Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751264AbWC3DZL (ORCPT ); Wed, 29 Mar 2006 22:25:11 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751269AbWC3DZL (ORCPT ); Wed, 29 Mar 2006 22:25:11 -0500 Received: from smtp.osdl.org ([65.172.181.4]:35510 "EHLO smtp.osdl.org") by vger.kernel.org with ESMTP id S1751264AbWC3DZK (ORCPT ); Wed, 29 Mar 2006 22:25:10 -0500 Date: Wed, 29 Mar 2006 19:24:53 -0800 From: Andrew Morton To: Ashok Raj Cc: pavel@ucw.cz, linux-kernel@vger.kernel.org, ashok.raj@intel.com Subject: Re: [rfc] fix Kconfig, hotplug_cpu is needed for swsusp Message-Id: <20060329192453.538a131d.akpm@osdl.org> In-Reply-To: <20060329150950.A12482@unix-os.sc.intel.com> References: <20060329220808.GA1716@elf.ucw.cz> <20060329144746.358a6b4e.akpm@osdl.org> <20060329150950.A12482@unix-os.sc.intel.com> X-Mailer: Sylpheed version 1.0.4 (GTK+ 1.2.10; i386-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1728 Lines: 36 Ashok Raj wrote: > > On Wed, Mar 29, 2006 at 02:47:46PM -0800, Andrew Morton wrote: > > Pavel Machek wrote: > > > > > > HOTPLUG_CPU is needed on normal PCs, too -- it is neccessary for > > > software suspend. > > > > > > > OK, this will get ugly. APICs are involved. > > I guess you need only on systems that support >1 cpu right? I doubt you will need > it on a system that cannot run with the config-generic-arch on. although we use bigsmp > when hotplug is turned on, all we really end up is using flat physical mode instead > of using logical mode. > > I still havent understood why this wont work. Choosing CONFIG_X86_GENERICARCH shouldnt > break anything AFAICT. > > Pavel, you could use CONFIG_HOTPLUG_CPU, just need to enable X86_GENERICARCH now. > Is there a reason you think that wont work? I wish we would revert it for a strong > reason that we know will not make hotplug work on certain systems because of this choise > not that we currently have X86_PC now, and are unwiling to change the config. > > (PS: the word bigsmp although sounds like some large NR_CPUS, its just using a mode that > permits the system to work from 1 .. >8 cpus. So there is really nothing determental > to selecting this.) Something which remains to be beaten into my head: *why* does HOTPLUG_CPU require flat pyhsical mode? What necessitated that change, and cannot we make it work OK in logical mode as well as flat mode? - 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/