Arduino for STM32

Thanks, I try this later

I am going to use 2 serial ports in my STM32F103C8 project. My development environment is Windows 10, Arduino IDE 1.8.15, Arduino_Core_STM32 2.0.0

My testing code is:
void setup() {
Serial1.begin(115200);
Serial2.begin(115200);
}

void loop() {
}

build_opt.h
-DENABLE_HWSERIAL2

I got compilation ...

I am Jason, a beginner of stm32duino. I am working on a STM32F103C8 from taobao with different types of sensors.