/[gentoo]/xml/htdocs/doc/en/genkernel.xml
Gentoo

Contents of /xml/htdocs/doc/en/genkernel.xml

Parent Directory Parent Directory | Revision Log Revision Log


Revision 1.30 - (hide annotations) (download) (as text)
Fri Sep 21 23:01:43 2007 UTC (6 years, 7 months ago) by nightmorph
Branch: MAIN
Changes since 1.29: +2 -2 lines
File MIME type: application/xml
marking the genkernel guide obsolete for the time being, it needs a complete rewrite. too bad for such an imporant(?) widely used tool, but i asked wolf31o2 for updates in bug 173766. nothing for the last 3 months.

1 cam 1.24 <?xml version="1.0" encoding="UTF-8"?>
2 nightmorph 1.30 <!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/genkernel.xml,v 1.29 2007/06/21 01:38:07 nightmorph Exp $ -->
3 swift 1.1 <!DOCTYPE guide SYSTEM "/dtd/guide.dtd">
4    
5 nightmorph 1.30 <guide link="/doc/en/genkernel.xml" disclaimer="obsolete">
6 swift 1.1 <title>Gentoo Linux Genkernel Guide</title>
7    
8     <author title="Author">
9     <mail link="plasmaroo@gentoo.org">Tim Yamin</mail>
10     </author>
11    
12 plasmaroo 1.17 <!-- folajimi@speakeasy.net -->
13     <author title="Contributor">
14     Jimi Ayodele
15     </author>
16    
17     <!-- thseiler@gmail.com -->
18     <author title="NFS Support">
19     Thomas Seiler
20     </author>
21    
22 swift 1.1 <abstract>
23 plasmaroo 1.17 This guide intends to provide a reference of all the functions provided by
24 cam 1.24 genkernel.
25 swift 1.1 </abstract>
26    
27 plasmaroo 1.4 <license/>
28    
29 nightmorph 1.29 <version>1.5</version>
30     <date>2007-06-20</date>
31 swift 1.1
32     <chapter>
33     <title>Introduction</title>
34     <section>
35 plasmaroo 1.17 <title>Rationale</title>
36 swift 1.1 <body>
37    
38     <p>
39 plasmaroo 1.17 For users who are not privy to kernel compilation, genkernel is a tool to
40     automate this process. It can help you create a kernel image akin to those
41     available on Gentoo Installation CDs, which are designed to auto-detect the
42     hardware configuration of your system. Some users may also be interested in
43     using genkernel for hardware requiring initialization and a working kernel
44     before the system starts up. Since genkernel automatically compiles your kernel
45     modules, you can use hardware that may require certain module parameters to be
46     loaded for proper operation.
47 swift 1.1 </p>
48    
49     </body>
50     </section>
51     <section>
52 plasmaroo 1.17 <title>Target Audience</title>
53 swift 1.1 <body>
54    
55     <p>
56 plasmaroo 1.17 If you are either uncertain about how to compile a kernel, or are just
57     unfamiliar with your hardware configuration, genkernel is a very handy tool.
58     It is designed to take the pain out of the kernel compiling process, and
59     supports most hardware by default.
60 swift 1.1 </p>
61    
62     <p>
63 plasmaroo 1.17 However, if you know what drivers are required by your system, you may be able
64     to further reduce the time taken to compile the kernel. This is possible since
65     you can direct genkernel to only build drivers relevant to your hardware.
66     Oftentimes, the number of drivers required by your system will be fewer
67     (implying a shorter kernel compilation time) than the default configuration
68     provides.
69 swift 1.1 </p>
70    
71     </body>
72     </section>
73     <section>
74 plasmaroo 1.17 <title>Installing genkernel</title>
75 swift 1.1 <body>
76    
77     <p>
78 plasmaroo 1.17 To obtain genkernel, run <c>emerge genkernel</c> from the command line. If you
79 neysx 1.23 are using the <uri
80 vanquirius 1.26 link="/doc/en/handbook/2005.1/hb-install-about.xml#doc_chap2_sect1">Gentoo
81 neysx 1.23 Reference Platform</uri> (GRP), remember to install binary packages by passing
82     the <c>-k</c> flag to emerge. Since the GRP is bundled with an older version of
83     genkernel, the flags may be different. In any case, consult <c>genkernel
84     --help</c> for help on how to use the version of genkernel installed on your
85     system.
