From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752524AbYIBKX3 (ORCPT ); Tue, 2 Sep 2008 06:23:29 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751090AbYIBKXU (ORCPT ); Tue, 2 Sep 2008 06:23:20 -0400 Received: from NAT-170.Local.iNES.RO ([80.86.100.170]:46430 "EHLO blade.ines.ro" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751033AbYIBKXT (ORCPT ); Tue, 2 Sep 2008 06:23:19 -0400 Subject: Re: IRQ routing / assignment issue From: Radu Rendec To: Robert Hancock Cc: linux-kernel@vger.kernel.org In-Reply-To: <48BC248E.702@shaw.ca> References: <48BC248E.702@shaw.ca> Content-Type: text/plain Date: Tue, 02 Sep 2008 13:23:13 +0300 Message-Id: <1220350993.16764.27.camel@blade.ines.ro> Mime-Version: 1.0 X-Mailer: Evolution 2.12.3 (2.12.3-5.fc8) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2008-09-01 at 11:21 -0600, Robert Hancock wrote: > The kernel doesn't really have any way to change the physical > device/slot to IRQ mapping. In some cases there are BIOS settings which > might influence this, but in most cases it's impossible to change (i.e. > devices physically wired to the same IRQ line). Thanks for your quick reply. I know there are 4 physical interrupt lines, interleaved for the many devices connected to a bus, so that, if most of the devices issue INTA, the interrupts are actually asserted on different pins of the apic (an almost uniform distribution of the interrupts, but still, two devices can share the same physical line). I also know that it's possible to change the (logical) irq levels assigned to physical INTA-INTD (perhaps using the pirq= parameter). As I have limited knowledge of hardware implementations, I'm asking you if it's usual/possible for a dual-processor system to have the same physical irq pin connected to the same irq line of _different_ pci buses. To put it in other words, is it possible for two devices on _separate_ pci buses to physically share the same irq pin? Thanks, Radu Rendec