netdev - Re: e1000 tcp checksum incorrect, x86 64b

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Date:	Fri, 28 Sep 2007 12:08:16 +0800
From:	Herbert Xu <herbert@...dor.apana.org.au>
To:	jonsmirl@...il.com (Jon Smirl)
Cc:	netdev@...r.kernel.org
Subject: Re: e1000 tcp checksum incorrect, x86 64b

Jon Smirl <jonsmirl@...il.com> wrote:
>
> App is writing seven bytes to the socket. Socket write timeout expires
> and the seven bytes are sent. The checksum is not getting inserted
> into the packet. It is set to a constant 0x8389 instead of the right
> value.  App is gmpc 0.15.4.95, Revision: 6794
> 
> Attached Wireshark packet trace show the problem. e1000 is 192.168.1.4
> 64bit, Q6600. Dell Dimension 9200

Wireshark is broken.  It needs to know TP_STATUS_CSUMNOTREADY
means that the checksum is partial and will only be completed
when the hardware sends the packet out.

Alternatively disable checksum offload with ethtool.

Cheers,
-- 
Visit Openswan at http://www.openswan.org/
Email: Herbert Xu ~{PmV>HI~} <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
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