On Wed, 2015-09-02 at 17:48 +1000, David Gibson wrote: > On Wed, Sep 02, 2015 at 11:04:12AM +0530, Amit Shah wrote: > > On (Mon) 31 Aug 2015 [20:46:02], Thomas Huth wrote: > > > The PAPR interface provides a hypercall to pass high-quality > > > hardware generated random numbers to guests. So let's provide > > > this call in QEMU, too, so that guests that do not support > > > virtio-rnd yet can get good random numbers, too. > > > > virtio-rng, not rnd. > > > > Can you elaborate what you mean by 'guests that do not support > > virtio-rng yet'? The Linux kernel has had the virtio-rng driver since > > 2.6.26, so I'm assuming that's not the thing you're alluding to. > > > > Not saying this hypercall isn't a good idea, just asking why. I think > > there's are valid reasons like the driver fails to load, or the driver > > is compiled out, or simply is loaded too late in the boot cycle. > > Yeah, I think we'd be talking about guests that just don't have it > configured, although I suppose it's possible someone out there is > using something earlier than 2.6.26 as well. Note that H_RANDOM has > been supported under PowerVM for a long time, and PowerVM doesn't have > any virtio support. So it is plausible that there are guests out > there with with H_RANDOM support but no virtio-rng support, although I > don't know of any examples specifically. RHEL6 had virtio support, > including virtio-rng more or less by accident (since it was only > supported under PowerVM). SLES may not have made the same fortunate > error - I don't have a system handy to check.
There also could be folks who want to run non-Linux operating systems, which don't have a virtio-rng driver, crazy I know :) cheers
