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

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Message-ID: <20130619162115.GA28119@srcf.ucam.org>
Date:	Wed, 19 Jun 2013 17:21:15 +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 06:18:27PM +0200, Borislav Petkov wrote:
> On Wed, Jun 19, 2013 at 05:08:04PM +0100, Matthew Garrett wrote:
> > But, as always, the only reliable thing to do here is to behave as
> > much like Windows as possible. Which means performing the 1:1 mapping
> > but maintaining the high mapping, and passing the high values via
> > SetVirtualAddressMap.
> 
> We can't pass the high values via SetVirtualAddressMap and have EFI
> runtime in the kexec-ed kernel, as you and I established last week. And
> since not all would want EFI runtime in the kexec-ed kernel, I'm leaning
> more towards a boot-time option which enables the 1:1 mapping.

Yes, kexec needs a different solution.

> Btw, why would you even want the 1:1 mappings if we pass the high values
> via SetVirtualAddressMap?

Because firmware images don't always update all of the pointers, and so 
will crash if the 1:1 mappings aren't present.

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