Linux-libre
Linux-libre is a modified version of the Linux kernel that contains no binary blobs, obfuscated code, or code released under proprietary licenses. Binary blobs are software components with no available source code. In the Linux kernel, they are mostly used for proprietary firmware images. While generally redistributable, binary blobs do not give the user the freedom to audit, modify, or, consequently, redistribute their modified versions. The GNU Project keeps Linux-libre in synchronization with the mainline Linux kernel.

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 (FSFLA), then endorsed by the Free Software Foundation (FSF) 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 (especially wireless) 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
 Dragora GNU/Linux-Libre
 dyne:bolic
 GNU Guix System
 Parabola GNU/Linux-libre

Considered small distributions
 libreCMC
 ProteanOS (If the underlying hardware is not supported, it must be ported.)

Historical

 Hyperbola GNU/Linux-libre
 Musix GNU+Linux

Distributions that compile a free Linux kernel
These distros do not use the packaged Linux-libre but instead completely remove binary blobs from the mainline Linux kernel, to make Linux-libre. The source is then compiled and the resulting free Linux kernel is used by default in these systems:
 Debian
PureOS
 Trisquel (The Linux-libre deblob script is used during its development).
Uruk GNU/Linux
 Ututo

Historical

 BLAG
gNewSense (It was based on Debian.)
Canaima (It was based on Debian.)

Linux-libre as an alternative kernel
Distributions in which Linux is the default kernel used and which propose Linux-libre as an alternative kernel:
 Arch Linux
 Fedora
 Gentoo Linux
 Mandriva-derived (PCLinuxOS, Mageia, OpenMandrivaLx, ROSA Fresh)
 openSUSE Tumbleweed (via OpenBuildService)
 Slackware

See also 

 GNU Hurd, an operating system kernel developed by GNU, which follows the microkernel paradigm
 Libreboot
 LibrePlanet
 List of computing mascots
 Open-source hardware
 :Category:Computing mascots

References

External links 

 

2008 software
Free software programmed in C
GNU Project software
Linux kernel
Operating system kernels