> as soon as you've switched to 64 bit mode, you can ignore all legacy stuff. That, I assume, is the point. If it isn't used by the vast majority why spend the

> as soon as you've switched to 64 bit mode, you can ignore all legacy stuff. That, I assume, is the point. If it isn't used by the vast majority why spend the silicon keeping it present? > all the 16/32 bit mode stuff is all 'emulated' with microcode That microcode still needs to be maintained, tested, & verified, with each chip iteration, so it is more than just a tiny bit of silicon that could be repurposed. > and you can leave it there forever If it is there it will be expected to work (otherwise why keep it?) and they need to keep verifying that containment. I'm not much of a hardware guy myself so maybe the risk profile is different - but I've tripped over, or been mugged by, so-called dead code that ends up having “interesting” side effects, enough times for me to not want a bunch of it in my CPU's design if it is avoidable. Removing it has costs somewhere of course, both in Intel's design work and potential compatibility issues in minority use cases. But deciding to leave it in has costs elsewhere, so the options & risks need to be looked into in either case.