[PATCH 1/2] drm/shmem: Use cached mappings by default

[Gerd Hoffmann]

> > $ git grep drm_gem_shmem_mmap
> > 
> > We also need correct access from userspace, otherwise the gpu is going to
> > be sad.
> 
> I've been thinking about this, and I think it means that we can never
> have cached mappings anywhere. Even if shmem supports it internally for
> most drivers, as soon as the page are exported, the importer could
> expect uncached memory.

The importer should not expect anything but call dma-buf ops so the
exporter has a chance to handle this correctly.

(Yes, we don't get this right everywhere, some drivers take the dma-bufs
list of pages and do their own thing ...).

take care,
  Gerd