help ！！ undefined reference to `main' error

Info: Linking tse1_sw.elf

nios2-elf-g++ -T'../tse1_sw_bsp//linker.x' -msys-crt0='../tse1_sw_bsp//obj/HAL/src/crt0.o' -msys-lib=hal_bsp -L../tse1_sw_bsp/ -L./ -Wl,-Map=tse1_sw.map -O0 -g -Wall -EL -mno-hw-div -mhw-mul -mno-hw-mulx -o tse1_sw.elf -lm

../tse1_sw_bsp/\libhal_bsp.a(alt_main.o): In function `alt_main':

C:\altera\12.0sp2\kits\cycloneVGX_5cgxfc7df31es_fpga\examples\board_update_portal\software\tse1_sw_bsp/HAL/src/alt_main.c:154: undefined reference to `main'

collect2: ld returned 1 exit status

make: *** [tse1_sw.elf] Error 1