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

Brian Starkey brian.starkey at arm.com
Thu Jun 9 08:25:02 UTC 2016


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


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