From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Vrabel Subject: Re: [PATCH 5/5] x86/xen: sync the CMOS RTC as well as the Xen wallclock Date: Fri, 28 Jun 2013 17:51:17 +0100 Message-ID: <51CDBF05.5070502__10018.9041732394$1372438391$gmane$org@citrix.com> 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> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Thomas Gleixner Cc: John Stultz , linux-kernel@vger.kernel.org, xen-devel@lists.xen.org List-Id: xen-devel@lists.xenproject.org On 28/06/13 17:09, Thomas Gleixner wrote: > 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. If it helps, I've made this change as well as splitting the xen part of the hrtimers patch out into a separate commit. The following changes since commit 52efa9eb9ea36b457b23b1b5d3dd9ce64d110715: x86: increase precision of x86_platform.get/set_wallclock() (2013-06-26 18:07:16 +0100) are available in the git repository at: git://xenbits.xen.org/people/dvrabel/linux.git wallclock-v8 David Vrabel (6): hrtimers: support resuming with two or more CPUs online (but stopped) time: pass flags instead of multiple bools to timekeeping_update() time: indicate that the clock was set in the pvclock gtod notifier chain xen: remove unnecessary call to clock_was_set() during resume x86/xen: sync the wallclock when the system time is set x86/xen: sync the CMOS RTC as well as the Xen wallclock arch/x86/xen/time.c | 42 +++++++++++++++++++++++++++++++++++------- drivers/xen/manage.c | 3 --- include/linux/pvclock_gtod.h | 7 +++++++ kernel/hrtimer.c | 15 ++++++++++++--- kernel/time/timekeeping.c | 39 ++++++++++++++++++++++++--------------- 5 files changed, 78 insertions(+), 28 deletions(-) David