{ lib, config, options, ... }:
{
  options = {
    clan.virtualisation = {
      cores = lib.mkOption {
        type = lib.types.ints.positive;
        default = 1;
        description = lib.mdDoc ''
          Specify the number of cores the guest is permitted to use.
          The number can be higher than the available cores on the
          host system.
        '';
      };

      memorySize = lib.mkOption {
        type = lib.types.ints.positive;
        default = 1024;
        description = lib.mdDoc ''
          The memory size in megabytes of the virtual machine.
        '';
      };

      graphics = lib.mkOption {
        type = lib.types.bool;
        default = true;
        description = lib.mdDoc ''
          Whether to run QEMU with a graphics window, or in nographic mode.
          Serial console will be enabled on both settings, but this will
          change the preferred console.
        '';
      };
    };
  };

  config = {
    system.clan.vm.config = {
      inherit (config.clan.virtualisation) cores graphics;
      memory_size = config.clan.virtualisation.memorySize;
    };

    virtualisation = lib.optionalAttrs (options.virtualisation ? cores) {
      memorySize = lib.mkDefault config.clan.virtualisation.memorySize;
      graphics = lib.mkDefault config.clan.virtualisation.graphics;
      cores = lib.mkDefault config.clan.virtualisation.cores;
    };
  };
}