Pure software virtualisation is an option but would use up too much graphics performance. And you can never have enough of that. In addition, this option does not include real memory protection. This is why Renesas worked with Imagination Technologies to develop and implement a new GPU hardware virtualisation concept. This provides the various programs with up to eight virtual GPUs. They are entirely hardware-managed once the central operating system has defined the resource distribution and prioritisation.
This approach has a whole string of benefits. First, it barely causes any reduction in performance compared to a non-virtualised system. Second, each process can be aborted independently, without affecting the others. This independence enables guaranteed performance allocation, so that an instrument cluster will always be able to display its content under all circumstances. It would even be able to do this if, for example, the infotainment system’s web browser froze and had to be restarted. Third, the GPU can also detect and stop malicious or faulty software after a certain delay – this could include so-called shader bombs that can use 100% of the GPU’s capacity. And finally, each virtualised software program uses its own graphics driver that is not dependent on a particular operating system (Fig. 3). Every supplier of virtualised control device software can choose the appropriate operating system for their application, such as open-source Linux for the infotainment system and an ISO26262-certified OS for the security-critical applications.
In this type of system, hardware resource management and security feature configuration is carried out by the hypervisor, a sort of simple operating system with the highest level of access rights. There are various types on the market, each with its own advantages. Renesas supports its partners by helping them port their hypervisors to the R-Car, enabling customers to choose their preferred solution.