Flexible device pass-through solution for embedded systems

Virtualization is a technology that allows to partition or share computer hardware resources into an isolated execution environment (EE), also known as Virtual Machine (VM). In each VM, a guest OS and, on top of it, applications are running without knowing that they are enclosed in a virtualized environment. Every VM is independent, meaning that each one of them can not interfere with another VM or with the underlying host. Unfortunately, virtualization introduces overhead in the system which, especially when it comes to device virtualization or emulation, can be overcome or mitigated by using state-of-the-art technologies like device pass-through. This technology is proven to deliver almost native performance. As of today, there are both open and closed implementations of this technology, which are either hardly accessible or do not offer a flawless experience. This thesis analyzes a new virtualization solution, proposed by Virtual Open Systems, called VOSySzator. VOSySzator is an emulator and virtualizer which will provide the user with a flexible solution to perform device pass-through. Thanks to VOSySzator’s design, the user will be able to selectively pass-through devices with ease, with VOSySzator taking care of all the complications deriving from using this technology. To make the device pass-through as smooth as possible, VOSySzator will automatically resolve all the dependencies of the device being passed-through. Depending on the type of device, this can vary from being a simple operation to an intricate puzzle of dependencies and constraints that must be all met for the pass-through to work as expected. The core part of this thesis concerns this last point: being able to identify, represent, and satisfy these dependencies, extracting all the relevant pieces of information from the device tree of the host OS. As the last challenge, this work required also designing and implementing the tools to properly craft the guest device tree nodes to properly expose the passed-through device and connected dependencies to the guest OS. The results obtained from this paper concern the implementation of these functions, which is the key to having a highly-optimised and hassle-free pass-through experience.