SiFive brings open-source RISC-V chip architecture into prime time

This article is translated from Datacenterknowledge

In late October, two years after fabless semiconductor startup SiFive brought RISC-V open source chips to the industrial world with the launch of the HiFive Unleashed development board, the company announced a new product called HiFive Unmatched.

While the first development board illustrates the promise of the architecture, the latest Unmatched is a sign that RISC-V appears to be becoming the CPU of the PC, rather than an accelerator that plays the role of the CPU's assistant.     

SiFive isn't showing off this new product just for developers and enthusiasts. The Unmatched is a PC without the case. 

“I had to train myself not to say it’s like a PC; it actually is a PC,” SiFive CTO Yunsup Lee told DCK. “You can build your own PC and put it in a case, and that’s pretty cool.”

“We got a lot of input from different parties,” he added. “People told us they wanted more performance, more I/O and bandwidth. Also, they wanted it to be more of an industry-standard form factor so they could build other products on top of it.” 

The new motherboard is powered by SiFive's latest FU740 SoC, a five-core processor with four SiFive U74 64-bit application processor cores and one SiFive S7 core, and has 8GB of DDR4 memory and 32MB of Quad SPI Flash storage. It comes with slots for PCIe and NVMe cards, as well as slots for WiFi/Bluetooth modules. It also has adequate connectivity, with four USB 3.2 Gen 1 Type A and one MicroUSB port.

In fact, it’s getting close to prime time for RISC-V, which isn’t ready for mainstream adoption in data centers and servers, Lee said. “A lot of people and a lot of companies are working to put together the problems that need to be solved for these verticals. I think it’s going to be solved pretty quickly, probably within a year or two.”

RISC-V isn’t the only one who thinks it can make quick work of heavy lifting that’s traditionally limited to processors from Intel, AMD, and Arm. Chinese hyperscaler Alibaba has been investing heavily in the architecture, likely as a hedge against potential U.S. sanctions against Chinese companies. This summer, Alibaba unveiled the RISC-V-based XT910, a 16-core design that can reach up to 2.5 GHz and that the company claims is its most powerful RISC-V processor yet.     

Alibaba has said it plans to deploy the RISC-V ISA as the backbone of its cloud and edge computing infrastructure, although like Lee, the company acknowledged that it is "not mature enough in terms of technology and ecosystem."

Lee told us that he thinks the way ISA first enters the data center as a true CPU will be through internal applications at very large companies, powering custom computers built in-house to meet specific data center needs, and then into commodity servers.    

“I think it will happen soon, and once computers get into data centers, it’s more likely that people will start using RISC-V,” he said. 

“Obviously there are other forces that are accelerating the adoption of RISC-V,” he added, citing Nvidia’s pending acquisition of Arm and concerns about the U.S. restricting certain technology exports. 

“I think these types of external factors are definitely helping to accelerate the adoption of RISC-V in a variety of markets, not just the data center,” he said.