Semiconductor Design Consolidation: MIPS -> RISC-V

Consolidation in the semiconductor industry continues. The latest event is MIPS Technologies embracing the open source instruction-set architecture (ISA), RISC-V, and no longer designing for the MIPS architecture that gave birth to the company more than three decades ago.

While this news, reported in the trade publication EE Journal, does not have the eye-popping dollar amount of Nvidia acquiring Arm ($40 billion) or AMD acquiring Xilinx ($35 billion), it’s no less significant. It’s evidence that RISC-V is flexing its open source muscle and making progress in becoming the open standard for a foundational task of technological innovation -- chip design. With the once-prominent and engineer-beloved MIPS’s participation, the RISC-V ecosystem may soon mature to be a legitimate alternative to Arm, which will have massive technological, business, and geopolitical implications.

MIPS, RISC-V Similarities

From a technological standpoint, this “marriage” between MIPS and RISC-V is quite natural. As I described in “When ‘Jurassic Park’ Goes to China” last year, the MIPS architecture was first developed by Stanford professor (later president) John Hennessey and his computer science students back in 1981. MIPS was one of the first RISC-family of chip architectures that gained wide usage, and influenced the designs of other RISC-based ISAs that came after it, including RISC-V. (MIPS’s creation predated RISC-V for about two decades.)

Quick aside on definitions: The “R” in RISC stands for “reduced”, while the “C” in CISC stands for “complex”. This reduced architecture enables and optimizes simple computation instructions well. Think elementary school math: addition, subtraction, multiplication, division, etc. It’s less capable of supporting complex mathematical operations, like matrix multiplication and partial derivatives (used widely in Deep Learning AI). The most popular RISC architecture in the market is Arm. The CISC counterpart is Intel’s x86.

RISC-V’s creator, Dave Patterson of UC Berkeley, also co-authored two seminal books with Hennessey on computer architecture that are widely used as textbooks. So whether it’s the technology or the people behind the technology, the stories of MIPS and RISC-V have been deeply interconnected from the beginning.

That interconnectedness extends to today. In response to MIPS Technologies’ decision to design for RISC-V (and not MIPS), the CTO of RISC-V International (the nonprofit that governs the RISC-V project and ecosystem), Mark Himelstein, told EE Journal the following:

“I would personally say that the simplicity and elegance of RISC-V most reminds me of MIPS more than any other architecture. I am excited about the company’s next steps, including their involvement with the community and to see what RISC-V products they will bring to market.”

Himelstein himself worked as an architect at MIPS Technologies from 1985-1991, during the company’s heyday as a young, prominent rising star. (MIPS IPO’d in 1989.)

Consolidating (Some) Developer Mindshare

MIPS and Arm used to be rivals in the 90s. At that time, the market’s general impression of the two options was that cellphone makers tended to like ARM, while engineers and developers preferred MIPS.

Since MIPS’s first IPO, acquisition by Silicon Graphics, and a second spin-off IPO, the company’s business traction waned, while Arm flourished and dominated the market. MIPS did open source its ISA (similar to RISC-V) as a tactic to stay relevant in 2018 via the MIPS Open Initiative, but the program shut down less than two years after launch. Here’s a good timeline put together by Reuters that tracks how MIPS’s IP got licensed to China and its troubled corporate history, which ended in an acquisition by Wave Computing that is now bankrupt:

Meanwhile, some of MIPS’s developer goodwill and mindshare persisted, partly due to its place in the core curriculums of many university computer science programs, where new technical talent is being trained. Even though MIPS Technologies is a shadow of its former self, its embrace of RISC-V could bring over and consolidate some developer mindshare, which would be valuable for RISC-V’s own ecosystem growth.

As I mentioned in a previous RISC-V deep dive post, RISC-V is facing a classic problem of not having a big enough software ecosystem to take it to the next level. It’s classic because RISC-V isn’t the first open source ISA. Its predecessors, OpenRISC and OpenSPARC, have all lost relevance due to a lack of software ecosystem to fuel their growth. And the key to building a sustainable software ecosystem, even (or especially) for a hardware project, is to own more software developer mindshare.

The thing is an ISA by itself isn’t that valuable. Borrowing an analogy from an entrepreneur in the RISC-V space: an open source ISA is more like the English grammar -- not that valuable until enough people use it to write the great novels, academic papers, legal contracts, etc.

Similarly, the production silicons (actual chips that can be deployed in devices, the “novels”, if you will) are what make RISC-V valuable, not open source per se. Sadly, RISC-V isn’t at that level yet, because not enough developers “speak” RISC-V. Thus, it’s not surprising that there is no volume production of RISC-V-based chips, despite the enthusiasm surrounding the technology.

MIPS Technologies’ commitment to RISC-V might just give its software developer ecosystem a boost -- not a big one, but a relevant one. That relevance comes from MIPS’s original design decision to move the software layer towards the hardware layer, as opposed to the reverse direction, which was the mainstream design philosophy at that time. This choice was made in part because the Hennessey-led research team that created MIPS had renowned technical strength in building compilers -- the layer of software that translates the source code that human beings write (e.g. a for loop) into machine code -- something a chip can understand and process.

Attracting more compiler engineers to build on top of RISC-V is critical to its success. That’s why the MIPS news is important, despite little media fanfare and no attention-grabbing dollar amount.

Power to Standardize

Stepping back to a macro level, one of the most powerful elements of open source is its ability to become a standard which other technologies will build on. It’s the holy grail that every ambitious open source project wants to reach. And despite some of my bearish sentiments around RISC-V, it’s now poised to become a standard (slowly but surely) with the help of MIPS, and I hope it succeeds.

In the future, every layer of a technical stack will have one or two open source winners and one or two proprietary solutions, with the open source ones eventually becoming the standard. This long-term momentum behind open source is somewhat inevitable, because developers prefer it for its easy access and transparency, while the companies who employ developers prefer its vendor neutrality, robustness, and the self-fulfilling rationale that the developers whom they want to hire prefer open source (for more of my thoughts on developers, please see Part I of my Global by Nature series).

This dynamic has already played out in several layers:

• General purpose operating system: Linux (open source), Windows (proprietary)
• Mobile operating system: Android (open source), iOS (proprietary)
• Cloud container management: Kubernetes, OpenStack (both open source)
• Front-end framework: React, Vue, Angular (all open source)
• Backend web framework: Node.js (open source)
• AI/ML framework: Tensorflow, PyTorch, Keras (all open source)

Other layers, like databases and big data analytics, are crowded with many solutions vying to become the standard. New, emerging layers like 5G are currently dominated by proprietary solutions (Huawei, Ericsson, and Nokia), while open source projects like OpenRAN, Open Network Automation Platform, and OpenAirInterface are promising but still immature.

As for the all-important semiconductor industry, it does look like RISC-V will become an open standard that will chip away at Arm/Nvidia and perhaps x86 too. It's a standard that any person, company, and, yes, country can use however it seems fit. The question is when, not if.

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