Passthrough mode only works as expected when running as root. On
Debian/Ubuntu systems qemu runs as user 'libvirt-qemu' and group 'kvm'
so all shared files must be chowned to grant access from guests.
Symlinks created on the host are still problematic because the Plan 9
filesystem has no direct notion of symbolic links, see [1].
[1] - http://ericvh.github.com/9p-rfc/rfc9p2000.u.html
Guest and network configuration is setup using the libvirt
virtualization API. The [start|stop]_testing scripts have been updated
accordingly.
qemu/KVM does not currently support a hostfs, so the shared build tree
mount has been dropped for now.