diff --git a/sys/dev/acpica/acpi.c b/sys/dev/acpica/acpi.c
index f9295e2f0c23..e8cd3f4dcd47 100644
--- a/sys/dev/acpica/acpi.c
+++ b/sys/dev/acpica/acpi.c
@@ -111,15 +111,16 @@ static char	*acpi_device_id_probe(device_t bus, device_t dev, char **ids);
 static ACPI_STATUS acpi_device_eval_obj(device_t bus, device_t dev,
 		    ACPI_STRING pathname, ACPI_OBJECT_LIST *parameters,
 		    ACPI_BUFFER *ret);
-static ACPI_STATUS acpi_device_walk_ns(device_t bus, device_t dev,
-		    ACPI_OBJECT_TYPE type, UINT32 max_depth,
-		    ACPI_WALK_CALLBACK user_fn, void *context, void **ret);
+static ACPI_STATUS acpi_device_scan_cb(ACPI_HANDLE h, UINT32 level,
+		    void *context, void **retval);
+static ACPI_STATUS acpi_device_scan_children(device_t bus, device_t dev,
+		    int max_depth, acpi_scan_cb_t user_fn, void *arg);
 static int	acpi_isa_pnp_probe(device_t bus, device_t child,
-			struct isa_pnp_id *ids);
+		    struct isa_pnp_id *ids);
 static void	acpi_probe_children(device_t bus);
 static int	acpi_probe_order(ACPI_HANDLE handle, int *order);
 static ACPI_STATUS acpi_probe_child(ACPI_HANDLE handle, UINT32 level,
-			void *context, void **status);
+		    void *context, void **status);
 static BOOLEAN	acpi_MatchHid(ACPI_HANDLE h, const char *hid);
 static void	acpi_shutdown_final(void *arg, int howto);
 static void	acpi_enable_fixed_events(struct acpi_softc *sc);
@@ -169,7 +170,7 @@ static device_method_t acpi_methods[] = {
     /* ACPI bus */
     DEVMETHOD(acpi_id_probe,		acpi_device_id_probe),
     DEVMETHOD(acpi_evaluate_object,	acpi_device_eval_obj),
-    DEVMETHOD(acpi_walk_namespace,	acpi_device_walk_ns),
+    DEVMETHOD(acpi_scan_children,	acpi_device_scan_children),
 
     /* ISA emulation */
     DEVMETHOD(isa_pnp_probe,		acpi_isa_pnp_probe),
@@ -1036,20 +1037,85 @@ acpi_device_eval_obj(device_t bus, device_t dev, ACPI_STRING pathname,
 {
     ACPI_HANDLE h;
 
-    if ((h = acpi_get_handle(dev)) == NULL)
+    if (dev == NULL)
+	h = ACPI_ROOT_OBJECT;
+    else if ((h = acpi_get_handle(dev)) == NULL)
 	return (AE_BAD_PARAMETER);
     return (AcpiEvaluateObject(h, pathname, parameters, ret));
 }
 
+/* Callback arg for our implementation of walking the namespace. */
+struct acpi_device_scan_ctx {
+    acpi_scan_cb_t	user_fn;
+    void		*arg;
+    ACPI_HANDLE		parent;
+};
+
 static ACPI_STATUS
-acpi_device_walk_ns(device_t bus, device_t dev, ACPI_OBJECT_TYPE type,
-    UINT32 max_depth, ACPI_WALK_CALLBACK user_fn, void *context, void **ret)
+acpi_device_scan_cb(ACPI_HANDLE h, UINT32 level, void *arg, void **retval)
+{
+    struct acpi_device_scan_ctx *ctx;
+    device_t dev, old_dev;
+    ACPI_STATUS status;
+    ACPI_OBJECT_TYPE type;
+
+    /*
+     * Skip this device if we think we'll have trouble with it or it is
+     * the parent where the scan began.
+     */
+    ctx = (struct acpi_device_scan_ctx *)arg;
+    if (acpi_avoid(h) || h == ctx->parent)
+	return (AE_OK);
+
+    /* If this is not a valid device type (e.g., a method), skip it. */
+    if (ACPI_FAILURE(AcpiGetType(h, &type)))
+	return (AE_OK);
+    if (type != ACPI_TYPE_DEVICE && type != ACPI_TYPE_PROCESSOR &&
+	type != ACPI_TYPE_THERMAL && type != ACPI_TYPE_POWER)
+	return (AE_OK);
+
+    /*
+     * Call the user function with the current device.  If it is unchanged
+     * afterwards, return.  Otherwise, we update the handle to the new dev.
+     */
+    old_dev = acpi_get_device(h);
+    dev = old_dev;
+    status = ctx->user_fn(h, &dev, level, ctx->arg);
+    if (ACPI_FAILURE(status) || old_dev == dev)
+	return (status);
+
+    /* Remove the old child and its connection to the handle. */
+    if (old_dev != NULL) {
+	device_delete_child(device_get_parent(old_dev), old_dev);
+	AcpiDetachData(h, acpi_fake_objhandler);
+    }
+
+    /* Recreate the handle association if the user created a device. */
+    if (dev != NULL)
+	AcpiAttachData(h, acpi_fake_objhandler, dev);
+
+    return (AE_OK);
+}
+
+static ACPI_STATUS
+acpi_device_scan_children(device_t bus, device_t dev, int max_depth,
+    acpi_scan_cb_t user_fn, void *arg)
 {
     ACPI_HANDLE h;
+    struct acpi_device_scan_ctx ctx;
 
