Depends what you call kernel space For example, nebulet https://github.com/nebulet/nebulet https://github.com/nebulet/nebulet wanted to run everything in ring

Depends what you call kernel space For example, nebulet https://github.com/nebulet/nebulet https://github.com/nebulet/nebulet wanted to run everything in ring 0, but "userspace" was WebAssembly code that had been compiled by "kernelspace" to run sandboxed in ring 0 If a CPU architecture was implemented to only offer ring 0, would a microkernel be impossible? Or would we accept this concept of kernelspace/userspace being implemented in software?