OPB_MDM functionality

hi, this is my question:

Is opb_mdm used to load C code (from executable.elf) from SDRAM?. I
have downloaded an aplication (executable.elf) to the Sdram. Due to
the fault of a RS232 peripheral, I use opb_mdm as uart. This design
seems to work fine with xil_printf and standalone powerpc, but it
fails when I use printf or xilkernel. I have increased heap and stack,
but problem goes on. So I am thinking that it could be a interference
in opb_mdm functionality.

Could anyone tell me if it is possible?.

Regards