/[gentoo]/xml/htdocs/doc/en/migration-to-2.6.xml
Gentoo

Contents of /xml/htdocs/doc/en/migration-to-2.6.xml

Parent Directory Parent Directory | Revision Log Revision Log


Revision 1.28 - (show annotations) (download) (as text)
Wed Mar 16 07:41:36 2011 UTC (3 years, 7 months ago) by nightmorph
Branch: MAIN
Changes since 1.27: +8 -5 lines
File MIME type: application/xml
use different bind mount, bug 253681

1 <?xml version='1.0' encoding="UTF-8"?>
2 <!DOCTYPE guide SYSTEM "/dtd/guide.dtd">
3 <!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/migration-to-2.6.xml,v 1.27 2008/03/06 05:59:25 nightmorph Exp $ -->
4
5 <guide>
6 <title>The complete Gentoo Linux 2.6 migration guide</title>
7
8 <author title="Author">
9 <mail link="dsd@gentoo.org">Daniel Drake</mail>
10 </author>
11 <author title="Contributor">
12 <mail link="sergey_zlodey@mail.ru">Sergey Galkin</mail>
13 </author>
14 <author title="Contributor">
15 <mail link="svyatogor@gentoo.org">Sergey Kuleshov</mail>
16 </author>
17 <author title="Editor">
18 <mail link="neysx@gentoo.org">Xavier Neys</mail>
19 </author>
20 <author title="Editor">
21 <mail link="bennyc@gentoo.org">Benny Chuang</mail>
22 </author>
23 <author title="Editor">
24 <mail link="nightmorph"/>
25 </author>
26
27 <abstract>
28 This document will aid you in the process of migrating from Linux 2.4 to Linux
29 2.6, devfs to udev, OSS to ALSA, and LVM to LVM2.
30 </abstract>
31
32 <version>1</version>
33 <date>2011-03-16</date>
34
35 <chapter>
36 <title>Introduction</title>
37 <section>
38 <title>What is new in Linux 2.6?</title>
39 <body>
40
41 <p>
42 That is not an 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 architecturally
44 quite different from its 2.4 counterpart. Some of the major changes are listed
45 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.codemonkey.org.uk/docs/post-halloween-2.6.txt">The
70 post-halloween document</uri> - but do bear in mind that this is somewhat
71 outdated now.
72 </p>
73
74 </body>
75 </section>
76 <section>
77 <title>Gentoo and 2.6</title>
78 <body>
79
80 <p>
81 From the 2005.0 release of Gentoo Linux, the default kernel is the latest 2.6
82 series kernel. The default profile of the system is picked up from
83 <path>/etc/make.profile</path> which on 2005.0 or above would be a symlink to
84 <path>/usr/portage/profiles/default-linux/x86/2005.0</path> under which various
85 important settings are taken care of.
86 </p>
87
88 <p>
89 If you are using a 2.4 profile, please change it to one that supports a 2.6
90 kernel by doing the following.
91 </p>
92
93 <pre caption="Changing your profile">
94 # <i>rm -f /etc/make.profile</i>
95 # <i>ln -snf /usr/portage/profiles/default-linux/x86/2005.1 /etc/make.profile</i>
96 </pre>
97
98 </body>
99 </section>
100 <section>
101 <title>What is udev?</title>
102 <body>
103
104 <p>
105 In the past, Gentoo has instructed users to use <e>devfs</e> for managing the
106 <path>/dev</path> directory, which contains a series of device interfaces to
107 allow system applications to communicate with hardware (through the kernel).
108 </p>
109
110 <p>
111 <e>devfs</e>, whilst a good concept, has some internal problems, and has been
112 completely removed from the main stable tree as of 2.6.13.
113 </p>
114
115 <p>
116 <e>udev</e> is the new way of managing device nodes. It addresses issues with
117 previous device managers, and also attempts to solve some other problems.
118 </p>
119
120 <p>
121 The above may not mean much to you, but fear not, the hard working Gentoo
122 developers have put effort into making the migration from devfs very easy.
123 Please read the <uri link="/doc/en/udev-guide.xml">Gentoo udev Guide</uri> for
124 more information regarding the same.
125 </p>
126
127 </body>
128 </section>
129 <section>
130 <title>What is ALSA?</title>
131 <body>
132
133 <p>
134 With Linux 2.4, chances are that you used OSS (open sound system) drivers to
135 power your sound card. OSS has been replaced by a newer and better set of sound
136 drivers: ALSA.
137 </p>
138
139 <p>
140 ALSA, the Advanced Linux Sound Architecture, is a new set of sound drivers with
141 a new and improved API, present in the Linux 2.6 kernel. It is backwards
142 compatible with OSS applications, provided that you select the right kernel
143 configuration options!
144 </p>
145
146 <note>
147 If you do not have any sound/audio hardware, you can safely skip over any
148 ALSA-related instructions in this document.
149 </note>
150
151 </body>
152 </section>
153 <section>
154 <title>What is LVM?</title>
155 <body>
156
157 <p>
158 <e>Logical Volume Management</e> (LVM) exists as set of tools allowing you to
159 manage your disk storage in a very flexible manner. Amongst other things, it
160 allows powerful control over partitions (e.g. resizing without reboot), and
161 makes operations like device changes relatively simple. LVM acts as an
162 alternative to standard partition-based disk management.
