LDC_PKT_PAYLOAD
if (len > tx_avail * LDC_PKT_PAYLOAD) {
lp->env = uimin(len, LDC_PKT_PAYLOAD);
if (len <= LDC_PKT_PAYLOAD)
bcopy(p, &lp->major, uimin(len, LDC_PKT_PAYLOAD));
p += uimin(len, LDC_PKT_PAYLOAD);
len -= uimin(len, LDC_PKT_PAYLOAD);