anchor.diff:  
       system.activationScripts.setup-opengl =
         ''
  -        ln -sfn ${cfg.package} /run/opengl-driver
  +        ln -sfn ${package} /run/opengl-driver
           ${if pkgs.stdenv.isi686 then ''
             ln -sfn opengl-driver /run/opengl-driver-32
           '' else if cfg.driSupport32Bit then ''
  -          ln -sfn ${cfg.package32} /run/opengl-driver-32
  +          ln -sfn ${package32} /run/opengl-driver-32
           '' else ''
             rm -f /run/opengl-driver-32
           ''}
  
positive.code: 
    videoDrivers = config.services.xserver.videoDrivers;
  
    makePackage = p: p.buildEnv {
      name = "mesa-drivers+txc-${p.mesa_drivers.version}";
      paths =
        [ p.mesa_drivers
          p.mesa_noglu # mainly for libGL
          (if cfg.s3tcSupport then p.libtxc_dxtn else p.libtxc_dxtn_s2tc)
        ];
    };
  
  in
  
negative.code:       internal = true;
        description = ''
          The package that provides the 32-bit OpenGL implementation on
          64-bit systems. Used when <option>driSupport32Bit</option> is
          set.
        '';
      };
  
      hardware.opengl.extraPackages = mkOption {
        type = types.listOf types.package;
        default = [];
        description = ''
          Additional packages to add to OpenGL drivers.
        '';
      };
  
      hardware.opengl.extraPackages32 = mkOption {
        type = types.listOf types.package;
        default = [];
        description = ''
          Additional packages to add to 32-bit OpenGL drivers on
          64-bit systems. Used when <option>driSupport32Bit</option> is
          set.
        '';
      };
  