body>
307    
308     <p>
309     A GCC upgrade on a system after installation from a stage3 tarball is a simple
310     affair. One advantage users of new installations have is they do not have a
311     plethora of software installed that links against the older version of GCC.
312     The following example is for a GCC-3.3 to 3.4 or greater upgrade. Certain parts
313     will be different if upgrading from other versions of GCC. For example, the
314     library names used for <c>revdep-rebuild</c> below are GCC 3.3 specific, as
315     well as the need to install <c>libstdc++-v3</c>.
316     </p>
317    
318     <p>
319     If a user has not made any customizations to their system yet, then there are
320     very few steps to get their system upgraded to a new GCC version. As with the
321     GCC-3.3 to 3.4 upgrade, the user has a couple options. However, unlike the
322     GCC-3.3 to 3.4 upgrade, this one is less complicated as there are fewer
323     differences between the methods. The <uri
324     link="#first-install-revdep-rebuild">first method</uri> is faster and makes use
325     of the <c>revdep-rebuild</c> tool from <c>gentoolkit</c>, similar to the above
326     procedure. Using revdep-rebuild causes only packages which actually link
327     against GCC libraries to be rebuilt, while the <uri
328     link="#first-install-emerge-e">second method</uri> causes your entire new
329     install to be recompiled with the new GCC version and takes much longer. This
330     second method is never required and only documented for completeness.
331     </p>
332    
333     <p>
334     These first steps are common between both methods, and should be completed by
335     everyone.
336     </p>
337    
338     <pre caption="Upgrading GCC">
339     # <i>emerge -uav gcc</i>
340 vanquirius 1.11 <comment>(Please substitute "i686-pc-linux-gnu-3.4.5" with the GCC
341     version and CHOST settings you've upgraded to:)</comment>
342     # <i>gcc-config i686-pc-linux-gnu-3.4.5</i>
343 neysx 1.6 # <i>source /etc/profile</i>
344    
345     <comment>(Rebuilding libtool)</comment>
346     # <i>emerge --oneshot -av libtool</i>
347     </pre>
348    
349     <note>
350     This assumes that you have <c>CHOST="i686-pc-linux-gnu"</c> set. If you are
351     using another CHOST, please use the appropriate gcc-config line.
352     </note>
353    
354     <p>
355     To provide compatibility with older binary C++ applications,
356     <c>sys-libs/libstdc++-v3</c> needs to be merged onto your system.
357     </p>
358    
359     <pre caption="Installing libstdc++-v3">
360     # <i>emerge --oneshot sys-libs/libstdc++-v3</i>
361     </pre>
362    
363     </body>
364     </section>
365    
366     <section id="first-install-revdep-rebuild">
367     <title>Using revdep-rebuild</title>
368     <body>
369    
370     <p>
371     This method requires that you first install <c>gentoolkit</c> if you have not
372     already done so. We will then run <c>revdep-rebuild</c> to actually scan the
373     installed packages for ones we need to rebuild, then rebuild them.
374     </p>
375    
376     <pre caption="Installing gentoolkit and running revdep-rebuild">
377     # <i>emerge -an gentoolkit</i>
378     # <i>revdep-rebuild --library libstdc++.so.5 -- -p -v</i>
379     # <i>revdep-rebuild --library libstdc++.so.5</i>
380     </pre>
381    
382     <note>
383     It is possible that you might have problems with non-existing package versions
384     due to them being outdated or masked. If this is the case, you will want to use
385     the <c>--package-names</c> option to <c>revdep-rebuild</c>. This causes packages
386     to be recompiled based on the package name, rather than the exact name and
387     version.
388     </note>
389    
390     </body>
391     </section>
392     <section id="first-install-emerge-e">
393     <title>Using emerge -e</title>
394     <body>
395    
396     <p>
397     This method, while much slower, will rebuild the system target to ensure that
398     everything has been rebuilt with your new compiler. This is not necessary, but
399     is valid if you are also making changes to CFLAGS or other make.conf variables
400     that will affect the system compile.
