Brightness function keys not working on Slackware64 & Slackware64 current
 

I have a problem with brightness function keys on my Lenovo laptop. They are not working with Slackware64 14.2 or Slackware64 current.

I've tried some possible solutions suggested online (such as appending different settings to lilo.conf), but to no avail. However, when I tried Alien Bob's Slackware64 live plasma5 current, I've found that everything is working out of the box.

Would anybody have an idea what could be the exact cause of this difference, so I could configure my Slackware64 current installation the same way?

What model do you have??

Works perfectly fine on my T450s and T550 with -Current and Xfce / Mate, also loaded up Plasma5 and zero issues.

It's Ideapad 520s. I gave a chance to Xfce too, it didn't help. Which kernel do you use? I tried Slackware64 14.2 and Slackware64 current, using default (huge) kernel with both.

I'm using Alien's Slackware live at the moment. It's Plasma 5 version, but it's the same with the other live versions, they too do OK with brightness Fn keys. I installed it to HDD and everything works well, but I'm afraid I can't use slackpkg to upgrade all packages without breaking something (or everything).

Usually I get problems of this type resolved by following advice from corresponding ThinkWiki page.

Any difference with loaded acpi modules between the Slackware versions?
Boot parameter comparison between working and non-working versions?

Meanwhile I installed the latest Slackware64 current. The idea was to check for parameters ferrari suggested earlier and to compare with those found in Slackware live. However, after installing this version, Fn keys worked as they should be. So, the problem disappeared somewhere between the October version of Slackware64 current (it's what I had before I installed Slackware live) and the latest Slackware64 current update. Thank you all for your suggestions!

For future reference, the little program xev(1) is very handy for detecting things like dead keys and buttons. It basically prints all input events received by X. Helpfun for finding out the correct strings for X configuration files as well.

Thanks!