-    if ((h = acpi_get_handle(dev)) == NULL)
+    if (acpi_disabled("children"))
+	return (AE_OK);
+
+    if (dev == NULL)
+	h = ACPI_ROOT_OBJECT;
+    else if ((h = acpi_get_handle(dev)) == NULL)
 	return (AE_BAD_PARAMETER);
-    return (AcpiWalkNamespace(type, h, max_depth, user_fn, context, ret));
+    ctx.user_fn = user_fn;
+    ctx.arg = arg;
+    ctx.parent = h;
+    return (AcpiWalkNamespace(ACPI_TYPE_ANY, h, max_depth,
+	acpi_device_scan_cb, &ctx, NULL));
 }
 
 static int
diff --git a/sys/dev/acpica/acpi_if.m b/sys/dev/acpica/acpi_if.m
index c2cdc1121e18..7365d9ce3c80 100644
--- a/sys/dev/acpica/acpi_if.m
+++ b/sys/dev/acpica/acpi_if.m
@@ -33,7 +33,28 @@
 INTERFACE acpi;
 
 #
-# Default implementation for the probe method.
+# Callback function for each child handle traversed in acpi_scan_children().
+#
+# ACPI_HANDLE h:  current child device being considered
+#
+# device_t *dev:  pointer to the child's original device_t or NULL if there
+#   was none.  The callback should store a new device in *dev if it has
+#   created one.  The method implementation will automatically clean up the
+#   previous device and properly associate the current ACPI_HANDLE with it.
+#
+# level:  current level being scanned
+#
+# void *arg:  argument passed in original call to acpi_scan_children()
+#
+# Returns:  AE_OK if the scan should continue, otherwise an error
+#
+HEADER {
+	typedef ACPI_STATUS (*acpi_scan_cb_t)(ACPI_HANDLE h, device_t *dev,
+	    int level, void *arg);
+};
+
+#
+# Default implementation for acpi_id_probe().
 #
 CODE {
 	static char *
@@ -44,7 +65,16 @@ CODE {
 };
 
 #
-# Probe
+# Check a device for a match in a list of ID strings.  The strings can be
+# EISA PNP IDs or ACPI _HID/_CID values.
+#
+# device_t bus:  parent bus for the device
+#
+# device_t dev:  device being considered
+#
+# char **ids:  array of ID strings to consider
+#
+# Returns:  ID string matched or NULL if no match
 #
 METHOD char * id_probe {
 	device_t	bus;
@@ -53,7 +83,22 @@ METHOD char * id_probe {
 } DEFAULT acpi_generic_id_probe;
 
 #
-# AcpiEvaluateObject
+# Evaluate an ACPI method or object, given its path.
+#
+# device_t bus:  parent bus for the device
+#
+# device_t dev:  evaluate the object relative to this device's handle.
+#   Specify NULL to begin the search at the ACPI root.
+#
+# ACPI_STRING pathname:  absolute or relative path to this object
+#
+# ACPI_OBJECT_LIST *parameters:  array of arguments to pass to the object.
+#   Specify NULL if there are none.
+#
+# ACPI_BUFFER *ret:  the result (if any) of the evaluation
+#   Specify NULL if there is none.
+#
+# Returns:  AE_OK or an error value
 #
 METHOD ACPI_STATUS evaluate_object {
 	device_t	bus;
@@ -64,14 +109,28 @@ METHOD ACPI_STATUS evaluate_object {
 };
 
 #
-# AcpiWalkNamespace
+# Rescan a subtree and optionally reattach devices to handles.  Users
+# specify a callback that is called for each ACPI_HANDLE of type Device
+# that is a child of "dev".
 #
-METHOD ACPI_STATUS walk_namespace {
+# device_t bus:  parent bus for the device
+#
+# device_t dev:  begin the scan starting with this device's handle.
+#   Specify NULL to begin the scan at the ACPI root.
+# 
+# int max_depth:  number of levels to traverse (i.e., 1 means just the
+#   immediate children.
+#
+# acpi_scan_cb_t user_fn:  called for each child handle
+#
+# void *arg:  argument to pass to the callback function
+#
+# Returns:  AE_OK or an error value, based on the callback return value
+#
+METHOD ACPI_STATUS scan_children {
 	device_t	bus;
 	device_t	dev;
-	ACPI_OBJECT_TYPE type;
-	UINT32		max_depth;
-	ACPI_WALK_CALLBACK user_fn;
-	void		*context;
-	void		**ret;
+	int		max_depth;
+	acpi_scan_cb_t	user_fn;
+	void		*arg;
 };