From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Kiszka Subject: Re: [PATCH] cpu hotplug issue Date: Thu, 04 Aug 2011 10:40:01 +0200 Message-ID: <4E3A5AE1.9060706@siemens.com> References: <4E3193B9.5040407@siemens.com> <4E37D053.1050106@siemens.com> <20110803100702.GC19574@dhcp-192-168-178-175.profitbricks.localdomain> <4E3924D9.7000302@siemens.com> <20110803103847.GD4404@redhat.com> <4E392603.5010102@siemens.com> <20110803162507.GA21463@dhcp-192-168-178-175.profitbricks.localdomain> <20110804080156.GE4404@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Vasilis Liaskovitis , "seabios@seabios.org" , "kvm@vger.kernel.org" , "armbru@redhat.com" To: Gleb Natapov Return-path: Received: from thoth.sbs.de ([192.35.17.2]:16662 "EHLO thoth.sbs.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750984Ab1HDIkM (ORCPT ); Thu, 4 Aug 2011 04:40:12 -0400 In-Reply-To: <20110804080156.GE4404@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On 2011-08-04 10:01, Gleb Natapov wrote: > On Wed, Aug 03, 2011 at 06:25:07PM +0200, Vasilis Liaskovitis wrote: >> On Wed, Aug 03, 2011 at 12:42:11PM +0200, Jan Kiszka wrote: >>>>> Why can't Seabios read to true number online CPUs from the PIIX4 device? >>>>> The information is there already, no need for addition PV here. >>>>> >>>> Where is it in PIIX4 device? >>> >>> PROC registers (or however they are called). >> >> In qemu-kvm, the cpus_sts bitmap array in PIIX4PMState/ACPIGPE has the true >> number of online CPUS. This is accessed from the DSDT hotplug method in Seabios >> as "OperationRegion SystemIO" with address 0xaf00. Is this i/o address in the >> piix4 spec? How can it be accessed from the rest of SeaBIOS? It seems to reside >> in ACPI_PM space. >> > 0xaf00 is not part of PIIX4. PIIX4 supports nor cpu host plug > neither pci hot plug. I haven't found any PROC register in PIIX4 spec > so far. So it is some "board" extension that is declared to BIOS/OS via ACPI? In any case, the channel we need to read the number of online CPUs already exists. Jan -- Siemens AG, Corporate Technology, CT T DE IT 1 Corporate Competence Center Embedded Linux