From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933615Ab2AKRYh (ORCPT ); Wed, 11 Jan 2012 12:24:37 -0500 Received: from mga01.intel.com ([192.55.52.88]:9550 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757195Ab2AKRYe (ORCPT ); Wed, 11 Jan 2012 12:24:34 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.71,315,1320652800"; d="scan'208";a="106055445" From: "Fenghua Yu" To: "Ingo Molnar" , "Thomas Gleixner" , "H Peter Anvin" , "Linus Torvalds" , "Andrew Morton" , "Asit K Mallick" , "Tony Luck" , "Arjan van de Ven" , "Suresh B Siddha" , "Len Brown" , "Randy Dunlap" , "Srivatsa S. Bhat" , Konrad Rzeszutek Wilk , Peter Zijlstra , "Chen Gong" , "linux-kernel" , "linux-pm" , "x86" Cc: Fenghua Yu Subject: [PATCH v5 02/12] x86/Kconfig: Add config switch for CPU0 hotplug Date: Wed, 11 Jan 2012 09:04:43 -0800 Message-Id: <1326301493-28760-3-git-send-email-fenghua.yu@intel.com> X-Mailer: git-send-email 1.7.2 In-Reply-To: <1326301493-28760-1-git-send-email-fenghua.yu@intel.com> References: <1326301493-28760-1-git-send-email-fenghua.yu@intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Fenghua Yu New config switch CONFIG_BOOTPARAM_HOTPLUG_CPU0 sets default state of whether the CPU0 hotplug is on or off. If the switch is off, CPU0 is not hotpluggable by default. But the CPU0 hotplug feature can still be turned on by kernel parameter cpu0_hotplug at boot. If the switch is on, CPU0 is always hotpluggable. The default value of the switch is off. Signed-off-by: Fenghua Yu --- arch/x86/Kconfig | 29 +++++++++++++++++++++++++++++ 1 files changed, 29 insertions(+), 0 deletions(-) diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index d6f1e91..c2cf195 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -1719,6 +1719,35 @@ config HOTPLUG_CPU automatically on SMP systems. ) Say N if you want to disable CPU hotplug. +config BOOTPARAM_HOTPLUG_CPU0 + bool "Set default setting of cpu0_hotpluggable" + default n + depends on HOTPLUG_CPU && EXPERIMENTAL + ---help--- + Set whether default state of cpu0_hotpluggable is on or off. + + Say Y here to enable CPU0 hotplug by default. If this switch + is turned on, there is no need to give cpu0_hotplug kernel + parameter and the CPU0 hotplug feature is enabled by default. + + Please note: there are two known CPU0 dependencies if you want + to enable the CPU0 hotplug feature either by this switch or by + cpu0_hotplug kernel parameter. + + First, resume from hibernate or suspend always starts from CPU0. + So hibernate and suspend are prevented if CPU0 is offline. + + Second dependency is PIC interrupts always go to CPU0. CPU0 can not + offline if any interrupt can not migrate out of CPU0. There may + be other CPU0 dependencies. + + Please make sure the dependencies are under your control before + you enable this feature. + + Say N if you don't want to enable CPU0 hotplug feature by default. + You still can enable the CPU0 hotplug feature at boot by kernel + parameter cpu0_hotplug. + config COMPAT_VDSO def_bool y prompt "Compat VDSO support" -- 1.6.0.3