anchor.diff:  
   { config, pkgs, ... }:
   
  +with pkgs.lib;
  +
   let
  -
  -  inherit (pkgs.lib) mkOption types;
   
     options = {
   
  
positive.code:   # The initrd only has to mount / or any FS marked as necessary for
    # booting (such as the FS containing /nix/store, or an FS needed for
    # mounting /, like / on a loopback).
    fileSystems = pkgs.lib.filter
      (fs: fs.mountPoint == "/" || fs.neededForBoot)
      config.fileSystems;
  
  
negative.code:     kernel = modulesTree;
      allowMissing = true;
    };
  
  
    enableSplashScreen =
      config.boot.initrd.enableSplashScreen && kernelPackages.splashutils != null;
  
  
    # Some additional utilities needed in stage 1, like mount, lvm, fsck
  