mdb-bhyve should lookup against private symbols
When using mdb-bhyve against an instance, it's possible to associate symbols with address ranges using
::nmadd. These go into a "private" table, not associated with any object files (relevant since mdb-bhyve is acting on guest memory with no notion of objects). Despite these private symbols existing in the mdb session, they are not used by actions such as
$C, when attempting to resolve symbols for a given program counter address. This is because the
t_lookup_by_addr hook in mdb-bhyve is a no-op:
.t_lookup_by_addr = (int (*)()) mdb_tgt_notsup,
This could be updated to use the private symbol list, allowing for a wider range of debugging possibilities.