Ok so this means that calls accross compilation units always incur an indirection, right? Also I don't get how swapping the whole compilation unit can be achiev

Ok so this means that calls accross compilation units always incur an indirection, right? Also I don't get how swapping the whole compilation unit can be achieved atomically. A compilation unit might be composed by several functions. Where can I find more? I have tried to look in the literature but haven't found anything that reaches this level of detail.