Michael Hohmuth

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First-generation μ-kernels have a reputation for being too slow and lacking sufficient flexibility. To determine whether L4, a lean second-generation μ-kernel, has overcome these limitations, we have repeated several earlier experiments and conducted some novel ones. Moreover, we ported the Linux operating system to run on top of the L4 μ-kernel and(More)
3rd IEEE Real-time Technology and Applications Symposium (RTAS), June 1997 in Montreal, Canada Cache-partitioning techniques have been invented to make modern processors with an extensive cache structure useful in real-time systems where task switches disrupt cache working sets and hence make execution times unpredictable. This paper describes an(More)
The characterising new requirement for distributed multimedia applications is the coexistence of dynamic real-time and non-real-time applications on hosts and networks. While some networks (e.g., ATM) in principle have the capability to reserve bandwidth on shared links, host systems usually do not. DROPS (Dresden Real-time OPerating System) is being built(More)
AMD's Advanced Synchronization Facility (ASF) is an x86 instruction set extension proposal intended to simplify and speed up the synchronization of concurrent programs. In this paper, we report our experiences using ASF for implementing transactional memory. We have extended a C/C++ compiler to support language-level transactions and generate code that(More)
Advanced Synchronization Facility (ASF) is an AMD64 hardware extension for lock-free data structures and transactional memory. It provides a speculative region that atomically executes speculative accesses in the region. Five new instructions are added to demarcate the region, use speculative accesses selectively, and control the speculative hardware(More)
We present the VFiasco project, in which we apply source-code verification to a complete operating-system kernel written in C++. The aim of the VFiasco project is to establish security-relevant properties of the Fiasco microkernel.Source-code verification works by reasoning about the semantics of the full source code of a program. Traditionally it is(More)
We present a pragmatic methodology for designing nonblocking real-time systems. Our methodology uses a combination of lock-free and wait-free synchronization techniques and clearly states which technique should be applied in which situation. This paper reports novel results in various respects: We restrict the usage of lock-free mechanisms to cases where(More)
This paper describes the overall design, partial implementation and brief performance evaluation of a system in which Linux and its applications run besides real-time applications. The separation of the real-time and time-sharing subsystems is not restricted to the use of the CPU but enforced as well for other resources, namely main memory and caches. This(More)
Secure systems are best built on top of a small trusted operating system: The smaller the operating system, the easier it can be assured or verified for correctness.In this paper, we oppose the view that virtual-machine monitors (VMMs) are the smallest systems that provide secure isolation because they have been specifically designed to provide little more(More)
The trusted computing bases (TCBs) of applications running on today's commodity operating systems have become extremely large. This paper presents an architecture that allows to build applications with a much smaller TCB. It is based on a kernelized architecture and on the reuse of legacy software using trusted wrappers. We discuss the design principles,(More)