Lenin Lemus

Non-intrusive Software-Implemented Fault Injection in Embedded Systems

Critical embedded systems, like those used in avionics or automotive, have strong dependability requirements and most of them must face with fault tolerance. One of the methods typically used to validate fault tolerance mechanisms is fault injection. The idea is to study the behavior of the system in presence of faults in order to determine whether the system behaves properly or not. Software-implemented fault injection (SWIFI) techniques enable fault injection to be performed by software. Although interesting, major drawbacks of existing SWIFI techniques are the temporal and the spatial overheads they induced in the systems under study. The reduction of these overheads is thus crucial, in order to be confident on the results and conclusions of a SWIFI experiment. This paper focuses on this problem. It proposes a new non-intrusive SWIFI technique for injecting faults in embedded (system-on-chip) applications. The technique exploits the features of a standard debugging interface for embedded systems, called Nexus, in order to inject faults without temporal overhead. Then, Nexus features are also exploited in order to observe, without spatial intrusion, the behavior of the target system in presence of the injected faults. In other words, the embedded system under study can be controlled (for injecting faults) and observed (for tracing its behavior) without customizing its original structure or altering its normal execution. Since based on Nexus, the technique has also the benefit of being applicable to any Nexus-compliant system. In order to illustrate the potentials of the approach, we use an automotive embedded control unit application as a case study. Some preliminary results obtained from the experiments performed are also discussed.

INERTE: integrated nexus-based real-time fault injection tool for embedded systems

Software implemented fault injection techniques (SWIFI) enable emulation of hardware and software faults. This emulation can be based on debugging mechanisms of general purpose processors [1] or in special debugging ports of embedded processors [2]. A well-known drawback of existing SWIFI tools rely on the temporal overhead introduced in the target system. This overhead is a problem when validating real-time systems. This paper presents a new SWIFI tool (INERTE) that solves this problem by using a standard debug interface called Nexus [3]. Using Nexus, system memory can be accessed at runtime without any intrusion in the target system. Thus, INERTE is able to inject transient faults without any temporal overhead.

Distributed industrial control systems: a fault-tolerant architecture

Abstract Nowadays, distributed architectures are the base of many manufacturing systems. Some aspects like fault-tolerance, system validation and design process are very important in the development of these systems. In this paper we study the dependability of three different architectures of a distributed system, and we show the development of both physical and logical fault injectors and the implementation of local performance monitors. We also study the impact of checkpointing mechanisms on the system performance in a control system based on a CAN network. Finally we propose a distributed system design methodology based on codesign.

Fast run-time reconfiguration for SEU injection

Mission critical systems are computer-based control systems that people depend on, often for their livelihoods, sometimes for their lives. As the integration scale of VLSI increases, computer-based systems are more prone to be affected by Single Event Upsets (SEUs). FPGAs have proven to be very useful devices for the injection of SEUs in order to assess the dependability of those systems. The conventional approach for injecting SEUs following the Run-Time Reconfiguration methodology involves reconfiguration times dependent on the complexity of the model. In case of complex models, it will greatly increase the execution time of fault injection experiments. This paper presents a new approach for the injection of SEUs into the memory elements of the system under test by means of FPGAs. This approach takes benefit of the FPGA architecture to minimise the reconfiguration time for SEU injection, obtaining an speed-up of near two orders of magnitude.

A lab course of computer organization

Lecture topics in Computer Organization courses offered by different Universities around the world do not differ significantly. This is because, in general, lecturers use the same textbooks and are inspired by common curriculum sources. However, lab courses and project assignments require more and more expensive resources (computers, assemblers or assembler simulators, logic circuit simulators, ...) This fact, together with the rapid advance of these tools, causes lab courses to widely differ among universities. This paper summarizes the lab course on Computer Organization offered this year at the Technical University of Valencia, Spain. The course is composed by several experiences and jobs, each one aimed at working on one specific topic. Our goal is not only to introduce the tackled topics, but also to discuss some characteristics of the tools. All the tools used are freely available, which is a must for the students to be more motivated and to be able to extend their work using their own computers at home.

Design of a Middleware and Optimization Algorithms for Light Comfort in an Intelligent Environment

The evolution of technology allows to people with special capabilities of mobility to perform the activities faster and easier. The intelligent environments combined with optimization algorithms and middleware agents could help to this aim. This paper presents the design and the implementation of an architecture of a middleware agent that allows us to make the communication between heterogeneous devices (sensors and actuators of different communication protocols from WiFi to ZigBee). On the other hand, we present a comparison study between micro-algorithms used to get lighting comfort in order to perform an activity in a confined space; this is affect by the light from the outside, which can be blocked by shutters and doors, and lighting of lamps obtained within this space. The micro-algorithm evaluated were: Genetic Algorithm (GA), Artificial Immune System (AIS), Estimation Distribution Algorithm (EDA), Particle Swarm Optimization (PSO), Bee Algorithm (BA) and Bee Swarm Optimization (BSO).