Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755850Ab3F1QJT (ORCPT ); Fri, 28 Jun 2013 12:09:19 -0400 Received: from www.linutronix.de ([62.245.132.108]:46972 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754521Ab3F1QJR (ORCPT ); Fri, 28 Jun 2013 12:09:17 -0400 Date: Fri, 28 Jun 2013 18:09:15 +0200 (CEST) From: Thomas Gleixner To: David Vrabel cc: xen-devel@lists.xen.org, Konrad Rzeszutek Wilk , linux-kernel@vger.kernel.org, John Stultz Subject: Re: [PATCH 5/5] x86/xen: sync the CMOS RTC as well as the Xen wallclock In-Reply-To: <51CDB0A1.6080409@citrix.com> Message-ID: References: <1372329348-20841-1-git-send-email-david.vrabel@citrix.com> <1372329348-20841-6-git-send-email-david.vrabel@citrix.com> <51CDB0A1.6080409@citrix.com> User-Agent: Alpine 2.02 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1373 Lines: 40 On Fri, 28 Jun 2013, David Vrabel wrote: > > Before: > > Xen wallclock set when time is stepped. > Xen wallclock set every 11 minutes (by sync_cmos_clock()). > Hardware RTC never set. > > After: > > Xen wallclock set when time is stepped. > Xen wallclock set every 11 minutes (in pvclock gtod notifier). Ah, you are emulating the sync_cmos_clock() behaviour for the xen wallclock via the periodic pvclock_gtod notifier call. > Hardware RTC set every 11 minutes (by sync_cmos_clock()). > > I'll update the changelog to be more descriptive: > > Adjustments to Xen's persistent clock via update_persistent_clock() > don't actually persist, as the Xen wallclock is a software only clock > and modifications to it do not modify the underlying CMOS RTC. > > The x86_platform.set_wallclock hook can be used to keep the hardware > RTC synchronized (as on bare metal). If (in dom0) we make the Xen > wallclock periodically synchronized by the pvclock_gtod notifier, the > set_wallclock hook need not update the Xen wallclock and the native > implementation can be used. Yep. I'll pick that up. Thanks, tglx -- 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/