On 11/27/2018 04:07 PM, Cong Wang wrote:
> On Tue, Nov 27, 2018 at 3:48 PM Eric Dumazet <eric.duma...@gmail.com> wrote:
>>
>> But the padding might be added on normal packets (say 1000 bytes + 3 bytes
>> of padding) ?
>
> I never see other padding cases than ETH_ZLEN. Does ethernet standard
> require padding for other cases? I only read the section "3.2.8 Pad field" in
> the standard.
>
Padding can be done by senders, eg using AF_PACKET,
added at the tail of a regular IP/IP6 frame of 1000 or 6000 bytes.
Note that mlx5 will presumably set CHECKSUM_UNNECESSARY for standard protocols,
so if you want to reproduce the issue, you might need to find an IP frame that
mlx5 is not able to checksum validate.
Maybe a non-first fragment will do the trick.
