Automatic Generation of Schedulings for Improving the Test Coverage of Systems-on-a-Chip

International audienceSystemC is becoming a de-facto standard for the early simulation of Systems-on-a-chip (SoCs). It is a parallel language with a scheduler. Testing a SoC written in SystemC implies that we execute it, for some well chosen data. We are bound to use a particular deterministic implementation of the scheduler, whose specification is non-deterministic. Consequently, we may fail to discover bugs that would have appeared using another valid implementation of the scheduler. Current methods for testings SoCs concentrate on the generation of the inputs, and do not address this problem at all. We assume that the selection of relevant data is already done, and we generate several schedulings allowed by the scheduler specification. We use dynamic partial-order reduction techniques to avoid the generation of two schedulings that have the same effect on the system's behavior. Exploring alternative schedulings during testing is a way of guaranteeing that the SoC description, and in particular the embedded software, is scheduler-independent, hence more robust. The technique extends to the exploration of other non-fully specified aspects of SoC descriptions, like timing

Testbench qualification of SystemC TLM protocols through Mutation Analysis

Transaction-level modeling (TLM) has become the de-facto reference modeling style for system-level design and verification of embedded systems. It allows designers to implement high-level communication protocols for simulations up to 1000x faster than at register-transfer level (RTL). To guarantee interoperability between TLM IP suppliers and users, designers implement the TLM communication protocols by relying on a reference standard, such as the standard OSCI for SystemC TLM. Functional correctness of such protocols as well as their compliance to the reference TLM standard are usually verified through user-defined testbenches, which high-quality and completeness play a key role for an efficient TLM design and verification flow. This article presents a methodology to apply mutation analysis, a technique applied in literature for SW testing, for measuring the testbench quality in verifying TLM protocols. In particular, the methodology aims at (i) qualifying the testbenches by considering both the TLM protocol correctness and their compliance to a defined standard (i.e., OSCI TLM), (ii) optimizing the simulation time during mutation analysis by avoiding mutation redundancies, and (iii) driving the designers in the testbench improvement. Experimental results on benchmarks of different complexity and architectural characteristics are reported to analyze the methodology applicability

TLM.open: a SystemC/TLM Front-end for the CADP Verification Toolbox

Extended abstract for SBDCES workshop (http://unit.aist.go.jp/cvs/workshop/SBDCES.html)SystemC/TLM models allow the simulation of the embedded software before the hardware RTL descriptions are available, and are used as golden models for hardware verification. The verifi- cation of the SystemC/TLM models is an important issue, since a error in the model can mislead the system designers, or reveal an error in the specification. The OSCI provides an open-source simulator for SystemC/TLM but no tools for formal verification. In order to apply model checking to a SystemC/TLM program, the usual approach relies on the translation of the SystemC/TLM code to a formal language for which a model checker is available. We propose another approach that suppress the error-prone translation effort. Given a SystemC/TLM program, we execute the transitions using g++ and the OSCI library, and we ask the user to provide additional functions to store the current program state. These additional functions represent generally less than 20% of the size of the origianl model, and allows to apply all CADP tools to the SystemC/TLM program itself

The COMPLEX reference framework for HW/SW co-design and power management supporting platform-based design-space exploration

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Modélisation à haut niveau d'abstraction pour les systèmes embarqués

Modern embedded systems have reached a level of complexity such that it is no longer possible to wait for the first physical prototypes to validate choices on the integration of hardware and software components. It is necessary to use models, early in the design flow. The work presented in this document contribute to the state of the art in several domains. First, we present some verification techniques based on abstract interpretation and SMT-solving for programs written in general-purpose languages like C, C++ or Java. Then, we use verification tools on models written in SystemC at the transaction level (TLM). Several approaches are presented, most of them using compilation techniques specific to SystemC to turn the models into a format usable by existing tools. The second part of the document deal with non-functional properties of models: timing performances, power consumption and temperature. In the context of TLM, we show how functional models can be enriched with non-functional information. Finally, we present contributions to the modular performance analysis (MPA) with real-time calculus (RTC) framework. We describe several ways to connect RTC to more expressive formalisms like timed automata and the synchronous language Lustre. These connections raise the problem of causality, which is defined formally and solved with the new causality closure algorithm.Les systèmes embarqués modernes ont atteint un niveau de complexité qui fait qu'il n'est plus possible d'attendre les premiers prototypes physiques pour valider les décisions sur l'intégration des composants matériels et logiciels. Il est donc nécessaire d'utiliser des modèles, tôt dans le flot de conception. Les travaux présentés dans ce document contribuent à l'état de l'art dans plusieurs domaines. Nous présentons dans un premier temps de nouvelles techniques de vérification de programmes écrits dans des langages généralistes comme C, C++ ou Java. Dans un second temps, nous utilisons des outils de vérification formelle sur des modèles écrits en SystemC au niveau transaction (TLM). Plusieurs approches sont présentées, la plupart d'entre elles utilisent des techniques de compilations spécifiques à SystemC pour transformer le programme SystemC en un format utilisable par les outils. La seconde partie du document s'intéresse aux propriétés non-fonctionnelles des modèles~: performances temporelles, consommation électrique et température. Dans le contexte de la modélisation TLM, nous proposons plusieurs techniques pour enrichir des modèles fonctionnels avec des informations non-fonctionnelles. Enfin, nous présentons les contributions faites à l'analyse de performance modulaire (MPA) avec le calcul temps-réel (RTC). Nous proposons plusieurs connections entre ces modèles analytiques et des formalismes plus expressifs comme les automates temporisés et le langage de programmation Lustre. Ces connexion posent le problème théorique de la causalité, qui est formellement défini et résolu avec un algorithme nouveau dit de " fermeture causale "