[Intel-gfx] dg1 flag for userspace to allocate contig resources

[Ville Syrjälä]

On Fri, Sep 11, 2020 at 03:27:07PM +0300, Joonas Lahtinen wrote:
> + Jani and Ville
> 
> Quoting Matthew Auld (2020-09-11 11:56:56)
> > On 11/09/2020 06:42, Dave Airlie wrote:
> > > I've just been looking at the current DG1 uapi, and I can't see any
> > > flag to allow userspace to upfront say it was a contiguous vram BO.
> > > 
> > > I think you'd really want this for scanout, since otherwise you'll
> > > have to migrate any non-contig to contig when it transitions to
> > > scanout, and cause an extra set of copies.
> > 
> > Hmm, why do we need physically contiguous memory for scanout? From hw 
> > pov it's seen through the GTT.
> 
> That's correct. On both discrete (and integrated) platforms the scan-out
> addresses on Intel GPUs are programmed to targer Global GTT managed by
> kernel. So no need to have the backing storage contiguous.

The only exception being the ye olde gen2/3 physical cursor stuff :)

-- 
Ville Syrjälä
Intel