I am running a lwip with vdk project on BF527 processor on my custom board. After ethernet communication is established there are some multiple function calls (nested functions). In one of the function call the code goes into exception, excause = 0x21 (undefined instruction) and RETX= 0x00000002. I am using external memory sdram (64MB), with cache enabled. I could not understand how/why the code is going to this location (RETX= 0x00000002) which may be causing this exception? Please advise.