# Concepts

This chapter describes various concepts which are used in the Linux kernel.

* [Per-CPU variables](/linux-insides/summary/concepts/linux-cpu-1.md)
* [CPU masks](/linux-insides/summary/concepts/linux-cpu-2.md)
* [The initcall mechanism](/linux-insides/summary/concepts/linux-cpu-3.md)
* [Notification Chains](/linux-insides/summary/concepts/linux-cpu-4.md)


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