86 swift 1.1 </p>
87 cam 1.24
88 swift 1.1 </body>
89     </section>
90 plasmaroo 1.17 </chapter>
91    
92     <chapter>
93     <title>Working with genkernel</title>
94 swift 1.1 <section>
95 plasmaroo 1.17 <title>How to use genkernel</title>
96 swift 1.1 <body>
97    
98     <p>
99 plasmaroo 1.17 Although there are several ways to run genkernel, the least-intrusive approach
100     is provided by <c>genkernel all</c>. Here, a generic configuration which works
101     well for most systems is used. As was mentioned earlier, this approach is not
102     without drawbacks; most of the modules created are useless to the average user
103     and may increase compile time. Below is an illustration of a more efficient
104     approach, achieved by passing certain flags to genkernel as root:
105     </p>
106    
107     <pre caption="Running genkernel (with flags)">
108 neysx 1.23 # <i>genkernel --bootsplash --no-install --no-clean --menuconfig all</i>
109 plasmaroo 1.17 </pre>
110    
111     <p>
112     The above operation causes genkernel to create a bootsplash-enabled kernel
113     (<c>--bootsplash</c>) that will have to be manually installed
114     (<c>--no-install</c>). While preparing the kernel source tree, genkernel will
115     refrain from cleaning out any preexisting object files present in the source
116     tree (<c>--no-clean</c>). A menu-driven kernel configuration utility will be
117     displayed that allows the user to select which modules will be built for the
118     system (<c>--menuconfig</c>).
119     </p>
120    
121     <p>
122     There are other flags which alter the result provided by genkernel. For
123     instance, replacing <c>--no install</c> with the <c>--install</c> flag allows
124     genkernel to automatically install the new kernel in the <path>/boot</path>
125     directory. Using the <c>--mountboot</c> flag allows genkernel to mount your
126     <path>/boot</path> partition automatically, if necessary.
127     </p>
128    
129     <p>
130     Remember, genkernel is designed to make kernel compilation easy and
131     stress-free. For this reason, genkernel features several flags to ease the
132     kernel compilation effort. For example, there are flags to help with kernel
133     configuration, while others affect the actual compilation. Some flags even help
134     debug the compilation process. For those interested in further optimization,
135     there are flags that affect kernel assembling, packaging and even kernel
136     initialization.
137     </p>
138    
139     <p>
140     The rest of this chapter examines the functionality of various flags and
141     actions available for genkernel. Some of the flags have variants which perform
142     a converse operation. The converse variants carry the <b><c>no-</c></b> prefix,
143     and their effects are enclosed within the square brackets, [].
144 swift 1.1 </p>
145    
146     </body>
147     </section>
148     <section>
149 plasmaroo 1.17 <title>Configuration Flags</title>
150 swift 1.1 <body>
151    
152     <p>
153 plasmaroo 1.17 The configuration flags listed below exist to help you decide what features
154     should be enabled or disabled in the kernel prior to compilation. You can even
155     choose whether or not the configuration file created in the process should be
156     saved. The following are the primary configuration flags:
157 swift 1.1 </p>
158    
159     <ul>
160 neysx 1.23 <li>
161     <b>--<c>no-</c>menuconfig</b>: Activates <e>[or deactivates]</e> the
162     <c>make menuconfig</c> command (which invokes an interactive, menu-based
163     kernel configuration utility), before building the kernel.
164     </li>
165     <li>
166     <b>--gconfig</b>: Provides a kernel configuration utility which depends on
167     the GTK+ libraries. The advantage of this option is that most users find it
168     easier and clearer to configure the kernel using this tool, since it relies
169     on the X-windowing system. The disadvantage of this option is that you
170     <b>need</b> the X-windowing system to use it, so it will not work on the
171     command line.
172     </li>
173     <li>
174     <b>--xconfig</b>: Provides a kernel configuration utility which depends on
175     the QT libraries. The advantage of this option is that most users find it
176     easier and clearer to configure the kernel using this tool, since it relies
177     on the X-windowing system. The disadvantage of this option is that you
178     <b>need</b> the X-windowing system to use it, so it will not work on the
179     command line.
180     </li>
181     <li>
182 cam 1.25 <b>--<c>no-</c>save-config</b>: Saves <e>[or does not save]</e> the kernel
183 neysx 1.23 configuration to a file in the <path>/etc/kernels/</path> directory for
184     later use.
185     </li>
186 swift 1.1 </ul>
187    
188     </body>
189     </section>
190     <section>
191 plasmaroo 1.17 <title>Compilation Flags</title>
192 swift 1.1 <body>
193    
194     <p>
195 plasmaroo 1.17 The following flags usually take effect during the actual compilation:
196 swift 1.1 </p>
197    
198     <ul>
199     <li>
200 neysx 1.23 <b>--kerneldir=<path>/path/to/sources/</path></b>: Specifies an alternative
201     kernel source location, rather than the default
202 plasmaroo 1.17 <path>/usr/src/linux/</path> location.
203 swift 1.1 </li>
204     <li>
205 plasmaroo 1.17 <b>--kernel-config=<path>/path/to/config-file</path></b>: Specifies what
206     alternative kernel configuration will be used, rather than the default
207     <path>/path/to/sources/.config</path> file.
208 swift 1.1 </li>
209     <li>
210 neysx 1.23 <b>--module-prefix=<path>/path/to/prefix-directory/</path></b>: Specifies a
211     prefix to the directory where kernel modules will be installed (default
212 plasmaroo 1.17 path is the <path>/lib/modules/</path> directory.)
213 swift 1.1 </li>
214     </ul>
215    
216     <ul>
217     <li>
218 neysx 1.23 <b>--<c>no-</c>clean</b>: Activates <e>[or deactivates]</e> the <c>make
219     clean</c> command before compiling your kernel. The <c>make clean</c>
220     command removes all object files and dependencies from the kernel's source
221     tree.
222 swift 1.1 </li>
223     <li>
224 neysx 1.23 <b>--<c>no-</c>mrproper</b>: Activates <e>[or deactivates]</e> the <c>make
225     mrproper</c> command before kernel compilation. Like the <c>make clean</c>
226     command, <c>make mrproper</c> removes all object files and dependencies
227     from the kernel's source tree. However, any previous configuration files
228     (in <path>/path/to/sources/.config</path> or
229     <path>/path/to/sources/.config.old</path>) will <b>also</b> be purged from
230     the kernel's source tree.
231 swift 1.1 </li>
232     <li>
233 plasmaroo 1.17 <b>--oldconfig</b>: Issues the <c>make oldconfig</c> command, which
234 neysx 1.23 attempts to collect configuration information for the system's architecture
235     from a generic script in <path>/usr/share/genkernel/</path>. This is a
236     non-interactive process; no user input is entertained. Also, if
237 plasmaroo 1.17 <c>--oldconfig</c> is used in conjunction with <c>--clean</c>, the latter
238 neysx 1.23 flag is negated, resulting in the activation of the <c>--no-clean</c> flag.
239 swift 1.1 </li>
240 plasmaroo 1.17 </ul>
241    
242     <ul>
243 neysx 1.23 <li>
244     <b>--callback="<c>echo hello</c>"</b>: Calls the specified arguments
245     (<c>echo hello</c>, in this case) after the kernel and the relevant modules
246     have been built, but before building the initrd image. This may be useful
247     if you want to install external modules in the initrd image by emerging the
248     relevant item(s) with the callback feature, and then redefining a genkernel
249     module group.
250     </li>
251 swift 1.1 </ul>
252    
253     <ul>
254 neysx 1.23 <li>
255     <b>--<c>no-</c>install</b>: Activates <e>[or deactivates]</e> the <c>make
256     install</c> command, which installs your new kernel image, configuration
257     file, initrd image and system map onto your mounted boot partition. Any
258     compiled modules will be installed as well.
259     </li>
260     <li>
261     <b>--<c>no-</c>initrdmodules</b>: Refrains from copying any modules to the
262     genkernel-created initrd image. This flag is an exception to the rule about
263     the <c>no-</c> prefix; omission of this prefix creates an invalid genkernel
264     flag.
265     </li>
266     <li>
267     <b>--genzimage</b>: Creates the initrd image, prior to the kernel image.
268     (This hack currently applies only to PPC Pegasos systems.)
269     </li>
270 swift 1.1 </ul>
271    
272     </body>
273     </section>
274     <section>
275 plasmaroo 1.17 <title>Compiler Flags</title>
276 swift 1.1 <body>
277    
278     <p>
279 plasmaroo 1.17 The following flags are supported by genkernel, and are passed to the relevant
280     applications while the kernel is being assembled. These flags affect the
281     <e>compiler</e> used for the kernel compilation process, albeit at a much lower
282     level.
283 swift 1.1 </p>
284    
285     <ul>
286 neysx 1.23 <li>
287     <b>--kernel-cc=<c>someCompiler</c></b>: Specifies the compiler employed
288     during the kernel compilation process.
289     </li>
290     <li>
291     <b>--kernel-ld=<c>someLinker</c></b>: Specifies the linker employed during
292     the kernel compilation process.
293     </li>
294     <li>
295     <b>--kernel-as=<c>someAssembler</c></b>: Specifies the assembler employed
296     during the kernel compilation process.
297     </li>
298     <li>
299     <b>--kernel-make=<c>someMake</c></b>: Specifies an alternative to the
300     <e>GNU make</e> utility employed during the kernel compilation process.
301     </li>
302 plasmaroo 1.17 </ul>
303    
304     <ul>
305 neysx 1.23 <li>
306     <b>--utils-cc=<c>someCompiler</c></b>: Specifies the compiler employed
307     during the compilation of support utilities.
308     </li>
309     <li>
310     <b>--utils-ld=<c>someLinker</c></b>: Specifies the linker employed during
311     the compilation of support utilities.
312     </li>
313     <li>
314     <b>--utils-as=<c>someAssembler</c></b>: Specifies the assembler employed
315     during the compilation of support utilities.
316     </li>
317     <li>
318     <b>--utils-make=<c>someMake</c></b>: Specifies an alternative to the <e>GNU
319     make</e> utility employed during the compilation of support utilities.
320     </li>
321 plasmaroo 1.17 </ul>
322    
323     <ul>
324 neysx 1.23 <li>
325     <b>--makeopts=<c>-jX</c></b>: Specifies the number of concurrent threads
326     that the make utility can implement while the kernel (and utilities) are
327     being compiled. The variable <b>'X'</b> is a number obtained by adding one
328     (1) to the number of CPUs used by the system. So, for a system with one
329     CPU, the appropriate flag is <c>-j2</c>; a system with two CPUs will use
330     the <c>-j3</c> flag, and so on. <e>(A system with one processor that
331 cam 1.25 supports Hyper-Threading&trade; (HT) Technology can use the
332     </e><c>-j3</c><e> flag, provided Symmetric Multi-Processing (SMP) support is
333     enabled in the kernel.)</e>
334 neysx 1.23 </li>
335 swift 1.1 </ul>
336    
337 plasmaroo 1.17 </body>
338     </section>
339     <section>
340     <title>Debugging Flags</title>
341     <body>
342    
343     <p>
344 rane 1.27 The use of debugging flags during the kernel compilation process controls the
345 plasmaroo 1.17 amount of information reported, as well as the presentation of said data.
