Open-source effort brings SystemC to masses

SANTA CRUZ, Calif. — Launching an open-source development effort isn't a pathway to riches. But for Mark Burton, founder of the GreenSocs initiative, it may be a way to bring SystemC-based tools and methodologies into the IC design mainstream.

Burton, a former engineering manager at ARM Ltd., said he launched GreenSocs this spring on his "own dollar." The effort has since garnered considerable industry interest, he said, noting that a "birds of a feather" session on the initiative at the recent Design Automation Conference was standing-room-only.

The idea is to build a "nondifferentiating infrastructure" of SystemC models, methods and utilities, created and maintained by an active community of users, Burton said. "I would describe [GreenSocs] as the central sandbox for development of an open-source ESL [electronic system-level design] infrastructure."

GreenSocs is part of the SourceForge open-source network, which is developing SystemC library code; it operates a Web site. Current projects include a generic user bus, a configuration-at-run-time methodology, intellectual-property (IP) building blocks, an instrumentation and logging utility, and improved SystemC debugging.

"I think GreenSocs is a very good initiative, and Philips is interested in its success," said Maurizio Vitale, senior principal at Philips Semiconductors. "The key benefit for us is the development of nondifferentiating SystemC infrastructure at a cost substantially lower than what we're capable of achieving internally."

"GreenSocs seems like an attractive attempt to continue developing some open-source code of common interest to the user community," said Frank Ghenassia, director of the system platforms group at STMicroelectronics. That company has donated a SystemC parser to GreenSocs that's now available for distribution.

EDA vendors, meanwhile, don't appear to regard GreenSocs as a threat. CoWare Inc., a provider of commercial SystemC tools, serves on the organization's advisory board, noted Pete Hardee, director of solutions marketing at CoWare.

It's best that tool infrastructure and "star IP" come from commercial tool vendors, Hardee said. "Where GreenSocs can make a difference is in SystemC models for the very necessary but nondifferentiating commodity IP."

"We are happy to work with GreenSocs, which is a user-driven open-source initiative," said Adam Rose, verification technologist at Mentor Graphics Corp. "It complements OSCI [the Open SystemC Initiative] and is a useful addition to the SystemC community."

"SystemC adoption would benefit from widely available transaction-level infrastructure IP," said Robert Shutten, director of system-level solutions for Synopsys Inc.'s verification group. He added, however, that it's too early to determine what kind of business model can best provide it.

Barroom brainstorm

The concept for GreenSocs emerged at the ICCAD conference late last year, Burton said. "A number of people were sitting around in a bar saying, 'What we need is not just a language; we need to agree on how to use the language,' " he said.

Until late last year, Burton was the engineering manager for ARM's modeling group. Soon after leaving ARM (for reasons unrelated to GreenSocs), Burton said, he started thinking about the need for an open-source initiative — and decided to launch one.

"I started on my own, with help from colleagues in the industry who wanted to see this happen," he said. "It's my own dollar. I'm in an interesting position with respect to VCs [venture capitalists], because the sort of work I'm intending to do does not necessarily require huge amounts of financial input. And VCs typically get scared by the words 'open source,' even though the business model for open source is fairly sound."

Indeed, open source doesn't always mean free. GreenSocs asks for a $500 contribution for access to binary distributions for commercial use, and it offers a contracting service for companies that need help building SystemC IP. The organization, which now involves several people, also offers consulting for companies that wish to learn more about SystemC modeling.

OSCI has prepared SystemC for standardization, and the language is now before the IEEE. But the requisite "middleware" to support it — such as models and methodologies — has been lacking, Burton said, with "everybody rolling their own." As a result, SystemC wasn't living up to its promise as an easy way to exchange silicon IP.

An example of the middleware to which Burton referred is the generic bus fabric that constitutes one of the GreenSocs projects. "The way you connect pieces of IP together has a lot to do with whether you're sitting on a particular bus protocol," said Burton. "It helps if you do it the same way as your friend down the corridor, because then you have a chance of connecting your IP models together."

Another example would be a standard approach to run-time configuration. Help in that regard may be on the way from Philips, said Vitale.

"We're evaluating which parts of the Philips SystemC environment we can contribute," he said. Initially, Philips is likely to contribute a configuration system, he said.

While GreenSocs doesn't plan to provide open-source cores, the project will develop IP "that is fairly generic and that nobody cares about," Burton said. "You don't need to build an interrupt controller or a UART or a memory controller again — you've already done that a million times, and you'd be reinventing the wheel."

Why open source? "First, because that's the way you grow collaborative standards," said Burton. "Second, it enables a larger community, including [participation by] the academic community."

Complementary efforts

The first open-source SystemC tools came from OSCI, which continues to maintain an open-source language reference implementation. The exact nature of the relationship between GreenSocs and OSCI has yet to be determined, but Philips' Vitale, who is involved in both efforts, said the two groups are "absolutely complementary," assuming GreenSocs doesn't seek to become a standards organization.

"OSCI has moved from its initial strategy to develop open-source reference solutions to become more of a standards body," said ST's Ghenassia. "GreenSocs could be the next step to create an even larger user community and address some still-pending issues."

OSCI executive director Mike Meredith said the organization recognizes the importance of models and may consider further open-source development. But he said OSCI views GreenSocs as a complementary effort.

"OSCI should be the champion and guardian of the language in terms of technical content, while the language is physically owned by the IEEE," said Burton. But, "sitting behind that, there needs to be a sandbox where people can contribute ideas, play around and come up with new things."