How is the Linux kernel tested?

When we talk about something as big as the Linux operating system, one thing that also comes into my mind is how they make it work so effectively. Sure, it works like a charm, but how do they handle all the bugs and errors that can literally exist anywhere in the source code of the entire system

We know that we get a new Linux operating system every three months and in that period roughly two weeks are reserved for the “merge window”. This window is the time where all the code that has already been developed and approved will be merged in the Linux Torvalds tree which is the mainline. So, the time that is left is basically reserved for bug fixes and stabilization.

There are plenty of developers that work on the project release and maintenance and making sure that the linux kernel remains as bug free as possible. But it should also be noted that they not only depend on the experience and knowledge of the developer only to fix the bugs, they make use of different tools which range from automation testing, static analysis of code and more.

Let’s learn more about these tools to understand what they bring to the table for linux developers.

Continuous Integration

Kernel CI is one of the automated tools that is on the Linux kernel and it is a Linux Foundation project. Currently is one of the most complete automated testing and continuous integration tools for the Linux kernel.

LKFT (Linux Kernel Functional Testing) is another automation tool that is present on the linux kernel and is a continuous integration tool from Linaro that performs functional tests on several kernel development trees. It is mainly used to identify bugs and regressions.

Static Analysis of Code

Smatch, which is a static analysis tool that was developed with a focus on the Linux kernel. It enables the developers to identify programming errors like access to null pointers, buffer overflow, deadlocks, usage of uninitialized variables, and many more.

Sparse is also another tool on the Linux kernel that was originally written by Linus Torvalds and integrated with the Linux source code, designed to find possible coding faults in the kernel.

Automation tool testing

kselftest is another testing framework available in the Linux source code. It is capable of testing specific parts of the kernel. The tests are mainly written in C language or shell script.

The Linux Test Project (LTP) is also another project on the Linux kernel which offers a set of automated tests that validates not only the functionality of the Linux kernel but also the reliability, and stability of the operating system.