+#ifdef CONFIG_VIRTUAL_MEM_MAP
+extern struct page *vmem_map;
+#ifdef CONFIG_DISCONTIGMEM
+# define page_to_pfn(page) ((unsigned long) (page - vmem_map))
+# define pfn_to_page(pfn) (vmem_map + (pfn))
+#endif
+#endif
+
+#if defined(CONFIG_FLATMEM) || defined(CONFIG_SPARSEMEM)
+/* FLATMEM always configures mem_map (mem_map = vmem_map if necessary) */
+#include <asm-generic/memory_model.h>
+#endif
+