91 lines
2.9 KiB
Nix
91 lines
2.9 KiB
Nix
{ lib
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, config
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, options
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, ...
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}:
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let
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inherit (builtins) hasAttr;
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inherit (lib) mkIf;
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cfg = config.hardware.cpu.x86.msr;
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opt = options.hardware.cpu.x86.msr;
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defaultGroup = "msr";
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isDefaultGroup = cfg.group == defaultGroup;
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set = "to set for devices of the `msr` kernel subsystem.";
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# Generates `foo=bar` parameters to pass to the kernel.
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# If `module = baz` is passed, generates `baz.foo=bar`.
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# Adds double quotes on demand to handle `foo="bar baz"`.
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kernelParam = { module ? null }: name: value:
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assert lib.asserts.assertMsg (!lib.strings.hasInfix "=" name) "kernel parameter cannot have '=' in name";
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let
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key = (if module == null then "" else module + ".") + name;
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valueString = lib.generators.mkValueStringDefault {} value;
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quotedValueString = if lib.strings.hasInfix " " valueString
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then lib.strings.escape ["\""] valueString
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else valueString;
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in "${key}=${quotedValueString}";
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msrKernelParam = kernelParam { module = "msr"; };
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in
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{
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options.hardware.cpu.x86.msr = with lib.options; with lib.types; {
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enable = mkEnableOption "the `msr` (Model-Specific Registers) kernel module and configure `udev` rules for its devices (usually `/dev/cpu/*/msr`)";
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owner = mkOption {
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type = str;
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default = "root";
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example = "nobody";
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description = "Owner ${set}";
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};
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group = mkOption {
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type = str;
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default = defaultGroup;
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example = "nobody";
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description = "Group ${set}";
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};
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mode = mkOption {
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type = str;
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default = "0640";
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example = "0660";
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description = "Mode ${set}";
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};
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settings = mkOption {
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type = submodule {
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freeformType = attrsOf (oneOf [ bool int str ]);
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options.allow-writes = mkOption {
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type = nullOr (enum ["on" "off"]);
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default = null;
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description = "Whether to allow writes to MSRs (`\"on\"`) or not (`\"off\"`).";
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};
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};
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default = {};
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description = "Parameters for the `msr` kernel module.";
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};
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};
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config = mkIf cfg.enable {
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assertions = [
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{
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assertion = hasAttr cfg.owner config.users.users;
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message = "Owner '${cfg.owner}' set in `${opt.owner}` is not configured via `${options.users.users}.\"${cfg.owner}\"`.";
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}
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{
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assertion = isDefaultGroup || (hasAttr cfg.group config.users.groups);
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message = "Group '${cfg.group}' set in `${opt.group}` is not configured via `${options.users.groups}.\"${cfg.group}\"`.";
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}
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];
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boot = {
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kernelModules = [ "msr" ];
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kernelParams = lib.attrsets.mapAttrsToList msrKernelParam (lib.attrsets.filterAttrs (_: value: value != null) cfg.settings);
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};
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users.groups.${cfg.group} = mkIf isDefaultGroup { };
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services.udev.extraRules = ''
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SUBSYSTEM=="msr", OWNER="${cfg.owner}", GROUP="${cfg.group}", MODE="${cfg.mode}"
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'';
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};
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meta = with lib; {
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maintainers = with maintainers; [ lorenzleutgeb ];
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};
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}
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