Open-source chip RISC-V to take on closed x86, ARM CPUs

There are a number of things that make RISC-V different from OpenSPARC. One is that OpenSPARC is not a very scalable design, it could probably only ever work in servers and workstations, and workstations are essentially a monoculture. Another reason is timing: manufacturing processes have effectively stopped yielding performance and power gains as the fundamental constraint (distance between components on chip) doesn't get any smaller. This means that in order to keep the pace up for any popular workload, many new microarchitectures will need to be created. RISC-V is amenable to a wide array of microarchitectural decisions, and doesn't carry the architectural baggage of ARM and MIPS licensing and technical quirks, or the impossible licensing of x86.

> But does anyone expect RISC-V to really go head-to-head with Xeon, Opteron, ThunderX, Centriq?

Except for Intel, none of these manufacturers have any reason to resist RISC-V. All of these vendors can directly port knowledge from one ISA to another. So really it becomes a matter of "will there be a demand for RISC-V hardware in the server and workstation markets?", and the answer to that is a firm "maybe".

I think that today, since most software is written in high level languages which are at least as abstract as C, there is little reason why a new ISA couldn't take hold in any of these markets if hardware vendors can promise good things to ISVs and to customers who write their own software.

At present, there is a considerable barrier to entry for new designers and manufacturers to approach ARM, POWER, and MIPS, and basically no hope of manufacturing an AMD64. ARM is not the cuddly RISC architecture people think it is, it is in many ways nearly as quirky as x86, and therefore very expensive to enter and innovate on. Furthermore, it can take more than a year to negotiate an architectural license with ARM, your company or the market might no longer exist by the time you close the deal. POWER is not too far off on licensing, and it's not all that elegant either (though far more surmountable than ARM). MIPS lacks industry momentum and standardized high performance feature sets (wide vector compute, hardware security features), and its custodian company seems to barely acknowledge it exists.

All in all, nobody knows if it'll work out, but there are good reasons for RISC-V to succeed in the market. The challenges also seem surmountable.

ARM is too license-encumbered. If we're going to switch away from x86, it might as well be to something that admits free development and production.

I am curious as a total novice why chips and why now? As you said ARM is cheap. For price to performance I don't see why there aren't multi-motherboards coming out.

Someone made a 10 raspberry pi MoBo which if it is cost effective would be easier than a cluster. I think it would be awesome if that was scaleable but I am sure there is a reason. It would be cool and save space making a cluster out of 4 of those boards rather than 40 rPis

The RISC-V team was very careful in establishing prior art for every design decision. The patents on ISAs tend to be on their quirks, so keeping things truly minimal helps avoid all of that complexity.

Like a lot of what Sun did, prior open chip designs weren't good enough. Academics starting with a clean slate and a 20+ years of additional experience gives RISC-V real advantages over MIPS and ARM.

The primary advantage is that RISC-V is truly RISC: they have a core ISA that is frozen but extendable. This means that they can have application-specific CPUs with intelligent fallback and full compatibility.

As to why now, well, they came up with RISC-V as a teaching ISA and started getting emails from industry asking why it had changed from last semester. It turns out that chip manufacturing has gotten cheap, with custom runs on 28nm processes going for $30K.

You are correct in that their early target market are co-processors and other niche components. Just getting a license from ARM is 10+ million dollars. But the biggest cost in building your own ISA is investment in software and tooling. RISC-V gives a common foundation for everyone to build on.

However, their intent is indeed to bring competition at every level. Their licensing scheme was chosen specifically to allow big players to create IP and keep the secret sauce to themselves, unlike SPARC V8 and OpenRISC.

Apple creates their own CPU and GPU designs, Google has custom hardware for machine learning, and Samsung is about to overtake Intel as the world's largest chip manufacturer. Why should they keep shelling out billions to ARM, Intel, and AMD just to use their ISA?