Originally Posted by artem
What Aaron just says is that NVIDIA doesn't currently officially supports multiseat (NVIDIA GPU driving different video outputs).
Running two X servers which share the same configuration and the same output has been always possible (in fact I'm running such a configuration without any problems - switching between users using Ctrl + Alt + F7/F8 buttons).
I suppose nouveau developers will make multiseat possible (if it's not available already).
That's a relief to hear.
However, it brings back my original problem: Exiting any of the X servers while any of the other X servers (or itself) is in the foreground crashes the machine entirely. This was not the case with older versions of the driver. "nvidia-173" (ubuntu parlance) exhibits this problem. This happens with different video cards even. I tried submitting a debug dump, but there seems to be no interest in this. I wonder if I'm the only one with this problem.