[Linaro-mm-sig] [RFCv2 PATCH 4/9] v4l: add buffer exporting via dmabuf

[Daniel Vetter]

On Thu, Mar 22, 2012 at 03:07:18PM +0100, Laurent Pinchart wrote:
> > >> + * Contains data used for exporting a video buffer as DMABUF file
> > >> + * descriptor. Uses the same 'cookie' as mmap() syscall. All reserved
> > >> fields
> > >> + * must be set to zero.
> > >> + */
> > >> +struct v4l2_exportbuffer {
> > >> +	__u32		fd;
> > >> +	__u32		reserved0;
> > > 
> > > Why is there a reserved field here ?
> > 
> > +1 to Laurent. Any particular need for reserved0 and reserved[13] below?
> > I think one void user pointer is sufficient even for future need.
> 
> I'd rather have more than one void user pointer, just in case. A couple of 
> bytes won't be expensive, and they will save lots of hassle in the future if 
> we need to add a couple of fields. I was just wondering why there was a 
> reserved field between fd and mem_offset.

Quick comment from a random bystander: __u32 is not big enough for a void*
pointer from userspace ...
-Daniel
-- 
Daniel Vetter
Mail: daniel at ffwll.ch
Mobile: +41 (0)79 365 57 48