[Intel-gfx] [PATCH 1/3] drm/i915: Added a new 'I915_CPU_MAP_NOT_NEEDED' flag to gem_create ioctl.

['Chris Wilson']

On Mon, Mar 10, 2014 at 04:12:23PM +0000, Gupta, Sourab wrote:
> 
> Hi Chris,
> 
> For the issue mentioned by you ( regarding botching up ioctls), we understand that this is related to the 
> compatibility between the older/newer versions of driver/userspace.
> In our old implementation, the 'pad' field was replaced with 'flags' in the ioctl structure. This would have 
> led to the erroneous behavior when the new userspace is communicating with old driver.

You missed the important point that there is no guarrantee that current
userspace is not stuffing garbage into the pad field. It is.

You have to go with a new ioctl. So you may as well design one that
tries to fulfil today's varied needs for a constructor.  For example,
here's one I prepared earlier,
http://cgit.freedesktop.org/~ickle/linux-2.6/commit/?h=create2&id=401fa740adcaf252d0149cdd63d5fdf5e3969907
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre