stack problem (printf?)

[Altera_Forum]

I have some problems with a custom board and software.  

It seams that the stack get&#39;s destroyed, when I use the printf function. I don&#39;t know if printf is really the problem. Always if i change something, it works or it works not ! I could not produce the error on the cyclone dev. board. I could reduce my software to a small testprogram, which fills a testbuffer (srcbuff)  in global memory, copies it then onto the stack (dstbuff) , calls printf and  compares afterwards the two buffers.  some system properties: - quartus 5.0 Nios 5.0 - NiosII/s (2k instruction cache) - 1k onchip memory (exception address 0x00000020) - external sram 0x800000-0x87FFFF - reduced device drivers (jtag uart should use no interrupt) - no os  the following testprogram works if  - dstbuff is global (not on stack) or - printf is used (but interrupts are disabled during call to printf) or  - printf is replaced by iprintf or  - printf No.2 is used instead of printf No.1  if the program is like below, dstbuff is on stack,interrupts are enabled, then i get error e.g.  ... Hello from Nios II! TESTCOUNT:00000 +++ ERROR dstbuff first diff index :32764 at 0x00814008 srcbuff:60 first diff index :32764 at 0x0087FFE0 dstbuff:E4 ...  # include <stdio.h># include <stdlib.h># include <string.h># include <time.h># include <alt_types.h># include <unistd.h># include "sys/alt_irq.h"# include"system.h" # define BYTE unsigned char # define BUFFSIZE 32768  BYTE srcbuff[BUFFSIZE]; // BYTE dstbuff[BUFFSIZE]; int fill_testbuffer(BYTE *buffer,int count);   alt_irq_context irqcontext;  int main() {  BYTE dstbuff[BUFFSIZE];  int testcount=0;  int i;    printf("Hello from Nios II!\n");   // irqcontext=alt_irq_disable_all();    while(1) {  fill_testbuffer(srcbuff,BUFFSIZE);  memcpy(dstbuff,srcbuff,BUFFSIZE); // irqcontext=alt_irq_disable_all();  printf("TESTCOUNT:%05d\r\n",testcount++); // PRINTF No.1 // printf("CLOCK:%06d TESTCOUNT:%05d\r\n",(int)clock(),testcount++); // PRINTF No.2 // alt_irq_enable_all(irqcontext);  if(memcmp(srcbuff,dstbuff,BUFFSIZE)) {  for(i=0;i<BUFFSIZE;i++) {  if(srcbuff!=dstbuff) {  printf("+++ ERROR dstbuff\r\n");  printf("first diff index :%d at 0x%08X srcbuff:%02X\r\n",i,(int)&srcbuff,srcbuff);  printf("first diff index :%d at 0x%08X dstbuff:%02X\r\n",i,(int)&dstbuff,dstbuff);  break;  }  }  while(1);  }  }   return 0; }  int fill_testbuffer(BYTE *buffer,int count) {  int i;  unsigned int seed;  seed=clock();  srand(seed);  for(i=0;i<count;i++) {  buffer[i]=rand();  }  return 0; }   any ideas ? thanks