Peter Krempa <pkre...@redhat.com> writes: > On 03/01/13 21:04, Anthony Liguori wrote: >> Eric Blake <ebl...@redhat.com> writes: >> >>> Stefan Berger and I discovered on IRC that virtio-rng is unable to >>> support fd passing. We attempted: >>> >>> qemu-system-x86_64 ... -add-fd set=4,fd=34,opaque=RDONLY:/dev/urandom >>> -object rng-random,id=rng0,filename=/dev/fdset/4 -device >>> virtio-rng-pci,rng=rng0,bus=pci.0,addr=0x6 >> >> Why are you using th rng-random backend instead of the rng-egd backend? > > There are two issues with using the egd backend for unprepared devices: > > 1) The backend spits out "\x20\x40" commands(egd blocking entropy > request for 0x40 bytes) so it really has to be used with some kind of > EGD server implementation otherwise it might feed your /dev/random with > predictable bytes if used directly.
Yes. That's the point. > > 2) performance of the egd backend is terrible as I've reported here > https://bugzilla.redhat.com/show_bug.cgi?id=915381 (yes I'm aware that I > probably should have filed a upstream bug too, but I was hoping Amit > would do it in the process) > > On my machine I managed to do 0.2KiB/s with the egd backend both with > using constant data as a high performance source, but also with a true > random number generator (in the Raspberry pi SoC, sources 107KiB/s of > entropy). The rng-random backend performs a bit better averaging > 1.2MiB/s. That's a bug that I wasn't aware of until you wrote this. I'll look into it next week. Regards, Anthony Liguori > > Peter
