Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754264AbZAMAak (ORCPT ); Mon, 12 Jan 2009 19:30:40 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752235AbZAMAa3 (ORCPT ); Mon, 12 Jan 2009 19:30:29 -0500 Received: from mx2.redhat.com ([66.187.237.31]:33053 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752218AbZAMAa2 (ORCPT ); Mon, 12 Jan 2009 19:30:28 -0500 Subject: Re: PCI, ACPI, IRQ, IOAPIC: reroute PCI interrupt to legacy boot interrupt equivalent From: Jon Masters To: "Eric W. Biederman" Cc: Bjorn Helgaas , Stefan Assmann , Len Brown , Ingo Molnar , Jesse Barnes , Olaf Dabrunz , Thomas Gleixner , Steven Rostedt , Linux Kernel Mailing List , linux-acpi@vger.kernel.org, Sven Dietrich , "Maciej W. Rozycki" In-Reply-To: References: <496B24E5.1070804@suse.de> <200901121151.53195.bjorn.helgaas@hp.com> Content-Type: text/plain Organization: Red Hat, Inc. Date: Mon, 12 Jan 2009 19:29:23 -0500 Message-Id: <1231806563.4094.25.camel@perihelion.bos.jonmasters.org> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 950 Lines: 24 On Mon, 2009-01-12 at 15:36 -0800, Eric W. Biederman wrote: > This hardware behavior is not specific to boot interrupts or Intel. It's not specific to Intel, but it is a specific compatibility behavior. > Is this case really so interesting and compelling that we want to fight > through and figure what we need to do to make this work reliably on every > x86 chipset? How else do you propose implementing IRQ handling in e.g. the RT kernel? We get a hardware interrupt, we can't FastEOI, we can't process synchronously, we can't do all of those things you might expect. Implementing RT requires that we delay handling of the IRQ until arbitrarily later in the future when we get around to it. Jon. -- 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/