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We propose a method to reuse unmodified device drivers and to improve system dependability using virtual machines. We run the unmodified device driver, with its original operating system, in a virtual machine. This approach enables extensive reuse of existing and unmodified drivers, independent of the OS or device vendor, significantly reducing the barrier to building new OS endeavors. By allowing distinct device drivers to reside in separate virtual machines, this technique isolates faults caused by defective or malicious drivers, thus improving a system’s dependability. We show that our technique requires minimal support infrastructure and provides strong fault isolation. Our prototype’s network performance is within 3–8 % of a native Linux system. Each additional virtual machine increases the CPU utilization by about 0.12%. We have successfully reused a wide variety of unmodified Linux network, disk, and PCI device drivers. 1

The goal of Denali is to safely execute many independent, untrusted server applications on a single physical machine. This would enable any developer to inject a new service into third-party Internet infrastructure; for example, dynamic content generation code could be introduced into content-delivery networks or caching systems. We believe that virtual machine monitors (VMMs) are ideally suited to this application domain. A VMM provides strong isolation by default, since one virtual machine cannot directly name a resource in another. In addition, VMMs defer the implementation of high-level abstractions to guest OSs, which greatly simplifies the kernel and avoids "layer-below" attacks. The main challenge in using a VMM for this application domain is in scaling the number of concurrent virtual machines that can simultaneously execute on it.

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The first decades of the new millennium will witness an explosive growth in the number and diversity of networked devices. We foresee high degrees of mobility, heterogeneity, and interactions among computing devices connected to global networks. Conventional operating system architectures are inadequate for the wide-area, heterogeneous computing environments of the new millennium. While previous research in distributed operating systems solved many problems related to resource management, they seldom addressed the problems of heterogeneity and dynamic adaptability. On the other hand, middleware solutions, like CORBA and JINI, solve part of the heterogeneity problem by permitting seamless communication among different platforms. But, still, they do not address dynamic, distributed resource management and adaptability. This paper presents 2K, an integrated operating system architecture that addresses the problems of resource management in heterogeneous networks, dynamic adaptability, and configuration of component-based distributed applications. We discuss our rationale, describe our prototype implementation, and point to future directions.

Abstract. We present TinyOS, a flexible, application-specific operating system for sensor networks, which form a core component of ambient intelligence systems. Sensor networks consist of (potentially) thousands of tiny, low-power nodes, each of which execute concurrent, reactive programs that must operate with severe memory and power constraints. The sensor network challenges of limited resources, event-centric concurrent applications, and low-power operation drive the design of TinyOS. Our solution combines flexible, fine-grain components with an execution model that supports complex yet safe concurrent operations. TinyOS meets these challenges well and has become the platform of choice for sensor network research; it is in use by over a hundred groups worldwide, and supports a broad range of applications and research topics. We provide a qualitative and quantitative evaluation of the system, showing that it supports complex, concurrent programs with very low memory requirements (many applications fit within 16KB of memory, and the core OS is 400 bytes) and efficient, low-power operation. We present our experiences with TinyOS as a platform for sensor network innovation and applications. 1

MMLite is a modular system architecture that is suitable for a wide variety of hardware and applications. The system provides a selection of object-based components that are dynamically assembled into a full application system. Amongst these components is a namespace, which supports a new programming model, where components are automatically loaded on demand. The virtual memory manager is optional and is loaded on demand. Components can be easily replaced and reimplemented. A third party independently replaced the real-time scheduler with a different implementation. Componentization reduced the development time and led to a flexible and understandable system. MMLite is efficient, portable, and has a very small memory footprint. It runs on several microprocessors, including two VLIW processors. It is being used on processors that are embedded in a number of multimedia DirectX accelerator boards. 1 Introduction The progressive computerization of our society involves a number of divers...

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We present T2, a second generation sensor network operating system written in the nesC language. We describe why the limitations and problems of current OSes necessitate a new design. T2 improves on current systems in three areas: platform support, application construction, and reliability. We argue that existing systems neglected these properties in order to maximize flexibility. In contrast, T2 limits flexibility to that which applications need, and leverages these constraints to improve the rest of the system. We evaluate T2 in comparison to TinyOS, and show how its structure simplifies applications, makes porting to a new platform much easier, and improves system reliability. From these results, we discuss the frictions present in component-based OSes and how T2’s design and structure makes dealing with them more tractable. 1

Deeply embedded systems are forced to operate under extreme resource constraints in terms of memory, CPU, time, and power consumption. Typical examples are automotive systems. Today's limousines can be considered (large scale) distributed systems on wheels. There are cars in daily operation consisting of over 60 networked processors (i. e. µ-controllers). Reserved estimations say that in the near future every car will be equipped with about 20 networked µ-controllers, on average. The complexity of these "decentralized computer architectures" can be managed no longer by the application alone. Dedicated embedded operating systems are required to ensure manageability, adaptability, portability, and yet efficiency of the software. Resource sparing operation under (hard) real-time constraints must be the maxim. This paper discusses the design and implementation of a portable, universal runtime executive, PURE, for these classes of deeply embedded systems.