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1 neysx 1.1 <?xml version='1.0' encoding="UTF-8"?>
2     <!DOCTYPE guide SYSTEM "/dtd/guide.dtd">
3    
4 swift 1.7 <!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/migration-to-2.6.xml,v 1.6 2004/11/28 15:19:20 swift Exp $ -->
5 neysx 1.1
6     <guide link="/doc/en/migration-to-2.6.xml">
7    
8     <title>The complete Gentoo Linux 2.6 migration guide</title>
9    
10     <author title="Author">
11     <mail link="dsd@gentoo.org">Daniel Drake</mail>
12     </author>
13     <author title="Contributor">
14     <mail link="sergey_zlodey@mail.ru">Sergey Galkin</mail>
15     </author>
16     <author title="Contributor">
17     <mail link="svyatogor@gentoo.org">Sergey Kuleshov</mail>
18     </author>
19     <author title="Editor">
20     <mail link="neysx@gentoo.org">Xavier Neys</mail>
21     </author>
22 bennyc 1.3 <author title="Editor">
23     <mail link="bennyc@gentoo.org">Benny Chuang</mail>
24     </author>
25 neysx 1.1
26     <abstract>
27     This document will aid you in the process of migrating from Linux 2.4 to Linux
28     2.6, devfs to udev and OSS to ALSA.
29     </abstract>
30    
31 swift 1.7 <version>0.1.5</version>
32     <date>2004-12-22</date>
33 neysx 1.1
34     <chapter>
35     <title>Introduction</title>
36    
37     <section>
38     <title>Status of this document</title>
39     <body>
40    
41     <p>
42     The migration processes described in this document are not minor changes. This
43     document is in early stages and may be missing some details but hopefully the
44     main things have been covered. If you do try a migration, please <uri
45     link="http://bugs.gentoo.org">report</uri> any problem you might encounter so
46     that we can refine this guide.
47     </p>
48    
49     <p>
50     We are planning on making Linux 2.6 the default kernel for when 2005.0 is
51     released (for some arch's). At the same time, we will encourage all existing
52     users of those arch's to upgrade to Linux 2.6, as many will still be running
53     2.4. Your feedback on this document is much appreciated, so that when this
54     time comes, the document can be in good shape for the mass-migration.
55     </p>
56    
57     </body>
58     </section>
59    
60     <section>
61     <title>Whats new in Linux 2.6?</title>
62     <body>
63    
64     <p>
65     That is no easy question to answer. Linux 2.6 is the result of over 2 years
66     of rapid development and stabilisation of new features, and is architectually
67     quite different from its 2.4 counterpart. Some of the more major changes are
68     listed below:
69     </p>
70    
71     <ul>
72     <li>
73     Scheduler/Interactivity improvements: Linux feels very smooth on desktop
74     systems and copes much better than 2.4 while under load
75     </li>
76     <li>
77     Scalability: Linux now scales much better at both ends - on small embedded
78     devices and also systems with many processors
79     </li>
80     <li>Performance: Throughput from common applications is much improved</li>
81     <li>
82     Hardware support: Linux now supports many more architectures and hardware
83     devices out-of-the-box than any other operating system.
84     </li>
85     </ul>
86    
87     <p>
88     Joseph Pranevich has written a very detailed document, <uri
89     link="http://www.kniggit.net/wwol26.html">The Wonderful World Of Linux
90     2.6</uri> which you may be interested to glance over. If you are interested in
91     the more technical details, you can refer to <uri
92     link="http://www.linux.org.uk/~davej/docs/post-halloween-2.6.txt">The
93     post-halloween document</uri> - but bear in mind that this is somewhat outdated
94     now.
95     </p>
96    
97     </body>
98     </section>
99     <section>
100     <title>What is udev?</title>
101     <body>
102    
103     <p>
104     In the past, Gentoo has instructed users to use <e>devfs</e> for managing the
105     /dev directory, which contains a series of device interfaces to allow system
106     applications to communicate with hardware (through the kernel).
107     </p>
108    
109     <p>
110     <e>devfs</e>, whilst a good concept, has some internal problems, and has been
111     marked obselete in Linux 2.6.
112     </p>
113    
114     <p>
115     <e>udev</e> is the new way of managing device nodes. It addresses issues with
116     previous device managers, and also attempts to solve some other problems.
117     </p>
118    
119     <p>
120     The above may not mean much to you, but fear not, the hard working Gentoo
121     developers have put effort into making the migration from devfs very easy.
