VAC_DP_BUFBYTES
if (blk > VAC_DP_BUFBYTES)
blk = VAC_DP_BUFBYTES;
sc->sc_dpstage = kmem_alloc(VAC_DP_BUFBYTES, KM_SLEEP);
#define VAC_DP_BUF1 (VAC_DP_BUF0 + VAC_DP_BUFBYTES) /* 0x7f0 */