When designing a Qsys system that contains Nios® II soft-core processor with a peripheral that has more than 32- bit address, Qsys will print out error message
"Address width above 32 bits are not supported for NIOS II"
Nios® II does not support address above the 32-bit range. As a result, Qsys cannot be generated.
To overcome this issue, it is recommended to use Address Span Extender IP from Altera. This IP can be used to expand address view of Nios® II or any 32-bit master beyond 4GB. Please note that 4GB is the maximum address window that can be provided by Address Span Extender IP.