will return success when the kernel is built without support of
the capability mode.
It is important to note, that I'm taking a more conservative approach
with these changes and it will be done in small steps.
Reviewed by: jhb
MFC after: 6 weeks
Differential Revision: https://reviews.freebsd.org/D18744
Original virtqueue design allows queued and out-of-order processing, but
helpers added in r253440 suppose only direct blocking in-order one.
It could be fine for network, etc., but it is a huge limitation for storage
devices.
Call through to /dev/random synchronously to fill
virtio buffers with RNG data.
Tested with FreeBSD-CURRENT and Ubuntu guests.
Submitted by: Leon Dang
Discussed with: markm
MFC after: 3 weeks
Sponsored by: Nahanni Systems