__PHYSICAL_MASK_SHIFT is used to define the mask that helps to extract
physical address from a page table entry.

Although, real physical address space available may differ between
machines, it's safe to use 52 as __PHYSICAL_MASK_SHIFT. Unused bits
above log2(MAXPHYADDR) up to bit 51 are reserved and must be 0.

Signed-off-by: Kirill A. Shutemov <kirill.shute...@linux.intel.com>
---
 arch/x86/include/asm/page_64_types.h | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/page_64_types.h 
b/arch/x86/include/asm/page_64_types.h
index e1407312c412..f68e6526891d 100644
--- a/arch/x86/include/asm/page_64_types.h
+++ b/arch/x86/include/asm/page_64_types.h
@@ -52,11 +52,12 @@
 #define __START_KERNEL_map     _AC(0xffffffff80000000, UL)
 
 /* See Documentation/x86/x86_64/mm.txt for a description of the memory map. */
-#ifdef CONFIG_X86_5LEVEL
+
 #define __PHYSICAL_MASK_SHIFT  52
+
+#ifdef CONFIG_X86_5LEVEL
 #define __VIRTUAL_MASK_SHIFT   56
 #else
-#define __PHYSICAL_MASK_SHIFT  46
 #define __VIRTUAL_MASK_SHIFT   47
 #endif
 
-- 
2.15.1

Reply via email to