From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751929AbeCUJIr (ORCPT ); Wed, 21 Mar 2018 05:08:47 -0400 Received: from merlin.infradead.org ([205.233.59.134]:44634 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751879AbeCUJIp (ORCPT ); Wed, 21 Mar 2018 05:08:45 -0400 Date: Wed, 21 Mar 2018 10:08:26 +0100 From: Peter Zijlstra To: Dou Liyang Cc: linux-kernel@vger.kernel.org, x86@kernel.org, linux-acpi@vger.kernel.org, linux-doc@vger.kernel.org, tglx@linutronix.de, mingo@redhat.com, corbet@lwn.net, rjw@rjwysocki.net, lenb@kernel.org, hpa@zytor.com Subject: Re: [PATCH 1/5] x86/smpboot: Add the missing description of possible_cpus Message-ID: <20180321090826.GW4043@hirez.programming.kicks-ass.net> References: <20180320110432.28127-1-douly.fnst@cn.fujitsu.com> <20180320110432.28127-2-douly.fnst@cn.fujitsu.com> <20180320123712.GR4043@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.3 (2018-01-21) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Mar 21, 2018 at 01:33:24PM +0800, Dou Liyang wrote: > How about: > > possible_cpus= [s390,x86_64] Set the number of possible CPUs which > are determined by the ACPI tables MADT or mptables by > default. possible_cpus=n : n >= 1 enforces the possible > number to be 'n'. > While nr_cpus is also be set: nr_cpus=m, choice the > minimum one for the number of possible CPUs. So what is the exact difference between possible_cpus and nr_cpus ? I konw maxcpus= limits the number of CPUs we bring up, and possible_cpus limits the possible_map, but I'm not entirely sure what nr_cpus does here.