From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757879AbZCBXf3 (ORCPT ); Mon, 2 Mar 2009 18:35:29 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755124AbZCBXfN (ORCPT ); Mon, 2 Mar 2009 18:35:13 -0500 Received: from earthlight.etchedpixels.co.uk ([81.2.110.250]:57518 "EHLO www.etchedpixels.co.uk" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754706AbZCBXfK (ORCPT ); Mon, 2 Mar 2009 18:35:10 -0500 Date: Mon, 2 Mar 2009 23:35:26 +0000 From: Alan Cox To: Peter Zijlstra Cc: David Brownell , Thomas Gleixner , Andrew Morton , me@felipebalbi.com, linux-kernel@vger.kernel.org, linux-input@vger.kernel.org, felipe.balbi@nokia.com, dmitry.torokhov@gmail.com, sameo@openedhand.com Subject: Re: lockdep and threaded IRQs (was: ...) Message-ID: <20090302233526.3c694e22@lxorguk.ukuu.org.uk> In-Reply-To: <1236028617.18955.14.camel@twins> References: <1235762883-20870-1-git-send-email-me@felipebalbi.com> <200903011454.22280.david-b@pacbell.net> <1235999772.5330.368.camel@laptop> <200903021304.56881.david-b@pacbell.net> <1236028617.18955.14.camel@twins> X-Mailer: Claws Mail 3.7.0 (GTK+ 2.14.7; x86_64-redhat-linux-gnu) Organization: None.. I'm free I'm free bwhahahahaha! Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > Because running irq handlers with irqs enabled it plain silly. It makes enormous sense to run with the ability to mask *just* the IRQ that occurred and not others so that long lasting interrupts. There is another reason not to do this of course - the real time work makes it essentially irrelevant by doing the job right and reducing the entire problem space to software priority management. > Except it turns out there is some really broken ass hardware out there. > But supposedly IDE PIO could be done from a threaded handler. Only if you support reliable masking of a single IRQ *after* the IRQ handler returns. The real time patches can do that for some chipsets but on the PC at least you are into the realms of deepest darkest APIC weirdness and that requires Ingo's pointy hat and wand.. Alan