Re: [virtio-comment] Re: [virtio-dev] Re: [virtio-comment] Re: [PATCH v5] virtio-net: device does not deliver partially checksummed packet and may validate the checksum

[Heng Qi <hengqi@linux.alibaba.com>]

å 2023/12/21 äå9:34, Jason Wang åé:
> On Wed, Dec 20, 2023 at 3:35âPM Michael S. Tsirkin <mst@redhat.com> wrote:
> > On Wed, Dec 20, 2023 at 02:30:01PM +0800, Heng Qi wrote:
> > > But why are we discussing this?
> > I think basically at this point everyone is confused about what
> > the feature does. right now we have packets
> > with
> > #define VIRTIO_NET_HDR_F_NEEDS_CSUM     1       -> partial
> > #define VIRTIO_NET_HDR_F_DATA_VALID     2       -> unnecessary
> > and packets without either                      -> none
> >
> > if both 1 and 2 are set then linux uses VIRTIO_NET_HDR_F_NEEDS_CSUM but
> > I am not sure it's not a mistake. Maybe it does not matter.
> >
> > What does this new thing do? So far all we have is "XDP will turn it on"
> > which is not really sufficient. I assumed it somehow replaces
> > partial with complete.
> It looks not? CHECKSUM_COMPLETE is less optimal than
> CHECKSUM_UNNCESSARY as validation is still needed.
>
> If I understand correctly, this new thing wants DATA_VALID only.

Disable NEEDS_CSUM or calculate fully checksummed packets to fully 
checksummed packets (how this is done does not matter).
The driver will only receive two types of packets: CHECKSUM_NONE and 
DATA_VALID (CHECKSUM_UNNECESSARY).

Thanksï

> Thanks
>
>
>
> > That would make sense for many reasons,
> > for example the checksum fields in the header can be reused
> > for other purposes. But maybe not?
> >
> >
> > --
> > MST