{ pkgs, ... }:

{
  boot.initrd.availableKernelModules = [
    "xhci_pci" "ahci" "sd_mod" "sdhci_pci"  # nixos-generate-config defaults
    "usb_storage"   # rpi needed this to boot from usb storage, i think.
    # "usbhid" "hid-generic"  # hopefully these will fix USB HID auto-sleep ?
  ];
  boot.initrd.kernelModules = [ ];
  boot.initrd.supportedFilesystems = [ "ext4" "btrfs" "ext2" "ext3" "vfat" ];
  # find more of these with sensors-detect
  boot.kernelModules = [
    "coretemp"
    "kvm-intel"
    "kvm-amd"  # desktop
    "amdgpu"   # desktop
  ];
  boot.extraModulePackages = [ ];
  boot.kernelParams = [ "boot.shell_on_fail" ];
  boot.consoleLogLevel = 7;

  # Use the systemd-boot EFI boot loader.
  boot.loader.systemd-boot.enable = true;
  boot.loader.systemd-boot.configurationLimit = 40;  # keep this many generations
  boot.loader.efi.canTouchEfiVariables = true;

  # enable cross compilation
  boot.binfmt.emulatedSystems = [ "aarch64-linux" ];
  # nixpkgs.crossSystem.system = "aarch64-linux";

  powerManagement.cpuFreqGovernor = "powersave";
  hardware.enableRedistributableFirmware = true;
  hardware.cpu.amd.updateMicrocode = true;    # desktop
  hardware.cpu.intel.updateMicrocode = true;  # laptop
  services.fwupd.enable = true;
  # powertop will default to putting USB devices -- including HID -- to sleep after TWO SECONDS
  powerManagement.powertop.enable = false;

  hardware.opengl.extraPackages = [
    # laptop
    pkgs.intel-compute-runtime
    pkgs.intel-media-driver  # new
    pkgs.libvdpau-va-gl      # new
    pkgs.vaapiIntel
    # desktop
    pkgs.rocm-opencl-icd
    pkgs.rocm-opencl-runtime
  ];
  hardware.opengl.driSupport = true;
  # For 32 bit applications
  hardware.opengl.driSupport32Bit = true;

  # TODO colin: does this *do* anything?
  swapDevices = [ ];

  # services.snapper.configs = {
  #   root = {
  #     subvolume = "/";
  #     extraConfig = {
  #       ALLOW_USERS = "colin";
  #     };
  #   };
  # };
  # services.snapper.snapshotInterval = "daily";
}