From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753226AbcGUPGO (ORCPT ); Thu, 21 Jul 2016 11:06:14 -0400 Received: from foss.arm.com ([217.140.101.70]:48671 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753044AbcGUPGB (ORCPT ); Thu, 21 Jul 2016 11:06:01 -0400 Date: Thu, 21 Jul 2016 16:05:56 +0100 From: Catalin Marinas To: Suzuki K Poulose Cc: Mark Rutland , will.deacon@arm.com, linux-kernel@vger.kernel.org, James Morse , linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH] [4.7] arm64: Honor nosmp kernel command line option Message-ID: <20160721150556.GE16666@e104818-lin.cambridge.arm.com> References: <1469096127-1136-1-git-send-email-suzuki.poulose@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1469096127-1136-1-git-send-email-suzuki.poulose@arm.com> 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 On Thu, Jul 21, 2016 at 11:15:27AM +0100, Suzuki K. Poulose wrote: > Passing "nosmp" should boot the kernel with a single processor, without > provision to enable secondary CPUs even if they are present. "nosmp" is > implemented by setting maxcpus=0. At the moment we still mark the secondary > CPUs present even with nosmp, which allows the userspace to bring them > up. This patch corrects the smp_prepare_cpus() to honor the maxcpus == 0. > > Commit 44dbcc93ab67145 ("arm64: Fix behavior of maxcpus=N") fixed the > behavior for maxcpus >= 1, but broke maxcpus = 0. > > Fixes: commit 44dbcc93ab67145 ("arm64: Fix behavior of maxcpus=N") > Cc: Will Deacon > Cc: Catalin Marinas > Cc: Mark Rutland > Cc: James Morse > Signed-off-by: Suzuki K Poulose Queued for 4.8, with Mark's comment and a cc stable for 4.7 -- Catalin