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Date: Fri, 01 Mar 2013 21:41:29 +0100
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Subject: Re: [Qemu-devel] virtio-rng and fd passing
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To: Stefan Berger <stefanb@linux.vnet.ibm.com>
Cc: "qemu-devel@nongnu.org" <qemu-devel@nongnu.org>, "H. Peter Anvin" <hpa@zytor.com>

Il 01/03/2013 21:13, Stefan Berger ha scritto:
> On 03/01/2013 02:37 PM, H. Peter Anvin wrote:
>> On 02/28/2013 04:36 PM, Eric Blake wrote:
>>> 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
>>>
>> Unrelated, but you really, really, really don't want to pass
>> /dev/urandom there, use /dev/random.
> 
> From what I am reading about /dev/random is that it will start blocking
> once not enough entropy is available anymore.

Yes, and the purpose of virtio-rng is not to provide fancy random
numbers.  It's to provide actual entropy.

Paolo