#ifndef __ASSEMBLY__
#include <linux/types.h>
+
+/*
+ * pfn_t: encapsulates a page-frame number that is optionally backed
+ * by memmap (struct page). Whether a pfn_t has a 'struct page'
+ * backing is indicated by flags in the high bits of the value.
+ */
+typedef struct {
+ u64 val;
+} pfn_t;
#endif
#define PFN_ALIGN(x) (((unsigned long)(x) + (PAGE_SIZE - 1)) & PAGE_MASK)