Comment 76 for bug 281732

Confirming this bug on an R400 running Maverick. The xev still doesn't report anything when pressing Mute button. The Volume Up/Down buttons work fine and show the OSD volume change. The mute button mutes, but the muteness doesn't register with the mixer applet or anything else, except that the mute state is noted in /proc/acpi/ibm/volume. It doesn't unmute, to unmute a volume up/down button needs to be pressed.

While I understand that telling ACPI that Linux is not Windows might lead to side effects, I am not sure pretending to be Windows is a good policy in the long run. Wouldn't this make kernel vulnerable to potential incompatibility bugs? Why does upstream insist on doing it this way?

I don't understand the argument about not letting Mute key events into user space. Why not? I understand it is already operating on BIOS mixer, but something needs to react to this by updating user interface. How is it supposed to work, check the BIOS mixer state all the time?