[Intel-gfx] [PATCH v2 for -fixes] drm/i915: Disable stolen memory when DMAR is active

[Jani Nikula]

On Wed, 19 Mar 2014, David Woodhouse <dwmw2 at infradead.org> wrote:
> On Tue, 2014-03-18 at 14:59 +0200, Jani Nikula wrote:
>> From: Chris Wilson <chris at chris-wilson.co.uk>
>> 
>> We have reports of heavy screen corruption if we try to use the stolen
>> memory reserved by the BIOS whilst the DMA-Remapper is active. This
>> quirk may be only specific to a few machines or BIOSes, but first lets
>> apply the big hammer and always disable use of stolen memory when DMAR
>> is active.
>> 
>> v2 by Jani: Rebase on -fixes, only look at intel_iommu_gfx_mapped.
>
> Perhaps this (and all similar workarounds) should be predicated on
> i915_preliminary_hw_support? When people are using the Linux kernel for
> chipset validation, we sure as hell don't want to silently disable this
> stuff and let them think it's working when it's not.

Or an additional knob, in case it's really not working and people want
to get other things depending on prelim hw support done.

BR,
Jani.


-- 
Jani Nikula, Intel Open Source Technology Center