The lowRISC blog

Andy Hopper joins lowRISC CIC Board as Independent Chair

Today, we are delighted to announce that Professor Andy Hopper, CBE FRS FIET FREng, has joined the lowRISC Board of Directors as Independent Chair. “I’m delighted to be joining lowRISC CIC,” said Prof. Hopper, speaking today from Cambridge UK, “As digital systems pervade every aspect of our lives trust and transparency become crucial. An open source approach allows for public inspection of the principles and implementations being used. I believe the future of digital systems will be underpinned by not for profit organisations that provide design transparency and enable real innovation.

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Andy Hopper

Introducing Greg & Tom

Greg Chadwick and Tom Roberts recently joined lowRISC’s growing engineering team. They’ve both taken some time to share a little about what they’re doing at lowRISC and what motivated them to join. Greg “It’s an exciting time to join the lowRISC team! Our Ibex core provides a solid foundation and clearly demonstrates the value of open source silicon, which I’m excited to be working on. My work so far has focused on the performance of Ibex; whilst it’s not intended as a high performance core there are various things we can do to improve it without major impact to area or power.

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Ibex on FPGA - Get stuff executed

Our microcontroller-class RISC-V processor core Ibex for sure is a solid base with which to start your own project. Over the past months, we have invested a lot of effort in making the design more mature. This includes refactoring the RTL to make the design more understandable and programmer friendly, adding UVM-based verification to the source tree, but also integrating support for the RISC-V compliance suite and enabling publicly visible, open-source powered continuous integration (CI) to keep the design stable.

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Ibex on the Nexys Video FPGA board

Ibex: Code with Confidence

Ibex, our small RISC-V core, is constantly changing. Roughly 50 percent of the RTL was refactored recently! We added features, tests, and cleaned the code up. We and our collaborators were able to make these changes (mostly) without breaking Ibex because we invested in testing: earlier this year we added UVM-based verification to the tree, and we run these tests after every change. We run static code analysis to catch common programming bugs.

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Six more weeks of Ibex development - what's new?

In the past months, we have invested considerable effort in improving our RISC-V core Ibex. This 2-stage, in-order, 32-bit microcontroller-class CPU core was contributed to us by ETH Zürich in December 2018, with activity really ramping up since May. Having been taped out multiple times (as zero-riscy) in a mix of academic and industry projects, it came to us as a relatively mature code base. Despite this, we have continued to invest in improving its design and maintainability.

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Ibex cleaning up

Large-scale RISC-V LLVM testing with Buildroot

A few years ago lowRISC started developing a new LLVM backend targeting RISC-V. Rather than copying and modifying an existing backend, in an ad hoc fashion, we started from scratch and proceeded systematically. This approach proved successful in producing a high-quality codebase. We recently announced on the llvm-dev mailing list that the backend is now reaching stability and could be promoted from its current status of experimental to an official target.

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The RISC-V LLVM backend in Clang/LLVM 9.0

On Monday I proposed promoting the upstream RISC-V LLVM backend from “experimental” to “official” for the LLVM 9.0 release. Responses so far are extremely positive, and we’re working to ensure this is a smooth process. This means that from 9.0, the RISC-V backend will be built by default for LLVM, making it usable out of the box for standard LLVM/Clang builds. As well as being more convenient for end users, this also makes it significantly easier for e.

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Introducing Sam

On June 1st, Sam Elliott followed Laura and Pirmin in becoming lowRISC’s newest employee. A few weeks into his new role, he shares why he joined lowRISC and what he’s been doing since he started. “I joined lowRISC CIC as a Compiler Developer, working on the RISC-V LLVM backend, and so far I’m enjoying working on the team! Prior to lowRISC, I worked as a compilers and programming languages researcher at the University of Washington, where I completed my Masters degree.

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lowRISC at Week of Open Source Hardware

Pretty much the whole team is in Zurich this week for the RISC-V Workshop and inaugural Week of Open Source Hardware, with a packed programme that got off to a start today and which runs all the way through to Friday afternoon. This morning lowRISC board member, Professor Luca Benini, gave a RISC-V Workshop keynote entitled, Energy efficient computing from Exascale to MicroWatts: The RISC-V playground. Our friends and close collaborators at PULP Platform are giving a number of talks this week and, we’re pleased to say, so are members of the lowRISC team!

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lowRISC enamel badge

An update on Ibex, our microcontroller-class CPU core

At the beginning of many chips projects, there’s a dream. Could we create a more future-proof chip by embedding an FPGA fabric into it? Could we measure glucose levels more accurately by integrating a small bio lab onto a chip? Could we more reliably recognize kittens in a set of pictures by implementing neural network inference in hardware? In implementation, this dream becomes a piece of hardware, with digital or analog logic, sensors, actuators, and much more.

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Ibex block diagram