Open Source Summit Europe 2022

The boot process is probably the most overrated and at the same time neglected stage of running a computer. Why is that? Once one starts to think about it, it becomes obvious. A computer that is booting does not yet do anything perceived as valuable. The user who just turned it on wants to start using it as quickly as possible, and not be kept waiting. So the duration of the boot process as a whole often gets high attention. Beyond that, almost nobody cares about what happens as long as the boot finishes successfully. So for those of us who wish to understand the booting process, it is often complicated to see the actual concepts and reasons behind them. In this presentation we will look at common boot strategies found on the ARM and RISC-V instruction set architectures, and examine why and how they relate to specific hardware configurations. The various concepts such as a secondary program loader, boot source orders and suitable storage technologies will be discussed and put into context, to serve as the groundwork for a proper understanding of the topic. At all stages, we will focus on providing a beginner-friendly representation, instead of diving into advanced specifics such as boot time reduction.