Back in the day, rebuilding the kernel was something of a rite of passage for most Linux users. Typically, a Linux distribution would use a plain kernel that wasn't optimized for any specific CPU type and was bundled in various bits and bobs that users might need. Many other features and drivers – especially experimental ones – were left out, though. I remember having to recompile my kernel just to get audio working on my old Cyrix M3 box running Red Hat 5.1 back in the late 1990s.

Today, many desktop Linux distros include multiple kernel packages built for different CPU types, and almost every feature and driver is available as a module. Very few users actually need to build a custom kernel by hand, so why do it? Well, it's still a very useful technique to learn. Even the most bleeding-edge distros don't always enable every single feature in the kernel, and what if a new kernel is released with an important fix or update you need? You could wait a few weeks or months for your distro to package it up, but if you know how to compile it yourself, you can stay ahead of the game.

Some patches that you might want to try aren't part of the main Linux kernel source code tree, so you have to compile your own kernel to use them. Aside from all of the practical benefits, it's just fascinating to see what's going on inside the guts of a Linux installation and is a good little project to take on if you have a few spare hours on a weekend. Over the next few pages, I'll show you how to get, configure, compile, and install a fresh new kernel directly from Linus Torvalds' computer (well, thereabouts) and show you how to apply patches as well.

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