{ pkgs, ... }:
let
  inherit (pkgs.pseudofile) dir symlink;
  "getty.service" = {
    file =
    let
      login = pkgs.writeScript "login" ''
        #!/bin/ash
        exec /bin/ash
      '';
    in
    ''
      [Unit]
      Description="Serial shell"

      [Service]
      ExecStart=${pkgs.util-linux}/bin/agetty --login-program ${login} ttyS0
    '';
    mode = "0644";
  };
  "default.target" = {
    file = ''
      [Unit]
      Description="target to boot"
      Wants=getty.service
      After=getty.service
      AllowIsolate=yes
    '';
  };
  "sysinit.target" = {
    file = ''
      [Unit]
      Description="sysinit.target"
    '';
  };
in
{
  config = {
    kernel.config = {
      CGROUPS = "y";
      DEVTMPFS = "y";
      INOTIFY_USER = "y";
      SIGNALFD = "y";
      TIMERFD = "y";
      EPOLL = "y";
      UNIX = "y";
      SYSFS = "y";
      PROC_FS = "y";
      FHANDLE = "y";
    };
    boot.commandLine = [
      "systemd.log_level=7"
      #"systemd.crash_shell=true"
    ];
    filesystem = dir {
      etc = dir {
        systemd = dir {
          system = dir {
            inherit "default.target" "getty.service" "sysinit.target";
          };
        };
      };
      bin = dir {
        init = symlink "${pkgs.systemd}/bin/init";
      };
    };
  };
}