From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757535AbXEaOes (ORCPT ); Thu, 31 May 2007 10:34:48 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752520AbXEaOel (ORCPT ); Thu, 31 May 2007 10:34:41 -0400 Received: from shawidc-mo1.cg.shawcable.net ([24.71.223.10]:24002 "EHLO pd4mo1so.prod.shaw.ca" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752478AbXEaOel (ORCPT ); Thu, 31 May 2007 10:34:41 -0400 Date: Thu, 31 May 2007 08:34:28 -0600 From: Robert Hancock Subject: Re: [PATCH] x86: Document the hotplug code is incompatible with x86 irq handling In-reply-to: To: "Eric W. Biederman" Cc: Andrew Morton , Andi Kleen , linux-kernel@vger.kernel.org, Neil Brown , "Rafael J. Wysocki" , Ingo Molnar , Zwane Mwaikambo Message-id: <465EDCF4.7010700@shaw.ca> MIME-version: 1.0 Content-type: text/plain; charset=ISO-8859-1; format=flowed Content-transfer-encoding: 7bit References: User-Agent: Thunderbird 2.0.0.0 (Windows/20070326) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Eric W. Biederman wrote: > I just realized that except for doing the code review and noticing > that the current cpu hotplug code is fundamentally incompatible > with x86 I haven't done anything about it. So here is my patch > to document what is wrong. > > The current cpu hotplug code requires irqs to be migrated from a cpu > outside of irq context. On x86 ioapics simply do not support this, > making the code unfixable without major redesign of the generic cpu > hotplug code. > > So this patch makes CPU_HOTPLUG on x86 depend on CONFIG_BROKEN > and adds a WARN_ON so people that do enable it are not in doubt about > which part of the code is broken, even if it does work for them. > > Signed-off-by: Eric W. Biederman I don't think this is useful, though the code may be problematic, this patch will break suspend on all SMP machines with an existing config, which is a major regression.. -- Robert Hancock Saskatoon, SK, Canada To email, remove "nospam" from hancockr@nospamshaw.ca Home Page: http://www.roberthancock.com/