Re: [Qemu-devel] [PATCH] virtio: Make memory barriers be memory barriers

[Avi Kivity]

On 09/06/2011 09:55 AM, Paolo Bonzini wrote:
> On 09/06/2011 05:12 AM, David Gibson wrote:
> > I'm not "fixing ppc".  I'm fixing a fundamental flaw in the protocol
> > implementation._So far_  I've only observed the effects on ppc, but
> > that doesn't mean they don't exist.
>
> Actually Michael is right.  The implementation is correct on x86, 
> though wrong anywhere else (perhaps s390?).  On those architectures 
> you do not need rmb() and wmb().

Are we sure?  Nothing prevents the guest from using weakly-ordered 
writes, is there?  For example, using MOVNTDQ.

Although in that case the guest is probably required to issue an SFENCE.

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error compiling committee.c: too many arguments to function