Conceptual
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Compiling the Kernel and Rebuilding Quickly

Building a whole kernel compiles tens of thousands of files and can take from a few minutes to well over an hour depending on your machine and how many jobs you run in parallel. After the first build, the build system recompiles only what your change touched, which usually takes seconds. Knowing the difference between a cold build and an incremental one is the difference between a painful loop and a fast one. It also tells you when a slow rebuild means you accidentally changed something fundamental.

Questions this Concept answers

  • Why is the second build of a kernel tree usually far faster than the first?