disable efficient-cores or performance-cores

[baptx]

The problem you're addressing (if any)

For people who use the 12th generation (or greater) of Intel Core processors, they may want to disable efficient-cores in the BIOS to improve performance (https://www.reddit.com/r/intel/comments/thp7jh/disabling_the_efficiency_cores_to_get_performance/).
Some people may also want to disable performance-cores instead to save more battery (https://www.reddit.com/r/overclocking/comments/x0xu1c/can_you_disable_performance_cores_to_force_an/).

Describe the solution you'd like

A BIOS option to disable efficient-cores or performance-cores.

Where is the value to a user, and who might that user be?

This could improve performance or save more battery for users of the laptop I am using (NovaCustom NV41 Series) and maybe other laptops using Dasharo / coreboot.

Describe alternatives you've considered

I also saw another way to disable efficient or performance cores without needing to reboot, using taskset but I did not try it yet:
https://unix.stackexchange.com/questions/686459/disable-intel-alder-lake-efficiency-cores-on-linux
The option in the BIOS could still be useful to have a default configuration.

Additional context

Issue originally reported in March 2023 on https://mail.coreboot.org/hyperkitty/list/[email protected]/thread/7G4K2OSB2VO3KCOV6265FHP2UXFT6IZT/#WSAUSGDVX4BAOZ3VTKUEW2VUGCUXZ7KF but it is still a work in progress according to https://review.coreboot.org/c/coreboot/+/73790.
I create the issue here also so we can track it on GitHub to have more visibility.

[macpijan]

Something like this: https://docs.dasharo.com/dasharo-menu-docs/dasharo-system-features/#cpu-configuration ?

This is already implemented for MSI desktop boards, and works fine.

[macpijan]

@wessel-novacustom Is it interesting for laptops as well?

@mkopec do you see any showstoppers here?

[wessel-novacustom]

@wessel-novacustom Is it interesting for laptops as well?

Let's trace popularity here first.

[mkopec]

@mkopec do you see any showstoppers here?

For Alder Lake I don't, it should work the same way as on desktop ADL. For Meteor Lake, I'm not so sure, since it has P, E and LP-E cores now, so we'd probably need to add another core type.

[miczyg1]

@mkopec do you see any showstoppers here?

For Alder Lake I don't, it should work the same way as on desktop ADL. For Meteor Lake, I'm not so sure, since it has P, E and LP-E cores now, so we'd probably need to add another core type.

Core disabling will need an extension for MTL SKUs (a proper truth table with core counts and another menu entry for LPE core)

[baptx]

@wessel-novacustom Is it interesting for laptops as well?

Let's trace popularity here first.

It looks like someone already requested it on #973 but I think it does not matter if we use a desktop or laptop, it is interesting for both. Disabling performance-cores on a laptop would be even more useful than a desktop to save battery.