Re: [virtio-dev] Re: [PATCH v3 0/3] transport-pci: Introduce legacy registers access using AQ

[Jason Wang <jasowang@redhat.com>]

On Fri, Jun 9, 2023 at 10:29âAM Parav Pandit <parav@nvidia.com> wrote:
>
>
> > From: Jason Wang <jasowang@redhat.com>
> > Sent: Thursday, June 8, 2023 10:07 PM
>
> > I think not since you fail to explain why this approach is better than simply
> > adding new features like _F_LEGACY_HEADER and _F_LEGACY_MAC.
>
> Please refer back to the requirements of cover letter and multiple past discussions.
> And Michael also explained...
>
> It is passthrough device, none of the 1.x objects are accessible or mediated by the hypervisor.

Let me quote my reply once again:

"
Hypervisor just need to prepare

1) legacy BAR with legacy config and device configuration space
2) modern BAR with modern capabilities (common cfg and device cfg)

For 2) it could be mapped directly to guest without any mediation For
1) hypervisor needs to mediate
"

There's zero mediation for 1.x objects at all. No?

For accessing 1.x objects by hypervisor, what's wrong with that
especially considering it is used for legacy mediation only but not
modern? (Btw, how do you define 1.x objects, isn't any facility via
adminq an 1.x object?)

In order to converge the discussion, maybe you can explain which one
of your 3 use cases and why can't work with _F_LEGACY_HEADER +
_F_LEGACY_MAC.

Thanks

>
> Cannot repeat more.