[Intel-gfx] [PATCH 39/48] drm/i915: Do not allow buffers at offset 0

[Chris Wilson]

On Fri, Dec 06, 2013 at 02:11:24PM -0800, Ben Widawsky wrote:
> This is primarily a band aid for an unexplainable error in
> gem_reloc_vs_gpu/forked-faulting-reloc-thrashing. Essentially as soon as
> a relocated buffer (which had a non-zero presumed offset) moved to
> offset 0, something goes bad. Since I have been unable to solve this,
> and potentially this is a good thing to do anyway, since many things can
> accidentally write to offset 0, why not?

A better hack would have been to exclude the first page from the vm->mm,
so that we didn't then introduce a change to ggtt.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre