Wikipedia
Libreboot (also known as GNU Libreboot) is a free software project aimed at replacing the proprietary BIOS firmware found in most computers with a libre, lightweight system designed to perform only the minimum number of tasks necessary to load and run a modern 32-bit or 64-bit operating system.
Libreboot was established as a distribution of coreboot without proprietary binary blobs. Libreboot is not a straight fork of coreboot; instead, it is a parallel effort that works closely with and re-bases every so often on the latest coreboot as the upstream supplier, with patches merged upstream whenever possible. In addition to removing proprietary software, libreboot also attempts to make coreboot easy to use by automating the build and installation processes.
The Libreboot project made possible the required modifications for completely libre variants of some ThinkPad, Chromebook, and MacBook laptops as well as desktop and server and workstation motherboards. According to its own documentation, it can work with any Linux distribution that uses kernel mode setting (KMS) for the graphics, while Windows is not supported and its use is discouraged by Libreboot.
The Free Software Foundation (FSF) endorses Libreboot, and it officially became part of the GNU Project on 14 May 2016.