Unable to disable discrete GPU and boot Big Sur

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I have a new Big Sur 11.1 Open Core build with everything working.

- ASROCK Z390 Phantom Gaming-ITX/ac (Bios is v4+)
- Big Sur 11.1
- i5-9600k
- RX 5700

Currently running the RX 5700 and looking to upgrade to (surprise) a 3080 for gaming in my dual boot. I know this isn't supported, but I'm trying to test out disabling discrete graphics and using Intel graphics before I shell out the cash.

I've tried -wegnoegpu and the "DeviceProperties" method. Both methods fail on boot with some funky screen. I can't see the verbose logging because the screen gets scrambled (is there a way to get the kernel panic logs otherwise?). My Bios is set so that integrated graphics is the primary output.

I can try the SSDT method, but I've also seen people mention that you might have to install Big Sur with the graphics card physically removed from the system. This sounds like quite a bit of work so wanted to check here on options first. Is it possible that since I installed Big Sur with the 5700 attached that my integrated graphics aren't properly configured?

 

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Adding config.plist

 

[kdolaac]

did you try removing that card and boot

 

[accord2]

I did try this, and get a failed boot as well. At this point, I'm just looking for the right approach.

Should I go through framebuffer patching tutorials? Has anyone successfully got Big Sur to boot on iGPU while a dGPU is attached and enabled in BIOS?

 

[Hooner]

I'm in the same situation, but with two Nvidia GPUs: one supported and the other is not in Big Sur. Have you had any success?