OpenPOWER Foundation Trumpets Fully Open 64-bit Microwatt POWER Core

Microwatt by name, though not necessarily by nature, the Microwatt soft-core processor is made available under the CC-BY 4.0 licence.

OpenPOWER Foundation executive director Hugh Blemings has officially launched the Microwatt soft-core processor, a 64-bit POWER design written in the VHDL hardware description language and released under a permissive licence — a first for the organisation and the POWER instruction set architecture.

Following the growing success of free and open source silicon efforts, in particular RISC-V, OpenPOWER made the move to release the POWER architecture — originally created by the Apple, IBM, and Motorola triumvirate known as AIM — under a permissive licence, finally living up to the "open" part of OpenPOWER. "By moving the POWER ISA under an open model - guided by the OpenPOWER Foundation within the Linux Foundation - and making it available to the growing open technical commons," Foundation executive director Hugh Blemings claimed at the time, "we’ll enable innovation in the open hardware and software space to grow at an accelerated pace."

The first open implementation of the POWER ISA followed: Microwatt, designed by a team at IBM led by Anton Blanchard. While Microwatt was quietly launched onto the project's GitHub repository with surprisingly little fanfare, Blemings has now opted to begin trumpeting its availability from the rooftops - including the promise of more to follow at the OpenPOWER Summit Europe event at the end of the month.

"While originally intended as a proof of concept, the core has garnered global interest from the open community — with intrepid early adopters contributing code to extend and improve it," says Blemings of the Microwatt core. "So why the excitement? On the lowest level of the stack, Microwatt gives interested parties a way to play with custom instructions and changes to the CPU itself. As one open source developer put it to me 'It’s just a make away.'

"Microwatt also gives developers the opportunity to try out a basic 64-bit POWER core on low cost FPGA hardware or even in a software simulation environment. Taken together these in turn open up the possibility of embedded and purpose-built accelerator applications based on POWER – developed with something like Microwatt, implemented on a high end FPGA, ASIC or custom silicon. That’s pretty cool."

Microwatt was presented at the OpenPOWER Summit NA earlier this year. (📷: OpenPOWER Foundation)

The OpenPOWER Foundation has a long road ahead of it, however: RISC-V has both a head-start and a number of high-profile adopters, including Western Digital, Synaptics, and Nvidia. The POWER ISA, by contrast, has largely fallen out of favour for mainstream use though still enjoys some popularity in the high-performance computing, high-security system, and field-programmable gate array sectors - and, famously, drives the NASA Mars rover Curiosity.

Those interested in getting started with Microwatt can find the VHDL source on Blanchard's GitHub repository.

Gareth Halfacree
Freelance journalist, technical author, hacker, tinkerer, erstwhile sysadmin. For hire: freelance@halfacree.co.uk.
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