MAX_SCSI_XFER
#define MAX_DMA_SZ MAX_SCSI_XFER
sc->sc_maxxfer = MAX_SCSI_XFER;
.scsi_max_xfer = MAX_SCSI_XFER,
.scsi_dma_segs = (MAX_SCSI_XFER / 4096),
.scsi_max_xfer = MAX_SCSI_XFER,
.scsi_dma_segs = (MAX_SCSI_XFER / 8192),