[virtio-dev] Re: [virtio-comment] Re: [virtio-dev] [PATCH 08/11] transport-pci: Introduce virtio extended capability

Michael S. Tsirkin
2023-04-11T14:10:20Z

On Tue, Apr 11, 2023 at 02:07:27PM +0000, Parav Pandit wrote:
>
>
> > From: virtio-comment@lists.oasis-open.org <virtio-comment@lists.oasis-
> > open.org> On Behalf Of Michael S. Tsirkin
>
> > > >
> > > > now, imagine someone building a new device. if existing drivers are
> > > > not a concern, it is possible to move capabilities all to extended
> > > > space. is that possible while keeping the bios working?
> > > >
> > > unlikely as bios is looking in the legacy section.
> >
> > what do you mean by the legacy section?
> >
> Existing virtio PCI capabilities which are in the PCI capabilities region in first 256 bytes of the PCI config space.

well, of course, my question was for a new, future device, can
we put all capabilities in the extended space? will
we be able to teach bios to access these?

> > > New capabilities like legacy (and pasid) has no backward compat
> > > requirement from bios and drivers.
> > > so they can start from new.
> >
> > sure.