{
  description = "My visionfive 2 setup";

  #inputs.nixpkgs.url = "github:NickCao/nixpkgs/riscv"; # https://github.com/NickCao/nixpkgs/tree/riscv
  #inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixos-23.11";
  inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
  inputs.nixos-hardware.url = "github:nixos/nixos-hardware";

  #inputs.nickcao-rv64.url = "github:NickCao/nixos-riscv"; # https://github.com/NickCao/nixos-riscv
  #inputs.nickcao-rv64.inputs.nixpkgs.follows = "nixpkgs";
  #inputs.zhao-rv64.url = "github:zhaofengli/nixos-riscv64"; # https://github.com/zhaofengli/nixos-riscv64

  outputs = {
    self,
    nixpkgs,
    nixos-hardware,
    ...} @ inputs:
  let
    forSystems = systems: f: nixpkgs.lib.genAttrs systems (system: f rec {
      inherit system;
      pkgs = nixpkgs.legacyPackages.${system};
      lib  = nixpkgs.legacyPackages.${system}.lib;
    });
    #forAllSystems = forSystems nixpkgs.lib.systems.flakeExposed;
    forAllSystems = forSystems [
      "x86_64-linux"
      "aarch64-linux"
      "riscv64-linux"
    ];
  in {
    inherit inputs;

    nixosModules = rec {
      # helper, ensures cross
      rv64-maybe-cross = { config, lib, ... }: lib.mkIf (config.nixpkgs.system != "riscv64-linux") {
        # (system != "riscv64-linux") => do cross
        nixpkgs.crossSystem.config = "riscv64-unknown-linux-gnu";
        nixpkgs.crossSystem.system = "riscv64-linux";
      };

      # hardware, pick one
      vf2-r12a = { lib, ...}: {
        imports = [ rv64-maybe-cross ];
        hardware.deviceTree.name = "starfive/jh7110-starfive-visionfive-2-v1.2a.dtb";
      };
      vf2-r12a-8gb = {
        imports = [ vf2-r12a ];
        hardware.deviceTree.overlays = [{
          name = "8GB-patch";
          dtsFile = "${nixos-hardware}/starfive/visionfive/v2/8gb-patch.dts";
        }];
      };
      vf2-r13b = { lib, ...}: {
        imports = [ rv64-maybe-cross ];
        hardware.deviceTree.name = "starfive/jh7110-starfive-visionfive-2-v1.3b.dtb"; # default
      };
      vf2-r13b-8gb = {
        imports = [ vf2-r13b ];
        hardware.deviceTree.overlays = [{
          name = "8GB-patch";
          dtsFile = "${nixos-hardware}/starfive/visionfive/v2/8gb-patch.dts";
        }];
      };

      # install method, pick one
      vf2-qemu = { lib, ...}: {
        imports = [ "${nixos-hardware}/starfive/visionfive/v2" ./qemu-vm.nix ];
      };
      vf2-sd-installer = {
        imports = [ "${nixos-hardware}/starfive/visionfive/v2/sd-image-installer.nix" ];
        sdImage.compressImage = false;
      };
      vf2-sd-image = {
        imports = [ "${nixos-hardware}/starfive/visionfive/v2/sd-image.nix" ];
        sdImage.compressImage = false;
      };
      vf2-nvme = { pkgs, ... }: let
        firmware = pkgs.callPackage "${inputs.nixos-hardware}/starfive/visionfive/v2/firmware.nix" { };
      in {
        imports = [ "${nixos-hardware}/starfive/visionfive/v2" ];
        fileSystems."/".device = "/dev/disk/by-label/NIXOS_ROOT";
        fileSystems."/".fsType = "ext4";
        fileSystems."/boot/spl".device = "/dev/disk/by-label/UBOOT_SPL";
        fileSystems."/boot/spl".fsType = "vfat";
        fileSystems."/boot/spl".options = [ "nofail" "noauto" ]; # not critical
        fileSystems."/boot/firmware".device = "/dev/disk/by-label/UBOOT_FIRMWARE";
        fileSystems."/boot/firmware".fsType = "vfat";
        fileSystems."/boot/firmware".options = [ "nofail" "noauto" ]; # not critical
        boot.initrd.kernelModules = [ "nvme" ];
        #boot.loader.systemd-boot.enable = true;
        #boot.loader.efi.efiSysMountPoint = "/boot";
        #boot.loader.efi.canTouchEfiVariables = true;
        environment.systemPackages = [
          pkgs.efibootmgr
          pkgs.efivar
          firmware.updater-flash
          (pkgs.writeShellApplication {
            name = "visionfive2-firmware-update-ssd";
            runtimeInputs = [ pkgs.mtdutils ];
            text = ''
              flashcp -v ${firmware.spl}/share/starfive-visionfive2/spl.bin /dev/nvme0n1p1
              flashcp -v ${firmware.uboot-fit-image}/share/starfive-visionfive2/visionfive2_fw_payload.img /dev/nvme0n1p2
            '';
          })
        ];
      };
      vf2-nvme-image = {
        _module.args = { inherit inputs; };
        imports = [ vf2-nvme ./efi-image.nix ];
      };

