Re: [virtio-dev] Re: [External] Re: [PATCH v3 3/4] content: Introduce driver/device auxiliary notifications for MMIO

[Stefan Hajnoczi <stefanha@redhat.com>]

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On Mon, Oct 31, 2022 at 02:22:22PM +0000, Usama Arif wrote:
> On 27/10/2022 22:27, Stefan Hajnoczi wrote:
> > On Fri, Oct 07, 2022 at 05:56:42PM +0100, Usama Arif wrote:
> > > This includes the additions to the corresponding device and driver
> > > conformances.
> > > 
> > > Signed-off-by: Usama Arif <usama.arif@bytedance.com>
> > > Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
> > 
> > You can keep this. One thought:
> > 
> > I realized that virtio-mmio support won't be very useful until
> > virtio-mmio gets MSI-X support because drivers currently cannot
> > differentiate between device auxiliary notifications.
> > 
> > Stefan
> 
> Did you mean drivers currently cannot differentiate between "driver"
> auxiliary notifications? The driver will be able to be able to choose the
> index it wants to notifiy using DeviceAuxNotificationIndex.

Yes, sorry!

> 
> I can add the following line in the Interrupt Status change of the patch if
> it makes sense?
> "As MSI-X is not available, it is not possible to determine which driver
> auxiliary notification occured, hence only a single notification is
> supported."

Yes, that is how I understood the mechanism to work. Depending on the
nature of the device-specific event, it may be unworkable for the driver
to have no way of identifying the exact event.

Stefan

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