Extensible kernels are leading OS researchers astray

We argue that ongoing research in extensible kernels largely fails to address the real challenges facing the OS community. Instead, these efforts have become entangled in trying to solve the safety problems that extensibility itself introduces into OS design. We propose a pragmatic approach to extensibility, where kernel extensions are used in experimental settings to evaluate and develop OS enhancements for demanding applications. Once developed and well understood, these enhancements are then migrated into the base operating system for production use. This approach obviates the need for guaranteeing safety of kernel extensions, allowing the OS research community to re-focus on the real challenges in OS design and implementation. To provide a concrete example of this approach, we analyze the techniques used in experimental HTTP servers to show how proper application design combined with generic enhancements to operating systems can provide the same benefits without requiring application-specific kernel extensions.