For folks who’ve not yet noticed, the long foreshadowed dropping of Xen from RHEL6 for anything other than as a guest OS is still on:
Red Hat Enterprise Linux 6 Beta is supported as a Xen guest for the x86 and x86_64 architectures. Additionally, Red Hat Enterprise Linux 6 Beta can be used as both a Xen paravirtualized (PV) guest or as a Fully virtualized (FV) guest with PV drivers. Due to paravirtualized operations (pv-ops) being included in the kernel, the same kernel can be used for either mode of operation as well as for bare metal. There is no support for using Red Hat Enterprise Linux 6 Beta as a Xen host.
If you are using Xen with RHEL as the base for your virtualisation you’ll be wanting to look for alternatives..