Thanks. Then, if they work, I "only" have to find out how to make FN buttons working, at least these that control sound volume and brightness. And I had the impression that the CPU use was worse, or the power management worse, for the same usage patterns (when not doing anything special like compiling, just editing or browsing), fan turned on more often.

Edit: I'm reading about "libinput" that it has "palm detection" but it's certainly not my problem with the pseudo "noise." Even when I hold only and just one finger, the mouse cursor "trembles" and "shakes."

You could first check via `xev` whether the key presses actually arrive in software. For me they did, but my desktop environment didn't adjust the brightness if an `XF86MonBrightnessUp` event fired.

Same with my Chromebook, once you know the events arrive it was a simple mapping in Xubuntu.

Manual mapping shouldn't be required for most current desktop environments. GNOME and KDE certainly do, and I think Unity does as well. If your desktop environment doesn't map those keys by default, please file a bug against it.

It's great that Linux makes it possible to manually fix such things, but it's even better when they work out of the box.

> Edit: I'm reading about "libinput" that it has "palm detection" but it's certainly not my problem with the pseudo "noise." Even when I hold only and just one finger, the mouse cursor "trembles" and "shakes."

libinput also adds better noise filtering, finger position precision, and other improved algorithms. I found it quite an improvement even on my current laptop with a great touchpad, and on another laptop it made the difference between usable and unusable.

As someone else alluded to, Fn key presses can be weird - they could show up as novel key inputs, which xev would show you, or as odder things.