# Pastebin V3k23wIo
{ lib, pkgs, config, ... }: {
  systemd.targets.my-kexec = {
    requires = ["my-systemd-kexec.service"];
    after = ["my-systemd-kexec.service"];
    unitConfig = {
      DefaultDependencies = "no";
      AllowIsolate = "yes";
    };
  };

  systemd.services.my-prepare-kexec = {
    before = ["my-systemd-kexec.service"];
    wantedBy = ["my-kexec.target"];
    unitConfig.DefaultDependencies = false;
    serviceConfig.Type = "oneshot";
    path = [pkgs.kexectools];
    script = ''
      # Don't load the current system profile if we already have a kernel loaded
      if [[ 1 = "$(</sys/kernel/kexec_loaded)" ]] ; then
        echo "kexec kernel has already been loaded, prepare-kexec skipped"
        exit 0
      fi

      p=$(readlink -f /nix/var/nix/profiles/system)
      if ! [[ -d $p ]]; then
        echo "Could not find system profile for prepare-kexec"
        exit 1
      fi
      echo "Loading NixOS system via kexec."
      initrd=$(mktemp -p /run initrd.XXXXXXXXXX)
      cat $p/initrd /path/to/secretInitrd > $initrd
      exec kexec --load $p/kernel --initrd=$initrd --append="$(cat $p/kernel-params) init=$p/init"
    '';
  };

  systemd.services.my-systemd-kexec = {
    requires = ["shutdown.target" "umount.target" "final.target"];
    after = ["shutdown.target" "umount.target" "final.target"];
    unitConfig.DefaultDependencies = "no";
    serviceConfig.Type = "oneshot";
    script = ''
      echo Rebooting via kexec.
      exec ${pkgs.kexectools}/bin/kexec -e
    '';
  };
}