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

apple/t2/README.md

@@ -1,4 +1,4 @@
-## NixOS on T2 Macs
+# NixOS on T2 Macs
 
 This is the `nixos-hardware` module of the [T2 Linux Project](https://t2linux.org).
 
@@ -7,3 +7,32 @@ Overall, most features (WiFi, bluetooth, audio, touchbar, ...) of Macs are suppo
 Following [this guide](https://wiki.t2linux.org/distributions/nixos/installation/) is the recommended way to install, as it incudes the extra things you have to do on a T2 Mac.
 
 You can consult the [wiki](https://wiki.t2linux.org/) for information specific to T2 Macs.
+
+## Unlocking Internal iGPU
+
+The `apple-set-os-loader-installer.nix` module serves as an installer for the [`apple-set-os-loader`](https://github.com/Redecorating/apple_set_os-loader). This tool is designed to unlock the internal integrated GPU (iGPU) on certain MacBooks. See https://wiki.t2linux.org/guides/hybrid-graphics/ for more details.
+
+### What it Does:
+
+Upon activation, this module performs the following:
+
+- Renames the existing `BOOTX64.EFI` file to `bootx64_original.efi`.
+- Installs the `apple-set-os-loader` hook in its place as `bootx64.efi`.
+- Before the system boots the hook unlocks the iGPU and subsequently calls the original `bootx64_original.efi`.
+
+### How to Implement:
+
+1. **Integrate the apple-set-os-loader installer** into your `configuration.nix`:
+```
+imports = [
+  ...
+  "${builtins.fetchGit { url = "https://github.com/NixOS/nixos-hardware.git"; }}/apple/t2/apple-set-os-loader-installer.nix"
+];
+```
+
+2. **Rebuild your system**:
+```
+sudo nixos-rebuild switch
+```
+
+> **Note**: Always ensure compatibility and make backups of your data before making any system changes.

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 ];
+}