OK, I see you made each one a separate feature bit, which does allow this
somewhat. But you can't just change the meaning arbitrarily, all you can
do is refuse to supply some of them. This is because virtio is an ABI,
but also it's plain sanity: run a new guest on an old host and get crazy
Two more questions:
I assume memtot should be equal to the initial memory granted to the guest
(perhaps reduced if the guest can't use all the memory for internal reasons)?
I'm not sure of the relevance to the host of the number of anonymous pages?
That's why I wondered if unswappable pages would be a better number to supply?