Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751212AbWCVNIw (ORCPT ); Wed, 22 Mar 2006 08:08:52 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751170AbWCVNIw (ORCPT ); Wed, 22 Mar 2006 08:08:52 -0500 Received: from fmr21.intel.com ([143.183.121.13]:50588 "EHLO scsfmr001.sc.intel.com") by vger.kernel.org with ESMTP id S1751217AbWCVNIv (ORCPT ); Wed, 22 Mar 2006 08:08:51 -0500 Date: Wed, 22 Mar 2006 05:08:37 -0800 From: Ashok Raj To: akpm@osdl.org Cc: Peter Williams , Linus Torvalds , Linux Kernel Mailing List , ashok.raj@intel.com Subject: Re: Linux v2.6.16 Message-ID: <20060322050837.A9452@unix-os.sc.intel.com> References: <4420DF21.8060700@bigpond.net.au> <20060321223120.A4003@unix-os.sc.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5.1i In-Reply-To: <20060321223120.A4003@unix-os.sc.intel.com>; from ashok.raj@intel.com on Tue, Mar 21, 2006 at 10:31:20PM -0800 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2662 Lines: 74 On Tue, Mar 21, 2006 at 10:31:20PM -0800, Ashok Raj wrote: > On Tue, Mar 21, 2006 at 09:22:41PM -0800, Peter Williams wrote: > > > > I/O APICs > > Mar 22 16:10:31 heathwren kernel: More than 8 CPUs detected and > > CONFIG_X86_PC cannot handle it. > > > > ### No more CPUs seen but something in there thinks there's more than > > 8 > > of them. > > > > Mar 22 16:10:31 heathwren kernel: Use CONFIG_X86_GENERICARCH or > > CONFIG_X86_BIGSMP. > > > > Hi Andrew Please consider for inclusion... resending with changelog per Andrew. -- Cheers, Ashok Raj - Open Source Technology Center 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 when CONFIG_HOTPLUG_CPU=y 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/