anchor.diff:      services.acpid.enable = true;
   
       # Create /dev/nvidia-uvm when the nvidia-uvm module is loaded.
  -    services.udev.extraRules = optionalString nvidia-drivers_kernelspace.uvm ''
  +    services.udev.extraRules = ''
  +      KERNEL=="nvidia", RUN+="${pkgs.stdenv.shell} -c 'mknod -m 666 /dev/nvidiactl c $(grep nvidia-frontend /proc/devices | cut -d \  -f 1) 255'"
  +      KERNEL=="nvidia_modeset", RUN+="${pkgs.stdenv.shell} -c 'mknod -m 666 /dev/nvidia-modeset c $(grep nvidia-frontend /proc/devices | cut -d \  -f 1) 254'"
  +      KERNEL=="card*", SUBSYSTEM=="drm", DRIVERS=="nvidia", RUN+="${pkgs.stdenv.shell} -c 'mknod -m 666 /dev/nvidia%n c $(grep nvidia-frontend /proc/devices | cut -d \  -f 1) %n'"
         KERNEL=="nvidia_uvm", RUN+="${pkgs.stdenv.shell} -c 'mknod -m 666 /dev/nvidia-uvm c $(grep nvidia-uvm /proc/devices | cut -d \  -f 1) 0'"
       '';
   
  
positive.code:     services.xserver.screenSection = ''
        Option "RandRRotation" "on"
      '';
  
    };
  
  
negative.code:   inherit (lib)
      elem
      mkIf
      singleton;
  
    drivers = config.services.xserver.videoDrivers;
  