linux-kernel - Re: [PATCH 6/6] Documentation/x86: Update EFI memory region description

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Date:	Fri, 13 Nov 2015 09:29:06 +0000
From:	Matt Fleming <matt@...eblueprint.co.uk>
To:	Ingo Molnar <mingo@...nel.org>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	"H . Peter Anvin" <hpa@...or.com>, Toshi Kani <toshi.kani@...com>,
	linux-kernel@...r.kernel.org, linux-efi@...r.kernel.org,
	Borislav Petkov <bp@...en8.de>,
	Sai Praneeth Prakhya <sai.praneeth.prakhya@...el.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Dave Jones <davej@...emonkey.org.uk>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Andy Lutomirski <luto@...nel.org>,
	Denys Vlasenko <dvlasenk@...hat.com>,
	Stephen Smalley <sds@...ho.nsa.gov>
Subject: Re: [PATCH 6/6] Documentation/x86: Update EFI memory region
 description

On Fri, 13 Nov, at 10:22:10AM, Ingo Molnar wrote:
> 
> * Matt Fleming <matt@...eblueprint.co.uk> wrote:
> 
> > +We map EFI runtime services in the efi_pgd PGD in the virtual range of
> > +64Gb (arbitrarily set, can be raised if needed). The mappings are not
> > +part of any other kernel PGD and are only available during EFI runtime
> > +calls.
> 
> Is that virtual address range 0-64Gb, i.e.:
> 
> 	0x00000000.00000000 - 0x00000010.00000000
> 
> or is it somewhere else?

You've snipped the patch hunk that gives the address range used,

diff --git a/Documentation/x86/x86_64/mm.txt
b/Documentation/x86/x86_64/mm.txt
index 05712ac83e38..a9885bb1ac22 100644
--- a/Documentation/x86/x86_64/mm.txt
+++ b/Documentation/x86/x86_64/mm.txt
@@ -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
--
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