Hi all, It may be my setup but this is what I found. Current yum update. Only breaks xen boots.Most recent yum upgrade to 3.8.1-201 omits the initramfs line in its grub2.cfg file.
After adding these lines it boots. echo 'Loading initial ramdisk ...' module /initramfs-3.8.1-201.fc18.x86_64.img -- xen mailing list xen@xxxxxxxxxxxxxxxxxxxxxxx https://admin.fedoraproject.org/mailman/listinfo/xen