@kenshirriff I remember some beyond useless support person at Intel telling us at VMware that the Pentium did not use microcode when we were trying to find out about a bug that appeared to have a microcode fix that some but not all OEMs had released. OK well we've reversed engineered part of the update for the microcode your processors don't have, so maybe we could talk to somebody more senior?... (eventually got to senior engineering folks who were helpful)