[jdblair]

You could make a multi-tasking os with no memory protection (kind of like AmigaOS), and with a partially posix api. Is that still Linux?

[AlotOfReading]

That's basically just NuttX. Along similar lines is Zephyr, which is actually managed by the Linux foundation and broadly follows kernel conventions where reasonable.

[bestouff]

Yes, that's called uCLinux - linux without an MMU.

[swagempire]

Wait, isn't this Fuzix?

https://hackaday.com/2017/04/16/z80-fuzix-is-like-old-fashio...

[ladyanita22]

Yes, such a thing exists and its a build flag in the Linux kernel.