Enable klogd on Linux < 3.5

On Linux >= 3.5, systemd takes care of logging kernel messages.

modules/module-list.nix

@@ -77,7 +77,7 @@
   ./services/hardware/udev.nix
   ./services/hardware/udisks.nix
   ./services/hardware/upower.nix
-  #./services/logging/klogd.nix
+  ./services/logging/klogd.nix
   ./services/logging/logcheck.nix
   ./services/logging/logrotate.nix
   ./services/logging/logstash.nix

modules/services/logging/klogd.nix

@@ -1,19 +1,42 @@
 { config, pkgs, ... }:
 
-###### implementation
+with pkgs.lib;
 
 {
+  ###### interface
 
-  jobs.klogd =
-    { description = "Kernel log daemon";
+  options = {
 
-      startOn = "started syslogd";
-
-      path = [ pkgs.sysklogd ];
-
-      exec =
-        "klogd -c 1 -2 -n " +
-        "-k $(dirname $(readlink -f /run/booted-system/kernel))/System.map";
+    services.klogd.enable = mkOption {
+      type = types.bool;
+      default = versionOlder (getVersion config.boot.kernelPackages.kernel) "3.5";
+      description = ''
+        Whether to enable klogd, the kernel log message processing
+        daemon.  Since systemd handles logging of kernel messages on
+        Linux 3.5 and later, this is only useful if you're running an
+        older kernel.
+      '';
     };
 
+  };
+
+
+  ###### implementation
+
+  config = mkIf config.services.klogd.enable {
+
+    jobs.klogd =
+      { description = "Kernel Log Daemon";
+
+        wantedBy = [ "multi-user.target" ];
+
+        path = [ pkgs.sysklogd ];
+
+        exec =
+          "klogd -c 1 -2 -n " +
+          "-k $(dirname $(readlink -f /run/booted-system/kernel))/System.map";
+      };
+
+  };
+
 }