14^th Real Time Linux Workshop, October 18 to 20, 2012 at the Department of Computer Science, University of North Carolina at Chapel Hill

Hijack^{COS}_{Linux}: Practical, Predictable, and Efficient OS Co-Location using Linux

Gabriel Parmer, The George Washington University
Qi Wang, The George Washington University
Jiguo Song, The George Washington University
Tareque Hossain, The George Washington University
Yang Yang Wu, The George Washington University

Three of Linux's greatest assets, especially in embedded systems, are its extensive corpus of device drivers, its hardware compatibility layer that spans many architectures and platforms, and the broad spectrum of applications ported to it. This paper details an OS design that enables the co-location of both the Linux kernel, and other real-time operating system kernels on the same processor. In executing other operating systems in this manner, they receive the advantage of Linux's assets, while also enabling the benefits of running other OSes with alternate structures and goals.

This paper specifically focuses on the design and implementation of the compatibility layer with Linux that enables the co-located OS to selectively use specific Linux functionalities. The technique does not require modifications to the Linux kernel, and supports co-located kernels that provide user-level execution. An emphasis is on maintaining native performance and predictability of all co-located OSes. We detail the use of this technique to co-locate with Linux the Composite component-based OS – a real-time OS with a very different design. In doing so, we discuss the points of friction where Composite is adapted to ensure system correctness, or to avoid sacrifices in performance or predictability. We provide an evaluation of the system with specific emphasis on different means for the co-located OS to access the device drivers and applications of Linux.