$ ./riscv32-elf-gcc ~/a.c
/home/renxiuhu/opt/risc-v/nds32le-elf-mculib-v5f/bin/../lib/gcc/riscv32-elf/10.4.0/../../../../riscv32-elf/bin/ld: /home/renxiuhu/opt/risc-v/nds32le-elf-mculib-v5f/bin/../lib/gcc/riscv32-elf/10.4.0/../../../../riscv32-elf/lib/crt0.o: in function `.L0 ':
(.text+0x52): undefined reference to `main'
collect2: error: ld returned 1 exit status