122     </p>
123    
124     </body>
125     </section>
126     <section>
127     <title>What is ALSA?</title>
128     <body>
129    
130     <p>
131     With Linux 2.4, chances are that you used OSS (open sound system) drivers to
132     power your sound card. OSS has been replaced by a newer and better set of sound
133     drivers: ALSA.
134     </p>
135    
136     <p>
137     ALSA, the Advanced Linux Sound Architecture, is a new set of sound drivers with
138     a new and improved API, present in the Linux 2.6 kernel. It is backwards
139     compatible with OSS applications, provided that you select the right kernel
140     configuration options!
141     </p>
142    
143     <note>
144     If you do not have any sound/audio hardware, you can safely skip over any
145     ALSA-related instructions in this document.
146     </note>
147    
148     </body>
149     </section>
150     </chapter>
151    
152     <chapter>
153     <title>Preparation</title>
154     <section>
155     <title>Get your system up-to-date</title>
156     <body>
157    
158     <p>
159     Some of the changes brought in with Linux 2.6 also required some changes in the
160     base system applications. Before continuing, you should ensure that your system
161     is relatively up-to-date, and to be perfectly sure, you should update all world
162     and system packages where updates are available.
163     </p>
164    
165     <p>
166     In particular, make sure you have the latest stable versions of the following
167     packages:
168     </p>
169    
170     <ul>
171     <li><c>sys-apps/baselayout</c></li>
172     <li><c>sys-apps/util-linux</c></li>
173     <li>
174     <c>sys-kernel/genkernel</c> (only if you wish to use genkernel as opposed
175     to manual configuration)
176     </li>
177     </ul>
178    
179     <pre caption="Updating all world packages">
180     # <i>emerge sync</i>
181     # <i>emerge -ua world</i>
182     </pre>
183    
184     </body>
185     </section>
186     <section>
187     <title>modutils vs module-init-tools</title>
188     <body>
189    
190     <p>
191     <c>sys-apps/modutils</c> is the package that provides tools such as
192     <c>modprobe</c>, <c>rmmod</c> and <c>insmod</c> for Linux 2.4.
193     </p>
194    
195     <p>
196     Linux 2.6 introduces a new module format, and therefore requires new tools for
197     handling modules. These are bundled up into the
198     <c>sys-apps/module-init-tools</c> package. </p>
199    
200     <p>
201     You should now remove modutils and install module-init-tools:
202     </p>
203    
204     <pre caption="Switching from modutils to module-init-tools">
205 swift 1.5 # <i>emerge unmerge sys-apps/modutils</i>
206 neysx 1.1 # <i>emerge module-init-tools</i>
207     </pre>
208    
209     <note>
210     Don't worry - even though you have just unmerged modutils, module-init-tools
211 bennyc 1.3 provides backwards compatibility for Linux 2.4, so you will still be
212 neysx 1.1 able to boot into Linux 2.4 and handle modules for that kernel.
213     </note>
214    
215     <note>
216     For the above reason, module-init-tools might already be installed and working
217     with your existing Linux 2.4 kernel. In this case, you don't need to worry
218     about this stage - your system is already ready to deal with Linux 2.6 modules.
219     </note>
220    
221     </body>
222     </section>
223     <section>
224     <title>Installing udev</title>
225     <body>
226    
227     <p>
228     There is no configuration involved here. Simply use <c>emerge</c> to install
229     udev:
230     </p>
231    
232     <pre caption="Installing udev">
233     # <i>emerge -a udev</i>
234     </pre>
235    
236 swift 1.7 <p>
237     You should now read the
238     <uri link="http://www.gentoo.org/doc/en/udev-guide.xml">Gentoo udev
239     Guide</uri> to get a more complete idea about the differences between udev
240     and devfs.
241     </p>
242    
243 neysx 1.1 </body>
244     </section>
245     <section>
246 swift 1.5 <title>Checking for essential device nodes</title>
247     <body>
248    
249     <p>
250     When the system boots up, the system requires some essential device nodes. As
251     udev is not included in the kernel, it is not activated immediately. To work
252     around this, you must ensure that you have some essential device nodes on your
253     disk.
254     </p>
255    
256     <p>
257     Our installation stage files will have created the required devices during the
258     initial installation. However, some users have reported that this is not the
259     case. We will use this opportunity to check that the device files exist, and
260     create them if they do not.
261     </p>
262    
263     <p>
264     As your existing device manager will be mounted at /dev, we cannot access it
265     directly. So we will bind-mount your root partition to another location and
266     access the /dev directory from there.
