[libvirt] RFC: virtio-rng and /dev/urandom

Libvirt currently rejects using host /dev/urandom as an input source for a virtio-rng device. The only accepted sources are /dev/random and /dev/hwrng. This is the result of discussions on qemu-devel around when the feature was first added (2013). Examples: http://lists.gnu.org/archive/html/qemu-devel/2012-09/msg02387.html https://lists.gnu.org/archive/html/qemu-devel/2013-03/threads.html#00023 libvirt's rejection of /dev/urandom has generated some complaints from users: https://bugzilla.redhat.com/show_bug.cgi?id=1074464 * cited: http://www.2uo.de/myths-about-urandom/ http://www.redhat.com/archives/libvir-list/2016-March/msg01062.html http://www.redhat.com/archives/libvir-list/2016-April/msg00186.html I think it's worth having another discussion about this, at least with a recent argument in one place so we can put it to bed. I'm CCing a bunch of people. I think the questions are: 1) is the original recommendation to never use virtio-rng+/dev/urandom correct? 2) regardless of #1, should we continue to reject that config in libvirt? Thanks, Cole