Author here: Actually, the slide 'no publically available simulator implements this correctly' is somewhat misleading (it had a follow up slide that I cut and replaced by verbal comments - I should re-add it to the PDF). What I meant is that the entire mechanism (Task switching, page fault handling, etc.) is not implemented correctly on any sim, i.e. you have subtly different behavior. This was quite a challenge in debugging this in the first place, so I actually wrote the code to work around any bochs quirks I encountered -- just so that I have a debug environment.