IO Virtualisation in a Partitioned System

Partitioned systems permit to isolate in partitions several applications with different security levels and/or crit-icality. Hypervisor technology provides virtual machines to execute partitions under two basic principles: space and time isolation. This view is complemented with the "dedicated devices" technique that assigns devices exclusively to a partition. However in case of shared devices a partition has to provide a device or IO virtualisation to the other partitions, referred as the "I/O Server" approach. We present a solution for device virtualisation on the XtratuM hypervisor which has been specifically designed for critical embedded systems. The approach is in the scope of the Open Secure Vehicular Platform project. Such system will support different types of partitions, from real time constrained to non-trusted user partitions running general purpose operating systems.