Comment 1 for bug 668429

It seems something more is needed in order to get it to work properly. Performing the following results in initramfs saying this when attempting to mount the root file system:

mount error: cifs filesystem not supported by the system
mount error(19): No such device
Refer to the mount.cifs(8) manual page (e.g. man mount.cifs)
nfsmount: need a server
nfsmount: need a server
nfsmount: need a server
...

To get mount.cifs into the initrd, first you must have install mount.cifs

To do this run:
# sudo apt-get install smbfs

Found some instructions here:
https://help.ubuntu.com/community/LiveCDCustomization

# mkdir lztempdir
# cd lztempdir
# lzma -dc -S .lz ../initrd.lz | cpio -imvd --no-absolute-filenames

Then do:

# cp `which mount.cifs` sbin/mount.cifs

Then pack it back up:

# find . | cpio --quiet --dereference -o -H newc | lzma -7 > ../initrd.cifs.lz