Arm is pushing out x86, RISC-V is pushing out Arm
Part 1: Arm vs x86 (Intel and AMD)
The Next Platform had an interesting article heralding that the current market leader x86, the CPU ISA [1] used by Intel and AMD, will be unseated by Arm, the CPU ISA licensed by Arm Ltd to anyone. Current trends seem to indicate this, with Arm having a near monopoly in smartphones, making big inroads into PCs with Apple and Qualcomm’s chips, and expanding rapidly in servers with Amazon AWS’s Graviton series, Ampere Computing’s processors, and Nvidia’s upcoming Grace processor. x86 keeps losing market share to Arm every year, and it’s showing no signs of slowing.
The history of computing is full of paradigm shifts that shake up who the major players are: in the enterprise/server market, the status quo shifted from the mainframe to the minicomputer, to RISC/Unix microprocessor systems, to Intel/x86 systems. IBM, DEC and Sun Microsystems all had their turn in the limelight, then declined. And the attack always comes from below, from cheaper systems scaling up in performance: minicomputers were much cheaper than mainframes, RISC/Unix microprocessor workstations were cheaper than minicomputers, then scaled up to server systems, and finally IBM PC compatibles using x86 were even cheaper still, and scaled up to the servers we have today.
In this timeline, Arm Ltd was a player in the RISC/Unix microprocessor era (initially as Acorn Computers, then Advanced RISC Machines), was squeezed out of most markets by Intel/x86 along with most other RISC players at the time, and survived by specializing in low power applications such as microcontrollers and embedded systems. This positioned them to capitalize on the smartphone boom: in 2007 the first iPhone, first BlackBerry Curve, and in 2008 the first Android phone (HTC Dream), all used Arm CPUs. Arm’s success in smartphones helped them expand into other markets, such as tablets, laptops and servers, continuing the pattern of attacking from below and scaling up.
The secret to Arm’s success is in its openness: any company can license Arm Ltd’s complete CPU core designs and use them in their product, or can license the Arm ISA itself and make their own core design, like Apple does. Companies like to be differentiated from their competitors, and large companies like to have custom hardware designed for their specific needs: Apple, Samsung, Nvidia, Amazon AWS, Huawei, etc. all make their own Arm processors for use in their own products. There are also companies that make Arm processors for a specific market niche and sell them on the mass market, such as Qualcomm, MediaTek, Ampere, Marvell, Broadcomm, etc. This has lead to a thriving Arm ecosystem of many hardware manufacturers and companies making software for Arm CPUs, and it is this ecosystem that is a threat to the x86 ecosystem of Intel and AMD. The x86 ecosystem has decades of software written for it, so many companies are locked into x86 via their software, but newer applications like machine learning aren’t so limited, and system makers like Apple, Amazon AWS and Nvidia have enough control over their software that they can move their entire ecosystem over to their own Arm processors. And so Arm gains more market share over x86 every year.
Part 2: Companies can pivot to survive
However, even if x86 does decline into a market niche of running old software, like mainframes did before them, this doesn’t mean that Intel and AMD’s CPU divisions must suffer the same fate: Fujitsu transitioned their line of SPARC ISA server processors to Arm, starting with their A64FX processor. And AMD flirted with abandoning x86 and jumping ship to Arm in 2012–2014, under CEO Rory Read’s pivot to stop competing with Intel; this was scrapped by the next CEO Lisa Su. One product was released, the Opteron A1100 series, and a custom Arm CPU architecture called K12 was in development, perhaps even finished, but no products were released. This means it is more than possible that AMD will jump ship to Arm if it looks like x86 is sinking. And IBM, the megalith of the mainframe age, is still making POWER ISA based servers and has a huge services portfolio. If a company can adapt to the paradigm shifts in the market, it can survive and even succeed in the next age. So we may be seeing Arm CPUs made by Intel sooner than we think.
Another possibility is Intel and AMD opening up and licensing x86 cores / ISA the way Arm does: last year Intel announced that they will license their x86 cores for use in other processors, as long they are fabricated at Intel’s foundry. And AMD currently makes semi-custom chips for game consoles that are co-designed with Sony and Microsoft, and there was an AMD-Chinese joint venture that produced a processor using x86 cores, but this was halted during the U.S.-China trade war in 2019. If Intel and AMD become more aggressive with licensing and working with other companies on hardware, they could woo some companies to make their custom processors with x86 cores rather than Arm cores.
Part 3: RISC-V vs Arm, even more open
RISC-V is the new CPU ISA upstart and it has been gaining market share in Arm’s former stronghold in small embedded cores. RISC-V is an open source CPU ISA created at the University of California, Berkeley, and currently managed by RISC-V International, a non-profit steered by its members, such as Google, Samsung, Intel, AMD, Nvidia, Qualcomm, etc. Being open source, it can be used by anyone without paying royalties, and designs using it can be customized to an even greater degree than with Arm. It has started to gain traction as small embedded cores, a niche previously ruled by Arm: Western Digital changed their SSD controllers from using Arm CPUs to their own RISC-V CPUs, Nvidia and Qualcomm use RISC-V CPUs in their control systems in their larger processors, and Google is planning to use RISC-V CPUs in their next generation TPU machine learning processor. There’s even two companies with plans to make large 8-wide RISC-V CPUs for servers, Tenstorrent and Ventana, scaling up RISC-V to the top tiers of CPU performance.
However if RISC-V is to challenge Arm and x86 in the mass market they have a long way to go, Arm and x86 each have a software and hardware ecosystem that they grew over decades, and it could take over a decade for RISC-V’s ecosystem to grow enough to challenge them. Still, at this point underestimating the cute little open source CPU would be a costly mistake.
Footnotes:
[1]: An instruction set architecture (ISA) is like the language a CPU speaks. Software targeting an ISA will run on all other CPUs that use that ISA.
