RISC-V’s Supervisor Binary Interface “SBI” is the interface between the platform-specific firmware and the running operating system or hypervisor for interacting with the supervisor execution environment in the higher privileged mode. The Linux kernel has been working to support a newer version of the SBI that is more extensible moving forward.
article: https://www.phoronix.com/scan.php?page=news_item&px=RISC-V-Linux-SBI-v0.2-Continues