There is an #include "opt_iobzclock.h" missing, in ioblix_zbus.c. This header file contains your IOBZCLOCK define. So if you commit the changes, please include this line.
Ah, makes sense.
Then, the baud rate set had to be four times the desired baud rate - to communicate with another 9600 baud port I had to set the baud to 38400.And this problem was still present after you had set IOBZCLOCK directly in ioblix_zbus.c ?
Yes. Before setting it, I couldn't get any meaningful characters across the serial link because, I'm assuming, the baud rate wasn't correct.
Thanks, John