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1 <?xml version='1.0' encoding="UTF-8"?>
2 <!DOCTYPE guide SYSTEM "/dtd/guide.dtd">
3
4 <!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/migration-to-2.6.xml,v 1.12 2005/02/07 19:23:22 swift Exp $ -->
5
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 <author title="Editor">
23 <mail link="bennyc@gentoo.org">Benny Chuang</mail>
24 </author>
25
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, OSS to ALSA, and LVM to LVM2.
29 </abstract>
30
31 <version>0.2.4</version>
32 <date>2005-04-02</date>
33
34 <chapter>
35 <title>Introduction</title>
36
37 <section>
38 <title>Whats new in Linux 2.6?</title>
39 <body>
40
41 <p>
42 That is no easy question to answer. Linux 2.6 is the result of over 2 years
43 of rapid development and stabilisation of new features, and is architectually
44 quite different from its 2.4 counterpart. Some of the more major changes are
45 listed below:
46 </p>
47
48 <ul>
49 <li>
50 Scheduler/Interactivity improvements: Linux feels very smooth on desktop
51 systems and copes much better than 2.4 while under load
52 </li>
53 <li>
54 Scalability: Linux now scales much better at both ends - on small embedded
55 devices and also systems with many processors
56 </li>
57 <li>Performance: Throughput from common applications is much improved</li>
58 <li>
59 Hardware support: Linux now supports many more architectures and hardware
60 devices out-of-the-box than any other operating system.
61 </li>
62 </ul>
63
64 <p>
65 Joseph Pranevich has written a very detailed document, <uri
66 link="http://www.kniggit.net/wwol26.html">The Wonderful World Of Linux
67 2.6</uri> which you may be interested to glance over. If you are interested in
68 the more technical details, you can refer to <uri
69 link="http://www.linux.org.uk/~davej/docs/post-halloween-2.6.txt">The
70 post-halloween document</uri> - but bear in mind that this is somewhat outdated
71 now.
72 </p>
73
74 </body>
75 </section>
76 <section>
77 <title>What is udev?</title>
78 <body>
79
80 <p>
81 In the past, Gentoo has instructed users to use <e>devfs</e> for managing the
82 /dev directory, which contains a series of device interfaces to allow system
83 applications to communicate with hardware (through the kernel).
84 </p>
85
86 <p>
87 <e>devfs</e>, whilst a good concept, has some internal problems, and has been
88 marked obselete in Linux 2.6.
89 </p>
90
91 <p>
92 <e>udev</e> is the new way of managing device nodes. It addresses issues with
93 previous device managers, and also attempts to solve some other problems.
94 </p>
95
96 <p>
97 The above may not mean much to you, but fear not, the hard working Gentoo
98 developers have put effort into making the migration from devfs very easy.
99 </p>
100
101 </body>
102 </section>
103 <section>
104 <title>What is ALSA?</title>
105 <body>
106
107 <p>
108 With Linux 2.4, chances are that you used OSS (open sound system) drivers to
109 power your sound card. OSS has been replaced by a newer and better set of sound
110 drivers: ALSA.
111 </p>
112
113 <p>
114 ALSA, the Advanced Linux Sound Architecture, is a new set of sound drivers with
115 a new and improved API, present in the Linux 2.6 kernel. It is backwards
116 compatible with OSS applications, provided that you select the right kernel
117 configuration options!
118 </p>
119
120 <note>
121 If you do not have any sound/audio hardware, you can safely skip over any
122 ALSA-related instructions in this document.
123 </note>
124
125 </body>
126 </section>
127 <section>
128 <title>What is LVM?</title>
129 <body>
130
131 <p>
132 <e>Logical Volume Management</e> (LVM) exists as set of tools allowing you to
133 manage your disk storage in a very flexible manner. Amongst other things, it
134 allows powerful control over partitions (e.g. resizing without reboot), and
135 makes operations like device changes relatively simple. LVM acts as an
136 alternative to standard partition-based disk management.
137 </p>
138
139 <p>
140 LVM support has historically been implemented in Linux 2.4. Linux 2.6 features
141 a new version of LVM, named <e>LVM2</e>. The migration process requires you to
142 install new versions of the user-level tools (covered later in this document)
143 but will leave your data intact!
144 </p>
145
146 <p>
147 <e>If you do not currently use LVM for data-storage management, then LVM2
148 migration does not apply to you.</e> If this is the case, you can safely ignore
149 any parts of this document referencing LVM/LVM2. Upgrading to Linux 2.6 does
150 <e>not</e> require you to store your data on LVM partitions - you can keep
151 your data in the standard partition-format as it always has been.
152 </p>
153
154 <p>
155 If you are not a LVM user, but you think LVM2 sounds useful for you, you can
156 convert your disks to this format at a later date, by following the
157 <uri link="http://www.gentoo.org/doc/en/lvm2.xml">Gentoo LVM2 Installation
158 Guide</uri>. For now, lets just concentrate on getting a smooth 2.6 migration
159 underway.
160 </p>
161
162 </body>
163 </section>
164 </chapter>
165
166 <chapter>
167 <title>Preparation</title>
168 <section>
169 <title>Get your system up-to-date</title>
170 <body>
171
172 <p>
173 Some of the changes brought in with Linux 2.6 also required some changes in the
174 base system applications. Before continuing, you should ensure that your system
175 is relatively up-to-date, and to be perfectly sure, you should update all world
176 and system packages where updates are available.
