Imported from GitHub: Ausdauersportler/IMAC-EFI-BOOT-SCREEN · commit 944f12f · license GPL-3.0

Description

How to create an EFI boot screen vBIOS for Apple Late 2009 to Mid 2011 iMac systems using AMD MXM graphics cards

README

All vBIOS version stores here are based on the original PC card versions we found on the cards. The main adjustment was adding support for the internal eDP connected displays of iMac10,1 to iMac12,2.

Since a GOP BIOS does not support an EFI boot screen you need to install OpenCore via OCLP to get an emulated OpenCore boot picker.

Windows UEFI support via OCLP/OpenCore.