/[gentoo]/xml/htdocs/doc/en/kernel-upgrade.xml
Gentoo

Contents of /xml/htdocs/doc/en/kernel-upgrade.xml

Parent Directory Parent Directory | Revision Log Revision Log


Revision 1.14 - (hide annotations) (download) (as text)
Wed Feb 22 20:30:20 2006 UTC (8 years, 6 months ago) by nightmorph
Branch: MAIN
Changes since 1.13: +10 -15 lines
File MIME type: application/xml
Fixed module-rebuild section for bug 119235

1 swift 1.1 <?xml version="1.0" encoding="UTF-8"?>
2 nightmorph 1.14 <!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/kernel-upgrade.xml,v 1.13 2006/01/08 15:16:15 neysx Exp $ -->
3 swift 1.1
4     <!DOCTYPE guide SYSTEM "/dtd/guide.dtd">
5 neysx 1.3 <guide link="/doc/en/kernel-upgrade.xml">
6 swift 1.1 <title>Gentoo Linux Kernel Upgrade Guide</title>
7     <author title="Author">
8 neysx 1.12 <mail link="dsd@gentoo.org">Daniel Drake</mail>
9 swift 1.1 </author>
10    
11     <abstract>
12     This document describes the process of upgrading your kernel from one release
13     to another.
14     </abstract>
15    
16     <!-- The content of this document is licensed under the CC-BY-SA license -->
17 jkt 1.9 <!-- See http://creativecommons.org/licenses/by-sa/2.5 -->
18 swift 1.1 <license/>
19    
20 nightmorph 1.14 <version>0.3</version>
21     <date>2006-02-22</date>
22 swift 1.1
23     <chapter>
24     <title>Introduction</title>
25     <section>
26     <body>
27    
28     <p>
29     The kernel is one of the few package classes in portage that requires some
30     manual intervention to complete the upgrade. Portage will download and
31     install the kernel source for you, but then it is up to you to step in and
32     compile the new kernel before any changes will take effect.
33     </p>
34    
35     <p>
36 swift 1.4 Although this guide is targeted at users upgrading from one kernel release
37 swift 1.1 to another, it will also be useful for users migrating from one kernel
38     package to another.
39     </p>
40    
41     <p>
42 neysx 1.3 <c>gentoo-sources</c> is used as an example in this document, however, the
43 swift 1.1 instructions here also apply to the other packages present in our tree.
44     </p>
45    
46     </body>
47     </section>
48     </chapter>
49    
50     <chapter>
51 swift 1.4 <title>Why upgrade the kernel?</title>
52 swift 1.1 <section>
53     <body>
54    
55     <p>
56     Generally, upgrading from one minor kernel release to the next won't bring any
57 swift 1.4 major differences. There are several reasons to upgrade the kernel. One is to
58     take advantage of a specific new feature or driver; another is to be protected
59     against a security vulnerability, or just to maintain an up-to-date and healthy
60     system.
61 swift 1.1 </p>
62    
63     <p>
64     Even if you choose not to update to every new kernel revision, it is
65     recommended that you at least upgrade from time to time. It is strongly
66     recommended that you immediately upgrade to a new kernel if that new release
67     solves a security problem.
68     </p>
69    
70     </body>
71     </section>
72     </chapter>
73    
74     <chapter>
75     <title>Obtaining the newer sources through Portage</title>
76     <section>
77     <body>
78    
79     <p>
80     You upgrade the kernel sources like you would upgrade any other package -
81     using the <c>emerge</c> utility. It will probably be the case that you want to
82     upgrade your kernel when you see the upgrade appearing on your world updates
83     list. For example:
84     </p>
85    
86     <pre caption="New kernel sources appearing on update list">
87     # <i>emerge -Dup world</i>
88     Calculating dependencies ...done!
89 neysx 1.3 [ebuild NS ] sys-kernel/gentoo-sources-2.6.9-r2 [2.6.8-r5]
90 swift 1.1 </pre>
91    
92 neysx 1.3 <note>
93     The "NS" label in the above output means that the new kernel will be installed
94     in a New Slot, i.e. the sources of your old kernel will be kept around, until
95     you manually remove them.
96     </note>
97    
98 swift 1.1 <p>
99     You can then go ahead and install the update, e.g.:
100     </p>
101    
102     <pre caption="Upgrading your kernel sources">
103 neysx 1.3 # <i>emerge -u gentoo-sources</i>
104 swift 1.1 </pre>
105    
106     <p>
107     The kernel sources will then be installed into a subdirectory of
108 swift 1.4 <path>/usr/src</path>. In the above example, the new kernel sources will be
109 swift 1.1 installed at <path>/usr/src/linux-2.6.9-gentoo-r2</path>.
