# Cooler Master Devastator Scroll Lock issue



## tsudico (Jul 21, 2017)

I have a Cooler Master Devastator keyboard. It allows you to toggle its LED back-lighting with Scroll Lock.

I have recently installed FreeBSD in a VM (VirtualBox on Windows 10) so I can explore a Unix-like OS. It uses Scroll Lock to control console scrolling.

The problem I run across is that the keyboard's back-light is on when Scroll Lock is on, and off otherwise. There is no way to change this behavior for the keyboard that I know of beyond altering the hardware. I have tried adjusting the keyboard map so that different keys activate scroll lock using information from this mailing list topic: Keyboard without Scroll Lock. The result is that any key or combination of keys that are adjusted to act like Scroll Lock will cause the back-light to turn on and off depending on the state of Scroll Lock. The same thing happens when trying to use the Pause key.

Is there a way to change the default behavior of FreeBSD so that scroll locking can be done using a different key or a combination of keys instead of changing what keys are mapped to Scroll Lock? I would prefer a configuration file change instead of editing FreeBSD source code.

Thank you.


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## steinex (Jul 22, 2017)

Unfortunately i have no definitive answer for you, but have a look at uhidd:
https://wiki.freebsd.org/uhidd

I use it, and got multimedia-keys and backlight on my gaming-keyboard working with it. I guess by using it, you could find out how to split up backlight / scroll lock.

I know that's not much input, but with a bit of fiddling, it should be possible at least, i guess


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## tsudico (Jul 31, 2017)

Unfortunately, it seems that the backlight is toggled based on the status of the Scroll Lock LED, so anything that alters the state of Scroll Lock(i.e. the Scroll Lock LED state) will toggle the backlight as well. This leads me to believe that the only way to fix the keyboard is a hardware based solution.

That is why I was looking to see if there was a way to alter the behavior of FreeBSD when it comes to Scroll Lock. If I could set FreeBSD to use a different key to actually do the console scroll which doesn't affect the state of Scroll Lock, I wouldn't have to resort to adjusting my keyboard. If that isn't possible, then the only option would be to alter the hardware of the keyboard itself.


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## ralphbsz (Aug 1, 2017)

Impractical suggestion: Find the console tty driver in the source code, change it, recompile, boot.  It's actually not very difficult, since FreeBSD is designed around the whole system being built from source, so you do actually get easily compilable source code (unlike Linux, where getting the real kernel source code to a Ubuntu or RedHat system is a complex voyage of discovery, which starts with Linus' kernel at kernel.org, and goes through a confusing maze of patches).  For an experienced kernel developer, this would probably take 10 minutes.

For most other people, it's probably faster to take a soldering iron the the keyboard and rewire the LEDs.


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