267     </p>
268    
269     <pre caption="Bind-mounting your root partition and listing static devices">
270     # <i>mkdir -p /mnt/temp</i>
271     # <i>mount -o bind / /mnt/temp</i>
272     # <i>cd /mnt/temp/dev</i>
273     # <i>ls -l console null</i>
274     </pre>
275    
276     <p>
277     If the above <e>ls</e> command reported that either <c>console</c> or
278     <c>null</c> do not exist, then you must create them yourself, as shown below.
279     </p>
280    
281     <pre caption="Creating the missing console and null nodes">
282     # <i>mknod -m 660 console c 5 1</i>
283     # <i>mknod -m 660 null c 1 3</i>
284     </pre>
285    
286     <p>
287     You should now unmount your bind-mounted root partition, even if you did not
288     have to create those devices:
289     </p>
290    
291     <pre caption="Unmounting the bind-mounted root">
292 swift 1.7 # <i>cd</i>
293 swift 1.5 # <i>umount /mnt/temp</i>
294 swift 1.6 # <i>rmdir /mnt/temp</i>
295 swift 1.5 </pre>
296    
297     </body>
298     </section>
299     <section>
300 neysx 1.1 <title>Installing ALSA utilities</title>
301     <body>
302    
303     <p>
304     ALSA requires you to have some packages installed, so that applications can use
305     the ALSA API. These packages will also allow you to control the mixer and
306     volume levels. Install the required utilities as follows:
307     </p>
308    
309     <pre caption="Installing ALSA utilities and libraries">
310     # <i>emerge -a alsa-lib alsa-utils alsa-tools alsa-headers alsa-oss</i>
311     </pre>
312    
313     </body>
314     </section>
315     </chapter>
316    
317     <chapter>
318     <title>Installing the Linux 2.6 sources</title>
319    
320     <section>
321     <title>Choosing and installing a kernel</title>
322     <body>
323    
324     <p>
325     The first thing you need to do is install sources of a 2.6 kernel of your
326     choice. The two Gentoo-supported 2.6 kernels are currently
327     <e>gentoo-dev-sources</e> (for desktops) and <e>hardened-dev-sources</e> (for
328     servers). There are others available, see the <uri
329     link="/doc/en/gentoo-kernel.xml">Gentoo Linux Kernel Guide</uri> for more
330     choices.
331     </p>
332    
333     <p>
334     In this guide, we'll use <c>gentoo-dev-sources</c> as an example. Install your
335     chosen set of kernel sources using the <c>emerge</c> utility:
336     </p>
337    
338     <pre caption="Installing gentoo-dev-sources">
339     # <i>emerge -a gentoo-dev-sources</i>
340     These are the packages that I would merge, in order:
341     Calculating dependencies ...done!
342     [ebuild N ] sys-kernel/gentoo-dev-sources-2.6.9-r2
343    
344     Do you want me to merge these packages? [Yes/No] <i>y</i>
345     </pre>
346    
347     </body>
348     </section>
349     <section>
350     <title>Updating the /usr/src/linux symbolic link</title>
351     <body>
352    
353     <p>
354     Various components of the Gentoo utilities rely on /usr/src/linux being a
355     symbolic link to the kernel sources that you are running (or wish to compile
356     against).
357     </p>
358    
359     <p>
360     We will now update our /usr/src/linux link to point at the kernel sources we
361     just installed. Continuing our example:
362     </p>
363    
364     <pre caption="Updating the /usr/src/linux softlink">
365     # <i>cd /usr/src</i>
366 neysx 1.4 # <i>ln -sfn linux-2.6.9-gentoo-r2 linux</i>
367 neysx 1.1 </pre>
368    
369     </body>
370     </section>
371     </chapter>
372    
373 swift 1.7 <chapter id="pitfalls">
374 neysx 1.1 <title>Known pitfalls with Linux 2.6 migration</title>
375     <section>
376     <body>
377    
378     <p>
379     Before we get stuck into configuring the kernel, I'll attempt to detail the
380     most common errors that people make when migrating to Linux 2.6, as some of
381     these points will influence the way you configure the new kernel.
382     </p>
383    
384     <note>
385     Not all of these points are relevant at this stage, but I will detail them all
386     here in one place, and you can refer back at your leisure.
387     </note>
388    
389     </body>
390     </section>
391     <section>
392     <title>Don't use "make oldconfig" with a 2.4 .config</title>
393     <body>
394    
395     <note>
396     If you don't understand what this means, don't worry, you won't make this
397     mistake if you follow the rest of this guide correctly.
398     </note>
399    
400     <p>
401     You'll be asked many many questions, since there have been a large amount of
402     changes. Many people who do try a <c>make oldconfig</c> from a 2.4 config end
403     up creating an unworkable kernel (e.g. no output on-screen, no input from
404     keyboard, etc). Please save yourself the trouble, and use the traditional
405     <c>menuconfig</c> configuration method just this once.
