From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932088AbXGTB1R (ORCPT ); Thu, 19 Jul 2007 21:27:17 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1760856AbXGTB1H (ORCPT ); Thu, 19 Jul 2007 21:27:07 -0400 Received: from smtp-outbound-1.vmware.com ([65.113.40.141]:45644 "EHLO smtp-outbound-1.vmware.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761012AbXGTB1E (ORCPT ); Thu, 19 Jul 2007 21:27:04 -0400 Message-ID: <46A00CC2.6010407@vmware.com> Date: Thu, 19 Jul 2007 18:15:46 -0700 From: Zachary Amsden User-Agent: Thunderbird 1.5.0.12 (X11/20070509) MIME-Version: 1.0 To: Mathieu Desnoyers CC: Andi Kleen , jbeulich@novell.com, "S. P. Prasanna" , linux-kernel@vger.kernel.org, patches@x86-64.org, Jeremy Fitzhardinge Subject: Re: new text patching for review References: <200707191105.44056.ak@suse.de> <20070719133852.GA5490@Krystal> <200707191546.08919.ak@suse.de> <20070719173502.GB12955@Krystal> <20070719234912.GB30383@Krystal> In-Reply-To: <20070719234912.GB30383@Krystal> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Mathieu Desnoyers wrote: > Yes, kprobes is case 1: atomic update. And we don't even have to bother > about Intel's erratum. This one is ok. That's mainly the > alternatives/paravirt code I worry about. > Paravirt and alternatives should all be ok because they are done before SMP bringup and with NMIs disabled. NMI watchdog is not setup until smp_prepare_cpus/check_nmi_watchdog, which happens way later, not during parse_args/setup_nmi_watchdog, which just decides which type of watchdog to setup. I originally considered the NMI problem for paravirt-ops patching done during module load, and found that I would need to modify stop_machine_run to have an architecture specific callout to mask and unmask NMIs. I didn't imagine that would be very popular, and VMI was the only paravirt-ops that were considering module load time patching, so I flushed it. You get some other nasty issues as well with run-time switching, like missing early init calls (in particular, we would have to go to some heroics to retake the land surrounding the APIC local timer interrupt). Zach