Cannot access memory at address xxx, stack overflow management ?

Hi Cris and sorry for replying late,

My project is based on a NiosII (fast, debug level1) hosted on Cyclone III on a custom board :

- The nios program / fpga firmware is stored in external flash (EPCS16)

- The code is executed in external 2MegaBytes sram (cypress cy7c1380d)

- Nios purpose is to manage external devices with SPI (2 SPI lines)

- A push&rotary button is used to modify some parameters used in SPI communications (it generates interruptions)

- these parameters are display on a LCD (onchip memory is used as a buffer between nios and LCD driver (vhdl))

- these parameters are stored in an external non-volatile memory (SPI FRAM)

A timer is used to manage parameters: update (if button interruption appends before), spi sending and display.

Most of the variable are global. The display routine is written is c++ and is quite complicated (I didn't wrote it, many vectors and objects are used to create the font and write the buffer). I have maid some tests with only the display routine in my nios, but there I didn't really find anything. The nios is more stable but I have 1 time the "cannot access..." error. So at the moment I am focused on hardware problems like checking sram timing (address setup&hold times)...

Do you know what is the exact meaning of "Cannot access memory at address" ?

Does it mean that the address is not reachable (hardware problem) or that the memory content is corrupted/not the one expected... ?

thanks again.