__PHYSICAL_MASK_SHIFT   13 include/asm-x86/page.h #define __PHYSICAL_MASK		((phys_addr_t)(1ULL << __PHYSICAL_MASK_SHIFT) - 1)
__PHYSICAL_MASK_SHIFT  231 include/asm-x86/pgtable_64.h #define PTE_FILE_MAX_BITS __PHYSICAL_MASK_SHIFT