Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932727AbWCVVBg (ORCPT ); Wed, 22 Mar 2006 16:01:36 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932730AbWCVVBf (ORCPT ); Wed, 22 Mar 2006 16:01:35 -0500 Received: from fmr17.intel.com ([134.134.136.16]:57744 "EHLO orsfmr002.jf.intel.com") by vger.kernel.org with ESMTP id S932727AbWCVVBe (ORCPT ); Wed, 22 Mar 2006 16:01:34 -0500 Date: Wed, 22 Mar 2006 13:00:55 -0800 From: Ashok Raj To: "Rafael J. Wysocki" Cc: Ashok Raj , akpm@osdl.org, Peter Williams , Linus Torvalds , Linux Kernel Mailing List , Pavel Machek Subject: Re: Linux v2.6.16 Message-ID: <20060322130055.A15217@unix-os.sc.intel.com> References: <200603221911.06576.rjw@sisk.pl> <20060322102717.A12901@unix-os.sc.intel.com> <200603222140.00912.rjw@sisk.pl> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5.1i In-Reply-To: <200603222140.00912.rjw@sisk.pl>; from rjw@sisk.pl on Wed, Mar 22, 2006 at 09:40:00PM +0100 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3009 Lines: 75 On Wed, Mar 22, 2006 at 09:40:00PM +0100, Rafael J. Wysocki wrote: > > > > with that patch, try > > > > CONFIG_X86_PC=n > > CONFIG_GENERICARCH=y > > CONFIG_HOTPLUG_CPU=y > > Well, there's nothing like CONFIG_GENERICARCH on x86_64 or I'm obviously > missing something. :-) > > On x86_64 I can choose between X86_PC and X86_VSMP and I'm not sure I'd like > to set X86_VSMP just in order to be able to suspend a box with a dual-core CPU. > IMHO that would be over the top. > This change is only for i386.. check the patch, its introduced only for arch/i386/Kconfig There is no change to x86_64, we anyway choose physflat mode in x86_64 which is exactly same as bigsmp in i386. We didnt change anything in x86_64...Why this speculation :( Iam attaching that patch for your reference here... in case you lost it and looking at some other patch. :-) Could you _please_ really check this and tell me if there is real concern... its pretty simple patch... no other arch is affected... This patch makes CONFIG_HOTPLUG_CPU depend on !X86_PC, so we need to turn on either CONFIG_GENERICARCH, CONFIG_BIGSMP or any other subarch except X86_PC With 2.6.15+ kernels when CONFIG_HOTPLUG_CPU is turned on we switch to bigsmp mode for sending IPI's and ioapic configurations that caused the following error message. >> More than 8 CPUs detected and CONFIG_X86_PC cannot handle it. >> Use CONFIG_X86_GENERICARCH or CONFIG_X86_BIGSMP. Originally bigsmp was added just to handle >8 cpus, but now with hotplug cpu support we need to use bigsmp mode (why? see below), that cause the above error message even if there were less than 8 cpus in the system. The message is bogus, but we are cannot use logical flat mode due to issues with broadcast IPI can confuse a CPU just comming up. We use flat physical mode just like x86_64 case. More details on why bigsmp now uses flat physical mode (vs. cluster mode) in following link. http://marc.theaimsgroup.com/?l=linux-kernel&m=113261865814107&w=2 Signed-off-by: Ashok Raj --------------------------------------------------------- arch/i386/Kconfig | 2 +- 1 files changed, 1 insertion(+), 1 deletion(-) Index: linux-2.6.16-rc6-mm1/arch/i386/Kconfig =================================================================== --- linux-2.6.16-rc6-mm1.orig/arch/i386/Kconfig +++ linux-2.6.16-rc6-mm1/arch/i386/Kconfig @@ -760,7 +760,7 @@ config PHYSICAL_START config HOTPLUG_CPU bool "Support for hot-pluggable CPUs (EXPERIMENTAL)" - depends on SMP && HOTPLUG && EXPERIMENTAL && !X86_VOYAGER + depends on SMP && HOTPLUG && EXPERIMENTAL && !X86_VOYAGER && !X86_PC ---help--- Say Y here to experiment with turning CPUs off and on. CPUs can be controlled through /sys/devices/system/cpu. - 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/