lttng-modules: new package

Add linux kernel modules needed to do kernel tracing with LTTng.

To make them available to lttng in NixOS, add this to configuration.nix:

  boot.extraModulePackages = [ pkgs.linuxPackages.lttngModules ];

pkgs/os-specific/linux/lttng-modules/default.nix

@@ -0,0 +1,31 @@
+{ stdenv, fetchurl, kernelDev }:
+
+stdenv.mkDerivation rec {
+  pname = "lttng-modules-2.2.1";
+  name = "${pname}-${kernelDev.version}";
+
+  src = fetchurl {
+    url = "https://lttng.org/files/lttng-modules/${pname}.tar.bz2";
+    sha256 = "00ww1443ssv614s1ix6zby8llaf6zzlxcf5k4w7jsyji47ng33m2";
+  };
+
+  patches = [ ./lttng-fix-build-error-on-linux-3.2.patch ];
+
+  preConfigure = ''
+    export KERNELDIR="${kernelDev}/lib/modules/${kernelDev.modDirVersion}/build"
+    export INSTALL_MOD_PATH="$out"
+  '';
+
+  installPhase = ''
+    make modules_install
+  '';
+
+  meta = with stdenv.lib; {
+    description = "Linux kernel modules for LTTng tracing";
+    homepage = http://lttng.org/;
+    license = with licenses; [ lgpl21 gpl2 mit ];
+    platforms = platforms.linux;
+    maintainers = [ maintainers.bjornfor ];
+  };
+
+}