In message <3586C79C.FCDA6E5D@mclink.it>, Dante Profeta writes:
>
>bus_dmamem_alloc();
>bus_dmamem_map();
>bus_dmamap_create();
>bus_dmamap_load();
>
>Could you please describe them briefly?

BUS_DMA(9)                   NetBSD Kernel Manual                   BUS_DMA(9)

NAME
     bus_dma, bus_dmamap_create, bus_dmamap_destroy, bus_dmamap_load,
     bus_dmamap_load_mbuf, bus_dmamap_load_uio, bus_dmamap_load_raw,
     bus_dmamap_unload, bus_dmamap_sync, bus_dmamem_alloc, bus_dmamem_free,
     bus_dmamem_map, bus_dmamem_unmap, bus_dmamem_mmap - Bus and Machine Inde-
     pendent DMA Mapping Interface

...

If you've already read the manual, and still have questions, that's
entirely different. :)