177 </p>
178
179 <p>
180 In particular, make sure you have the latest stable versions of the following
181 packages:
182 </p>
183
184 <ul>
185 <li><c>sys-apps/baselayout</c></li>
186 <li><c>sys-apps/util-linux</c></li>
187 <li>
188 <c>sys-kernel/genkernel</c> (only if you wish to use genkernel as opposed
189 to manual configuration)
190 </li>
191 </ul>
192
193 <pre caption="Updating all world packages">
194 # <i>emerge --sync</i>
195 # <i>emerge -ua world</i>
196 </pre>
197
198 </body>
199 </section>
200 <section>
201 <title>modutils vs module-init-tools</title>
202 <body>
203
204 <p>
205 <c>sys-apps/modutils</c> is the package that provides tools such as
206 <c>modprobe</c>, <c>rmmod</c> and <c>insmod</c> for Linux 2.4.
207 </p>
208
209 <p>
210 Linux 2.6 introduces a new module format, and therefore requires new tools for
211 handling modules. These are bundled up into the
212 <c>sys-apps/module-init-tools</c> package. </p>
213
214 <p>
215 You should now remove modutils and install module-init-tools:
216 </p>
217
218 <pre caption="Switching from modutils to module-init-tools">
219 # <i>emerge --unmerge sys-apps/modutils</i>
220 # <i>emerge module-init-tools</i>
221 </pre>
222
223 <note>
224 Don't worry - even though you have just unmerged modutils, module-init-tools
225 provides backwards compatibility for Linux 2.4, so you will still be
226 able to boot into Linux 2.4 and handle modules for that kernel.
227 </note>
228
229 <note>
230 For the above reason, module-init-tools might already be installed and working
231 with your existing Linux 2.4 kernel. In this case, you don't need to worry
232 about this stage - your system is already ready to deal with Linux 2.6 modules.
233 </note>
234
235 </body>
236 </section>
237 <section>
238 <title>Installing udev</title>
239 <body>
240
241 <p>
242 There is no configuration involved here. Simply use <c>emerge</c> to install
243 udev:
244 </p>
245
246 <pre caption="Installing udev">
247 # <i>emerge -a udev</i>
248 </pre>
249
250 <p>
251 You should now read the
252 <uri link="http://www.gentoo.org/doc/en/udev-guide.xml">Gentoo udev
253 Guide</uri> to get a more complete idea about the differences between udev
254 and devfs.
255 </p>
256
257 </body>
258 </section>
259 <section>
260 <title>Checking for essential device nodes</title>
261 <body>
262
263 <p>
264 When the system boots up, the system requires some essential device nodes. As
265 udev is not included in the kernel, it is not activated immediately. To work
266 around this, you must ensure that you have some essential device nodes on your
267 disk.
268 </p>
269
270 <p>
271 Our installation stage files will have created the required devices during the
272 initial installation. However, some users have reported that this is not the
273 case. We will use this opportunity to check that the device files exist, and
274 create them if they do not.
275 </p>
276
277 <p>
278 As your existing device manager will be mounted at /dev, we cannot access it
279 directly. So we will bind-mount your root partition to another location and
280 access the /dev directory from there.
281 </p>
282
283 <pre caption="Bind-mounting your root partition and listing static devices">
284 # <i>mkdir -p /mnt/temp</i>
285 # <i>mount -o bind / /mnt/temp</i>
286 # <i>cd /mnt/temp/dev</i>
287 # <i>ls -l console null</i>
288 </pre>
289
290 <p>
291 If the above <e>ls</e> command reported that either <c>console</c> or
292 <c>null</c> do not exist, then you must create them yourself, as shown below.
293 </p>
294
295 <pre caption="Creating the missing console and null nodes">
296 # <i>mknod -m 660 console c 5 1</i>
297 # <i>mknod -m 660 null c 1 3</i>
298 </pre>
299
300 <p>
301 You should now unmount your bind-mounted root partition, even if you did not
302 have to create those devices:
303 </p>
304
305 <pre caption="Unmounting the bind-mounted root">
306 # <i>cd</i>
307 # <i>umount /mnt/temp</i>
308 # <i>rmdir /mnt/temp</i>
309 </pre>
310
311 </body>
312 </section>
313 <section>
314 <title>Installing ALSA utilities</title>
315 <body>
316
317 <p>
318 ALSA requires you to have some packages installed, so that applications can use
319 the ALSA API. These packages will also allow you to control the mixer and
320 volume levels. Install the required utilities as follows:
321 </p>
322
323 <pre caption="Installing ALSA utilities and libraries">
324 # <i>emerge -a alsa-lib alsa-utils alsa-tools alsa-headers alsa-oss</i>
325 </pre>
326
327 </body>
328 </section>
329 </chapter>
330
331 <chapter>
332 <title>Installing the Linux 2.6 sources</title>
333
334 <section>
335 <title>Choosing and installing a kernel</title>
336 <body>
337
338 <p>
339 The first thing you need to do is install sources of a 2.6 kernel of your
340 choice. The two Gentoo-supported 2.6 kernels are currently
341 <e>gentoo-sources</e> (for desktops) and <e>hardened-dev-sources</e> (for
342 servers). There are others available, see the <uri
343 link="/doc/en/gentoo-kernel.xml">Gentoo Linux Kernel Guide</uri> for more
344 choices.
345 </p>
346
347 <p>
348 In this guide, we'll use <c>gentoo-sources</c> as an example. Install your
349 chosen set of kernel sources using the <c>emerge</c> utility:
350 </p>
351
352 <pre caption="Installing gentoo-sources">
353 # <i>emerge -a gentoo-sources</i>
354 These are the packages that I would merge, in order:
355 Calculating dependencies ...done!
356 [ebuild NS ] sys-kernel/gentoo-sources-2.6.10-r4
357
358 Do you want me to merge these packages? [Yes/No] <i>y</i>
359 </pre>
360
361 <p>
362 When performing the above <c>emerge</c> command, if you find that it wants to
363 install a 2.4 version of gentoo-sources (e.g. <c>gentoo-sources-2.4.26</c>),
364 then it means that the profile you are using is not designed for Linux 2.6
365 users. Please follow the
366 <uri link="http://www.gentoo.org/proj/en/releng/release/2005.0/releng/profile-update.xml">
367 2005.0 profile update document</uri> to switch to a 2.6-based profile, and
368 retry installing 2.6 kernel sources.
369 </p>
370
371 </body>
372 </section>
373 <section>
374 <title>Updating the /usr/src/linux symbolic link</title>
375 <body>
376
377 <p>
378 Various components of the Gentoo utilities rely on /usr/src/linux being a
379 symbolic link to the kernel sources that you are running (or wish to compile
380 against).
381 </p>
382
383 <p>
384 We will now update our /usr/src/linux link to point at the kernel sources we
385 just installed. Continuing our example:
386 </p>
387
388 <pre caption="Updating the /usr/src/linux softlink">
389 # <i>cd /usr/src</i>
390 # <i>ln -sfn linux-2.6.10-gentoo-r4 linux</i>
391 </pre>
392
393 </body>
394 </section>
395 </chapter>
396
397 <chapter id="pitfalls">
398 <title>Known pitfalls with Linux 2.6 migration</title>
399 <section>
400 <body>
401
402 <p>
403 Before we get stuck into configuring the kernel, I'll attempt to detail the
404 most common errors that people make when migrating to Linux 2.6, as some of
405 these points will influence the way you configure the new kernel.
406 </p>
407
408 <note>
409 Not all of these points are relevant at this stage, but I will detail them all
410 here in one place, and you can refer back at your leisure.
411 </note>
412
413 </body>
414 </section>
415 <section>
416 <title>Don't use "make oldconfig" with a 2.4 .config</title>
417 <body>
418
419 <note>
420 If you don't understand what this means, don't worry, you won't make this
421 mistake if you follow the rest of this guide correctly.
422 </note>
423
424 <p>
425 You'll be asked many many questions, since there have been a large amount of
426 changes. Many people who do try a <c>make oldconfig</c> from a 2.4 config end
427 up creating an unworkable kernel (e.g. no output on-screen, no input from
428 keyboard, etc). Please save yourself the trouble, and use the traditional
429 <c>menuconfig</c> configuration method just this once.
430 </p>
431
432 </body>
433 </section>
434 <section>
435 <title>Don't use ide-scsi for CD/DVD writing</title>
436 <body>
437
438 <p>
439 In Linux 2.4, the only way to achieve good CD/DVD writing results was to enable
440 the (rather ugly) <c>ide-scsi</c> emulation. Thankfully, the IDE layer in Linux
441 2.6 has been extended to support CD/DVD writers much better.
442 </p>
443
444 <p>
445 You don't need to enable any extra options to support CD writing. Just be sure
446 <e>not</e> to enable <c>ide-scsi</c> as you used to.
447 </p>
448
449 </body>
450 </section>
451 <section>
452 <title>PC Speaker is now a configurable option</title>
453 <body>
454
455 <p>
456 You won't get your normal console beeps (or any response from the PC speaker at
457 all) unless you specifically enable the new PC speaker option
458 (<c>CONFIG_INPUT_PCSPKR</c>):
459 </p>
460
461 <pre caption="Location of PC speaker option">
462 Device Drivers ---&gt;
463 Input device support ---&gt;
464 [*] Misc
465 &lt;*&gt; PC Speaker support
466 </pre>
467
468 <note>
469 By "PC speaker", I am referring to the analogue speaker that beeps once when
470 your system is powering up, I am not referring to normal sound hardware used
471 for playing music, etc.
472 </note>
473
474 </body>
475 </section>
476 <section>
477 <title>New USB Storage block device driver sometimes problematic</title>
478 <body>
479
480 <p>
481 Very recently, a new USB storage device driver has been added to the kernel.
482 At the time of writing, this driver ("ub") is still in its early stages and
483 some users find it to be unreliable. If you have problems accessing your USB
484 hard disk, USB flash disk, USB card reader, or USB digital camera, then you
485 could try reverting to the older SCSI-style driver:
486 </p>
487
488 <pre caption="Disabling ub">
489 Device Drivers ---&gt;
490 Block devices ---&gt;
491 &lt; &gt; Low Performance USB Block driver
492 </pre>
493
494 <note>
495 The older SCSI-style driver (USB Mass Storage support) is enabled by default.
496 It can be found under "Device Drivers --&gt; USB support", but will generally
497 not come into effect while ub is also present.
