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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 1.33 2010/07/17 20:18:20 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>7.5</version>
17 <date>2010-07-17</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 this option is
159 required.
160 </p>
161
162 <note>
163 If you plan to use a non-multilib profile (for a pure 64-bit system), then you
164 don't have to select IA32 Emulation support. However, you'll also need to follow
165 the <uri link="?part=1&amp;chap=6#doc_chap2_sect2">instructions</uri> for
166 switching to a <uri link="/doc/en/gentoo-amx64-faq.xml">non-multilib
167 profile</uri>, as well as choosing the correct <uri
168 link="?part=1&amp;chap=10#doc_chap2_sect2">bootloader</uri>.
169 </note>
170
171 <pre caption="Selecting processor type and features">
172 Processor type and features --->
173 [ ] Machine Check / overheating reporting
174 [ ] Intel MCE Features
175 [ ] AMD MCE Features
176 Processor family (AMD-Opteron/Athlon64) --->
177 ( ) Opteron/Athlon64/Hammer/K8
178 ( ) Intel P4 / older Netburst based Xeon
179 ( ) Core 2/newer Xeon
180 ( ) Intel Atom
181 ( ) Generic-x86-64
182 Executable file formats / Emulations --->
183 [*] IA32 Emulation
184 </pre>
185
186 </body>
187 <body test="func:keyval('arch')='x86'">
188
189 <p>
190 Now select the correct processor family:
191 </p>
192
193 <pre caption="Selecting correct processor family">
194 Processor type and features ---&gt;
195 <comment>(Change according to your system)</comment>
196 (<i>Athlon/Duron/K7</i>) Processor family
197 </pre>
198
199 </body>
200 <body>
201
202 <p>
203 Now go to <c>File Systems</c> and select support for the filesystems you use.
204 <e>Don't</e> compile them as modules, otherwise your Gentoo system will not be
205 able to mount your partitions. Also select <c>Virtual memory</c> and <c>/proc
206 file system</c>.
207 </p>
208
209 <pre caption="Selecting necessary file systems">
210 File systems ---&gt;
211 Pseudo Filesystems ---&gt;
212 [*] /proc file system support
213 [*] Virtual memory file system support (former shm fs)
214
215 <comment>(Select one or more of the following options as needed by your system)</comment>
216 &lt;*&gt; Reiserfs support
217 &lt;*&gt; Ext3 journalling file system support
218 &lt;*&gt; JFS filesystem support
219 &lt;*&gt; Second extended fs support
220 &lt;*&gt; XFS filesystem support
221 </pre>
222
223 <p>
224 If you are using PPPoE to connect to the Internet or you are using a dial-up
225 modem, you will need the following options in the kernel:
226 </p>
227
228 <pre caption="Selecting PPPoE necessary drivers">
229 Device Drivers ---&gt;
230 Networking Support ---&gt;
231 &lt;*&gt; PPP (point-to-point protocol) support
232 &lt;*&gt; PPP support for async serial ports
233 &lt;*&gt; PPP support for sync tty ports
234 </pre>
235
236 <p>
237 The two compression options won't harm but are not definitely needed, neither
238 does the <c>PPP over Ethernet</c> option, that might only be used by <c>ppp</c>
239 when configured to do kernel mode PPPoE.
240 </p>
241
242 <p>
243 If you require it, don't forget to include support in the kernel for your
244 ethernet card.
245 </p>
246
247 <p test="func:keyval('arch')='x86'">
248 If you have an Intel CPU that supports HyperThreading (tm), or you have a
249 multi-CPU system, you should activate "Symmetric multi-processing support":
250 </p>
251
252 <p test="func:keyval('arch')='AMD64'">
253 If you have a multi-CPU Opteron or a multi-core (e.g. AMD64 X2) system, you
254 should activate "Symmetric multi-processing support":
255 </p>
256
257 <pre caption="Activating SMP support">
258 Processor type and features ---&gt;
259 [*] Symmetric multi-processing support
260 </pre>
261
262 <note>
263 In multi-core systems, each core counts as one processor.
264 </note>
265
266 <p test="func:keyval('arch')='x86'">
267 If you have more than 4GB of RAM, you need to enable "High Memory Support
268 (64G)".
269 </p>
270
271 <p>
272 If you use USB Input Devices (like Keyboard or Mouse) don't forget to enable
273 those as well:
274 </p>
275
276 <pre caption="Activating USB Support for Input Devices">
277 Device Drivers ---&gt;
278 [*] HID Devices ---&gt;
279 &lt;*&gt; USB Human Interface Device (full HID) support
280 </pre>
281
282 </body>
283 <body test="func:keyval('arch')='x86'">
284
285 <p>
286 If you want PCMCIA support for your laptop, don't forget to enable
287 support for the PCMCIA card bridge present in your system:
288 </p>
289
290 <pre caption="Enabling PCMCIA support">
291 Bus options (PCI, PCMCIA, EISA, MCA, ISA) ---&gt;
292 PCCARD (PCMCIA/CardBus) support ---&gt;
293 &lt;*&gt; PCCard (PCMCIA/CardBus) support
294 <comment>(select 16 bit if you need support for older PCMCIA cards. Most people want this.)</comment>
295 &lt;*&gt; 16-bit PCMCIA support
296 [*] 32-bit CardBus support
297 <comment>(select the relevant bridges below)</comment>
298 --- PC-card bridges
299 &lt;*&gt; CardBus yenta-compatible bridge support (NEW)
300 &lt;*&gt; Cirrus PD6729 compatible bridge support (NEW)
301 &lt;*&gt; i82092 compatible bridge support (NEW)
302 &lt;*&gt; i82365 compatible bridge support (NEW)
303 &lt;*&gt; Databook TCIC host bridge support (NEW)
304 </pre>
305
306 <p>
307 When you've finished configuring the kernel, continue with <uri
308 link="#compiling">Compiling and Installing</uri>.
