From mboxrd@z Thu Jan  1 00:00:00 1970
From: Paolo Bonzini <pbonzini@redhat.com>
Date: Tue, 01 Oct 2013 09:58:11 +0000
Subject: Re: [PATCH 3/3] KVM: PPC: Book3S: Add support for hwrng found on some powernv systems
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References: <1380177066-3835-1-git-send-email-michael@ellerman.id.au> <1380177066-3835-3-git-send-email-michael@ellerman.id.au> <5243F933.7000907@redhat.com> <20131001083426.GB27484@concordia>
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To: Michael Ellerman <michael@ellerman.id.au>
Cc: linux-kernel@vger.kernel.org, Benjamin Herrenschmidt <benh@kernel.crashing.org>, Paul Mackerras <paulus@samba.org>, gleb@redhat.com, agraf@suse.de, mpm@selenic.com, herbert@gondor.hengli.com.au, linuxppc-dev@ozlabs.org, kvm@vger.kernel.org, kvm-ppc@vger.kernel.org, tytso@mit.edu

Il 01/10/2013 10:34, Michael Ellerman ha scritto:
>> If you really want to have the hypercall, implementing it in QEMU means
>> that you can support it on all systems, in fact even when running
>> without KVM.  
> 
> Sure, I can add a fallback to /dev/hwrng for full emulation.
> 
>> The QEMU command line would be something like "-object
>> rng-random,filename=/dev/random,id=rng0 -device spapr-rng,rng=rng0".
> 
> We can't use /dev/random like that. The PAPR specification, which is
> what we're implementing, implies that H_RANDOM provides data from a
> hardware source.

Then use /dev/hwrng.

I don't have POWER machines, but I still want to be able to test as much
as possible using emulation.

Paolo