Comment 7 for bug 1550972

Nvidia Prime is a bit deceiving here. Prime typically works by wiring the Intel GPU to the display and just using the Nvidia chip for indirect rendering (if desired).

And that's what's going on here too. Mir does not support the Nvidia driver, but it started successfully because Mir is actually just using the Intel graphics driver:

[2016-02-28 19:27:03.147913] mirplatform: Found graphics driver: mir:mesa-kms (version 0.20.0)
[2016-02-28 19:27:03.147975] mirplatform: Found graphics driver: mir:mesa-x11 (version 0.20.0)
qtmir.mir: MirServer created
[2016-02-28 19:27:03.148721] mirserver: Starting
[2016-02-28 19:27:03.298794] mirserver: Using nested cursor
[2016-02-28 19:27:03.445320] mirserver: Initial display configuration:
[2016-02-28 19:27:03.445621] mirserver: 0.34: eDP 15,3" 340x190mm
[2016-02-28 19:27:03.445633] mirserver: Current mode 3840x2160 47,99Hz
[2016-02-28 19:27:03.445648] mirserver: Preferred mode 3840x2160 47,99Hz
[2016-02-28 19:27:03.445653] mirserver: Logical position +0+0
[2016-02-28 19:27:03.445661] mirserver: 0.31: unused VGA
[2016-02-28 19:27:03.445667] mirserver: 0.42: unused HDMI-A

7f1e67234000-7f1e6780b000 r-xp 00000000 00:15 4064527 /usr/lib/x86_64-linux-gnu/dri/i965_dri.so
7f1e6780b000-7f1e67a0b000 ---p 005d7000 00:15 4064527 /usr/lib/x86_64-linux-gnu/dri/i965_dri.so
7f1e67a0b000-7f1e67a3c000 r--p 005d7000 00:15 4064527 /usr/lib/x86_64-linux-gnu/dri/i965_dri.so
7f1e67a3c000-7f1e67a43000 rw-p 00608000 00:15 4064527 /usr/lib/x86_64-linux-gnu/dri/i965_dri.so

The crash is occurring still, unfortunately because of Nvidia prime. You have Unity8 starting, but trying to use the wrong libGL (the Nvidia one which we don't support). The reason why USC will work here, but Unity8 won't is possibly because USC is native GLESv2, but Unity8/QtMir on desktop uses full GL. So you may not encounter a crash till Unity8 starts.

Still, we have started up OK apparently using Intel graphics. I wonder if we can make Unity8 find the correct libGL...