From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263555AbTDCUfj (for ); Thu, 3 Apr 2003 15:35:39 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263558AbTDCUfj (for ); Thu, 3 Apr 2003 15:35:39 -0500 Received: from parcelfarce.linux.theplanet.co.uk ([195.92.249.252]:13531 "EHLO www.linux.org.uk") by vger.kernel.org with ESMTP id S263555AbTDCUfi (for ); Thu, 3 Apr 2003 15:35:38 -0500 Message-ID: <3E8C9DDD.3080205@pobox.com> Date: Thu, 03 Apr 2003 15:47:25 -0500 From: Jeff Garzik Organization: none User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.2.1) Gecko/20021213 Debian/1.2.1-2.bunk X-Accept-Language: en MIME-Version: 1.0 To: Dennis Cook CC: linux-kernel@vger.kernel.org, kernelnewbies@nl.linux.org Subject: Re: Deactivating TCP checksumming References: <20030401122824.GY29167@mea-ext.zmailer.org> <20030402203653.GA2503@gtf.org> <20030402205855.GA4125@gtf.org> In-Reply-To: Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org 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