linux-kernel - Re: [PATCH] x86-64: use EFI to deal with platform wall clock

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Date:	Tue, 15 May 2012 14:20:06 +0100
From:	Matthew Garrett <mjg59@...f.ucam.org>
To:	Jan Beulich <JBeulich@...e.com>
Cc:	mingo@...e.hu, tglx@...utronix.de, matt.fleming@...ux.intel.com,
	linux-kernel@...r.kernel.org, hpa@...or.com
Subject: Re: [PATCH] x86-64: use EFI to deal with platform wall clock

On Tue, May 15, 2012 at 02:19:07PM +0100, Jan Beulich wrote:

> I would have expected that things work that way, but they
> don't. In particular is the function in efi_64.c that's being
> modified here called from efi_call_phys_{pro,epi}log(), and at
> that point we can't expect virtual addresses to be uniformly
> set yet. So it's a physical call that requires the fixup done
> here, as efi_set_executable() simply expects ->virt_addr to
> be valid. I suspect that no physical calls other than
> phys_efi_set_virtual_address_map() were being done so far
> at all on 64-bit, hiding the problem.

In that case we need to split the mapping code into two chunks and 
configure the memory map earlier. You can't depend on __va() doing 
anything useful on runtime addresses.

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