RE: [PATCH v11 3/4] virtio-net: define UDP tunnel segmentation offload feature

Parav Pandit
2025-01-20T08:57:36Z

> From: Paolo Abeni <pabeni@redhat.com>
> Sent: Monday, January 20, 2025 2:15 PM
> To: Parav Pandit <parav@nvidia.com>; virtio-comment@lists.linux.dev
> Cc: maxime.coquelin@redhat.com; Eelco Chaudron <echaudro@redhat.com>;
> Jason Wang <jasowang@redhat.com>; Stefano Garzarella
> <sgarzare@redhat.com>; Willem de Bruijn <willemb@google.com>;
> kshankar@marvell.com
> Subject: Re: [PATCH v11 3/4] virtio-net: define UDP tunnel segmentation
> offload feature
>
> On 1/19/25 9:06 AM, Parav Pandit wrote:
> > Hi Paolo, Michael,
> >
> >> From: Paolo Abeni <pabeni@redhat.com>
> >> Sent: Wednesday, November 27, 2024 3:07 PM
> >>
> >>
> >> +\item[VIRTIO_NET_F_GUEST_UDP_TUNNEL_GSO (46)] Driver can receive
> >> GSO
> >> +packets
> >> + carried by a UDP tunnel.
> >> +
> >> +\item[VIRTIO_NET_F_HOST_UDP_TUNNEL_GSO (48)] Device can receive
> >> GSO
> >> +packets
> >> + carried by a UDP tunnel.
> >
> > Feature bits 42 to 49 are not applicable to device specific type. They are
> reserved.
> > Please see the note.
> >
> > Current spec description is:
> >
> > 0 to 23, and 50 to 127 Feature bits for the specific device type
> > 24 to 41 Feature bits reserved for extensions to the queue and feature
> > negotiation mechanisms, see 6
> > 42 to 49, and 128 and above Feature bits reserved for future extensions.
>
> Thank you for the head-up! I missed the above point.
>
> > So 2 bits of these patch and of patch 4, 46 to 49 to be shifted to bits 65 to
> 68.
>
> I can cook and send a new version of the series with the above change, but it
> will take a few days as I can't start working on it before Thursday and I
> want/intend to update and test the PoC code accordingly.
>
Please do not send now as the voting has started.
We will be able to handle under a separate patch+vote in as fixup soon.
This will avoid voting related rework.

I would like to have Miachel's feedback if there was any past history for reserving bits 42-49, or it was just flexibility..