The OpenBSD team works very hard to provide a high-quality kernel that requires no tweaking beyond setting the occasional sysctl or perhaps enabling a feature. But if you want to use an experimental feature or add a device driver to the kernel, or you want to squeeze OpenBSD into tiny hardware or embedded systems, you’ll need to build a custom kernel from source code. The OpenBSD people won’t support you if you venture into custom kernels, but they’ll provide you with everything you need to shoot yourself in the foot, as you’ll learn in this chapter.