soekris/sis tx checksum problems

Bjoern A. Zeeb bzeeb-lists at
Wed Jun 20 10:10:14 UTC 2007

On Tue, 19 Jun 2007, David Cornejo wrote:


> I am using CURRENT on a Soekris 4801 (sis ethernet).  With a recent kernel 
> all TCP packets sent via sis0 have a bad checksum.  Other systems using other 
> interface types (though I don't have a broad selection to test) don't seem to 
> suffer from this problem.

how do you see the bad checksum? Are you running tcpdump on that sis
interface or did you have "invalid packets" on the remote machine?

If it's the former that's because of hardware checksumming and you
should be able to ignore it.

You can try
 	ifconfig sis0 -txcsum
and tcpdump would be fine again but the soekris cpu itself would
compute the checksum then.


Bjoern A. Zeeb                                 bzeeb at Zabbadoz dot NeT
Software is harder than hardware  so better get it right the first time.

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