RISC-V International has released a number of new specifications that enhance the RISC-V ecosystems. I talked with Chief Technology Officer for RISC-V International, Mark Himelstein, about their latest specifications. This includes E-Trace, the Supervisor Binary Interface (SBI) specification, and the UEFI specification.
Himelstein also discusses the RISC-V Zmmul extension. He noted, “Zmmul was very interesting because it was targeted by the embedded folks. They championed it. Our original multiplier also had divide with it and it had multiply and divide. They said, ‘we don’t want to use too much chip space.'” The Zmmul provides multiplication support without the divide overhead. This doesn’t change the instruction set; it only defines an implementation that doesn’t include the divide support, only the multiply.