163 </p>
164
165 <p>
166 LVM support has historically been implemented in Linux 2.4. Linux 2.6 features
167 a new version of LVM, named <e>LVM2</e>. The migration process requires you to
168 install new versions of the user-level tools (covered later in this document)
169 but will leave your data intact!
170 </p>
171
172 <p>
173 <e>If you do not currently use LVM for data-storage management, then LVM2
174 migration does not apply to you.</e> If this is the case, you can safely ignore
175 any parts of this document referencing LVM/LVM2. Upgrading to Linux 2.6 does
176 <e>not</e> require you to store your data on LVM partitions - you can keep your
177 data in the standard partition-format as it always has been.
178 </p>
179
180 <p>
181 If you are not a LVM user, but you think LVM2 sounds useful for you, you can
182 convert your disks to this format at a later date, by following the <uri
183 link="/doc/en/lvm2.xml">Gentoo LVM2 Installation Guide</uri>. For now, let us
184 just concentrate on getting a smooth 2.6 migration underway.
185 </p>
186
187 </body>
188 </section>
189 </chapter>
190
191 <chapter>
192 <title>Preparation</title>
193 <section>
194 <title>Get your system up-to-date</title>
195 <body>
196
197 <p>
198 Some of the changes brought in with Linux 2.6 also required some changes in the
199 base system applications. Before continuing, you should ensure that your system
200 is relatively up-to-date, and to be perfectly sure, you should update all world
201 and system packages where updates are available.
202 </p>
203
204 <p>
205 In particular, make sure you have the latest stable versions of the following
206 packages:
207 </p>
208
209 <ul>
210 <li><c>sys-apps/baselayout</c></li>
211 <li><c>sys-apps/util-linux</c></li>
212 <li>
213 <c>sys-kernel/genkernel</c> (only if you wish to use genkernel as opposed
214 to manual configuration)
215 </li>
216 </ul>
217
218 <pre caption="Updating all world packages">
219 # <i>emerge --sync</i>
220 # <i>emerge -ua world</i>
221 </pre>
222
223 </body>
224 </section>
225 <section>
226 <title>modutils vs module-init-tools</title>
227 <body>
228
229 <p>
230 <c>sys-apps/modutils</c> is the package that provides tools such as
231 <c>modprobe</c>, <c>rmmod</c> and <c>insmod</c> for Linux 2.4.
232 </p>
233
234 <p>
235 Linux 2.6 introduces a new module format, and therefore requires new tools for
236 handling modules. These are bundled up into the
237 <c>sys-apps/module-init-tools</c> package.
238 </p>
239
240 <p>
241 You should now remove modutils and install module-init-tools:
242 </p>
243
244 <pre caption="Switching from modutils to module-init-tools">
245 # <i>emerge --unmerge sys-apps/modutils</i>
246 # <i>emerge module-init-tools</i>
247 </pre>
248
249 <note>
250 Don't worry - even though you have just unmerged modutils, module-init-tools
251 provides backwards compatibility for Linux 2.4, so you will still be able to
252 boot into Linux 2.4 and handle modules for that kernel.
253 </note>
254
255 <note>
256 For the above reason, module-init-tools might already be installed and working
257 with your existing Linux 2.4 kernel. In this case, you don't need to worry
258 about this stage - your system is already ready to deal with Linux 2.6 modules.
259 </note>
260
261 </body>
262 </section>
263 <section>
264 <title>Installing udev</title>
265 <body>
266
267 <p>
268 There is no configuration involved here. Simply use <c>emerge</c> to install
269 udev:
270 </p>
271
272 <pre caption="Installing udev">
273 # <i>emerge -a udev</i>
274 </pre>
275
276 <p>
277 You should now read the <uri link="/doc/en/udev-guide.xml">Gentoo udev
278 Guide</uri> to get a more complete idea about the differences between udev and
279 devfs.
280 </p>
281
282 </body>
283 </section>
284 <section>
285 <title>Checking for essential device nodes</title>
286 <body>
287
288 <p>
289 When the system boots up, the system requires some essential device nodes. As
290 udev is not included in the kernel, it is not activated immediately. To work
291 around this, you must ensure that you have some essential device nodes on your
292 disk.
293 </p>
294
295 <p>
296 Our installation stage files will have created the required devices during the
297 initial installation. However, some users have reported that this is not the
298 case. We will use this opportunity to check that the device files exist, and
299 create them if they do not.
300 </p>
301
302 <p>
303 As your existing device manager will be mounted at <path>/dev</path>, we cannot
304 access it directly. So we will bind-mount your root partition to another
305 location and access the <path>/dev</path> directory from there.
306 </p>
307
308 <pre caption="Bind-mounting your root partition and listing static devices">
309 # <i>mkdir -p /mnt/temp</i>
310 # <i>mount --rbind / /mnt/temp</i>
311 # <i>cd /mnt/temp/dev</i>
312 # <i>ls -l console null</i>
313 </pre>
314
315 <p>
316 If the above <e>ls</e> command reported that either <c>console</c> or
317 <c>null</c> do not exist, then you must create them yourself, as shown below.
318 </p>
319
320 <pre caption="Creating the missing console and null nodes">
321 # <i>mknod -m 660 console c 5 1</i>
322 # <i>mknod -m 660 null c 1 3</i>
323 </pre>
324
325 <p>
326 You should now unmount your bind-mounted root partition, even if you did not
327 have to create those devices:
328 </p>
329
330 <pre caption="Unmounting the bind-mounted root">
331 # <i>cd</i>
332 # <i>umount /mnt/temp</i>
333 # <i>rmdir /mnt/temp</i>
334 </pre>
335
336 </body>
337 </section>
338 <section>
339 <title>Installing ALSA utilities</title>
340 <body>
341
342 <p>
343 ALSA requires you to have some packages installed, so that applications can use
344 the ALSA API. These packages will also allow you to control the mixer and
345 volume levels. Install the required utilities as follows:
346 </p>
347
348 <pre caption="Installing ALSA utilities and libraries">
349 # <i>emerge -a alsa-lib alsa-utils alsa-tools alsa-headers alsa-oss</i>
350 </pre>
351
352 </body>
353 </section>
354 </chapter>
355
356 <chapter>
357 <title>Installing the Linux 2.6 sources</title>
358
359 <section>
360 <title>Choosing and installing a kernel</title>
361 <body>
362
363 <p>
364 The first thing you need to do is install sources of a 2.6 kernel of your
365 choice. The two Gentoo-supported 2.6 kernels are currently
366 <e>gentoo-sources</e> (for desktops) and <e>hardened-sources</e> (for
367 servers). There are others available, see the <uri
368 link="/doc/en/gentoo-kernel.xml">Gentoo Linux Kernel Guide</uri> for more
369 choices.
370 </p>
371
372 <p>
373 In this guide, we'll use <c>gentoo-sources</c> as an example. Install your
374 chosen set of kernel sources using the <c>emerge</c> utility:
375 </p>
376
377 <pre caption="Installing gentoo-sources">
378 # <i>emerge -a gentoo-sources</i>
379 These are the packages that I would merge, in order:
380 Calculating dependencies ...done!
381 [ebuild NS ] sys-kernel/gentoo-sources-2.6.10-r4
382
383 Do you want me to merge these packages? [Yes/No] <i>y</i>
384 </pre>
385
386 <p>
387 When performing the above <c>emerge</c> command, if you find that it wants to
388 install a 2.4 version of gentoo-sources (e.g. <c>gentoo-sources-2.4.26</c>),
389 then it means that the profile you are using is not designed for Linux 2.6
390 users. Please follow the <uri link="/doc/en/gentoo-upgrading.xml">Gentoo
391 Upgrading Document</uri> to switch to a 2.6-based profile, and retry installing
392 2.6 kernel sources.
393 </p>
394
395 </body>
396 </section>
397 <section>
398 <title>Updating the /usr/src/linux symbolic link</title>
399 <body>
400
401 <p>
402 Various components of the Gentoo utilities rely on <path>/usr/src/linux</path>
403 being a symbolic link to the kernel sources that you are running (or wish to
404 compile against).
405 </p>
406
407 <p>
408 We will now update our <path>/usr/src/linux</path> link to point at the kernel
409 sources we just installed. Continuing our example:
410 </p>
411
412 <pre caption="Updating the /usr/src/linux softlink">
413 # <i>cd /usr/src</i>
414 # <i>ln -sfn linux-2.6.10-gentoo-r4 linux</i>
415 </pre>
416
417 </body>
418 </section>
419 </chapter>
420
421 <chapter id="pitfalls">
422 <title>Known pitfalls with Linux 2.6 migration</title>
423 <section>
424 <body>
425
426 <p>
427 Before we get stuck into configuring the kernel, I'll attempt to detail the
428 most common errors that people make when migrating to Linux 2.6, as some of
429 these points will influence the way you configure the new kernel.
430 </p>
431
432 <note>
433 Not all of these points are relevant at this stage, but I will detail them all
434 here in one place, and you can refer back at your leisure.
435 </note>
436
437 </body>
438 </section>
439 <section>
440 <title>Don't use "make oldconfig" with a 2.4 .config</title>
441 <body>
442
443 <note>
444 If you don't understand what this means, don't worry, you won't make this
445 mistake if you follow the rest of this guide correctly.
446 </note>
447
448 <p>
449 You'll be asked many many questions, since there have been a large amount of
450 changes. Many people who do try a <c>make oldconfig</c> from a 2.4 config end
451 up creating an unworkable kernel (e.g. no output on-screen, no input from
452 keyboard, etc). Please save yourself the trouble, and use the traditional
453 <c>menuconfig</c> configuration method just this once.
454 </p>
455
456 </body>
457 </section>
458 <section>
459 <title>Don't use ide-scsi for CD/DVD writing</title>
460 <body>
461
462 <p>
463 In Linux 2.4, the only way to achieve good CD/DVD writing results was to enable
464 the (rather ugly) <c>ide-scsi</c> emulation. Thankfully, the IDE layer in Linux
465 2.6 has been extended to support CD/DVD writers much better.
466 </p>
467
468 <p>
469 You don't need to enable any extra options to support CD writing. Just be sure
470 <e>not</e> to enable <c>ide-scsi</c> as you used to.
471 </p>
472
473 </body>
474 </section>
475 <section>
476 <title>PC Speaker is now a configurable option</title>
477 <body>
478
479 <p>
480 You won't get your normal console beeps (or any response from the PC speaker at
481 all) unless you specifically enable the new PC speaker option
482 (<c>CONFIG_INPUT_PCSPKR</c>):
483 </p>
484
485 <pre caption="Location of PC speaker option">
486 Device Drivers ---&gt;
487 Input device support ---&gt;
488 [*] Misc
489 &lt;*&gt; PC Speaker support
490 </pre>
491
492 <note>
493 By "PC speaker", I am referring to the analogue speaker that beeps once when
494 your system is powering up, I am not referring to normal sound hardware used
495 for playing music, etc.
