Why I can't boot uclinux kernal in NIOSＩＩ?

I give the final answer:

Actually, except the kernel project created and programmed into the flash, you

also need to create a root file system and program it into the flash. Please

follow the steps to create the kernel project and file system project according to

the "Linux Quick Start Guide". After build them successfully, open the NiosII

command shell and try to program both the ext_flash.flash and romfs.flash into

flash:

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elf2flash --base=0x00000000 --end=0x7fffff --reset=0x0 --input=vmlinux

--output=ext_flash.flash --boot

=$SOPC_KIT_NIOS2/components/altera_nios2/boot_loader_cfi.srec

nios2-flash-programmer --base=0x0000 ext_flash.flash

nios2-flash-programmer --base=0x0000 romfs.flash

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The ext_flash.flash is generated through the elf2flash command. The input file is

vmlinux.bin in the "build" folder under kernel project. The romfs.flash is

generated automatically after building the file system project. Please note to go

to the correct directory and input the commands.