Editorial: RISC-V Is The New AI

AI-chip startups raised billions of dollars in prior years, but this year investors turned their attention to RISC-V startups. The new instruction set faces both technical and business challenges.

Linley Gwennap

There’s a new kid in town, and everybody’s talking. Over the past several years, venture-capital firms have poured billions of dollars into AI-chip startups, with little to show for it. Suddenly, those startups are finding it difficult to raise new capital. Instead, money is flowing into RISC-V startups, seeking a return from the popular open-source instruction set (ISA).

Investors see a bull market for RISC-V. Most large processor and system-on-chip (SoC) vendors have adopted the technology. RISC-V International has more than 3,800 members, and the consortium claims members have shipped chips containing a total of 10 billion RISC-V cores. (Note that most RISC-V users don’t report shipments, so this number is impossible to verify.) Most of these cores perform low-level management and other simple functions, but CPU vendors such as Andes and SiFive offer more-powerful designs suitable for complex workloads.

RISC-V offers significant advantages over Arm. The open-source ISA is available without license fees to anyone, whereas a license to design Arm-compatible CPUs is rarely offered and costs millions of dollars. Arm generally forbids any modification of its predefined instruction set, whereas RISC-V users are free to innovate by creating new instructions.

RISC-V vendors frequently tout these advantages, but a deeper analysis discloses holes in the story. The greatest concern for investors is that only a small portion of the billions of RISC-V cores generate any revenue for RISC-V vendors. Most of these shipments are from companies such as AMD, Nvidia, Qualcomm, and Western Digital that design their own CPUs and therefore pay no license fees. The only major companies publicly known to be shipping chips containing licensed RISC-V cores are MediaTek and Renesas, both of which source from Andes. As an indication of this challenge, SiFive recently laid off 20% of its workforce.