Is RISC-V going to kill ARM?

This article talks about the emergence of RISC-V processor ISA, reasons for its rising popularity and the benefits it brings. It also talks about challenges, status of implementation and prospects for adaptations in various application domains. Anyone having interest in computing and related field could be the audience of this article.

Introduction 

Ever wondered there is an ARM core in almost every embedded SOC that you see, irrespective of vendors (like Qualcomm, Broadcom, Nordic etc.) or technology (connectivity, or MCU or graphics etc.)?  

Isn't it too much dependence on one company? What if due to some business reasons ARM decides to not sell it to other companies? Isn’t it too much dependence on one company for the development of new processors? What if ARM decides to drastically hike its design IP’s licensing fee? 

If any of the above happens, the entire industry will struggle. If you replace ‘ARM’ with ‘Intel and AMD’ and ‘embedded SOC’ with ‘high end processors’, most of the above concerns hold true as Intel/AMD rule the high processing power (x86 based) processors. Companies are trying to find solutions to most of the above concerns in RISC-V. RISC-V is an open-source ISA (instruction set architecture) based on the principles of RISC (reduced instruction set architecture).  

Processor cores are at the heart of each SOC. ARM cores are the most popular processor core IPs in embedded SOCs due to their sheer performance coupled with energy savings, security and other features. Same is the case with x86 ISA architecture adopted by Intel/AMD in high end computing space. 

This write-up talks about RISC-V's benefits, challenges, the current state of implementation and the opportunities going ahead. Idea is not to detail out the internal details of RISC-V ISA architecture or compare it with existing ISAs in great technical detail but to give a holistic view of what is happening in the processor design space and why RISC-V is getting so much traction from the range of semiconductor vendors be it large or small, governments and startup accelerators alike. 

What is RISC-V? 

RISC-V is an open-source ISA (instruction set architecture) based on the principles of RISC (reduced instruction set architecture). It combines a modular technical approach for open, royalty free ISA, which means that anyone, anywhere can take the IP contributed by the community members and build their custom hardware. 

RISC-V standard defines a small set of instructions and built to allow extensions which is suitable for all kinds of applications including low processing power processors, low power and high-performance processors. Consider this as an open standard that promotes community development of processor designs, software tools and operating systems and hence allows rapid and cost-effective development of new processors and SOCs.  

Being open source, it enables various processor vendors to access the standard ISA specification freely and extend it as per their custom requirements for various end applications. It follows permissive licensing I.e. custom design makers are allowed to make their own custom design from the open-sourced specification and keep their modifications private without the need to share it back to the community. This kind of licensing is a great attraction for chipmakers that put lot of resources and effort into building custom designs as they can controllably monetize it without sharing the designs with others. More precisely, it uses ‘creative commons (CC) license’. A similar type of permissive licensing is Apache 2.0 which is quite popular in software and used by Android, Kubernetes and Apache Hadoop, OpenCV etc. 

Now, the question is why is it getting so much attention from major semiconductor industry leaders? 

Reasons of Popularity 

Monopoly of ARM & Duopoly of Intel/AMD 

The current processor market is dominated by ARM and x86. ARM rules the embedded space while x86 (Intel/AMD having highest market share) is in high end processor segment. This monopoly or duopoly of vendors is a risk that no semiconductor chip makers (more specifically customers of ARM or Intel/AMD) want to continue with. 

Recently it was also heard that ARM is increasing the license fees and shifting from per chip-based license to per end device manufactured based license fee in order to increase profitability which will further add cost.  

ARM has also decided to disallow mixing of other ISA architectures along with ARM ISA on the same package. That means #tbd 

ARM’s holding company I.e. ARM Holdings Plc. is also vulnerable from acquisition perspective. It was acquired by Softbank a few years back and recently there was an attempt by Nvidia to acquire ARM. Consider the situation that one of the SOC makers buys it and stops selling the IP cores to other competitors such as Intel or Qualcomm etc. To overcome this situation and reduce dependency on ARM, these companies have come together to build an open ISA architecture which is based on RISC principles and specifically called RISC-V. 

