Apple MacBok’s secret EFI magic to enable iGPU!
Since some years I have a Apple 15″ Retina MacBook Pro that I mostly used with macOS. But as that becomes buggery and slower with each release I started to migrated back to my t2sde as primary desktop. One thing I noticed last year already, is that the EFI BIOS is switching off the Intel iGPU when booting anything else than macOS. A special and secret EFI protocol is required to authenticate as macOS and being worthy to leave the integrated graphics switched on. As this year it again did not work anymore, and it took a whole afternoon to find out, I made a short video covering the details:
Turned out, an EFI firmware update changed the protocol return value, so that the previous code would not call both protocol functions anymore, sigh!
If that is the new state of apple hardware and firmware design you probably want to thin twice if you want to get one, especially if you ever may want to run anything beside macOS, … :-/
