Purism, following its strict philosophy, uses and installs completely Free software, meaning there is no mystery software running anywhere within the kernel, the operating system, nor any software applications. To elaborate on what the means, and why the “Librem” the first laptop line shipping with completely Free software, let’s deconstruct a computer into its main parts where software is required.
Purism’s software stack: Software Freedom Visualized
How do these collections of software interact with each other?
Here’s what happens, in sequence, when you switch on your computer:
- All hardware components spin up, and load the firmware they have burned onto them, such as the hard drive or solid state drive.
- The BIOS then loads firmware for additional components, be that the memory controller, system management controller, embedded controller, USB, and/or GPU.
- At this point, the BIOS hands off to a boot loader. Purism uses GRUB, which is a completely Free boot loader. A boot loader is the first software program that runs when a computer starts. It is responsible for loading and transferring control to the operating system kernel software. Purism uses a completely Free version of Linux as its kernel.
- The Linux kernel, in turn, initializes the rest of the operating system and manages most of the interaction between software and hardware while the operating system/platform (GNU) is running.
Purism uses a completely Free version of GNU. GNU allows for thousands of free software applications to run on top of it, and the “distribution” that Purism provides with its computers to bundle purely Free Software applications is PureOS. Hence, PureOS is a “GNU/Linux” (or “GNU+Linux”) software distribution (or operating system, depending on your perspective).
Aiming for the Final Frontier
As you can see with the diagram above, computers made by Purism have 99.9% of their hardware+software stack freed. We, of course, want to reach 100.0%, and the remaining parts (the BIOS and components’ embedded firmware) are the final frontier, the “peak of the Everest”, the most difficult obstacle to overcome. You can read more about that effort in the advanced topics of the “Why Purism?” section or help us out now.