Index: sys/kern/bus_if.m
===================================================================
--- sys/kern/bus_if.m
+++ sys/kern/bus_if.m
@@ -284,6 +284,35 @@
 } DEFAULT null_alloc_resource;
 
 /**
+ * @brief Extend a system resource
+ *
+ * This method is called to extend a resource with data that describes it.
+ *
+ * @param _dev		the parent device of @p _child
+ * @param _child	the device which is requesting extension
+ * @param _type		the type of resource to extend
+ * @param _rid		a pointer to the resource identifier
+ * @param _start	hint at the start of the resource range - pass
+ *			@c 0 for any start address
+ * @param _end		hint at the end of the resource range - pass
+ *			@c ~0 for any end address
+ * @param _count	hint at the size of range required - pass @c 1
+ *			for any size
+ *
+ * @returns		interrupt data to extend the resource with or @c NULL if no
+ *			extension could be made
+ */
+METHOD struct intr_map_data * extend_resource {
+	device_t	_dev;
+	device_t	_child;
+	int		_type;
+	int		*_rid;
+	rman_res_t	_start;
+	rman_res_t	_end;
+	rman_res_t	_count;
+} DEFAULT bus_generic_extend_resource;
+
+/**
  * @brief Activate a resource
  *
  * Activate a resource previously allocated with
Index: sys/kern/subr_bus.c
===================================================================
--- sys/kern/subr_bus.c
+++ sys/kern/subr_bus.c
@@ -4036,6 +4036,23 @@
 }
 
 /**
+ * @brief Helper function for implementing BUS_EXTEND_RESOURCE().
+ *
+ * This simple implementation of BUS_EXTEND_RESOURCE() simply calls the
+ * BUS_EXTEND_RESOURCE() method of the parent of @p dev.
+ */
+struct intr_map_data *
+bus_generic_extend_resource(device_t dev, device_t child, int type, int *rid,
+    rman_res_t start, rman_res_t end, rman_res_t count)
+{
+	/* Propagate up the bus hierarchy until someone handles it. */
+	if (dev->parent)
+		return (BUS_EXTEND_RESOURCE(dev->parent, child, type, rid,
+		    start, end, count));
+	return (NULL);
+}
+
+/**
  * @brief Helper function for implementing BUS_RELEASE_RESOURCE().
  *
  * This simple implementation of BUS_RELEASE_RESOURCE() simply calls the
@@ -4425,8 +4442,6 @@
 #ifdef INTRNG
 /**
  * @internal
- *
- * This can be converted to bus method later. (XXX)
  */
 static struct intr_map_data *
 bus_extend_resource(device_t dev, int type, int *rid, rman_res_t *start,
@@ -4436,6 +4451,11 @@
 	struct resource_list *rl;
 	int rv;
 
+	imd = BUS_EXTEND_RESOURCE(dev->parent, dev, type, rid, *start, *end,
+	    *count);
+	if (imd)
+		return (imd);
+
 	if (dev->parent == NULL)
 		return (NULL);
 	if (type != SYS_RES_IRQ)
Index: sys/sys/bus.h
===================================================================
--- sys/sys/bus.h
+++ sys/sys/bus.h
@@ -421,6 +421,10 @@
 	bus_generic_alloc_resource(device_t bus, device_t child, int type,
 				   int *rid, rman_res_t start, rman_res_t end,
 				   rman_res_t count, u_int flags);
+struct intr_map_data *
+	bus_generic_extend_resource(device_t dev, device_t child, int type,
+				   int *rid, rman_res_t start, rman_res_t end,
+				   rman_res_t count);
 int	bus_generic_attach(device_t dev);
 int	bus_generic_bind_intr(device_t dev, device_t child,
 			      struct resource *irq, int cpu);