Demo Abstract: Timing Aware Hardware Virtualization on the L4Re Microkernel Systems

Abstract

Hardware virtualization support has found its way into real-time and embedded systems. It is paramount for an efficient concurrent execution of multiple systems on a single platform, including commodity operating-systems and their applications. Isolation is a key feature for these systems, both in the spatial and temporal domain, as it allows for secure combinations of real-time and non real-time applications. For such requirements, microkernels are a perfect fit as they provide the foundation for building secure as well as real-time aware systems. Lately, microkernels learned to support hardware-provided virtualization features, morphing them into microhypervisors. In our demo, we show our open-source and commercially supported L4Re system running Linux and FreeRTOS side by side on a multi-core ARM platform. While for Linux we use the hardware features for virtualization, i.e., ARM's virtualized extension, we revert to paravirtualization for running the FreeRTOS guest. Paravirtualization adapts the guest kernel to run as a native application on the microkernel. For simple guests that do not use advanced hardware features such as virtual memory and multiple privilege levels, virtualization is simplified and the state of a virtual machine is significantly reduced, improving interrupt delivery and context switching latency. Both guests as well as the native application drive LEDs to exemplify steering actual devices as well as to show their liveliness. Taking down the Linux guest will not disturb the others.