rubbish out of uart in multiprocessor design

I've got a design with two nios2 cpus which have a uart component and the jtag uart on cpu1. At present I'm just sending some data from cpu2 to cpu1 via shared memory and a mutex. When cpu1 gets the data it writes it to stdout. When I hook up the jtag uart to stdout by checking a box in system library, everything works. However, if instead I hook up the uart to stdout, garbage comes out of the serial port. I've tried moving the uart component address in SOPC Builder, explicitly opening /dev/uart1 and writing to the file instead of using stdout; nothing works, I still get garbage out of the uart. Before making my two-cpu design I had studied the multiprocessor tutorial and got it working. So, I went back to the multiprocessor tutorial and hooked up the uart to stdin/stdout/stderr in place of the jtag uart; this also results in rubbish out of the uart. However, if I hook up the uart as stdin/stdout on a design with a single nios2 cpu, the uart works properly.