Re: [PATCH] iommu/intel: disable DMAR for Q35 integrated gfx

From: Kees Cook
Date: Mon Dec 05 2016 - 17:18:37 EST


On Mon, Dec 5, 2016 at 2:07 PM, David Woodhouse <dwmw2@xxxxxxxxxxxxx> wrote:
> On Mon, 2016-12-05 at 13:58 -0800, Kees Cook wrote:
>> This blacklists the Q35 integrated graphics so IOMMU can be otherwise
>> enabled. Without this, a Q35 system can only enable IOMMU when booting
>> with "intel_iommu=on,igfx_off" but not "intel_iommu=on".
>
> Hm, is this definitely the same bug? Or is it something different, and
> perhaps a BIOS issue? There are many of those...

Hm, I have no idea. :) What would I look for in the BIOS?

I figured since g4 was busted, surely q35 was too, since it's even older...

-Kees

--
Kees Cook
Nexus Security