[libvirt-users] Using NFS to read image file

Hello: When I start the guest with an image on NFS file system, the ubuntu doesn't boot, It's remain on inittrams. I've tried to redefine the guest without <apic> <pae> configuration as I see on a blog, and I've increased the parameters of the mount to rsize=32768 and wsize=32768, but it still doesn't work. Can anyone give any advice to get it? Thank you very much. Marcela