monolith: extract undervolt config

hosts/monolith/default.nix

@@ -23,6 +23,7 @@ in
   imports = [
     (modulesPath + "/installer/scan/not-detected.nix")
     ./partition.nix
+    ./undervolt.nix
   ];
   boot.initrd.availableKernelModules = [
     "nvme"
@@ -66,14 +67,6 @@ in
 
   boot.kernelPackages = pkgs.linuxPackages_6_1;
 
-  programs.corectrl = {
-    enable = true;
-    gpuOverclock = {
-      enable = true;
-      ppfeaturemask = "0xffffffff";
-    };
-  };
-
   fileSystems."/mnt/old" = {
     device = "/dev/disk/by-label/BTRFS_ROOT";
     fsType = "btrfs";

hosts/monolith/undervolt.nix

@@ -0,0 +1,16 @@
+{ pkgs, ... }:
+let
+  undervoltGpu = pkgs.writeShellScript "undervolt-gpu" ''
+    set -xe
+    cd $1
+    test -e pp_od_clk_voltage
+    echo "vo -100" > pp_od_clk_voltage
+    echo "c" > pp_od_clk_voltage
+  '';
+in
+{
+  boot.kernelParams = [ "amdgpu.ppfeaturemask=0xfffd7fff" ];
+  services.udev.extraRules = ''
+    ACTION=="add", SUBSYSTEM=="hwmon", ATTR{name}=="amdgpu", ATTR{power1_cap}="186000000", RUN+="${undervoltGpu} %S%p/device"
+  '';
+}