[virtio-dev] Re: [PATCH v10 4/4] transport-pci: Introduce group legacy group member config region access

["Michael S. Tsirkin" <mst@redhat.com>]

On Thu, Jul 06, 2023 at 06:53:55PM +0000, Parav Pandit wrote:
> 
> 
> > From: Michael S. Tsirkin <mst@redhat.com>
> > Sent: Thursday, July 6, 2023 2:48 PM
> 
> 
> > > The driver of the owner device can send a driver notification to the
> > > member device by executing
> > VIRTIO_ADMIN_CMD_LEGACY_COMMON_CFG_WRITE
> > > with the \field{offset} matching \field{Queue Notify} and the
> > > \field{data} containing the virtqueue index to be notified or by
> > > performing memory or I/O write in
> > 
> > split to two sentences please. E.g.
> > Alternatively, the driver ...
> >
> Ack.
> Moving to it dedicated para, as in this first para the notification region and command is not yet introduced.
>  
> > > the any of the notification region at offset 0 supplied by the device
> > > in
> > 
> > the any is agrammatical
> > 
> > > VIRTIO_ADMIN_CMD_LEGACY_NOTIFY_INFO result.
> > >
> > > > Please also call out the unusual configuration where the type is
> > > > "member" and then you have the owner driver access the memory of the
> > member device.
> > > > People might be confused.
> > > >
> > > > I also think we should explain that order of entries is a hint to
> > > > driver: use the 1st entry that you can.
> > >
> > > Driver really can choose any valid entry out of the 4 that driver likes.
> > > I really don't see a need for overwriting this area as I fail to see why one will
> > expose multiple entries from the device side in reality.
> > 
> > I do: one for owner one for member.
> Yes, I am aware of choice or multi-entry. :)
> 
> > which is best for device is device specific.
> > 
> > I don't know what do you mean by "overwriting". Explaining in detail?
> :) being too verbose than needed.
> 
> > You feel like this because you spent a lot of time thinking about the area and
> > there is a specific solution is very clear in your head.
> > First readers are not like this and second they might have a different solution.
> 
> I am just saying to keep things simple. Let driver choose any entry it wants to use instead of device deciding on priority and hints etc.

Let's say driver can support both types which to choose? 
As the order is there anyway, why not just prescribe entries are
used in order?

-- 
MST


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