{ config, pkgs, ... }:
{
  # srvos
  system.activationScripts.preActivation.text = ''
    if [[ -e /run/current-system ]]; then
      echo "--- diff to current-system"
      ${pkgs.nvd}/bin/nvd --nix-bin-dir=${config.nix.package}/bin diff /run/current-system "$systemConfig"
      echo "---"
    fi
  '';
}