Odd nios2-download verify fail between address issue, on-chip memory

xxiang, are you using an SDC file and checking for timing closure?

If you raise the cache size too much it's possible that timing won't be met because internal memory is already placed on the device, and routing to all the memory blocks needed for your processor cache may decrease the Fmax of your processor and system.

Timing problems may lead to "verify failed" errors.