498 </note>
499
500 </body>
501 </section>
502 <section>
503 <title>usbdevfs renamed to usbfs</title>
504 <body>
505
506 <p>
507 If you have edited your <path>/etc/fstab</path> file to customise the way that
508 the USB device filesystem gets mounted, you may have to modify the filesystem
509 type from <e>usbdevfs</e> to <e>usbfs</e>.
510 </p>
511
512 <note>
513 Recent 2.4 kernels will also allow you to use "usbfs" as well as "usbdevfs", so
514 you aren't breaking any backwards compatibility by doing this.
515 </note>
516
517 </body>
518 </section>
519 <section>
520 <title>Don't renice X</title>
521 <body>
522
523 <p>
524 If you are a desktop 2.4 user, you may have hacked your system into running X
525 at a higher priority, as in some cases it seems to provide better desktop
526 performance.
527 </p>
528
529 <p>
530 There have been many scheduler changes in 2.6 which change this behaviour. If
531 you continue to run X at a higher priority, it will do exactly what it is
532 supposed to (run the <e>display server</e> at a very high priority) and you
533 will notice consequences such as sound stuttering and slow application load
534 times because your CPU is spending too long serving X and only X.
535 </p>
536
537 <p>
538 In Linux 2.6, you no longer need to renice desktop applications to get good
539 interactivity. Please remove your "niceness" hacks!
540 </p>
541
542 </body>
543 </section>
544 <section>
545 <title>X11 config file should now use /dev/input/mice for PS/2 and USB
546 mice</title>
547 <body>
548
549 <p>
550 One of the changes that a default udev configuration introduces is different
551 organisation of the mouse device nodes. Previously, you would have had nodes
552 such as <path>/dev/psaux</path> and <path>/dev/mouse</path>. You will now have
553 nodes such as <path>/dev/input/mouse0</path>, <path>/dev/input/mouse1</path>,
554 and a collective <path>/dev/input/mice</path> node which combines movements
555 from all mice.
556 </p>
557
558 <p>
559 Since the old X configurations typically reference <path>/dev/mouse</path> or
560 <path>/dev/psaux</path> then you may get an error similar to the one shown
561 below when you attempt to start X11:
562 </p>
563
564 <pre caption="Common error when starting X on a udev system for the first time">
565 (EE) xf86OpenSerial: Cannot open device /dev/mouse
566 No such file or directory.
567 (EE) Mouse0: cannot open input device
568 (EE) PreInit failed for input device "Mouse0"
569 No core pointer
570 </pre>
571
572 <p>
573 To correct this, open your X11 config in a text editor, and update the mouse
574 <e>InputDevice</e> section to use the <path>/dev/input/mice</path> device. An
575 example is shown below:
576 </p>
577
578 <pre caption="Opening your X11 config file">
579 # <i>nano -w /etc/X11/xorg.conf</i>
580 </pre>
581
582 <note>
583 If you are still using XFree86, your config file will be
584 <path>/etc/X11/XF86Config</path>
585 </note>
586
587 <pre caption="Sample mouse InputDevice section">
588 Section "InputDevice"
589 Identifier "Mouse0"
590 Driver "mouse"
591 Option "Protocol" "auto"
592 Option "Device" "/dev/input/mice"
593 EndSection
594 </pre>
595
596 <note>
597 If you are using a serial mouse, the new device path will be
598 <path>/dev/tts/0</path> instead of <path>/dev/ttyS0</path>.
599 </note>
600
601 </body>
602 </section>
603 <section>
604 <title>New Serial-ATA (SATA) drivers name the devices differently</title>
605 <body>
606
607 <p>
608 If you used the original Serial ATA drivers under Linux 2.4, you probably
609 observed your SATA devices having names such as <c>/dev/hde</c>.
610 </p>
611
612 <p>
613 Linux 2.6 introduces some new SATA drivers (libata) which are based on the
614 SCSI subsystem. As these drivers are based on SCSI, your SATA disks will now
615 show up as SCSI devices. Your first SATA disk will be named <c>/dev/sda</c>.
616 You will need to update your <c>/etc/fstab</c> file to reflect this, and you
617 will need to bear this in mind when choosing the root/real_root kernel boot
618 parameter later on.
619 </p>
620
621 <note>
622 libata has been backported into recent versions of Linux 2.4, so you may
623 already be familiar with the new device naming.
624 </note>
625
626 </body>
627 </section>
628 <section>
629 <title>bootsplash no longer maintained</title>
630 <body>
631
632 <p>
633 If you used the <c>gentoo-sources-2.4</c> kernel, you may have used the
634 <e>bootsplash</e> functionality in order to provide yourself with a colourful
635 framebuffer console.
636 </p>
637
638 <p>
639 The developer of bootsplash appears to have lost interest in his project, given
640 some design problems. However, Gentoo developer <e>Michal Januszewski</e> is
641 developing a successor, <c>gensplash</c>, which in included in the
642 gentoo-sources-2.6 kernel. You can follow Michal's
643 <uri link="http://dev.gentoo.org/~spock/projects/gensplash/archive/gensplash-in-5-easy-steps.txt">
644 Gensplash in 5 easy steps</uri> document in order to familiarize yourself with
645 how gensplash is operated.
646 </p>
647
648 </body>
649 </section>
650 <section>
651 <title>I2C drivers now included in the kernel</title>
652 <body>
653
654 <p>
655 If you use <c>lm-sensors</c> to monitor system temperatures and power levels,
656 you previously needed to install the <c>i2c</c> package in order to provide
657 hardware support.
658 </p>
659
660 <p>
661 The I2C hardware drivers are now included in the Linux 2.6 kernel, no external
662 i2c package is required. Remember to compile support for your specific I2C
663 devices into the kernel configuration. You will then be able to use
664 <c>lm-sensors</c> as usual.
665 </p>
666
667 </body>
668 </section>
669
670
671 </chapter>
672
673 <chapter id="conf">
674 <title>Configuring, building, and installing the kernel</title>
675 <section>
676 <body>
677
678 <p>
679 As with Linux 2.4, you have two options for managing your new kernel build.
680 </p>
681
682 <ol>
683 <li>
684 The default method is to configure your kernel manually. This may seem
685 daunting but is the preferred way as long as you know your system. If you
686 wish to configure your new kernel manually, please continue on to the <uri
687 link="#manual">next chapter</uri>.
688 </li>
689 <li>
690 The alternative option is to use our <c>genkernel</c> utility to
691 automatically configure, compile, and install a kernel for you. If you wish
692 to use <c>genkernel</c> then skip over the next chapter and proceed with
693 <uri link="#genkernel">using genkernel</uri>.
694 </li>
695 </ol>
696
697 </body>
698 </section>
699 </chapter>
700
701 <chapter id="manual">
702 <title>Default: Manual configuration</title>
703 <section>
704 <title>Configuring the kernel</title>
705 <body>
706
707 <p>
708 We'll now get on with configuring the kernel. Open menuconfig in the usual way:
709 </p>
710
711 <pre caption="Invoking menuconfig">
712 # <i>cd /usr/src/linux</i>
713 # <i>make menuconfig</i>
714 </pre>
715
716 <p>
717 You will probably be familiar with using menuconfig from configuring 2.4
718 kernels. Fortunately, the front end has barely changed at all, but you will
719 observe much better organisation of kernel options, plus <e>many</e> new
720 options that weren't present in 2.4.
721 </p>
722
723 <p>
724 Be sure to enable the following important kernel options:
725 </p>
726
727 <pre caption="Required kernel options">
728 File systems ---&gt;
729 Pseudo Filesystems ---&gt;
730 [*] /proc file system support
731 [*] Virtual memory file system support (former shm fs)
732
733 <comment>(the following are required for udev):</comment>
734 General setup ---&gt;
735 [*] Support for hot-pluggable devices
736
737 Device Drivers ---&gt;
738 Block devices ---&gt;
739 &lt;*&gt; RAM disk support
740
741 <comment>(the following are required for ALSA):</comment>
742 Device Drivers ---&gt;
743 Sound ---&gt;
744 &lt;*&gt; Sound card support
745 Advanced Linux Sound Architecture ---&gt;
746 &lt;M&gt; Advanced Linux Sound Architecture
747 &lt;M&gt; Sequencer support
748 &lt;M&gt; OSS Mixer API
749 [*] OSS Sequencer API
750 <comment> (and dont forget to select your soundcard from the submenus!)</comment>
751
752 <comment>(the following are required if you use LVM for disk management):</comment>
753 Device Drivers ---&gt;
754 Multi-device support (RAID and LVM) ---&gt;
755 [*] Multiple devices driver support (RAID and LVM)
756 &lt;*&gt; Device mapper support
757 </pre>
758
759 <warn>
760 Previously you may have included support for the <path>/dev</path> file system
761 (now marked OBSOLETE). Do not enable devfs support. We have installed udev,
762 which we will be using instead of devfs from now on.
763 </warn>
764
765 <p>
766 Also, remember to enable support for the filesystems that you use, and the
767 hardware present in your system. Be sure to enable support for the IDE
768 controller on your motherboard if you wish to benefit from fast DMA disk
769 access. Refer to the <uri
770 link="/doc/en/handbook/handbook-x86.xml?part=1&amp;chap=7">Configuring the
771 Kernel</uri> section of the <uri link="/doc/en/handbook/index.xml">Gentoo
772 Handbook</uri> for additional guidance here.
773 </p>
774
775 </body>
776 </section>
777 <section>
778 <title>Building the kernel</title>
779 <body>
780
781 <p>
782 Now that we have configured the kernel, we can start the compilation process:
783 </p>
784
785 <pre caption="Compiling the kernel source">
786 # <i>make &amp;&amp; make modules_install</i>
787 </pre>
788
789 <note>
790 You may recall having to run <c>make dep</c> with Linux 2.4 sources. This is no
791 longer required.
792 </note>
793
794 <p>
795 Wait for the kernel compilation to complete (and observe the much more readable
796 compilation output).
797 </p>
798
799 </body>
800 </section>
801 <section>
802 <title>Installing the kernel</title>
803 <body>
804
805 <p>
806 The next step is mounting your <path>/boot</path> partition and copying the
807 kernel image over. You must then update your bootloader config manually.
