From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755633Ab2KUSiP (ORCPT ); Wed, 21 Nov 2012 13:38:15 -0500 Received: from terminus.zytor.com ([198.137.202.10]:53534 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755567Ab2KUSiO (ORCPT ); Wed, 21 Nov 2012 13:38:14 -0500 Message-ID: <50AD1F88.1010006@zytor.com> Date: Wed, 21 Nov 2012 10:38:00 -0800 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:16.0) Gecko/20121029 Thunderbird/16.0.2 MIME-Version: 1.0 To: Sasha Levin CC: tglx@linutronix.de, mingo@redhat.com, x86@kernel.org, linux-kernel@vger.kernel.org, penberg@kernel.org Subject: Re: [PATCH] x86, smpboot: allow manual hotplug of CPUs References: <1353522136-14944-1-git-send-email-sasha.levin@oracle.com> <50AD1CB6.9030707@zytor.com> <50AD1EE7.6020304@oracle.com> In-Reply-To: <50AD1EE7.6020304@oracle.com> X-Enigmail-Version: 1.4.6 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/21/2012 10:35 AM, Sasha Levin wrote: >> >> Reading between the lines, this sounds like would cause a user-visible >> difference between mptable platforms and ACPI platforms? If so, that is >> totally unacceptable. If not, the description is confusing. > > With ACPI platforms you don't need probe/release because the hardware notifies > on CPU insert/eject - this doesn't exist on mptable which is why you have to > do it manually with probe/release. > > The difference is already user visible: you can hotplug on ACPI, but can't on > mptables. > > Yes, reading back the subject does sound confusing - a better one would probably > be "provide interface for CPU hotplug on mptable platforms" or something similar. > So, are there any mptables platforms which support hotplug? If the answer is "KVM" then the answer is that KVM needs to move to ACPI to get the proper functionality; putting a hack in is really not okay. -hpa