anchor.diff:        "--enable-osmesa"
         "--enable-openvg" "--enable-gallium-egl" # not needed for EGL in Gallium, but OpenVG might be useful
         #"--enable-xvmc" # tests segfault with 9.1.{1,2,3}
  -      "--enable-vdpau"
         #"--enable-opencl" # ToDo: opencl seems to need libclc for clover
       ];
   
  
positive.code: 
    src =  fetchurl {
      url = "ftp://ftp.freedesktop.org/pub/mesa/${version}/MesaLib-${version}.tar.bz2";
      sha256 = "0gbacnnacv4x8q27s8my4qhf2xq8q4nyhbs9y9688win4csm12n7";
    };
  
    prePatch = "patchShebangs .";
  
negative.code: */
  
  let
    version = "9.2.3";
    # this is the default search path for DRI drivers (note: X server introduces an overriding env var)
    driverLink = "/run/opengl-driver" + stdenv.lib.optionalString stdenv.isi686 "-32";
  in
  