+/*
+ * ZERO_PAGE is a global shared page that is always zero: used
+ * for zero-mapped memory areas etc..
+ */
+extern unsigned long empty_zero_page[];
+#define ZERO_PAGE(vaddr) (virt_to_page(empty_zero_page))
+
+extern pgd_t swapper_pg_dir[];
+
+extern void paging_init(void);
+
+/*
+ * kern_addr_valid is intended to indicate whether an address is a valid
+ * kernel address. Most 32-bit archs define it as always true (like this)
+ * but most 64-bit archs actually perform a test. What should we do here?
+ */
+#define kern_addr_valid(addr) (1)
+
+#define io_remap_pfn_range(vma, vaddr, pfn, size, prot) \
+ remap_pfn_range(vma, vaddr, pfn, size, prot)
+