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Subject: [Qemu-devel] Re: [PATCH 0/2] fix virtio_blk serial pci config
	breakage
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To: Anthony Liguori <anthony@codemonkey.ws>
Cc: john cooper <john.cooper@third-harmonic.com>, "Michael S. Tsirkin" <mst@redhat.com>, john cooper <john.cooper@redhat.com>, Rusty Russell <rusty@rustcorp.com.au>, qemu-devel@nongnu.org, Vadim Rozenfeld <vrozenfe@redhat.com>, jens.axboe@oracle.com

On 09/29/2009 03:51 PM, Anthony Liguori wrote:
>> The change this patch implements is passing of the
>> identify data through a mapping established by
>> PCI BAR #5 rather than the PCI config area, the
>> latter of which resulted in the above breakage.
>
>
> This is a massive layering violation.  The virtio-blk ABI cannot make 
> demands of the transport.

True.

>
> The better solution would be to move the entire virtio-pci config 
> space to a separate BAR that's an MMIO region.  Then there is no 
> practical limit on the size of the config area.

Don't some fast-paths accesses go through the config space?  Using mmio 
will slow them down.

-- 
error compiling committee.c: too many arguments to function