Big Sur: OpenCore underscore/black screen restart issue

[Silence720]

Hello - I recently upgraded to Big Sur and moved from Clover to OpenCore. I followed the OpenCore guide very closely and perfected my setup; however, I am running across an issue. My system will restart normally for the most part; however, every few times I get a black screen upon restart with an underscore. It will just hang until I completely power off and then on. I've tried a few things such as ProvideConsoleGop Quirk and to no avail can I get this issue to stop. Any suggestions?

 

[taiheng]

Same for me. I was tried changed hdmi cable to DP cable, change display out ports, changed monitor. All doesn't fixed the black/green screen & freeze issues.

Do you turn on Hidpi? My case is after I turned on Hidpi the black screen will happen frequently. It happen almost every boot up. So I decide to turn off Hidpi. But it still happen rarely.

 

[Silence720]

I tried using different cables etc and nothing works. My Hidpi is turned off. Let me know if you are able ti find a fix. I think it might have to do with my motherboard, but no issues occurred using Clover/Catalina. It all started when upgrading to Big Sur/Opencore.

 

[Bustycat]

Did your POST screen display any warning after that?

 

[Silence720]

No warning. Just a black screen and an underscore symbol in the top left corner.

 

[darkmacintosh79]

post your efi

 

[Bustycat]

A possible cause would be RTC. You could try to enable DisableRtcChecksum.

 

[Silence720]

A possible cause would be RTC. You could try to enable DisableRtcChecksum.

I already have it enabled.

 

[Silence720]

post your efi

My config files is attached. Thanks.

 

[Bustycat]

Not sure if it is related but DummyPowerManagement should be removed from the quirks section in your config.plist.

Your motherboard is Z370 so you don’t need SSDT-PMC.aml.