Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750866AbWECUhr (ORCPT ); Wed, 3 May 2006 16:37:47 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750859AbWECUhr (ORCPT ); Wed, 3 May 2006 16:37:47 -0400 Received: from teetot.devrandom.net ([66.35.250.243]:14532 "EHLO teetot.devrandom.net") by vger.kernel.org with ESMTP id S1750841AbWECUhq (ORCPT ); Wed, 3 May 2006 16:37:46 -0400 Date: Wed, 3 May 2006 13:37:40 -0700 From: thockin@hockin.org To: Tim Small Cc: Alan Cox , "Ong, Soo Keong" , "Gross, Mark" , bluesmoke-devel@lists.sourceforge.net, LKML , "Carbonari, Steven" , "Wang, Zhenyu Z" Subject: Re: Problems with EDAC coexisting with BIOS Message-ID: <20060503203740.GA17515@hockin.org> References: <1145888979.29648.56.camel@localhost.localdomain> <4459119D.10905@buttersideup.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4459119D.10905@buttersideup.com> User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1313 Lines: 27 On Wed, May 03, 2006 at 09:25:01PM +0100, Tim Small wrote: > existing BIOSs, but the EDAC module could reprogram the chipset > error-signalling registers, so that an ECC error no longer triggers an This is key, I think. > SMI. The BIOS SMI handler could then read the signalling registers, and > leave the ECC registers well alone if ECC errors are not set to generate > an SMI. The fundamental problem with SMI is that we CAN'T know what it is doing. I've seen systems which trigger SMI from a GPIO toggled by a clock. I've seen systems trigger SMI from a chipset-internal periodic timer. I've seen chipsets route NMI->SMI or even MCE->SMI. If the BIOS is polling the error status registers from a periodic SMI, we're GOING to lose data. The big hammer - turn off SMI - is probably OK on some systems, but is not a general solution. More and more hardware workarounds and features are SMI based. There are some rather interesting things that can be done in SMM, *iff* we could get the BIOS out of the way. Tim (watching EDAC from time to time, quietly) - 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/