Good timezone! I am brand new to Linux and have been testing distros on an old Levnovo Ideapad laptop. The laptop itself has had a brightness issue forever on Win where the buttons change the “brightness” setting, but the actual brightness stays the same, and I wasn’t able to figure out a fix.
I decided to move foward with my Linux tests anyway, and see if I could figure it out with a more open system. I was able to find a fix for it when I was using Linux Mint, which I will describe below. I have not been able to figure out how to fix it yet using Fedora KDE. I am wondering if you could help me to
- know what the fix I did on Mint actually did
and
- know how to fix it on KDE.
Thanks!
Previous Fix:
When using Mint, I tried a few fixes found on “Easy Linux Tips Project” and eventually got the below to work.
terminal:
xed admin:///etc/default/grub
In grub text file, edit
GRUB_CMDLINE_LINUX=“”
to
GRUB_CMDLINE_LINUX=“acpi_osi=Linux”
Save and close.
sudo update-grub
Then reboot. Worked like a charm. This same thing does not work on Fedora KDE, and am wondering what this did and how to replicate it.
Thanks again!
Adding this flag to the kernel parameters tells the kernel to identify itself as “Linux” when the BIOS firmware asks “what Operating System are you?”. This way the BIOS and the motherboard firmware knows what to expect, what’s using it and ensure it runs control code designed to be operated by a specific OS. As you’d expect, Windows announces itself as “Windows” and perhaps surprisingly perversely so do most Linux flavours.
This is deliberate - many BIOS manufacturers don’t bother to test their code against Linux and as a result we get either no support at all for blacklight control, special keys, volume controls, and suchlike, or it’s buggy and/or broken if it works at all.
As such, many Linux distros tell the firmware that they are Windows just to reduce the amount of breakage which will probably ensue from declaring itself to be Linux as that code path received no support or limited support and testing.
In this case, you’re telling the kernel to come out and announce to the world it’s Linux and proud. Might work, might not.
In your case, on this Ideapad, it seems that the BIOS code to handle the backlight keys and control the backlight depending on what keys were pressed works perfectly well in Linux mode and I’d expect it to work just as well in Fedora as Mint (or any other distro for that matter), as it’s evidently the BIOS which is controlling the backlights and if it works for one Linux kernel, it should work for all of them (in theory!)
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