> 2. POSIX compatibility layer. Even embedded OSes without the concept of threads or processes can implement POSIX. Do you have resources about this? I can't q

> 2. POSIX compatibility layer. Even embedded OSes without the concept of threads or processes can implement POSIX. Do you have resources about this? I can't quite fathom how it would work, but then again I have no expertise. > 3. Hypervisor. They're much easier to add with intel's VT-[xd]. Failing that, fall back to emulation. Translational emulation is very performant. Speaking of which, QubesOS was on HN recently. The essence is having many VMs to minimize cross-app attack surface and privilege escalation. > 6. The failure of pure microkernel was the added complexity and management of sequencing multiple resources in a transactional manner. There are great theoretical security and operational advantages in microkernel architectures but they never caught on widely in a pure form. I recently saw an interesting brief article[0] about how memory-safe languages can supercede the compartmentalization that microkernels provide. I'm reminded of Theseus[1], written in rUsT, which happens to reflect the sentiment. I've actually been putting off rereading the Theseus USENIX paper. Again, I'm not nearly qualified to answer whether the security of this is comparable to the best of that of microkernels, barring formal verification. Still, I think it should be explored more. [0] https://catern.com/microkernels.html (Write modules, not microkernels) [1] https://www.usenix.org/conference/osdi20/presentation/boos