linux-kernel - Re: [PATCH -v2 0/4] EFI 1:1 mapping

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Message-ID: <51C383AC.4060706@zytor.com>
Date:	Thu, 20 Jun 2013 15:35:24 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Borislav Petkov <bp@...en8.de>
CC:	Matthew Garrett <mjg59@...f.ucam.org>,
	James Bottomley <James.Bottomley@...senPartnership.com>,
	Ingo Molnar <mingo@...nel.org>,
	Linux EFI <linux-efi@...r.kernel.org>,
	Matt Fleming <matt@...sole-pimps.org>, X86 ML <x86@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>, Borislav Petkov <bp@...e.de>
Subject: Re: [PATCH -v2 0/4] EFI 1:1 mapping

On 06/20/2013 11:47 AM, Borislav Petkov wrote:
> 
> I guess we can do a top-down allocation, starting from the highest
> virtual addresses:
> 
> EFI_HIGHEST_ADDRESS
> |
> | size1
> |
> --> region1
> |
> | size2
> |
> --> region2
> 
> ...
> 
> and we make EFI_HIGHEST_ADDRESS be the same absolute number on every
> system.
> 
> hpa, is this close to what you had in mind? It would be prudent to
> verify whether this will suit well with the kexec virtual space layout
> though...
> 

This would work really well, I think.  The tricky part here is to pick a
safe EFI_HIGHEST_ADDRESS as it is an ABI.

My preference would be to make EFI_HIGHEST_ADDRESS = -4 GB, which is
*not* what Windows uses, but will leave the high negative range clear,
and allows a range where we can grow down without much risk of
interfering with anything else.

	-hpa


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