Re: [RFC][PATCH 6/6] staging: android: ion: Introduce new ioctls for dynamic heaps

[Brian Starkey]

Hi Laura,

On Wed, Jun 08, 2016 at 12:14:12PM -0700, Laura Abbott wrote:
> For now I'm just going to focus on comments not about the heap ID mapping
> because I'm leaning towards dropping the heap ID mapping.

Fair enough. Like you said, giving userspace enough information to just
figure out the right heap IDs is already a big improvement.

> I'm not that familiar with the DRM ioctls but this sounds like a
> good suggestion. One less ioctl to worry about.

Sorry, I probably should have pointed to an example:
http://lxr.free-electrons.com/source/drivers/gpu/drm/drm_crtc.c#L2325

> > > + */
> > > +struct ion_heap_query {
> > > +    __u32 cnt; /* Total number of heaps to be copied */
> > > +    __u64 heaps; /* buffer to be populated */
> >
> > I guess this field needs explicit alignment to 64 bits
>
> Yes, I was going by the suggestion in botching-up-ioctls.txt
>
> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/ioctl/botching-up-ioctls.txt#n42

The type is fine, but you should add a 32-bit padding field before
heaps:
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/ioctl/botching-up-ioctls.txt#n32

Cheers,

-Brian