Index: sys/amd64/conf/GENERIC
===================================================================
--- sys/amd64/conf/GENERIC
+++ sys/amd64/conf/GENERIC
@@ -380,9 +380,11 @@
 device		hyperv			# HyperV drivers 
 
 # Xen HVM Guest Optimizations
-# NOTE: XENHVM depends on xenpci.  They must be added or removed together.
+# NOTE: XENHVM depends on xenpci and xentimer.
+# They must be added or removed together.
 options 	XENHVM			# Xen HVM kernel infrastructure
 device		xenpci			# Xen HVM Hypervisor services driver
+device		xentimer		# Xen x86 PV timer device
 
 # Netmap provides direct access to TX/RX rings on supported NICs
 device		netmap			# netmap(4) support
Index: sys/conf/files
===================================================================
--- sys/conf/files
+++ sys/conf/files
@@ -3543,7 +3543,7 @@
 dev/xen/netback/netback.c	optional xenhvm
 dev/xen/netfront/netfront.c	optional xenhvm
 dev/xen/xenpci/xenpci.c		optional xenpci
-dev/xen/timer/timer.c		optional xenhvm
+dev/xen/timer/timer.c		optional xentimer
 dev/xen/pvcpu/pvcpu.c		optional xenhvm
 dev/xen/xenstore/xenstore.c	optional xenhvm
 dev/xen/xenstore/xenstore_dev.c	optional xenhvm
Index: sys/i386/conf/GENERIC
===================================================================
--- sys/i386/conf/GENERIC
+++ sys/i386/conf/GENERIC
@@ -342,9 +342,11 @@
 device		hyperv			# HyperV drivers 
 
 # Xen HVM Guest Optimizations
-# NOTE: XENHVM depends on xenpci.  They must be added or removed together.
+# NOTE: XENHVM depends on xenpci and xentimer.
+# They must be added or removed together.
 options 	XENHVM			# Xen HVM kernel infrastructure
 device		xenpci			# Xen HVM Hypervisor services driver
+device		xentimer		# Xen x86 PV timer device
 
 # evdev interface
 options 	EVDEV_SUPPORT		# evdev support in legacy drivers