linux-kernel - Re: [PATCH] BGRT: Don't ioremap if image address is in System RAM (was: Re: BGRT Pointer in System RAM)

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Date:	Tue, 16 Jul 2013 20:08:09 -0400
From:	Parag Warudkar <parag.lkml@...il.com>
To:	Andy Lutomirski <luto@...capital.net>
Cc:	linux-acpi@...r.kernel.org,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Josh Triplett <josh@...htriplett.org>
Subject: Re: [PATCH] BGRT: Don't ioremap if image address is in System RAM
 (was: Re: BGRT Pointer in System RAM)

On Tue, Jul 16, 2013 at 7:32 PM, Andy Lutomirski <luto@...capital.net> wrote:
> Fair enough.  I leave it to the experts to comment on whether there
> should be some explicit check of whether this is
> EFI_BOOT_SERVICES_DATA.
>
I am reading the code again and something doesn't sound right. The
original code calls efi_lookup_mapped_address.
It doesn't find the image address there - which is strange given that
on my system the address lies in mem type 4 as printed during boot.

Hmm. But then phys_to_virt on the same address succeeds and we can
read the image off of that.
I might need to do some debugging of efi_lookup_mapped_address to see
why it isn't finding it there. If it did find it there, none of the
ioremap issues would arise.

> FWIW, if my board does indeed have a DWORD-swapped address, it's in
> plain old RAM (type=7).

Yeah, for the status invalid case I think we would be better off just
ignoring it. Too much heuristic trickery required and it might not be
worth it after all that if the firmware didn't bother putting a proper
image in there.

Parag
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