[Intel-gfx] [PATCH] drm/i915: Migrate stolen objects before hibernation

[Chris Wilson]

On Tue, Jun 30, 2015 at 12:54:02PM +0200, Daniel Vetter wrote:
> The gpu should be able so pinned for scanout is the only corner case I can
> think of atm.

Hmm. That's a nuisance. But... We can throw away all the VM bindings
that are unpinned, and then rewrite those that are left with the shmemfs
pages.

It's ugly. On migration back we would have to do a similar trick, and we
need to tell a few white lies to get past some of our internal BUG_ON.
However, as the contents are the same and the PTE writes are atomic into
the GGTT, it should be invisible to the user.

For internally allocated frontbuffers, I was expecting to mark them as
volatile and let them lose their contents across hibernation - because
they will be immediately cleared afterwards (at least so I expect).
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre