Re: [PATCH] drm/i915: Declare the swizzling unknown for L-shaped configurations

[Daniel Vetter <daniel@ffwll.ch>]

On Thu, Jul 30, 2015 at 08:05:07AM +0100, Chris Wilson wrote:
> On Sun, Jun 28, 2015 at 09:19:26AM +0100, Chris Wilson wrote:
> > The old style of memory interleaving swizzled upto the end of the
> > first even bank of memory, and then used the remainder as unswizzled on
> > the unpaired bank - i.e. swizzling is not constant for all memory. This
> > causes problems when we try to migrate memory and so the kernel prevents
> > migration at all when we detect L-shaped inconsistent swizzling.
> > However, this issue also extends to userspace who try to manually detile
> > into memory as the swizzling for an individual page is unknown (it
> > depends on its physical address only known to the kernel), userspace
> > cannot correctly swizzle.
> > 
> > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=91105
> > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> > Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> > Cc: stable@vger.kernel.org
> 
> Daniel since you dropped v2 and had already reviewed this version, it
> would have been useful had you done the swap...

Simply forgot, sorry. I added a note about the earlier attempt and also
one to explain that cc: stable is for fixing up wc mmaps.

Picked up for -fixes, thanks for the patch.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch