Hello,
The most important is to take care that the executables will not overlap in the flash memory regions. For that reason you will make a rough estimation about how much space they are going to consume and in the SOPC builder or QSYS you will leave the proper space between them. A very nice reference to read about that is in the tutorial
(tt_nios2_multiprocessor_tutorial.pdf). Check at page 1-9 the paragraph
software design considerations for multiple processors I think the tutorial will solve all your questions. If not, come back here to see it in more detail.
