* LVM support (in stage 2; having / on LVM is not yet supported). LVM

triggers a new-devices event so that the filesystems job mounts file
  systems on the logical volumes.

svn path=/nixos/trunk/; revision=7478

configuration/system.nix

@@ -152,6 +152,7 @@ rec {
     pkgs.gzip
     pkgs.iputils
     pkgs.less
+    pkgs.lvm2
     pkgs.module_init_tools
     pkgs.nano
     pkgs.netcat

configuration/upstart.nix

@@ -26,6 +26,11 @@ import ../upstart-jobs/gather.nix {
       inherit (pkgs) writeText cleanSource udev procps;
     })
       
+    # Makes LVM logical volumes available. 
+    (import ../upstart-jobs/lvm.nix {
+      inherit (pkgs) kernel module_init_tools lvm2;
+    })
+      
     # Hardware scan; loads modules for PCI devices.
     (import ../upstart-jobs/hardware-scan.nix {
       inherit (pkgs) kernel module_init_tools;

upstart-jobs/lvm.nix

@@ -0,0 +1,30 @@
+{kernel, module_init_tools, lvm2}:
+
+{
+  name = "lvm";
+  
+  job = "
+start on udev
+#start on new-devices
+
+script
+
+    # Load the device mapper.
+    export MODULE_DIR=${kernel}/lib/modules/
+    ${module_init_tools}/sbin/modprobe dm_mod || true
+
+    # Scan for block devices that might contain LVM physical volumes
+    # and volume groups.
+    #${lvm2}/sbin/vgscan
+
+    # Make all logical volumes on all volume groups available, i.e.,
+    # make them appear in /dev.
+    ${lvm2}/sbin/vgchange --available y
+
+    initctl emit new-devices
+    
+end script
+
+  ";
+
+}