SBus Example

A DMA engine on an SBus in a SPARC machine has the following attributes:

• Access to addresses ranging from 0xFF000000 to 0xFFFFFFFF only

• 32-bit DMA counter register

• Ability to handle byte-aligned transfers

• Support for 1-byte, 2-byte, and 4-byte burst sizes

• Minimum effective transfer size of 1 byte

• 32-bit address register

• No scatter-gather list

• Operation on sectors only, for example, a disk

A DMA engine on an SBus in a SPARC machine has the following attribute structure:

static ddi_dma_attr_t attributes = {
    DMA_ATTR_V0,   /* Version number */
    0xFF000000,    /* low address */
    0xFFFFFFFF,    /* high address */
    0xFFFFFFFF,    /* counter register max */
    1,             /* byte alignment */
    0x7,           /* burst sizes: 0x1 | 0x2 | 0x4 */
    0x1,           /* minimum transfer size */
    0xFFFFFFFF,    /* max transfer size */
    0xFFFFFFFF,    /* address register max */
    1,             /* no scatter-gather */
    512,           /* device operates on sectors */
    0,             /* attr flag: set to 0 */
};