Index: head/sys/kern/subr_bus.c
===================================================================
--- head/sys/kern/subr_bus.c
+++ head/sys/kern/subr_bus.c
@@ -2936,6 +2936,7 @@
 	else
 		dev->state = DS_ATTACHED;
 	dev->flags &= ~DF_DONENOMATCH;
+	EVENTHANDLER_INVOKE(device_attach, dev);
 	devadded(dev);
 	return (0);
 }
@@ -2969,8 +2970,13 @@
 	if (dev->state != DS_ATTACHED)
 		return (0);
 
-	if ((error = DEVICE_DETACH(dev)) != 0)
+	EVENTHANDLER_INVOKE(device_detach, dev, EVHDEV_DETACH_BEGIN);
+	if ((error = DEVICE_DETACH(dev)) != 0) {
+		EVENTHANDLER_INVOKE(device_detach, dev, EVHDEV_DETACH_FAILED);
 		return (error);
+	} else {
+		EVENTHANDLER_INVOKE(device_detach, dev, EVHDEV_DETACH_COMPLETE);
+	}
 	devremoved(dev);
 	if (!device_is_quiet(dev))
 		device_printf(dev, "detached\n");
Index: head/sys/sys/eventhandler.h
===================================================================
--- head/sys/sys/eventhandler.h
+++ head/sys/sys/eventhandler.h
@@ -293,4 +293,15 @@
 EVENTHANDLER_DECLARE(swapon, swapon_fn);
 EVENTHANDLER_DECLARE(swapoff, swapoff_fn);
 
+/* newbus device events */
+enum evhdev_detach {
+	EVHDEV_DETACH_BEGIN,    /* Before detach() is called */
+	EVHDEV_DETACH_COMPLETE, /* After detach() returns 0 */
+	EVHDEV_DETACH_FAILED    /* After detach() returns err */
+};
+typedef void (*device_attach_fn)(void *, device_t);
+typedef void (*device_detach_fn)(void *, device_t, enum evhdev_detach);
+EVENTHANDLER_DECLARE(device_attach, device_attach_fn);
+EVENTHANDLER_DECLARE(device_detach, device_detach_fn);
+
 #endif /* _SYS_EVENTHANDLER_H_ */