[Intel-gfx] [RFC] drm/i915: Framebuffers need not be limited to 256MB on gen8+.

[Chris Wilson]

On Thu, Feb 26, 2015 at 09:01:52PM +0530, deepak.s at linux.intel.com wrote:
> From: Deepak S <deepak.s at linux.intel.com>
> 
> The restriction of pinningFramebuffer to first 256MB is removed from gen8+.
> Removing the restriction so that FB can be pinned in any space within
> GTT/PPGTT. Also, for gen8+ no need to use pin_mappable for Framebuffer &
> also we do not take fence as Framebuffer compression is not enabled.

Not quite, the reason why we restrict the framebuffer to mappable was
that certain display servers depend upon being able to GTT mmap the
framebuffer for direct access. Thus they would crash if we found that the
framebuffer was already pinned in an unreachable location. That legacy
code is currently still able to run on gen8+ and so you need to have
userspace request an ABI break...
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre