Nvidia dgpu prime offload mode + amd igpu + wayland?

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I got this working:

  • For the CPU, newest kernel is desirable (6.14)
  • The “latest” nvidia driver in nixpkgs is not latest, you need to go to nixos-unstable for it, but you can’t selectively pick a kernel module from unstable while using the stable kernel, so I use mkDriver to install 570 directly (see in config below). In the future when newer drivers are stable you should be able to just use package = config.boot.kernelPackages.nvidiaPackages.stable;
  • You can’t use sway as your compositor. That was my main problem. I assumed the compositors wouldn’t have HW compat issues since that’s not how things usually work on X11. Under gnome, everything works fine.
    • Edit: Turns out you can use sway without disabling nvidia, as long as you tell sway to specifically use the amd card, see next post
  • To run a steam game with the nvidia card with this setup you just change your launch options to nvidia-offload %command%
  • For reasons I don’t understand gamescope only works with amd though. You can set DRI_PRIME=1 to force amd, which you may expect should be unnecessary since the point of this offload mode is to require an opt-in, but vulkan apps can choose to use whichever card they want anyway, so you may need it. For example the test app vkcube requires this.

nvidia.nix (import into configuration.nix):

{ config, lib, pkgs, ... }:

{
  boot.kernelPackages = pkgs.linuxPackages_6_14;

  # Enable OpenGL
  hardware.graphics = {
    enable = true;
    enable32Bit = true;
  };

  # Load nvidia driver for Xorg and Wayland
  services.xserver.videoDrivers = ["nvidia"];

  hardware.nvidia = {

    # 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;

    # Use the NVidia open source kernel module (not to be confused with the
    # independent third-party "nouveau" open source driver).
    # Support is limited to the Turing and later architectures. Full list of
    # supported GPUs is at:
    # https://github.com/NVIDIA/open-gpu-kernel-modules#compatible-gpus
    # Only available from driver 515.43.04+
    open = true;

    # 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.latest;

    package = config.boot.kernelPackages.nvidiaPackages.mkDriver {
      version = "570.133.07";
      # this is the third one it will complain is wrong
      sha256_64bit = "sha256-LUPmTFgb5e9VTemIixqpADfvbUX1QoTT2dztwI3E3CY=";
      # unused
      sha256_aarch64 = "sha256-2l8N83Spj0MccA8+8R1uqiXBS0Ag4JrLPjrU3TaXHnM=";
      # this is the second one it will complain is wrong
      openSha256 = "sha256-9l8N83Spj0MccA8+8R1uqiXBS0Ag4JrLPjrU3TaXHnM=";
      # this is the first one it will complain is wrong
      settingsSha256 = "sha256-XMk+FvTlGpMquM8aE8kgYK2PIEszUZD2+Zmj2OpYrzU=";
      # unused
      persistencedSha256 = "sha256-4l8N83Spj0MccA8+8R1uqiXBS0Ag4JrLPjrU3TaXHnM=";
    };

    prime = {
      offload = {
        enable = true;
        enableOffloadCmd = true;
      };
      # Make sure to use the correct Bus ID values for your system!
      amdgpuBusId = "PCI:197:0:0"; # For AMD GPU
      nvidiaBusId = "PCI:196:0:0";
    };
  };
}