On an SL410 there are four buttons to the left of the keyboard: mute mic, volume up, volume down and mute.
Neither of them show up when using xev or showkey. The Volume Up and Down keys work, but not the mute mic or mute volume ones.
You can get the keycodes by monitoring dmesg -- pushing Mute volume three times I get
[ 2392.912282] hda-intel: spurious response 0x0:0x0, last cmd=0x1439000 [ 2393.447050] hda-intel: spurious response 0x0:0x0, last cmd=0x1439000 [ 2393.930206] hda-intel: spurious response 0x0:0x0, last cmd=0x1439000
The problem is that the keycode keeps changing -- the mute key has a different value depending on what the volume is.
mute mic ????? vol up/down 0x1439080,0x339080,00,09,13,1b,21,25,29,2d,30,33 mut vol 0x1439000, 339029
You'll probably find that thinkpad_acpi is loaded:
sudo rmmod thinkpad_acpi
Now press the mute button -- did an orange light show under it? That means it's working.
I think the issue is that SL410 isn't a true thinkpad -- it's really an ideapad and the firmware doesn't match.
To make the change permanent,
edit /etc/modprobe.d/thinkpad-blacklist.confblacklist thinkpad_acpi
thinkpad_acpi shouldn't load on boot anymore.
Mute mic still doesn't work.