anchor.diff:        description = ''
           On 64-bit systems, whether to support Direct Rendering for
           32-bit applications (such as Wine).  This is currently only
  -        supported for the <literal>nvidia</literal> and 
  +        supported for the <literal>nvidia</literal> and
           <literal>ati_unfree</literal> drivers, as well as
           <literal>Mesa</literal>.
         '';
  
positive.code:       message = "Option driSupport32Bit is only supported on 64-bit systems.";
      };
  
      system.activation.scripts.setup-opengl =
        ''
          find /run -maxdepth 1 -name opengl-driver\* -exec rm -rf {} \;
          ln -sfn ${package} ${package.driverSearchPath}
          ${optionalString cfg.driSupport32Bit ''
            ln -sfn ${package32} ${package.driverSearchPath}
          ''}
        '';
  
      environment.sessionVariables.LD_LIBRARY_PATH = [
        "${package.driverSearchPath}/lib"
  
negative.code:     hardware.opengl.package = mkDefault (makePackage pkgs);
      hardware.opengl.package32 = mkDefault (makePackage pkgs_32);
  
      boot.extraModulePackages =
        optional (elem "virtualbox" videoDrivers) kernelPackages.virtualboxGuestAdditions;
    };
  }
  