From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Kiszka Subject: Re: [PATCH] cpu hotplug issue Date: Thu, 21 Jul 2011 14:35:09 +0200 Message-ID: <4E281CFD.2030805@siemens.com> References: <20110720083507.GS2400@redhat.com> <4E2819EF.1040301@siemens.com> <20110721122559.GG3044@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Vasilis Liaskovitis , "kvm@vger.kernel.org" To: Gleb Natapov Return-path: Received: from goliath.siemens.de ([192.35.17.28]:18401 "EHLO goliath.siemens.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752064Ab1GUMfP (ORCPT ); Thu, 21 Jul 2011 08:35:15 -0400 In-Reply-To: <20110721122559.GG3044@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On 2011-07-21 14:25, Gleb Natapov wrote: > On Thu, Jul 21, 2011 at 02:22:07PM +0200, Jan Kiszka wrote: >> On 2011-07-21 13:06, Vasilis Liaskovitis wrote: >>> More precisely: To enable cpu-hotplug at each bisect stage, I apply >>> this patch derived from: >>> http://lists.gnu.org/archive/html/qemu-devel/2010-08/msg00850.html >>> >>> diff --git a/hw/qdev.c b/hw/qdev.c >>> index 1aa1ea0..aed48ce 100644 >>> --- a/hw/qdev.c >>> +++ b/hw/qdev.c >>> @@ -327,6 +327,7 @@ BusState *sysbus_get_default(void) >>> if (!main_system_bus) { >>> main_system_bus = qbus_create(&system_bus_info, NULL, >>> "main-system-bus"); >>> + main_system_bus->allow_hotplug = 1; >> >> BTW, this reminds me why "fixing" CPU hotplug won't help a lot. We > I do not see relation between qdev not allowing cpu hotplug bug It's not a bug, it's a feature: The system bus we attach APICs to so far is a statically configured beast, intentionally hotplug-incapable. Hacking this away in qemu-kvm will be a step towards where we came from and will break sooner or later again. We need a CPU/APIC bus, also for other reasons, that can then be made hotplug-capable. > and cpu been > created with incorrect state bug. Fixing of former will not magically > make later disappear. Both should be solved. The issues hidden by the topology design problem should be solved nevertheless, that's true. Jan -- Siemens AG, Corporate Technology, CT T DE IT 1 Corporate Competence Center Embedded Linux