Critical embedded systems deserve the highest level of assurance to guarantee that their implementation satisfies their specification. Verification techniques such as proof by deduction operate at source level but the verification effort often requires to design higher-level abstractions that facilitate the reasoning. However, this approach comes at the cost of assuming the correctness of the abstraction with respect to the source code.

Partitioning kernels often face challenges such as static resource allocation and insufficient temporal protection, limiting their applicability in dynamic and mixed-criticality systems where resource needs and security boundaries evolve over time. To address these limitations, we present S3K, a capability-based multicore partitioning kernel for embedded RISC-V systems. S3K provides robust spatial and temporal isolation, time protection, and dynamic resource reconfiguration, enabling flexible adaptation to changing operational requirements while maintaining strong safety and security guarantees. Its capability-based model ensures secure and efficient resource management, while in-kernel data partitioning prevents information leakage and mitigates side-channel attacks. Additionally, S3K's scheduler guarantees deterministic process dispatch, free from microarchitectural interference. Evaluation results demonstrate S3K's effectiveness, showing the absence of scheduling jitter, resistance to intra-core side-channels, and efficient interprocess communication. These results highlight S3K's suitability for safety-critical and security-critical applications in dynamic, resource-constrained environments.