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-rw-r--r--Documentation/x86_64/mm.txt6
1 files changed, 5 insertions, 1 deletions
diff --git a/Documentation/x86_64/mm.txt b/Documentation/x86_64/mm.txt
index 662b73971a6..133561b9cb0 100644
--- a/Documentation/x86_64/mm.txt
+++ b/Documentation/x86_64/mm.txt
@@ -6,7 +6,7 @@ Virtual memory map with 4 level page tables:
0000000000000000 - 00007fffffffffff (=47bits) user space, different per mm
hole caused by [48:63] sign extension
ffff800000000000 - ffff80ffffffffff (=40bits) guard hole
-ffff810000000000 - ffffc0ffffffffff (=46bits) direct mapping of phys. memory
+ffff810000000000 - ffffc0ffffffffff (=46bits) direct mapping of all phys. memory
ffffc10000000000 - ffffc1ffffffffff (=40bits) hole
ffffc20000000000 - ffffe1ffffffffff (=45bits) vmalloc/ioremap space
... unused hole ...
@@ -14,6 +14,10 @@ ffffffff80000000 - ffffffff82800000 (=40MB) kernel text mapping, from phys 0
... unused hole ...
ffffffff88000000 - fffffffffff00000 (=1919MB) module mapping space
+The direct mapping covers all memory in the system upto the highest
+memory address (this means in some cases it can also include PCI memory
+holes)
+
vmalloc space is lazily synchronized into the different PML4 pages of
the processes using the page fault handler, with init_level4_pgt as
reference.