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Date: Wed, 30 Jul 2014 17:25:00 +0200
From: Paolo Bonzini <pbonzini@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH 14/15] hw/block/virtio-blk: create
 num_queues vqs if dataplane is enabled
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To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Kevin Wolf <kwolf@redhat.com>, Peter Maydell <peter.maydell@linaro.org>, Fam Zheng <famz@redhat.com>, Ming Lei <ming.lei@canonical.com>, qemu-devel@nongnu.org, Stefan Hajnoczi <stefanha@redhat.com>

Il 30/07/2014 17:12, Michael S. Tsirkin ha scritto:
>> > 
>> > Dataplane must not be a change to the guest ABI.  If you implement this
>> > feature you have to implement it for both dataplane and non-dataplne.
>> > 
>> > Paolo
> Actually, I think different backends at runtime should be allowed to
> change guest visible ABI.  For example if you give qemu a read only
> backend this is guest visible right?

Dataplane is not meant to be a different backend, it's just moving stuff
out to a separate thread.  It's only due to QEMU limitation that it
doesn't share the vring code (and these patches include a lot of steps
backwards where dataplane becomes != non-dataplane).

Paolo