How to set Virtual Memory Address for excalibur with mmu?

Hello everyone.

The NiosII MMU boot mechanism puzzle me for several days.

With MMU,elf can be converted to the hex with virtual address by adding the mmu module.but I use the command elf2hex with this error:

$ elf2hex --input=nios2_germs_monitor.elf --base=0xd0004000 --end
=0xd0004800 --width=32 --output=memory_monitor_.hex
Exception in thread "main" java.lang.IllegalArgumentException: Data base address
 must be positive
        at com.altera.memory.ConcatinatingMemory.add(ConcatinatingMemory.java:32
)
        at com.altera.memory.ELFMemory.read(ELFMemory.java:152)
        at com.altera.memory.ELFMemory.read(ELFMemory.java:92)
        at com.altera.elf2hex.Elf2hex.<init>(Elf2hex.java:111)
        at com.altera.elf2hex.Elf2hex.main(Elf2hex.java:52)

Could anyone give me some clue?

Kinder Regards!