From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263516AbTDCUrB (for ); Thu, 3 Apr 2003 15:47:01 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263530AbTDCUrB (for ); Thu, 3 Apr 2003 15:47:01 -0500 Received: from [207.103.213.66] ([207.103.213.66]:64784 "EHLO sandman.sandgate.com") by vger.kernel.org with ESMTP id S263516AbTDCUq7 (for ); Thu, 3 Apr 2003 15:46:59 -0500 From: "Dennis Cook" To: "Jeff Garzik" Cc: , Subject: RE: Deactivating TCP checksumming Date: Thu, 3 Apr 2003 15:57:53 -0500 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook IMO, Build 9.0.6604 (9.0.2911.0) Importance: Normal In-Reply-To: <3E8C9DDD.3080205@pobox.com> X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org In the 3c59x.c, e1000, and other adapter drivers, ip_summed is what is being checked for value CHECKSUM_HW when sending a packet. > -----Original Message----- > From: Jeff Garzik [mailto:jgarzik@pobox.com] > Sent: Thursday, April 03, 2003 03:47 PM > To: Dennis Cook > Cc: linux-kernel@vger.kernel.org; kernelnewbies@nl.linux.org > Subject: Re: Deactivating TCP checksumming > > > Dennis Cook wrote: > > Based on various feedback, on my RH Linux 2.4.18 kernel I tried the > > following: > > > > Set "features" bit NETIF_F_IP_CSUM set (the only feature bit set). > > In my network driver start-transmit check for "CHECKSUM_HW" in > ip_summed. > > Using a small test program, use "sendfile" to copy a file to a network > > socket FD. > > Result is none of the packets presented to my network adapter > driver have > > ip_summed set to CHECKSUM_HW, so the SW IP stack has already > > computed checksums. > > CHECKSUM_HW is for receive, not transmit. Read the comments at the top > of include/linux/skbuff.h. > > > > Is this mechanism possibly broken on kernel 2.4? > > > it works quite well. > > Jeff > > > >