Advanced Configuration and Power Interface Specification

Device Configuration
For example, if a platform implements a PCI bus that cannot access all of physical memory, it has a
_DMA object under that PCI bus that describes the ranges of physical memory that can be accessed
by devices on that bus.
A _DMA object is not meant to describe any “map register” hardware that is set up for each DMA
transaction. It is meant only to describe the DMA properties of a bus that cannot be changed without
reevaluating the _SRS method.
Arguments:
None
Return Value:
A Buffer containing a resource descriptor byte stream
_DMA Example ASL:
270 Hewlett-Packard/Intel/Microsoft/Phoenix/Toshiba