Linux-libre


Linux-libre is an operating system kernel and a GNU package.
The GNU Project attempts to keep Linux-libre in synchronization with upstream development of the Linux kernel while removing any software that does not include its source code, has its source code obfuscated, or is released under a proprietary license.
Software components with no available source code are called binary blobs and, as such, are mostly used for proprietary firmware images in the Linux kernel. While generally redistributable, binary blobs do not give the user the freedom to audit, modify or, consequently, redistribute their modified versions.

History

The Linux kernel started to include binary blobs in 1996. The work to clear out the binary blobs began in 2006 with gNewSense's find-firmware and gen-kernel. This work was taken further by the BLAG Linux distribution in 2007 when deblob and Linux-libre was born.
Linux-libre was first released by the Free Software Foundation Latin America, then endorsed by the Free Software Foundation as a valuable component for the totally free Linux distributions. It became a GNU package in March 2012. Alexandre Oliva is the project maintainer.

Proprietary firmware removal

Methods

The removal process is achieved by using a script called deblob-main. This script is inspired by the one used for gNewSense. Jeff Moe made subsequent modifications to meet certain requirements for its use with the BLAG Linux and GNU distribution. There is another script called deblob-check, which is used to check if a kernel source file, a patch or a compressed sources file still contains software which is suspected of being proprietary.

Benefits

Aside from the primary intended effect of running a system with only free software, the practical consequences of removing device firmware that a user is not allowed to study or modify has both positive and negative effects.
Removal of device firmware can be considered an advantage for security and stability, when the firmware cannot be audited for bugs, for security problems, and for malicious operations such as backdoors), or when the firmware cannot be fixed by the Linux kernel maintainers themselves, even if they know of problems. It is possible for the entire system to be compromised by a malicious firmware, and without the ability to perform a security audit on manufacturer-provided firmware, even an innocent bug could undermine the safety of the running system.

Side effects

The downside of removing proprietary firmware from the kernel is that it will cause loss of functionality of certain hardware that does not have a free software replacement available. This affects certain sound, video, TV tuner, and network cards, as well as some other devices. When possible, free software replacement firmware is provided as a substitute, such as the openfwwf for b43, carl9170 and ath9k_htc wireless card drivers.

Availability

The source code and precompiled packages of the deblobbed Linux kernel are available directly from the distributions which use the Linux-libre scripts. Freed-ora is a subproject which prepares and maintains RPM packages based on Fedora. There are also precompiled packages for Debian and derived distributions such as Ubuntu.

Distributions

Distributions in which Linux-libre is the default kernel

Historical
These distros don't use the packaged Linux-libre but instead completely deblob the proprietary Linux kernel with some of the tools to make Linux-libre. The source is then compiled and the resulting free Linux kernel is used by default in these systems:
Historical
Distributions in which Linux is the default kernel used and which propose Linux-libre as an alternative kernel: