[Intel-gfx] [PATCH] drm/i915: Fix context size calculation on SNB/IVB/VLV

[Ben Widawsky]

On Thu, Aug 22, 2013 at 07:23:13PM +0300, ville.syrjala at linux.intel.com wrote:
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> 
> All the different context sizes reported in the CXT_SIZE register
> aren't meant to be simply added together.
> 
> While BSpec is somewhat unclear on the topic of the actual context
> size, empirical tests have now revealed the truth. So let's add a
> big fat comment to remind people how it all works.

By the way. I've done some digging. I believe (75% certain) pre-HSW,
every context save writes the entire data. So if you wanted to set some
pattern and see what HW actually overwrites, it should be doable. HSW+
though we can't do that.

[snip]
-- 
Ben Widawsky, Intel Open Source Technology Center