406     </p>
407    
408     </body>
409     </section>
410     <section>
411     <title>Don't use ide-scsi for CD/DVD writing</title>
412     <body>
413    
414     <p>
415     In Linux 2.4, the only way to achieve good CD/DVD writing results was to enable
416     the (rather ugly) <c>ide-scsi</c> emulation. Thankfully, the IDE layer in Linux
417     2.6 has been extended to support CD/DVD writers much better.
418     </p>
419    
420     <p>
421     You don't need to enable any extra options to support CD writing. Just be sure
422     <e>not</e> to enable <c>ide-scsi</c> as you used to.
423     </p>
424    
425     </body>
426     </section>
427     <section>
428     <title>PC Speaker is now a configurable option</title>
429     <body>
430    
431     <p>
432     You won't get your normal console beeps (or any response from the PC speaker at
433     all) unless you specifically enable the new PC speaker option
434     (<c>CONFIG_INPUT_PCSPKR</c>):
435     </p>
436    
437     <pre caption="Location of PC speaker option">
438     Device Drivers ---&gt;
439     Input device support ---&gt;
440     [*] Misc
441     &lt;*&gt; PC Speaker support
442     </pre>
443    
444     <note>
445     By "PC speaker", I am referring to the analogue speaker that beeps once when
446     your system is powering up, I am not referring to normal sound hardware used
447     for playing music, etc.
448     </note>
449    
450     </body>
451     </section>
452     <section>
453     <title>New USB Storage block device driver sometimes problematic</title>
454     <body>
455    
456     <p>
457     Very recently, a new USB storage device driver has been added to the kernel.
458     At the time of writing, this driver ("ub") is still in its early stages and
459     some users find it to be unreliable. If you have problems accessing your USB
460     hard disk, USB flash disk, USB card reader, or USB digital camera, then you
461     could try reverting to the older SCSI-style driver:
462     </p>
463    
464     <pre caption="Disabling ub">
465     Device Drivers ---&gt;
466     Block devices ---&gt;
467     &lt; &gt; Low Performance USB Block driver
468     </pre>
469    
470     <note>
471     The older SCSI-style driver (USB Mass Storage support) is enabled by default.
472     It can be found under "Device Drivers --&gt; USB support", but will generally
473     not come into effect while ub is also present.
474     </note>
475    
476     </body>
477     </section>
478     <section>
479     <title>usbdevfs renamed to usbfs</title>
480     <body>
481    
482     <p>
483     If you have edited your <path>/etc/fstab</path> file to customise the way that
484     the USB device filesystem gets mounted, you may have to modify the filesystem
485     type from <e>usbdevfs</e> to <e>usbfs</e>.
486     </p>
487    
488     <note>
489     Recent 2.4 kernels will also allow you to use "usbfs" as well as "usbdevfs", so
490     you aren't breaking any backwards compatibility by doing this.
491     </note>
492    
493     </body>
494     </section>
495     <section>
496     <title>Don't renice X</title>
497     <body>
498    
499     <p>
500     If you are a desktop 2.4 user, you may have hacked your system into running X
501     at a higher priority, as in some cases it seems to provide better desktop
502     performance.
503     </p>
504    
505     <p>
506     There have been many scheduler changes in 2.6 which change this behaviour. If
507     you continue to run X at a higher priority, it will do exactly what it is
508     supposed to (run the <e>display server</e> at a very high priority) and you
509     will notice consequences such as sound stuttering and slow application load
510     times because your CPU is spending too long serving X and only X.
511     </p>
512    
513     <p>
514     In Linux 2.6, you no longer need to renice desktop applications to get good
515     interactivity. Please remove your "niceness" hacks!
516     </p>
517    
518     </body>
519     </section>
520     <section>
521     <title>X11 config file should now use /dev/input/mice</title>
522     <body>
523    
524     <p>
525     One of the changes that a default udev configuration introduces is different
526     organisation of the mouse device nodes. Previously, you would have had nodes
527     such as <path>/dev/psaux</path> and <path>/dev/mouse</path>. You will now have
528     nodes such as <path>/dev/input/mouse0</path>, <path>/dev/input/mouse1</path>,
529     and a collective <path>/dev/input/mice</path> node which combines movements
530     from all mice.
