Changyuan Li contributed to both the u-root/u-root and tianocore/edk2 repositories, focusing on system programming and firmware development using Go and C. In u-root/u-root, Changyuan implemented ARM64 PEZ image handling to streamline Linux boot workflows, enabling extraction of raw images from compressed files during kexec operations. He also enhanced test reliability by integrating BusReader validation within virtual machine environments, improving CI coverage. In tianocore/edk2, Changyuan addressed a critical NULL pointer dereference in the UEFI CPU MP initialization path, adding robust parameter checks to prevent boot-time crashes and improve stability for uniprocessor guests, particularly under virtualization scenarios.