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

[Jason Wang <jasowang@redhat.com>]

On Tue, Jun 6, 2023 at 7:56âPM Michael S. Tsirkin <mst@redhat.com> wrote:
>
> On Mon, Jun 05, 2023 at 10:12:59PM +0000, Parav Pandit wrote:
> > Rolling v4 now.
>
> Great thanks! I think the result will be in a good shape from
> the ABI point of view. Good job!
>
> I think so far Jason was the only one with significant comments
> on the series so let's see what he says.

I can't say I like this. I prefer to do meditation on top of a modern
device with some lightweight features like _F_LEAGCY_HEADER. I don't
see any advantages of a new legacy ABI over _F_LEGACY_HEADER. I don't
want to repeat but I don't get any response here

https://lore.kernel.org/virtio-dev/CACGkMEuixsBibSq_pEQvcKOH0WBQWnta4Q2c28SV8qTS8gaVcA@mail.gmail.com/#t

>
> From my personal POV what will be left to do to get this
> feature ready for merging would be
>
> - tightening the language:
> - thinking of and addressing all kind of corner cases.

We need first to check whether it's possible (not too late) to find
all the corner cases.

Thanks

>
>
> Since by now from our email discussions I have I think
> a decent understanding of how the feature is supposed to work
> I understand how these things work but I think there are still
> things that would be a bit unclear for an unprepared reader.
>
> Just to give a random example, there's no explicit
> time where the member kind of switches to the legacy/back to modern
> mode. I am guessing setting DRIVER bit through legacy interface
> does this. We'll want to list that.
>
> I'll try to help find these issues and maybe even suggest wording.
>
> I've delayed commenting on these until the high level design is agreed
> on, didn't want to make you waste time on polishing as the patches
> undergo significant changes, and I suggest you do the same in v4: let's
> make sure there's a wide agreement on the ABI then focus on the spec
> language.
>
>
>
> --
> MST
>