531     </p>
532    
533     <p>
534     Since the old X configurations typically reference <path>/dev/mouse</path> or
535     <path>/dev/psaux</path> then you may get an error similar to the one shown
536     below when you attempt to start X11:
537     </p>
538    
539     <pre caption="Common error when starting X on a udev system for the first time">
540     (EE) xf86OpenSerial: Cannot open device /dev/mouse
541     No such file or directory.
542     (EE) Mouse0: cannot open input device
543     (EE) PreInit failed for input device "Mouse0"
544     No core pointer
545     </pre>
546    
547     <p>
548     To correct this, open your X11 config in a text editor, and update the mouse
549     <e>InputDevice</e> section to use the <path>/dev/input/mice</path> device. An
550     example is shown below:
551     </p>
552    
553     <pre caption="Opening your X11 config file">
554     # <i>nano -w /etc/X11/xorg.conf</i>
555     </pre>
556    
557     <note>
558     If you are still using XFree86, your config file will be
559     <path>/etc/X11/XF86Config</path>
560     </note>
561    
562     <pre caption="Sample mouse InputDevice section">
563     Section "InputDevice"
564     Identifier "Mouse0"
565     Driver "mouse"
566     Option "Protocol" "auto"
567     Option "Device" "/dev/input/mice"
568     EndSection
569     </pre>
570    
571     </body>
572     </section>
573     </chapter>
574    
575     <chapter id="conf">
576     <title>Configuring, building, and installing the kernel</title>
577     <section>
578     <body>
579    
580     <p>
581     As with Linux 2.4, you have two options for managing your new kernel build.
582     </p>
583    
584     <ol>
585     <li>
586     The default method is to configure your kernel manually. This may seem
587     daunting but is the preferred way as long as you know your system. If you
588     wish to configure your new kernel manually, please continue on to the <uri
589     link="#manual">next chapter</uri>.
590     </li>
591     <li>
592     The alternative option is to use our <c>genkernel</c> utility to
593     automatically configure, compile, and install a kernel for you. If you wish
594     to use <c>genkernel</c> then skip over the next chapter and proceed with
595     <uri link="#genkernel">using genkernel</uri>.
596     </li>
597     </ol>
598    
599     </body>
600     </section>
601     </chapter>
602    
603     <chapter id="manual">
604     <title>Default: Manual configuration</title>
605     <section>
606     <title>Configuring the kernel</title>
607     <body>
608    
609     <p>
610     We'll now get on with configuring the kernel. Open menuconfig in the usual way:
611     </p>
612    
613     <pre caption="Invoking menuconfig">
614     # <i>cd /usr/src/linux</i>
615     # <i>make menuconfig</i>
616     </pre>
617    
618     <p>
619     You will probably be familiar with using menuconfig from configuring 2.4
620     kernels. Fortunately, the front end has barely changed at all, but you will
621     observe much better organisation of kernel options, plus <e>many</e> new
622     options that weren't present in 2.4.
623     </p>
624    
625     <p>
626     Be sure to enable the following important kernel options:
627     </p>
628    
629     <pre caption="Required kernel options">
630     File systems ---&gt;
631     Pseudo Filesystems ---&gt;
632     [*] /proc file system support
633     [*] Virtual memory file system support (former shm fs)
634    
635     <comment>(the following are required for udev):</comment>
636     General setup ---&gt;
637     [*] Support for hot-pluggable devices
638    
639     Device Drivers ---&gt;
640     Block devices ---&gt;
641     &lt;*&gt; RAM disk support
642    
643     <comment>(the following are required for ALSA):</comment>
644     Device Drivers ---&gt;
645     Sound ---&gt;
646     &lt;*&gt; Sound card support
647     Advanced Linux Sound Architecture ---&gt;
648     &lt;M&gt; Advanced Linux Sound Architecture
649     &lt;M&gt; Sequencer support
650     &lt;M&gt; OSS Mixer API
651     [*] OSS Sequencer API
652     <comment> (and dont forget to select your soundcard from the submenus!)</comment>
653     </pre>
654    
655     <warn>
656     Previously you may have included support for the <path>/dev</path> file system
657     (now marked OBSOLETE). Do not enable devfs support. We have installed udev,
658     which we will be using instead of devfs from now on.
659     </warn>
660    
661     <p>
662     Also, remember to enable support for the filesystems that you use, and the
663     hardware present in your system. Be sure to enable support for the IDE
664     controller on your motherboard if you wish to benefit from fast DMA disk
665     access. Refer to the <uri
666     link="/doc/en/handbook/handbook-x86.xml?part=1&amp;chap=7">Configuring the
667     Kernel</uri> section of the <uri link="/doc/en/handbook/index.xml">Gentoo
668     Handbook</uri> for additional guidance here.
669     </p>
670    
671     </body>
672     </section>
673     <section>
674     <title>Building the kernel</title>
675     <body>
676    
677     <p>
678     Now that we have configured the kernel, we can start the compilation process:
679     </p>
680    
681     <pre caption="Compiling the kernel source">
682     # <i>make &amp;&amp; make modules_install</i>
683     </pre>
684    
685     <note>
686     You may recall having to run <c>make dep</c> with Linux 2.4 sources. This is no
687     longer required.
