[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

["Michael S. Tsirkin" <mst@redhat.com>]

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. 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


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