Re: [Qemu-devel] [PATCH v5 10/11] dataplane: add virtio-blk data plane code

[Stefan Hajnoczi]

On Thu, Dec 06, 2012 at 01:33:58PM +0200, Michael S. Tsirkin wrote:
> On Wed, Dec 05, 2012 at 09:47:09PM +0100, Stefan Hajnoczi wrote:
> > virtio-blk-data-plane is a subset implementation of virtio-blk.
> 
> I already asked this:
> 
> what confuses me a bit is how, being a subset, it exposes the
> same feature bits. For example wce config is ineffective, right?
> So I think it should not expose WCE feature bit.

It works like vhost - the virtio negotiation and setup is still handled
by QEMU but the actual vring processing is done by dataplane.

virtio-blk-data-plane works with cache=none.  You're right that WCE
should not be toggled because we don't automatically flush after every
request.

Stefan