688     </note>
689    
690     <p>
691     Wait for the kernel compilation to complete (and observe the much more readable
692     compilation output).
693     </p>
694    
695     </body>
696     </section>
697     <section>
698     <title>Installing the kernel</title>
699     <body>
700    
701     <p>
702     The next step is mounting your <path>/boot</path> partition and copying the
703     kernel image over. You must then update your bootloader config manually.
704     </p>
705    
706     <pre caption="Installing the kernel">
707     # <i>mount /boot</i>
708     # <i>cp arch/i386/boot/bzImage /boot/bzImage-2.6.9-gentoo-r2</i>
709     # <i>cp System.map /boot/System.map-2.6.9-gentoo-r2</i>
710     </pre>
711    
712     <p>
713     Note that the above instructions are examples only, you should follow your
714     usual procedure of updating kernels by following the instructions in the <uri
715     link="/doc/en/handbook/index.xml">Gentoo Handbook</uri> (see the <uri
716     link="/doc/en/handbook/handbook-x86.xml?part=1&amp;chap=7">Configuring the
717     Kernel</uri> chapter).
718     </p>
719    
720     <p>
721     When updating your bootloader config, do not remove the old entry pointing at
722     your 2.4 kernel. This way, you will easily be able to switch between the two if
723     something is not working.
724     </p>
725    
726     <p>
727     Now continue onto the <uri link="#modules">Module Configuration</uri> section.
728     </p>
729    
730     </body>
731     </section>
732     </chapter>
733    
734     <chapter id="genkernel">
735     <title>Alternative: Using genkernel</title>
736     <section>
737     <body>
738    
739     <p>
740     If you prefer to use genkernel instead of manually configuring your kernel, you
741     will be happy to hear that using genkernel to produce 2.6 kernels is very
742     similar to the process you performed when producing your previous 2.4 kernel.
743     </p>
744    
745     <p>
746     You should invoke genkernel as shown below:
747     </p>
748    
749     <pre caption="Invoking genkernel with some common arguments">
750     # <i>genkernel --udev --menuconfig --bootloader=grub all</i>
751     </pre>
752    
753     <p>
754     In the above example, we also take advantage of genkernel features to open
755     menuconfig to allow you to customise the kernel configuration (if you wish),
756     and to update the grub bootloader configuration after compilation.
757     </p>
758    
759     <p>
760     You should choose genkernel arguments that suit you, but do not forget to
761     include the <c>--udev</c> argument! Refer to the <uri
762     link="/doc/en/genkernel.xml">Gentoo Linux Genkernel Guide</uri> and the <uri
763     link="/doc/en/handbook/handbook-x86.xml?part=1&amp;chap=7">Configuring the
764     Kernel</uri> chapter of the <uri link="/doc/en/handbook/index.xml">Gentoo
765     Handbook</uri> for additional information.
766     </p>
767    
768 swift 1.7 <p>
769     If you choose to update your bootloader config yourself, then you must
770     remember to include the <c>udev</c> kernel parameter. A sample <e>grub</e>
771     config section is shown below, but remember to adjust the <e>real_root</e>
772     parameter for your system.
773     </p>
774    
775     <pre caption="Sample GRUB config for genkernel + udev">
776     title=Gentoo Linux (2.6 kernel)
777     root (hd0,0)
778     kernel /kernel-2.6.9-gentoo-r2 <i>udev</i> root=/dev/ram0 init=/linuxrc ramdisk=8192 real_root=/dev/hda3
779     initrd /initrd-2.6.9-gentoo-r2
780     </pre>
781    
782 neysx 1.1 </body>
783     </section>
784     </chapter>
785    
786     <chapter id="modules">
787     <title>Module Configuration</title>
788    
789     <section>
790     <title>Installing external modules</title>
791     <body>
792    
793     <p>
794     Many users will additionally rely on kernel modules that are built outside of
795     the kernel tree. Common examples are the binary ATI and Nvidia graphics
796     drivers. You now need to install those modules, which will compile against the
797     2.6 sources found at <path>/usr/src/linux</path>. This is the usual case of
798     <c>emerge packagename</c> for all the external modules you are used to using
799     with 2.4.
