Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754460AbYGGODD (ORCPT ); Mon, 7 Jul 2008 10:03:03 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752862AbYGGOCx (ORCPT ); Mon, 7 Jul 2008 10:02:53 -0400 Received: from kirk.serum.com.pl ([213.77.9.205]:63953 "EHLO serum.com.pl" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750804AbYGGOCw (ORCPT ); Mon, 7 Jul 2008 10:02:52 -0400 Date: Mon, 7 Jul 2008 15:01:31 +0100 (BST) From: "Maciej W. Rozycki" To: "Rafael J. Wysocki" cc: Ingo Molnar , Matthew Garrett , Len Brown , Thomas Gleixner , linux-next@vger.kernel.org, linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org, Andi Kleen Subject: Re: [PATCH 2/2] acpi: Disable IRQ 0 through I/O APIC for some HP systems In-Reply-To: <200807071423.48425.rjw@sisk.pl> Message-ID: References: <20080707071706.GA3326@elte.hu> <200807071423.48425.rjw@sisk.pl> 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: 1463 Lines: 28 On Mon, 7 Jul 2008, Rafael J. Wysocki wrote: > > It makes absolutely no sense and should be harmful to call > > clear_IO_APIC_pin(apic1, pin1) here, because both apic1 and pin1 should be > > equal to -1 here. If it has to be called, then I suppose the DMI matching > > did not work and the workaround has not been enabled. > > Do you realize that the clear_IO_APIC_pin(apic1, pin1) thing is _only_ called > _IF_ the DMI matching did work? Well, it is the very intent of the DMI quirk to set apic1 and pin1 both to -1, as a result of IRQ0 being absent from our I/O APIC interrupt routing table. Therefore if the quirk did indeed work, a call to clear_IO_APIC_pin() is useless and likely harmful as its callees don't do range checking (my understanding of code is it results in random poking at the local APIC through the FIX_APIC_BASE fixmap). There should be nothing to clear too, as interrupt redirection entries for all the I/O APIC inputs are cleared (the mask is set to 1 and the remaining fields zeroed) when clear_IO_APIC() is called from enable_IO_APIC() upon initialization and all the unused ones (not referred to from anywhere in the interrupt routing table) are never touched afterwards. 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/