[RISCV/Chisel]Error: unrecognized opcode vsetvli

Situation

I'm Implementing RISCV vector instructions with chisel.

When adding the vsetvli instruction, the above compilation error occurs.

Cause and solution

The argument at compile time was incorrect.

　Incorrect:

riscv64-unknown-elf-gcc　-march=rv32i

　Correct:

riscv64-unknown-elf-gcc　-march=rv32iv

It seems that the ones with v correspond to vector instructions.

For details, see the page below

https://gcc.gnu.org/onlinedocs/gcc/ RISC-V-Options.html