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1 <?xml version='1.0' encoding='UTF-8'?>
2 <!DOCTYPE sections SYSTEM "/dtd/book.dtd">
3
4 <!-- The content of this document is licensed under the CC-BY-SA license -->
5 <!-- See http://creativecommons.org/licenses/by-sa/2.5 -->
6
7 <!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/handbook/hb-install-x86+amd64-kernel.xml,v 1.24 2008/05/09 10:33:08 nightmorph Exp $ -->
8
9 <sections>
10
11 <abstract>
12 The Linux kernel is the core of every distribution. This chapter
13 explains how to configure your kernel.
14 </abstract>
15
16 <version>6.3</version>
17 <date>2008-05-19</date>
18
19 <section>
20 <title>Timezone</title>
21 <body>
22
23 <p>
24 You first need to select your timezone so that your system knows where it is
25 located. Look for your timezone in <path>/usr/share/zoneinfo</path>, then copy
26 it to <path>/etc/localtime</path>. Please avoid the
27 <path>/usr/share/zoneinfo/Etc/GMT*</path> timezones as their names do not
28 indicate the expected zones. For instance, <path>GMT-8</path> is in fact
29 GMT+8.
30 </p>
31
32 <pre caption="Setting the timezone information">
33 # <i>ls /usr/share/zoneinfo</i>
34 <comment>(Suppose you want to use GMT)</comment>
35 # <i>cp /usr/share/zoneinfo/GMT /etc/localtime</i>
36 </pre>
37
38 </body>
39 </section>
40 <section>
41 <title>Installing the Sources</title>
42 <subsection>
43 <title>Choosing a Kernel</title>
44 <body>
45
46 <p>
47 The core around which all distributions are built is the Linux kernel. It is the
48 layer between the user programs and your system hardware. Gentoo provides its
49 users several possible kernel sources. A full listing with description is
50 available at the <uri link="/doc/en/gentoo-kernel.xml">Gentoo Kernel
51 Guide</uri>.
52 </p>
53
54 <p>
55 For <keyval id="arch"/>-based systems we have <c>gentoo-sources</c>
56 (kernel source patched for extra features).
57 </p>
58
59 <p>
60 Choose your kernel source and install it using <c>emerge</c>.
61 </p>
62
63 <pre caption="Installing a kernel source">
64 # <i>emerge gentoo-sources</i>
65 </pre>
66
67 <p>
68 When you take a look in <path>/usr/src</path> you should see a symlink called
69 <path>linux</path> pointing to your kernel source. In this case, the installed
70 kernel source points to <c>gentoo-sources-<keyval id="kernel-version"/></c>.
71 Your version may be different, so keep this in mind.
72 </p>
73
74 <pre caption="Viewing the kernel source symlink">
75 # <i>ls -l /usr/src/linux</i>
76 lrwxrwxrwx 1 root root 12 Oct 13 11:04 /usr/src/linux -&gt; linux-<keyval id="kernel-version"/>
77 </pre>
78
79 <p>
80 Now it is time to configure and compile your kernel source. You can use
81 <c>genkernel</c> for this, which will build a generic kernel as used by the
82 Installation CD. We explain the "manual" configuration first though, as it is
83 the best way to optimize your environment.
84 </p>
85
86 <p>
87 If you want to manually configure your kernel, continue now with <uri
88 link="#manual">Default: Manual Configuration</uri>. If you want to use
89 <c>genkernel</c> you should read <uri link="#genkernel">Alternative: Using
90 genkernel</uri> instead.
