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During 32-bit Ubuntu 12.04 LTS installation on HP laptops, the back-light goes off and become unable to proceed.
I've experienced it on many hp laptops.
Do anyone provide the reason or a solution for the problem.

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Firstly try to increase or decrease the brightness (Using keyboard hot keys) if it is not working Use a external monitor for installation (or you can use a torch light to see what's going on the screen), after installation boot the Ubuntu and do the following changes.

you need to make this changes permanent by editing /etc/default/grub Do this by typing in the terminal:

Press Control+Alt+t (It will opens the terminal)

sudo gedit /etc/default/grub

This will open a text file that you can then edit. It could also ask for your admin password which you should provide. Find a line that looks like this:


Now edit it to look like this:

GRUB_CMDLINE_LINUX_DEFAULT="quiete splash acpi_osi=Linux"

Save the file and then update grub2 by typing in the command line:

sudo update-grub2

After it is done, reboot the system and it should be done (Try to increase the brightness).

NOTE: You may also need to edit another file especially if the login screen is dim and requires the use of the brightness buttons.To keep it permanent, you will have to edit /etc/rc.local. Open the file by typing in the CLI (command line interface):

sudo gedit /etc/rc.local

Look at the end section of the file and just before the line ‘exit 0;‘, add this line of code:

setpci -s 00:02 F4.B=00

This should solve all of your problems for all except that when the machine goes into sleep mode, you will have to use the brightness button of your machine to bring it back on.

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