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I just installed Xubuntu 13.04 on a new Dell XPS 13 Ultrabook. When I boot up the screen brightness is EXTREMELY dim. Adjusting the screen brightness doesn't do anything. This is obviously a very new bug with 13.04.

Any ideas?

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here are a couple kernel boot parameters you can try

  • acpi_osi=Linux
  • acpi_backlight=vendor
  • acpi_osi='!Windows 2012'

This is there you add that code, I had to use the 3ed one to get mine working right, it may be necessary to use 1 or 3 combined with the second one
The file to edit is :
once you edit it run sudo update-grub then reboot

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never ever seen acpi_osi='!Windows 2012' ... – Qasim Apr 27 '13 at 3:33
i got it from a kernel dev here – GM-Script-Writer-62850 Apr 27 '13 at 3:44
i did google ...ty for updating the information... – Qasim Apr 27 '13 at 3:45

Along with @GM-Script-Writer-62850's answer, if you're using an EFI BIOS boot, you ned to go into the BIOS setup and set "Load Legacy Rom" to Enabled.

I have experimented with the minimal GRUB line to get this working and I only need acpi_osi=Linux

AFAIK Legacy is anything not Windows 8, and I've not experienced any performance hit.

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