GoKawiilHave you ever wondered what really happens between the moment you press the power button and the moment your login screen shows up? That gap—usually some seconds—hides one of the most intricate initialization sequences in computing. Today I want to walk you through it.
This is the first article in a series where I’ll try to make sense of the Linux kernel internals together with you. We’ll talk about how Linux boots, how it manages processes and memory, how it deals with hardware, and so on. If you’ve ever been curious about what’s happening under the hood, you’re in the right place.
⚠️ Quick disclaimer I’m not a kernel expert—I’m learning out loud. The goal here isn’t a deep, exhaustive tour but a useful map: what the main pieces are and how they fit together. For the deep dives, the source is the real teacher. This article focuses on x86_64. The big picture applies broadly, but specifics vary on ARM, RISC-V, etc.
Now let me throw a metaphor at you, because this is going to be a long ride and we’ll need a thread to hold onto.
Imagine We’re Setting Up a Space Colony
Picture a barren planet. No air to breathe, no roads, no buildings, no power, no comms. We send a small advance team in a dropship. Their mission: turn this rock into a working colony, and do it before life support runs out.
The advance team can’t just unload everyone and start hosting town hall meetings. They have to do things in a very specific order. First the basics: confirm the lander didn’t crash, set up emergency procedures in case anything goes wrong. Then map the terrain, find usable resources, set aside areas for storage. Then bring up the construction equipment, build the first habitats, the power grid, the comms tower. Then start the proper governance: a colonial governor, a dispatch office that handles future crew arrivals, and a maintenance crew that takes over the boring “keep things running” duties. Finally, they wake up the rest of the colonists from cryosleep and hand them the keys to the place.
That’s pretty much what the Linux kernel does at boot. The bootloader is the dropship. Your computer is the barren planet. The advance team is the execution of the startup code in the Linux kernel—the one we’ll be following the whole time. And by the end of this article, that advance team will literally have transformed itself into the standby maintenance crew while a brand-new civilian government takes over. Bear with me—it’ll make sense as we go.
Here’s the rough trip we’re about to take:
Let’s start where the bootloader leaves off.
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