anchor.diff:          pkgs.xterm
         ]
         ++ optional (elem "nvidia" driverNames) kernelPackages.nvidia_x11
  -      ++ optional (elem "nvidiaLegacy" driverNames) kernelPackages.nvidia_x11_legacy
  +      ++ optional (elem "nvidiaLegacy96" driverNames) kernelPackages.nvidia_x11_legacy96
  +      ++ optional (elem "nvidiaLegacy173" driverNames) kernelPackages.nvidia_x11_legacy173
         ++ optional (elem "virtualbox" driverNames) xorg.xrefresh
         ++ optional (elem "ati_unfree" driverNames) kernelPackages.ati_drivers_x11;
         
  
positive.code:             XORG_DRI_DRIVER_PATH = "${pkgs.mesa}/lib/dri";
            } // optionalAttrs (elem "nvidia" driverNames) {
              LD_LIBRARY_PATH = "${xorg.libX11}/lib:${xorg.libXext}/lib:${kernelPackages.nvidia_x11}/lib";
            } // optionalAttrs (elem "nvidiaLegacy" driverNames) {
              LD_LIBRARY_PATH = "${xorg.libX11}/lib:${xorg.libXext}/lib:${kernelPackages.nvidia_x11_legacy}/lib";
            } // optionalAttrs (elem "ati_unfree" driverNames) {
              LD_LIBRARY_PATH = "${xorg.libX11}/lib:${xorg.libXext}/lib:${kernelPackages.ati_drivers_x11}/lib:${kernelPackages.ati_drivers_x11}/X11R6/lib64/modules/linux";
              XORG_DRI_DRIVER_PATH = "${kernelPackages.ati_drivers_x11}/lib/dri"; # is ignored because ati drivers ship their own unpatched libglx.so !
  
negative.code:     intel        = { modules = [ xorg.xf86videointel ]; };
      nv           = { modules = [ xorg.xf86videonv ]; };
      nvidia       = { modules = [ kernelPackages.nvidia_x11 ]; };
      nvidiaLegacy96 = { modules = [ kernelPackages.nvidia_x11_legacy96 ]; driverName = "nvidia"; };
      nvidiaLegacy173 = { modules = [ kernelPackages.nvidia_x11_legacy173 ]; driverName = "nvidia"; };
      openchrome   = { modules = [ xorg.xf86videoopenchrome ]; };
      sis          = { modules = [ xorg.xf86videosis ]; };
      unichrome    = { modules = [ pkgs.xorgVideoUnichrome ]; };
  