Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262874AbUDALww (ORCPT ); Thu, 1 Apr 2004 06:52:52 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262876AbUDALww (ORCPT ); Thu, 1 Apr 2004 06:52:52 -0500 Received: from jurand.ds.pg.gda.pl ([153.19.208.2]:3745 "EHLO jurand.ds.pg.gda.pl") by vger.kernel.org with ESMTP id S262874AbUDALwu (ORCPT ); Thu, 1 Apr 2004 06:52:50 -0500 Date: Thu, 1 Apr 2004 13:52:48 +0200 (CEST) From: "Maciej W. Rozycki" To: Len Brown Cc: Ross Dickson , linux-kernel@vger.kernel.org, AMartin@nvidia.com, kernel@kolivas.org, Ian Kumlien Subject: Re: ACPI SCI IOAPIC bug (Re: Fixes for nforce2 hard lockup, apic, io-apic, udma133 covered) In-Reply-To: <1080771580.31359.32.camel@dhcppc4> Message-ID: References: <1080771580.31359.32.camel@dhcppc4> Organization: Technical University of Gdansk MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1740 Lines: 41 On Thu, 31 Mar 2004, Len Brown wrote: > Why is it that all IRQs get their name from the > IOAPIC pin number, but the timer connected to > pin 2 is called IRQ0 instead of IRQ2? ISA interrupts get their numbers from 8259A IRQ numbers they would be routed to in the PIC mode. This lets the code operate in the mixed mode sanely (which happens for certain hardware), although it's not necessarily the reason for the numbering used. Note that the MP Specification does not mandate an identity map of ISA interrupts, although it seems to be what vendors do. Also note that depending on the configuration, the timer can effectively be routed to INTIN2 or INTIN0 by Linux -- one of the alternatives being a direct connection and the other one being done through the 8259A configured to be transparent for its IRQ 0. > I wonder if we should't be moving to at least a build option which > deletes support for multiple pins at an IRQ, and deletes > suport for non-identity pin->IRQ mapping. This can't be done for the timer due to configuration variations. > While the ACPI table parsing is very early, the _PRT parsing > can happen only after the ACPI interpreter is up, because > the _PRT's are encoded in AML. Hmm, that's unfortunate. Couldn't the interpreter be started earlier? Maciej -- + Maciej W. Rozycki, Technical University of Gdansk, Poland + +--------------------------------------------------------------+ + e-mail: macro@ds2.pg.gda.pl, PGP key available + - 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/