Debian: dmesg output contains “Error: Driver ‘pcspkr’ is already registered, aborting…”

Well, I recently prepared a bunch of Debian KVM guests, and today I got annoyed (basically because logwatch complains about it …) by this pesky error message on each startup. What causes this is error is really simple.

Udev loads the PC speaker driver (pcspkr) and then (for whatever reason) tries to load the alsa-module for the PC speaker (snd_pcsp). And the second one, basically fails. All we need to do, is create a blacklist.conf and add the latter one to it.