Open Source Summit + Embedded Linux Conference Europe 2020

The Linux kernel source has thousands of compile-time configurations that allow for an enormous number of variations of the kernel binary. This extreme configurability enables the same codebase to be used for everything from refrigerators to cars to supercomputers. But such configurability also brings unique challenges to development and maintenance. Unexpected combinations of configuration options can expose unknown security holes, the sheer number of kernel variations makes testing all impossible, and the languages used to implement configurability hinder source-code tools such as IDEs, bug-finders, and refactoring tools. This talk will go over the challenges of scaling to Linux's massive configuration system and my research on using program analysis techniques and automated tools to extract configuration constraints from Kconfig, Kbuild, and the C preprocessor. I will demonstrate a free and open-source tool, klocalizer, resulting from this research. Given source files, klocalizer generates valid Kconfig kernel configurations that include the given source. Finally, I will go over future work and potential applications to testing, bug-finding, and security.