This article is part of the TechXchange: RISC-V: The Instruction-Set Alternative.
SiFive, a startup designing CPU cores based on the open RISC-V architecture, has raised $175 million in its latest funding round, elevating its valuation to more than $2.5 billion as it prepares for a potential IPO.
The Silicon Valley company said the round will give it more financial firepower to take on Arm’s dominance in the market for high-performance CPU cores used throughout the semiconductor world. The startup said it plans to use funds to staff up and accelerate the development of its most advanced RISC-V cores for data centers and other markets. The Series F round was led by Coatue Management.
“The market has spoken and made it abundantly clear that RISC-V computing will be competing for the heart of all future computing platforms,” said CEO Patrick Little in a statement. "Our customers are signaling strong demand for SiFive to deliver the highest level of performance as quickly as possible.”
It's SiFive or Arm
SiFive was founded back in 2015 by three of the University of California, Berkeley, researchers that developed RISC-V, the open-source instruction set architecture (ISA) at the heart of SiFive's designs.
While RISC-V is an open standard, SiFive is building a growing business out of designing RISC-V CPU cores and offering them to other firms, which combine them with other IP in systems on a chip (SoCs). That pits it directly against Arm, whose CPU cores are at the heart of most of the world's smartphones and embedded devices. Arm is also expanding into markets such as data centers SiFive is also eyeing.
"At the end of every design win, it's typically SiFive or it's Arm," said Little in a briefing with reporters and analysts. "There is nothing in the architecture that would prohibit [RISC-V] from being at the center of any processing capability, from the data center to the edge to automotive."
To date, the company has raised more than $350 million in venture funding to build its core business. That has turned it into one of the most richly financed startups in the once-overlooked chip industry.
SiFive also announced that it is unloading its OpenFive business unit to Alphawave for $210 million, giving it additional funds to pour into product development. SiFive plans to close the deal by late 2022.
“If we’re going to move fast, we also have to be very focused,” said Little, adding that the company also is divesting a range of intellectual property unrelated to its core RISC-V designs in the deal, including connectivity IP.
SiFive has raised funding from a wide swath of companies in the semiconductor market, including the venture capital arms of AMD (through Xilinx Ventures), Intel, Qualcomm, and Samsung Electronics.
“They are starting to realize that RISC-V is becoming one of the key ISAs in the industry,” Little told Electronic Design, adding it has also partnered with all of the top foundries, including Intel and TSMC.
Other investors include Spark Capital and Sutter Hill Ventures, as well as SK Hynix and Western Digital.
Driving Up Performance
Little said the plan is to keep introducing more advanced cores with better performance per watt so that it can eventually compete on a more equal footing with Arm.
SiFive has rolled out launched three new products in its flagship "Performance" processor family in the last year alone. Little said the high-performance CPU core it rolled out in the first half of 2021—the P550—pumps out the same level of performance as Arm's Cortex-A75 core at 30% less power while taking up roughly 50% less area on the die. The P550 will be used in processors coming to market later in 2022.
The RISC-V core it introduced in the second half last year—the P650—adds 40% more performance on top of its previous generation, giving it comparable performance Arm's Cortex-A77, which was first used in mobile chips in 2020. SiFive estimates customers will start shipping the P650 in actual chips by 2023.
While SiFive is still several generations behind Arm, Little believes he can close the gap within its larger rival in the next several years. He said proceeds from its funding round and the OpenFive sale will help it shift into a higher gear.
He said next-generation cores on its roadmap will also open opportunities for SiFive in the personal-computer and data-center markets, where x86 processors from Intel and AMD have the upper hand.
Last year, it also rolled out the first RISC-V cores in its "Intelligence" lineup ideal for artificial-intelligence workloads. The startup said that already more than 50% of its order pipeline is for its Intelligence cores.
The NVIDIA-Arm Effect
For Little, the openness of the RISC-V architecture is what makes it stands out from rivals such as Arm and x86. RISC-V is an open standard—often compared to Linux—that allows companies to adapt CPU cores to their specific workloads without the same constraints of Arm and x86. It is also developed by a number of companies around the world, instead of leaning on the likes of Arm and Intel for future R&D.
He said companies started taking the RISC-V architecture a lot more seriously after NVIDIA announced its bid to buy Arm in 2020. The $40 billion deal would have given NVIDIA control over core designs many of its rivals rely on to design chips. The takeover raised questions from Qualcomm and other major Arm customers as well as regulators the world over whether NVIDIA would keep Arm's blueprints open to all.
Concerns over the loss of Arm's independence prompted many chip executives to take a closer look at alternates, including SiFive's CPU cores. Little said the takeover was a wake-up call for chip companies that there are risks to betting an entire product roadmap—from off-the-shelf CPU cores to the software and services that run on top of them—on a single company's proprietary, largely closed architecture.
Even though the NVIDIA-Arm deal fell apart at the start of the year due to mounting regulatory pressure, Little said SiFive's customers are not pumping the brakes on their RISC-V development plans.
“It was more of a defensive posture,” he said. “But now it has started to turn more offensive.”
Growing the Ecosystem
SiFive is also taking advantage of a broad ecosystem that is emerging around RISC-V technology.
The RISC-V ISA has been backed by many of the world’s top semiconductor firms, too, and a number of the largest contract chip makers in the chip sector are adding in support for RISC-V CPUs and other IP.
SiFive said it already has more than 300 design wins with over 100 customers, including several of the world’s largest hyperscale companies and eight of the top 10 semiconductor firms, in chips for areas ranging from automotive and augmented reality to client computing and the intelligent edge.
“The momentum begets itself," said Jack Kang, SVP of business development and corporate marketing at SiFive. "When you have customers choosing an open ecosystem, it means more software is being built, more tools are being built, and the ecosystem grows and gets stronger."
Intel, which said that it considers RISC-V as one of the world’s leading architectures with x86 and Arm, has plans to manufacture RISC-V-compatible chips at its budding foundry business. Last month, Intel pledged part of a $1 billion innovation fund to support companies in the RISC-V ecosystem, including SiFive. Intel plans to use part of funds to adapt RISC-V CPUs and other IP to its process technologies.
As the semiconductor giant behind one of the world's most widely used instruction sets—x86—Intel's investments are "historically" important for the future of SiFive and the RISC-V ecosystem, said Little.
IPO Ahead?
Even though the RISC-V architecture is lagging behind Arm—and x86 chip vendors Intel and AMD—in market share terms, SiFive and other companies have helped to validate RISC-V as a viable alternative.
"I don't think this is a market where one winner takes all," said Little.
But capturing a bigger slice of the market for high-performance processors will be an uphill battle. Arm has already put billions of dollars toward designing cores and the software stack to run on top of them.
SiFive said its new funding will help it address many of the same areas: it plans to invest in driving the growth of the broader software ecosystem and luring an even larger pool of developers to RISC-V. It is already working with Intel to develop a RISC-V SoC for software development and testing. The chip will enable a new generation of RISC-V developer boards, continuing the tradition of SiFive's HiFive boards.
Executives said the possibility of an IPO remains on the table for SiFive. Little said that he is trying to shore up the company’s business for a potential listing on the public market by early 2024.
Ultimately, Little wants to keep his options open. The plan is to prepare SiFive for an IPO by 2024, but the company could remain private longer than that if it's the wrong time.
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