496 </note>
497
498 </body>
499 </section>
500 <section>
501 <title>New USB Storage block device driver sometimes problematic</title>
502 <body>
503
504 <p>
505 Very recently, a new USB storage device driver has been added to the kernel.
506 At the time of writing, this driver ("ub") is still in its early stages and
507 some users find it to be unreliable. If you have problems accessing your USB
508 hard disk, USB flash disk, USB card reader, or USB digital camera, then you
509 could try reverting to the older SCSI-style driver:
510 </p>
511
512 <pre caption="Disabling ub">
513 Device Drivers ---&gt;
514 Block devices ---&gt;
515 &lt; &gt; Low Performance USB Block driver
516 </pre>
517
518 <note>
519 The older SCSI-style driver (USB Mass Storage support) is enabled by default.
520 It can be found under "Device Drivers --&gt; USB support", but will generally
521 not come into effect while ub is also present.
522 </note>
523
524 </body>
525 </section>
526 <section>
527 <title>usbdevfs renamed to usbfs</title>
528 <body>
529
530 <p>
531 If you have edited your <path>/etc/fstab</path> file to customise the way that
532 the USB device filesystem gets mounted, you may have to modify the filesystem
533 type from <e>usbdevfs</e> to <e>usbfs</e>.
534 </p>
535
536 <note>
537 Recent 2.4 kernels will also allow you to use "usbfs" as well as "usbdevfs", so
538 you are not breaking any backwards compatibility by doing this.
539 </note>
540
541 </body>
542 </section>
543 <section>
544 <title>Don't renice X</title>
545 <body>
546
547 <p>
548 If you are a desktop 2.4 user, you may have hacked your system into running X
549 at a higher priority, as in some cases it seems to provide better desktop
550 performance.
551 </p>
552
553 <p>
554 There have been many scheduler changes in 2.6 which change this behaviour. If
555 you continue to run X at a higher priority, it will do exactly what it is
556 supposed to (run the <e>display server</e> at a very high priority) and you
557 will notice consequences such as sound stuttering and slow application load
558 times because your CPU is spending too long serving X and only X.
559 </p>
560
561 <p>
562 In Linux 2.6, you no longer need to renice desktop applications to get good
563 interactivity. Please remove your "niceness" hacks!
564 </p>
565
566 </body>
567 </section>
568 <section>
569 <title>X11 config file should now use /dev/input/mice for PS/2 and USB mice</title>
570 <body>
571
572 <p>
573 One of the changes that a default udev configuration introduces is different
574 organisation of the mouse device nodes. Previously, you would have had nodes
575 such as <path>/dev/psaux</path> and <path>/dev/mouse</path>. You will now have
576 nodes such as <path>/dev/input/mouse0</path>, <path>/dev/input/mouse1</path>,
577 and a collective <path>/dev/input/mice</path> node which combines movements
578 from all mice.
579 </p>
580
581 <p>
582 Since the old X configurations typically reference <path>/dev/mouse</path> or
583 <path>/dev/psaux</path> then you may get an error similar to the one shown
584 below when you attempt to start X11:
585 </p>
586
587 <pre caption="Common error when starting X on a udev system for the first time">
588 (EE) xf86OpenSerial: Cannot open device /dev/mouse
589 No such file or directory.
590 (EE) Mouse0: cannot open input device
591 (EE) PreInit failed for input device "Mouse0"
592 No core pointer
593 </pre>
594
595 <p>
596 To correct this, open your X11 config in a text editor, and update the mouse
597 <e>InputDevice</e> section to use the <path>/dev/input/mice</path> device. An
598 example is shown below:
599 </p>
600
601 <pre caption="Opening your X11 config file">
602 # <i>nano -w /etc/X11/xorg.conf</i>
603 </pre>
604
605 <note>
606 If you are still using XFree86, your config file will be
607 <path>/etc/X11/XF86Config</path>
608 </note>
609
610 <pre caption="Sample mouse InputDevice section">
611 Section "InputDevice"
612 Identifier "Mouse0"
613 Driver "mouse"
614 Option "Protocol" "auto"
615 Option "Device" "/dev/input/mice"
616 EndSection
617 </pre>
618
619 <note>
620 If you are using a serial mouse, the new device path will be
621 <path>/dev/tts/0</path> instead of <path>/dev/ttyS0</path>.
622 </note>
623
624 </body>
625 </section>
626 <section>
627 <title>New Serial-ATA (SATA) drivers name the devices differently</title>
628 <body>
629
630 <p>
631 If you used the original Serial ATA drivers under Linux 2.4, you probably
632 observed your SATA devices having names such as <path>/dev/hde</path>.
633 </p>
634
635 <p>
636 Linux 2.6 introduces some new SATA drivers (libata) which are based on the SCSI
637 subsystem. As these drivers are based on SCSI, your SATA disks will now show up
638 as SCSI devices. Your first SATA disk will be named <path>/dev/sda</path>. You will
639 need to update your <path>/etc/fstab</path> file to reflect this, and you will need
640 to bear this in mind when choosing the root/real_root kernel boot parameter
641 later on.
642 </p>
643
644 <note>
645 libata has been backported into recent versions of Linux 2.4, so you may
646 already be familiar with the new device naming.
