- Mark that it cannot handle greater than 4GB of RAM at this time. Fixing
that will come later. Fail any attempts to dump above thati limit.
- If a call to aac_disk_dump() needs to be split into multiple i/o's,
increment the virtual offset after each i/o instead of just dumping the
same offset over and over again.
- Bail out if bus_dmamap_load() returns an error. Error recovery is likely
not possible.