Re: [PATCH 01/03] drm/i915: add a context parameter to {en, dis}able zero address mapping

Daniel Vetter
2015-05-28T15:49:53Z

On Thu, May 28, 2015 at 03:39:26PM +0100, Chris Wilson wrote:
> On Wed, May 20, 2015 at 05:00:13PM +0300, David Weinehall wrote:
> > Export a new context parameter that can be set/queried through the
> > context_{get,set}param ioctls. This parameter is passed as a context
> > flag and decides whether or not a GPU address mapping is allowed to
> > be made at address zero. The default is to allow such mappings.
>
> Please revert this piece of unreviewed API.
>
> The most obvious objection is what value of bias the kernel should be
> using.
>
> Then given that what value does this hold over and above userspace
> specifying the layout they want?

Yeah it would be redundant with softpinning. But that's only for ocl2, and
this is apparently needed for for ocl1.x already. Hence imo it's ok to
pull this ahead a bit, even if redundant.
-Daniel
--
Daniel Vetter
Software Engineer, Intel Corporation