91 </p>
92
93 </body>
94 </subsection>
95 </section>
96 <section id="manual">
97 <title>Default: Manual Configuration</title>
98 <subsection>
99 <title>Introduction</title>
100 <body>
101
102 <p>
103 Manually configuring a kernel is often seen as the most difficult procedure a
104 Linux user ever has to perform. Nothing is less true -- after configuring a
105 couple of kernels you don't even remember that it was difficult ;)
106 </p>
107
108 <p>
109 However, one thing <e>is</e> true: you must know your system when you start
110 configuring a kernel manually. Most information can be gathered by emerging
111 pciutils (<c>emerge pciutils</c>) which contains <c>lspci</c>. You will now
112 be able to use <c>lspci</c> within the chrooted environment. You may safely
113 ignore any <e>pcilib</e> warnings (like pcilib: cannot open
114 /sys/bus/pci/devices) that <c>lspci</c> throws out. Alternatively, you can run
115 <c>lspci</c> from a <e>non-chrooted</e> environment. The results are the same.
116 You can also run <c>lsmod</c> to see what kernel modules the Installation CD
117 uses (it might provide you with a nice hint on what to enable).
118 </p>
119
120 <p>
121 Now go to your kernel source directory and execute <c>make menuconfig</c>. This
122 will fire up an ncurses-based configuration menu.
123 </p>
124
125 <pre caption="Invoking menuconfig">
126 # <i>cd /usr/src/linux</i>
127 # <i>make menuconfig</i>
128 </pre>
129
130 <p>
131 You will be greeted with several configuration sections. We'll first list some
132 options you must activate (otherwise Gentoo will not function, or not function
133 properly without additional tweaks).
134 </p>
135
136 </body>
137 </subsection>
138 <subsection>
139 <title>Activating Required Options</title>
140 <body>
141
142 <p>
143 Make sure that every driver that is vital to the booting of your system (such as
144 SCSI controller, ...) is compiled <e>in</e> the kernel and not as a module,
145 otherwise your system will not be able to boot completely.
146 </p>
147
148 </body>
149 <body test="func:keyval('arch')='AMD64'">
150
151 <p>
152 We shall then select the exact processor type. The x86_64 kernel maintainer
153 strongly recommends users enable MCE features so that they are able to be
154 notified of any hardware problems. On x86_64, these errors are not printed to
155 <c>dmesg</c> like on other architectures, but to <path>/dev/mcelog</path>. This
156 requires the <c>app-admin/mcelog</c> package. Make sure you select IA32
157 Emulation if you want to be able to run 32-bit programs. Gentoo will install a
158 multilib system (mixed 32-bit/64-bit computing) by default, so you probably
159 want this option.
160 </p>
161
162 <pre caption="Selecting processor type and features">
163 Processor type and features --->
164 [ ] Intel MCE Features
165 [ ] AMD MCE Features
166 Processor family (AMD-Opteron/Athlon64) --->
167 ( ) AMD-Opteron/Athlon64
168 ( ) Intel EM64T
169 ( ) Generic-x86-64
170 Executable file formats / Emulations --->
171 [*] IA32 Emulation
172 </pre>
173
174 </body>
175 <body test="func:keyval('arch')='x86'">
176
177 <p>
178 Now select the correct processor family:
179 </p>
180
181 <pre caption="Selecting correct processor family">
182 Processor type and features ---&gt;
183 <comment>(Change according to your system)</comment>
184 (<i>Athlon/Duron/K7</i>) Processor family
185 </pre>
186
187 </body>
188 <body>
189
190 <p>
191 Now go to <c>File Systems</c> and select support for the filesystems you use.
192 <e>Don't</e> compile them as modules, otherwise your Gentoo system will not be
193 able to mount your partitions. Also select <c>Virtual memory</c> and <c>/proc
194 file system</c>.