110     </p>
111    
112     </body>
113     </section>
114     </chapter>
115    
116     <chapter>
117     <title>Updating the /usr/src/linux symbolic link</title>
118     <section>
119     <body>
120    
121     <p>
122 neysx 1.8 Gentoo requires that the <path>/usr/src/linux</path> symbolic link points to
123     the sources of the kernel you are running.
124 swift 1.1 </p>
125    
126     <p>
127 neysx 1.8 Portage can update the symlink automatically when you emerge new kernel
128     sources. All you have to do is add the <c>symlink</c> flag to the USE variable
129     in <path>/etc/make.conf</path>.
130 swift 1.1 </p>
131    
132 neysx 1.8 <pre caption="Example of USE variable in /etc/make.conf">
133     <comment>(Add the symlink keyword)</comment>
134     USE="<i>symlink</i> x86 3dnow 3dnowex X aac aalib adns alsa apache2"
135     </pre>
136    
137     <p>
138     If you really want to do it yourself, the following example shows you how to
139     make the link point to <path>linux-2.6.9-gentoo-r2</path>:
140     </p>
141    
142     <pre caption="Updating the /usr/src/linux softlink manually">
143 swift 1.1 # <i>cd /usr/src</i>
144 swift 1.2 # <i>ln -sfn linux-2.6.9-gentoo-r2 linux</i>
145 swift 1.1 </pre>
146    
147     </body>
148     </section>
149     </chapter>
150    
151     <chapter id="install">
152     <title>Configuring, compiling and installing the new kernel</title>
153     <section>
154     <body>
155    
156     <p>
157     For either of these options, you should refer to the instructions given in the
158 swift 1.6 <uri link="/doc/en/handbook/index.xml">Gentoo
159 swift 1.1 Handbook</uri> relating to <e>Configuring the Kernel</e> and <e>Configuring
160 swift 1.4 the Bootloader</e>. Below is an outline of the required actions:
161 swift 1.1 </p>
162    
163     </body>
164     </section>
165     <section>
166     <title>Option 1: Automatic kernel setup with Genkernel</title>
167     <body>
168    
169     <p>
170     If you are a genkernel user, you just need to repeat the stages you went
171     through when installing your kernel for the first time.
172     </p>
173    
174     <p>
175     Simply run genkernel in the normal way:
176     </p>
177    
178     <pre caption="Invoking genkernel">
179 swift 1.7 <comment>(For 2.4 kernels:)</comment>
180 swift 1.1 # <i>genkernel all</i>
181 swift 1.7
182     <comment>(For 2.6 kernels:)</comment>
183     # <i>genkernel --udev all</i>
184 swift 1.1 </pre>
185    
186     <p>
187     You can also use extra parameters for other genkernel functionality. For
188     example, if you wish to configure some extra kernel options using
189     <c>menuconfig</c> and you wish genkernel to automatically update your grub
190 swift 1.5 boot loader configuration, then invoke genkernel as follows:
191 swift 1.1 </p>
192    
193     <pre caption="Invoking genkernel with some common arguments">
194     # <i>genkernel --menuconfig --bootloader=grub all</i>
195     </pre>
196    
197     <p>
198     For more info, follow the
199 swift 1.6 <uri link="/doc/en/genkernel.xml">Gentoo Linux Genkernel
200 swift 1.4 Guide</uri>, or refer to the <uri link="/doc/en/handbook/index.xml">Gentoo
201     Handbook</uri>. Many of the options can be set in the configuration file for
202 swift 1.6 <c>genkernel</c>, <path>/etc/genkernel.conf</path>.
203 swift 1.1 </p>
204    
205     </body>
206     </section>
207     <section>
208     <title>Option 2: Manual configuration</title>
209     <body>
210    
211     <p>
212     To begin, open the <c>menuconfig</c> utility in the kernel source tree:
213     </p>
214    
215     <pre caption="Invoking menuconfig">
216     # <i>cd /usr/src/linux</i>
217     # <i>make menuconfig</i>
218     </pre>
219    
220     <p>
221 swift 1.4 Select the options required for your hardware and operating environment. For
222     additional information on kernel configuration, refer to the chapter entitled
223     <e>Configuring the Kernel</e> of the <uri
224     link="/doc/en/handbook/index.xml">Gentoo Handbook</uri>.
