Index: kernel/generic/include/console/kconsole.h
===================================================================
--- kernel/generic/include/console/kconsole.h	(revision da1bafb8cf9a3b3be8ef21bc114daaa476a85190)
+++ kernel/generic/include/console/kconsole.h	(revision 48dcc699ceb1979a093dbc5c8b698fe7f16536ed)
@@ -47,4 +47,6 @@
 	ARG_TYPE_INT,
 	ARG_TYPE_STRING,
+	/** Optional string */
+	ARG_TYPE_STRING_OPTIONAL,
 	/** Variable type - either symbol or string. */
 	ARG_TYPE_VAR