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Diffstat (limited to 'nixos/doc/manual/configuration/linux-kernel.xml')
| -rw-r--r-- | nixos/doc/manual/configuration/linux-kernel.xml | 153 |
1 files changed, 111 insertions, 42 deletions
diff --git a/nixos/doc/manual/configuration/linux-kernel.xml b/nixos/doc/manual/configuration/linux-kernel.xml index ffd7b354efe1..f4d697c42dbd 100644 --- a/nixos/doc/manual/configuration/linux-kernel.xml +++ b/nixos/doc/manual/configuration/linux-kernel.xml @@ -3,29 +3,29 @@ xmlns:xi="http://www.w3.org/2001/XInclude" version="5.0" xml:id="sec-kernel-config"> - -<title>Linux Kernel</title> - -<para>You can override the Linux kernel and associated packages using -the option <option>boot.kernelPackages</option>. For instance, this -selects the Linux 3.10 kernel: + <title>Linux Kernel</title> + <para> + You can override the Linux kernel and associated packages using the option + <option>boot.kernelPackages</option>. For instance, this selects the Linux + 3.10 kernel: <programlisting> -boot.kernelPackages = pkgs.linuxPackages_3_10; +<xref linkend="opt-boot.kernelPackages"/> = pkgs.linuxPackages_3_10; </programlisting> -Note that this not only replaces the kernel, but also packages that -are specific to the kernel version, such as the NVIDIA video drivers. -This ensures that driver packages are consistent with the -kernel.</para> - -<para>The default Linux kernel configuration should be fine for most users. You can see the configuration of your current kernel with the following command: + Note that this not only replaces the kernel, but also packages that are + specific to the kernel version, such as the NVIDIA video drivers. This + ensures that driver packages are consistent with the kernel. + </para> + <para> + The default Linux kernel configuration should be fine for most users. You can + see the configuration of your current kernel with the following command: <programlisting> -cat /proc/config.gz | gunzip +zcat /proc/config.gz </programlisting> -If you want to change the kernel configuration, you can use the -<option>packageOverrides</option> feature (see <xref -linkend="sec-customising-packages" />). For instance, to enable -support for the kernel debugger KGDB: - + If you want to change the kernel configuration, you can use the + <option>packageOverrides</option> feature (see + <xref +linkend="sec-customising-packages" />). For instance, to enable support + for the kernel debugger KGDB: <programlisting> nixpkgs.config.packageOverrides = pkgs: { linux_3_4 = pkgs.linux_3_4.override { @@ -36,34 +36,103 @@ nixpkgs.config.packageOverrides = pkgs: }; }; </programlisting> - -<varname>extraConfig</varname> takes a list of Linux kernel -configuration options, one per line. The name of the option should -not include the prefix <literal>CONFIG_</literal>. The option value -is typically <literal>y</literal>, <literal>n</literal> or -<literal>m</literal> (to build something as a kernel module).</para> - -<para>Kernel modules for hardware devices are generally loaded -automatically by <command>udev</command>. You can force a module to -be loaded via <option>boot.kernelModules</option>, e.g. + <varname>extraConfig</varname> takes a list of Linux kernel configuration + options, one per line. The name of the option should not include the prefix + <literal>CONFIG_</literal>. The option value is typically + <literal>y</literal>, <literal>n</literal> or <literal>m</literal> (to build + something as a kernel module). + </para> + <para> + Kernel modules for hardware devices are generally loaded automatically by + <command>udev</command>. You can force a module to be loaded via + <xref linkend="opt-boot.kernelModules"/>, e.g. <programlisting> -boot.kernelModules = [ "fuse" "kvm-intel" "coretemp" ]; +<xref linkend="opt-boot.kernelModules"/> = [ "fuse" "kvm-intel" "coretemp" ]; </programlisting> -If the module is required early during the boot (e.g. to mount the -root file system), you can use -<option>boot.initrd.extraKernelModules</option>: + If the module is required early during the boot (e.g. to mount the root file + system), you can use <xref linkend="opt-boot.initrd.kernelModules"/>: <programlisting> -boot.initrd.extraKernelModules = [ "cifs" ]; +<xref linkend="opt-boot.initrd.kernelModules"/> = [ "cifs" ]; </programlisting> -This causes the specified modules and their dependencies to be added -to the initial ramdisk.</para> - -<para>Kernel runtime parameters can be set through -<option>boot.kernel.sysctl</option>, e.g. + This causes the specified modules and their dependencies to be added to the + initial ramdisk. + </para> + <para> + Kernel runtime parameters can be set through + <xref linkend="opt-boot.kernel.sysctl"/>, e.g. <programlisting> -boot.kernel.sysctl."net.ipv4.tcp_keepalive_time" = 120; +<xref linkend="opt-boot.kernel.sysctl"/>."net.ipv4.tcp_keepalive_time" = 120; </programlisting> -sets the kernel’s TCP keepalive time to 120 seconds. To see the -available parameters, run <command>sysctl -a</command>.</para> + sets the kernel’s TCP keepalive time to 120 seconds. To see the available + parameters, run <command>sysctl -a</command>. + </para> + <section> + <title>Customize your kernel</title> + + <para> + The first step before compiling the kernel is to generate an appropriate + <literal>.config</literal> configuration. Either you pass your own config via + the <literal>configfile</literal> setting of <literal>linuxManualConfig</literal>: + <screen><![CDATA[ + custom-kernel = super.linuxManualConfig { + inherit (super) stdenv hostPlatform; + inherit (linux_4_9) src; + version = "${linux_4_9.version}-custom"; + + configfile = /home/me/my_kernel_config; + allowImportFromDerivation = true; + }; + ]]></screen> + +You can edit the config with this snippet (by default <command>make menuconfig</command> won't work + out of the box on nixos): + <screen><![CDATA[ + nix-shell -E 'with import <nixpkgs> {}; kernelToOverride.overrideAttrs (o: {nativeBuildInputs=o.nativeBuildInputs ++ [ pkgconfig ncurses ];})' + ]]></screen> + + + or you can let nixpkgs generate the configuration. + Nixpkgs generates it via answering the interactive kernel utility <command>make config</command>. + The answers depend on parameters passed to <filename>pkgs/os-specific/linux/kernel/generic.nix</filename> + (which you can influence by overriding <literal>extraConfig, autoModules, modDirVersion, preferBuiltin, extraConfig</literal>). +<screen><![CDATA[ + + mptcp93.override ({ + name="mptcp-local"; + + ignoreConfigErrors = true; + autoModules = false; + kernelPreferBuiltin = true; + + enableParallelBuilding = true; + + extraConfig = '' + DEBUG_KERNEL y + FRAME_POINTER y + KGDB y + KGDB_SERIAL_CONSOLE y + DEBUG_INFO y + ''; + }); + ]]></screen> + </para> + </section> + <section> + <title>Developing kernel modules</title> + + <para> + When developing kernel modules it's often convenient to run edit-compile-run + loop as quickly as possible. See below snippet as an example of developing + <literal>mellanox</literal> drivers. + </para> +<screen><![CDATA[ +$ nix-build '<nixpkgs>' -A linuxPackages.kernel.dev +$ nix-shell '<nixpkgs>' -A linuxPackages.kernel +$ unpackPhase +$ cd linux-* +$ make -C $dev/lib/modules/*/build M=$(pwd)/drivers/net/ethernet/mellanox modules +# insmod ./drivers/net/ethernet/mellanox/mlx5/core/mlx5_core.ko +]]></screen> + </section> </chapter> |