Re: [virtio-dev] Re: [PATCH v6 4/4] transport-pci: Introduce group legacy group member config region access

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

On Mon, Jun 19, 2023 at 05:35:04PM +0000, Parav Pandit wrote:
> 
> 
> > From: Michael S. Tsirkin <mst@redhat.com>
> > Sent: Monday, June 19, 2023 1:26 PM
> 
> > > > Also these devices will use non-transitional ID but they in fact do
> > > > have a legacy interface so using this definition they are
> > > > transitional devices. Maybe we need to add when we describe the
> > > > device ID text like "non transitional devices and transitional devices utilizing
> > commands XYZ" ...?
> > >
> > > Transitional device has specific meaning, I am not sure we should muddy it.
> > 
> > 
> > 
> > To simplify transition from these earlier draft interfaces, a device MAY
> > implement:
> > 
> > \begin{description}
> > \item[Transitional Device]
> >         a device supporting both drivers conforming to this
> >         specification, and allowing legacy drivers.
> > \end{description}
> > 
> > 
> > I agree it can be read this way. The issue is a lot of text in the spec just assumes
> > that "has legacy interface == transitional device".
> > 
> > 
> > 
> > For example:
> > When using the legacy interface the driver MAY access the device-specific
> > configuration region using any width accesses, and a transitional device MUST
> > present driver with the same results as when accessed using the ``natural''
> > access method (i.e.
> > 32-bit accesses for 32-bit fields, etc).
> > 
> > 
> > If we break the assumption we need to audit the spec for this
> > assumption and again, I really would rather not.
> 
> We are not breaking the assumption. Above listed requirement is already captured in the legacy interface conformance section.
> So I am not sure what extra to write here.
>  

Hmm not sure what's unclear.  I can try to explain the issue again.

These devices have a legacy interface yes?
So they should be transitional to avoid breaking assumption.


But they are not *exactly*
in that they don't have a transitional device ID.

At least the device id section needs extra text
then to explain this?

Or do you just want to make them have transitional ID?


-- 
MST