MECR_CIT
reg | MECR_CIT);
reg & ~MECR_CIT);
bus_space_write_4(iot, memctl_ioh, MEMCTL_MECR, MECR_CIT|MECR_NOS);
bus_space_write_4(iot, ioh, MEMCTL_MECR, MECR_NOS | MECR_CIT);
MECR_NOS | MECR_CIT);
MECR_NOS|MECR_CIT);