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I've just installed Ubuntu 11.10 with a LiveCD. During the installation, nothing was shown on screen unless I plugged in an external monitor. Same thing happens within Ubuntu.

I have an Emachines E525. Could this just be a backlight issue or something? It works fine on Windows though. If anyone could help, that'd be great. Please explain everything throughly if you can though, I'm new to all of this.

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so how it worked? –  Kangarooo Jan 6 '13 at 3:04
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2 Answers

This is a known bug: https://bugs.launchpad.net/ubuntu/+source/acpid/+bug/392948
See comments #23 and #24.

Workaround is to add acpi_osi=Linux to the kernel cmdline:

One-line solution (use at your own risk)

sudo sed -i 's/GRUB_CMDLINE_LINUX_DEFAULT=\"\(.*\)\"/GRUB_CMDLINE_LINUX_DEFAULT=\"\1 acpi_osi=Linux\"/' /etc/default/grub && sudo update-grub

Manual method

  1. edit /etc/default/grub file:

    sudo gedit /etc/default/grub
  2. Add acpi_osi=Linux to the GRUB_CMDLINE_LINUX_DEFAULT variable so it will look like

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_osi=Linux"

  1. Update GRUB:

    sudo update-grub
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sudo gedit /etc/default/grub

change line in there adding just acpi_osi=Linux so it looks likeGRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_osi=Linux" then

sudo update-grub

on start u need to change brightness once on some comps. If thats the case like for Emachines e525 then also do this so that on start brightness would be max

sudo gedit etc/rc.local

before exit 0 put setpci -s 00:02.0 F4.B=00

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