> When an invalid instruction exception occurs, it is very easy to identify whether the invalid instruction was an AVX-512 instruction, because those start with a prefix different from any other instructions.
You're missing the point: the processes executing AVX-512 do not have any particularly strong requirement for AVX-512 instructions, they're just optimistically using them to improve performance because CPUID claimed they were supported. It would be pathologically bad behavior to control scheduling behavior with this, because in practice it would result in things like glibc deciding to use AVX-512 for string functions resulting in every program that uses memcpy (i.e. every program) not being allowed to be scheduled on the little cores.
You're missing the point: the processes executing AVX-512 do not have any particularly strong requirement for AVX-512 instructions, they're just optimistically using them to improve performance because CPUID claimed they were supported. It would be pathologically bad behavior to control scheduling behavior with this, because in practice it would result in things like glibc deciding to use AVX-512 for string functions resulting in every program that uses memcpy (i.e. every program) not being allowed to be scheduled on the little cores.