SDRAM problem in SOPC builder

The nios's call (and jump) instruction encodings only have 26bits for the target address (the least significant bits are always zero) so a direct call (ie not through a register) cannot cross a 28bit boundary as the high 4 address bits aren't changed.

Without special code (which could, in theory, be added by the compiler or linker) this limits a program to 256MB. Within Linux (or similar) it will also stop shared libraries being loaded with code crossing a 256MB boundary).

To get the warning you must either have instruction memory in more than one 256M block of address space - eg more than 256M of DRAM or DRAM and internal code memory.

This warning itself can be ignored, but you have have to use function pointers if you need to call between the code areas. The linker will error these attempts.