feat: add musnix for realtime audio

flake.lock

@@ -625,6 +625,26 @@
         "type": "github"
       }
     },
+    "musnix": {
+      "inputs": {
+        "nixpkgs": [
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1735772949,
+        "narHash": "sha256-lvee0rhKTpJEDl1SC4F3Kvz88snOU8OMTJBsPH1pVBo=",
+        "owner": "musnix",
+        "repo": "musnix",
+        "rev": "86ef22cbdd7551ef325bce88143be9f37da64c26",
+        "type": "github"
+      },
+      "original": {
+        "owner": "musnix",
+        "repo": "musnix",
+        "type": "github"
+      }
+    },
     "nix-darwin": {
       "inputs": {
         "nixpkgs": [
@@ -887,6 +907,7 @@
         "homebrew-cask": "homebrew-cask",
         "homebrew-core": "homebrew-core",
         "lanzaboote": "lanzaboote",
+        "musnix": "musnix",
         "nix-darwin": "nix-darwin",
         "nix-flatpak": "nix-flatpak",
         "nix-homebrew": "nix-homebrew",

flake.nix

@@ -102,6 +102,11 @@
     };
 
     zenTyp.url = "github:youwen5/zen.typ";
+
+    musnix = {
+      url = "github:musnix/musnix";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
   };
 
   outputs =
@@ -171,6 +176,7 @@
               inputs.nixos-wsl.nixosModules.default
               inputs.stylix.nixosModules.stylix
               inputs.agenix.nixosModules.age
+              inputs.musnix.nixosModules.musnix
               ./modules/default.nix
               ./overlays
               (

modules/linux/audio-prod/default.nix

@@ -6,25 +6,53 @@
 }:
 let
   cfg = config.liminalOS.system.audio.prod;
+  forAllUsers = lib.genAttrs cfg.realtimeAudioUsers;
 in
 {
-  options.liminalOS.system.audio.prod.enable = lib.mkEnableOption "audio production";
-
-  config = lib.mkIf cfg.enable {
-    liminalOS = {
-      programs.wine.enable = true;
-      system.audio.enable = true;
+  options.liminalOS.system.audio.prod = {
+    enable = lib.mkEnableOption "audio production";
+    realtimeAudioUsers = lib.mkOption {
+      type = lib.types.listOf lib.types.str;
+      default = [ ];
+      description = ''
+        List of users to add to the audio group for realtime capabilities.
+      '';
+    };
   };
 
-    environment.systemPackages = with pkgs; [
-      reaper
-      yabridge
-      yabridgectl
-      alsa-scarlett-gui
-    ];
-
-    liminalOS.config.extraUnfreePackages = lib.mkIf config.liminalOS.config.allowUnfree [
+  config = {
+    liminalOS = lib.mkIf cfg.enable {
+      programs.wine.enable = true;
+      system.audio.enable = true;
+      config.extraUnfreePackages = lib.mkIf config.liminalOS.config.allowUnfree [
         "reaper"
       ];
     };
+
+    environment.systemPackages = lib.mkIf cfg.enable (
+      (with pkgs; [
+        yabridge
+        yabridgectl
+        alsa-scarlett-gui
+      ])
+      ++ (lib.optionals config.liminalOS.config.allowUnfree [
+        pkgs.reaper
+      ])
+    );
+
+    musnix.enable = cfg.enable;
+    # PREEMPT_RT is merged into master
+    musnix.kernel.realtime = false;
+
+    musnix.das_watchdog.enable = cfg.enable;
+    musnix.alsaSeq.enable = cfg.enable;
+    musnix.rtcqs.enable = cfg.enable;
+    users.users = forAllUsers (_: {
+      extraGroups = [ "audio" ];
+    });
+
+    boot.kernelParams = lib.mkIf cfg.enable [
+      "threadirqs"
+    ];
+  };
 }

reference/hosts/adrastea/configuration.nix

@@ -20,6 +20,7 @@
     formFactor = "desktop";
     system = {
       audio.prod.enable = true;
+      audio.prod.realtimeAudioUsers = [ "youwen" ];
       networking = {
         firewallPresets.vite = true;
         cloudflareNameservers.enable = true;

reference/hosts/demeter/configuration.nix

@@ -20,6 +20,7 @@
     formFactor = "desktop";
     system = {
       audio.prod.enable = true;
+      audio.prod.realtimeAudioUsers = [ "youwen" ];
       networking = {
         firewallPresets.vite = true;
         cloudflareNameservers.enable = true;