Compiler-Injected SIHFT for Embedded Operating Systems

Random hardware faults are a major concern for critical systems, especially when they are employed in high-radiation environments such as aerospace applications. While specialised hardware already exists for implementing fault tolerance, software solutions, named Software-Implemented Hardware Fault Tolerance (SIHFT), offer higher flexibility at a lower cost. This work describes a compiler-based approach for inserting instruction-level fault detection mechanisms in both the application code and the operating system. An experimental evaluation on a STM32 board running FreeRTOS shows the effectiveness of the proposed approach in detecting faults

A Hardware Time Manager Implementation for the Xenomai Real-Time Kernel of Embedded Linux

Nowadays, the use of embedded operating systems in different embedded projects is subject to a tremendous growth. Embedded Linux is becoming one of those most popular EOSs due to its modularity, efficiency, reliability, and cost. One way to make it hard real-time is to include a real-time kernel like Xenomai. One of the key characteristics of a Real-Time Operating System (RTOS) is its ability to meet execution time deadlines deterministically. So, the more precise and flexible the time management can be, the better it can handle efficiently the determinism for different embedded applications. RTOS time precision is characterized by a specific periodic interrupt service controlled by a software time manager. The smaller the period of the interrupt, the better the precision of the RTOS, the more it overloads the CPU, and though reduces the overall efficiency of the RTOS. In this paper, we propose to drastically reduce these overheads by migrating the time management service of Xenomai into a configurable hardware component to relieve the CPU. The hardware component is implemented in a Field Programmable Gate Array coupled to the CPU. This work was achieved in a Master degree project where students could apprehend many fields of embedded systems: RTOS programming, hardware design, performance evaluation, etc.Comment: Embed With Linux (EWiLi) workshop, Lorient : France (2012

An Experimental Nexos Laboratory Using Virtual Xinu

The Nexos Project is a joint effort between Marquette University, the University of Buffalo, and the University of Mississippi to build curriculum materials and a supporting experimental laboratory for hands-on projects in computer systems courses. The approach focuses on inexpensive, flexible, commodity embedded hardware, freely available development and debugging tools, and a fresh implementation of a classic operating system, Embedded Xinu, that is ideal for student exploration. This paper describes an extension to the Nexos laboratory that includes a new target platform composed of Qemu virtual machines. Virtual Xinu addresses two challenges that limit the effectiveness of Nexos. First, potential faculty adopters have clearly indicated that even with the current minimal monetary cost of installation, the hardware modifications, and time investment remain troublesome factors that scare off interested educators. Second, overcoming the inherent complications that arise due to the shared subnet that result in students\u27 projects interfering with each other in ways that are difficult to recreate, debug, and understand. Specifically, this paper discusses porting the Xinu operating systems to Qemu virtual hardware, developing the virtual networking platform, and results showing success using Virtual Xinu in the classroom during one semester of Operating Systems at the University of Mississippi

XinuPi3: Teaching Multicore Concepts Using Embedded Xinu

As computer platforms become more advanced, the need to teach advanced computing concepts grows accordingly. This paper addresses one such need by presenting XinuPi3, a port of the lightweight instructional operating system Embedded Xinu to the Raspberry Pi 3. The Raspberry Pi 3 improves upon previous generations of inexpensive, credit card-sized computers by including a quad-core, ARM-based processor, opening the door for educators to demonstrate essential aspects of modern computing like inter-core communication and genuine concurrency. Embedded Xinu has proven to be an effective teaching tool for demonstrating low-level concepts on single-core platforms, and it is currently used to teach a range of systems courses at multiple universities. As of this writing, no other bare metal educational operating system supports multicore computing. XinuPi3 provides a suitable learning environment for beginners on genuinely concurrent hardware. This paper provides an overview of the key features of the XinuPi3 system, as well as the novel embedded system education experiences it makes possible

Real-Time Operating Systems and Programming Languages for Embedded Systems

In this chapter, we present the different alternatives that are available today for the development of real-time embedded systems. In particular, we will focus on the programming languages use like C++, Java and Ada and the operating systems like Linux-RT, FreeRTOS, TinyOS, etc. In particular we will analyze the actual state of the art for developing embedded systems under the WORA paradigm with standard Java [1], its Real-Time Specification and with the use of Real-Time Core Extensions and pico Java based CPUs [5]. We expect the reader to have a clear view of the opportunities present at the moment of starting a design with its pros and cons so it can choose the best one to fit its case.Fil: Orozco, Javier Dario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; Argentina. Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Laboratorio de Sistemas Digitales; ArgentinaFil: Santos, Rodrigo Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; Argentina. Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Laboratorio de Sistemas Digitales; Argentin

