Linux and the 2012 Macbook Pro Dual GPU Saga

[comda]

Greetings! Long time!

Been running linux a lot lately and decided to try it on the macbook pro. Issue is. No matter what distro im using its selecting to run the Nvidia GPU and as a result its hot, and battery really takes a hit. Within PopOS there was a selector for the GPU's but selecting the Intel card and the machine would simply boot to a cursor. Nothing more.

Linux mint and Fedora (my ideal choice) both show both the Graphics cards, but im unsure how to default the machine to use the Intel HD 4000 or at least have a GPU switcher. shockingly everything nearly works. Wifi i got to work but otherwise alls great. Very snappy.

I am running OSX as well, but I've got the dual SSD mod on this 9,1. Anyone know how to add a proper GPU switcher, ensure drivers work etc?

Ive done Lspci | preg VGA to ensure the OS is seeing both GPU's and that appears to be the case.

Thanks in Advanced.

2012 Macbook Pro
2.7Ghz intel i7 3rd gen
16gb Ram
Dual SSD
running Catalina and currently Linux Mint, but would like Fedora.
Nvidia 650M 1gb + Intel HD 4000.

 

[Draeconis]

So, apologies for the half-answer, but what you're after is something similar to this;

765954 – EFI boot failure to properly initialize graphics on Macs with Intel and AMD graphics (MacBookPro 8,2 and 8,3

bugzilla.redhat.com

As a MBP Late 2011 owner, you have to make changes to the grub boot config file, in order to power off the discreet GPU, on some very specific lines;

outb 0x728 1 outb 0x710 2 outb 0x740 2 outb 0x750 0

Again, these are specific references for my model, so they likely wouldn't work for you. The MacBook Pro also has an NVRAM setting disabling the GPU, as it's not 100%;

nvram fa4ce28d-b62f-4c99-9cc3-6815686e30f9:gpu-power-prefs=%01%00%00%00

You'd need to search around for the correct code(s) to set via outb, as well as experiment with the above nvram command in recoveryOS to see if this also disabled your GPU.

further; specific to Fedora (which I use as well) you'll want to look at /etc/grub.d/00_header, as it's named differently, and when you want to implement the changes you've made (assuming you've installed it letting Fedora partition the disk for you), the command on Fedora would be;

sudo grub2-mkconfig -o /boot/efi/EFI/fedora/grub.cfg

Please note; every time there is a grub update, you'll need to re-apply the settings you've added to /etc/grub.d/00_header using the above command, or the EFI boot process will complain about missing 'outb' references, and the dGPU will spin up