System76, one of the few Linux-centric OEMs, has started to offer coreboot on some of their systems.
Apparently, the new System76 firmware includes a new ACPI table, though I can’t seem to find that table documented on the ACPI spec list (which appears to have been last updated Summer of 2019).
Add System76 ACPI driver, which adds support for Fn-Fx key combinations, keyboard backlight, and airplane mode LEDs on System76 laptops running open source firmware.
https://github.com/pop-os/system76-acpi-dkms
https://patchwork.kernel.org/patch/11180033/
https://lkml.org/lkml/2019/10/8/851
Firmware Security 