From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755484AbXLDWfj (ORCPT ); Tue, 4 Dec 2007 17:35:39 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754832AbXLDWfU (ORCPT ); Tue, 4 Dec 2007 17:35:20 -0500 Received: from einhorn.in-berlin.de ([192.109.42.8]:34716 "EHLO einhorn.in-berlin.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754098AbXLDWfS (ORCPT ); Tue, 4 Dec 2007 17:35:18 -0500 X-Envelope-From: stefanr@s5r6.in-berlin.de Message-ID: <4755D612.1090103@s5r6.in-berlin.de> Date: Tue, 04 Dec 2007 23:34:58 +0100 From: Stefan Richter User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.8.1.9) Gecko/20071122 SeaMonkey/1.1.6 MIME-Version: 1.0 To: Bernhard Kaindl CC: Benjamin Herrenschmidt , Andi Kleen , Bernhard Kaindl , linux-kernel@vger.kernel.org Subject: Re: remote debugging via FireWire * __fast__ firedump! References: <200702101242.48467.ak@suse.de> <45CDCDCD.5000609@s5r6.in-berlin.de> <4755D186.20204@s5r6.in-berlin.de> In-Reply-To: <4755D186.20204@s5r6.in-berlin.de> X-Enigmail-Version: 0.95.3 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Stefan Richter wrote: > Bernhard Kaindl wrote: >> The biggest block size that worked here was 2048 bytes, which was >> enough to get nearly 10MB/s of data transfer rate from the remote >> memory to disk. > > The maximum payload size of block requests depends on three things: > 1. speed of the connection between the two nodes (debugged machine and > debugging machine), 2. link layer controllers of the two nodes, 3. > software on the debugging machine. > > 1.) S100: 512 bytes, S200: 1024 bytes, S400: 2048 bytes, S800 and more: > 4096 bytes. PS: If there are only 1394a nodes, you can read the connection speed from the speed map registers on the debugging machine. It becomes difficult for 1394b nodes and some mixtures of 1394a and b nodes. But consumer 1394b hardware is always S800 capable. Consumer 1394a hardware is always S400 capable. Except consumer camcorders which are AFAIK typically limited to S100, but they have only one port and will therefore never sit between debugging and debugged PC. So it's not as difficult in 99.9% of the cases: You can expect S400, some people might get S800. But you can't use the bigger S800 block size if the debugging machine runs ohci1394. > 2.) Controllers on CardBus cards are limited to 1024 bytes payload of > asynchronous packets, for reasons I don't know. The other available > controllers only have the above mentioned speed-dependent limit. This is relevant if the debugging or the debugged PC have a CardBus card. Actually this is the limit of all 1394a CardBus card I have seen; I don't know about 1394b CardBus cards, or Express cards. (I suppose Express cards have no limits of this kind, as they are just PCIe cards in a different formfactor.) This payload limitation of the link can be read from the bus info blocks of the debugged and the debugging machine. Though I am not entirely sure right now if the ohci1394_earlyinit driven machine will have its bus info block properly set up. -- Stefan Richter -=====-=-=== ==-- --=-- http://arcgraph.de/sr/