Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754047AbbBMW7K (ORCPT ); Fri, 13 Feb 2015 17:59:10 -0500 Received: from pandora.arm.linux.org.uk ([78.32.30.218]:39879 "EHLO pandora.arm.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754018AbbBMW7G (ORCPT ); Fri, 13 Feb 2015 17:59:06 -0500 Date: Fri, 13 Feb 2015 22:58:54 +0000 From: Russell King - ARM Linux To: Magnus Damm Cc: Stephen Boyd , Simon Horman , linux-kernel , "linux-arm-kernel@lists.infradead.org" , Mark Rutland , Nicolas Pitre , Dave Martin , SH-Linux Subject: Re: [PATCH v2] ARM: smp: Only expose /sys/.../cpuX/online if hotpluggable Message-ID: <20150213225854.GG8656@n2100.arm.linux.org.uk> References: <1423850799-4028-1-git-send-email-sboyd@codeaurora.org> <20150213202002.GB29727@verge.net.au> <54DE5D3A.5070104@codeaurora.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 916 Lines: 20 On Fri, Feb 13, 2015 at 08:54:22PM +0000, Magnus Damm wrote: > Thanks for your efforts. Can you please tell me where that limitation > is located? I'm quite sure I've brought CPU cores up and down > including CPU0, but maybe something is missing? If you don't provide a cpu_disable function, by default only the non-boot (iow, non-CPU0) CPUs can be hotplugged. If you provide a cpu_disable function, it can instruct the system that fewer or more CPUs can be hotplugged, including the boot CPU. The system will then restrict you to a minimum of any one CPU online. -- FTTC broadband for 0.8mile line: currently at 10.5Mbps down 400kbps up according to speedtest.net. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/