Open and simple base ISA, built for extensions 

RISC-V defines base ISA standards and will work towards building its extensions. Anyone can take these IPs and build their custom hardware. This licensing is such that they can share back to the community or keep their design private. This flexibility is a great attraction. 

This also enables new startups easy entry to SOC design space. The startups can design new SOCs by accessing the open standard for processor designs and take advantage of tools and other ecosystem software developed by the open community for free. 

Community based development 

2 main consortiums have been built i.e., ‘RISE’ (RISC-V Software Ecosystem) and ‘RISC-V international’ to support community-based development. RISC-V international is focused on building ISA standard from the hardware perspective, while RISE platform is meant to promote community-based development of software tools and operating systems. 

The RISE community (link) is built by hundreds of industry leading companies to support commercial software development for RISC-V architectures. It is hosted by the Linux foundation Europe and as per the latest information available on their website the current focus areas of RISE members are as listed in the table below;  

RISC-V International (link) is the main governing body for RISC-V standards development and promotes overall hardware and software development towards RISC-V architecture. It comprises 3950 members as per latest records including the likes of Qualcomm, Google, Samsung etc. 

Emergence of new processing requirements 

The processor development has been stagnating due to limited differentiation made by processor designs (in computing) for several years. There has been a great focus on software-based improvements. However, latest trends like AI, ML, AR, VR and various other applications require specific designs of HW accelerators and improvements over existing processor designs. Even for the established players like ARM, these are new requirements and designs have to be evolved to meet these requirements. This phenomenon places all ISA architectures (RISC-V and likes of ARM, x86) on a level playing field. Being open source with permissive licensing, chip designer companies can also safeguard their monetary interests. 

The benefits 

Following are a few important benefits that RISC-V based initiatives are bringing to semiconductor manufacturers - 

• Single base ISA architecture for low end application power efficient computing to high processing computing. Amazon is already running ARM (RISC based) based chipsets in server applications commercially with success. This gives confidence in its use in sever applications as RISC is the foundation architecture for RSIC-V too. 

• Faster development time for major software components due to community-based development. 

• Large developer community due to community and standardization of tools. Therefore, hiring developer resources becomes easier. 

• Proven record of other open-source projects’ success such as Linux etc. 

• Cost effective as it is licensing free, permissive form of open-source licensing meaning there is no compulsion to contribute back to community.  

• Allows entry of new startups and players in the processor and SOC design space, and hence expedites the overall ecosystem development. 

• Open standard based hardware and software development will ensure reuse of tools, software, operating systems. 

The challenges 

Significant resources and efforts are required at this stage to bring it to the level of more established competitors like ARM ISA or Intel’s x86. One example is that Intel dropped its project pathfinder meant to provide pre-silicon simulations for RISC-V based designs, in the middle. That could be due to resource investment. The ecosystem of software tools, development environment, operating systems, SOC and processor design verification tools is also evolving.  

From the EDA (Electronic Design and Automation) tools perspective, RISC-V presents special challenges because its specification is designed to provide a configurable and customizable solution for general-purpose processors. There are many options and variations defined in the ISA specification, and users are permitted to extend the ISA even further by adding custom instructions. Therefore, any RISC-V verification solution must be flexible enough to accommodate customizations. 

Similarly, as the RISC-V architecture is being adopted for high-end applications like HPC and mobile, the PPA (power, performance and area) requirements are also demanding, which requires industry-leading design automation tools and methodologies. 

Since RISC-V allows a high degree of customization, there is a risk of fragmentation and inconsistency among different RISC-V-based processors and platforms. This may affect the interoperability and portability of RISC-V software and hardware, as well as the testing and verification of RISC-V components. 

Loyal and conservative customers of established ISAs may be difficult to convince to move away from existing ISAs. It's difficult to gain confidence of existing customers of these proven ISAs. RISC-V will have to differentiate offerings and provide a differentiated value preposition. 

