On-The-Fly Metadata Stripping For Embedded Java Operating Systems

International audienceConsidering the typical amount of memory available on a smart card, it is essential to minimize the size of the runtime environment to leave as much memory as possible to applications. This paper shows that on-the-fly constant pool packing can result in a significant reduction of the memory footprint of an embedded Java runtime environment. We first present Jits, an architecture dedicated to building fully-customized Java runtime environments for smart cards. We then detail the op- timizations we have implemented in the class loading mechanism of Jits to reduce the size of the loaded class constant pool. By suppress- ing constant pool entries as they become unnecessary during the class loading process, we manage to compact constant pools of loaded classes to less than 8% of their initial size. We then present the results of our mechanism in term of constant pool and class size reductions, and conclude by suggesting some more aggressive optimizations

Trusted Collaborative Real Time Scheduling in a Smart Card Exokernel

This paper presents the work we have conducted concerning real time scheduling in Camille, an exokernel dedicated to smart cards. We show that it is possible to embedded a flexible real-time operating system despite the important hardware limitations of the smart card platform. We present the major difficulties one has to face when integrating real time support in an exokernel embedded on a very resource-limited platform. We first present a naive solution consisting in allocating an equal time slice to every system extensions and letting each one share it as needed amongst its tasks. We show that this solution does not account for loading of new extensions in the system, and that it can fail if some extensions have much more work to carry out than the others. We then present a more complex solution based upon collaborative schedulers grouped as virtual extensions. We show that this solution supports dynamic loading of new extensions and works even for very unbalanced task repartitions. We finally address the issue of trust between the collaborating extensions and we propose a solution based on exhaustive testing and formal proving of the plan functions

A Distributed WCET Computation Scheme for Smart Card Operating Systems

Computing WCET in a resource-constrained device such as a smart card in a safe manner raises some difficulties. In- deed, most of the classical algorithms for computing WCET do not address resource-limitation or security issues. In this article, we propose to distribute the computation process between the off-card part running on a powerful workstation and the on-card part specific to the hardware included in the smart card. We also guarantee the safety of our com- putation process by inserting assertions in the generated code and preventing information leaks from the card to the outside

Alternative schemes for low-footprint operating systems building

This paper presents two ways of building dedicated embedded operating systems. The constructive approach consists in starting from a minimal kernel and adding abstractions as they are needed, whereas the destructive approach promotes the idea of customizing an existing operating system by removing unnecessary abstractions. We compare these two approaches on the example of building an embedded Java operating system and discuss the pros and cons of each method. We conclude by exhibiting the weakness of each approaches concerning dynamic adaptation of the system

Flexible Bindings for Type-Safe Embedded Operating Systems.

This paper presents the binding model implemented in Camille, an extensible operating system for resource-limited devices. Modern embedded systems need on the first hand to fully exploit the limited hardware on which they run and on the other hand to dynamically adapt themselves to changes in their runtime environment. Camille is an exokernel which support static customization of components and dynamic loading of system extensions. Dynamic kernel and application adaptation is implemented by an inter-component communication model. This model is based on flexible bindings which permit to fully customize the way components interact with each others. Bindings can be static, virtual or compiled to guarantee performances of inter-component communications. This paper shows that it is possible to build a flexible operating system without sacrificing runtime performances, even for devices as constrained as smart cards. We first present the architecture of the Camille exokernel and the intermediate language Facade into which applications and system components are translated to ease type verification. We then describe the component model implemented in Camille and the inter-component communication scheme based on embedded binding factories. We then details the binding generation process and the various verifications which can be enforced when implementing bindings. We present some experimental results we have obtained when monitoring the performances of our native code generator. Finally, we conclude and discuss the future work we plan to conduct concerning extraction of selected properties from generated code

Extensions Temps-Réel pour Exo-Noyau Embarqué

Les cartes à puces sont des petits objets portables axés principalement sur la sécurité ($10^9$ unités vendues principalement en Asie et en Europe). Afin de permettre aux logiciels encartés de supporter plus de services, les systèmes d'exploitation pour cartes ont évolué d'une plateforme d'exécution monolithique dédiée vers des architectures systèmes plus ouvertes qui supportent le chargement dynamique de code. Cet article présente les problèmes temps-réel du système d'exploitation pour carte Camille, qui présente les caractéristiques suivantes : chargement dynamique de code, vérification de type embarquée, compilation à la volée, et chargement dynamique de composants systèmes. D'une manière plus générale, il traite des difficultés à accorder les extensions temps-réel avec les principes des exo-noyaux

Réalisation d’un Contrat d’Etudes Prospectives des secteurs du transport: Rapport final

Le CEP a pour objectif de réaliser un état des lieux du secteur, de conduire une analyse prospective qualitative et quantitative de l’évolution des métiers et des besoins de compétences du transport et de préconiser un plan d’actions pour les transports routiers, maritimes et fluviaux. A l’issue des travaux d’étude, le rapport final a été remis aux membres du Comité de pilotage (Ministère de l’emploi - DGEFP, Représentants des branches des transports, l’OPCA Transports et Services, Pôle Emploi, Ministère de l’écologie et du développement durable, des transport et du logement)

L'Hydroptère: A story of a dream

In 2009, l’Hydroptère broke the symbolic barrier of 50 knots and became the world fastest sailing boat over both 500 meters and 1 nautical mile. This major achievement relied on the high skills of the sailing team but also on technical advances of the boat, resulting from long years of studies and development. This achievement is also an open window to a new goal: flying around the world. In the present article, we present this long and incredible story, highlighting the different steps, the technology involved, and the background of that project.

Lecture paysagère de la précarité à Alès : de la crise urbaine à la pratique agricole

Cette communication traite de la pratique agricole comme outil d'égalité sociale dans les villes en crises. Elle présente une analyse des processus de précarité présents dans la ville d'Alès, pour comprendre en quoi la pratique agricole constitue une stratégie d'adaptation des populations pauvres à la crise. Elle s'appuie sur l'hypothèse que le retour à la terre répond d'abord à des motivations économiques mais que ces dernières sont indissociables de toute une série de motivations qui questionnent la citoyenneté en ville