struct resource question

[Chuck Tuffli]

There is an aspect of struct resource (src/sys/sys/rman.h) that I'm
tempted to change but I wanted a) to get a sense from others if this
is worth changing and b) find out what kind of changes others would
like to see.
Resources are allocated/managed generically, but there needs to be an
association between a resource structure and some resource specific
information (like bus tags). Currently, this association is done by
adding "non-generic" parts (r_virtual, r_bustag, r_bushandle) to the
resource structure itself. The MSI code will add yet another resource
specific variable to this structure. This feels "wrong",  but I'm
wondering if this is wrong enough to need fixing. Thoughts?
---chuck