What Does the Open Sourcing of MIPS Mean for RISC-V

已有 1111 次阅读 2019-5-28 23:49 |个人分类:技术类|系统分类:科研笔记

Looking back over the year, there is no doubt that the rise of RISC-V will be seen as one of the major computing trends of the year.

“…generally speaking RISC-V seems to be killing off any of the minor licensable instruction set projects, just like ARM has mostly killed off the custom vendor-specific instruction sets already.” — Arnd Bergmann, Linux Kernel Developer

However things got rather interesting when, in what came as a surprise to almost everybody, Wave Computing announced that they were open sourcing the intellectual property behind the MIPS processor.

Wave Computing, a machine learning startup, only acquired the intellectual property rights for the MIPS processor this past June from Imagination Technologies, who in turn purchased the technology back in 2013 in a move that was—at least at the time—seen as one taking the MIPS architecture off the board. Reducing the players down to just Arm and Intel.

The acquisition of the MIPS intellectual property seems to be part of Wave Computing’s pivot away from the data center, and towards edge computing. Which, of course, is another of the bigger trends we’ve seen during the year. It was also a role reversal of the typical trend we’ve seen over the last few years, with processor manufacturers like Intel buying up machine learning startups.

Like RISC-V, MIPS is a RISC architecture, but one with a long history. Initially developed by Silicon Graphics (SGI) as a workstation and server architecture, the intellectual property was later spun off into its own company which had some success becoming the default architecture used by set-top boxes and routers. But over time Arm, which historically has dominated the mobile sector, has marginalising the MIPS architecture. Apart from the rather lacklustre attempts by the Chinese government to kick start development of a MIPS clone architecture, it hasn’t gained any real traction in the space.

Which raises questions why Wave Computing wanted the MIPS intellectual property in the first place. With most of the major software for machine learning focusing around the Arm architecture, MIPS seems a curious choice.

However given Wave’s acquisition of the MIPS, and with a background of the rapid growth of RISC-V over the last one to two years, open sourcing the MIPS intellectual property seems like an obvious—if surprising—move in hindsight. While RISC-V is gaining grown the storied history of MIPS means that the MIPS stack is far more complete, and includes things like DSP and SIMD extensions that still don’t exist for the RISC-V platform.

“Under the MIPS Open program, participants will have full access to the most recent versions of the 32-bit and 64-bit MIPS ISA free of charge — with no licensing or royalty fees. Additionally, participants in the MIPS Open program will be licensed under MIPS’ hundreds of existing worldwide patents.”

Yet it’s still somewhat unclear how open sourcing MIPS will work, as the company somewhat confusingly talks about “new MIPS Open licensees” and the need to “register” in its discussion of their new MIPS Open initiative. Such talk will make some, initially excited by the idea of an open MIPS processor, somewhat wary of how heavy weight the paperwork involved in getting access to the architecture might eventually prove to be.

“The MIPS-based solutions developed under MIPS Open will complement our existing and future MIPS IP cores that Wave will continue to create and license globally as part of our overall portfolio of systems, solutions and IP.”—Lee Flanagin, Senior VP and CBO Wave Computing

However they have said that “once the MIPS Open Community is launched,”registered members will have access to an open source “version” of the 32- and 64-bit MIPS Instruction Set Architecture (ISA), Release 6, along with the MIPS SIMD and DSP Extensions, MIPS Multi-Threading (MT), the MIPS MCU, the microMIPS architecture, and MIPS Virtualisation (VZ). Which seems to be pretty much everything you need to build a real MIPS core.

It’s going to be interesting to see how the “open silicon” community reacts to the announcement. Because, despite yesterday’s announcement, the historic issues around MIPS aren’t going to go away overnight.

With the growing support we’ve seen around the RISC-V platform over the last year, you have to wonder whether open sourcing MIPS is too little, too late, to save the architecture from becoming irrelevant.

Details on the MIPS Open initiative can be found on the Wave Computing site, and eventually will reside on the MIPS Open Community site. According to the company we can expect “more details” including “downloadable MIPS architecture, licensing, and other information on how to participate,” at the start of next year. Once we have those, it’ll be more readily apparent whether open sourcing the MIPS architecture makes it once again a contender, or whether this is purely a desperation move by Wave.





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