nixpkgs/modules/system/boot/kernel.nix

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{ config, pkgs, ... }:
with pkgs.lib;
let kernel = config.boot.kernelPackages.kernel; in
{
###### interface
options = {
boot.kernelPackages = mkOption {
default = pkgs.linuxPackages;
# We don't want to evaluate all of linuxPackages for the manual
# - some of it might not even evaluate correctly.
defaultText = "pkgs.linuxPackages";
example = "pkgs.linuxPackages_2_6_25";
description = ''
This option allows you to override the Linux kernel used by
NixOS. Since things like external kernel module packages are
tied to the kernel you're using, it also overrides those.
This option is a function that takes Nixpkgs as an argument
(as a convenience), and returns an attribute set containing at
the very least an attribute <varname>kernel</varname>.
Additional attributes may be needed depending on your
configuration. For instance, if you use the NVIDIA X driver,
then it also needs to contain an attribute
<varname>nvidia_x11</varname>.
'';
};
boot.kernelParams = mkOption {
default = [ ];
description = ''
The kernel parameters. If you want to add additional
parameters, it's best to set
<option>boot.extraKernelParams</option>.
'';
};
boot.extraKernelParams = mkOption {
default = [ ];
example = [ "debugtrace" ];
description = "Additional user-defined kernel parameters.";
};
boot.vesa = mkOption {
default = config.boot.kernelPackages.splashutils != null;
example = false;
description = ''
Whether to activate VESA video mode on boot.
'';
};
boot.extraModulePackages = mkOption {
default = [];
# !!! example = [pkgs.aufs pkgs.nvidia_x11];
description = "A list of additional packages supplying kernel modules.";
};
boot.kernelModules = mkOption {
default = [];
description = ''
The set of kernel modules to be loaded in the second stage of
the boot process. Note that modules that are needed to
mount the root file system should be added to
<option>boot.initrd.availableKernelModules</option> or
<option>boot.initrd.kernelModules</option>.
'';
};
boot.initrd.availableKernelModules = mkOption {
default = [];
example = [ "sata_nv" "ext3" ];
description = ''
The set of kernel modules in the initial ramdisk used during the
boot process. This set must include all modules necessary for
mounting the root device. That is, it should include modules
for the physical device (e.g., SCSI drivers) and for the file
system (e.g., ext3). The set specified here is automatically
closed under the module dependency relation, i.e., all
dependencies of the modules list here are included
automatically. The modules listed here are available in the
initrd, but are only loaded on demand (e.g., the ext3 module is
loaded automatically when an ext3 filesystem is mounted, and
modules for PCI devices are loaded when they match the PCI ID
of a device in your system). To force a module to be loaded,
include it in <option>boot.initrd.kernelModules</option>.
'';
};
boot.initrd.kernelModules = mkOption {
default = [];
description = "List of modules that are always loaded by the initrd.";
};
system.modulesTree = mkOption {
internal = true;
default = [];
description = ''
Tree of kernel modules. This includes the kernel, plus modules
built outside of the kernel. Combine these into a single tree of
symlinks because modprobe only supports one directory.
'';
merge = mergeListOption;
# Convert the list of path to only one path.
apply = pkgs.aggregateModules;
};
system.requiredKernelConfig = mkOption {
default = [];
example = literalExample ''
with config.lib.kernelConfig; [
(isYes "MODULES")
(isEnabled "FB_CON_DECOR")
(isEnabled "BLK_DEV_INITRD")
]
'';
internal = true;
type = types.listOf types.attrs;
description = ''
This option allows modules to specify the kernel config options that
must be set (or unset) for the module to work. Please use the
lib.kernelConfig functions to build list elements.
'';
};
};
###### implementation
config = {
system.build = { inherit kernel; };
system.modulesTree = [ kernel ] ++ config.boot.extraModulePackages;
boot.kernelParams =
optionals config.boot.vesa [ "splash=verbose" "vga=0x317" ];
boot.kernelModules = [ "loop" ];
boot.initrd.availableKernelModules =
[ # Note: most of these (especially the SATA/PATA modules)
# shouldn't be included by default since nixos-hardware-scan
# detects them, but I'm keeping them for now for backwards
# compatibility.
# Some SATA/PATA stuff.
"ahci"
"sata_nv"
"sata_via"
"sata_sis"
"sata_uli"
"ata_piix"
"pata_marvell"
# Standard SCSI stuff.
"sd_mod"
"sr_mod"
# Standard IDE stuff.
"ide_cd"
"ide_disk"
"ide_generic"
# Support USB keyboards, in case the boot fails and we only have
# a USB keyboard.
"uhci_hcd"
"ehci_hcd"
"ohci_hcd"
"usbhid"
# Unix domain sockets (needed by udev).
"unix"
# Misc. stuff.
"pcips2" "serio" "atkbd" "xtkbd"
# To wait for SCSI devices to appear.
"scsi_wait_scan"
];
boot.initrd.kernelModules =
[ # For LVM.
"dm_mod"
];
# The Linux kernel >= 2.6.27 provides firmware.
hardware.firmware = [ "${kernel}/lib/firmware" ];
lib.kernelConfig = {
isYes = option: {
assertion = config: config.isYes option;
message = "CONFIG_${option} is not yes!";
configLine = "CONFIG_${option}=y";
};
isNo = option: {
assertion = config: config.isNo option;
message = "CONFIG_${option} is not no!";
configLine = "CONFIG_${option}=n";
};
isModule = option: {
assertion = config: config.isModule option;
message = "CONFIG_${option} is not built as a module!";
configLine = "CONFIG_${option}=m";
};
### Usually you will just want to use these two
# True if yes or module
isEnabled = option: {
assertion = config: config.isEnabled option;
message = "CONFIG_${option} is not enabled!";
configLine = "CONFIG_${option}=y";
};
# True if no or omitted
isDisabled = option: {
assertion = config: config.isDisabled option;
message = "CONFIG_${option} is not disabled!";
configLine = "CONFIG_${option}=n";
};
};
# The config options that all modules can depend upon
system.requiredKernelConfig = with config.lib.kernelConfig; [
(isYes "MODULES")
(isYes "BLK_DEV_INITRD")
];
# nixpkgs kernels are assumed to have all required features
assertions = if config.boot.kernelPackages.kernel ? features then [] else
let cfg = config.boot.kernelPackages.kernel.config; in map (attrs:
{ assertion = attrs.assertion cfg; inherit (attrs) message; }
) config.system.requiredKernelConfig;
};
}