195 </p>
196
197 <pre caption="Selecting necessary file systems">
198 File systems ---&gt;
199 Pseudo Filesystems ---&gt;
200 [*] /proc file system support
201 [*] Virtual memory file system support (former shm fs)
202
203 <comment>(Select one or more of the following options as needed by your system)</comment>
204 &lt;*&gt; Reiserfs support
205 &lt;*&gt; Ext3 journalling file system support
206 &lt;*&gt; JFS filesystem support
207 &lt;*&gt; Second extended fs support
208 &lt;*&gt; XFS filesystem support
209 </pre>
210
211 <p>
212 If you are using PPPoE to connect to the Internet or you are using a dial-up
213 modem, you will need the following options in the kernel:
214 </p>
215
216 <pre caption="Selecting PPPoE necessary drivers">
217 Device Drivers ---&gt;
218 Networking Support ---&gt;
219 &lt;*&gt; PPP (point-to-point protocol) support
220 &lt;*&gt; PPP support for async serial ports
221 &lt;*&gt; PPP support for sync tty ports
222 </pre>
223
224 <p>
225 The two compression options won't harm but are not definitely needed, neither
226 does the <c>PPP over Ethernet</c> option, that might only be used by <c>ppp</c>
227 when configured to do kernel mode PPPoE.
228 </p>
229
230 <p>
231 If you require it, don't forget to include support in the kernel for your
232 ethernet card.
233 </p>
234
235 <p test="func:keyval('arch')='x86'">
236 If you have an Intel CPU that supports HyperThreading (tm), or you have a
237 multi-CPU system, you should activate "Symmetric multi-processing support":
238 </p>
239
240 <p test="func:keyval('arch')='AMD64'">
241 If you have a multi-CPU Opteron or a multi-core (e.g. AMD64 X2) system, you
242 should activate "Symmetric multi-processing support":
243 </p>
244
245 <pre caption="Activating SMP support">
246 Processor type and features ---&gt;
247 [*] Symmetric multi-processing support
248 </pre>
249
250 <note>
251 In multi-core systems, each core counts as one processor.
252 </note>
253
254 <p test="func:keyval('arch')='x86'">
255 If you have more than 4GB of RAM, you need to enable "High Memory Support
256 (64G)".
257 </p>
258
259 <p>
260 If you use USB Input Devices (like Keyboard or Mouse) don't forget to enable
261 those as well:
262 </p>
263
264 <pre caption="Activating USB Support for Input Devices">
265 Device Drivers ---&gt;
266 USB Support ---&gt;
267 &lt;*&gt; USB Human Interface Device (full HID) support
268 </pre>
269
270 </body>
271 <body test="func:keyval('arch')='x86'">
272
273 <p>
274 If you want PCMCIA support for your laptop, don't forget to enable
275 support for the PCMCIA card bridge present in your system:
276 </p>
277
278 <pre caption="Enabling PCMCIA support">
279 Bus options (PCI, PCMCIA, EISA, MCA, ISA) ---&gt;
280 PCCARD (PCMCIA/CardBus) support ---&gt;
281 &lt;*&gt; PCCard (PCMCIA/CardBus) support
282 <comment>(select 16 bit if you need support for older PCMCIA cards. Most people want this.)</comment>
283 &lt;*&gt; 16-bit PCMCIA support
284 [*] 32-bit CardBus support
285 <comment>(select the relevant bridges below)</comment>
286 --- PC-card bridges
287 &lt;*&gt; CardBus yenta-compatible bridge support (NEW)
288 &lt;*&gt; Cirrus PD6729 compatible bridge support (NEW)
289 &lt;*&gt; i82092 compatible bridge support (NEW)
290 &lt;*&gt; i82365 compatible bridge support (NEW)
291 &lt;*&gt; Databook TCIC host bridge support (NEW)
292 </pre>
293
294 <p>
295 When you've finished configuring the kernel, continue with <uri
296 link="#compiling">Compiling and Installing</uri>.
297 </p>
298
299 </body>
300 </subsection>
301 <subsection id="compiling">
302 <title>Compiling and Installing</title>
303 <body>
304
305 <p>
306 Now that your kernel is configured, it is time to compile and install it. Exit
307 the configuration and start the compilation process:
308 </p>
309
310 <pre caption="Compiling the kernel">
311 # <i>make &amp;&amp; make modules_install</i>
312 </pre>
313
314 <p>
315 When the kernel has finished compiling, copy the kernel image to
316 <path>/boot</path>. Use whatever name you feel is appropriate for your kernel
317 choice and remember it as you will need it later on when you configure your
318 bootloader. Remember to replace <c><keyval id="kernel-name"/></c> with the
319 name and version of your kernel.
