[virtio-dev] 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>]

在 2023/12/21 上午9:34, Jason Wang 写道:
> On Wed, Dec 20, 2023 at 3:35 PM 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).

Thanks！

>
> 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
>>


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