> Um, what? To have a data race you need a formal model that doesn't exist for the hardware. Intel and other manufacturers do provide a model for their hardwar

> Um, what? To have a data race you need a formal model that doesn't exist for the hardware. Intel and other manufacturers do provide a model for their hardware (although it is a relatively recent thing and has been formalized outside of intel). > When they say "Undefined" they really meant it, C++ UB is allowed to do MMIO, or whatever else. Well, I do give you that.