Index: kernel/generic/include/mm/as.h
===================================================================
--- kernel/generic/include/mm/as.h	(revision 6aeca0d025e83224a241ae34369bc498a25cfa1d)
+++ kernel/generic/include/mm/as.h	(revision 9befb0d53289152fee41ce5a6b25b80f10a20185)
@@ -169,4 +169,8 @@
 /** Backend data stored in address space area. */
 typedef union mem_backend_data {
+	/* anon_backend members */
+	struct {
+	};
+
 	/** elf_backend members */
 	struct {
@@ -181,4 +185,10 @@
 		bool anonymous;
 	};
+
+	/** user_backend members */
+	struct {
+		int pager;	/**< Phone to the pager. */
+	};
+
 } mem_backend_data_t;
 
@@ -296,4 +306,5 @@
 extern mem_backend_t elf_backend;
 extern mem_backend_t phys_backend;
+extern mem_backend_t user_backend;
 
 /* Address space area related syscalls. */