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Posts Tagged ‘realistic use case’

The Power and Simplicity of Path Constraints

Wednesday, May 25th, 2016

Last week on The Breker Trekker, we talked about path constraints and how they differ from other kinds of constraints commonly used in SoC design and verification. Our whole approach to verification is based on graph-based scenario models, and constraints on the paths through the graph are a natural way to control how our Trek family of products automatically generates test cases. It’s easy to eliminate some paths, focus on others, or bias the randomization of selections. We believe that path constraints should be a part of any portable stimulus solution that meets the forthcoming Accellera standard.

We have heard some people in the industry argue that path constraints are not needed, and that value constraints would suffice. While we agree that value constraints are a familiar concept from the UVM and other constrained-random approaches, we do not feel that they are the best way to control the scenarios generated from a portable stimulus model. In today’s post we will expand on the example from last week and show how path constraints can handle a more complex design better than value constraints.

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Path Constraints for Graphs and Portable Stimulus

Thursday, May 19th, 2016

As engineers, we take great pride in defining our terms carefully and using them precisely to try to avoid ambiguity or confusion. Many engineering specifications start with a glossary of terms and sometimes even a taxonomy showing how they are related. Sometimes though, natural language being inherently ambiguous, we find that we have overloaded the meaning of certain words in a way that can lead to precisely the confusion we seek to avoid.

One such word is “constraint” because it is used in several different contexts in chip design and verification. In today’s post we would like to discuss path constraints on a graph-based scenario model. We will explain how they differ from other forms of constraints and why path constraints are essential for any portable stimulus solution, including the Trek family of products from Breker.

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SoCs in Space!

Wednesday, May 11th, 2016

The title of last week’s post was a play on a Mark Twain quote. This week I draw from a more contemporary source: The Muppets. Some episodes of the legendary family TV show featured a skit called “Pigs in Space.” In my head I’m reading “SoCs in Space!” with the same booming intonation used on the show for “Pigs in Space” to lead into a somewhat more serious discussion about the use of advanced chips in extreme conditions.

My prompt for this particular post came not from TV, but from an announcement yesterday that VORAGO Technologies is offering an ARM-based microcontroller (MCU) “designed specifically for radiation and extreme temperature operation without up-screening.” In other words, they ship an MCU that’s ready to use in such traditionally challenging environments as automobiles and industrial controllers as well as, yes, space. That got me thinking about even more complex chips such as SoCs and the extreme conditions they might have to face.

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The Report of Simulation’s Death Was an Exaggeration

Thursday, May 5th, 2016

With a nod to Mark Twain, this week I’d like to comment on a recent three-part series with the provocative title “Are Simulation’s Days Numbered?” The articles were transcribed from one of the “experts at the table” events that SemiconductorEngineering does so well. Breker wasn’t involved in this particular roundtable, but I enjoyed reading the series and found that it stirred up some thoughts. As a blogger, of course I’m going to share them with you and I hope you enjoy them in turn.

Let’s get this out of the way immediately: in three parts and more than 5,000 words, there was no mention of portable stimulus. That might not seem too surprising given the title, but in fact verification portability both from IP to system and from simulation to hardware arose during the discussion. So I’ll comment on that but, given my background as a vendor of formal EDA tools and reusable IP blocks, there are a few other topics that also piqued my interest.

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A Snapshot Update on the Accellera Portable Stimulus Effort

Wednesday, March 16th, 2016

As all of our regular readers are aware, the software-driven SoC verification space pioneered by Breker is becoming more of a mainstream approach every day. One good barometer for the industry shift now underway is the standardization effort in progress within the Accellera Portable Stimulus Working Group (PSWG). The amount of interest in this standard has skyrocketed recently, and portable stimulus was a hot topic at the Design and Verification Conference and Exhibition (DVCon) two weeks ago.

