From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rick Jones Subject: Re: expected behavior of PF_PACKET on NETIF_F_HW_VLAN_RX device? Date: Thu, 01 Nov 2007 16:26:01 -0700 Message-ID: <472A6089.7020104@hp.com> References: <472A49BD.6000802@hp.com> <20071101.145956.63020380.davem@davemloft.net> <472A4D5C.2070301@hp.com> <20071101.150723.30590053.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Cc: djohnson+linux-kernel@sw.starentnetworks.com, greearb@candelatech.com, shemminger@linux-foundation.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, bguo@sw.starentnetworks.com To: David Miller Return-path: Received: from palrel11.hp.com ([156.153.255.246]:45554 "EHLO palrel11.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754620AbXKAX0F (ORCPT ); Thu, 1 Nov 2007 19:26:05 -0400 In-Reply-To: <20071101.150723.30590053.davem@davemloft.net> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org David Miller wrote: > From: Rick Jones >>I'll try to go pester folks in tcpdump-workers then. > > > The thing to check is "TP_STATUS_CSUMNOTREADY". > > When using mmap(), it will be provided in the descriptor. When using > recvmsg() it will be provided via a PACKET_AUXDATA control message > when enabled via the PACKET_AUXDATA socket option. Figures... the "dailies" and "weeklies" for tar files of tcpdump and libpcap source are fubar... again. I've email in to tcpdump-workers on that one. If that isn't resolved quickly I'll learn how to access their CVS (pick an SCM, any SCM...) I did an apt-get of debian lenny's tcpdump and sources: hpcpc103:~# tcpdump -V tcpdump version 3.9.8 libpcap version 0.9.8 and that seems to show the false checksum failure and not use the TP_STATUS_CSUMNOTREADY - at least that didn't appear in a grepping of the sources. At first I thought it might be, but then I realized that my snaplen was too short to get the whole TSO'ed frame so tcpdump wasn't even trying to verify. After disabling TSO on the NIC, leaving CKO on, and making my snaplen > 1500 I could see it was doing undesirable stuff. I'll see what top of trunk has at some point and what the folks there think of adding-in a change. rick jones