@@ -1,85 +0,0 @@
1−<section xmlns="http://docbook.org/ns/docbook"
2− xmlns:xlink="http://www.w3.org/1999/xlink"
3− xml:id="sec-linux-kernel">
4− <title>Linux kernel</title>
5−
6− <para>
7− The Nix expressions to build the Linux kernel are in <link
8−xlink:href="https://github.com/NixOS/nixpkgs/blob/master/pkgs/os-specific/linux/kernel"><filename>pkgs/os-specific/linux/kernel</filename></link>.
9− </para>
10−
11− <para>
12− The function that builds the kernel has an argument <varname>kernelPatches</varname> which should be a list of <literal>{name, patch, extraConfig}</literal> attribute sets, where <varname>name</varname> is the name of the patch (which is included in the kernel’s <varname>meta.description</varname> attribute), <varname>patch</varname> is the patch itself (possibly compressed), and <varname>extraConfig</varname> (optional) is a string specifying extra options to be concatenated to the kernel configuration file (<filename>.config</filename>).
13− </para>
14−
15− <para>
16− The kernel derivation exports an attribute <varname>features</varname> specifying whether optional functionality is or isn’t enabled. This is used in NixOS to implement kernel-specific behaviour. For instance, if the kernel has the <varname>iwlwifi</varname> feature (i.e. has built-in support for Intel wireless chipsets), then NixOS doesn’t have to build the external <varname>iwlwifi</varname> package:
17−<programlisting>
18−modulesTree = [kernel]
19− ++ pkgs.lib.optional (!kernel.features ? iwlwifi) kernelPackages.iwlwifi
20− ++ ...;
21−</programlisting>
22− </para>
23−
24− <para>
25− How to add a new (major) version of the Linux kernel to Nixpkgs:
26− <orderedlist>
27− <listitem>
28− <para>
29− Copy the old Nix expression (e.g. <filename>linux-2.6.21.nix</filename>) to the new one (e.g. <filename>linux-2.6.22.nix</filename>) and update it.
30− </para>
31− </listitem>
32− <listitem>
33− <para>
34− Add the new kernel to <filename>all-packages.nix</filename> (e.g., create an attribute <varname>kernel_2_6_22</varname>).
35− </para>
36− </listitem>
37− <listitem>
38− <para>
39− Now we’re going to update the kernel configuration. First unpack the kernel. Then for each supported platform (<literal>i686</literal>, <literal>x86_64</literal>, <literal>uml</literal>) do the following:
40− <orderedlist>
41− <listitem>
42− <para>
43− Make an copy from the old config (e.g. <filename>config-2.6.21-i686-smp</filename>) to the new one (e.g. <filename>config-2.6.22-i686-smp</filename>).
44− </para>
45− </listitem>
46− <listitem>
47− <para>
48− Copy the config file for this platform (e.g. <filename>config-2.6.22-i686-smp</filename>) to <filename>.config</filename> in the kernel source tree.
49− </para>
50− </listitem>
51− <listitem>
52− <para>
53− Run <literal>make oldconfig ARCH=<replaceable>{i386,x86_64,um}</replaceable></literal> and answer all questions. (For the uml configuration, also add <literal>SHELL=bash</literal>.) Make sure to keep the configuration consistent between platforms (i.e. don’t enable some feature on <literal>i686</literal> and disable it on <literal>x86_64</literal>).
54− </para>
55− </listitem>
56− <listitem>
57− <para>
58− If needed you can also run <literal>make menuconfig</literal>:
59−<screen>
60−<prompt>$ </prompt>nix-env -i ncurses
61−<prompt>$ </prompt>export NIX_CFLAGS_LINK=-lncurses
62−<prompt>$ </prompt>make menuconfig ARCH=<replaceable>arch</replaceable></screen>
63− </para>
64− </listitem>
65− <listitem>
66− <para>
67− Copy <filename>.config</filename> over the new config file (e.g. <filename>config-2.6.22-i686-smp</filename>).
68− </para>
69− </listitem>
70− </orderedlist>
71− </para>
72− </listitem>
73− <listitem>
74− <para>
75− Test building the kernel: <literal>nix-build -A kernel_2_6_22</literal>. If it compiles, ship it! For extra credit, try booting NixOS with it.
76− </para>
77− </listitem>
78− <listitem>
79− <para>
80− It may be that the new kernel requires updating the external kernel modules and kernel-dependent packages listed in the <varname>linuxPackagesFor</varname> function in <filename>all-packages.nix</filename> (such as the NVIDIA drivers, AUFS, etc.). If the updated packages aren’t backwards compatible with older kernels, you may need to keep the older versions around.
81− </para>
82− </listitem>
83− </orderedlist>
84− </para>
85−</section>