diff --git a/[refs] b/[refs]
index dc8d9f2cd8a5..d38f4137f124 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 3af283e1141474925b33383425bbe038e75fd03a
+refs/heads/master: 3989170f8e3c1bd71d8f7ec6e3d52e46815ee096
diff --git a/trunk/drivers/acpi/acpica/evxfregn.c b/trunk/drivers/acpi/acpica/evxfregn.c
index 541cbc1544d5..ce9314f79451 100644
--- a/trunk/drivers/acpi/acpica/evxfregn.c
+++ b/trunk/drivers/acpi/acpica/evxfregn.c
@@ -64,6 +64,12 @@ ACPI_MODULE_NAME("evxfregn")
  *
  * DESCRIPTION: Install a handler for all op_regions of a given space_id.
  *
+ * NOTE: This function should only be called after acpi_enable_subsystem has
+ * been called. This is because any _REG methods associated with the Space ID
+ * are executed here, and these methods can only be safely executed after
+ * the default handlers have been installed and the hardware has been
+ * initialized (via acpi_enable_subsystem.)
+ *
  ******************************************************************************/
 acpi_status
 acpi_install_address_space_handler(acpi_handle device,