Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758338Ab2BJPp7 (ORCPT ); Fri, 10 Feb 2012 10:45:59 -0500 Received: from rcsinet15.oracle.com ([148.87.113.117]:34956 "EHLO rcsinet15.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758133Ab2BJPp5 (ORCPT ); Fri, 10 Feb 2012 10:45:57 -0500 Date: Fri, 10 Feb 2012 10:42:55 -0500 From: Konrad Rzeszutek Wilk To: Ian Campbell Cc: "linux-kernel@vger.kernel.org" , "xen-devel@lists.xensource.com" , gregkh@linuxfoundation.org Subject: Re: [Xen-devel] [PATCH] xen/cpu: Make VCPU hotplug code online CPUs properly. Message-ID: <20120210154255.GA9857@phenom.dumpdata.com> References: <1328885033-8450-1-git-send-email-konrad.wilk@oracle.com> <1328885033-8450-2-git-send-email-konrad.wilk@oracle.com> <1328886226.6133.271.camel@zakaz.uk.xensource.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1328886226.6133.271.camel@zakaz.uk.xensource.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-Source-IP: ucsinet22.oracle.com [156.151.31.94] X-CT-RefId: str=0001.0A090204.4F353BB0.004C,ss=1,re=0.000,fgs=0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1216 Lines: 27 On Fri, Feb 10, 2012 at 03:03:46PM +0000, Ian Campbell wrote: > On Fri, 2012-02-10 at 14:43 +0000, Konrad Rzeszutek Wilk wrote: > > Offlining CPUs works. Onlining does not work anymore and it looks > > like we were missing a cpu_up() call in the hotplug bring up path. > > Wasn't this a deliberate decision as part of the pvops upstreaming to be > consistent with native cpu hotplug? After hotplugging a CPU Ah, hadn't seen that. Thanks for spotting that! > administrator action is needed to actually online it. > > http://xen.1045712.n5.nabble.com/cpu-down-but-no-cpu-up-in-drivers-xen-cpu-hotplug-c-td2545244.html > > The fix is to add a udev rule: > http://wiki.xen.org/wiki/Paravirt_Linux_CPU_Hotplug Ah, so I see that it is run (the udev does it) but it actually does not bring the CPU up. It looks as if the 'online' attribute is actually not present at all, even after bringing the CPU "up-but-not-online". Oh joy! Should be easy to reproduce on baremetal. -- 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/