346     </p>
347    
348 swift 1.1 <ul>
349 neysx 1.23 <li>
350     <b>--debuglevel=<c>verblevel</c></b>: Controls the level of verbosity for
351     information provided by genkernel. The variable <c>verblevel</c> is an
352     integer between 0 and 5. The level '0' represents minimal output, while '5'
353     provides as much information as possible about genkernel's activities
354     during the kernel compilation process.
355     </li>
356     <li>
357     <b>--debugfile=<path>/path/to/outputfile</path></b>: Ignores the value set
358     by the <c>--debuglevel</c> argument, and sends <b>all</b> debugging data
359     produced by genkernel to the specified output file, which is located at
360     <path>/var/log/genkernel.log</path> by default.
361     </li>
362     <li>
363 cam 1.25 <b>--no-color</b>: Activates <e>[or deactivates]</e> colored output of
364     debugging information (reported by genkernel) using escape sequences.
365 neysx 1.23 </li>
366 swift 1.1 </ul>
367    
368 plasmaroo 1.17 </body>
369     </section>
370    
371     <section>
372     <title>Initialization Flags</title>
373     <body>
374    
375     <p>
376     The flags here are used to create certain effects during system startup. Some
377     of these flags are primarily for aesthetics, while others may be essential for
378     enabling certain features on the system.
379     </p>
380    
381 swift 1.1 <ul>
382 neysx 1.23 <li>
383     <b>--<c>no-</c>bootsplash</b>: Activates <e>[or deactivates]</e> support
384     for <uri link="http://www.bootsplash.org/">bootsplash</uri> in the
385     genkernel-built initrd image. The bootsplash feature is supported on a
386     limited number of architectures, and a kernel that supports bootsplash is
387     also required.
388     </li>
389     <li>
390     <b>--<c>no-</c>gensplash</b>: Activates <e>[or deactivates]</e> support for
391     <uri
392     link="http://dev.gentoo.org/~spock/projects/gensplash/">gensplash</uri>
393     support in the genkernel-built initrd image. The gensplash utility is
394     intended to be a replacement for bootsplash, and is designed for use with
395     2.6.x series kernels. To override the default theme used by gensplash, use
396     <b>--gensplash=<c>PreferredTheme</c></b> (where <c>PreferredTheme</c> is
397     the title of one of the directories inside the <path>/etc/splash/</path>
398     directory.
399     </li>
400     <li>
401     <b>--gensplash-res=<c>PreferredResolution</c></b>: This flag allows you to
402     select which splash screen resolutions will be supported in the initrd
403     during the start-up of the system. This is useful for two reasons: First,
404     you are able to select only the splash screen resolution(s) relevant to
405     your system. Second, you avoid the unnecessary increase in the disk space
406     required by initrd (since the initrd does not have to support resolutions
407     that are irrelevant for your system configuration.) However, you may want
408     to omit this flag if the kernel is being compiled for an Installation CD;
409     this allows gensplash support for all possible resolutions.
410     </li>
411     <li>
412     <b>--do-keymap-auto</b>: Force keymap selection during the boot sequence.
413     </li>
414     <li>
415     <b>--lvm2</b>: Includes support for storage using via <uri
416     link="http://sources.redhat.com/lvm2/">Logical Volume Management</uri>
417     (LVM2) from <e>static</e> binaries, if available to the system. Relevant
418     (static) LVM2 binaries are compiled if they are unavailable. Be sure to
419     install the lvm2 package on your system with <c>emerge lvm2</c> before
420     enabling this flag, and review the <uri link="/doc/en/lvm2.xml">Gentoo LVM2
421     Installation</uri> guide.
422     </li>
423     <li>
424     <b>--evms2</b>: Includes support for storage using the <uri
425     link="http://evms.sourceforge.net/">Enterprise Volume Management
426     System</uri> (EVMS2), if available. Be sure to install the evms package on
427     your system with <c>USE=static emerge evms2</c> before using this
428 cam 1.25 (genkernel) flag. <e>(Omitting the </e><c>USE=static</c><e> flag during
429     package installation will fail to include the necessary static
430     binaries.)</e>
431 neysx 1.23 </li>
432     <li>
433     <b>--dmraid</b>: Includes support for <uri
434     link="http://people.redhat.com/~heinzm/sw/dmraid/readme">DMRAID</uri>; the
435     utility which creates RAID mappings using the kernel device-mapper
436     subsystem. DMRAID discovers, activates, deactivates and displays properties
437     of software RAID sets (ATARAID, for example) and contained DOS partitions.
