RE: [virtio-dev] Re: [PATCH v6 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: 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.