MREGS_ETHADDR
sbus_writeb(e[0], mregs + MREGS_ETHADDR);
sbus_writeb(e[1], mregs + MREGS_ETHADDR);
sbus_writeb(e[2], mregs + MREGS_ETHADDR);
sbus_writeb(e[3], mregs + MREGS_ETHADDR);
sbus_writeb(e[4], mregs + MREGS_ETHADDR);
sbus_writeb(e[5], mregs + MREGS_ETHADDR);