438     </li>
439     <li>
440 nightmorph 1.29 <b>--luks</b>: Includes support for <uri
441     link="http://luks.endorphin.org/">Linux Unified Key Setup</uri> or LUKS.
442     This will allow you to use a device encrypted by LUKS which contains the
443     root filesystem. On the bootloader, you then set that encrypted device as
444     the value of crypt_root (and real_root shall be the unencrypted device LUKS
445     creates).
446     </li>
447     <li>
448 neysx 1.23 <b>--linuxrc=/path/to/your/linuxrc</b>: Specifies a user-created
449 cam 1.25 <e>linuxrc</e> &mdash; a script that is initialized during the start-up
450     stage of the kernel, prior to the actual boot process. (A default linuxrc
451     script should be in the <path>/usr/share/genkernel/</path> directory.) This
452     script allows you to boot into a small, modularized kernel and load the
453     drivers that are needed (as modules) by the system.
454 neysx 1.23 </li>
455     <li>
456     <b>--cachedir=/path/to/alt/dir/</b>: Overrides the default cache location
457     used while compiling the kernel.
458     </li>
459     <li>
460     <b>--tempdir=/path/to/new/tempdir/</b>: Specifies the location of the
461     temporary directory used by genkernel while compiling the kernel.
462     </li>
463     <li>
464     <b>--unionfs</b>: Includes support for the <uri
465     link="http://www.fsl.cs.sunysb.edu/project-unionfs.html">Unification File
466     System</uri> in the initrd image.
467     </li>
468 swift 1.1 </ul>
469    
470     </body>
471     </section>
472     <section>
473 plasmaroo 1.17 <title>Miscellaneous Flags</title>
474 swift 1.1 <body>
475    
476     <p>
477 plasmaroo 1.17 The assortment of flags listed below are supported by genkernel, but do not fit
478     neatly into any of the other categories:
479 swift 1.1 </p>
480    
481     <ul>
482 neysx 1.23 <li>
483     <b>--mountboot</b>: Detects whether or not the <path>/boot/</path>
484     directory needs to be mounted on a separate partition. It will check
485     <path>/etc/fstab</path> script for instructions on how to mount the boot
486     partition on a file system (if needed).
487     </li>
488     <li>
489     <b>--kernname=<c>NickName</c></b>: Allows you to modify the name of the
490     kernel and initrd images in the <path>/boot/</path> directory, so that the
491     images produced are kernel-<c>NickName</c>-version and
492     initramfs-<c>NickName</c>-version.
493     </li>
494 swift 1.1 </ul>
495    
496     </body>
497     </section>
498     <section>
499 plasmaroo 1.17 <title>Possible Actions</title>
500 swift 1.1 <body>
501    
502     <p>
503 plasmaroo 1.17 An action tells genkernel what to build. Currently, the following actions are
504     supported:
505 swift 1.1 </p>
506    
507 plasmaroo 1.17 <ul>
508 neysx 1.23 <li><c>initrd</c>: Only builds the initrd image</li>
509     <li><c>bzImage</c>: Only builds the kernel image</li>
510     <li><c>kernel</c>: Only builds the kernel image and modules</li>
511 cam 1.25 <li>
512     <c>all</c>: Builds all stages &mdash; the initrd, kernel image and modules.
513     </li>
514 plasmaroo 1.17 </ul>
515 swift 1.1
516     <p>
517 plasmaroo 1.17 The last action, <c>all</c>, is recommended for most users since it builds the
518     stages required for a functional kernel. Remember, an <e>action</e> simply
519     tells genkernel what to <e>build</e>, not <e>install</e>.
520 swift 1.1 </p>
521    
522     </body>
523     </section>
524     <section>
525 plasmaroo 1.17 <title>Bootloader Configuration</title>
526 swift 1.1 <body>
527    
528     <p>
529 plasmaroo 1.17 To set up genkernel to work with your bootloader, three or four changes should
530 neysx 1.20 be applied to the bootloader's configuration file:
531 swift 1.1 </p>
532    
533     <ol>
534 neysx 1.23 <li>
535     Add <c>root=/dev/ram0</c> and <c>init=/linuxrc</c> to the kernel parameters
536     passed to the kernel image.
537     </li>
538     <li>
539     Add <c>real_root=/dev/hda3</c>, for example, to the kernel parameters
540     passed to the kernel image, if <path>/dev/hda3</path> contains your root
541     partition.
542     </li>
543     <li>
544     If you are using bootsplash, add a suitable mode line such as
545     <c>vga=0x317</c> to the parameters passed to the kernel and also add
546     <c>splash=verbose</c> or <c>splash=silent</c> depending on the verboseness
547     you require from your bootloader.
548     </li>
549     <li>
550     Add the initrd information as required by the bootloader. Consult the <uri
551 cam 1.24 link="/doc/en/handbook/handbook-x86.xml?part=1&amp;chap=10">Bootloader
552 neysx 1.23 Configuration Chapter</uri> of the Gentoo Handbook for details on how to
553     make your bootloader initrd-aware.
