Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754647AbYJFU7s (ORCPT ); Mon, 6 Oct 2008 16:59:48 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752173AbYJFU7k (ORCPT ); Mon, 6 Oct 2008 16:59:40 -0400 Received: from one.firstfloor.org ([213.235.205.2]:37272 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751761AbYJFU7j (ORCPT ); Mon, 6 Oct 2008 16:59:39 -0400 To: "Maciej W. Rozycki" Cc: Ingo Molnar , Linus Torvalds , "Rafael J. Wysocki" , Dmitry Torokhov , linux-kernel@vger.kernel.org, Andrew Morton , Len Brown , Jason Vas Dias Subject: Re: [PATCH] x86 ACPI: Blacklist two HP machines with buggy BIOSes (Re: 2.6.27-rc8+ - first impressions) From: Andi Kleen References: <20081005183603.GA3263@amd.corenet.prv> <200810060029.42471.rjw@sisk.pl> <20081006062235.GA2808@amd.corenet.prv> <200810061159.30103.rjw@sisk.pl> <20081006150055.GA16930@elte.hu> Date: Mon, 06 Oct 2008 22:59:37 +0200 In-Reply-To: (Maciej W. Rozycki's message of "Mon, 6 Oct 2008 18:51:20 +0100 (BST)") Message-ID: <87tzbpmocm.fsf@basil.nowhere.org> User-Agent: Gnus/5.1008 (Gnus v5.10.8) Emacs/21.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1347 Lines: 27 "Maciej W. Rozycki" writes: > > This single instance of a piece of some HP gear being twisted beyond > belief is IMO a minor annoyance and price to pay compared to the gain. > Please note that apart from the DSDT being buggy on this machine, it has > an incorrect IRQ 0 override in the ACPI table pointing to the pin #2 of > the I/O APIC, which is in fact routed to the output of the master 8259A. > Additionally the pin #0 of the I/O APIC which is indeed routed to the > output of the 8254 does not receive any interrupts, presumably because of > some misconfiguration during BIOS initialisation. The real reason is actually a workaround in the BIOS for problems in the older Linux code that caused duplicated timer interrupts. The old Linux would fall into "enable both IO-APIC and 8259" fallback mode and the resulted in duplicated timer events, which made everything unhappy. They instead configured the northbridge in a way that one of the inputs is ignored. You won't be able to DMI list it, that workaround is widely used in lots of different systems. -andi -- 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/