800     </p>
801    
802     <p>
803     Refer again to the <uri
804     link="/doc/en/handbook/handbook-x86.xml?part=1&amp;chap=7">Configuring the
805     Kernel</uri> chapter of the <uri link="/doc/en/handbook/index.xml">Gentoo
806     Handbook</uri> for more info.
807     </p>
808    
809     </body>
810     </section>
811     <section>
812     <title>Autoloading modules</title>
813     <body>
814    
815     <p>
816     You may have decided to compile some kernel components as modules (as opposed
817     to compiled directly into the kernel) and would like to have them autoloaded on
818     bootup like you did with 2.4. Also, if you installed any external modules from
819     the portage tree (as described above) you will probably want to autoload them
820     too.
821     </p>
822    
823     <p>
824     You can achieve this similarly as to how you did with 2.4. Simply open up the
825     file <path>/etc/modules.autoload.d/kernel-2.6</path> in a text editor and list
826     the names of the modules you would like autoloaded.
827     </p>
828    
829     <pre caption="Opening the module autoload list in nano">
830     # <i>nano -w /etc/modules.autoload.d/kernel-2.6</i>
831     </pre>
832    
833     <pre caption="Sample autoload list to load the 3c59x and nvidia modules">
834     # /etc/modules.autoload.d/kernel-2.6: kernel modules to load when system boots.
835     #
836     # Note that this file is for 2.6 kernels.
837     #
838     # Add the names of modules that you'd like to load when the system
839     # starts into this file, one per line. Comments begin with # and
840     # are ignored. Read man modules.autoload for additional details.
841    
842     3c59x
843     nvidia
844     </pre>
845    
846     </body>
847     </section>
848     <section>
849     <title>Configuring the ALSA modules</title>
850     <body>
851    
852     <p>
853     You will have noticed that we chose to compile ALSA as modules. We can now
854     configure ALSA's behaviour easily. However, we also need to configure which
855     modules are to be loaded. Open up <path>/etc/modules.d/alsa</path> in your text
856     editor:
857     </p>
858    
859     <pre caption="Opening /etc/modules.d/alsa in nano">
860     # <i>nano -w /etc/modules.d/alsa</i>
861     </pre>
862    
863     <p>
864     Now look for the section marked as <e>IMPORTANT</e>. In most cases, you just
865     need to uncomment and modify the snd-card-0 and snd-slot-0 aliases.
866     </p>
867    
868     <pre caption="Sample section of /etc/modules.d/alsa">
869     ## IMPORTANT:
870     ## You need to customise this section for your specific sound card(s)
871     ## and then run `update-modules' command.
872     ## Read alsa-driver's INSTALL file in /usr/share/doc for more info.
873     ##
874     ## ALSA portion
875    
876     # My laptop uses the snd-maestro3 driver
877     alias snd-card-0 snd-maestro3
878    
879     ## OSS/Free portion
880    
881     # Generally all you need to do is uncomment this line:
882     alias sound-slot-0 snd-card-0
883     </pre>
884    
885     <p>
886     For more info on which driver name to use, consult the <uri
887     link="/doc/en/alsa-guide.xml">Gentoo Linux ALSA Guide</uri>. Remember to prefix
888     it with <e>snd-</e> in this file.
889     </p>
890    
891     <p>
892     Finally, set the <c>alsasound</c> init script to be executed on bootup:
893     </p>
894    
895     <pre caption="Adding alsasound to default runlevel">
896     # <i>rc-update add alsasound boot</i>
897     </pre>
898    
899     </body>
900     </section>
901     </chapter>
902    
903     <chapter>
904     <title>Booting into Linux 2.6</title>
905     <section>
906     <body>
907    
908     <p>
909     It's now time to boot into Linux 2.6. Close all applications and reboot:
910     </p>
911    
912     <pre caption="Rebooting">
913     # <i>umount /boot</i>
914     # <i>reboot</i>
915     </pre>
916    
917     <p>
918     When you reboot, if you followed this document correctly so far, you will have
919     the option of either loading Linux 2.4 or Linux 2.6 from your bootloader.
920     Choose Linux 2.6.
921     </p>
922    
923     <p>
924     Once the system has booted, check that things are working. If you made a
925     mistake in the kernel configuration, don't worry, you can skip back to the
926     <uri link="#conf">Configuring, building, and installing the kernel</uri>
927     section, make your change, recompile and install new kernel image, reboot, and
928     try again!
