Add support for NFS root file system.

Patch by Rickard Nilsson.

svn path=/nixos/trunk/; revision=29855

modules/system/boot/stage-1-init.sh

@@ -221,8 +221,10 @@ mountFS() {
     # For CIFS mounts, retry a few times before giving up.
     local n=0
     while true; do
-        if mount -t "$fsType" -o "$options" "$device" /mnt-root$mountPoint; then
-            break
+        if [ "$fsType" = "nfs" ]; then
+          nfsmount "$device" "/mnt-root$mountPoint" && break
+        else
+          mount -t "$fsType" -o "$options" "$device" "/mnt-root$mountPoint" && break
         fi
         if [ "$fsType" != cifs -o "$n" -ge 10 ]; then fail; break; fi
         echo "retrying..."

modules/system/boot/stage-1.nix

@@ -169,6 +169,11 @@ let
         cp ${kernelPackages.splashutils}/${kernelPackages.splashutils.helperName} $out/bin/splash_helper
       ''}
 
+      # Copy nfsmount if there is any NFS mounts required for boot.
+      ${optionalString (filter (fs: fs.fsType == "nfs" && (fs.mountPoint == "/" || fs.neededForBoot)) fileSystems != []) ''
+        cp -v ${pkgs.klibc}/lib/klibc/bin.static/nfsmount $out/bin
+      ''}
+
       ${config.boot.initrd.extraUtilsCommands}
 
       # Run patchelf to make the programs refer to the copied libraries.