flake.nix

# commands:
# n build .#nixosConfigurations.legacy390_64.config.system.build.toplevel
# n build .#nixosConfigurations.legacy390_32.config.system.build.toplevel

{
  description = "test building nvidia legacy 390 drivers with Linux 5.10";

  outputs = { self, nixpkgs }: {

    nixosConfigurations =
      let generic = system: nixpkgs.lib.nixosSystem {
        inherit system;
        modules = [
          ({ config, pkgs, ... }: {
            # setup
            nixpkgs.config.allowUnfree = true;
            boot.loader.grub.devices = [ "/dev/nodev" ];
            fileSystems."/" = { device = "/dev/nodev"; };

            # pick kernel
            boot.kernelPackages = pkgs.linuxPackages_5_10;

            # pick nvidia packages
            services.xserver.videoDrivers = [ "nvidia" ];
            services.xserver.enable = true;
            hardware.nvidia.package = config.boot.kernelPackages.nvidiaPackages.legacy_390;
            hardware.nvidia.nvidiaPersistenced = true;
          })
        ];
      };
      in
      {
        legacy390_64 = generic "x86_64-linux";
        legacy390_32 = generic "i686-linux";
      };
  };
}