Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Fri, 22 Feb 2002 18:52:50 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Fri, 22 Feb 2002 18:52:40 -0500 Received: from nat-pool-rdu.redhat.com ([66.187.233.200]:50319 "EHLO lacrosse.corp.redhat.com") by vger.kernel.org with ESMTP id ; Fri, 22 Feb 2002 18:52:29 -0500 Date: Fri, 22 Feb 2002 18:52:22 -0500 From: Benjamin LaHaise To: harish.vasudeva@amd.com Cc: linux-kernel@vger.kernel.org Subject: Re: Need some help with IP/TCP Checksum Offload Message-ID: <20020222185222.B16169@redhat.com> In-Reply-To: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5.1i In-Reply-To: ; from harish.vasudeva@amd.com on Fri, Feb 22, 2002 at 02:57:22PM -0800 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Feb 22, 2002 at 02:57:22PM -0800, harish.vasudeva@amd.com wrote: > > Then, in my start_xmit( ) routine, i am parsing for the right > headers & when i get the IP/TCP header, i print out the checksum > & it is already the right checksum. When does the OS/Protocol > offload this task? Am i missing something here? The network stack generates checksums for packets while copying, so the checksum offload feature is only used for packets that are not copied. The easiest way to generate packets of this nature is to use the sendfile() syscall to transmit data from the page cache directly onto the wire. If you need a couple of test programs I can forward a few to you offline. Cheers, -ben - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/