From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755291Ab3KKTyY (ORCPT ); Mon, 11 Nov 2013 14:54:24 -0500 Received: from terminus.zytor.com ([198.137.202.10]:48054 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754081Ab3KKTyS (ORCPT ); Mon, 11 Nov 2013 14:54:18 -0500 Message-ID: <528135D8.3040205@zytor.com> Date: Mon, 11 Nov 2013 11:54:00 -0800 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.1.0 MIME-Version: 1.0 To: Ingo Molnar CC: linux-kernel@vger.kernel.org, tglx@linutronix.de, d.hatayama@jp.fujitsu.com, hpa@linux.intel.com, linux-tip-commits@vger.kernel.org Subject: Re: [tip:x86/bsp-hotplug] x86, apic: Disable BSP if boot cpu is AP References: <20130829092804.5476.95588.stgit@localhost6.localdomain6> <52598770.6090309@zytor.com> <20131012174206.GD18437@gmail.com> In-Reply-To: <20131012174206.GD18437@gmail.com> X-Enigmail-Version: 1.6 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 10/12/2013 10:42 AM, Ingo Molnar wrote: > > * H. Peter Anvin wrote: > >> On 10/09/2013 04:16 PM, tip-bot for HATAYAMA Daisuke wrote: >>> Commit-ID: 1d79e607332d67d9132c176d99b5e7fabe1b6b7f >>> Gitweb: http://git.kernel.org/tip/1d79e607332d67d9132c176d99b5e7fabe1b6b7f >>> Author: HATAYAMA Daisuke >>> AuthorDate: Thu, 29 Aug 2013 18:28:04 +0900 >>> Committer: H. Peter Anvin >>> CommitDate: Wed, 9 Oct 2013 15:41:11 -0700 >>> >>> x86, apic: Disable BSP if boot cpu is AP >> >> This patch seems to trigger build failures in some configurations. >> Specifically: >> >> (.init.text+0x1307): undefined reference to `boot_cpu_is_bsp_init' >> >> Unfortunately I don't have the specific configuration which triggers the >> failure, as this was discovered by Fengguang's robot. > > I have triggered that too and have such a config, it's attached. Okay, thinking about this again, this patchset is in fact broken on: 1. Any configuration which has CONFIG_SMP=n and CONFIG_X86_UP_APIC=n. This is a built-time problem. 2. Any CPU which is old enough that MSR_IA32_APICBASE doesn't exist. This is a fatal runtime bug. 3. Any clustered solution which involves a third-party cluster controller such that MSR_IA32_APICBASE may not reflect the reality of the system. This is a less critical issue as "all" it ought to make happen is to disable some CPUs which didn't need it. Hatayama-san, you got this build bug report almost a month ago. It looks like it is going to need a fair bit of cleanup, so I fear this is going to be dropped for v3.13. -hpa