What is the purpose of the upstart configuration /etc/init/udev-fallback-graphics.conf (shown below) in Ubuntu 14.04 LTS?
# fallback-graphics - take actions to initiate fallback graphics
#
# if we have cold plugged everything and not yet seen a valid graphics
# device,
# shove a fallback framebuffer into the mix and hope for the best.
description "load fallback graphics devices"
# We only want this job to happen once per boot, hence 'startup and ...'.
start on (startup and
(graphics-device-added PRIMARY_DEVICE_FOR_DISPLAY=1
or drm-device-added PRIMARY_DEVICE_FOR_DISPLAY=1
or stopped udevtrigger or container))
task
script
if [ "$PRIMARY_DEVICE_FOR_DISPLAY" = "" ]; then
modprobe -q -b vesafb
fi
end script
I would think it would rarely be invoked, unless a video graphics driver is missing. If a graphics driver is missing, there's still no guarantee that modprobe -b -q vesafb will succeed. If it fails, the script exits with the return code from modprobe and /var/log/boot.log will contain a message similar to the following:
* Starting load fallback graphics devices[74G[[31mfail[39;49m]
The message is not very informative. The script code in the upstart configuration looks like a kludge to me. I would rather see a specific warning or error message displayed if the return code from modprobe indicates failure, e.g.,
modprobe -q -b vesafb || echo "No suitable graphics driver found."