225 swift 1.1 </p>
226    
227     <p>
228     Next, compile your kernel and copy it over to your boot partition. Again,
229 swift 1.4 follow the <uri link="/doc/en/handbook/index.xml">Gentoo Handbook</uri>
230     instructions outlined in the chapter on <e>Configuring the Bootloader</e>. If
231     <path>/boot</path> is a separate partition, ensure it is mounted before copying
232     the compiled kernel to this directory! Failing to do so would keep you from
233     booting the system with your new kernel.
234 swift 1.1 </p>
235    
236     <pre caption="Compiling and installing the new kernel">
237     # <i>make &amp;&amp; make modules_install</i>
238     # <i>mount /boot</i>
239     # <i>cp arch/i386/boot/bzImage /boot/bzImage-2.6.9-gentoo-r2</i>
240     </pre>
241    
242     <p>
243 swift 1.5 Finally, you should update your boot loader configuration, adding an entry for
244     the new kernel (don't delete the old one just yet!) and unmount the
245 swift 1.4 <path>/boot</path> partition. Again, refer to the
246     <uri link="/doc/en/handbook/index.xml">Gentoo Handbook</uri>
247     for detailed instructions on this procedure.
248 swift 1.1 </p>
249    
250     </body>
251     </section>
252     </chapter>
253    
254     <chapter>
255     <title>Reinstalling external modules</title>
256     <section>
257     <body>
258    
259     <p>
260     If you use any kernel modules that are not included in the kernel source tree
261 neysx 1.13 but are provided elsewhere in Portage (e.g. ALSA drivers and NVIDIA or ATI
262     graphics drivers), then you must reinstall these after upgrading the kernel.
263     This is as simple as re-merging the packages involved. For more information,
264     refer to the chapter on <e>Configuring the Kernel</e> in the <uri
265 nightmorph 1.14 link="/doc/en/handbook/">Gentoo Handbook</uri>.
266 swift 1.1 </p>
267    
268 swift 1.11 <p>
269     We provide you with an easy tool (<c>sys-kernel/module-rebuild</c>) which
270 nightmorph 1.14 rebuilds all the kernel modules you have installed using separate ebuilds for
271     the kernel at <path>/usr/src/linux</path>. Its use is straightforward. After
272     emerging it, simply run <c>module-rebuild populate</c> to populate the
273     database with a list of packages that will need to be rebuilt after upgrading
274     the kernel. Once you have finished upgrading or recompiling your kernel, run
275     <c>module-rebuild rebuild</c> to rebuild the drivers for your new kernel.
276 neysx 1.13 </p>
277    
278     <p>
279     For more information, run <c>module-rebuild</c> without any options to see a
280     list of commands that can be passed to the utility.
281 swift 1.11 </p>
282    
283 swift 1.1 </body>
284     </section>
285     </chapter>
286    
287     <chapter>
288     <title>Rebooting into the new kernel</title>
289     <section>
290     <body>
291    
292     <p>
293     Next, close all applications and reboot your system. If you followed the above
294 swift 1.5 instructions correctly, the boot loader menu should include an entry for the
295 swift 1.4 new kernel. Select the new kernel and let the system boot.
296 swift 1.1 </p>
297    
298     <p>
299 swift 1.4 Hopefully, your system successfully boots with the new kernel, and you can log
300     in to resume whatever you were doing. If this is the case, then the upgrade is
301     complete.
302 swift 1.1 </p>
303 neysx 1.13
304 swift 1.1 <p>
305 swift 1.4 If you made a mistake and the system fails to boot with the new kernel, reboot
306 swift 1.5 the system and select the entry from the boot loader that corresponds to the
307 swift 1.4 last known working kernel. You can then restart from the <uri link="#install">
308     Configuring, compiling, and installing the new kernel</uri> stage -- making
309     the appropriate changes to correct your mistake. In some cases, you might not
310     even need to reboot to do this (e.g. you missed a driver for an audio device,
311 swift 1.5 Ethernet adapter, etc.)
312 swift 1.1 </p>
313    
314     </body>
315     </section>
316     </chapter>
317    
318     <chapter>
319     <title>Running multiple kernels</title>
320     <section>
321     <body>
322    
323     <p>
324     You may have noticed, that when installing the sources for your newer kernel,
325 swift 1.4 the sources for your existing kernel were not removed. This is by design -- it
326 swift 1.1 allows you to easily switch between running different kernels.
