Commit ff3d0a12 authored by Matt Fleming's avatar Matt Fleming Committed by Ingo Molnar

Documentation/x86: Update EFI memory region description

Make it clear that the EFI page tables are only available during
EFI runtime calls since that subject has come up a fair numbers
of times in the past.

Additionally, add the EFI region start and end addresses to the
table so that it's possible to see at a glance where they fall
in relation to other regions.
Signed-off-by: default avatarMatt Fleming <>
Reviewed-by: default avatarBorislav Petkov <>
Acked-by: default avatarBorislav Petkov <>
Cc: Andrew Morton <>
Cc: Andy Lutomirski <>
Cc: Andy Lutomirski <>
Cc: Ard Biesheuvel <>
Cc: Borislav Petkov <>
Cc: Brian Gerst <>
Cc: Dave Jones <>
Cc: Denys Vlasenko <>
Cc: H. Peter Anvin <>
Cc: Linus Torvalds <>
Cc: Peter Zijlstra <>
Cc: Sai Praneeth Prakhya <>
Cc: Stephen Smalley <>
Cc: Thomas Gleixner <>
Cc: Toshi Kani <>
Link: default avatarIngo Molnar <>
parent 67a9108e
......@@ -16,6 +16,8 @@ ffffec0000000000 - fffffc0000000000 (=44 bits) kasan shadow memory (16TB)
... unused hole ...
ffffff0000000000 - ffffff7fffffffff (=39 bits) %esp fixup stacks
... unused hole ...
ffffffef00000000 - ffffffff00000000 (=64 GB) EFI region mapping space
... unused hole ...
ffffffff80000000 - ffffffffa0000000 (=512 MB) kernel text mapping, from phys 0
ffffffffa0000000 - ffffffffff5fffff (=1525 MB) module mapping space
ffffffffff600000 - ffffffffffdfffff (=8 MB) vsyscalls
......@@ -32,11 +34,9 @@ reference.
Current X86-64 implementations only support 40 bits of address space,
but we support up to 46 bits. This expands into MBZ space in the page tables.
We map EFI runtime services in the aforementioned PGD in the virtual
range of 64Gb (arbitrarily set, can be raised if needed)
0xffffffef00000000 - 0xffffffff00000000
We map EFI runtime services in the 'efi_pgd' PGD in a 64Gb large virtual
memory window (this size is arbitrary, it can be raised later if needed).
The mappings are not part of any other kernel PGD and are only available
during EFI runtime calls.
-Andi Kleen, Jul 2004
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