SysWCET: Cross-Kernel Response-Time Analysis for Fixed-Priority Real-Time Systems” Christian Dietrich, Peter Wägemann, Peter Ulbrich, Daniel Lohmann Abstract: The worst-case response time (WCRT) – the time span from release to completion of a real-time task – is a crucial parameter in real-time system design. However, WCRT analysis can be complex in practice, as it depends not only on the realistic examination of worst-case execution times (WCET), but also on system-level overheads, blocking/preemption times, and more. While implicit path enumeration (IPET) has greatly improved automated WCET analysis, the resulting values still need be be aggregated manually with the system-level overheads – an error- prone and tedious process that yields overly pessimistic results. With SysWCET, we provide a constructive approach for the automated WCRT analysis across multiple threads of execution, locks, interrupt service routines, and the real-time operating system (RTOS). Our whole-system approach spans a single IPET over all tasks and the RTOS and exploits RTOS and scheduler semantics to derive cross-kernel flow facts. The WCRT analysis extracts the possible system-wide control flows and integrates them with the kernel code and an environment model for interrupts and significantly reduces pessimism in WCRT analysis. We evaluate our approach with a fully functional implementa- tion of SysWCET for the automotive OSEK-OS standard (ECC1), including threads, alarms, ISRs, events and PCP-based resource management.