"The use of embedded systems is nowadays spreading at an increasing speed, to all aspects of modern life as well as all phases of industrial production. Their use extends from everyday non-critical or soft real-time consumer electronics and telecommunications equipment, to highly critical automotive, railway, automation control and aerospace systems, which satisfy the most stringent real-time constraints. Regardless of the application criticality, however, the need for high integrity and high availability systems as well as for systems that handle their data in a secure way is common and solutions demanding.In order to follow these technology tendencies, there is a growing interest in enabling multiple critical applications to share a single processor and memory with non-critical and of different security level ones.Partitioned software architectures seem to be the future of secure systems. They have evolved to fulfill security and highly critical real-time systems requirements where predictability is an extremely important factor.The significant technological know-how and the high cost required for using virtualization technologies has prevented European SMEs which develop embedded systems, from adopting these advanced technologies and exploiting the competitive advantages of the existing virtualization solutions and especially secure partitioning techniques in their systems.The VOS4ES goal is to provide a highly extendible, open source virtualization layer and a set of supporting tools that will allow SMEs to have access to virtualization technologies at a low cost and with high flexibility concerning its adaptation to specific requirements as opposed to existing proprietary solutions."