647 </note>
648
649 </body>
650 </section>
651 <section>
652 <title>bootsplash no longer maintained</title>
653 <body>
654
655 <p>
656 If you used the <c>gentoo-sources-2.4</c> kernel, you may have used the
657 <e>bootsplash</e> functionality in order to provide yourself with a colourful
658 framebuffer console.
659 </p>
660
661 <p>
662 The developer of bootsplash appears to have lost interest in his project, given
663 some design problems. However, Gentoo developer <e>Michał Januszewski</e> is
664 developing a successor, <c>gensplash</c>, which in included in the
665 gentoo-sources-2.6 kernel. You can follow Michał's <uri
666 link="http://dev.gentoo.org/~spock/projects/gensplash/archive/gensplash-in-5-easy-steps.txt">
667 Gensplash in 5 easy steps</uri> document in order to familiarize yourself with
668 how gensplash is operated.
669 </p>
670
671 </body>
672 </section>
673 <section>
674 <title>I2C drivers now included in the kernel</title>
675 <body>
676
677 <p>
678 If you use <c>lm-sensors</c> to monitor system temperatures and power levels,
679 you previously needed to install the <c>i2c</c> package in order to provide
680 hardware support.
681 </p>
682
683 <p>
684 The I2C hardware drivers are now included in the Linux 2.6 kernel, no external
685 i2c package is required. Remember to compile support for your specific I2C
686 devices into the kernel configuration. You will then be able to use
687 <c>lm-sensors</c> as usual.
688 </p>
689
690 </body>
691 </section>
692
693
694 </chapter>
695
696 <chapter id="conf">
697 <title>Configuring, building, and installing the kernel</title>
698 <section>
699 <body>
700
701 <p>
702 As with Linux 2.4, you have two options for managing your new kernel build.
703 </p>
704
705 <ol>
706 <li>
707 The default method is to configure your kernel manually. This may seem
708 daunting but is the preferred way as long as you know your system. If you
709 wish to configure your new kernel manually, please continue on to the <uri
710 link="#manual">next chapter</uri>.
711 </li>
712 <li>
713 The alternative option is to use our <c>genkernel</c> utility to
714 automatically configure, compile, and install a kernel for you. If you wish
715 to use <c>genkernel</c> then skip over the next chapter and proceed with
716 <uri link="#genkernel">using genkernel</uri>.
717 </li>
718 </ol>
719
720 </body>
721 </section>
722 </chapter>
723
724 <chapter id="manual">
725 <title>Default: Manual configuration</title>
726 <section>
727 <title>Configuring the kernel</title>
728 <body>
729
730 <p>
731 We'll now get on with configuring the kernel. Open menuconfig in the usual way:
732 </p>
733
734 <pre caption="Invoking menuconfig">
735 # <i>cd /usr/src/linux</i>
736 # <i>make menuconfig</i>
737 </pre>
738
739 <p>
740 You will probably be familiar with using menuconfig from configuring 2.4
741 kernels. Fortunately, the front end has barely changed at all, but you will
742 observe much better organisation of kernel options, plus <e>many</e> new
743 options that weren't present in 2.4.
744 </p>
745
746 <p>
747 Be sure to enable the following important kernel options:
748 </p>
749
750 <pre caption="Required kernel options">
751 File systems ---&gt;
752 Pseudo Filesystems ---&gt;
753 [*] /proc file system support
754 [*] Virtual memory file system support (former shm fs)
755
756 <comment>(the following are required for udev):</comment>
757 General setup ---&gt;
758 [*] Support for hot-pluggable devices
759
760 <comment>(the following are required for ALSA):</comment>
761 Device Drivers ---&gt;
762 Sound ---&gt;
763 &lt;*&gt; Sound card support
764 Advanced Linux Sound Architecture ---&gt;
765 &lt;M&gt; Advanced Linux Sound Architecture
766 &lt;M&gt; Sequencer support
767 &lt;M&gt; OSS Mixer API
768 [*] OSS Sequencer API
769 <comment> (and do not forget to select your soundcard from the submenus!)</comment>
770
771 <comment>(the following are required if you use LVM for disk management):</comment>
772 Device Drivers ---&gt;
773 Multi-device support (RAID and LVM) ---&gt;
774 [*] Multiple devices driver support (RAID and LVM)
775 &lt;*&gt; Device mapper support
776 </pre>
777
778 <warn>
779 Previously you may have included support for the <path>/dev</path> file system
780 (now marked OBSOLETE). Do not enable devfs support. We have installed udev,
781 which we will be using instead of devfs from now on.
782 </warn>
783
784 <p>
785 Also, remember to enable support for the filesystems that you use, and the
786 hardware present in your system. Be sure to enable support for the IDE
787 controller on your motherboard if you wish to benefit from fast DMA disk
788 access. Refer to the <uri
789 link="/doc/en/handbook/handbook-x86.xml?part=1&amp;chap=7">Configuring the
790 Kernel</uri> section of the <uri link="/doc/en/handbook/index.xml">Gentoo
791 Handbook</uri> for additional guidance here.
792 </p>
793
794 </body>
795 </section>
796 <section>
797 <title>Building the kernel</title>
798 <body>
799
800 <p>
801 Now that we have configured the kernel, we can start the compilation process:
802 </p>
803
804 <pre caption="Compiling the kernel source">
805 # <i>make &amp;&amp; make modules_install</i>
806 </pre>
807
808 <note>
809 You may recall having to run <c>make dep</c> with Linux 2.4 sources. This is no
810 longer required.
811 </note>
812
813 <p>
814 Wait for the kernel compilation to complete (and observe the much more readable
815 compilation output).