554 swift 1.1 </li>
555     </ol>
556    
557     </body>
558     </section>
559 plasmaroo 1.17 </chapter>
560    
561     <chapter>
562     <title>Configuration Options</title>
563 swift 1.9 <section>
564 plasmaroo 1.17 <title>Editing /etc/genkernel.conf</title>
565 swift 1.9 <body>
566    
567     <p>
568 plasmaroo 1.17 Passing flags to genkernel from the command line can be cumbersome, especially
569     if you have about a dozen flags:
570     </p>
571    
572     <pre caption="Running genkernel (overloaded with flags)">
573 neysx 1.23 # <i>genkernel --debuglevel=5 --no-color --no-mrproper --clean --gensplash \
574     --kerneldir=/path/to/alternate/kernel/sources --install --menuconfig \
575     --kernel-config=/path/to/preferred/configfile --save-config --mountboot all</i>
576 plasmaroo 1.17 </pre>
577    
578 neysx 1.23 <p>
579     Fortunately, there is a configuration file where most of the basic options can
580     be set (or changed) as necessary. What follows is a rundown of the more
581 plasmaroo 1.17 relevant options:
582     </p>
583    
584     <ul>
585 neysx 1.23 <li>
586     <b>MENUCONFIG=<c>[yes|no]</c></b>: This option is equivalent to the
587     <c>--menuconfig</c> flag used by genkernel, which in turn uses the <c>make
588     menuconfig</c> command to invoke a command-line based kernel configuration
589     utility. To invoke the utility automatically during kernel configuration
590     via this script, set this option to 'yes' here; otherwise, choose 'no'.
591     </li>
592     <li>
593     <b>CLEAN=<c>[yes|no]</c></b>: Setting this option to 'yes' is equivalent to
594     the <c>--clean</c> flag used by genkernel, and invokes the <c>make
595     clean</c> command to remove all object files and dependencies from the
596     kernel's source tree. Setting this option to 'no' creates a cascade effect
597     &#8212; it is equivalent to genkernel's <c>--no-clean</c> flag, which
598     disables the <c>make clean</c> command and implies genkernel's
599 cam 1.25 <c>--no-mrproper</c> flag &mdash; essentially nullifying the <c>make
600 neysx 1.23 mrproper</c> command.
601     </li>
602     <li>
603     <b>MRPROPER=<c>[yes|no]</c></b>: Setting this option to 'yes' is equivalent
604     to <c>--mrproper</c> flag used by genkernel, and invokes the <c>make
605     mrproper</c> command, which purges the kernel source tree of any
606     configuration files. Selecting 'no' here is equivalent to genkernel's
607     <c>--no-mrproper</c> flag, which disables the <c>make mrproper</c> command.
608     </li>
609     <li>
610     <b>MOUNTBOOT=<c>[yes|no]</c></b>: Setting this option to 'yes' is
611     equivalent to the <c>--mountboot</c> flag, and automatically mounts the
612     <path>/boot/</path> directory (if needed) at compile time. If the
613     <path>/boot/</path> directory is on a separate partition, consider enabling
614     this option; it will make for one less (essential) step to remember later.
615     </li>
616     <li>
617     <b>SAVE_CONFIG=<c>[yes|no]</c></b>: After configuring the kernel, the
618     selected options are stored as <path>.config</path> in the kernel source
619     tree. This script may be overwritten during the next kernel compilation, or
620     even purged from the kernel source tree. Choosing 'yes' here is equivalent
621     to the <c>--save-config</c> flag, and stores all options selected during
622     kernel configuration as a script in the <path>/etc/kernels/</path>
623     directory. Choosing 'no' preserves the <e>status quo</e>.
624     </li>
625     <li>
626     <b>USECOLOR=<c>[yes|no]</c></b>: Setting this option to 'yes' is equivalent
627     to the <c>--color</c> flag, which colors genkernel's output to ease
628     debugging (when needed.)
629     </li>
630     <li>
631     <b>DEBUGLEVEL=<c>[0|1|2|3|4|5]</c></b>: This option is for adjusting the
632 cam 1.25 verbosity of the output produced by genkernel &mdash; setting this option to
633     '0' with <c>--debuglevel=0</c> will suppress all output produced by
634     genkernel; setting this option to '5' with <c>--debuglevel=5</c> provides
635     the user with all output produced by genkernel.
636 neysx 1.23 </li>
637 plasmaroo 1.17 </ul>
638    
639     <p>
640     By choosing the appropriate options in <path>/etc/genkernel.conf</path>, you
641     can halve the number of flags passed to genkernel from the command line:
642     </p>
643    
644     <pre caption="Running genkernel (with flags), after employing genkernel.conf">
645 cam 1.24 # <i>genkernel --gensplash --kerneldir=/path/to/alternate/kernel/sources \
646 neysx 1.23 --kernel-config=/path/to/preferred/configfile --install all</i>
647 plasmaroo 1.17 </pre>
648    
649     <p>
650     Identical results are obtained from both approaches, but the latter has most of
651     the options stored in a script that can be modified at a later date.
