anchor.diff:          '';
         };
   
  +      useGlamor = mkOption {
  +        type = types.bool;
  +        default = false;
  +        description = ''
  +          Whether to use the Glamor module for 2D acceleration,
  +          if possible.
  +        '';
  +      };
       };
   
     };
  
positive.code:           '')}
          EndSection
  
          # For each supported driver, add a "Device" and "Screen"
          # section.
          ${flip concatMapStrings drivers (driver: ''
  
negative.code:     nvidiaLegacy304 = { modules = [ kernelPackages.nvidia_x11_legacy304 ]; driverName = "nvidia"; };
      unichrome    = { modules = [ pkgs.xorgVideoUnichrome ]; };
      virtualbox   = { modules = [ kernelPackages.virtualboxGuestAdditions ]; driverName = "vboxvideo"; };
      ati = { modules = [ pkgs.xorg.xf86videoati pkgs.xorg.glamoregl ]; };
    };
  
    driverNames = config.hardware.opengl.videoDrivers;
  