Det finns huvudsakligen tre olika sätt att konstruera ett partitionerat system på: Federerad arkitektur, Integrerad Modulär Avionik (IMA) med ARINC 653 eller IMA med virtualisering. I den här rapporten undersöks de olika arkitekturernas egenskaper och vilka möjligheter som finns för certifiering av dem. Efter den teoretiska undersökningen har Virtualisering, och framförallt Xen, valts ut för en testimplementation och tillförlitlighetstester. Testimplementationen består av fyra partitioner där varje partition har sin specifika uppgift att lösa. Den fjärde partitionen används för att undersöka hur Xen hanterar en partition som aggressivt nyttjar I/O, processor eller arbetsminne. Testerna visar att Xen har en svag punkt: all I/O hanteras via en egen, speciell, partition. Denna partition saknar dessutom möjligheter att prioritera I/O från specifika partitioner. Den slutgiltiga slutsatsen av de tester som genomförts är att ett system byggt på Xen inte kan lämna samma tillförlitlighet som ett system med en federerad arkitektur eller ett system som bygger på ARINC 653. / One can basically take three different approaches when designing a partitioned avionic system: Federated Architecture, Integrated Modular Avionics (IMA) with ARINC 653 or IMA with Virtualization. This report examines the different architectural characteristics and the possibilities for certifying them. After the theoretical investigation, Virtualization and, in particular, Xen has been selected for a trial implementation and reliability tests. The implementation consists of four partitions where each partition has its own specific task to solve. The fourth partition is used to examine how Xen handles a partition that aggressively utilizes I/O, processor or memory resources. Tests show that Xen has a weak point: all I/O is handled through a separate and unique partition. This partition also lacks the ability of prioritizing I/O from specific partitions. The final conclusion of the tests carried out in this thesis is that a system built on Xen cannot provide the same reliability as a system with a federated architecture or a system based on ARINC 653.

<p>The Integrated Modular Avionics architecture , IMA, provides means for runningmultiple safety-critical applications on the same hardware. ARINC 653 is aspecification for this kind of architecture. It is a specification for space and timepartition in safety-critical real-time operating systems to ensure each application’sintegrity. This Master thesis describes how databases can be implementedand used in an ARINC 653 system. The addressed issues are interpartitioncommunication, deadlocks and database storage. Two alternative embeddeddatabases are integrated in an IMA system to be accessed from multiple clientsfrom different partitions. Performance benchmarking was used to study the differencesin terms of throughput, number of simultaneous clients, and scheduling.Databases implemented and benchmarked are SQLite and Raima. The studiesindicated a clear speed advantage in favor of SQLite, when Raima was integratedusing the ODBC interface. Both databases perform quite well and seem to begood enough for usage in embedded systems. However, since neither SQLiteor Raima have any real-time support, their usage in safety-critical systems arelimited. The testing was performed in a simulated environment which makesthe results somewhat unreliable. To validate the benchmark results, furtherstudies must be performed, preferably in a real target environment.The Integrated Modular Avionics architecture , IMA, provides means for runningmultiple safety-critical applications on the same hardware. ARINC 653 is aspecification for this kind of architecture. It is a specification for space and timepartition in safety-critical real-time operating systems to ensure each application’sintegrity. This Master thesis describes how databases can be implementedand used in an ARINC 653 system. The addressed issues are interpartitioncommunication, deadlocks and database storage. Two alternative embeddeddatabases are integrated in an IMA system to be accessed from multiple clientsfrom different partitions. Performance benchmarking was used to study the differencesin terms of throughput, number of simultaneous clients, and scheduling.Databases implemented and benchmarked are SQLite and Raima. The studiesindicated a clear speed advantage in favor of SQLite, when Raima was integratedusing the ODBC interface. Both databases perform quite well and seem to begood enough for usage in embedded systems. However, since neither SQLiteor Raima have any real-time support, their usage in safety-critical systems arelimited. The testing was performed in a simulated environment which makesthe results somewhat unreliable. To validate the benchmark results, furtherstudies must be performed, preferably in a real target environment.</p>

