From: Eric Dumazet <eric.dumazet@gmail.com>
To: Cong Wang <xiyou.wangcong@gmail.com>
Cc: Linux Kernel Network Developers <netdev@vger.kernel.org>,
Saeed Mahameed <saeedm@mellanox.com>,
Eric Dumazet <edumazet@google.com>
Subject: Re: [Patch net] mlx5: fixup checksum for ethernet padding
Date: Tue, 27 Nov 2018 17:25:51 -0800 [thread overview]
Message-ID: <0e6a8a08-b181-b17a-1330-0159808e9a42@gmail.com> (raw)
In-Reply-To: <CAM_iQpW2=rTa-QZxK5ygvr=UgM9Lcxr_NyPiD=1jh3Hgovn2gQ@mail.gmail.com>
On 11/27/2018 04:07 PM, Cong Wang wrote:
> On Tue, Nov 27, 2018 at 3:48 PM Eric Dumazet <eric.dumazet@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.
next prev parent reply other threads:[~2018-11-28 12:25 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-27 23:21 [Patch net] mlx5: fixup checksum for ethernet padding Cong Wang
2018-11-27 23:23 ` Cong Wang
2018-11-27 23:48 ` Eric Dumazet
2018-11-28 0:07 ` Cong Wang
2018-11-28 1:11 ` Saeed Mahameed
2018-11-28 1:38 ` Cong Wang
2018-11-28 1:25 ` Eric Dumazet [this message]
2018-11-28 1:42 ` Cong Wang
2018-11-28 1:48 ` Eric Dumazet
2018-11-28 1:52 ` Cong Wang
2018-11-29 21:51 ` kbuild test robot
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