The NES incorporated a chipset that buried an entire 6502 inside. You can get a Rockchip ARM chip for the price of a pizza that incorporates mixed cores on the die. Maybe the chipmakers don't NEED to solve every edge case until the end of time, but delegate side channel attack mitigations like this back to the chipgobblers (us).

Hear me out: Instead of making SMT an all-or-nothing pre oposition, we have "lousy cores" where untrusted code goes and make the customer "prove" it should get elevation to the cores with SMT?

I dont't want to clobber my chip that's running the mega-important payroll jobs where no one can load anything else on to the board under pain of death. However I would like to be forced into tagging what is safe to run SMT else I get stuck on the safer cores.

I might be an intern who has no idea what any of this stuff means and goes to Google it, then learn what this attack vector truly is. Then makes a plan on how to defend against it.

Am I crazy?