anchor.diff:  
         substituteInPlace tools/python/xen/xend/XendQCoWStorageRepo.py \
           --replace /usr/sbin/qcow-create $out/sbin/qcow-create
  +
  +      # Xen's stubdoms need various sources that it usually fetches at
  +      # build time using wget.  We can't have that.
  +      ${flip concatMapStrings stubdomSrcs (x: let src = fetchurl x; in ''
  +        cp ${src} stubdom/${src.name}
  +      '')}
       '';
   
     installPhase =
  
positive.code:   meta = {
      homepage = http://www.xen.org/;
      description = "Xen hypervisor and management tools for Dom0";
    };
  }
  
negative.code: 
    buildInputs =
      [ which zlib pkgconfig SDL openssl python libuuid gettext ncurses
        dev86 iasl pciutils bzip2 xz texinfo
      ];
  
    makeFlags = "PREFIX=$(out) CONFIG_DIR=/etc";
  
    buildFlags = "xen tools stubdom";
  
    preBuild =
      ''
  