Hey guys. I just had a chance to take a look quickly at the M1 GPU driver. At the first glance, dithering can also be controlled by the NVRAM variable. In the case of M1 chipset and its driver, this parameter is "enableDither". So, to disable dithering on M1 devices, open the terminal in normal mode (NVRAM variables are controlled from the normal mode on M1 devices) and enter the command sudo nvram boot-args="enableDither=0 PE_i_can_has_debugger=1 iomfb_RuntimeProperty_enableDither=0" and type your password. To verify the command was accepted, use the command: log show --process 0 | grep "Dither" The expected output is: xxxx-xx-xx xx:xx:xx 0x180b Default 0x0 0 0 kernel: (Sandbox) System Policy: nvram(831) allow boot-arg-set enableDither I am not sure this will help as most of M1 devices have pretty low frequency PWM. But some devices, like MacBook AIR 2022 has no PWM. It would be nice to get your feedback. Just type what exactly device you use and your feeling… Update1: the command was extended to sudo nvram boot-args="enableDither=0 PE_i_can_has_debugger=1 iomfb_RuntimeProperty_enableDither=0" Update2: macOS Ventura has redesigned approach of using kernel extensions. More likely, this solution doesn’t work there. So try it on all earlier macOS versions.

I get Error setting variable - 'boot-args': (iokit/common) not permitted.

mirza Did you try in normal or recovery mode?

Both I get same error, in normal and recovery mode…

mirza and you used it with sudo? If yes, please enter in recovery mode, open the terminal there and disable the SIP by the command “csrutil disable” Then enter the normal mode and try again to set the nvram parameter.

mirza BTW, what device you use? I tried it on MacBook Pro M1 2020.

NewDwarf Yes, MacBook Air M1 2020 here too. I think I managed to do it now, here is when I tap log show command: 2022-11-18 20:26:09.371933+0100 0x1f7ba Error 0x0 0 0 kernel: (Sandbox) System Policy: nvram(3532) deny(1) boot-arg-set enableDither 2022-11-18 20:28:15.041513+0100 0x1fba6 Error 0x0 0 0 kernel: (Sandbox) System Policy: nvram(3561) deny(1) boot-arg-set enableDither 2022-11-18 20:30:26.325331+0100 0x1ff72 Error 0x0 0 0 kernel: (Sandbox) System Policy: nvram(3592) deny(1) boot-arg-set enableDither 2022-11-18 20:35:55.447516+0100 0x1797 Error 0x0 0 0 kernel: (Sandbox) System Policy: nvram(791) deny(1) boot-arg-set enableDither 2022-11-18 20:37:44.060383+0100 0x1678 Error 0x0 0 0 kernel: (Sandbox) System Policy: nvram(703) deny(1) boot-arg-set enableDither 2022-11-18 21:43:40.607977+0100 0x250e Default 0x0 0 0 kernel: (Sandbox) System Policy: nvram(1290) allow boot-arg-set enableDither 2022-11-18 21:43:40.607984+0100 0x250e Default 0x0 0 0 kernel: [System Event] [9361451525] [INFO] [Subsystem: nvram] [Event: write] boot-args to enableDither=0 2022-11-18 21:48:05.225821+0100 0x3bd9 Default 0x0 0 0 kernel: (Sandbox) System Policy: nvram(1672) allow boot-arg-set enableDither 2022-11-18 21:48:05.225835+0100 0x3bd9 Default 0x0 0 0 kernel: [System Event] [15712279907] [INFO] [Subsystem: nvram] [Event: write] boot-args to enableDither=0

mirza thanks. Do you feel any effect of this command?

NewDwarf Difficult to say right away, I will test it and let you know. Thanks a lot.. Do you feel any difference?

mirza I sit about 10 minutes after entering this command. Currently, I don't have this laptop on the hand and I can check only on Monday. As my laptop has PWM, I can still have side effect of PWM. It would be nice if one who have MacBook Air 2022 check this command as according to reports it is PWM free.

It's probably placebo, but I have a feeling it's better. We'll see.

