The xenblk, xennet drivers are missing from the rawhide xen initrd so installation under xen is impossible.
The xen kernel needs to provide all of the same things as the main kernel. In this case, modules.block and modules.networking so that anaconda can determine the modules to pull out of the kernel.
Fix committed to CVS, tag kernel-xen-2_6-2_6_21-2935_fc8. Scratch build sent to Koji: http://koji.fedoraproject.org/koji/taskinfo?taskID=150217
Fix updated on CVS, tag kernel-xen-2_6-2_6_21-2936_fc8. Scratch build finished: http://koji.fedoraproject.org/koji/taskinfo?taskID=150379
The module lists included in the new package look correct. I have submitted a non-scratch build: http://koji.fedoraproject.org/koji/taskinfo?taskID=150548 Should it be included on F8 Test2?
Current rawhide works fine now so I assume that test2 will be OK as well.