"off_t" and the return value is a "paddr_t" to allow mappings
at offsets past 2^31 bytes. Somewhat inspired by FreeBSD, which
only changed the offset to a "vm_offset_t".
Includes updates for the i386, pc532 and sh3 mmmmap from Jason Thorpe.
- the `alignment' and `boundary' arguments in bus_dmamem_alloc() only
serve as hints on how to break up a DMA transaction into chunks
when necessary; it is not necessary on sparc DVMA hardware.
- exclusively use the VM page size (i.e. PAGE_SIZE et.al.) when computing
resource allocations.
- remember the size of DVMA resource allocations in the private `_ds_sgsize'
field in a dma segment descriptor.
"BUS_SPACE_ALIGNED_POINTER()".
Equal to the param.h "ALIGNED_POINTER()" normally, but obeys additional
requirements of the bus_space_xxx_n() macros. (BUS_SPACE_DEBUG)
* In the bus tag structure, keep a reference to the parent bus.
* Express all bus space methods as inline functions in stead of macros
and use the parent bus tag reference to find the nearest "upstream"
bus that implements the method.