Safety-related systems, such as those in automotive, avionics and space, impose the existence of appropriate safety measures to meet the safety requirements of the system. In the case of the highest integrity level functionalities (e.g. ASIL-D in automotive), diverse redundancy must be deployed to avoid unreasonable risk of a single fault leading the system to a failure (e.g. using lockstepped cores). However, existing lockstep solutions are either (1) highly intrusive and inflexible coupling two cores with hardware means, or (2) costly in terms of execution time and monitoring if a software monitor thread checks that cores running redundantly preserve sufficient staggering. This paper presents SafeDE, a Diversity Enforcement hardware module providing light-lockstep support by means of a non-intrusive and flexible hardware module that preserves staggering across cores running redundant threads, thus bringing time diversity. SafeDE reconciles the lightness and flexibility of software-only solutions, even allowing using the cores without any lockstepping, as well as the tighter staggering of hardware-only solutions that allow using staggering values of few cycles, instead of hundreds of microseconds, as for software-only solutions. Our integration of SafeDE in a RISC-V FPGA-based space multicore from Cobham Gaisler shows that staggering is effectively preserved, and SafeDE overheads are negligible in terms of area and performance due to staggering.

Functional and timing validation of safety-related MPSoCs requires testing specific traffic patterns in the on-chip interconnects. Generally, testing needs to be performed by using software tests whose degree of control on the traffic generated is indirect, and limited to behavior that can be triggered by software, thus often unable to produce traffic generated by peripherals. Therefore, untested traffic scenarios can be abundant and, to a large extent, it is hard to know what traffic scenarios have been effectively tested. This paper presents the safe traffic injector, SafeTI, which allows injecting programmable traffic in AMBA AHB interconnects with high flexibility and degree of control, thus easing achieving high coverage in terms of traffic scenarios tested, and mitigating the uncertainty due to the difficulties to relate software tests with actual traffic scenarios tested. We also integrate successfully the SafeTI in an industrial MPSoC for the space domain proving the effectiveness of the proposed traffic injector.