There was (I think probably still is) a qemu bug with JSON. It accepted requests to read guest memory in JSON format, with the memory addresses encoded as JSON numbers.
When reading out guest kernel memory (addresses are at the top of 64 bit space) these would silently be rounded to the nearest whole double. It took me a very long time to understand what was going on.
When reading out guest kernel memory (addresses are at the top of 64 bit space) these would silently be rounded to the nearest whole double. It took me a very long time to understand what was going on.