It looks like qemu/kvm at some point recently got a patch that neuters Nvidia driver's ability to tell it is running in a VM: http://www.eevblog.com/forum/chat/hacking-nvidia-cards-into-their-professional-counterparts/msg471413/#msg471413 It would sure be nice to be able to pinch the patches that do this and apply them in to Xen's QEMUs. Gordan