PMD_MASKED_BITS   250 arch/powerpc/include/asm/book3s/64/pgtable.h #define PMD_MASKED_BITS		0xc0000000000000ffUL
PMD_MASKED_BITS    45 arch/powerpc/include/asm/nohash/64/pgtable-4k.h #define PMD_MASKED_BITS		0