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RISC-V Announces First New Specifications of 2022, Adding to 16 Ratified in 2021 | RISC-V International

Efficient Trace, Supervisor Binary Interface, Unified Extensible Firmware Interface, and Zmmul Multiply-Only Extension Accelerate Embedded- and Large-System Design.

Six Additional Specifications Already In the Pipeline As Development Extends Into Vertical Applications.


Nuremberg, Germany – June 21, 2022RISC-V International, the global open-design standards pioneer, announced its first four specification and extension approvals of 2022 – Efficient Trace for RISC-V (E-Trace), RISC-V Supervisor Binary Interface (SBI), RISC-V Unified Extensible Firmware Interface (UEFI) specifications, and the RISC-V Zmmul multiply-only extension. The news builds on momentum from 2021, in which 16 specifications representing more than 40 extensions were ratified. 

“The RISC-V culture of contribution and collaboration continues to produce impressive and strategic results,” said Calista Redmond, CEO of RISC-V. “RISC-V members are leaders in the era of open compute, proving that collaboration accelerates innovation through shared investment while growing global opportunity.”

“These new specifications accelerate embedded and large-system design,” said Mark Himelstein, CTO of RISC-V. “Debugging is one of the hardest things to do on a chip,” he explained. “E-Trace for RISC-V creates a standard way to do processor trace that’s extremely efficient and is especially useful in embedded system design.”

  • E-Trace for RISC-V defines a highly efficient approach to processor tracing that uses a branch trace, ideal for debugging any type of application from tiny embedded designs to super powerful computers. E-Trace for RISC-V documentation specifies the signals between the RISC-V core and the encoder (or ingress port), a compressed branch trace algorithm, and a packet format to encapsulate compressed branch trace information. Development and ratification of this specification was led by Gajinder Panesar of Picocom and RISC-V’s E-Trace Task Group.

“RISC-V SBI offers developers a similarly critical resource,” Himelstein added. “The ability to port supervisor-mode software across all RISC-V implementations, essentially allowing developers to write something once and apply it everywhere.”

  • RISC-V specification for SBI architects a firmware layer between the hardware platform and the operating system kernel using  an application binary interface in supervisor mode (S-mode or VS-mode).  This abstraction enables common platform services  across all RISC-V operating system  implementations. Many RISC-V members have already implemented the RISC-V SBI specification in their RISC-V solutions, so ratifying the specification will ensure a standard approach across the entire RISC-V ecosystem, ensuring compatibility. Development and ratification of this specification were led by Atish Patra of Rivos, with work conducted in the Platform Horizontal Steering Committee. 

“UEFI is a critical element of any system,” said Himelstein, “In some applications, it may replace basic BIOS software.”

  • RISC-V UEFI Protocols bring existing UEFI standards onto RISC-V platforms. Development and ratification of this specification were led by Sunil V L, Ventana Micro and Philipp Tomsich, VRULL GmbH, with work conducted in the Privileged Software Technical Working Group. 

“For many microcontroller applications, division operations are too infrequent to justify the cost of divider hardware,” explained Himelstein. “The RISC-V Zmmul extension will benefit simple FPGA soft cores in particular.”

  • RISC-V Zmmul Multiply Only enables low-cost implementations that require multiplication operations but not division, and is part of the RISC-V Unprivileged Specification. Development and ratification of this extension were led by Allen Baum, with work conducted in the Unprivileged ISA Committee. 

RISC-V announced the ratifications at Embedded World here, where RISC-V is the focus of several talks. RISC-V International is also hosting a pavilion of member-company innovations in the exhibition hall through June 23rd. Showcase participants include Andes Technology; CAES, Cobham Gaisler; Canonical Ubuntu; Codasip; Codeplay; Digital Core Technologies; GreenWave Technologies; Imperas; OpenHW Group; SiFive; Syntacore and Ventana Micro Systems.

About RISC-V International

RISC-V International is the non-profit home of the open standard RISC-V Instruction Set Architecture (ISA), related specifications, and stakeholder community. More than 2,800 RISC-V members across 70 countries contribute and collaborate to define RISC-V open specifications as well as convene and govern related technical, industry, domain, and special interest groups. RISC-V combines a modular technical approach with an open, royalty-free license model — meaning that anyone, anywhere can benefit from the IP contributed and produced by RISC-V. RISC-V enables the community to share technical investment, contribute to the strategic future, create more rapidly, enjoy unprecedented design freedom, and substantially reduce the cost of innovation. To learn more, visit


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