Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757848AbYAQVTR (ORCPT ); Thu, 17 Jan 2008 16:19:17 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755562AbYAQVTE (ORCPT ); Thu, 17 Jan 2008 16:19:04 -0500 Received: from mail-dub.bigfish.com ([213.199.154.10]:48045 "EHLO mail180-dub-R.bigfish.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751711AbYAQVTD (ORCPT ); Thu, 17 Jan 2008 16:19:03 -0500 X-BigFish: VP X-MS-Exchange-Organization-Antispam-Report: OrigIP: 139.95.251.8;Service: EHS X-Server-Uuid: C391E81C-6590-4A2B-9214-A04D45AF4E95 Date: Thu, 17 Jan 2008 14:19:17 -0700 From: "Jordan Crouse" To: "Arnd Hannemann" cc: "Andres Salomon" , linux-kernel@vger.kernel.org Subject: Re: 2.6.24-rc8 hangs at mfgpt-timer Message-ID: <20080117211917.GF8244@cosmic.amd.com> References: <478E4267.7020509@i4.informatik.rwth-aachen.de> <20080116161912.7b449466@ephemeral> <20080116165606.3ebc06a4@ephemeral> <478F25D6.3060503@i4.informatik.rwth-aachen.de> <20080117134032.4cc1a1cf@ephemeral> <478FB255.5040001@i4.informatik.rwth-aachen.de> MIME-Version: 1.0 In-Reply-To: <478FB255.5040001@i4.informatik.rwth-aachen.de> User-Agent: Mutt/1.5.15+20070412 (2007-04-11) X-OriginalArrivalTime: 17 Jan 2008 21:18:45.0823 (UTC) FILETIME=[8B3A3CF0:01C8594E] X-WSS-ID: 6B9119BC2IW8047173-01-01 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4270 Lines: 106 On 17/01/08 20:53 +0100, Arnd Hannemann wrote: > Andres Salomon schrieb: > > On Thu, 17 Jan 2008 10:54:30 +0100 > > Arnd Hannemann wrote: > > > >> Andres Salomon schrieb: > >>> On Wed, 16 Jan 2008 16:19:12 -0500 > >>> Andres Salomon wrote: > >>> > >>>> On Wed, 16 Jan 2008 18:44:07 +0100 > >>>> Arnd Hannemann wrote: > >>>> > >>>>> Hi, > >>>>> > >>>>> I'm trying to boot 2.6.24-rc8 on a GEODE LX board (ALIX.3), > >>>>> and it hangs during boot: > >>>>> > >>>>> [ 12.689971] NET: Registered protocol family 16 > >>>>> [ 12.703329] geode-mfgpt: Registered timer 0 > >>>>> [ 12.716149] mfgpt-timer: registering the MFGT timer as a clock event... > >>>>> > >>>> What BIOS are you using? It's possible that our detection code is > >>>> failing to detect in-use timers. > >> I'm using v0.99 (latest available). > > > > > > v0.99 of what? Jordan seems to think it's an Award BIOS, but I'd like > > to make sure. > > Its an ALIX board from PCEngines, they have their own BIOS > implementation (tinyBios). > http://www.pcengines.ch/alix.htm > > > > >> Also note when I do enable the mysterios "MFGPT workaround" option in > >> the bios the machine hangs directly after: > >> [ 36.780990] NET: Registered protocol family 16 > > > > > > "MFGPT workaround"? That sounds a bit frightening. > > > > Presumably, the BIOS is using the MFGPTs, but we're not detecting them as > > being in use. > Yes I think so too, for the fun of it I compiled a 2.6.16.29 kernel with > the attached patch from fi4l. Okay - thats an MFPGT patch from pre-OLPC days. I am the guilty and dubious party. We changed the API to work better with the timer tick, and thats the version that ended up in the kernel. I really wish I could take back this patch, because it keeps coming back to torment me. We must, as a people, put it behind us and forgot it. :) > relevant output is this: > [ 31.015425] geode-mfgpt: 7 timers available. > ... > [ 31.245875] geode-mfgpt: Registered timer 0 > So the above kernel detects only 7 timers not 8, and it works. But note > that timer 0 is not used as a clock event source but as a watchdog, > which btw actually works fine :-) It detects 7 timers because of a bug in the code - there really are 8 timers, which the current code correctly identifies. > The funny thing is the #define workaround part of this dubious patch and > its interaction with the bios: > > #ifdef WORKAROUND: > I have to turn the "MFPGT workaround" option in the bios ON, to boot > the kernel probably. > > #ifndef WORKAROUND: > I have to turn the "MFPGT workaround" option in the bios OFF, to boot > the kernel probably. So the workaround works around the workaround. Fun. I think that Mitch Bradley verified that if you write the magic MSR when all the clocks are already clear that bad things happen. The workaround probably adds a dummy clock in. Notice that the "magic MSR" no longer is in the vanilla code, and thats the way it should be. If the BIOS doesn't allow use of the clocks, then we have to live with that. So, based on everything you are saying, I think its clear that our problem isn't in the MFGPT, but rather in the timer tick (because, as you said, the watchdog works). We try to use IRQ 7 for the tick, which Andres and I totally plucked out of thin air based on what we had to work with on OLPC. Its totally possible that the TinyBIOS had other ideas. Please try to boot with nomfgpt, and see which interrupts are free, and use mfgpt_irq= to change it to something else if 7 is in use. Based on your findings above, you'll probably need to leave the MFGPT workaround off from now on. I'll port the watchdog timer to the new API, and we can use that instead of the timer tick to just make sure that it isn't the timer that is broken. Also, hopefully that will cease the stream of angry emails asking me why the ancient patch doesn't work on a current kernel... :) Jordan -- 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/