OpenAccess adoption challenging, worth it

Adopting the OpenAccess database brings chip designers tremendous benefits, but it's a challenging task that should not be taken lightly, according to representatives of three large companies that have made the plunge.

Speakers from Freescale, LSI Logic and IBM, taking part in a panel discussion at the recent OpenAccess Developer's Forum, each showed how their companies are adopting OpenAccess and migrating internal tools to run on that database. All three are active in the silicon integration Initiative's (Si2's) OpenAccess Coalition, a group of large user companies and EDA vendors working to forge a standard design infrastructure based on OpenAccess.

The presenters said that OpenAccess provides an integrated design system that consumes less memory and offers better performance than existing proprietary data models. But they also said that migrating internal tools, and getting "buy-in" from design groups within their companies, took time and resources.

The OpenAccess Coalition has been around for three years, and many of its key backers are in the early stages of adapting their design systems to run on OpenAccess. Steve Schulz, president of Si2, said OpenAccess adoption is running about six months behind what he previously expected, but that "the pipeline is full" of companies starting projects.

Just prior to the OpenAccess Developer's Forum, Si2 announced OpenAccess ver 2.2, which brings both logical design and manufacturing data into OpenAccess and promises compatibility with all future releases—something that the 2.1 release lacked.

Uniting warring tribes

Mark Johnstone, distinguished member of technical staff at Freescale Semiconductor Inc., noted that design groups at Motorola Inc. were "traditionally a culture of warring tribes." When Motorola spun off Freescale, he said, it was important to forge a more unified design flow, allowing for the exchange of IP. OpenAccess provided a means to do that.

Johnstone added that Freescale looked at 15 other data models before it settled on OpenAccess. "It was the only one that fulfilled all our needs," he said. Among the attractions: free translators, the ease of moving from Cadence's old CDBA database to OpenAccess and the opportunity to influence OpenAccess development by serving on the coalition's change team.

Freescale is migrating internal tools to OpenAccess using what Johnstone called a "thin layer" built on the OpenAccess data model. To minimize design flow disruption, they're converting small, consistent sets of tools at one time. For Cadence tools, the translation from CDBA to OpenAccess is "relatively painless," Johnstone shared.

Johnstone said that OpenAccess uses less compute time and memory than the previous internal data model and is more expressive. Cadence's OpenAccess tools, he said, are "blindingly faster" than their CDBA counterparts. One problem, however, is that some of Freescale's EDA partners do not support the OpenAccess database. In a pointed reference to Synopsys Inc., Johnstone spoke of "a certain large EDA vendor whose name begins with S."

But the migration went more slowly than expected, Johnstone said. "It's a large task," he said. "Don't underestimate what you're getting into."

Responding to a question from the audience, Johnstone said Freescale is now about "10 percent converted" to OpenAccess.

Another adoption story came from Scott Peterson, director of RapidChip Technology at LSI Logic Corp., who also chairs the OpenAccess Coalition. He noted that LSI Logic uses both internal and external tools, including Synopsys tools that run on the Milkyway database.

LSI Logic first tried a layout application on the OpenAccess 2.0 database, Peterson said, and found a threefold reduction in file size compared with GDSII. Then, he said, the company decided to "dive with both feet" into OpenAccess and use it to build RapidWorx, a new design system for LSI Logic's RapidChip structured ASICs.

This process is now partially complete, with some internal RapidWorx tools running on OpenAccess.

But what about those Synopsys tools used for physical design? LSI Logic built a Python interface on top of Milkyway and OpenAccess and plans to use that to transfer data between the two.

"OpenAccess was a positive experience for LSI, but it's not without cost," Peterson said. "We invested time and resources into this project." On the plus side, he noted, LSI Logic was able to drop its internal database.

IBM Corp. isn't as far along as Freescale or LSI Logic, but the company plans to build its future design systems on OpenAccess, said Joe Morrell, systems architect for synthesis and design development at IBM. He also serves as co-chief architect of the OpenAccess change team.

File transfer burden

Morrell said that file transfers put a burden on IBM design groups, and they consume much of the company's tool development resources. An in-memory data exchange, made possible by OpenAccess, will eliminate a lot of problems, he said. Thus, IBM plans to migrate its tools to OpenAccess and hopes to build a system in which there are no file exchanges and all tools run off the OpenAccess database, Morrell said. But this work must proceed in stages, he said.

IBM hasn't converted any production flows yet, but the intent is strong--and the message to EDA vendors who don't support OpenAccess is clear: "We believe OpenAccess adoption is key to our continued success," Morrell said. "It will be extremely difficult for us to consider adding key tools that are not running on OpenAccess to our methodology."

- Richard Goering

EE Times