feat: add installer for apple-set-os-loader-installer

apple/t2/apple-set-os-loader-installer.nix

@@ -0,0 +1,41 @@
+{ config, pkgs, ... }:
+let
+  apple-set-os-loader-installer = pkgs.stdenv.mkDerivation rec {
+    name = "apple-set-os-loader-installer-1.0";
+    src = pkgs.fetchFromGitHub {
+      owner = "Redecorating";
+      repo = "apple_set_os-loader";
+      rev = "r33.9856dc4";
+      sha256 = "hvwqfoF989PfDRrwU0BMi69nFjPeOmSaD6vR6jIRK2Y=";
+    };
+    buildInputs = [ pkgs.gnu-efi ];
+    buildPhase = ''
+      substituteInPlace Makefile --replace "/usr" '$(GNU_EFI)'
+      export GNU_EFI=${pkgs.gnu-efi}
+      make
+    '';
+    installPhase = ''
+      install -D bootx64_silent.efi $out/bootx64.efi
+    '';
+  };
+in
+{
+  system.activationScripts.hybrid-graphics = {
+    text = ''
+      if [[ -e /boot/efi/EFI/BOOT/bootx64_original.efi ]]; then
+        # We interpret this as apple-set-os-loader being already installed
+        exit 0
+      elif [[ -e /boot/efi/EFI/BOOT/BOOTX64.EFI ]] then
+        mv /boot/efi/EFI/BOOT/BOOTX64.EFI  /boot/efi/EFI/BOOT/bootx64_original.efi
+        cp ${apple-set-os-loader-installer}/bootx64.efi /boot/efi/EFI/BOOT/bootx64.efi
+      else
+        echo "Error: /boot/efi/EFI/BOOT/BOOTX64.EFI is missing"
+      fi
+    '';
+  };
+  environment.etc."modprobe.d/apple-gmux.conf".text = ''
+    # Enable the iGPU by default if present
+    options apple-gmux force_igd=y
+  '';
+  environment.systemPackages = with pkgs; [ apple-set-os-loader-installer ];
+}