From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ben Greear Subject: Problem with cxgb, mac-vlans, and UDP checksum offloading. Date: Tue, 11 Dec 2007 10:25:26 -0800 Message-ID: <475ED616.6070903@candelatech.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit To: Divy Le Ray , NetDev Return-path: Received: from ns2.lanforge.com ([66.165.47.211]:40609 "EHLO ns2.lanforge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752382AbXLKSZg (ORCPT ); Tue, 11 Dec 2007 13:25:36 -0500 Sender: netdev-owner@vger.kernel.org List-ID: Hello! This is with kernel 2.6.23, plus our hacks, but the mac-vlan logic is part of the official kernel now. OS is Fedora 8. I have applied patch 1 and 3 of those sent a few weeks ago for the cxgb as well. While testing NFS on mac-vlans on cxgb, we noticed that UDP packets have incorrect checksums when sent from the mac-vlan device on a cxgb interface to another system. When sending from a regular ethernet device (cxgb), it works fine. When we disable rx and tx UDP checksums on the mac-vlan device, it works fine. When we use e1000 interfaces (which also do rx/tx UDP checksumming), mac-vlans & NFS works fine with mac-vlan rx/tx checksumming on (the default value). So, there seems something weird about the cxgb NIC when used with mac-vlans. Perhaps it is somehow paying attention to MAC addresses when it determines if it should csum a packet or not? If you want to test it yourself, grab the latest iputils package and create MAC-VLANs like this: ip link add link eth0 name eth0#0 address 00:11:22:33:44:55 type macvlan If you would like a packet trace or any other debugging, please let me know. Thanks, Ben -- Ben Greear Candela Technologies Inc http://www.candelatech.com