816 </p>
817
818 </body>
819 </section>
820 <section>
821 <title>Installing the kernel</title>
822 <body>
823
824 <p>
825 The next step is mounting your <path>/boot</path> partition and copying the
826 kernel image over. You must then update your bootloader config manually.
827 </p>
828
829 <pre caption="Installing the kernel">
830 # <i>mount /boot</i>
831 # <i>cp arch/i386/boot/bzImage /boot/bzImage-2.6.10-gentoo-r4</i>
832 </pre>
833
834 <p>
835 Note that the above instructions are examples only, you should follow your
836 usual procedure of updating kernels by following the instructions in the <uri
837 link="/doc/en/handbook/index.xml">Gentoo Handbook</uri> (see the <uri
838 link="/doc/en/handbook/handbook-x86.xml?part=1&amp;chap=7">Configuring the
839 Kernel</uri> chapter).
840 </p>
841
842 <p>
843 When updating your bootloader config, do not remove the old entry pointing at
844 your 2.4 kernel. This way, you will easily be able to switch between the two if
845 something is not working.
846 </p>
847
848 <p>
849 Now continue onto the <uri link="#modules">Module Configuration</uri> section.
850 </p>
851
852 </body>
853 </section>
854 </chapter>
855
856 <chapter id="genkernel">
857 <title>Alternative: Using genkernel</title>
858 <section>
859 <body>
860
861 <p>
862 If you prefer to use genkernel instead of manually configuring your kernel, you
863 will be happy to hear that using genkernel to produce 2.6 kernels is very
864 similar to the process you performed when producing your previous 2.4 kernel.
865 </p>
866
867 <p>
868 You should invoke genkernel as shown below:
869 </p>
870
871 <pre caption="Invoking genkernel with some common arguments">
872 # <i>genkernel --udev --menuconfig --bootloader=grub all</i>
873 </pre>
874
875 <p>
876 In the above example, we also take advantage of genkernel features to open
877 menuconfig to allow you to customise the kernel configuration (if you wish),
878 and to update the grub bootloader configuration after compilation.
879 </p>
880
881 <p>
882 You should choose genkernel arguments that suit you, but do not forget to
883 include the <c>--udev</c> argument! Refer to the <uri
884 link="/doc/en/genkernel.xml">Gentoo Linux Genkernel Guide</uri> and the <uri
885 link="/doc/en/handbook/handbook-x86.xml?part=1&amp;chap=7">Configuring the
886 Kernel</uri> chapter of the <uri link="/doc/en/handbook/index.xml">Gentoo
887 Handbook</uri> for additional information.
888 </p>
889
890 <p>
891 If you choose to update your bootloader config yourself, then you must remember
892 to include the <c>udev</c> kernel parameter. A sample <e>grub</e> config
893 section is shown below, but remember to adjust the <e>real_root</e> parameter
894 for your system.
895 </p>
896
897 <pre caption="Sample GRUB config for genkernel + udev">
898 title Gentoo Linux (2.6 kernel)
899 root (hd0,0)
900 kernel /kernel-2.6.10-gentoo-r4 <i>udev</i> root=/dev/ram0 init=/linuxrc ramdisk=8192 real_root=/dev/hda3
901 initrd /initrd-2.6.10-gentoo-r4
902 </pre>
903
904 </body>
905 </section>
906 </chapter>
907
908 <chapter id="modules">
909 <title>Module Configuration</title>
910
911 <section>
912 <title>Installing external modules</title>
913 <body>
914
915 <p>
916 Many users will additionally rely on kernel modules that are built outside of
917 the kernel tree. Common examples are the binary ATI and Nvidia graphics
918 drivers. You now need to install those modules, which will compile against the
919 2.6 sources found at <path>/usr/src/linux</path>. This is the usual case of
920 <c>emerge packagename</c> for all the external modules you are used to using
921 with 2.4.
922 </p>
923
924 <p>
925 Refer again to the <uri
926 link="/doc/en/handbook/handbook-x86.xml?part=1&amp;chap=7">Configuring the
927 Kernel</uri> chapter of the <uri link="/doc/en/handbook/index.xml">Gentoo
928 Handbook</uri> for more info.
929 </p>
930
931 </body>
932 </section>
933 <section>
934 <title>Autoloading modules</title>
935 <body>
936
937 <p>
938 You may have decided to compile some kernel components as modules (as opposed
939 to compiled directly into the kernel) and would like to have them autoloaded on
940 bootup like you did with 2.4. Also, if you installed any external modules from
941 the portage tree (as described above) you will probably want to autoload them
942 too.
943 </p>
944
945 <p>
946 You can achieve this similarly as to how you did with 2.4. Simply open up the
947 file <path>/etc/modules.autoload.d/kernel-2.6</path> in a text editor and list
948 the names of the modules you would like autoloaded.
949 </p>
950
951 <pre caption="Opening the module autoload list in nano">
952 # <i>nano -w /etc/modules.autoload.d/kernel-2.6</i>
953 </pre>
954
955 <pre caption="Sample autoload list to load the 3c59x and nvidia modules">
956 # /etc/modules.autoload.d/kernel-2.6: kernel modules to load when system boots.
957 #
958 # Note that this file is for 2.6 kernels.
959 #
960 # Add the names of modules that you'd like to load when the system
961 # starts into this file, one per line. Comments begin with # and
962 # are ignored. Read man modules.autoload for additional details.
