spec

systems/aarch64-linux/macbook-pro-nixos/default.nix

@@ -113,6 +113,8 @@
     };
   };
 
+  specialisation.asahi-fairydust.configuration = import ./specialisations/asahi-fairydust.nix;
+
   nixpkgs.config.allowUnsupportedSystem = true;
 
   virtualisation = {

systems/aarch64-linux/macbook-pro-nixos/specialisations/asahi-fairydust.nix

@@ -0,0 +1,25 @@
+{
+  lib,
+  pkgs,
+  ...
+}:
+{
+  # Override the Asahi kernel source and version by setting boot.kernelPackages
+  # directly.  The nixos-apple-silicon module would normally set this from
+  # linux-asahi via the overlay, but we bypass that here and use linuxPackagesFor
+  # with the kernel overridden in place.  lib.mkOverride 90 beats the module's
+  # lib.mkDefault (priority 1000) but loses to explicit user overrides.
+  boot.kernelPackages = lib.mkOverride 90 (
+    pkgs.linuxPackagesFor (
+      pkgs.linux-asahi.kernel.overrideAttrs (_: {
+        version = "6.18.10";
+        src = pkgs.fetchFromGitHub {
+          owner = "AsahiLinux";
+          repo = "linux";
+          rev = "61b6e714dd19b7bee1c0e6ec4234199e640c2932";
+          hash = "sha256-5eAgJTKcRdjEFzHDSrh/XReaT6Db9YN2RN1SwOs28NE=";
+        };
+      })
+    )
+  );
+}