Despite growing efforts and encouraging successes in recent decades, fully formally verified projects are still rare in the industrial landscape. The industry often lacks the tools and methodologies to efficiently scale the proof development process. In this work, we give a comprehensible overview of the proof development process for proof developers and project managers. The goal is to support proof developers by rationalizing the proof development process, which currently relies heavily on their intuition and expertise, and by facilitating communication with the management line. To this end, we concentrate on the aspect of proof manufacturing and highlight the most significant sources of proof effort. We propose means to mitigate the latter through proof practices (proof structuring, proof strategies, and proof planning), proof metrics, and tools. Our approach is project-agnostic, independent of specific proof expertise, and computed estimations do not assume prior similar developments. We evaluate our guidelines using a separation kernel undergoing formal verification, driving the proof process in an optimised way. Feedback from a project manager unfamiliar with proof development confirms the benefits of detailed planning of the proof development steps, clear progress communication to the hierarchy line, and alignment with established practices in the software industry.

For security and safety reasons, it is essential to ensure memory isolation between processes. The memory manager is thus a critical part of the kernel of an operating system. It is common for kernels to ensure memory isolation through a piece of hardware called memory management unit (MMU). However an MMU by itself does not provide memory isolation. It is only a tool the kernel can use to ensure this property. In this paper we show how a proof assistant such as Coq can be used to model a hardware architecture with an MMU, and an abstract model of microkernel supporting preemptive scheduling and memory manager. We proceed by making formally explicit the consistency properties that must be preserved in order for memory isolation to be preserved.