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.