963
964 3c59x
965 nvidia
966 </pre>
967
968 </body>
969 </section>
970 </chapter>
971
972 <chapter>
973 <title>LVM to LVM2 migration</title>
974 <section>
975 <title>Upgrading to LVM2 tools</title>
976 <body>
977
978 <note>
979 If you do not use LVM to manage your disk storage, you can safely skip this
980 chapter and skip onto the next.
981 </note>
982
983 <p>
984 Fortunately, upgrading from the LVM1 user tools to the LVM2 versions is very
985 simple:
986 </p>
987
988 <pre caption="Upgrading user-tools from LVM1 to LVM2">
989 # <i>emerge --unmerge lvm-user</i>
990 # <i>emerge lvm2</i>
991 </pre>
992
993 <note>
994 You will need to re-emerge <c>lvm-user</c> if you plan to go back to booting a
995 2.4 kernel, as <c>lvm2</c> by itself isn't enough for 2.4 kernels.
996 </note>
997
998 </body>
999 </section>
1000 </chapter>
1001
1002 <chapter>
1003 <title>Booting into Linux 2.6</title>
1004 <section>
1005 <body>
1006
1007 <p>
1008 It's now time to boot into Linux 2.6. Close all applications and reboot:
1009 </p>
1010
1011 <pre caption="Rebooting">
1012 # <i>umount /boot</i>
1013 # <i>reboot</i>
1014 </pre>
1015
1016 <p>
1017 When you reboot, if you followed this document correctly so far, you will have
1018 the option of either loading Linux 2.4 or Linux 2.6 from your bootloader.
1019 Choose Linux 2.6.
1020 </p>
1021
1022 <p>
1023 Once the system has booted, check that things are working. If you made a
1024 mistake in the kernel configuration, don't worry, you can skip back to the <uri
1025 link="#conf">Configuring, building, and installing the kernel</uri> section,
1026 make your change, recompile and install new kernel image, reboot, and try
1027 again!
1028 </p>
1029
1030 </body>
1031 </section>
1032 <section>
1033 <title>Configuring and unmuting ALSA</title>
1034 <body>
1035
1036 <p>
1037 We will now complete the ALSA configuration and unmute the audio channels. The
1038 ALSA packages provide a useful utility to make this process relatively simple:
1039 </p>
1040
1041 <pre caption="Invoking the automatic ALSA configuration utility">
1042 # <i>alsaconf</i>
1043 </pre>
1044
1045 <p>
1046 The process is straightforward: allow the <e>/etc/modules.d/alsa</e> file to be
1047 automatically updated, and then allow ALSA to be reloaded. alsaconf will then
1048 terminate, however you will need to run it multiple times if you have multiple
1049 sound devices installed in your system.
1050 </p>
1051
1052 <p>
1053 You should now add <c>alsasound</c> to your boot runlevel, so that volumes will
1054 be saved on shutdown and restored on bootup:
1055 </p>
1056
1057 <pre caption="Adding alsasound to the boot runlevel">
1058 # <i>rc-update add alsasound boot</i>
1059 </pre>
1060
1061 <note>
1062 The <c>alsaconf</c> utility chooses initial volume levels for your sound
1063 devices. If these are inappropriate, you can modify them at any time with the
1064 <c>alsamixer</c> utility.
1065 </note>
1066
1067 </body>
1068 </section>
1069 <section>
1070 <title>Any immediate problems?</title>
1071 <body>
1072
1073 <p>
1074 At this stage you should refer back to the <uri link="#pitfalls">Known pitfalls
1075 with Linux 2.6 migration</uri> section which may be helpful with any issues you
1076 encounter immediately.
1077 </p>
1078
1079 </body>
1080 </section>
1081 </chapter>
1082
1083 <chapter>
1084 <title>Header files and NPTL</title>
1085 <section>
1086 <body>
1087
1088 <p>
1089 By now you are running Linux 2.6 and hopefully have all issues ironed out. You
1090 should now update your Linux kernel header files and re-merge glibc so that
1091 userspace applications can take advantage of new Linux 2.6 features.
1092 </p>
1093
1094 <pre caption="Updating to linux-headers">
1095 # <i>emerge -u linux-headers</i>
1096 </pre>
1097
1098 <p>
1099 After updating your headers package, you should generally re-merge glibc.
1100 There is a new feature here that you may be interested in - NPTL. NPTL is a new
1101 threading model present in Linux 2.6, which features much quicker thread create
1102 and destroy times. This won't make much of a difference to most systems, but
1103 you may wish to enable it during this migration process! To enable NPTL, edit
1104 <path>/etc/make.conf</path>, adding <e>nptl</e> to your USE variable.
1105 </p>
1106
1107 <warn>
1108 If you choose to also enable the "nptlonly" flag, be aware that you will no
1109 longer be able to boot a 2.4 kernel.
1110 </warn>
1111
1112 <p>
1113 Now re-merge glibc (you should do this even if you did not choose to enable
1114 NPTL).
1115 </p>
1116
1117 <pre caption="Reinstalling glibc against the new kernel headers">
1118 # <i>emerge -a glibc</i>
1119 </pre>
1120
1121 <p>
1122 If you enabled NPTL, existing binaries will not use it until they are
1123 recompiled. However, any binaries compiled from this point onwards <e>will</e>
1124 use NPTL. You may wish to recompile all binaries now, e.g.:
1125 </p>
1126
1127 <pre caption="Recompiling all packages on the system">
1128 # <i>emerge -e world</i>
1129 </pre>
1130
1131 <p>
1132 Alternatively, you can just let your system "naturally" convert itself to NPTL
1133 as you update to newer versions of packages when they are released.
