Hey Erik,

Op 07-06-12 19:35, Erik Gilling schreef:

On Thu, Jun 7, 2012 at 1:55 AM, Maarten Lankhorst m.b.lankhorst@gmail.com wrote:

...

I haven't looked at intel and amd, but from a quick glance it seems like they already implement fencing too, so just some way to synch up the fences on shared buffers seems like it could benefit all graphics drivers and the whole userspace synching could be done away with entirely.

It's important to have some level of userspace API so that GPU generated graphics can participate in the graphics pipeline. Think of the case where you have a software video codec streaming textures into the GPU. It needs to know when the GPU is done with those textures so it can reuse the buffer.

In the graphics case this problem already has to be handled without dma-buf, so adding any extra synchronization api for userspace that is only used when the bo is shared is a waste.

I do agree you need some way to synch userspace though, but I think adding a new api for userspace is not the way to go.

Cheers, Maarten

PS: re-added cc's that seem to have fallen off from your mail.