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

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Message-ID: <20130619164822.GA28240@srcf.ucam.org>
Date:	Wed, 19 Jun 2013 17:48:22 +0100
From:	Matthew Garrett <mjg59@...f.ucam.org>
To:	Borislav Petkov <bp@...en8.de>
Cc:	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 Wed, Jun 19, 2013 at 06:38:04PM +0200, Borislav Petkov wrote:
> On Wed, Jun 19, 2013 at 05:21:15PM +0100, Matthew Garrett wrote:
> > Yes, kexec needs a different solution.
> 
> No need. If we say, "efi=use_11_map", the 1:1 map will be shoved down
> SetVirtualAddressMap. Otherwise the high mappings.

Ah, sure - if we're willing to take an argument then we can leave it at 
that. But having a stable set of high addresses for UEFI is also an 
option.

> > Because firmware images don't always update all of the pointers, and
> > so will crash if the 1:1 mappings aren't present.
> 
> Ok, so it sounds like we want to *always* create both mappings but,
> depending on what we want, to shove down SetVirtualAddressMap a
> different set. And the 1:1 map will be the optional one which we give
> SetVirtualAddressMap only when user wants it, i.e. when booting with
> "efi=1:1_map".

Yup, I think that sounds ideal.

-- 
Matthew Garrett | mjg59@...f.ucam.org
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