1134 </p>
1135
1136 </body>
1137 </section>
1138 </chapter>
1139
1140 <chapter>
1141 <title>Closing remarks</title>
1142 <section>
1143 <title>Problems?</title>
1144 <body>
1145
1146 <p>
1147 With the incredible amount of work that went into Linux 2.6, it is sometimes
1148 inevitable that things which used to work fine, no longer function as expected.
1149 </p>
1150
1151 <p>
1152 If you have any problems with your 2.6 kernel, and you can confirm that this
1153 problem does not exist with Linux 2.4, then please open a bug with us on our
1154 <uri link="http://bugs.gentoo.org">Bugzilla</uri>. We will investigate the
1155 issue, and if we find that it is a problem in the mainline kernel, we may then
1156 ask you to file a report at the central kernel bugzilla.
1157 </p>
1158
1159 </body>
1160 </section>
1161 <section>
1162 <title>Conclusion</title>
1163 <body>
1164
1165 <p>
1166 Hopefully you have just completed a smooth migration and you are enjoying the
1167 benefits which Linux 2.6 brings over 2.4.
1168 </p>
1169
1170 <p>
1171 I would like to say a word of thanks to the many users who effectively 'tested'
1172 this document while it was in its early stages, and provided feedback about how
1173 the migration process went. Sorry that I did not reply to all the emails (there
1174 were a lot!), but I did read every one, and refined this document where
1175 appropriate. Enjoy your 2.6-enhanced systems :)
1176 </p>
1177
1178 </body>
1179 </section>
1180 <section>
1181 <title>Removing Linux 2.4 from your system</title>
1182 <body>
1183
1184 <p>
1185 After you have been running 2.6 for a while, you may decide that you no longer
1186 have any requirement to be able to use Linux 2.4. The steps you can take to
1187 clean up your system are detailed below. <e>Only follow the procedure in this
1188 section if you are sure that you don't want/need to use 2.4 again!</e>
1189 </p>
1190
1191 <p>
1192 The 2.4 kernel source code can be removed, using the emerge utility as usual.
1193 For example, assuming you have 2.4 versions of vanilla-sources and
1194 gentoo-sources installed, you could use the following command to remove them
1195 while keeping the 2.6 versions intact:
1196 </p>
1197
1198 <pre caption="Example: Removing Linux 2.4 sources">
1199 # <i>emerge --unmerge =vanilla-sources-2.4.* =gentoo-sources-2.4.*</i>
1200 </pre>
1201
1202 <p>
1203 Portage will not completely clean out your 2.4 kernel source installations,
1204 because some temporary files are created during compilation. It is safe to
1205 remove these remnants with the following command:
1206 </p>
1207
1208 <pre caption="Removing remaining temporary files">
1209 # <i>rm -rf /usr/src/linux-2.4.*</i>
1210 </pre>
1211
1212 <p>
1213 You can additionally remove modules and information files relating to your old
1214 2.4 kernel installations, as these are no longer needed.
1215 </p>
1216
1217 <pre caption="Removing previously-installed 2.4 modules">
1218 # <i>rm -rf /lib/modules/2.4.*</i>
1219 </pre>
1220
1221 <p>
1222 The 2.4 kernel binaries you used to boot from can also be safely removed. You
1223 should mount your <c>/boot</c> partition, and remove those images. You should
1224 also update your bootloader configuration so that it no longer references these
1225 deleted kernel images.
1226 </p>
1227
1228 <p>
1229 Some Linux 2.4 users will have previously installed the <c>alsa-driver</c>
1230 package to benefit from the new audio capabilities included in Linux 2.6. If
1231 you were one of these users, and you followed the advice given earlier in this
1232 document about building ALSA with the 2.6 kernel sources (as opposed to using
1233 the <c>alsa-driver</c> package), then you can safely remove this to prevent
1234 future conflicts.
1235 </p>
1236
1237 <p>
1238 Additionally, <c>lm-sensors</c> users will have previously used the <c>i2c</c>
1239 package to provide the hardware drivers. As already mentioned, I2C drivers are
1240 now included in the kernel, so this package can also be removed in order to
1241 prevent future conflicts.
1242 </p>
1243
1244 <p>
1245 The devfs management daemon, <c>devfsd</c>, can also safely be removed, now
1246 that we are using <c>udev</c> for device management.
1247 </p>
1248
1249 <pre caption="Removing alsa-driver, i2c, and devfsd">
1250 # <i>emerge --unmerge alsa-driver i2c devfsd</i>
1251 </pre>
1252
1253 <p>
1254 If you are LVM2 user, you may wish to convert your data into the LVM2 data
1255 format in order to benefit from the advantages which LVM2 provides. However,
1256 this operation will prevent you from ever accessing your LVM data from a 2.4
1257 kernel. If you want to continue with the conversion (this is totally
1258 optional!), then you should examine the <c>vgconvert</c> man page for
1259 instructions on how to carry this out. An example is shown below, where
1260 <c>main</c> is the volume group name.
1261 </p>
1262
1263 <pre caption="Converting a LVM1 volume to LVM2 format">
1264 # <i>vgconvert -M2 main</i>
1265 </pre>
1266
1267 </body>
1268 </section>
1269 </chapter>
1270 </guide>

  ViewVC Help
Powered by ViewVC 1.1.20