808 </p>
809
810 <pre caption="Installing the kernel">
811 # <i>mount /boot</i>
812 # <i>cp arch/i386/boot/bzImage /boot/bzImage-2.6.10-gentoo-r4</i>
813 # <i>cp System.map /boot/System.map-2.6.10-gentoo-r4</i>
814 </pre>
815
816 <p>
817 Note that the above instructions are examples only, you should follow your
818 usual procedure of updating kernels by following the instructions in the <uri
819 link="/doc/en/handbook/index.xml">Gentoo Handbook</uri> (see the <uri
820 link="/doc/en/handbook/handbook-x86.xml?part=1&amp;chap=7">Configuring the
821 Kernel</uri> chapter).
822 </p>
823
824 <p>
825 When updating your bootloader config, do not remove the old entry pointing at
826 your 2.4 kernel. This way, you will easily be able to switch between the two if
827 something is not working.
828 </p>
829
830 <p>
831 Now continue onto the <uri link="#modules">Module Configuration</uri> section.
832 </p>
833
834 </body>
835 </section>
836 </chapter>
837
838 <chapter id="genkernel">
839 <title>Alternative: Using genkernel</title>
840 <section>
841 <body>
842
843 <p>
844 If you prefer to use genkernel instead of manually configuring your kernel, you
845 will be happy to hear that using genkernel to produce 2.6 kernels is very
846 similar to the process you performed when producing your previous 2.4 kernel.
847 </p>
848
849 <p>
850 You should invoke genkernel as shown below:
851 </p>
852
853 <pre caption="Invoking genkernel with some common arguments">
854 # <i>genkernel --udev --menuconfig --bootloader=grub all</i>
855 </pre>
856
857 <p>
858 In the above example, we also take advantage of genkernel features to open
859 menuconfig to allow you to customise the kernel configuration (if you wish),
860 and to update the grub bootloader configuration after compilation.
861 </p>
862
863 <p>
864 You should choose genkernel arguments that suit you, but do not forget to
865 include the <c>--udev</c> argument! Refer to the <uri
866 link="/doc/en/genkernel.xml">Gentoo Linux Genkernel Guide</uri> and the <uri
867 link="/doc/en/handbook/handbook-x86.xml?part=1&amp;chap=7">Configuring the
868 Kernel</uri> chapter of the <uri link="/doc/en/handbook/index.xml">Gentoo
869 Handbook</uri> for additional information.
870 </p>
871
872 <p>
873 If you choose to update your bootloader config yourself, then you must
874 remember to include the <c>udev</c> kernel parameter. A sample <e>grub</e>
875 config section is shown below, but remember to adjust the <e>real_root</e>
876 parameter for your system.
877 </p>
878
879 <pre caption="Sample GRUB config for genkernel + udev">
880 title=Gentoo Linux (2.6 kernel)
881 root (hd0,0)
882 kernel /kernel-2.6.10-gentoo-r4 <i>udev</i> root=/dev/ram0 init=/linuxrc ramdisk=8192 real_root=/dev/hda3
883 initrd /initrd-2.6.10-gentoo-r4
884 </pre>
885
886 </body>
887 </section>
888 </chapter>
889
890 <chapter id="modules">
891 <title>Module Configuration</title>
892
893 <section>
894 <title>Installing external modules</title>
895 <body>
896
897 <p>
898 Many users will additionally rely on kernel modules that are built outside of
899 the kernel tree. Common examples are the binary ATI and Nvidia graphics
900 drivers. You now need to install those modules, which will compile against the
901 2.6 sources found at <path>/usr/src/linux</path>. This is the usual case of
902 <c>emerge packagename</c> for all the external modules you are used to using
903 with 2.4.
904 </p>
905
906 <p>
907 Refer again to the <uri
908 link="/doc/en/handbook/handbook-x86.xml?part=1&amp;chap=7">Configuring the
909 Kernel</uri> chapter of the <uri link="/doc/en/handbook/index.xml">Gentoo
910 Handbook</uri> for more info.
911 </p>
912
913 </body>
914 </section>
915 <section>
916 <title>Autoloading modules</title>
917 <body>
918
919 <p>
920 You may have decided to compile some kernel components as modules (as opposed
921 to compiled directly into the kernel) and would like to have them autoloaded on
922 bootup like you did with 2.4. Also, if you installed any external modules from
923 the portage tree (as described above) you will probably want to autoload them
924 too.
925 </p>
926
927 <p>
928 You can achieve this similarly as to how you did with 2.4. Simply open up the
929 file <path>/etc/modules.autoload.d/kernel-2.6</path> in a text editor and list
930 the names of the modules you would like autoloaded.
931 </p>
932
933 <pre caption="Opening the module autoload list in nano">
934 # <i>nano -w /etc/modules.autoload.d/kernel-2.6</i>
935 </pre>
936
937 <pre caption="Sample autoload list to load the 3c59x and nvidia modules">
938 # /etc/modules.autoload.d/kernel-2.6: kernel modules to load when system boots.
939 #
940 # Note that this file is for 2.6 kernels.
941 #
942 # Add the names of modules that you'd like to load when the system
943 # starts into this file, one per line. Comments begin with # and
944 # are ignored. Read man modules.autoload for additional details.
945
946 3c59x
947 nvidia
948 </pre>
949
950 </body>
951 </section>
952 </chapter>
953
954 <chapter>
955 <title>LVM to LVM2 migration</title>
956 <section>
957 <title>Upgrading to LVM2 tools</title>
958 <body>
959
960 <note>
961 If you do not use LVM to manage your disk storage, you can safely skip
962 this chapter and skip onto the next.