652 swift 1.9 </p>
653    
654     </body>
655     </section>
656 swift 1.1 </chapter>
657    
658     <chapter>
659 plasmaroo 1.17 <title>Network-Booting with genkernel</title>
660 swift 1.1 <section>
661 plasmaroo 1.17 <title>Network Booting from an Installation CD</title>
662     <body>
663    
664     <p>
665     The genkernel utility can build kernel and initrd images that provide support
666 cam 1.24 for network booting, or <e>netboot</e>ing. With any luck, you should be able
667 plasmaroo 1.17 to netboot any recent computer into the environment provided by the
668     Installation CD.
669     </p>
670    
671     <p>
672     The magic lies in genkernel's linuxrc script: it will try to <e>netmount</e>
673     the Installation CD using NFS. From there, <e>the init scripts</e> of the
674     Installation CD can take over, as if the CD was present locally.
675     </p>
676    
677     </body>
678     </section>
679     <section>
680     <title>Building Kernel and Initrd Images with Support for Netbooting</title>
681 swift 1.1 <body>
682    
683     <p>
684 plasmaroo 1.17 To enable support for netbooting, include the following options while
685     configuring the kernel:
686 swift 1.1 </p>
687    
688 plasmaroo 1.17 <warn>
689     Support for netbooting with genkernel is experimental and may contain bugs.
690     </warn>
691    
692     <p>
693     First, the kernel image must include the drivers for your Network Interface
694 plasmaroo 1.18 Cards (NIC). Normally, drivers for such devices will be compiled as modules.
695 alin 1.21 However, it is essential (for netbooting) that you have such drivers compiled
696 plasmaroo 1.18 directly into the kernel image and <b>not</b> as modules.
697 plasmaroo 1.17 </p>
698    
699     <pre caption="Configuring a 2.6.x series kernel to support your NIC driver">
700     Device Drivers --->
701     Networking Support --->
702 cam 1.24 Ethernet (10 or 100Mbit) --->
703     [*] Ethernet (10 or 100Mbit)
704 plasmaroo 1.17 &lt;*&gt; the driver for your network card
705 alin 1.21 <comment>(Be sure to select &lt;*&gt; and not &lt;M&gt;)</comment>
706 plasmaroo 1.17 </pre>
707    
708     <p>
709 neysx 1.23 Secondly, we suggest that you enable <c>IP: kernel level autoconfiguration</c>
710     and the <c>IP: DHCP support</c> options. This avoids an unnecessary layer of
711     complexity since the IP address and the NFS path to the Installation CD can be
712     configured on a DHCP server. Of course, this means the kernel command line
713 cam 1.25 will remain constant for any machine &mdash; which is very important for
714 neysx 1.23 <e>etherbooting</e>.
715 plasmaroo 1.17 </p>
716    
717     <pre caption="Configuring a 2.6.x series kernel to support DHCP">
718     Device Drivers --->
719     Networking Support --->
720 cam 1.24 Networking options
721 plasmaroo 1.17 [*] TCP/IP networking--->
722     [*] IP: kernel level autoconfiguration
723     [*] IP: DHCP support
724     <comment>(These options tell the kernel to send a DHCP request at bootup.)</comment>
725     </pre>
726    
727     <p>
728     Additionally, you should enable SquashFS because most modern Gentoo
729     Installation CDs require it. Support for SquashFS is not included with the
730     generic kernel source tree. To enable SquashFS, apply the necessary patches to
731     the generic kernel source or install <c>gentoo-sources</c>.
732     </p>
733    
734     <pre caption="Configuring the kernel to support SquashFS">
735 cam 1.24 File systems--->
736 plasmaroo 1.17 Miscellaneous filesystems --->
737     [*] SquashFS 2.X - Squashed file system support
738     </pre>
739    
740     <p>
741     Once the compilation process is completed, create a compressed <e>tarball</e>
742     (tar.gz) that contains the kernel's modules. This step is only necessary if
743     your kernel version does not match the kernel image version on the Installation
744     CD.
745     </p>
746    
747     <pre caption="Creating a compressed tarball containing the kernel modules">
748 neysx 1.23 <comment>(Create a tar.gz containing all the modules)</comment>
749     # <i>cd /</i>
750 cam 1.25 # <i>tar -cf /tmp/modules-X.Y.Z.tar.gz /lib/modules/X.Y.Z/</i>
751 plasmaroo 1.17 </pre>
752    
753     <p>
754     Depending on your network boot mechanism, you will need to do some of the
755     following steps:
756     </p>
757    
758     <pre caption="Creating a boot image">
759 neysx 1.23 <comment>(Create an etherboot image)</comment>
760     # <i>emerge mknbi</i>
761     # <i>cd /boot</i>
762     # <i>mkelf-linux -params="root=/dev/ram0 init=/linuxrc ip=dhcp" kernel... initrd... > etherboot.img</i>
763    
764     <comment>(Create a OpenBoot / SPARC64 TFTP image)</comment>
765     # <i>emerge sparc-utils</i>
766     # <i>cd /boot</i>
767     # <i>elftoaout kernel... -o kernel.aout</i>
768     # <i>piggyback64 kernel.aout System.map-... initrd-...</i>
769     # <i>mv kernel.aout openboot.img</i> <comment>(This is the boot image)</comment>
770 plasmaroo 1.17
771 neysx 1.23 <comment>(PXE does not need any more steps, the kernel and initrd can be used as is)</comment>
772 plasmaroo 1.17 </pre>
773    
774     <p>
775     Finally, copy this kernel to your TFTP server. The details are
776     architecture-dependent and are beyond the scope of this guide. Please refer to
777     the documentation for your platform.
