Pre-boot patch to ignore non-metal GPU?

[pteeson]

My question:
Is there a way to to patch the Mojave pre-boot to leave my non-metal NVidia GT 120 GPU installed?

Why:
Mojave will not boot if it is installed even though I have an RX 570.
But I sometimes need to boot into an older version of macOS ( going back as far as Snow Leopard). As an example boot Mountain Lion and use Final Cut Express 4.0.1 to video edit some of my 700GB camcorder files.

At present I have to shutdown, re-install the GT 120, do the edit, shutdown, remove the GT 120 and boot back into Mojave.

Current version of Final Cut Pro reqires Catalina + $300. Not sure if I can install that without patching - which I have never ever needed up to now. And too epensive for my retement budget!

 

[joevt]

I suppose a boot loader like OpenCore could be made to change the GPUs vendor/product ID and class code.
I don't think OpenCore has many per OS settings, so you would need a different OpenCore for each each variation of settings that you want. This is where MyBootMgr would come in. https://forums.macrumors.com/threads/mybootmgr-refindplus-opencore.2231693/
It uses RefindPlus to choose an OpenCore.

As for how to change the vendor/product ID or class code, I'm not sure about that. I guess I would try device properties first. And if that doesn't work, then an SSDT patch.

Hopefully you won't need EFI code to remove stuff that the GT 120 PCI Option Rom adds during startup.

With OpenCore, you may include kexts WhateverGreen and Lilu. Maybe they have options for your situation. Kexts injected by OpenCore may load early enough to help your situation.
https://github.com/acidanthera/WhateverGreen
https://github.com/acidanthera/Lilu

 

[MarkC426]

Just get Davinci Resolve (free) and bin fce.
Even if there was a workaround, your mac could become very un-stable.

 

[saudor]

On hackintoshes, you can definitely use SDSTs to disable that nvidia using opencore. I reckon the same can be done for real macs too

 

[pteeson]

I suppose a boot loader like OpenCore could be made to change the GPUs vendor/product ID and class code.
I don't think OpenCore has many per OS settings, so you would need a different OpenCore for each each variation of settings that you want. This is where MyBootMgr would come in. https://forums.macrumors.com/threads/mybootmgr-refindplus-opencore.2231693/
It uses RefindPlus to choose an OpenCore.

As for how to change the vendor/product ID or class code, I'm not sure about that. I guess I would try device properties first. And if that doesn't work, then an SSDT patch.

Hopefully you won't need EFI code to remove stuff that the GT 120 PCI Option Rom adds during startup.

With OpenCore, you may include kexts WhateverGreen and Lilu. Maybe they have options for your situation. Kexts injected by OpenCore may load early enough to help your situation.
https://github.com/acidanthera/WhateverGreen
https://github.com/acidanthera/Lilu

Wow... Thanks for you time and reply.

Looks like there is a lot to read up on to make an informed deision. I did write a boot loader in my days working on 360/370 mainframes, not including micro code though (but code is code anyway).

But never needed to for Mac's (so far). I'll Google for some Intro docs about EFI and micro code.

I need to understand what I'm getting into before jumping on the bandwagon.

respects....

 

[pteeson]

Just get Davinci Resolve (free) and bin fce.
Even if there was a workaround, your mac could become very un-stable.

Well that's another way. But looks as though that's a professional app and beyond my present needs.

iMovie though is not comfortable for me even though it's free.

 

[pteeson]

On hackintoshes, you can definitely use SDSTs to disable that nvidia using opencore. I reckon the same can be done for real macs too

Thanks for the suggestion but I hve a real Mac. Did you mean SSDT?

 

[joevt]

Thanks for the suggestion but I hve a real Mac. Did you mean SSDT?

Yes, an SSDT. It is one method of modifying properties of a device. The idea is to make a change so that macOS skips the device.

 

[saudor]

Thanks for the suggestion but I hve a real Mac. Did you mean SSDT?

Yeah sorry SSDT.
Have a look at this page: https://dortania.github.io/Getting-...disable.html#finding-the-acpi-path-of-the-gpu

You can use hackintool to find the location of your GT 120 while booted in mountain lion etc. However it will get a bit complicated since you would need to run the open core boot loader when booting into Mojave (by holding option key) with these options and either have no boot loader for SL/ML or another separate opencore boot loader on another physical disk for your older OS. However, Open core might have some settings to bind patches to specific OSes but I havent really looked into that bit too much

Another option is to virtualize SL/ML using something like VMware fusion and run them inside mojave. It will of course run slower because you won’t have graphics acceleration but those OSes are before macOS relied heavily on GPU performance so you might be ok.