Unikraft - System calls implementation

Abstract

Unikernels are a recent virtualization solution providing lightweight, single-purpose virtual machines for the cloud with excellent performance in terms of throughput, memory consumption, boot time and a reduced attack surface, to name a few metrics. They leverage specialization and the use of minimalistic Operating Systems (OSes) to achieve these goals. However, their fundamental drawback is that they require applications to be manually ported to them, often requiring significant engineering work. Unikraft aims to solve these issues by providing a framework for building highly specialized and optimized unikernel images, where only the relevant components from the kernel and libraries are included.

With system calls, applications can invoke the different services provided by the OS. In a traditional OS these system calls are expensive, while with unikernels they are equivalent to regular function calls. Often, on a unikernel, these syscalls are not yet implemented and the applications might break without them. In this master thesis, system call kill to send any signal to a process and system call futex for fast users-space locking are ported to Unikraft. At the moment, there are over 146 syscalls implemented, which is already enough to run a rich set of mainstream applications, frameworks and languages.