5 How the Linux Kernel Boots

You now know the physical and logical structure of a Linux system, what the kernel is, and how to work with processes. This chapter will teach you how the kernel starts, or boots. In other words, you’ll learn how the kernel moves into memory and what it does up to the point where the first user process starts.

A simplified view of the boot process looks like this:

  1. The machine’s BIOS or boot firmware loads and runs a boot loader.
  2. The boot loader finds the kernel image on disk, loads it into memory, and starts it.
  3. The kernel initializes the devices and its drivers.
  4. The kernel mounts the root filesystem.

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