Re: [RFC 7/11] virtio_pci: new, capability-aware driver.

["Michael S. Tsirkin" <mst@xxxxxxxxxx>]

On Wed, Dec 21, 2011 at 11:03:25AM +1030, Rusty Russell wrote:
> > > What does the host do
> > > if the guest screws things up?  How long do you wait for them to
> > > complete the seqlock?  Or does it save the old version for use in the
> > > duration?
> > 
> > Yes, it will have to only apply the change when seqlock is dropped.
> 
> If the seqlock is in normal memory, how does it get notified?  It would
> have to poll.  That's annoying, since you don't know when to give up and
> declare the device terminally broken.

OK, so you think all devices need a config vq then?
It actually has other benefits:
- devices don't need a design choice between configuration and vq
- minimum number of MSI vectors per device will be 1, not 2
- reduced PCI memory usage
- configuration updates become more lightweight

-- 
MST
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