I have attempted to start X in a rawhide LXC guest on a Fedora 16 host, using echo a > /sys/fs/cgroup/devices/libvirt/lxc/Rawhide/devices.allow to allow me to create all the necessary devices in /dev in the guest (dangerous, I know, but I only ran that command after the guest systemd finished booting). This is with the nouveau open source driver. I ran X using /usr/bin/startx -- :7 vt7 Immediately the host X server dies, even though it's on a different virtual terminal (VT1). It seems to be something to do with DRM. The /var/log/Xorg.0.log in the host says something about drmSetMaster failing. What's strange is that according to the guest Xorg.7.log, DRM opening fails there too: "drmOpenDevice: open result is -1, (No such device)". If there is no such device (even though I created it), how can the guest be affecting the host? I think it might possibly be related to https://bugzilla.redhat.com/show_bug.cgi?id=680677 Maybe the guest X immediately fails to start but for some reason does not release the DRM master (at all, or quickly enough), and the host X tries to regain the DRM master but fails and dies. I looked at some other drivers to see if any other X drivers have better handling of the latter condition, but I couldn't find any which do a retry in this case. I would report a bug, but I'm not sure which Fedora component to report this against.