Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964810AbWCMWZA (ORCPT ); Mon, 13 Mar 2006 17:25:00 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S964812AbWCMWZA (ORCPT ); Mon, 13 Mar 2006 17:25:00 -0500 Received: from smtp.osdl.org ([65.172.181.4]:50835 "EHLO smtp.osdl.org") by vger.kernel.org with ESMTP id S964810AbWCMWY6 (ORCPT ); Mon, 13 Mar 2006 17:24:58 -0500 Date: Mon, 13 Mar 2006 14:22:23 -0800 From: Andrew Morton To: Ashok Raj Cc: ashok.raj@intel.com, olel@ans.pl, venkatesh.pallipadi@intel.com, linux-kernel@vger.kernel.org, suresh.b.siddha@intel.com, rajesh.shah@intel.com, ak@muc.de Subject: Re: More than 8 CPUs detected and CONFIG_X86_PC cannot handle it on 2.6.16-rc6 Message-Id: <20060313142223.7ac20a65.akpm@osdl.org> In-Reply-To: <20060313120552.A25020@unix-os.sc.intel.com> References: <20060311210353.7eccb6ed.akpm@osdl.org> <20060312032523.109361c1.akpm@osdl.org> <20060312073524.A9213@unix-os.sc.intel.com> <20060312143053.530ef6c9.akpm@osdl.org> <20060313113615.A24797@unix-os.sc.intel.com> <20060313115155.24dfb6f3.akpm@osdl.org> <20060313120552.A25020@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: 2314 Lines: 56 Ashok Raj wrote: > > > > When CONFIG_HOTPLUG_CPU is turned on we always use physflat mode (bigsmp) even > when #of CPUs are less than 8 to avoid sending IPI to offline processors. > > Without having BIGSMP on it spits out a warning during boot on systems that > seems misleading, since it complains even on systems that have less > than 8 cpus. > > 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. Still seems wrong. People _do_ use HOTPLUG_CPU on X86_PCs so they can get software suspend. The number of people who do this are probably 100000x the number of people who have physically hotpluggable CPUs. And I don't think we can churn their config requirements this much so late in the game. So for now I suggest we're best off simply killing the printk (or doing something smarter, like comparing cpu_online-map with cpu_possible_map (which isn't right)). Longer term, it appears that we need to do some Kconfig and C work to separate out the HOTPLUG_CPU infrastructure which swsusp needs from actual CPU hotplugging. What _is_ this IPI problem anyway? Can't send point-to-point IPIs to offlined CPUs? (Don't do that then?) Or do broadcast IPIs go wrong, or what? And does it affect pretend-x86-hotplug, or is it only affecting real hotplug? Thanks. - 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/