929     </p>
930    
931     </body>
932     </section>
933     <section>
934     <title>Unmuting ALSA channels</title>
935     <body>
936    
937     <p>
938     By default, ALSA channels are muted, so you won't hear anything when you go to
939     play a sound. You need to unmute them now. Run the <c>alsamixer</c> program
940     from a console and use the arrow keys to move around and adjust volumes, and
941     the M key to mute and unmute. Read the <uri
942     link="/doc/en/alsa-guide.xml">Gentoo Linux ALSA Guide</uri> for more complete
943     documentation and other ways to do this.
944     </p>
945    
946     <note>
947     The alsasound init script that we put in the default runlevel will save mixer
948     levels on shutdown and restore them on bootup. You won't need to set all these
949     volumes every time you boot!
950     </note>
951    
952     </body>
953     </section>
954 swift 1.7 <section>
955     <title>Any immediate problems?</title>
956     <body>
957    
958     <p>
959     At this stage you should refer back to the <uri link="#pitfalls">Known
960     pitfalls with Linux 2.6 migration</uri> section which may be helpful with any
961     issues you encounter immediately.
962     </p>
963    
964     </body>
965     </section>
966 neysx 1.1 </chapter>
967    
968     <chapter>
969     <title>Header files and NPTL</title>
970     <section>
971     <body>
972    
973     <p>
974     By now you are running Linux 2.6 and hopefully have all issues ironed out. You
975     should now update your Linux kernel header files and re-merge glibc so that
976     userspace applications can take advantage of new Linux 2.6 features.
977     </p>
978    
979     <pre caption="Updating to linux26-headers">
980 swift 1.2 # <i>emerge unmerge linux-headers</i>
981 neysx 1.1 # <i>emerge linux26-headers</i>
982     </pre>
983    
984     <p>
985     After updating your headers package, you should generally re-merge glibc.
986     There is a new feature here that you may be interested in - NPTL. NPTL is a new
987     threading model present in Linux 2.6, which features much quicker thread create
988     and destroy times. This won't make much of a difference to most systems, but
989     you may wish to enable it during this migration process! To enable NPTL, edit
990     <path>/etc/make.conf</path>, adding <e>nptl</e> to your USE variable.
991     </p>
992    
993     <warn>
994     With the current stable glibc ebuilds, you will be unable to boot a 2.4 kernel
995     after compiling glibc with USE="nptl". Be warned, be careful!
996     </warn>
997    
998     <p>
999     Now re-merge glibc (you should do this even if you did not choose to enable
1000     NPTL).
1001     </p>
1002    
1003     <pre caption="Reinstalling glibc against the new kernel headers">
1004     # <i>emerge -a glibc</i>
1005     </pre>
1006    
1007     <p>
1008     If you enabled NPTL, existing binaries will not use it until they are
1009     recompiled. However, any binaries compiled from this point onwards <e>will</e>
1010     use NPTL. You may wish to recompile all binaries now, e.g.:
1011     </p>
1012    
1013     <pre caption="Recompiling all packages on the system">
1014     # <i>emerge -e world</i>
1015     </pre>
1016    
1017     <p>
1018     Alternatively, you can just let your system "naturally" convert itself to NPTL
1019     as you update to newer versions of packages when they are released.
1020     </p>
1021    
1022     </body>
1023     </section>
1024     </chapter>
1025    
1026     <chapter>
1027     <title>Closing remarks</title>
1028     <section>
1029     <title>Problems?</title>
1030     <body>
1031    
1032     <p>
1033     With the incredible amount of work that went into Linux 2.6, it is sometimes
1034     inevitable that things which used to work fine, no longer function as expected.
1035     </p>
1036    
1037     <p>
1038     If you have any problems with your 2.6 kernel, and you can confirm that this
1039     problem does not exist with Linux 2.4, then please open a bug with us on our
1040     <uri link="http://bugs.gentoo.org">Bugzilla</uri>. We will investigate the
1041     issue, and if we find that it is a problem in the mainline kernel, we may then
1042     ask you to file a report at the central kernel bugzilla.
1043     </p>
1044    
1045     </body>
1046     </section>
1047     <section>
1048     <title>Conclusion</title>
1049     <body>
1050    
1051     <p>
1052     Hopefully you have just completed a smooth migration and you are enjoying the
1053     benefits which Linux 2.6 brings over 2.4. As I mentioned at the start, we are
1054     looking for feedback on this document - even if your migration went perfectly
1055     smoothly. Please <mail link="dsd@gentoo.org">mail me</mail> your feedback so
1056     that we can get this document in perfect shape for when 2005.0 comes around.
1057     Thanks!
1058     </p>
1059    
1060     </body>
1061     </section>
1062     </chapter>
1063     </guide>

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