From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752746AbZEKLTc (ORCPT ); Mon, 11 May 2009 07:19:32 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751506AbZEKLTX (ORCPT ); Mon, 11 May 2009 07:19:23 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:56839 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751024AbZEKLTX (ORCPT ); Mon, 11 May 2009 07:19:23 -0400 Date: Mon, 11 May 2009 13:19:04 +0200 From: Ingo Molnar To: Jeremy Fitzhardinge Cc: the arch/x86 maintainers , Linux Kernel Mailing List , Xen-devel , Jeremy Fitzhardinge Subject: Re: [PATCH 02/18] xen: hook io_apic read/write operations Message-ID: <20090511111904.GK4648@elte.hu> References: <1241730883-4917-1-git-send-email-jeremy@goop.org> <1241730883-4917-3-git-send-email-jeremy@goop.org> <20090509084201.GF3656@elte.hu> <20090509084324.GA5158@elte.hu> <4A05A408.3020006@goop.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4A05A408.3020006@goop.org> User-Agent: Mutt/1.5.18 (2008-05-17) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.3 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Jeremy Fitzhardinge wrote: >> And on a higher level, i still dont see why you dont do the whole >> Xen thing under an irqchip. There should be no extra crappy >> checks in native code. > > Hm, every time you see this code, you always have this > quasi-Pavlovian response. Yep, my reaction to ugly code is pretty predictable, and (hopefully!) repeatable. So calling it Pavlovian is an implicit (albeit, i suspect, unintended ;-) compliment. > You say "use an irqchip". I say: > > * We already use irqchip > * but most of the interesting IO apic accesses (routing) are not > done via the irqchip interface > * so irqchip doesn't help I dont see the problem. All APIs within Linux are kept minimalistic and are extended on the fly, on an on-demand basis. > And then you don't reply. And then you raise it again. > > I would *always* prefer to hook into an interface like irqchip > rather than gouge into the code, but I really think that irqchip > isn't that interface. If you have a more specific suggestion or > proposal I'll happily follow it up, but repeating "you should use > an irqchip" isn't getting anywhere. Well, my main task at this stage is to point out ugly code. I might be able to do research for you and come up with a plan for you, but that's really a courtesy in general and is not always possible for maintainers. You might argue "of all possible solutions this is the cleanest" but i havent seen you make that point. Ingo