Impossible to change brightness in guest OS?

[fuvimos]

Hello everyone,

when I try to change the brightness of the monitor (27 inch 5k iMac, 2020 model) within the guest OS (Linux Mint 21, Cinnamon), nothing happens. Is this maybe a limitation of VMWare Fusion (12.2.4) or type 2 hypervisors in general?

[Technogeezer]

Can't say for "type 2 hypervisors in general" but yes, it does appear to be a Fusion limitation.

If you think about it, what does "change the brightness of the monitor" really mean for a virtual graphics adapter or screen? A virtual display is just a window on the host operating system. You could argue if changing the "brightness" of a window should propagate itself to the physical screen of the host (which would impact all of its other windows).

[ColoradoMarmot]

Correct, can't be done because there's no direct hardware connection of the monitor (I believe that's true of all hypervisors).  It's a virtualized graphics device.   Remember, even in full screen mode it still is running in an 'application window' not on the hardware itself.

Related, but different - gamma control inside older games (like dragon age origins) doesn't work for similar reasons.

[Lovetta65]

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@fuvimos myLoyola Sign In wrote:

Hello everyone,

when I try to change the brightness of the monitor (27 inch 5k iMac, 2020 model) within the guest OS (Linux Mint 21, Cinnamon), nothing happens. Is this maybe a limitation of VMWare Fusion (12.2.4) or type 2 hypervisors in general?

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I appreciate the information and advice you have shared. I will try to figure it out for more.

[fuvimos]

Thank you for your replies! That makes sense and now I can stop trying to get brightness adjustment working in the VM. I will instead change the brightness through the host, by pressing the respective function keys on the keyboard.