[Intel-gfx] [PATCH v2] drm/i915: Avoid writing relocs with addresses in non-canonical form

[Daniel Vetter]

On Fri, Dec 04, 2015 at 05:41:11PM +0000, Winiarski, Michal wrote:
> On Fri, 2015-12-04 at 17:18 +0100, Daniel Vetter wrote:
> > On Fri, Dec 04, 2015 at 04:20:43PM +0100, Michał Winiarski wrote:
> > > According to bspec, some parts of HW expect the addresses to be in
> > > a canonical form, where bits [63:48] == [47]. Let's convert
> > > addresses to
> > > canonical form prior to relocating and return converted offsets to
> > > userspace.
> > > 
> > > v2: Whitespace fixup, gen8_canonical_addr description (Chris,
> > > Ville)
> > > 
> > > Cc: Chris Wilson <chris at chris-wilson.co.uk>
> > > Cc: Michel Thierry <michel.thierry at intel.com>
> > > Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > > Signed-off-by: Michał Winiarski <michal.winiarski at intel.com>
> > 
> > Can we igt this? Maybe with softpin or whatever ... For cpu address
> > space
> > negative addresses are for the kernel, but I think on the gpu we can
> > do
> > them.
> 
> Yup - would definitely be useful, I can add something to one of the
> existing reloc tests, but without softpin it's tricky to cover this in
> a reliable way (not to mention corner cases).

Oh without softpin it's going to be impossible I think ;-)
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch