Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757334AbYFJTi2 (ORCPT ); Tue, 10 Jun 2008 15:38:28 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753856AbYFJTiU (ORCPT ); Tue, 10 Jun 2008 15:38:20 -0400 Received: from kirk.serum.com.pl ([213.77.9.205]:62850 "EHLO serum.com.pl" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753710AbYFJTiU (ORCPT ); Tue, 10 Jun 2008 15:38:20 -0400 Date: Tue, 10 Jun 2008 20:36:54 +0100 (BST) From: "Maciej W. Rozycki" To: Yinghai Lu cc: Glauber Costa , linux-kernel@vger.kernel.org, akpm@linux-foundation.org, tglx@linutronix.de, mingo@elte.hu, hugh@veritas.com Subject: Re: [PATCH 11/15] x86: move enabling of io_apic to prepare_cpus In-Reply-To: <86802c440806101209q301bcef0ia859db7e587bd42e@mail.gmail.com> Message-ID: References: <1213021018-14159-1-git-send-email-gcosta@redhat.com> <484D8813.4040807@redhat.com> <86802c440806091353m240ab7adocbaf5dacd15504f7@mail.gmail.com> <86802c440806092208s338cf6b6q892f5149bbd142ca@mail.gmail.com> <484E7B03.8000604@redhat.com> <86802c440806101209q301bcef0ia859db7e587bd42e@mail.gmail.com> 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: 1648 Lines: 35 On Tue, 10 Jun 2008, Yinghai Lu wrote: > kernel should not assume io apic register is set right by firmware. What is the basis of this assumption? Linux generally assumes the chipset components have been placed by the firmware into a consistent state. That does not necessarily mean suitable for Linux, hence the need to reconfigure a bit here or there, but there should be no need to touch components that are not going to be used by Linux directly. The I/O APIC is no different. > and kernel actually doesn't trust them, and clear the io apic registers. The I/O APIC registers are cleared, because this is the only way you can assure inconsistent configuration does not happen during reconfiguration. For example two inputs using the same vector or set up into the ExtINTA mode. The original intent of the code was not to paper over breakage in the firmware. You are trying to change it and it can be done, but it has to be justified well. > that patch just move that early before enable error vector. What I am saying repeatedly is clearing of the I/O APIC is not guaranteed to happen for all the possible cases of Linux configuration. Which means this is a partial solution only -- please try to propose a better one or provide the original problem report so that someone else can have a look at it. What's triggering the error interrupt for example? Is it recoverable? Maciej -- 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/