RISC-V is also becoming the new battleground for China-US tech war. Both Republicans and Democrats in the US have asked the US government to put regulations and export control (licenses) on the RISC-V collaborations by American companies with China as they fear that US may lose lead in the chip design space with such open access to deep technology and will be difficult for US to put sanctions on China. In fact, China may use the technology in building building military hardware. That said, let us see what turn it takes as major US and European semiconductor vendors are also the ones promoting it the most. (link) 

Current State & Prospects

RISC-V is gaining momentum but remember that it is a new initiative. SOC makers are setting up teams and investing in startups to onboard this new arena of development. IOT and wireless chipset makers like Nordic, Espressif or TELink etc. are already making RISC-V based SOCs.  

Nordic has recently launched nrf54 SOCs that use RISC-V based coprocessors along with ARM. (link)

Qualcomm has partnered with Google to build RISC-V based wearables platform. (link)

Intel also joined the RISC-V International last year as a premier member of the organization that shows it is also convinced about the potential of this phenomenon and willing to along with their existing focus on x86 architecture. 

SiFive is a startup focused on developing commercial processor cores around RISC-V. Announces Differentiated Solutions for Generative AI and ML Applications Leading RISC-V into a New Era of High-Performance Innovation. (link)

Synopsys is working to meet demand for processor design and verification tools for RISC-V. (link)

India launches Digital India RISC-V (DIR-V) program for next generation Microprocessors to achieve commercial silicon & Design wins by December'2023. (link) 

In feb 2023, Ventana targets hyperscalers with customizable RISC-V datacenter chip - (link)

Several new technologies such as IOT, 5G, AI, AR, VR are emerging, and a lot of processor design improvements are required even in the existing ARM cores. Therefore, it is evenly poised now against ARM as processor-based accelerators demand is increasing and a lot of evolution in processor space is happening.

Trend with respect to computing power

The above projection may seem a bit too optimistic in terms of the growth of RISC-V for high end applications. As of today, I.e. in 2023, we do not find much traction in the mobile computing or high end processing applications and major players like Qualcomm, Samsung and others are still producing ARM based SOCs. Very few have adeopted RISC-V in high end processing segment but It looks like once the RISE community enables support on some of the critical tools like Qemu etc., the growth of RISC-V will increase exponentially.  

Industry wise trend and projection 

Here is a projection with respect to industry categorization by Semico research;

Major adaptation is happening in IOT and industrial domain already. However, it is expected to rise in a big way in other domains in the next 3 years. 

Semiconductor industry players Robert Bosch GmbH, Infineon Technologies AG, Nordic Semiconductor, NXP® Semiconductors, and Qualcomm Technologies, Inc., have come together to jointly invest in a company aimed at advancing the adoption of RISC-V globally by enabling next-generation hardware development (link). The initial focus of this company is automotive followed by other domains. 

Conclusion 

RISC-V is relatively a new phenomenon with great promise. A similar success story of Linux in operating system space and the interest shown by major SOC and processor makers bolster this belief.  

It is already being adapted in IOT, new use cases such as AI, AR, VR etc. and even in high end processors in the servers' domains. The RISE community based openly and freely available software development and the motivation in the SOC makers community to move towards an open standard based architecture, are the main driving forces behind its projected success.  

It may not replace ARM in the smart phone and tablet space completely soon due to the natural evolution cycle of technology and conflicting performance (power vs processing) requirements in this arena. It took years for ARM to build the technology and brand in the smart phone devices space, which is difficult to replace. Same is true for x86 in high end processing space but looking at the current traction and excitement shown by existing semiconductor players, RISC-V certainly has bright prospects and it is a race to watch out for.

References 

• https://www.nordicsemi.com/Nordic-news/2023/08/leading-semiconductor-industry-players-join-forces-to-accelerate-risc-v 

• https://semiengineering.com/is-risc-v-the-future/#:~:text=With RISC-V covering a,V CPU cores by 2025 

• https://riscv.org/ 

• https://telecom.economictimes.indiatimes.com/news/devices/qualcomm-google-partner-to-make-risc-v-based-wearables/104512034#:~:text=“Qualcomm Technologies, Inc.,said in a statement Tuesday.