The Integrated Modular Avionics architecture , IMA, provides means for runningmultiple safety-critical applications on the same hardware. ARINC 653 is aspecification for this kind of architecture. It is a specification for space and timepartition in safety-critical real-time operating systems to ensure each application’sintegrity. This Master thesis describes how databases can be implementedand used in an ARINC 653 system. The addressed issues are interpartitioncommunication, deadlocks and database storage. Two alternative embeddeddatabases are integrated in an IMA system to be accessed from multiple clientsfrom different partitions. Performance benchmarking was used to study the differencesin terms of throughput, number of simultaneous clients, and scheduling.Databases implemented and benchmarked are SQLite and Raima. The studiesindicated a clear speed advantage in favor of SQLite, when Raima was integratedusing the ODBC interface. Both databases perform quite well and seem to begood enough for usage in embedded systems. However, since neither SQLiteor Raima have any real-time support, their usage in safety-critical systems arelimited. The testing was performed in a simulated environment which makesthe results somewhat unreliable. To validate the benchmark results, furtherstudies must be performed, preferably in a real target environment.The Integrated Modular Avionics architecture , IMA, provides means for runningmultiple safety-critical applications on the same hardware. ARINC 653 is aspecification for this kind of architecture. It is a specification for space and timepartition in safety-critical real-time operating systems to ensure each application’sintegrity. This Master thesis describes how databases can be implementedand used in an ARINC 653 system. The addressed issues are interpartitioncommunication, deadlocks and database storage. Two alternative embeddeddatabases are integrated in an IMA system to be accessed from multiple clientsfrom different partitions. Performance benchmarking was used to study the differencesin terms of throughput, number of simultaneous clients, and scheduling.Databases implemented and benchmarked are SQLite and Raima. The studiesindicated a clear speed advantage in favor of SQLite, when Raima was integratedusing the ODBC interface. Both databases perform quite well and seem to begood enough for usage in embedded systems. However, since neither SQLiteor Raima have any real-time support, their usage in safety-critical systems arelimited. The testing was performed in a simulated environment which makesthe results somewhat unreliable. To validate the benchmark results, furtherstudies must be performed, preferably in a real target environment.

Time management is one of the critical modules of safety-critical systems. Applications need strong assurance from the operating system that their hard real-time requirements are met. Partitioned system has recently evolved as a means to provide protection to safety critical applications running on an Avionics computer resource. Each partition has an application running strictly for a specified duration. These applications use the CPU on a cyclic basis. Applications running on a real-time systems request the service of time management in one way or the other. An application may request for a time-out while waiting for a resource, may voluntarily relinquish the CPU for some delay time or may have deadline before which it is expected to complete its tasks. These requests must be handled in a deterministic and accurate way with lower overheads. Time management within an operating system uses the hardware timers to service the time-out requests. The three well-known approaches for handling timer requests are tick-based, one-shot and firm timer. Traditionally tick-based has been the most popular approach that relies on periodic interrupt timer, although it has a poor accuracy. One-shot timer approach provides better accuracy as the timer interrupt can be generated exactly when required. Firm timers use soft timers in combination with one-shot timer wherein the expired timers are checked at strategic points in the kernel. The thesis compares the performance of these three approaches for partitioned systems and provides an insight about the suitability of the approaches. The thesis presents tick-based and one-shot timer algorithms that handle time-out requests of real-time applications running on a partitioned system by adhering to time partitioning rules. It compares the performance of these algorithms. It presents an one-shot timer algorithm named hierarchical multiple linked lists and the experimental results proves that the algorithm performs better than other conventional linked list based one-shot timer algorithms. The thesis also analyzes the timing behavior of real-time applications for partitioned systems. The hard real-time system under consideration is avionics system and an indigenously developed ARINC-653 compliant real-time operating system has been used to measure the performance.