In drivers/serial/8250.c:995 it reads: if (!up->port.iobase && !up->port.mapbase && !up->port.membase) return; As you can see the test !up->port.mapbase is duplicated, which makes no sense. maybe a different test was intended here? also since membase is a pointer shouldn't the '&&' be replaced with '||'? thanks, Roel - To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html