Question on UAPI for fences

[Christian König]

Hello everyone,

to allow concurrent buffer access by different engines beyond the 
multiple readers/single writer model that we currently use in radeon and 
other drivers we need some kind of synchonization object exposed to 
userspace.

My initial patch set for this used (or rather abused) zero sized GEM 
buffers as fence handles. This is obviously isn't the best way of doing 
this (to much overhead, rather ugly etc...), Jerome commented on this 
accordingly.

So what should a driver expose instead? Android sync points? Something else?

Please discuss and/or advise,
Christian.