Andreas Heider

Ah, I guess 10.15 also updated the EFI then? Can you try building apple_set_os.efi with https://github.com/0xbb/apple_set_os.efi/blob/master/apple_set_os.c#L12 changed to `#define APPLE_SET_OS_VERSION "Mac OS X 10.15"` or something like that?

Try the docker build method: https://github.com/0xbb/apple_set_os.efi#build-via-docker

Or try this: [apple_set_os.zip](https://github.com/0xbb/apple_set_os.efi/files/3722057/apple_set_os.zip) Warning: Completely untested :D

I sadly really don't remember how I originally figured out the string, I think it was via looking at the Mac kernel image. Or at the efi binaries. Either way...

So I had a look today, and for me (MBP 13,3, Catalina) `#define APPLE_SET_OS_VERSION "Mac OS X 10.15"` just works:  Could you maybe try this? [apple_set_os.zip](https://github.com/0xbb/apple_set_os.efi/files/3877561/apple_set_os.zip) And post the...

Hmm, I'm not sure then, I can just run it multiple times. Maybe something changed on newer macbooks. It's weird that you can run it once, I wonder why. Maybe...

@ronnieyuyiwei I can't really debug this since it doesn't happen on my laptop and I don't have access to anything else. But if you want to help maybe try the...

Nice, that's quite a workaround. I'm impressed it works :D

Sorry, I just don't quite know what's wrong. I suspect this is some efi variable protection introduced in recent kernels, but I might be completely wrong about that. The script...

It probably picks the wrong backlight driver, try finding the gmux one in /sys and setting the brightness by writing to the brightness file.