Re: [RFC] drm/i915: Add variable gem object size support to i915

[Damien Lespiau <damien.lespiau@intel.com>]

On Wed, Jun 25, 2014 at 02:26:52PM +0100, Tvrtko Ursulin wrote:
> >That's a good question to ask a GL team. In the light of sparse
> >textures I think the region idea would be better.
> >
> >We would need to define what the coordinates mean, for instance:
> >   - 2D view of the buffer, and the kernel takes care of translating what
> >     it means for the underlying pages?
> >   - See the buffer object as an array of pages, and those numbers define
> >     a region of pages.
> 
> This would mean kernel has to know about all possible tiling
> formats? Would that be asking a bit too much (of the kernel)?

Not if we see the buffer as an (2D) array of pages.

> How (im)possible would it be to allocate backing store on demand, on
> page by page basis, on write rather than on binding into address
> space?

I think Chris would be very upset to lose the performance benefit of
pre-faulting the correct pages?

-- 
Damien