Exposing monitor layout to desktop managers

Hi!

I'd like to have a standard / generic way of exposing virtual monitor layout to desktop managers. This would then serve as a *hint* to those managers to set the desktop up accordingly.

Of course, this is mostly for virtual hardware, since without accelerometers, gyros and gps positioners on monitors, the kernel wouldn't be able to know where the user put his monitors.

One could argue that this is purely user-space policy, but since those managers monitor the kms interface anyway it would be a convenient place to expose this information.

One idea would to place the x,y location in an output property.

Another idea would be to send new layout for all connected output as a drm event.

Any ideas, comments etc. would be appreciated.

Thanks, Thomas