From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753697Ab3EMR40 (ORCPT ); Mon, 13 May 2013 13:56:26 -0400 Received: from smtp.citrix.com ([66.165.176.89]:19242 "EHLO SMTP.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753321Ab3EMR4Z (ORCPT ); Mon, 13 May 2013 13:56:25 -0400 X-IronPort-AV: E=Sophos;i="4.87,663,1363132800"; d="scan'208";a="24904316" From: David Vrabel To: CC: David Vrabel , Konrad Rzeszutek Wilk , John Stultz , Thomas Gleixner , Subject: [PATCH 0/3] x86,time,xen: maintain an accurate persistent clock in more cases Date: Mon, 13 May 2013 18:56:05 +0100 Message-ID: <1368467768-2316-1-git-send-email-david.vrabel@citrix.com> X-Mailer: git-send-email 1.7.2.5 MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The kernel has limited support for updating the persistent clock or RTC when NTP is synced. This has the following limitations: * The persistent clock is not updated on step changes. This leaves a window where it will be incorrect (while NTP resyncs). * On x86, the virtual platforms have persistent clocks with nanosecond precision but this is lost in the x86_platform.set/get_wallclock() calls. Guests may see wallclocks that are out by up to 1 second. * Xen guests use the Xen wallclock as their persistent clock. dom0 maintains this clock so it is persistent for domUs and not dom0 itself. These series fixes the above limitations. Each patch in the series is independent so may be applied to their respective trees separately. David