778     </p>
779    
780     </body>
781     </section>
782     <section>
783     <title>NFS Setup</title>
784     <body>
785    
786 swift 1.1 <p>
787 plasmaroo 1.17 To setup a NFS share that contains the Installation CD, use the loop device to
788     mount the ISO image and then copy the contents of the CD into the NFS share. As
789     a nice extra, genkernel's initrd scripts will extract all tar.gz files located
790     in the <path>/nfs/livecd/add/</path> directory. All you have to do here is copy
791     the <c>modules-X.Y.Z.tar.gz</c> archive to the <path>/nfs/livecd/add/</path>
792     directory.
793 swift 1.1 </p>
794    
795 plasmaroo 1.17 <pre caption="Preparing the NFS share">
796 nightmorph 1.28 <comment>(This assumes that /nfs/livecd is an exported NFS share)</comment>
797 cam 1.25 # <i>mount /tmp/gentoo-livecd.iso /mnt/cdrom -o loop</i>
798 neysx 1.23 # <i>cp -p /mnt/cdrom /nfs/livecd</i>
799     # <i>umount /mnt/cdrom</i>
800    
801     <comment>(Copy the modules.tar.gz into /add)</comment>
802     # <i>mkdir /nfs/livecd/add</i>
803     # <i>cp /tmp/modules-X.Y.Z.tar.gz /nfs/livecd/add</i>
804 plasmaroo 1.17 </pre>
805    
806 swift 1.1 </body>
807     </section>
808     <section>
809 plasmaroo 1.17 <title>DHCP Setup</title>
810 swift 1.1 <body>
811    
812 plasmaroo 1.17 <p>
813 neysx 1.23 The netboot images will ask your DHCP server for an IP as well as a root-path
814 cam 1.24 parameter. Both can be specified per host using a MAC address to identify
815 neysx 1.23 machines:
816 plasmaroo 1.17 </p>
817    
818     <pre caption="Sample client dhcpd.conf setup">
819     ...
820    
821     host netbootableMachine {
822     hardware ethernet 11:22:33:44:55:66;
823     fixed-address 192.168.1.10;
824     option root-path "192.168.1.2:/nfs/livecd";
825     }
826     <comment># Here, 192.168.1.2 is the NFS server
827     # While 192.168.1.10 will be the IP address of the netbooted machine</comment>
828     ...
829     </pre>
830 swift 1.1
831     </body>
832     </section>
833     <section>
834 plasmaroo 1.17 <title>Netbooting Instructions</title>
835 swift 1.1 <body>
836    
837 plasmaroo 1.17 <p>
838 neysx 1.23 Netbooting itself is again very platform-specific. The important part is to
839     specify the <c>ip=dhcp</c> and <c>init=/linuxrc</c> parameters on the kernel
840     command line, as this will bring up the network interface and tell the initrd
841     scripts to mount the Installation CD via NFS. Here are some platform-specific
842     tips:
843 plasmaroo 1.17 </p>
844    
845     <pre caption="Netbooting Instructions">
846     <comment># Etherboot - insert the etherboot disk into the drive and reboot
847     # The kernel command line was specified when the image was constructed</comment>
848    
849 neysx 1.23 <comment># Sparc64 - Hit Stop-A at the boot prompt</comment>
850 plasmaroo 1.17 ok boot net ip=dhcp init=/linuxrc
851    
852 neysx 1.23 <comment># PXE - Setup pxelinux (part of syslinux),
853     then create a pxelinux.cfg/default along the lines of:</comment>
854 plasmaroo 1.17
855     DEFAULT gentoo
856     TIMEOUT 40
857     PROMPT 1
858    
859     LABEL gentoo
860 neysx 1.23 KERNEL kernel-X.Y.Z
861     APPEND initrd=initrd-X.Y.Z root=/dev/ram0 init=/linuxrc ip=dhcp
862 plasmaroo 1.17 </pre>
863    
864     </body>
865     </section>
866     </chapter>
867    
868     <chapter>
869     <title>Conclusion</title>
870     <section>
871     <title>To Automate or not to Automate?</title>
872     <body>
873 swift 1.1
874 plasmaroo 1.17 <p>
875     The purpose of genkernel is to provide an (easier) alternative to the
876 plasmaroo 1.18 time-tested approach to kernel compilation. As always, you are free to decide
877     on whether or not you want to automate the kernel compilation process.
878 plasmaroo 1.17 </p>
879 swift 1.1
880     </body>
881     </section>
882     </chapter>
883 plasmaroo 1.17
884 swift 1.1 </guide>

  ViewVC Help
Powered by ViewVC 1.1.20