[PATCH v4 3/3] compositor-drm: allow to be a wl_dmabuf server

[Thomas Hellstrom]

On 01/10/2014 04:23 PM, Rob Clark wrote:
> On Tue, Jan 7, 2014 at 1:37 PM, Thomas Hellstrom <thellstrom at vmware.com> wrote:
>> Conclusion: Avoid using dma-buf mmap() outside of drivers that know
>> exactly what they are
>> doing, and avoid it at all cost.
>
> well, to be fair, if you are using a gpu on the client side and pixman
> backend on the server side, you probably deserve the results.
>
> Not to say that we shouldn't come up with a better way for sw access
> to dmabuf, but just saying there are folks out there who would find
> Benjamin's patch useful in it's current state (for example, platforms
> where you have open src bits for video decoder but not for gpu).
>
> So I wouldn't block this patch strictly because we don't have a better
> mmap story yet.

I'm not sure I am in a position to block anything here, but in any case
I disagree.

Simply because if we allow this now, I'm quite sure it will spread
because there are other people that will find this useful and use this
implementation as an example and a motivation for doing the same thing
in other places.
IMHO to allow dma-buf mmap into generic code, it needs to be accompanied
by a damage interface that is mandatory and makes people think twice.

/Thomas


 

>
> BR,
> -R