LDMA_MESSAGE_HEADER_SIZE
#define LDMA_MESSAGE_DLEN(msgsize) ((msgsize) - LDMA_MESSAGE_HEADER_SIZE)
#define LDMA_MESSAGE_SIZE(dlen) (LDMA_MESSAGE_HEADER_SIZE + P2ROUNDUP(dlen, 8))
if (len < LDMA_MESSAGE_HEADER_SIZE) {
if (buflen < LDMA_MESSAGE_HEADER_SIZE)