963 </note>
964
965 <p>
966 Fortunately, upgrading from the LVM1 user tools to the LVM2 versions is very
967 simple:
968 </p>
969
970 <pre caption="Upgrading user-tools from LVM1 to LVM2">
971 # <i>emerge --unmerge lvm-user</i>
972 # <i>emerge lvm2</i>
973 </pre>
974
975 <note>
976 The LVM2 tools are fully backwards-compatible with LVM1. Your disk data will
977 not be touched. You are not breaking any backwards-compatibility by doing
978 this, you will continue to be able to boot 2.4 as usual.
979 </note>
980
981 </body>
982 </section>
983 </chapter>
984
985 <chapter>
986 <title>Booting into Linux 2.6</title>
987 <section>
988 <body>
989
990 <p>
991 It's now time to boot into Linux 2.6. Close all applications and reboot:
992 </p>
993
994 <pre caption="Rebooting">
995 # <i>umount /boot</i>
996 # <i>reboot</i>
997 </pre>
998
999 <p>
1000 When you reboot, if you followed this document correctly so far, you will have
1001 the option of either loading Linux 2.4 or Linux 2.6 from your bootloader.
1002 Choose Linux 2.6.
1003 </p>
1004
1005 <p>
1006 Once the system has booted, check that things are working. If you made a
1007 mistake in the kernel configuration, don't worry, you can skip back to the
1008 <uri link="#conf">Configuring, building, and installing the kernel</uri>
1009 section, make your change, recompile and install new kernel image, reboot, and
1010 try again!
1011 </p>
1012
1013 </body>
1014 </section>
1015 <section>
1016 <title>Configuring and unmuting ALSA</title>
1017 <body>
1018
1019 <p>
1020 We will now complete the ALSA configuration and unmute the audio channels. The
1021 ALSA packages provide a useful utility to make this process relatively simple:
1022 </p>
1023
1024 <pre caption="Invoking the automatic ALSA configuration utility">
1025 # <i>alsaconf</i>
1026 </pre>
1027
1028 <p>
1029 The process is straightforward: allow the <e>/etc/modules.d/alsa</e> file to
1030 be automatically updated, and then allow ALSA to be reloaded. alsaconf will
1031 then terminate, however you will need to run it multiple times if you have
1032 multiple sound devices installed in your system.
1033 </p>
1034
1035 <p>
1036 You should now add <c>alsasound</c> to your boot runlevel, so that volumes
1037 will be saved on shutdown and restored on bootup:
1038 </p>
1039
1040 <pre caption="Adding alsasound to the boot runlevel">
1041 # <i>rc-update add alsasound boot</i>
1042 </pre>
1043
1044 <note>
1045 The <c>alsaconf</c> utility chooses initial volume levels for your sound
1046 devices. If these are inappropriate, you can modify them at any time with the
1047 <c>alsamixer</c> utility.
1048 </note>
1049
1050 </body>
1051 </section>
1052 <section>
1053 <title>Any immediate problems?</title>
1054 <body>
1055
1056 <p>
1057 At this stage you should refer back to the <uri link="#pitfalls">Known
1058 pitfalls with Linux 2.6 migration</uri> section which may be helpful with any
1059 issues you encounter immediately.
1060 </p>
1061
1062 </body>
1063 </section>
1064 </chapter>
1065
1066 <chapter>
1067 <title>Header files and NPTL</title>
1068 <section>
1069 <body>
1070
1071 <p>
1072 By now you are running Linux 2.6 and hopefully have all issues ironed out. You
1073 should now update your Linux kernel header files and re-merge glibc so that
1074 userspace applications can take advantage of new Linux 2.6 features.
1075 </p>
1076
1077 <pre caption="Updating to linux26-headers">
1078 # <i>emerge --unmerge linux-headers</i>
1079 # <i>emerge linux26-headers</i>
1080 </pre>
1081
1082 <p>
1083 After updating your headers package, you should generally re-merge glibc.
1084 There is a new feature here that you may be interested in - NPTL. NPTL is a new
1085 threading model present in Linux 2.6, which features much quicker thread create
1086 and destroy times. This won't make much of a difference to most systems, but
1087 you may wish to enable it during this migration process! To enable NPTL, edit
1088 <path>/etc/make.conf</path>, adding <e>nptl</e> to your USE variable.
1089 </p>
1090
1091 <warn>
1092 With the current stable glibc ebuilds, you will be unable to boot a 2.4 kernel
1093 after compiling glibc with USE="nptl". Be warned, be careful!
1094 </warn>
1095
1096 <p>
1097 Now re-merge glibc (you should do this even if you did not choose to enable
1098 NPTL).
1099 </p>
1100
1101 <pre caption="Reinstalling glibc against the new kernel headers">
1102 # <i>emerge -a glibc</i>
1103 </pre>
1104
1105 <p>
1106 If you enabled NPTL, existing binaries will not use it until they are
1107 recompiled. However, any binaries compiled from this point onwards <e>will</e>
1108 use NPTL. You may wish to recompile all binaries now, e.g.:
1109 </p>
1110
1111 <pre caption="Recompiling all packages on the system">
1112 # <i>emerge -e world</i>
1113 </pre>
1114
1115 <p>
1116 Alternatively, you can just let your system "naturally" convert itself to NPTL
1117 as you update to newer versions of packages when they are released.
