Dependability Threats

Abstract

The increasing diversity, density, and complexity of electronic devices is enabling the so-called digital revolution with the evident pervasive presence of electronics in everybody's lives. The benefits of this ubiquitous presence are impressive and widespread: from the constant improvement of productivity in the workplace to the societal impact of a constantly connected and sharing community.Whatever is the considered scenario, all this incredible progress has been relying on the assumption that the devices can be depended on in their application and for their purposes. The foundations for this assumption are based on a constant work behind the scenes of the technical and scientific community aimed at enhancing the dependability of the devices.Dependability is a broad term that summarizes several aspects of a system, which typically include availability, reliability, maintainability, safety, and security. All these aspects define whether and how the system will behave according to several requirements which can have different levels of priority based on the specific application. In particular, availability measures the amount of time a system is readily operating, reliability measures the continuity of the correct service, maintainability shows the ability of the system of being repaired and/or modified, safety targets the avoidance of catastrophic consequences in the case of lack of service, and finally security targets the resilience of a systems to threats caused by malicious third parties.There is an impressive amount of examples from technical literature and from the news about the dreadful consequences of the lack of dependability of an electronic system. Lack of dependability may have several negative consequences spreading from the loss of reputation of a manufacturer to the catastrophic loss of lives. Consider for example the automotive scenario, several cases of massive recalls were caused by issues in the electronic system: famously in one of such cases it was speculated that unintended acceleration causing loss of lives was to be ascribed to faults occurring in the drive-by-wire control modules.Apart from the loss of lives, the economic impact of unreliable hardware must also be taken into account. Depending on the particular product and application domain, the costs associated to lack of dependability can be extremely high:xiii

Multi-core Devices for Safety-critical Systems

“…The latest manufacturing processes are already producing 7 nm devices thanks to the advances in CMOS downscaling technology, manufacturing processes and electronic design automation tools [5,18]. Nevertheless, this CMOS technology downscaling leads to several threats that contribute to reliability degradation such as [32,33,34,5,35,36]:…”

“…• Transient faults and soft errors: Soft-errors are caused by environmental conditions (e.g., α-particles, cosmic rays, ionizing radiation, EMI, cross-talk) leading to a transient perturbation that can be manifested as memory bit-flip in memory cells or combinatorial logic result error [32,33,39]. If the perturbation affects a single cell the event is called Single Event Upset (SEU), and if it affects more than one the event is called Multiple Bit Upset (MBU).…”

“…• Permanent faults: Permanent faults are those whose presence is persistent and permanently affect the correct functional behavior of the system [1,33]. As the technology continues to shrink and device complexity continues to increase, the probability of physical defects in the hardware (e.g., short-circuit) during lifetime of a system continues to increase, from rare improbable events to probable events, and therefore error tolerance and diagnosis becomes also important to ensure the reliable and safe operation of the device [33].…”