Brightness control works in Byzantium but does not work in Crimson

Software PureOS
1

Hello everyone,
For a few years I have been using PureOS Byzantium on a iMac 27". The Mac is from 2012 (Intel i5; NVIDIA GeForce GTX 660M), everything is OK. I recently wanted to install PureOS Crimson and in this case the brightness control does not work. I noticed that in Crimson the folder /sys/class/backlight/ is empty, while in Byzantium there is this folder /sys/class/backlight/acpi_video0 and inside it has the following content:

actual_brightness
bl_power
brightness
device
max_brightness
power
scale
subsystem
type
uevent

How can I install in Crimson the same thing that is installed in Byzantium?

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2

I don’t have an answer to your question but I want to instead ask you: are there some special tricks needed to install something like PureOS on a Mac like you did?

I mean, with a more normal computer the procedure I’m used to is that I cownload a .iso file and use that to prepare a bootable USB stick, then reboot the computer and find some sort of “boot menu” or similar and select to boot from the USB stick, and then the installer starts and everything is fine. But with a Mac, I’m afraid there will now be any such boot menu. I don’t really know, I just expect that it will not work on a Mac without jumping through some extra hoops. Do you need to do something to “unlock” it first?

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3

Likewise, I don’t have an answer to your question but I am not sure that crimson is ready for prime-time yet. I mean, sure, a Mac is never going to be inside the support boundary anyway but, for example, maybe the same problem happens on crimson with other hardware and that just hasn’t been addressed yet. (So, for example, as fault isolation, if you can find someone running crimson on a Librem 14, you could ask for a listing of that directory.)

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