A Brief Overview of the Linux Source Tree

Several source code directories will be especially important in this course. We encourage you to take a look around!

The kernel directory contains source code for core kernel subsystems. For example, later in the semester we will be talking about the kernel scheduler code that can be found under the kernel/sched/ directory, and much sooner than that we will use libraries that invoke the kernel's process fork code that is implemented in the kernel/fork.c file.

The include directory contains most kernel header files. Many of the significant kernel header files (which we will use later in the semester to implement kernel modules) are found under the include/linux directory. These kernel header files are different from the header files found under include/uapi/linux that Linux exports to userspace (which we will use from early on in the semester to implement user space programs).

The arch directory contains core architecture dependent code. For example, all x86 specific code is found under the arch/x86/ directory. The Raspberry Pi (version 3 and later) has an ARM processor architecture, so for this course we're only really interested in the code found under arch/arm. Underneath each architecture specific directory you'll find a directory structure that is very similar to the root linux source directory. For example, the arch/arm/kernel directory contains ARM architecture specific support for core kernel subsystems, and the arch/arm/include directory contains ARM-architecture dependent header files.