Comment 37 for bug 281732

Isn't this bug an extension of bug #357673? The thinkpad_acpi kernel maintainer has said he's opposed to forwarding these keypresses to userspace, on the grounds that the kernel behavior is already consistent with how these keys operate under Windows - controlling the hardware/BIOS mixer instead of acting on the OS mixer.

In fact, I see Henrique has commented in the upstream bug, apparently to exactly this effect.