diff --git a/sys/arch/xen/conf/GENERIC b/sys/arch/xen/conf/GENERIC
index f67e9125ef2c..07e67fc2c8d9 100644
--- a/sys/arch/xen/conf/GENERIC
+++ b/sys/arch/xen/conf/GENERIC
@@ -1,4 +1,4 @@
-# $NetBSD: GENERIC,v 1.15 2004/09/04 23:29:57 manu Exp $
+# $NetBSD: GENERIC,v 1.16 2004/09/23 02:24:22 tls Exp $
 # NetBSD: GENERIC,v 1.596 2004/04/07 13:13:59 augustss Exp 
 #
 # GENERIC machine description file
@@ -23,14 +23,13 @@ include 	"arch/xen/conf/std.xen"
 
 options 	INCLUDE_CONFIG_FILE	# embed config file in kernel binary
 
-#ident 		"GENERIC-$Revision: 1.15 $"
+#ident 		"GENERIC-$Revision: 1.16 $"
 
 maxusers	32		# estimated number of users
 
 #
 options		XEN
 options		DOM0OPS
-options		HZ=50
 
 # CPU support.  At least one is REQUIRED.
 options 	I686_CPU
@@ -55,7 +54,7 @@ options 	I686_CPU
 options 	INSECURE	# disable kernel security levels - X needs this
 
 options 	RTC_OFFSET=0	# hardware clock is this many mins. west of GMT
-#options 	NTP		# NTP phase/frequency locked loop
+options 	NTP		# NTP phase/frequency locked loop
 #options 	NO_TSC_TIME	# Don't use TSC microtime, even if available.
 				# Improves time behavior under VMware.
 
diff --git a/sys/arch/xen/conf/XEN b/sys/arch/xen/conf/XEN
index b1a996309f50..2405bdc78be3 100644
--- a/sys/arch/xen/conf/XEN
+++ b/sys/arch/xen/conf/XEN
@@ -1,4 +1,4 @@
-# $NetBSD: XEN,v 1.12 2004/09/04 23:29:57 manu Exp $
+# $NetBSD: XEN,v 1.13 2004/09/23 02:24:22 tls Exp $
 
 include 	"arch/xen/conf/std.xen"
 
@@ -13,7 +13,6 @@ maxusers	32		# estimated number of users
 #
 options		XEN
 options		DOM0OPS
-options		HZ=50
 
 #options 	I586_CPU
 options 	I686_CPU
@@ -29,7 +28,7 @@ options 	I686_CPU
 options		INSECURE	# disable kernel security levels - X needs this
 
 options 	RTC_OFFSET=0	# hardware clock is this many mins. west of GMT
-#options 	NTP		# NTP phase/frequency locked loop
+options 	NTP		# NTP phase/frequency locked loop
 
 options 	KTRACE		# system call tracing via ktrace(1)
 #options 	SYSTRACE	# system call vetting via systrace(1)
diff --git a/sys/arch/xen/i386/locore.S b/sys/arch/xen/i386/locore.S
index 78153d76eb3b..a3bb95182c5e 100644
--- a/sys/arch/xen/i386/locore.S
+++ b/sys/arch/xen/i386/locore.S
@@ -1,4 +1,4 @@
-/*	$NetBSD: locore.S,v 1.5 2004/04/26 22:05:04 cl Exp $	*/
+/*	$NetBSD: locore.S,v 1.6 2004/09/23 02:24:22 tls Exp $	*/
 /*	NetBSD: locore.S,v 1.26 2004/04/12 13:17:46 yamt Exp 	*/
 
 /*-
@@ -1588,6 +1588,7 @@ idle_zero:
 	pushl	$IPL_NONE
 	call	_C_LABEL(Xspllower)
 	addl	$4,%esp
+	jmp	idle_start
 4:
 	call	_C_LABEL(uvm_pageidlezero)
 	CLI(%eax)
diff --git a/sys/arch/xen/xen/clock.c b/sys/arch/xen/xen/clock.c
index 72c90af2bdfc..ca762e9d4469 100644
--- a/sys/arch/xen/xen/clock.c
+++ b/sys/arch/xen/xen/clock.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: clock.c,v 1.6 2004/07/16 22:36:33 tls Exp $	*/
+/*	$NetBSD: clock.c,v 1.7 2004/09/23 02:24:22 tls Exp $	*/
 
 /*
  *
@@ -34,7 +34,7 @@
 #include "opt_xen.h"
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: clock.c,v 1.6 2004/07/16 22:36:33 tls Exp $");
+__KERNEL_RCSID(0, "$NetBSD: clock.c,v 1.7 2004/09/23 02:24:22 tls Exp $");
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -54,13 +54,17 @@ __KERNEL_RCSID(0, "$NetBSD: clock.c,v 1.6 2004/07/16 22:36:33 tls Exp $");
 static int xen_timer_handler(void *, struct trapframe *);
 
 /* These are peridically updated in shared_info, and then copied here. */
-static unsigned long shadow_tsc_stamp;
-static u_int64_t shadow_system_time;
+static uint64_t shadow_tsc_stamp;
+static uint64_t shadow_system_time;
 static unsigned long shadow_time_version;
 static struct timeval shadow_tv;
 
 static int timeset;
 
+static uint64_t processed_system_time;
+
+#define NS_PER_TICK (1000000000ULL/hz)
+
 /*
  * Reads a consistent set of time-base values from Xen, into a shadow data
  * area.  Must be called at splclock.
@@ -73,12 +77,23 @@ get_time_values_from_xen(void)
 		__insn_barrier();
 		shadow_tv.tv_sec = HYPERVISOR_shared_info->wc_sec;
 		shadow_tv.tv_usec = HYPERVISOR_shared_info->wc_usec;
-		shadow_tsc_stamp = HYPERVISOR_shared_info->tsc_timestamp;
+		shadow_tsc_stamp = HYPERVISOR_shared_info->tsc_timestamp <<
+		    HYPERVISOR_shared_info->rdtsc_bitshift;
 		shadow_system_time = HYPERVISOR_shared_info->system_time;
 		__insn_barrier();
 	} while (shadow_time_version != HYPERVISOR_shared_info->time_version1);
 }
 
+static uint64_t
+get_tsc_offset_ns(void)
+{
+	uint32_t tsc_delta;
+	struct cpu_info *ci = curcpu();
+
+	tsc_delta = cpu_counter32() - shadow_tsc_stamp;
+	return tsc_delta * 1000000000 / cpu_frequency(ci);
+}
+
 void
 inittodr(time_t base)
 {
@@ -189,6 +204,9 @@ void
 xen_initclocks()
 {
 
+	get_time_values_from_xen();
+	processed_system_time = shadow_system_time;
+	
 	event_set_handler(_EVENT_TIMER, (int (*)(void *))xen_timer_handler,
 	    NULL, IPL_CLOCK);
 	hypervisor_enable_event(_EVENT_TIMER);
@@ -197,6 +215,8 @@ xen_initclocks()
 static int
 xen_timer_handler(void *arg, struct trapframe *regs)
 {
+	int64_t delta;
+
 #if defined(I586_CPU) || defined(I686_CPU)
 	static int microset_iter; /* call cc_microset once/sec */
 	struct cpu_info *ci = curcpu();
@@ -222,7 +242,13 @@ xen_timer_handler(void *arg, struct trapframe *regs)
 
 	get_time_values_from_xen();
 
-	hardclock((struct clockframe *)regs);
+	delta = (int64_t)(shadow_system_time + get_tsc_offset_ns() -
+			  processed_system_time);
+	while (delta >= NS_PER_TICK) {
+		hardclock((struct clockframe *)regs);
+		delta -= NS_PER_TICK;
+		processed_system_time += NS_PER_TICK;
+	}
 
 	return 0;
 }