PTRS_PER_PGD_SHIFT  129 arch/ia64/include/asm/pgtable.h #define PTRS_PER_PGD		(1UL << PTRS_PER_PGD_SHIFT)
PTRS_PER_PGD_SHIFT  243 arch/ia64/include/asm/pgtable.h #define RGN_MAP_SHIFT (PGDIR_SHIFT + PTRS_PER_PGD_SHIFT - 3)