SiFive - August 18, 2022

SiFive's RISC-V Leadership Strengthens with New Vector Solutions

With the 2021 launch of the SiFive® Intelligence™ X280, SiFive was the first company to release a RISC-V Vector 1.0 product, and it took the market by storm. The X280 has quickly achieved market-leading success, with design wins across a number of high performance applications including AI inference, Image Processing, and Datacenter applications. Customers include a U.S. government agency working on next generation aerospace/defense standards, a tier #1 global mobile image processor supplier, and a tier #1 global hyperscaler for AI, and the list grows daily..

With the latest release of the SiFive Intelligence X280, SiFive has several exciting new first-to-market features including:

  • Vector Coprocessor interface: This innovative vector coprocessor accelerator interface enables better power and area efficiency with easier-to-program solutions.

  • Multi-cluster: The X280 now offers a coherent core complex of up to 4 clusters of 4-cores that scales to best-in-class multi-TOP performance. WorldGuard: A hardware system security solution bringing trusted execution to protect AI/ML algorithms.

  • Reference Platform: Introduction of the first X280 Reference Platform for reducing time-to-market for developers and the fast-growing RISC-V ecosystem

The Vector Coprocessor Interface extension (VCIX) solves two of the biggest challenges facing designers; system complexity and ease of programming:

  • To reduce overall system complexity, VCIX enables designers to directly connect their own custom accelerator to the X280, utilizing and sharing the X280 processor system resources. This results in a far simpler, and more efficient, accelerator system design.

  • In order to solve the challenge of ease of programmability, VCIX enables a single toolchain to be used for programming both the X280 and the custom accelerator. As VCIX is a vector instruction-mapped interface, it gives a direct connection from the X280 vector ALU to a custom accelerator. This enables custom vector instructions to be executed on the accelerator directly from the vector pipeline as part of the standard SiFive software flow.

Being able to share many of the fundamental processor resources, such as the vector register bank, main processor caching architecture, and memory system, brings many benefits:

  • Improved the time to market due to the reduced design time for custom accelerators

  • Higher system performance for specialized workloads* Better area optimization resulting in power and area efficiency gains

Multi-core, Multi-cluster

The X280 is the first RISC-V Vector processor that can be configured up to 16 cores in a coherent multi-cluster Core Complex, consisting of up to 4 cores in a coherent multi-core cluster and up to 4 coherent clusters. With these multi-core, multi-cluster configurations, SiFive also delivers the complete, configured fabric infrastructure alongside the processor to enable full coherency.


WorldGuard, now available for the first time in a high core count system, provides a simple, yet powerful, way of enforcing hardware security by isolating code and data as well as preventing access to select peripherals. It allows different assets to be isolated into separate security worlds. This additional layer of protection can prevent rogue or bogus software running at any RISC-V privilege level, including Machine Mode, from accessing confidential data or tampering with the software. This allows sensitive firmware, like a home-grown AI/ML stack, to be isolated from more open software and also from intrusion by debug and trace capabilities.

X280 Reference Platform

This new resource enables easy and fast access to everything needed by SiFive customers and ecosystem partners to develop hardware and software that leverages all of the new capabilities in this latest release of the X280. The X280 Reference Platform (available in Q3) will comprise of a hardware target based on the Xilinx VCU118 FPGA board, a functional model target based on QEMU (and matching the FPGA hardware target), and a Linux-based BSP, as well as the full architectural specification of the platform. The X280 Reference Platform is intended to be easy to use by developers and the software ecosystem alike, making it easier than ever to get your application up and running with a real RISC-V vector-enabled platform.

With the latest version of the X280, designers will continue to benefit from the success trajectory of SiFive vector processor designs, taking RISC-V and RISC-V Vectors further into new and exciting marketing applications.

For more information about SiFive vector solutions, visit For more information about the SiFive Intelligence X280 visit