Mir fails to start when a TV is connected by HDMI...
$ sudo mir_demo_server_shell --display-config=single --vt 1
ERROR: /build/buildd/mir-0.8.0+14.10.20141010/src/platform/graphics/mesa/display.cpp(141): Throw in function virtual void mir::graphics::mesa::Display::configure(const mir::graphics::DisplayConfiguration&)
Dynamic exception type: N5boost16exception_detail10clone_implINS0_19error_info_injectorISt11logic_errorEEEE
std::exception::what: Invalid or inconsistent display configuration
$ sudo mir_demo_server_shell --display-config=sidebyside --vt 1
ERROR: /build/buildd/mir-0.8.0+14.10.20141010/src/platform/graphics/mesa/display.cpp(141): Throw in function virtual void mir::graphics::mesa::Display::configure(const mir::graphics::DisplayConfiguration&)
Dynamic exception type: N5boost16exception_detail10clone_implINS0_19error_info_injectorISt11logic_errorEEEE
std::exception::what: Invalid or inconsistent display configuration
X works fine... but suspiciously reports that the TV has no "preferred" mode (+), which could possibly be what's confusing Mir:
$ env DISPLAY=:0 xrandr
Screen 0: minimum 8 x 8, current 3840 x 2160, maximum 32767 x 32767
eDP1 connected primary 1366x768+1366+0 (normal left inverted right x axis y axis) 256mm x 144mm
1366x768 60.0*+
1360x768 59.8 60.0
1024x768 60.0
800x600 60.3 56.2
640x480 59.9
HDMI1 connected 3840x2160+0+0 (normal left inverted right x axis y axis) 1872mm x 1053mm
4096x2160 24.0 24.0
3840x2160 24.0* 30.0 25.0 30.0 24.0
1920x1080 60.0 50.0 59.9 30.0 25.0 24.0 30.0 24.0
1920x1080i 60.1 50.0 60.0
1680x1050 59.9
1600x900 60.0
1280x1024 75.0 60.0
1440x900 59.9
1366x768 59.8
1280x800 59.9
1152x864 75.0
1280x720 60.0 60.0 50.0 59.9
1440x576i 50.1
1024x768 75.1 70.1 60.0
1440x480i 60.1 60.1
832x624 74.6
800x600 72.2 75.0 60.3
720x576 50.0
720x480 60.0 59.9
640x480 75.0 72.8 66.7 60.0 59.9
720x400 70.1
VIRTUAL1 disconnected (normal left inverted right x axis y axis)