Currently you cannot use generic ethernet interfaces with qemu when sVirt is enabled. This is because libvirt was having qemu handle the TAP creation and it doesn't have the rights to do so. This patch changes it so that libvirt handles and TAP creation and deletion. Passing the TAP as a file descriptor to qemu instead. Backwards capability has been maintained in the following manner. If a script is defined for the interface in the domain XML then it uses the old method of having qemu create the TAP and running the ifup script. If a script is not defined then the new method is used. When used with a script(old method) you will still be unable to use sVirt. You can use the old method without running a script. To do this define script='no' this will use the old method, but without a script. I have been running this patched version for while now on Fedora 15. I haven't ran into any issues. Hopefully I didn't miss anything. Previous patch proposal https://www.redhat.com/archives/libvir-list/2011-July/msg00407.html Thanks, Tyler