From: David Vrabel <david.vra...@citrix.com>
Adjustments to Xen's persistent_clock via update_persistent_clock()
don't actually persist, as the Xen wallclock is just used by domU
guests, 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). Because the Xen wallclock is now
kept synchronized by xen_pvclock_gtod_notify() on any system time
change, xen_set_wallclock() need not do this and dom0 can simply use
the native implementation.
Signed-off-by: David Vrabel <david.vra...@citrix.com>
---
arch/x86/xen/time.c | 17 ++++-------------
1 files changed, 4 insertions(+), 13 deletions(-)
diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c
index 60b7d1f..0e69994 100644
--- a/arch/x86/xen/time.c
+++ b/arch/x86/xen/time.c
@@ -199,18 +199,7 @@ static void xen_get_wallclock(struct timespec *now)
static int xen_set_wallclock(const struct timespec *now)
{
- struct xen_platform_op op;
-
- /* do nothing for domU */
- if (!xen_initial_domain())
- return -1;
-
- 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);
+ return -1;
}
static int xen_pvclock_gtod_notify(struct notifier_block *nb, unsigned long
unused,
@@ -531,7 +520,9 @@ void __init xen_init_time_ops(void)
x86_platform.calibrate_tsc = xen_tsc_khz;
x86_platform.get_wallclock = xen_get_wallclock;
- x86_platform.set_wallclock = xen_set_wallclock;
+ /* Dom0 uses the native method to set the hardware RTC. */
+ if (!xen_initial_domain())
+ x86_platform.set_wallclock = xen_set_wallclock;
}
#ifdef CONFIG_XEN_PVHVM
--
1.7.2.5
--
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