Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757288AbZCJRHo (ORCPT ); Tue, 10 Mar 2009 13:07:44 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753764AbZCJRHf (ORCPT ); Tue, 10 Mar 2009 13:07:35 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:54298 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755413AbZCJRHf (ORCPT ); Tue, 10 Mar 2009 13:07:35 -0400 Date: Tue, 10 Mar 2009 18:07:16 +0100 From: Ingo Molnar To: Alan Stern Cc: prasad@linux.vnet.ibm.com, Andrew Morton , Linux Kernel Mailing List , Roland McGrath Subject: Re: [patch 06/11] Use virtual debug registers in process/thread handling code Message-ID: <20090310170716.GC22897@elte.hu> References: <20090310144933.GH3850@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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 Content-Length: 1864 Lines: 50 * Alan Stern wrote: > > Speaking of switch_to_thread_hw_breakpoint(), i dont like > > that function at all: > > > > - why does it have to do a list of debug registers? > > I'm not sure I understand the point of this question. Are you > asking why the hw_breakpoint structures are stored on a list? > Because there can be an arbitrarily large number of them. But that does not make much sense. There's just 4 hardware registers. There's no sane way to overcommit them hence we _should not_. > > - why does it worry about IPIs arriving when context-switches on > > x86 are always done with interrupts disabled? > > The routine gets invoked at times other than during a context > switch. However you may be right that these times are all > mutually exclusive. If so then a good deal of complication > can be removed. Yes. > > - also, what do the ->installed() and ->uninstalled() callbacks > > do - nothing uses it! > > What do you mean? They do what any callback does. And of > course nothing uses them -- the code hasn't been merged yet! No need to get testy - i'm the maintainer and you are trying to get stuff into two subsystems i maintain. I ask such questions when i see something added that has no immediate purpose. If a later patch needs a particular facility then submit it together with that use. It's not that hard to add callbacks - but right now it just distracts from the immediate purpose of these patches. And please dont try to get stuff merged if you are not willing to answer simple questions like that in a constructive way. Ingo -- 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/