H_PUD_INDEX_SIZE    7 arch/powerpc/include/asm/book3s/64/hash-4k.h #define H_PUD_INDEX_SIZE  9  // size: 8B << 9 = 4KB, maps: 2^9 x 256MB = 128GB
H_PUD_INDEX_SIZE    7 arch/powerpc/include/asm/book3s/64/hash-64k.h #define H_PUD_INDEX_SIZE  10  // size: 8B << 10 = 8KB, maps 2^10 x 16GB = 16TB