320 </p>
321
322 <pre caption="Installing the kernel">
323 # <i>cp arch/<keyval id="arch-sub"/>/boot/bzImage /boot/<keyval id="kernel-name"/></i>
324 </pre>
325
326 <p>
327 Now continue with <uri link="#kernel_modules">Kernel Modules</uri>.
328 </p>
329
330 </body>
331 </subsection>
332 </section>
333 <section id="genkernel">
334 <title>Alternative: Using genkernel</title>
335 <body>
336
337 <p>
338 If you are reading this section, you have chosen to use our <c>genkernel</c>
339 script to configure your kernel for you.
340 </p>
341
342 <p>
343 Now that your kernel source tree is installed, it's now time to compile your
344 kernel by using our <c>genkernel</c> script to automatically build a kernel for
345 you. <c>genkernel</c> works by configuring a kernel nearly identically to the
346 way our Installation CD kernel is configured. This means that when you use
347 <c>genkernel</c> to build your kernel, your system will generally detect all
348 your hardware at boot-time, just like our Installation CD does. Because
349 genkernel doesn't require any manual kernel configuration, it is an ideal
350 solution for those users who may not be comfortable compiling their own kernels.
351 </p>
352
353 <p>
354 Now, let's see how to use genkernel. First, emerge the genkernel ebuild:
355 </p>
356
357 <pre caption="Emerging genkernel">
358 # <i>emerge genkernel</i>
359 </pre>
360
361 </body>
362 <body test="func:keyval('arch')='x86'">
363
364 <p>
365 Next, copy over the kernel configuration used by the Installation CD to the
366 location where genkernel looks for the default kernel configuration:
367 </p>
368
369 <pre caption="Copying over the Installation CD kernel config">
370 # <i>zcat /proc/config.gz &gt; /usr/share/genkernel/x86/kernel-config-2.6</i>
371 </pre>
372
373 </body>
374 <body>
375
376 <p>
377 Now, compile your kernel sources by running <c>genkernel all</c>. Be aware
378 though, as <c>genkernel</c> compiles a kernel that supports almost all
379 hardware, this compilation will take quite a while to finish!
380 </p>
381
382 <p>
383 Note that, if your boot partition doesn't use ext2 or ext3 as filesystem you
384 might need to manually configure your kernel using <c>genkernel --menuconfig
385 all</c> and add support for your filesystem <e>in</e> the kernel (i.e.
386 <e>not</e> as a module). Users of EVMS2 or LVM2 will probably want to add
387 <c>--evms2</c> or <c>--lvm2</c> as argument as well.
388 </p>
389
390 <pre caption="Running genkernel">
391 # <i>genkernel all</i>
392 </pre>
393
394 <p>
395 Once <c>genkernel</c> completes, a kernel, full set of modules and
396 <e>initial root disk</e> (initrd) will be created. We will use the kernel
397 and initrd when configuring a boot loader later in this document. Write
398 down the names of the kernel and initrd as you will need it when writing
399 the bootloader configuration file. The initrd will be started immediately after
400 booting to perform hardware autodetection (just like on the Installation CD)
401 before your "real" system starts up.
402 </p>
403
404 <pre caption="Checking the created kernel image name and initrd">
405 # <i>ls /boot/kernel* /boot/initramfs*</i>
406 </pre>
407
408 </body>
409 </section>
410 <section id="kernel_modules">
411 <title>Kernel Modules</title>
412
413 <subsection>
414 <include href="hb-install-kernelmodules.xml"/>
415 </subsection>
416
417 </section>
418 </sections>

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