Then package xen-source is outdated. The latest is 2.6.18. As the result more and more users needs to unmask the hard masked 2.6.21 (which is outdated as well) or to use third party ebuilds. Many new hardware will not work with the old 2.6.18 kernel. Please have a look at http://code.google.com/p/gentoo-xen-kernel/downloads/list where is a working (at least for me) xen-sources-2.6.27. Reproducible: Always
here is the state of the art kernel...needs xen unstable (3.4) http://git.kernel.org/?p=linux/kernel/git/jeremy/xen.git;a=shortlog;h=xen/dom0/hackery
*** This bug has been marked as a duplicate of bug 235911 ***