From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758971AbXH3Mlw (ORCPT ); Thu, 30 Aug 2007 08:41:52 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755586AbXH3Mln (ORCPT ); Thu, 30 Aug 2007 08:41:43 -0400 Received: from extu-mxob-1.symantec.com ([216.10.194.28]:47500 "EHLO extu-mxob-1.symantec.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752871AbXH3Mlm (ORCPT ); Thu, 30 Aug 2007 08:41:42 -0400 Date: Thu, 30 Aug 2007 13:40:25 +0100 (BST) From: Hugh Dickins X-X-Sender: hugh@blonde.wat.veritas.com To: Roman Zippel cc: Sam Ravnborg , Michal Piotrowski , linux-kernel@vger.kernel.org, kbuild-devel@lists.sourceforge.net Subject: Re: CONFIG_HOTPLUG_CPU: kconfig bug? In-Reply-To: Message-ID: References: <20070827172654.GA21871@uranus.ravnborg.org> <20070829180158.GA7849@uranus.ravnborg.org> 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 On Thu, 30 Aug 2007, Roman Zippel wrote: > > > > > > I've noticed an oddity with CONFIG_HOTPLUG_CPU in 2.6.23-rc: > > > > > make oldconfig seems to turn it on even when nothing wants it, > > > > > increasing kernel size by about 10k; but if you then edit the > > > > > line out of .config and make oldconfig again, it correctly > > > > > offers the choice and lets it be turned off after all. > > It's somewhat a side effect of using select and defaults, the order of the > config symbols becomes significant for oldconfig, if you look at the > output you'll find: > > Support for suspend on SMP and hot-pluggable CPUs (EXPERIMENTAL) (HOTPLUG_CPU) [Y/?] y > > this sets it to 'y'. In this case one isn't asked about it, because there > is only one choice. The patch below avoids the setting of the value here. Thanks for working that out: your patch certainly works for me, and would be good to see in 2.6.23, to prevent lots of users getting an unnecessary CONFIG_HOTPLUG_CPU forever after. I wonder what config options this might have forced in the past. > > Avoid setting the value if the symbol doesn't need to be changed or can't > be changed. Later choices may change the dependencies and thus the > possible input range. > > Signed-off-by: Roman Zippel But please add a sentence to your patch description, something like: make oldconfig from a 2.6.22 .config with CONFIG_HOTPLUG_CPU not set was in some configurations setting CONFIG_HOTPLUG_CPU=y without asking, even when there was no actual requirement for CONFIG_HOTPLUG_CPU. Thanks, Hugh