See: https://bugzilla.redhat.com/show_bug.cgi?id=1003610 Libvirt should expose xen blktap support in capabilities XML so virt-manager can stop looking at /proc/modules. Also, a xen user reported that with recent xen, driver_name=tap2 works but driver_name=tap doesn't: http://www.redhat.com/archives/virt-tools-list/2013-June/msg00031.html Might be worth investigating as well
Just dropped explicit blktap support entirely since it's deprecated upstream: commit 7c10d8a27f0f635c185d1b85d6d26120d51c8aa2 Author: Cole Robinson <crobinso> Date: Wed Sep 23 17:26:48 2015 -0400 devicedisk: Tweak driver defaults for xen Following some discussion here: https://bugzilla.redhat.com/show_bug.cgi?id=1171550 jfehlig suggested better defaults for modern xen. End result is: - Drop the blktap check, since it's deprecated (yaay) - If xen + block device, use driver_name=phy - Otherwise if on modern enough libvirt + libxl, do the same thing we do for qemu.