Re: [PATCH 6/6] drm/i915: Create VMAs

[Chris Wilson <chris@chris-wilson.co.uk>]

On Wed, Jul 17, 2013 at 12:19:03PM -0700, Ben Widawsky wrote:
> Formerly: "drm/i915: Create VMAs (part 1)"
> 
> In a previous patch, the notion of a VM was introduced. A VMA describes
> an area of part of the VM address space. A VMA is similar to the concept
> in the linux mm. However, instead of representing regular memory, a VMA
> is backed by a GEM BO. There may be many VMAs for a given object, one
> for each VM the object is to be used in. This may occur through flink,
> dma-buf, or a number of other transient states.
> 
> Currently the code depends on only 1 VMA per object, for the global GTT
> (and aliasing PPGTT). The following patches will address this and make
> the rest of the infrastructure more suited
> 
> v2: s/i915_obj/i915_gem_obj (Chris)
> 
> v3: Only move an object to the now global unbound list if there are no
> more VMAs for the object which are bound into a VM (ie. the list is
> empty).
> 
> v4: killed obj->gtt_space
> some reworks due to rebase
> 
> v5: Free vma on error path (Imre)
> 
> v6: Another missed vma free in i915_gem_object_bind_to_gtt error path
> (Imre)
> Fixed vma freeing in stolen preallocation (Imre)

Big-bada-boom; set-cache-level needs to iterate over vma, and in
particular should not dereference a non-existent one. Or if we decided
that set-cache-level was a ggtt only property, just not explode if there
is no global vma.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre