cross-port from: https://programming.dev/post/5377847

Ironclad is a formally verified, hard real-time capable kernel for general-purpose and embedded uses, written in SPARK and Ada. It is comprised of 100% free software, free in the sense that it respects the user’s freedom.

Some of the supported features are:

• A familiar POSIX-compatible interface.
• True simultaneous preemptive multitasking.
• Advanced cryptography and a security-centered architecture.
• Mandatory Access Control (MAC).
• Highly configurable, hard real-time scheduling.
• Support for several architectures and boards.

Today (4 Nov 2023) at 14:00 UTC the author will preset it on Ada Monthly Meetup!