Re: [PATCH 00/03] Preventing zero GPU virtual address allocation

Chris Wilson
2015-05-20T14:14:09Z

On Wed, May 20, 2015 at 03:09:43PM +0100, Chris Wilson wrote:
> On Wed, May 20, 2015 at 04:54:19PM +0300, David Weinehall wrote:
> > This patch series (one patch each for libdrm, the kernel, and beignet)
> > aims to provide a means to add a context-specific means to prevent
> > a mapping to GPU virtual address zero. This is needed at least by
> > Beignet (possibly in other use-cases too, though I don't know of any
> > other) to allow use of address zero to represent NULL.
>
> Urm, you cannot allow absolute addressing period. What happens to the
> object at 0 when the user reads from it or writes to it? You have to
> have an object at 0 for the user's NULL pointer access.

I'll mollify that: outside of full-ppgtt where you need to share the VM.
-Chris

--
Chris Wilson, Intel Open Source Technology Centre