Linux as firmware.
The more things change, the more they stay the same. That may sound cliché, but it’s still as true for the firmware that boots your operating system as it was in 2001 when Linux Journal first published Eric Biederman’s “About LinuxBIOS“. LinuxBoot is the latest incarnation of an idea that has persisted for around two decades now: use Linux as your bootstrap.
On most systems, firmware exists to put the hardware in a state where an operating system can take over. In some cases, the firmware and OS are closely intertwined and may even be the same binary; however, Linux-based systems generally have a firmware component that initializes hardware before loading the Linux kernel itself. This may include initialization of DRAM, storage and networking interfaces, as well as performing security-related functions prior to starting Linux. To provide some perspective, this pre-Linux setup could be done in 100 or so instructions in 1999; now it’s more than a billion.
Read more at Linux Journal