[virtio-dev] RE: [virtio-comment] Re: [PATCH 09/11] transport-pci: Describe PCI MMR dev config registers

Parav Pandit
2023-04-16T13:42:02Z

> From: virtio-comment@lists.oasis-open.org <virtio-comment@lists.oasis-
> open.org> On Behalf Of Michael S. Tsirkin
> Sent: Friday, April 14, 2023 2:57 AM

> Do you refer to the trick Jason proposed where BAR0 is memory but otherwise
> matches legacy BAR0 exactly? Is this your preferred solution at this point then?

We look at it again.
Above solution can work reliably only for a very small number of PF and that too with very special hardware circuitry due to the reset flow.

Therefore, for virtualization below interface is preferred.
a. For transitional device legacy configuration register transport over AQ,
Notification to utilize transitional device notification area of the BAR.

b. Non legacy interface of transitional and non-transitional PCI device to access direct PCI device without mediation.