It’s a little different scenario: You don’t need to have a 486 to compile the Linux kernel for a 486. It’s not even cross compilation, it’s just setting particular flags and how to do the compile and what processor features to enable or not. It’s probably useful to test it periodically on the actual processor but in a strict sense it’s not needed.
You do, in general, need to be running on a 68000 to compile parts of the actual whole OS for 68000, since so much stuff is different or custom for each architecture and there is plenty of work involved without trying to introduce emulation or cross-compilation into the mix in any way.
remotelove@lemmy.ca 3 days ago
You can generally cross compile across architectures, but there can be instruction or build nuances that can cause hiccups. Also, you need to build everything against the target architecture as well, not just the kernel.