x86/mm: Update memory map description to list hypervisor-reserved area

Peter Anvin says: > 0xffff880000000000 is the lowest usable address because we have > agreed to leave 0xffff800000000000-0xffff880000000000 for the > hypervisor or other non-OS uses. Let's call this out in the documentation. This came up during the kernel address sanitizer discussions where it was proposed to use this area for other kernel things. Signed-off-by: Dave Hansen <[email protected]> Cc: Andrey Ryabinin <[email protected]> Cc: Dmitry Vyukov <[email protected]> Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]>
marineam · Sep 19, 2014 · beb9147 · beb9147
1 parent 8477957
commit beb9147
Showing 1 changed file with 1 addition and 1 deletion.
diff --git a/Documentation/x86/x86_64/mm.txt b/Documentation/x86/x86_64/mm.txt
@@ -5,7 +5,7 @@ Virtual memory map with 4 level page tables:
 
 0000000000000000 - 00007fffffffffff (=47 bits) user space, different per mm
 hole caused by [48:63] sign extension
-ffff800000000000 - ffff80ffffffffff (=40 bits) guard hole
+ffff800000000000 - ffff87ffffffffff (=43 bits) guard hole, reserved for hypervisor
 ffff880000000000 - ffffc7ffffffffff (=64 TB) direct mapping of all phys. memory
 ffffc80000000000 - ffffc8ffffffffff (=40 bits) hole
 ffffc90000000000 - ffffe8ffffffffff (=45 bits) vmalloc/ioremap space