327     </p>
328    
329     <p>
330     Switching between multiple kernels is as simple as leaving the kernel sources
331     under <path>/usr/src/</path> and leaving the <path>bzImage</path> binaries on
332 swift 1.5 your <path>/boot</path> partition (referenced by entries in your boot loader
333     configuration). Every time you boot up, you will be presented with a choice of
334     which kernel to boot into.
335 swift 1.1 </p>
336    
337     </body>
338     </section>
339     </chapter>
340    
341     <chapter>
342     <title>Removing older kernels</title>
343     <section>
344     <body>
345    
346     <p>
347     Continuing on from the last section, you may be happy with your new kernel and
348     not have any need to keep older kernel versions around. To easily remove all
349     sources for a particular kernel except for the newest one, you can take
350 swift 1.4 advantage of the <e>prune</e> option available through <c>emerge</c>. Continuing
351     the example using <c>gentoo-sources</c>:
352 swift 1.1 </p>
353    
354     <pre caption="Pruning old versions">
355 neysx 1.3 # <i>emerge -P gentoo-sources</i>
356 swift 1.1 </pre>
357    
358     <p>
359     In most cases, temporary files used during compilation will still remain under
360     the appropriate source directory under <path>/usr/src</path>. It is safe to
361     remove these using <c>rm</c>.
362     </p>
363    
364     <p>
365     You can also safely delete any modules that were used by this kernel. This can
366     be done by removing the appropriate directories under <path>/lib/modules/</path>
367     that relate to the kernel versions you are removing. Be careful not to delete
368     modules belonging to kernels that you still use!
369     </p>
370    
371     <p>
372     Finally, you can mount your <path>/boot</path> partition and remove the
373 jkt 1.10 <path>bzImage</path> file(s) for the kernel(s) you are pruning. You should also
374     edit your boot loader configuration so that it no longer references such
375     kernel(s).
376 swift 1.1 </p>
377    
378     </body>
379     </section>
380     </chapter>
381    
382     <chapter>
383 neysx 1.3 <title>Advanced: Using your old kernel .config to configure a new one</title>
384     <section>
385     <body>
386    
387     <p>
388     It is sometimes possible to save time by re-using the configuration file from
389     your old kernel when configuring the new one. Note that this is generally
390 swift 1.4 unsafe -- too many changes between every kernel release for this to be a
391 neysx 1.3 reliable upgrade path.
392     </p>
393    
394     <p>
395     The only situation where this is appropriate is when upgrading from one Gentoo
396     kernel revision to another. For example, the changes made between
397     <c>gentoo-sources-2.6.9-r1</c> and <c>gentoo-sources-2.6.9-r2</c> will be very
398     small, so it is usually OK to use the following method. However, it is not
399     appropriate to use it in the example used throughout this document: upgrading
400     from 2.6.8 to 2.6.9. Too many changes between the official releases, and the
401     method described below does not display enough context to the user, often
402     resulting in the user running into problems because they disabled options that
403     they really didn't want to.
404     </p>
405    
406     <p>
407 swift 1.5 To reuse your old <path>.config</path>, you simply need to copy it over and then
408     run <c>make oldconfig</c>. In the following example, we take the configuration
409     from <c>gentoo-sources-2.6.9-r1</c> and import it into
410 neysx 1.3 <c>gentoo-sources-2.6.9-r2</c>.
411     </p>
412    
413     <pre caption="Reusing your old config">
414     # <i>cd /usr/src/linux-2.6.9-gentoo-r2</i>
415     # <i>cp ../linux-2.6.9-gentoo-r1/.config .</i>
416     # <i>make oldconfig</i>
417     </pre>
418    
419     <p>
420     At this point, you may be asked to produce answers for configuration options
421     which have changed between the two versions. Once you have done that, you can
422     compile and install your kernel as normal, without having to go through the
423     <c>menuconfig</c> configuration process.
424     </p>
425    
426     </body>
427     </section>
428     </chapter>
429    
430     <chapter>
431 swift 1.1 <title>Problems after a kernel upgrade?</title>
432     <section>
433     <body>
434    
435     <p>
436     With the rapid development of the Linux kernel, it is inevitable that some
437 neysx 1.3 changes made from one kernel release to another may cause some problems. If you
438     have any issues with the latest versions of <uri
439     link="/doc/en/gentoo-kernel.xml#doc_chap2"> Gentoo-supported kernels</uri> then
440     please do report the issues to us.
441 swift 1.1 </p>
442    
443     </body>
444     </section>
445     </chapter>
446    
447     </guide>

  ViewVC Help
Powered by ViewVC 1.1.20