switch to two boot modes: with or without dgpu

modules/nixos/nvidia.nix

@@ -6,38 +6,31 @@
 }:
 {
 
+  # Allow to use the nvidia driver in the special case
+  # Use in the boot menu
+  specialisation = {
+    nvidia-enabled = {
+      configuration = {
+        system.nixos.tags = [ "nvidia-enabled" ];
         # Enable OpenGL
         hardware.graphics = {
           enable = true;
         };
-
-  # Load nvidia driver for Xorg and Wayland
-  services.xserver.videoDrivers = ["nvidia"];
-
-  # specify nvidia driver version
         hardware.nvidia = {
+          prime = {
+            sync.enable = true;
+            # reverseSync.enable = true;
+            # allowExternalGpu = false;
+            nvidiaBusId = "PCI:1:0:0";
+            intelBusId = "PCI:0:2:0";
 
-    # Modesetting is required.
+          };
           modesetting.enable = true;
-
-    # Nvidia power management. Experimental, and can cause sleep/suspend to fail.
-    # Enable this if you have graphical corruption issues or application crashes after waking
-    # up from sleep. This fixes it by saving the entire VRAM memory to /tmp/ instead 
-    # of just the bare essentials.
           powerManagement.enable = false;
-
-    # Fine-grained power management. Turns off GPU when not in use.
-    # Experimental and only works on modern Nvidia GPUs (Turing or newer).
           powerManagement.finegrained = false;
-
-    # the open source drivers are not compatible with the old 1050ti
           open = false;
+          nvidiaSettings = false;
 
-    # Enable the Nvidia settings menu,
-	  # accessible via `nvidia-settings`.
-    nvidiaSettings = true;
-
-    # Optionally, you may need to select the appropriate driver version for your specific GPU.
           package = config.boot.kernelPackages.nvidiaPackages.mkDriver {
             version = "565.77"; # latest
             sha256_64bit = "sha256-CnqnQsRrzzTXZpgkAtF7PbH9s7wbiTRNcM0SPByzFHw=";
@@ -46,14 +39,34 @@
             settingsSha256 = "sha256-VUetj3LlOSz/LB+DDfMCN34uA4bNTTpjDrb6C6Iwukk=";
             persistencedSha256 = "sha256-wnDjC099D8d9NJSp9D0CbsL+vfHXyJFYYgU3CwcqKww=";
           };
+        };
 
-    prime = {
+        boot.extraModprobeConfig = "";
-      offload = {
+        boot.blacklistedKernelModules = [];
-        enable = true;
+        services.udev.extraRules = "";
-        enableOffloadCmd = true;
+        services.xserver.videoDrivers = ["nvidia"];
-      };
-      intelBusId = "PCI:0:2:0";
-      nvidiaBusId = "PCI:1:0:0";
       };
     };
+  };
+
+
+  # In the global configuration, we blacklist the nouveau driver and load the nvidia driver
+  boot.extraModprobeConfig = lib.mkDefault ''
+    blacklist nouveau
+    options nouveau modeset=0
+  '';
+  
+  services.udev.extraRules = lib.mkDefault ''
+    # Remove NVIDIA USB xHCI Host Controller devices, if present
+    ACTION=="add", SUBSYSTEM=="pci", ATTR{vendor}=="0x10de", ATTR{class}=="0x0c0330", ATTR{power/control}="auto", ATTR{remove}="1"
+    # Remove NVIDIA USB Type-C UCSI devices, if present
+    ACTION=="add", SUBSYSTEM=="pci", ATTR{vendor}=="0x10de", ATTR{class}=="0x0c8000", ATTR{power/control}="auto", ATTR{remove}="1"
+    # Remove NVIDIA Audio devices, if present
+    ACTION=="add", SUBSYSTEM=="pci", ATTR{vendor}=="0x10de", ATTR{class}=="0x040300", ATTR{power/control}="auto", ATTR{remove}="1"
+    # Remove NVIDIA VGA/3D controller devices
+    ACTION=="add", SUBSYSTEM=="pci", ATTR{vendor}=="0x10de", ATTR{class}=="0x030000", ATTR{power/control}="auto", ATTR{remove}="1"
+  '';
+
+  boot.blacklistedKernelModules = lib.mkDefault [ "nouveau" "nvidia" "nvidia_drm" "nvidia_modeset" ];  
+
 }