1118 </p>
1119
1120 </body>
1121 </section>
1122 </chapter>
1123
1124 <chapter>
1125 <title>Closing remarks</title>
1126 <section>
1127 <title>Problems?</title>
1128 <body>
1129
1130 <p>
1131 With the incredible amount of work that went into Linux 2.6, it is sometimes
1132 inevitable that things which used to work fine, no longer function as expected.
1133 </p>
1134
1135 <p>
1136 If you have any problems with your 2.6 kernel, and you can confirm that this
1137 problem does not exist with Linux 2.4, then please open a bug with us on our
1138 <uri link="http://bugs.gentoo.org">Bugzilla</uri>. We will investigate the
1139 issue, and if we find that it is a problem in the mainline kernel, we may then
1140 ask you to file a report at the central kernel bugzilla.
1141 </p>
1142
1143 </body>
1144 </section>
1145 <section>
1146 <title>Conclusion</title>
1147 <body>
1148
1149 <p>
1150 Hopefully you have just completed a smooth migration and you are enjoying the
1151 benefits which Linux 2.6 brings over 2.4.
1152 </p>
1153
1154 <p>
1155 I would like to say a word of thanks to the many users who effectively
1156 'tested' this document while it was in its early stages, and provided feedback
1157 about how the migration process went. Sorry that I did not reply to all the
1158 emails (there were a lot!), but I did read every one, and refined this
1159 document where appropriate. Enjoy your 2.6-enhanced systems :)
1160 </p>
1161
1162 </body>
1163 </section>
1164 <section>
1165 <title>Removing Linux 2.4 from your system</title>
1166 <body>
1167
1168 <p>
1169 After you have been running 2.6 for a while, you may decide that you no longer
1170 have any requirement to be able to use Linux 2.4. The steps you can take to
1171 clean up your system are detailed below. <e>Only follow the procedure in this
1172 section if you are sure that you don't want/need to use 2.4 again!</e>
1173 </p>
1174
1175 <p>
1176 The 2.4 kernel source code can be removed, using the emerge utility as usual.
1177 For example, assuming you have 2.4 versions of vanilla-sources and
1178 gentoo-sources installed, you could use the following command to remove them
1179 while keeping the 2.6 versions intact:
1180 </p>
1181
1182 <pre caption="Example: Removing Linux 2.4 sources">
1183 # <i>emerge --unmerge =vanilla-sources-2.4.* =gentoo-sources-2.4.*</i>
1184 </pre>
1185
1186 <p>
1187 Portage will not completely clean out your 2.4 kernel source installations,
1188 because some temporary files are created during compilation. It is safe to
1189 remove these remnants with the following command:
1190 </p>
1191
1192 <pre caption="Removing remaining temporary files">
1193 # <i>rm -rf /usr/src/linux-2.4.*</i>
1194 </pre>
1195
1196 <p>
1197 You can additionally remove modules and information files relating to your
1198 old 2.4 kernel installations, as these are no longer needed.
1199 </p>
1200
1201 <pre caption="Removing previously-installed 2.4 modules">
1202 # <i>rm -rf /lib/modules/2.4.*</i>
1203 </pre>
1204
1205 <p>
1206 The 2.4 kernel binaries you used to boot from can also be safely removed.
1207 You should mount your <c>/boot</c> partition, and remove those images. You
1208 should also update your bootloader configuration so that it no longer
1209 references these deleted kernel images.
1210 </p>
1211
1212 <p>
1213 Some Linux 2.4 users will have previously installed the <c>alsa-driver</c>
1214 package to benefit from the new audio capabilities included in Linux 2.6. If
1215 you were one of these users, and you followed the advice given earlier in this
1216 document about building ALSA with the 2.6 kernel sources (as opposed to using
1217 the <c>alsa-driver</c> package), then you can safely remove this to prevent
1218 future conflicts.
1219 </p>
1220
1221 <p>
1222 Additionally, <c>lm-sensors</c> users will have previously used the <c>i2c</c>
1223 package to provide the hardware drivers. As already mentioned, I2C drivers are
1224 now included in the kernel, so this package can also be removed in order to
1225 prevent future conflicts.
1226 </p>
1227
1228 <p>
1229 The devfs management daemon, <c>devfsd</c>, can also safely be removed, now
1230 that we are using <c>udev</c> for device management.
1231 </p>
1232
1233 <pre caption="Removing alsa-driver, i2c, and devfsd">
1234 # <i>emerge --unmerge alsa-driver i2c devfsd</i>
1235 </pre>
1236
1237 <p>
1238 If you are LVM2 user, you may wish to convert your data into the LVM2 data
1239 format in order to benefit from the advantages which LVM2 provides.
1240 However, this operation will prevent you from ever accessing your LVM data
1241 from a 2.4 kernel. If you want to continue with the conversion (this is totally
1242 optional!), then you should examine the <c>vgconvert</c> man page for
1243 instructions on how to carry this out. An example is shown below, where
1244 <c>main</c> is the volume group name.
1245 </p>
1246
1247 <pre caption="Converting a LVM1 volume to LVM2 format">
1248 # <i>vgconvert -M2 main</i>
1249 </pre>
1250
1251 </body>
1252 </section>
1253 </chapter>
1254 </guide>

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