Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932444AbWJFQjN (ORCPT ); Fri, 6 Oct 2006 12:39:13 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932442AbWJFQjN (ORCPT ); Fri, 6 Oct 2006 12:39:13 -0400 Received: from srv5.dvmed.net ([207.36.208.214]:11938 "EHLO mail.dvmed.net") by vger.kernel.org with ESMTP id S932439AbWJFQjL (ORCPT ); Fri, 6 Oct 2006 12:39:11 -0400 Message-ID: <452686A3.9050004@garzik.org> Date: Fri, 06 Oct 2006 12:38:59 -0400 From: Jeff Garzik User-Agent: Thunderbird 1.5.0.7 (X11/20060913) MIME-Version: 1.0 To: Linus Torvalds CC: David Howells , linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, Ingo Molnar , Alan Cox , Andrew Morton , Thomas Gleixner , Dmitry Torokhov , Greg KH , David Brownell , Alan Stern Subject: Re: [PATCH, RAW] IRQ: Maintain irq number globally rather than passing to IRQ handlers References: <20061002132116.2663d7a3.akpm@osdl.org> <20061002162049.17763.39576.stgit@warthog.cambridge.redhat.com> <20061002162053.17763.26032.stgit@warthog.cambridge.redhat.com> <18975.1160058127@warthog.cambridge.redhat.com> <4525A8D8.9050504@garzik.org> <1160133932.1607.68.camel@localhost.localdomain> <45263ABC.4050604@garzik.org> <20061006111156.GA19678@elte.hu> <45263D9C.9030200@garzik.org> <452673AC.1080602@garzik.org> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Score: -4.3 (----) X-Spam-Report: SpamAssassin version 3.1.3 on srv5.dvmed.net summary: Content analysis details: (-4.3 points, 5.0 required) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2247 Lines: 50 Linus Torvalds wrote: > > On Fri, 6 Oct 2006, Jeff Garzik wrote: >> Here is the raw, un-split-up first pass of the irq argument removal patch >> (500K): http://gtf.org/garzik/misc/patch.irq-remove > > So I'm not at all as sure about this as about the "regs" stuff. > > The "regs" value has always been controversial. It's pretty much always > existed (due to the keyboard hander and the magic debugging keysequences), > and anybody who looks at 0.01 will quickly realize that the keyboard > driver was one of the very first drivers (I think it's even written in > assembly at that point: originally _all_ of what was to become Linux was > pure asm, the whole "oh, cool, I could write this part in C" came later). > But it's been pretty much a special case since day #1, purely for that > "press a key to see where the h*ck we hung" case. Chuckle :) > In contrast, the irq argument itself is really no different from the > cookie we pass in on registration - it's just passing it back to the > driver that requested the thing. So unlike "regs", there's not really > anything strange about it, and there's nothing really "wrong" with having > it there. It doesn't have the colorful history of pt_regs, but the 'irq' argument is dead weight. I'd say the wrongness stems from its utter uselessness. Out of ~1100 irq handlers, the irq parameter is used in ~50. The vast majority of those 50 uses are debug printks, or abused as a "did I call myself?" internal driver flag. The number of "real" uses is under 15, and those are all ancient ISA or platform drivers that pre-date my ~10 year history with Linux. So, I don't see any convincing argument to keep it. And if we are going to kill it, given the pt_regs churn, this is probably the best opportunity we'll have in years. Another weak-but-still-present argument in favor of killing it is that this change would IMO future-proof irq handlers, against more exotic irq handling methods that may come down the pipe. Jeff - 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/