1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
|
<!-- retain these comments for translator revision tracking -->
<!-- $Id$ -->
<sect1 id="kernel-baking"><title>Compiling a New Kernel</title>
<para>
Why would someone want to compile a new kernel? It is often not
necessary since the default kernel shipped with Debian handles most
configurations. Also, Debian often offers several alternative kernels.
So you may want to check first if there is an alternative kernel image
package that better corresponds to your hardware. However, it can be
useful to compile a new kernel in order to:
<itemizedlist>
<listitem><para>
handle special hardware needs, or hardware conflicts with the
pre-supplied kernels
</para></listitem>
<listitem><para>
use options of the kernel which are not supported in the pre-supplied
kernels (such as high memory support)
</para></listitem>
<listitem><para>
optimize the kernel by removing useless drivers to speed up boot time
</para></listitem>
<listitem><para>
create a monolithic instead of a modularized kernel
</para></listitem>
<listitem><para>
run an updated or development kernel
</para></listitem>
<listitem><para>
learn more about linux kernels
</para></listitem>
</itemizedlist>
</para>
<sect2><title>Kernel Image Management</title>
<para>
Don't be afraid to try compiling the kernel. It's fun and profitable.
</para><para>
To compile a kernel the Debian way, you need some packages:
<classname>fakeroot</classname>, <classname>kernel-package</classname>,
<phrase condition="classic-kpkg"><classname>kernel-source-&kernelversion;</classname>
(the most recent version at the time of this writing)</phrase>
<phrase condition="common-kpkg"><classname>linux-source-2.6</classname></phrase>
and a few others which are probably already installed (see
<filename>/usr/share/doc/kernel-package/README.gz</filename> for the
complete list).
</para><para>
This method will make a .deb of your kernel source, and, if you have
non-standard modules, make a synchronized dependent .deb of those
too. It's a better way to manage kernel images;
<filename>/boot</filename> will hold the kernel, the System.map, and a
log of the active config file for the build.
</para><para>
Note that you don't <emphasis>have</emphasis> to compile your kernel
the <quote>Debian way</quote>; but we find that using the packaging system
to manage your kernel is actually safer and easier. In fact, you can get
your kernel sources right from Linus instead of
<phrase condition="classic-kpkg"><classname>kernel-source-&kernelversion;</classname>,</phrase>
<phrase condition="common-kpkg"><classname>linux-source-2.6</classname>,</phrase>
yet still use the <classname>kernel-package</classname> compilation method.
</para><para>
Note that you'll find complete documentation on using
<classname>kernel-package</classname> under
<filename>/usr/share/doc/kernel-package</filename>. This section just
contains a brief tutorial.
</para><para>
Hereafter, we'll assume you have free rein over your machine and will
extract your kernel source to somewhere in your home directory<footnote>
<para>
There are other locations where you can extract kernel sources and build
your custom kernel, but this is easiest as it does not require special
permissions.
</para>
</footnote>. We'll also assume that your kernel version is
&kernelversion;. Make sure you are in the directory to where you want to
unpack the kernel sources, extract them using
<phrase condition="classic-kpkg"><userinput>tar xjf
/usr/src/kernel-source-&kernelversion;.tar.bz2</userinput></phrase>
<phrase condition="common-kpkg"><userinput>tar xjf
/usr/src/linux-source-&kernelversion;.tar.bz2</userinput></phrase>
and change to the directory
<phrase condition="classic-kpkg"><filename>kernel-source-&kernelversion;</filename></phrase>
<phrase condition="common-kpkg"><filename>linux-source-&kernelversion;</filename></phrase>
that will have been created.
</para><para>
Now, you can configure your kernel. Run <userinput>make
xconfig</userinput> if X11 is installed, configured and being run; run
<userinput>make menuconfig</userinput> otherwise (you'll need
<classname>libncurses5-dev</classname> installed). Take the time to read
the online help and choose carefully. When in doubt, it is typically
better to include the device driver (the software which manages
hardware peripherals, such as Ethernet cards, SCSI controllers, and so
on) you are unsure about. Be careful: other options, not related to a
specific hardware, should be left at the default value if you do not
understand them. Do not forget to select <quote>Kernel module loader</quote>
in <quote>Loadable module support</quote> (it is not selected by default).
If not included, your Debian installation will experience problems.
</para><para>
Clean the source tree and reset the <classname>kernel-package</classname>
parameters. To do that, do <userinput>make-kpkg clean</userinput>.
</para><para>
Now, compile the kernel:
<userinput>fakeroot make-kpkg --initrd --revision=custom.1.0 kernel_image</userinput>.
The version number of <quote>1.0</quote> can be changed at will; this is just
a version number that you will use to track your kernel builds.
Likewise, you can put any word you like in place of <quote>custom</quote>
(e.g., a host name). Kernel compilation may take quite a while, depending on
the power of your machine.
</para><para>
Once the compilation is complete, you can install your custom kernel
like any package. As root, do
<phrase condition="classic-kpkg">
<userinput>dpkg -i
../kernel-image-&kernelversion;-<replaceable>subarchitecture</replaceable>_custom.1.0_&architecture;.deb</userinput>.
</phrase>
<phrase condition="common-kpkg">
<userinput>dpkg -i
../linux-image-&kernelversion;-<replaceable>subarchitecture</replaceable>_custom.1.0_&architecture;.deb</userinput>.
</phrase>
The <replaceable>subarchitecture</replaceable> part is an optional
sub-architecture,
<phrase arch="x86"> such as <quote>i586</quote>, </phrase>
depending on what kernel options you set.
<userinput>dpkg -i</userinput> will install the
kernel, along with some other nice supporting files. For instance,
the <filename>System.map</filename> will be properly installed
(helpful for debugging kernel problems), and
<filename>/boot/config-&kernelversion;</filename> will be installed,
containing your current configuration set. Your new
kernel package is also clever enough to automatically update your boot
loader to use the new kernel. If you have created a modules package,
<phrase condition="classic-kpkg">e.g., if you have PCMCIA,</phrase>
you'll need to install that package as well.
</para><para>
It is time to reboot the system: read carefully any warning that the
above step may have produced, then <userinput>shutdown -r now</userinput>.
</para><para>
For more information on Debian kernels and kernel compilation, see the
<ulink url="&url-kernel-handbook;">Debian Linux Kernel Handbook</ulink>.
For more information on <classname>kernel-package</classname>, read
the fine documentation in <filename>/usr/share/doc/kernel-package</filename>.
</para>
</sect2>
</sect1>
|
