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Blank screen during install

November 30th, 2013 No comments

I had some problems while installing Ubuntu/Linux Mint on a laptop. The screen went blank.
After some investigation it turned out that the backlight was turned off. (Intel GMA 4500m chipset)
To fix this I found two options that worked (default brightness buttons on laptop were not working)

Add the following boot options:

acpi_osi=Linux

This option allows me to use the brightness controls on the laptop and thus restore the brightness to a viewable state.
If that doesn’t work you could also turn off i915. That will allow you to pass the setup at first. Maybe install an OpenSSH server and then go in to output a acceptable value into the backlight.

i915.modeset=0

After this I created a init.d script called backlight to set the backlight to a valid value at boot.

First I got the current value:

cat /sys/class/backlight/intel_backlight/actual_brightness
72250

Use that in the backlight script.

#!/bin/sh
echo 72250 > /sys/class/backlight/intel_backlight/brightness

This will probably only work when acpi_osi=Linux during boot. You can add that option to grub later on.
Edit (/etc/default/grub) add the rule to GRUB_CMDLINE_LINUX_DEFAULT, GRUB_CMDLINE_LINUX or GRUB_CMDLINE_DEFAULT and run update-grub2 afterwards.

Make it executable.

chmod +x backlight

Make it run at different runlevels.

update-rc.d backlight defaults 00

That should restore the backlight at some point during boot. Not an ideal solution, but at least a working one.

Categories: Linux, Ubuntu Tags: , , ,