Re: [PATCH 1/2] rngd: add udev rule to source from hwrng if virtio-rng present

On 08/11/2014 06:30 AM, Torsten Duwe wrote:

On Mon, Aug 11, 2014 at 12:45:27PM +0530, Amit Shah wrote:

quoted

What's the suggested value for rng->quality, though, for virtio-rng
that I can use to ensure the kthread starts?

Should I use the 700 (70%) as proposed in the original patchset?  I'm
not exactly sure how that value will be used as well..

There is no such thing as a suggested value, every number is wrong
to some degree.  The quality is an estimation of how random your
source really is; it's a property of your hardware. If the device is
virtual you're in trouble ;-)

Either you have a way to query the underlying real hardware, or
you do your whitening and entropy estimation in the backend driver --
then you can claim 100%.

virtio-rng I feel we could rank at 100%; it is supposed to feed
/dev/random-quality randomness from the VMM.  If the VMM is hostile you
have already lost anyway.

	-hpa