309 </p>
310
311 </body>
312 </subsection>
313 <subsection id="compiling">
314 <title>Compiling and Installing</title>
315 <body>
316
317 <p>
318 Now that your kernel is configured, it is time to compile and install it. Exit
319 the configuration and start the compilation process:
320 </p>
321
322 <pre caption="Compiling the kernel">
323 # <i>make &amp;&amp; make modules_install</i>
324 </pre>
325
326 <p>
327 When the kernel has finished compiling, copy the kernel image to
328 <path>/boot</path>. Use whatever name you feel is appropriate for your kernel
329 choice and remember it as you will need it later on when you configure your
330 bootloader. Remember to replace <c><keyval id="kernel-name"/></c> with the
331 name and version of your kernel.
332 </p>
333
334 <pre caption="Installing the kernel">
335 # <i>cp arch/<keyval id="arch-sub"/>/boot/bzImage /boot/<keyval id="kernel-name"/></i>
336 </pre>
337
338 <p>
339 Now continue with <uri link="#kernel_modules">Kernel Modules</uri>.
340 </p>
341
342 </body>
343 </subsection>
344 </section>
345 <section id="genkernel">
346 <title>Alternative: Using genkernel</title>
347 <body>
348
349 <p>
350 If you are reading this section, you have chosen to use our <c>genkernel</c>
351 script to configure your kernel for you.
352 </p>
353
354 <p>
355 Now that your kernel source tree is installed, it's now time to compile your
356 kernel by using our <c>genkernel</c> script to automatically build a kernel for
357 you. <c>genkernel</c> works by configuring a kernel nearly identically to the
358 way our Installation CD kernel is configured. This means that when you use
359 <c>genkernel</c> to build your kernel, your system will generally detect all
360 your hardware at boot-time, just like our Installation CD does. Because
361 genkernel doesn't require any manual kernel configuration, it is an ideal
362 solution for those users who may not be comfortable compiling their own kernels.
363 </p>
364
365 <p>
366 Now, let's see how to use genkernel. First, emerge the genkernel ebuild:
367 </p>
368
369 <pre caption="Emerging genkernel">
370 # <i>emerge genkernel</i>
371 </pre>
372
373 <p>
374 Next, copy over the kernel configuration used by the Installation CD to the
375 location where genkernel looks for the default kernel configuration:
376 </p>
377
378 <pre test="func:keyval('arch')='x86'" caption="Copying over the Installation CD kernel config">
379 # <i>zcat /proc/config.gz &gt; /usr/share/genkernel/arch/x86/kernel-config</i>
380 </pre>
381
382 <pre test="func:keyval('arch')='AMD64'" caption="Copying over the Installation CD kernel config">
383 # <i>zcat /proc/config.gz &gt; /usr/share/genkernel/arch/x86_64/kernel-config</i>
384 </pre>
385
386 <p>
387 Now, compile your kernel sources by running <c>genkernel all</c>. Be aware
388 though, as <c>genkernel</c> compiles a kernel that supports almost all
389 hardware, this compilation will take quite a while to finish!
390 </p>
391
392 <p>
393 Note that, if your boot partition doesn't use ext2 or ext3 as filesystem you
394 might need to manually configure your kernel using <c>genkernel --menuconfig
395 all</c> and add support for your filesystem <e>in</e> the kernel (i.e.
396 <e>not</e> as a module). Users of EVMS2 or LVM2 will probably want to add
397 <c>--evms2</c> or <c>--lvm2</c> as arguments as well.
398 </p>
399
400 <pre caption="Running genkernel">
401 # <i>genkernel all</i>
402 </pre>
403
404 <p>
405 Once <c>genkernel</c> completes, a kernel, full set of modules and
406 <e>initial root disk</e> (initrd) will be created. We will use the kernel
407 and initrd when configuring a boot loader later in this document. Write
408 down the names of the kernel and initrd as you will need it when writing
409 the bootloader configuration file. The initrd will be started immediately after
410 booting to perform hardware autodetection (just like on the Installation CD)
411 before your "real" system starts up.
412 </p>
413
414 <pre caption="Checking the created kernel image name and initrd">
415 # <i>ls /boot/kernel* /boot/initramfs*</i>
416 </pre>
417
418 </body>
419 </section>
420 <section id="kernel_modules">
421 <title>Kernel Modules</title>
422
423 <subsection>
424 <include href="hb-install-kernelmodules.xml"/>
425 </subsection>
426
427 </section>
428 </sections>

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