From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757183Ab3EOITt (ORCPT ); Wed, 15 May 2013 04:19:49 -0400 Received: from nat28.tlf.novell.com ([130.57.49.28]:41889 "EHLO nat28.tlf.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756011Ab3EOITr convert rfc822-to-8bit (ORCPT ); Wed, 15 May 2013 04:19:47 -0400 Message-Id: <5193613E02000078000D64E9@nat28.tlf.novell.com> X-Mailer: Novell GroupWise Internet Agent 12.0.2 Date: Wed, 15 May 2013 09:19:42 +0100 From: "Jan Beulich" To: "David Vrabel" , "John Stultz" Cc: "Thomas Gleixner" , , "Konrad Rzeszutek Wilk" , Subject: Re: [Xen-devel] [PATCH 3/3] x86/xen: sync the CMOS RTC as well as the Xen wallclock References: <1368467768-2316-1-git-send-email-david.vrabel@citrix.com> <1368467768-2316-4-git-send-email-david.vrabel@citrix.com> <51927339.5070402@linaro.org> In-Reply-To: <51927339.5070402@linaro.org> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 8BIT Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org >>> On 14.05.13 at 19:24, John Stultz wrote: > On 05/13/2013 10:56 AM, David Vrabel wrote: >> From: David Vrabel >> >> If NTP is used in dom0 and it is synchronized to its clock source, >> then the kernel will periodically synchronize the Xen wallclock with >> the system time. Updates to the Xen wallclock do not persist across >> reboots, so also synchronize the CMOS RTC (as on bare metal). >> >> Signed-off-by: David Vrabel >> --- >> arch/x86/xen/time.c | 11 ++++++++++- >> 1 files changed, 10 insertions(+), 1 deletions(-) >> >> diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c >> index a1947ac..4656165 100644 >> --- a/arch/x86/xen/time.c >> +++ b/arch/x86/xen/time.c >> @@ -14,6 +14,7 @@ >> #include >> #include >> #include >> +#include >> >> #include >> #include >> @@ -199,17 +200,25 @@ static void xen_get_wallclock(struct timespec *now) >> static int xen_set_wallclock(const struct timespec *now) >> { >> struct xen_platform_op op; >> + int ret; >> >> /* do nothing for domU */ >> if (!xen_initial_domain()) >> return -1; >> >> + /* Set the Xen wallclock. */ >> op.cmd = XENPF_settime; >> op.u.settime.secs = now->tv_sec; >> op.u.settime.nsecs = now->tv_nsec; >> op.u.settime.system_time = xen_clocksource_read(); >> >> - return HYPERVISOR_dom0_op(&op); >> + ret = HYPERVISOR_dom0_op(&op); >> + if (ret) >> + return ret; >> + >> + /* Set the hardware RTC. */ >> + return mach_set_rtc_mmss(now); > > Sorry, just noticed one more thing while applying this. Do all Xen > systems run on hardware that has the conventional CMOS clock? > > What happens if the bare-metal needs to use efi_set_rtc() or > vrtc_set_mmss() ? There's no EFI support in the upstream kernel yet when running on Xen (the code that's in the kernel can't be used, as Dom0 can't directly invoke EFI runtime service functions). And I don't think Xen is in any way prepared to run on Moorestown, which afaict is where vrtc_set_mmss() comes into the picture. Jan