Now properly add nvidiabl.

pkgs/os-specific/linux/nvidiabl/default.nix

@@ -0,0 +1,25 @@
+{ stdenv, fetchurl, kernel }:
+
+stdenv.mkDerivation {
+  name = "nvidiabl-0.85-${kernel.version}";
+
+  src = fetchurl {
+    url = "https://github.com/guillaumezin/nvidiabl/archive/v0.85.tar.gz";
+    sha256 = "1c7ar39wc8jpqh67sw03lwnyp0m9l6dad469ybqrgcywdiwxspwj";
+  };
+
+  preConfigure = ''
+    sed -i 's|/sbin/depmod|#/sbin/depmod|' Makefile
+  '';
+
+  makeFlags = [
+    "KDIR=${kernel.dev}/lib/modules/${kernel.modDirVersion}/build"
+    "DESTDIR=$(out)"
+  ];
+
+  meta = {
+    description = "Linux driver for setting the backlight brightness on laptops using NVIDIA GPU";
+    homepage = https://github.com/guillaumezin/nvidiabl;
+    license = stdenv.lib.licenses.gpl2;
+  };
+}

pkgs/top-level/all-packages.nix

@@ -6880,6 +6880,8 @@ let
 
     broadcom_sta = callPackage ../os-specific/linux/broadcom-sta/default.nix { };
 
+    nvidiabl = callPackage ../os-specific/linux/nvidiabl { };
+
     nvidia_x11 = callPackage ../os-specific/linux/nvidia-x11 { };
 
     nvidia_x11_legacy173 = callPackage ../os-specific/linux/nvidia-x11/legacy173.nix { };