RADIX_PMD_FRAG_SIZE_SHIFT   20 arch/powerpc/include/asm/book3s/64/radix-4k.h #define RADIX_PMD_FRAG_NR	(PAGE_SIZE >> RADIX_PMD_FRAG_SIZE_SHIFT)
RADIX_PMD_FRAG_SIZE_SHIFT   21 arch/powerpc/include/asm/book3s/64/radix-64k.h #define RADIX_PMD_FRAG_NR	(PAGE_SIZE >> RADIX_PMD_FRAG_SIZE_SHIFT)
RADIX_PMD_FRAG_SIZE_SHIFT  593 arch/powerpc/mm/book3s64/radix_pgtable.c 	__pmd_frag_size_shift = RADIX_PMD_FRAG_SIZE_SHIFT;