linux-kernel - Re: [PATCH 2/2] iommu: dmar -- reserve mmio space used by IOMMU

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Date:	Wed, 06 Jun 2012 09:26:23 +0100
From:	David Woodhouse <dwmw2@...radead.org>
To:	Ingo Molnar <mingo@...nel.org>
Cc:	Don Dutile <ddutile@...hat.com>, iommu@...ts.linux-foundation.org,
	mingo@...e.hu, linux-kernel@...r.kernel.org, chrisw@...hat.com,
	suresh.b.siddha@...el.com
Subject: Re: [PATCH 2/2] iommu: dmar -- reserve mmio space used by IOMMU

On Wed, 2012-06-06 at 10:16 +0200, Ingo Molnar wrote:
> So basically the patch-set is fine as-is, we just want a 
> sufficiently nasty sounding warning message about the BIOS bug, 

No. The other change that's required is that the warning and the
workaround need to trigger even when IOMMU support isn't built into the
kernel. This BIOS bug can bite you even when you aren't *using* the
IOMMU.

> If we could integrate Coreboot into the kernel and could build a 
> bzImage that one could write into the BIOS flash image and thus 
> have an updated and functional BIOS, that would be awesome.

People *have* used the kernel as a Coreboot payload, but it's not really
the best solution. For anything but deeply embedded devices, you
probably do want a real firmware of some kind (like Tianocore).

The point in having hardware which is fully supported by Coreboot is
that it gives you the choice. You *can* do the above, or more sensibly
you can use it to deploy an up-to-date and working Tianocore without the
type of bugs that we're discussing here. Or at least without the ones
which offend *you*.

-- 
dwmw2

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