powerpc/mm/64: Document the sizes of/sizes mapped by Pxx_INDEX_SIZE

[linux-2.6-block.git] / arch / powerpc / include / asm / book3s / 64 / radix-4k.h

diff --git a/arch/powerpc/include/asm/book3s/64/radix-4k.h b/arch/powerpc/include/asm/book3s/64/radix-4k.h
index 863c3e8286fbfb448a26a60361c31b0825422756..d5f5ab73dc7ff3dfde96679a6b5953decf0d819d 100644 (file)
--- a/arch/powerpc/include/asm/book3s/64/radix-4k.h
+++ b/arch/powerpc/include/asm/book3s/64/radix-4k.h
@@ -5,10 +5,11 @@
 /*
  * For 4K page size supported index is 13/9/9/9
  */
-#define RADIX_PTE_INDEX_SIZE  9  /* 2MB huge page */
-#define RADIX_PMD_INDEX_SIZE  9  /* 1G huge page */
-#define RADIX_PUD_INDEX_SIZE    9
-#define RADIX_PGD_INDEX_SIZE  13
+#define RADIX_PTE_INDEX_SIZE   9  // size: 8B <<  9 =  4KB, maps 2^9  x    4K =   2MB
+#define RADIX_PMD_INDEX_SIZE   9  // size: 8B <<  9 =  4KB, maps 2^9  x   2MB =   1GB
+#define RADIX_PUD_INDEX_SIZE   9  // size: 8B <<  9 =  4KB, maps 2^9  x   1GB = 512GB
+#define RADIX_PGD_INDEX_SIZE  13  // size: 8B << 13 = 64KB, maps 2^13 x 512GB =   4PB
+
 /*
  * One fragment per per page
  */