LinuxBoot: Linux as firmware
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Both the free-software and security communities have recently been focusing on the elements of our computers that run below the operating system. These proprietary firmware components are usually difficult or impossible to extend and it has long been suspected (and proven in several cases) that there are significant security concerns with them. The LinuxBoot Project is working to replace this complex, proprietary, and largely unknown firmware with a Linux kernel. That has the added benefit of replacing the existing drivers in the firmware with well-tested drivers from Linux.
To understand LinuxBoot and the problem it's working to solve, we first have to discuss how computers actually boot. We usually think of a running system as including the hardware, operating system (OS), and applications. However, for a number of reasons, there are several layers that run between the hardware and the OS. Most users are aware of UEFI (which replaced the older BIOS); for many systems, it prepares the system to run and loads the bootloader. These necessary functions are just the tip of the iceberg, though. Even after the computer finishes loading the OS, there are multiple embedded systems also running on the system entirely separate from the OS. Most notably, the Intel Management Engine (ME) runs a complete Minix operating system, while System Management Mode (SMM) is used to run code for certain events (e.g. laptop lid gets closed) in a way that is completely invisible to the running OS.
