tux-mobile:/# Xgl -fullscreen :0 -ac -accel glx:pbuffer -accel xv:pbuffer & sleep 2 && DISPLAY=:0
[1] 3839

Fatal server error:
Server is already active for display 0
        If this server is no longer running, remove /tmp/.X0-lock
        and start again.

[1]+  Exit 1                  Xgl -fullscreen :0 -ac -accel glx:pbuffer -accel xv:pbuffer
tux-mobile:/#