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Date: Fri, 01 Mar 2013 15:34:27 -0500
From: Stefan Berger <stefanb@linux.vnet.ibm.com>
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Subject: Re: [Qemu-devel] virtio-rng and fd passing
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To: Anthony Liguori <anthony@codemonkey.ws>
Cc: "qemu-devel@nongnu.org" <qemu-devel@nongnu.org>

On 03/01/2013 03:04 PM, Anthony Liguori wrote:
> Eric Blake <eblake@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?

I followed the example on the libvirt website trying out the XML for the 
rng device while adpating the libvirt code to use fd passing and 
generating the -add-fd command line parameters.

>
> You can pass chardevs to the egd backend.  It's really not a good idea
> to pass a fd via rng-rangom.

Fine, then we won't use fd passing for this device, whatever the reason 
may be.

    Stefan