The struggle between abstraction, technical accuracy, and aesthetics. I find the whole thing depressing, no matter which comes out ahead.
Anyway, you can see here my attempt to depict the HVM emulated devices. It's a slightly-simplified (and dramatically-changed) version of a diagram in http://www.cmg.org/measureit/issues/mit41/m_41_1.html . (I think mine is more attractive and clearer, but theirs is most assuredly more complete.) The biggest difference between this one and that is that I've focused on the write/interrupt aspect as a cycle, ordering the other elements based on that interaction with the devices. Hence the overall circular aspect. I think the concept is good, but the implementation could use some work. The big aesthetic problem with this diagram is that it wastes a huge amount of space in the "emulated device" box, because that box needs to span the entire circle. Maybe I'll revise it later.
Most likely we won't include anything like this in the book. But I did rough it into earlier drafts, so it's good to at least get something in there.
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