401     </p>
402    
403     <p>
404     Since we are performing these actions after an initial installation, we do not
405 jkt 1.10 need to recompile the <c>world</c> target as we would when doing an upgrade on
406     an already installed system. However, you may choose to perform a world update
407     in place of the system update, to ensure that all packages are updated.
408 neysx 1.6 </p>
409    
410     <pre caption="Rebuilding system">
411     # <i>emerge -e system</i>
412     </pre>
413    
414 jkt 1.10 </body>
415     </section>
416     <section id="first-install-cleaning-up">
417     <title>Cleaning up</title>
418     <body>
419    
420 neysx 1.6 <p>
421 jkt 1.7 It is also safe to remove older GCC versions at this time. Please substitute
422     <c>YOUR-NEW-GCC-VERSION</c> with the actual version you've upgraded to:
423 neysx 1.6 </p>
424    
425     <pre caption="Cleaning up">
426 jkt 1.7 # <i>emerge -aC "&lt;sys-devel/gcc-YOUR-NEW-GCC-VERSION"</i>
427 neysx 1.6 </pre>
428    
429     </body>
430     </section>
431 jkt 1.1 </chapter>
432 jkt 1.8
433     <chapter id="common-pitfalls">
434     <title>Common Pitfalls</title>
435     <section>
436     <body>
437    
438     <p>
439     It's important to disable <c>distcc</c> during upgrade. Mixing compiler versions
440     on your nodes <e>will</e> cause build issues. This is not required for ccache,
441     as the cache objects will be invalidated anyway.
442     </p>
443    
444     <p>
445     Always use same GCC version for your kernel and additional kernel modules. Once
446     you rebuild your world with new GCC, external modules (like
447     <c>app-emulation/qemu-softmmu</c>) will fail to load. Please rebuild your kernel
448     with new GCC to fix that.
449     </p>
450    
451 jkt 1.9 <p>
452     If you're upgrading on a SPARC machine, make sure to rerun <c>silo -f</c> after
453     re-emerging world to avoid possible issues.
454     </p>
455    
456 jkt 1.8 </body>
457     </section>
458     <section>
459     <title>Frequent Error Messages</title>
460     <body>
461    
462     <p>
463     If your system complains about something like <e>libtool: link:
464     `/usr/lib/gcc-lib/i686-pc-linux-gnu/3.3.6/libstdc++.la' is not a valid libtool
465     archive</e>, please run <c>/sbin/fix_libtool_files.sh 3.3.6</c> (substitute
466     "3.3.6" with the version numbers from the error message).
467     </p>
468    
469     <p>
470     If you see the <e>error: /usr/bin/gcc-config: line 632:
471     /etc/env.d/gcc/i686-pc-linux-gnu-3.3.5: No such file or directory</e>, then try
472     deleting <path>/etc/env.d/gcc/config-i686-pc-linux-gnu</path> and running
473     <c>gcc-config</c> again, followed by <c>source /etc/profile</c>. Only do this if
474     you do not have any cross-compilers set up, though.
475     </p>
476    
477     <p>
478     If a package fails during <c>emerge -e system</c> or <c>emerge -e world</c>,
479     you can resume operation with <c>emerge --resume</c>. If a package fails
480     repeatedly, skip it with <c>emerge --resume --skipfirst</c>. Don't run any
481     other instances of emerge in between or you will lose the resume information.
482     </p>
483    
484     <p>
485     If you get an error message <e>spec failure: unrecognized spec option</e> while
486     upgrading your compiler, try to switch back to your default compiler, unset the
487     <c>GCC_SPECS</c> variable and upgrade GCC again:
488     </p>
489    
490     <pre caption="Restoring primary specs">
491     # <i>gcc-config 1</i>
492     # <i>source /etc/profile</i>
493     # <i>unset GCC_SPECS</i>
494     # <i>emerge -uav gcc</i>
495     </pre>
496    
497     </body>
498     </section>
499     </chapter>
500 jkt 1.1 </guide>

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