If you are running Rawhide or F16 you should be about to get the
xen-4.1.1-6 packages when you next update (if you haven't got them
already). These contain partial systemd support (for the xenstored startup
script) to solve some shutdown problems I was seeing. Also your grub2
configuration should now be updated when you install, upgarde or remove
the xen-hypervisor package.
The conversion to systemd from traditional startup scripts isn't exact,
and although I think it does the right thing there may be problems, so let
me know if you see any issues.
Another problem that I am aware of is that if you use libvirt to access
xen may get blocked by selinux, so you may need to run in permissive mode
if you want to do this successfully.
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