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

{
  imports = [ ];

  options.me = {
    _9pfs_nix_store.enable = lib.mkOption {
      type = lib.types.bool;
      default = false;
      example = true;
      description = "Whether we want to mount /nix/store over 9pfs (useful in virtual machines to share a directory from the host as a persistent nix store.";
    };

    _9pfs_nix_store.is_iso = lib.mkOption {
      type = lib.types.bool;
      default = false;
      example = true;
      description = "Whether this build is for an ISO. It changes how we mount the nix store.";
    };
  };

  config = lib.mkIf config.me._9pfs_nix_store.enable (
    lib.mkMerge [
      (lib.mkIf config.me._9pfs_nix_store.is_iso {
        # fileSystems = {
        #   "/nix/store" = lib.mkForce {
        #     fsType = "overlay";
        #     device = "overlay";
        #     options = [
        #       "lowerdir=/nix/.ro-store"
        #       "upperdir=/store"
        #       "workdir=/work"
        #     ];
        #     depends = [
        #       "/nix/.ro-store"
        #       "/store"
        #       "/work"
        #     ];
        #   };

        #   "/store" = lib.mkForce {
        #     fsType = "9p";
        #     device = "nixstore";
        #     options = [
        #       "trans=virtio"
        #       "version=9p2000.L"
        #       "x-systemd.requires=modprobe@9pnet_virtio.service"
        #       "msize=16384" # Maximum packet size. Increasing this should improve performance at the cost of increased memory usage.
        #       "cache=loose"
        #     ];
        #   };
        # };
      })
      (lib.mkIf (!config.me._9pfs_nix_store.is_iso) {
        fileSystems = {
          "/nix/store" = lib.mkForce {
            fsType = "9p";
            device = "nixstore";
            neededForBoot = true;
            options = [
              "trans=virtio"
              "version=9p2000.L"
              "x-systemd.requires=modprobe@9pnet_virtio.service"
              "msize=16384" # Maximum packet size. Increasing this should improve performance at the cost of increased memory usage.
              "cache=loose"
            ];
          };
        };
      })
    ]
  );
}