[virtio-dev] Re: [PATCH 02/11] transport-pci: Move transitional device id to legacy section

Michael S. Tsirkin
2023-04-02T07:55:04Z

On Fri, Mar 31, 2023 at 09:24:21PM +0000, Parav Pandit wrote:
>
>
> > From: Michael S. Tsirkin <mst@redhat.com>
> > Sent: Friday, March 31, 2023 2:44 AM
> >
> > On Fri, Mar 31, 2023 at 01:58:25AM +0300, Parav Pandit wrote:
> > > Currently PCI device discovery details for the transitional device are
> > > documented in two different sections.
> > >
> > > For example, PCI device and vendor ID registers are documented in
> > > 'Device Requirements: PCI Device Discovery' section, while PCI
> > > revision id is documented in 'Legacy Interfaces: A Note on PCI Device
> > > Discovery' section.
> > >
> > > Transitional devices requirements should be documented in "legacy
> > > interfaces" section as clearly mentioned in 'Legacy Interface: A Note
> > > on Feature Bits'.
> >
> > I already commented on this, I disagree.
> > Modern drivers must be able
> > to completely ignore legacy interface sections, but they do bind to transitional
> > device IDs.
> > This change breaks this assumption.
> >
> Legacy interface section holds the detail about transitional devices.
> We do not have,
> "Legacy only" section.
>
> It doesn't make sense to partial information in legacy and partial in other place.
> Modern drivers are not mentioned in the spec terminology section.
>
> Can you please explain, how can modern driver ignore the text " Transitional devices MUST have a PCI Revision ID of 0." written in legacy interface section?

Modern drivers ignore revision ID. It is 0 to accomodate legacy drivers.

--
MST