anchor.diff:  
     src = fetchgit {
       url = git://git.ipxe.org/ipxe.git;
  -    sha256 = "11w8b0vln3skfn8r1cvzngslz12njdkwmnacyq3qffb96k2dn2ww";
  +    sha256 = "12ijrq451fj2x3i7c7xjlxig5mwbhmgzqjvmfl2sza953vfbk4vw";
       inherit rev;
     };
   
  
positive.code: { stdenv, fetchgit, perl, cdrkit, syslinux, xz, openssl }:
  
  let
    date = "20160831";
    rev = "827dd1bfee67daa683935ce65316f7e0f057fe1c";
  in
  
  stdenv.mkDerivation {
  
negative.code:   installPhase = ''
      mkdir -p $out
      cp bin/ipxe.dsk bin/ipxe.usb bin/ipxe.iso bin/ipxe.lkrn bin/undionly.kpxe $out
  
      # Some PXE constellations especially with dnsmasq are looking for the file with .0 ending
      # let's provide it as a symlink to be compatible in this case.
      ln -s undionly.kpxe $out/undionly.kpxe.0
    '';
  
    meta = with stdenv.lib;
  