Fedora xen - Mar 2007 - - kernel-xen, kernel-xen0 and kernel-xenU

Hi,

I''m using Xen on a Fedora Core 5, with kernel-xen0 on host and
kernel-xenU on guests.

Friday last I''ve installed kernel-xen both in host and guests, and
guests stopped to work. Now, I''m reinstalling kernel-xen0 on host and
kernel-xenU on guest...

I know kernel-xen0 is built to run on the Xen host, and kernel-xenU to
run on guests. But I can''t understand kernel-xen... when use it?

Thanks,

Davidson Paulo