It's a bit of both. I believe Apple maintain the app-facing side of the GL implementation. Backend plugins are provided by IHVs to talk to their specific hardw

It's a bit of both. I believe Apple maintain the app-facing side of the GL implementation. Backend plugins are provided by IHVs to talk to their specific hardware, but with Apple still controlling the release channels. AFAIK there's no route for an IHV to get an updated driver to a user without going through Apple, put it that way.