Stefan, Here is the dmesg log while booting with the acpi_backlight=vendor option. The only change I notice is that the brightness applet on the panel says it can't get the brightness level. To your question: with this model of Acer notebook brightness control did work douring the brief time between the patched kernel you upload (while I was using Ubuntu 9.04) and the following kernel update. After that I could not go back. Under /sys/class/backlight ther is only a shortcut to a directory named acer-wmi (look at the attached image) I've installed 9.04 again on another disk partition of the same laptop. I attached 2 files: * dmesg-9.04-01.txt (obtained with 9.04 just installed; brightness control doesn't work) * dmesg-9.04-02.txt (after installing the patched kernel; brightness control works fine) I hope it would help 2009/12/14 Stefan Bader