From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1422688AbXDCUS7 (ORCPT ); Tue, 3 Apr 2007 16:18:59 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1945898AbXDCUS7 (ORCPT ); Tue, 3 Apr 2007 16:18:59 -0400 Received: from sceptre.pobox.com ([207.106.133.20]:51651 "EHLO sceptre.pobox.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1422688AbXDCUS6 (ORCPT ); Tue, 3 Apr 2007 16:18:58 -0400 Date: Tue, 3 Apr 2007 15:20:38 -0500 From: Nathan Lynch To: Ulrich Drepper Cc: "Siddha, Suresh B" , Linux Kernel , Andrew Morton Subject: Re: getting processor numbers Message-ID: <20070403202038.GR8423@localdomain> References: <461286D6.2040407@redhat.com> <46128C1B.1090900@redhat.com> <20070403172736.GA23689@one.firstfloor.org> <46128F47.2010107@redhat.com> <20070403174457.GA15704@linux-os.sc.intel.com> <4612B12A.30609@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4612B12A.30609@redhat.com> User-Agent: Mutt/1.5.12-2006-07-14 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Ulrich Drepper wrote: > Siddha, Suresh B wrote:a > > Not all of the cpu* directories in /sys/devices/system/cpu may be > > online. > > Apparently this information isn't needed. It's very easy to verify: > > $ ls /sys/devices/system/cpu/*/online > /sys/devices/system/cpu/cpu1/online /sys/devices/system/cpu/cpu2/online > /sys/devices/system/cpu/cpu3/online > > This is a quad core machine and cpu0 doesn't have the 'online' file > (2.6.19 kernel). So, if nobody noticed this it's not needed and we can > just remove CPUs from /sys/devices/system/cpu when they are brought > offline, right? No... the online sysfs files are used to show and change cpus' online/offline state. You wouldn't be able to bring an offlined cpu back online again. cpu0 doesn't have an online file on machines which don't support offlining of the boot cpu.