      # components
      dhcp = {
        networking.interfaces.end0.useDHCP = true;
        networking.interfaces.end1.useDHCP = true;
      };
      minimal = { lib, ...}: let inherit (lib) mkDefault mkForce; in {
        #boot.enableContainers = mkDefault false;
        documentation.enable = mkDefault false;
        documentation.doc.enable = mkDefault false;
        documentation.info.enable = mkDefault false;
        documentation.man.enable = mkDefault false;
        documentation.nixos.enable = mkDefault false;
        #environment.noXlibs = mkDefault true;
        networking.firewall.enable = mkDefault false;
        programs.command-not-found.enable = false;
        security.audit.enable = mkDefault false;
        security.polkit.enable = mkForce false;
        services.logrotate.enable = mkDefault false;
        services.udisks2.enable = mkDefault false;
        #xdg.autostart.enable = mkDefault false;
        #xdg.icons.enable = mkDefault false;
        #xdg.mime.enable = mkDefault false;
        #xdg.sounds.enable = mkDefault false;
      };

      # hosts
      demo = { pkgs, ... }: {
        imports = [ minimal dhcp "${nixpkgs}/nixos/modules/profiles/base.nix" ];
        networking.hostName = "demo";
        environment.systemPackages = with pkgs;[ neofetch htop fd ripgrep ];
        system.stateVersion = "23.11";
      };
      asgaut = { pkgs, ... }: {
        imports = [ minimal dhcp ];
        networking.hostName = "asgaut";
        networking.domain =   "pbsds.net";
        networking.search = [ "pbsds.net" ];
        console.keyMap = "no";
        services.xserver.layout = "no";
        services.xserver.xkbVariant = "";
        time.timeZone = "Europe/Oslo";
        i18n.defaultLocale = "en_US.utf8";
        i18n.extraLocaleSettings.LC_TIME = "nb_NO.utf8";
        environment.systemPackages = with pkgs;[ neofetch htop fd ripgrep ];
        system.stateVersion = "23.11";
      };
    };

    packages = forAllSystems ({ system, ... }: let
      m = self.nixosModules;
      mkNixos = modules: nixpkgs.lib.nixosSystem { inherit system modules; };
      mkAll = hostname: modules: with m; {
        "${hostname}-sd-installer" = (mkNixos (modules ++ [ vf2-sd-installer ])).config.system.build.sdImage;
        "${hostname}-sd-image"     = (mkNixos (modules ++ [ vf2-sd-image     ])).config.system.build.sdImage;
        "${hostname}-nvme-image"   = (mkNixos (modules ++ [ vf2-nvme-image   ])).config.system.build.efiImage;
        "${hostname}-qemu"         = (mkNixos (modules ++ [ vf2-qemu         ])).config.system.build.vm;
      };
      in (mkAll "demo-r12a"     [ m.demo   m.vf2-r12a     ])
      // (mkAll "demo-r12a-8gb" [ m.demo   m.vf2-r12a-8gb ])
      // (mkAll "demo-r13b"     [ m.demo   m.vf2-r13b     ])
      // (mkAll "demo-r13b-8gb" [ m.demo   m.vf2-r13b-8gb ])
      // (mkAll "asgaut"        [ m.asgaut m.vf2-r12a-8gb ])
      // {
        default = self.packages.${system}.demo-r12a-qemu;
      });

    nixosConfigurations = let
      m = self.nixosModules;
      mkSystem = modules: nixpkgs.lib.nixosSystem { system = "x86_64-linux"; inherit modules; };
    in {
      asgaut = mkSystem (with m; [ asgaut vf2-r12a-8gb vf2-nvme ]);
    };
  };
}