From: Stephen Hemminger <shemminger@vyatta•com>
To: "Yan, Zheng" <zheng.z.yan@intel•com>
Cc: Martin Volf <martin.volf.42@gmail•com>,
"shemminger@linux-foundation•org"
<shemminger@linux-foundation•org>,
"bridge@lists•linux-foundation.org"
<bridge@lists•linux-foundation.org>,
"netdev@vger•kernel.org" <netdev@vger•kernel.org>,
"davem@davemloft•net" <davem@davemloft•net>,
"wcang@sfc•wide.ad.jp" <wcang@sfc•wide.ad.jp>
Subject: Re: sky2 hw csum failure
Date: Tue, 15 Nov 2011 09:45:16 -0800 [thread overview]
Message-ID: <20111115094516.3eb54a1a@nehalam.linuxnetplumber.net> (raw)
In-Reply-To: <4EC23EE7.2010606@intel.com>
On Tue, 15 Nov 2011 18:28:55 +0800
"Yan, Zheng" <zheng.z.yan@intel•com> wrote:
> I re-tested the checksum code, both CHECKSUM_NONE and CHECKSUM_COMPLETE
> cases are OK. Maybe the bug is related to sky2.
>
> Regards
> Yan, Zheng
There are three types of receive checksumming:
1. Hardware does not do checksumming (CHECKSUM_NONE)
2. Hardware validates checksum (CHECKSUM_UNNECESSARY)
3. Hardware computes sum of bytes in skb (CHECKSUM_COMPLETE)
Most hardware does #2, but sky2 uses #3.
For the second case, the hardware does not look at headers but only
reports the one's complement value in ip_summed. It is up to the
protocol layers to adjust accordingly. This means if data is removed
or added the checksum needs to be adjusted.
next prev parent reply other threads:[~2011-11-15 17:45 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-11-15 9:05 sky2 hw csum failure Martin Volf
2011-11-15 10:28 ` Yan, Zheng
2011-11-15 17:45 ` Stephen Hemminger [this message]
2011-11-15 18:09 ` [RFT] bridge: checksum not updated after pull Stephen Hemminger
2011-11-15 19:51 ` Martin Volf
2011-11-16 22:47 ` David Miller
-- strict thread matches above, loose matches on Subject: below --
2011-11-28 12:10 sky2: hw csum failure Vincent Blut
2011-11-28 16:50 ` Stephen Hemminger
2011-11-28 19:20 ` Vincent Blut
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