Only need add follow line into platformio.ini
platform_packages = framework-arduino-gd32v @ https://github.com/sipeed/Longduino.gitAdd follow url into Boards Manager URLs.
http://bigbits.oss-cn-qingdao.aliyuncs.com/Arduino_for_GD32V/package_longduino_index.json
See Todo list.