Thanks to everyone who replied. I appreciate your time to help
educate me.

It works because the 82xx is cache coherent.  The MMU mapping
is irrelevant.  

That is the missing piece of the puzzle. I had worked with the 860
before and this was an issue. It hadn't occurred to me that the 82xx
was different.

There is no bug here.  Just because people don't
understand how something works doesn't mean there is a bug
present.  

The reason I asked the question in the first place was because I didn't
understand how it could work.  I now understand it and can rest easier.

Thanks,
Conor