Funny coincidence! I added w520 support to coreboot as a weekend project several years ago! It should still work great on your w520, except there were several

Funny coincidence! I added w520 support to coreboot as a weekend project several years ago! It should still work great on your w520, except there were several power management issues related to the optimus GPU I just couldn't fix. Oh and careful with the RAM if you use 32G as some brands will not work well, because of raminit issue (I haven't followed, maybe they are fixed now)