Restart-Based Fault-Tolerance: System Design and Schedulability Analysis

Embedded systems in safety-critical environments are continuously required to deliver more performance and functionality, while expected to provide verified safety guarantees. Nonetheless, platform-wide software verification (required for safety) is often expensive. Therefore, design methods that enable utilization of components such as real-time operating systems (RTOS), without requiring their correctness to guarantee safety, is necessary. In this paper, we propose a design approach to deploy safe-by-design embedded systems. To attain this goal, we rely on a small core of verified software to handle faults in applications and RTOS and recover from them while ensuring that timing constraints of safety-critical tasks are always satisfied. Faults are detected by monitoring the application timing and fault-recovery is achieved via full platform restart and software reload, enabled by the short restart time of embedded systems. Schedulability analysis is used to ensure that the timing constraints of critical plant control tasks are always satisfied in spite of faults and consequent restarts. We derive schedulability results for four restart-tolerant task models. We use a simulator to evaluate and compare the performance of the considered scheduling models

Linux kernel compaction through cold code swapping

There is a growing trend to use general-purpose operating systems like Linux in embedded systems. Previous research focused on using compaction and specialization techniques to adapt a general-purpose OS to the memory-constrained environment, presented by most, embedded systems. However, there is still room for improvement: it has been shown that even after application of the aforementioned techniques more than 50% of the kernel code remains unexecuted under normal system operation. We introduce a new technique that reduces the Linux kernel code memory footprint, through on-demand code loading of infrequently executed code, for systems that support virtual memory. In this paper, we describe our general approach, and we study code placement algorithms to minimize the performance impact of the code loading. A code, size reduction of 68% is achieved, with a 2.2% execution speedup of the system-mode execution time, for a case study based on the MediaBench II benchmark suite

Hardware Monitors for Secure Processing in Embedded Operating Systems

Embedded processors are being increasingly used in our daily life and have become an important part of many types of infrastructure in the world. As people start depending more on embedded systems for personal and business processing operations, the attacks on these systems have also been on a rise. Existing defense mechanisms targeted for desktop and server processors cannot be used to defend embedded systems as these system exhibit constraints on processing performance and processing power and energy. Thus, embedded systems require low overhead security approaches to ensure that they are protected from attacks. This thesis describes a hardware based approach to monitor the operation of an embedded processor instruction-by-instruction, where deviations from expected program behavior are detected within the time associated with the execution of an instruction. Previous work in this area has focused on monitoring a single task on a CPU while here a novel hardware monitoring system that can monitor multiple active tasks in an operating-system-based platform is presented. This approach doesn’t need any change in application binary code. The hardware monitor is able to track context switches that occur in the operating system and ensure that monitoring is performed continuously, thus ensuring system security. This thesis describes the design of the system as well as results obtained from a prototype implementation of the system on an Altera DE4 FPGA board. It is demonstrated in hardware that applications can be monitored at instruction level without execution slow-down and buffer overflow attacks can be defeated using this system. When an attack occurs, it is detected within a cycle and the attack task is killed before it can harm the system. The system uses an off-chip DRAM for storing the application binary and the operating system kernel. A centralized graph memory is implemented on-chip to support the storage of all monitoring graphs associated with the system. MiBench benchmarks such as qsort, bitcount, stringmatch, basicmath and dijkstra are used to evaluate the system

User-Behavior-Guided Dynamic Loaders in Embedded Operating Systems

This publication describes a new user-behavior-guided dynamic loader in embedded operating systems (OS). It is well-understood that embedded devices, such as smartphones, are constrained in their random-access memory (RAM) resource. To better utilize the RAM resource, developers use shared libraries when building their application software (often referred to as apps or applications). Shared libraries reduce the memory footprint of individual application software. However, the utilization of shared libraries, even though beneficial in minimizing the volatile memory footprint, comes at a performance cost. The performance is improved, however, when shared libraries are pre-loaded before the application software is accessed by the end user. Current OS platforms lack the heuristic guided approach to predict which shared libraries are going to be needed at the time the end user accesses the application software. To this end, a new dynamic loader is developed to help predict the pre-loading of the needed shared libraries. To enable the OS to predict and pre-load shared libraries tailored to the end user, the new user-behavior-guided dynamic loader employs three components: user embedding, current time, and current location. To improve the performance of the dynamic loader, federated learning is utilized to democratize the computational power needed and benefit from each end user’s input data. By so doing, the described techniques optimize the prediction of the relevant shared libraries to be pre-loaded, while protecting the end user’s privacy. Consequently, user-behavior-guided dynamic loaders reduce the memory pressure of the embedded devices, while optimizing the performance of these devices