dmac_laddress specifies a 64-bit I/O address appropriate for programming the device's DMA engine. If a device has a 64-bit DMA address register a driver should use this field to program the DMA engine.
dmac_address specifies a 32-bit I/O address. It should be used for devices that have a 32-bit DMA address register. The I/O address range that the device can address and other DMA attributes have to be specified
in a ddi_dma_attr(9S) structure.
dmac_size describes the length of the transfer in bytes.
dmac_type contains bus-specific type bits, if appropriate. For example, a device on a PCI bus has PCI address modifier bits placed here.