Multi-monitor (xinerama/mergefb) support in RandR

[Benjamin Herrenschmidt]

> No, EXA really shouldn't need to know anything about scanout buffers --
> they're just another scratch pixmap whose pointer happens to point at
> framebuffer.  If your driver wants to relocate where the screen is in
> memory, I think it would just have to get the screen pixmap and modify
> the pointer and pitch to the new location.

Well.. they also need to be pinned...

> The fb implementation wouldn't be able to split a single screen pixmap
> into two separate memory buffers.  To do that you have to go to
> traditional multihead with multiple screens.