This bug is a duplicate of https://bugs.launchpad.net/ubuntu/+source/linux/+bug/776999
I can confirm the following workaround allows full brightness control: nox2apic kernel param AND In Device section of xorg.conf: Option "RegistryDwords" "EnableBrightnessControl=1" -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/992720 Title: [Lenovo E420s] Hitting brightness keys causes machine to lock up To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/992720/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
