PMD_TABLE_BIT      21 arch/arm/include/asm/pgtable-3level-hwdef.h #define PMD_TABLE_BIT		(_AT(pmdval_t, 1) << 1)
PMD_TABLE_BIT     120 arch/arm64/include/asm/pgtable-hwdef.h #define PMD_TABLE_BIT		(_AT(pmdval_t, 1) << 1)