From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932138AbWKMR5z (ORCPT ); Mon, 13 Nov 2006 12:57:55 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753511AbWKMR5z (ORCPT ); Mon, 13 Nov 2006 12:57:55 -0500 Received: from mga05.intel.com ([192.55.52.89]:63813 "EHLO fmsmga101.fm.intel.com") by vger.kernel.org with ESMTP id S1753379AbWKMR5y (ORCPT ); Mon, 13 Nov 2006 12:57:54 -0500 X-ExtLoop1: 1 X-IronPort-AV: i="4.09,418,1157353200"; d="scan'208"; a="15227549:sNHT32821290" Date: Mon, 13 Nov 2006 09:34:47 -0800 From: "Siddha, Suresh B" To: Ingo Molnar Cc: "Siddha, Suresh B" , Andi Kleen , Andrew Morton , linux-kernel@vger.kernel.org, ashok.raj@intel.com Subject: Re: [patch] genapic: optimize & fix APIC mode setup Message-ID: <20061113093447.B17720@unix-os.sc.intel.com> References: <20061111151414.GA32507@elte.hu> <200611111620.24551.ak@suse.de> <20061112175050.A17720@unix-os.sc.intel.com> <20061113084315.GB25604@elte.hu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5.1i In-Reply-To: <20061113084315.GB25604@elte.hu>; from mingo@elte.hu on Mon, Nov 13, 2006 at 09:43:16AM +0100 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Nov 13, 2006 at 09:43:16AM +0100, Ingo Molnar wrote: > > * Siddha, Suresh B wrote: > > > There is an issue of using clustered mode along with cpu hotplug. More > > details are at the below link. > > > > http://marc.theaimsgroup.com/?l=linux-kernel&m=113261865814107&w=2 > > ok, to make sure i understand this right: it is not safe to switch any > local APIC in the system into clustered APIC mode on the E850x chipset > /at all/, because if one of the CPUs gets an INIT/startup IPI message > its local APIC will default to logical flat mode and might confuse the > chipset? "at all" is not quite correct. We are fine as long as all the cpus are up in clustered APIC mode before the IO-APIC RTE's are programmed. Once the IO-APIC subsystem is up and running and later if the cpu comes online then we have a window between the INIT/startup IPI message and the place where we program the DFR and LDR, with in which the IO-APIC will interpret the logical mode in RTE as 'logical flat' and will probably result in missing the interrupt. thanks, suresh > > on large systems that have their APIC IDs set up to group CPUs amongst > different clusters and hence triggered cluster mode, the chipset does > not get confused by this, correct? > > Ingo