We've seen CPU-capability differences by accident a few times, and it's always a chaotic mess leading to SIGILL.

The kernel would need to have a scheduler that knows it can't use those cores for certain tasks. Think about how hard you would have to work to even identify such a task ...

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mmis1000 4 days ago | parent [-]

Current windows or linux executable format don't even list the used instruction though. And even it is listed, how about dynamic linkables? The program may decide to load library at any time it wishes, and the OS is not going to know what instruction may be used this time.

	▲	MBCook 3 days ago \| parent [-]
		You couldn’t even scan the executable if you wanted to. Because lots of code will check what the CPU is capable of doing and choose the most efficient path based on what instructions it’s allowed to use. So until you’ve run it (halting problem) you may find instructions that you’d never even run.