Disable dithering on M1/M2 devices

mirza

https://www.dropbox.com/s/pb7adstp5jnudmw/kextstat.rtf?dl=0

NewDwarf

mirza BTW, do you use macOS Ventura?

NewDwarf

mirza If you really use macOS ventura, it explains the weird things I noticed (you don't have any mentions of 'IOMobileFramebufferLegacy' in the kernel log).

The macOS Ventura changed concept of using of the kernel extensions. I don't familiar with the technical details.

The folder you dropped just doesn't have the drivers which existed on the previous macOS versions.

mirza

Which OS should I install? I will try to revert to older one.

NewDwarf

mirza Previous macOS version should be fine.

It is macOS Monterey.

ryans

NewDwarf do you think it will be possible to disable dithering on Ventura?

mirza

NewDwarf - Installation is finishing now. What command should I enter in terminal?

mirza

ok I will do it now.

NewDwarf

ryans Yes, I think it will be possible. But to find the solution, we have to use the Monetey and earlier macOS versions as macOS Ventura has kind of monolithic kernel.

NewDwarf

mirza I guess the already entered commands are still active. You can verify it by the "nvram -p | grep boot-args" command.

If it will return the parameters you passed to the command, please, run the

log show --process 0 | grep "IOMobileFramebufferLegacy"

command.

Also, please do zipping of the /System/Library/Extensions folder and share it.

CRoebuck

NewDwarf Update2: macOS Ventura has redesigned approach of using kernel extensions. More likely, this solution doesn’t work there. So try it on all earlier macOS versions.

Presume that's product wide inc. Intel and not just limited to Mx. Boot args fix been working for me on a 2020 i5 4TB

NewDwarf

CRoebuck thanks. This is important information which means that the kexts are part of a kernel like the iOS kernel.

mirza

NewDwarf

https://www.dropbox.com/s/5117eizi36fc6pp/kext.zip?dl=0

Reminder, now I'm on macOS Monterey

dirtydenim

NewDwarf

I've got an M2 Macbook air coming today- let me know what you need to help with testing. Assume it will come out of the box with Monterey, I will hold off upgrading til there is a solution.

Just out of curiosity, do we have a solution for setting lower color depth? This is something that has helped me in the past. On windows laptops, easily accessed through integrated graphics settings. 6 bit is also very easy to determine dithering vs. no dithering using test patterns.

MAS-76

dirtydenim yes please! Would be incredible if this solution actually works for eye strain

NewDwarf

dirtydenim Could you please check the results of the command

sudo nvram boot-args="enableDither=0 PE_i_can_has_debugger=1 iomfb_RuntimeProperty_enableDither=0"

whether it will have any effect.

Also, it would be useful to see the output of the command

log show --process 0 | grep "IOMobileFramebufferLegacy"

dirtydenim

NewDwarf

To clarify- do you want me to run in normal desktop mode or recovery mode?

NewDwarf

dirtydenim On M1/M2 devices this command should be executed in normal mode only.

dirtydenim

I was able to successfully execute the command. I do not see any changes in my test image but sometimes it requires lowering the color depth as I mentioned to show the steps instead of a smooth gradient.

Note, I first had to use the "csrutil disable" command in recovery mode.

Difficult to tell if there is a comfort improvement yet, I will report back after some time and try some other objective tests- images, etc. to validate dithering is indeed disabled.

Also @NewDwarf there was no result from the log show --process 0 | grep "IOMobileFramebufferLegacy" command.

Is there a log I need to review?

NewDwarf

dirtydenim Thanks. If the log command returns nothing, this means this part of the driver is not used and the boot parameters we passed by the nvram command don’t work.

…it is sad, but it requires more effort by digging in other directions.

mirza

@NewDwarf - Make an app that disables this, and set price whatever you want, you have hundreds of customers who will buy it 100% 😃

NewDwarf

mirza BTW, I can see the output of log show --process 0 | grep "IOMobileFramebufferLegacy"

2022-11-21 0xbb Default 0x0 0 0 kernel: (IOMobileGraphicsFamily) virtual bool IOMobileFramebufferLegacy::start(IOService *)

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