Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1763527AbXFATuM (ORCPT ); Fri, 1 Jun 2007 15:50:12 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1762504AbXFATuA (ORCPT ); Fri, 1 Jun 2007 15:50:00 -0400 Received: from ebiederm.dsl.xmission.com ([166.70.28.69]:47683 "EHLO ebiederm.dsl.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1762410AbXFATt7 (ORCPT ); Fri, 1 Jun 2007 15:49:59 -0400 From: ebiederm@xmission.com (Eric W. Biederman) To: "Rafael J. Wysocki" Cc: Robert Hancock , Andrew Morton , Andi Kleen , linux-kernel@vger.kernel.org, Neil Brown , Ingo Molnar , Zwane Mwaikambo Subject: Re: [PATCH] x86: Document the hotplug code is incompatible with x86 irq handling References: <465EDCF4.7010700@shaw.ca> <200705312212.34053.rjw@sisk.pl> Date: Fri, 01 Jun 2007 13:48:29 -0600 In-Reply-To: <200705312212.34053.rjw@sisk.pl> (Rafael J. Wysocki's message of "Thu, 31 May 2007 22:12:33 +0200") Message-ID: User-Agent: Gnus/5.110006 (No Gnus v0.6) Emacs/21.4 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1786 Lines: 43 "Rafael J. Wysocki" writes: >> Cool. >> >> My patch does not change the functionality of the code just complains >> very loudly that it is broken. >> >> Further the code is broken at a design level. The code isn't >> problematic the code is impossible. The cpu hotplug code can not be >> fixed on x86 without a redesign of the generic cpu hotplug code. >> >> Suspend does not need to use cpu hotplug because it already gets in >> deep with the drivers, and can stop interrupts at the source. I know >> there was some talk about this doing this earlier, but I don't know if >> anything came of that discussion. >> >> Regardless if you care about this being a problem feel free to fix the >> relevant code so it attempts to do something that the hardware >> actually supports. >> >> But if the suspend needs this code for smp support it is also broken. > > Well, from the functionality point of view, it's not. We have no problems > with it, at least not that I know of. Luck, or enough other issues someone hasn't tracked their problems down to this. On the pure cpu hotplug path I just got a bug report about it not working: http://lkml.org/lkml/2007/5/31/419 So apparently real people can hit this one. Not just theoretical people seen by code reviewers. The code is broken by design and cannot be made to support existing x86 SMP systems. Please find a way to use something that works. The suspend path is already talking to the drivers and can stop IRQs at their source so it should not be a big deal. Eric - 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/