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

[Parav Pandit <parav@nvidia.com>]

> 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.