XtratuM/NG (XNG) in SAFEST
XtratuM-Next Generation (XNG) is a Type I hypervisor designed to achieve temporal and spatial isolation of safety critical applications sharing a common hardware execution platform by means of the use of hardware virtualization technologies. XNG provides the services needed by safety-critical systems such as partition management, support for system and non-system partitions, resource virtualization, temporal partitioning based on a cyclic scheduling policy, spatial partitioning using the hardware mechanisms for memory protection, inter-partition communication through sampling and queuing ARINC-653-like ports, and a health monitoring service which detects failures and implements mechanisms for fault containment. Additionally, XNG is ready to host third-party operating systems such as RTEMS.
XNG plays a key role in the SAFEST project: it envisions, among other objectives, the implementation of an Autonomous Flight Termination Unit (AFTU) based on the hardware-independent, multi-layered SMart Integrated Avionics (MIA) software architecture. MIA’s SW architecture includes the XNG hypervisor, which provides virtualisation features and isolates the upper software layers from direct calls to the hardware. Therefore, XNG, besides providing virtualisation features, acts as hardware abstraction layer for the rest of the SW architecture.
After XNG’s adaptation to the hardware platform and the development of a RTEMS support layer to the hypervisor, XNG-based RTEMS partitions isolated from each other will be able to be deployed in the same hardware. Eventually, the different SW/HW components of the MIA architecture and the AFTU application will be integrated and the deployment of the binaries on the target platform will be carried out.
In addition, parallel efforts conducted by fentISS in the framework of other projects like HERMES will allow XNG to be ported to additional hardware platforms such as the NG-ULTRA. The combination of the hardware independence provided by the MIA architecture and building the avionics platform over XNG will allow the migration of the entire software architecture to new platforms as soon as they become supported by XNG, thus enforcing the principles of flexibility, modularity and reduced costs.
