Alexander van der Grinten

In this talk, we explore the design of Managarm's microkernel. Managarm is a pragmatic microkernel-based OS with a focus on asynchronous operations. The talk covers various aspects of the microkernel, such as its IPC model, resource management, and user space API. Managarm's microkernel employs a capability-based design to manage hardware resources. In contrast to current mainstream OSes, Managarm's system calls never block but report completion asynchronously whenever possible. This includes system calls for common tasks such as memory management or inter-process communication (IPC). A lock-free ring buffer is used to quickly deliver asynchronous completion notifications to user space. Managarm implements a POSIX subsystem to be able to run various well-known UNIX applications (e.g., a Wayland desktop) on top of the microkernel. This subsystem is implemented entirely in user space. The kernel uses various acceleration strategies to to efficiently support this use case.