From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Fri, 24 Aug 2001 04:03:21 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Fri, 24 Aug 2001 04:03:13 -0400 Received: from hermine.idb.hist.no ([158.38.50.15]:41732 "HELO hermine.idb.hist.no") by vger.kernel.org with SMTP id ; Fri, 24 Aug 2001 04:03:02 -0400 Message-ID: <3B8609EF.789D99F5@idb.hist.no> Date: Fri, 24 Aug 2001 10:01:51 +0200 From: Helge Hafting X-Mailer: Mozilla 4.76 [en] (X11; U; Linux 2.4.9 i686) X-Accept-Language: no, en MIME-Version: 1.0 To: cwidmer@iiic.ethz.ch, linux-kernel@vger.kernel.org Subject: Re: hardware checksumming In-Reply-To: <200108231458.f7NEwqk24604@mail.swissonline.ch> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Christian Widmer wrote: > yes that might be easy for the NIC's transmitting enging when all fragments > belonging together come one after the other in the transmit-ring. > but receiving is difficult since different connections can arrive > simultanously and reslut in interleaved framgents. > > something else: you need quite a lot of ram on the NIC to buffer fragments. > if not it will have to transfer the data twice through the PCI (checksumm are > at the beginig of a packet not the end). nobody did spend a second on > thinking to implement all in hardware when the interet protokol was desinged. You don't have to store entire fragments in a NIC to do hw checksums. All you need to store is the partial checksums, and add to them whenever yet another fragment comes in for that packet. Helge Hafting