As we promised when we first began discussing the PSWG, we don’t believe in sharing internal details of standardization work in a public blog. However, the group was offered a slot to present an update at an Accellera-sponsored lunch during DVCon. So the PSWG put together a set of slides with information to share publicly and Vice-Chair Tom Fitzpatrick of Mentor did a nice job of presenting them. For those of you who could not attend, we’ll summarize the current status in today’s blog post.

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DVCon Panel: Trying to Define the ESL Shapeshifter

Wednesday, March 9th, 2016

In last week’s post on The Breker Trekker we summarized activities at the Design and Verification Conference and Exhibition (DVCon) in San Jose, including a brief mention of the “Redefining ESL” panel on Wednesday morning. I attended this session and took detailed notes in anticipation of blogging about it, but in the process gave some thought to my own opinions about the electronic system-level (ESL) domain and how they intersect with those of the panel participants.

The panel was organized by Dave Kelf of OneSpin Solutions and PR guru Nanette Collins, and moderated by Brian Bailey of SemiconductorEngineering. Brian is a long-time observer of the ESL market so I expected him to ask some tough questions. He opened by remarking that the term is generally credited to the late EDA analyst Gary Smith. Many of us who knew Gary sometimes teased him a bit on his regular pronouncements that “this will be the year of ESL.”

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Portable Stimulus Was Front and Center at this Year’s DVCon

Thursday, March 3rd, 2016

We’ve just returned from our most important trade show of the year: the Design and Verification Conference and Exhibition (DVCon) in San Jose. Sure, DAC is a bigger show, but it covers all of EDA and so lacks the front-end digital focus of DVCon. We previewed the event over our last few blog posts and today we’d like to summarize what happened and make a prediction or two about how this particular DVCon will affect the industry.

The biggest news for us was that portable stimulus seemed to be on everyone’s lips this year. Many of the engineers who stopped by to visit our booth had heard the term and were aware that the Accellera Portable Stimulus Working Group (PSWG) is developing a standard. If they didn’t know what portable stimulus was, they almost surely knew by the end of the show.

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Automatically Generating Interacting, Self-Checking Test Cases for 144 CPU Cores

Wednesday, February 24th, 2016

We hope that the title of this blog post piqued your interest, because we don’t believe that we’ve seen anyone anywhere claiming to do automated multi-SoC verification at this level. Two weeks ago, we previewed next week’s Design and Verification Conference and Exhibition (DVCon) in San Jose. We highlighted one particular talk being co-presented by Breker and Cavium on “Using Portable Stimulus to Verify Cache Coherency in a Many-Core SoC” in the 9:00-10:30 a.m. session on Tuesday, March 1.

We teased you with the statement that this talk will describe “generating test cases for a multi-SoC configuration with well over 100 cores” and it’s time to tell you a bit more now that we have issued a press release on our project with Cavium. Of course, we need to reserve some of the details for the paper in the DVCon proceedings and the talk itself so that new material is being presented at the conference. We heartily encourage you at attend the show and hear for yourself.

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Why Is Cache Coherency So Hard to Verify?

Friday, February 19th, 2016

In last week’s post, we provided a preview of the program at the annual Design and Verification Conference and Exhibition (DVCon) in San Jose, coming up in ten days. We mentioned some of the interesting talks and other activities there, and focused in particular on “Using Portable Stimulus to Verify Cache Coherency in a Many-Core SoC” on Tuesday morning. The paper for this session was co-authored by Breker and Cavium, and both companies will present together at DVCon.

The paper and presentation describe the use of our Cache Coherency TrekApp and TrekSoC-Si to automatically generate self-checking, portable test cases for more than 100 CPU cores in a multi-SoC configuration in the Cavium bring-up lab. To set the stage for this story, today we’d like to revisit some of the reasons why cache coherency is so hard to verify and why an automated approach is the best solution.

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A Preview of the Upcoming DVCon in San Jose

Wednesday, February 10th, 2016

Regular readers of The Breker Trekker know that we like to preview, review, and dissect technical conferences and trade shows that are of interest to verification engineers. Perhaps the conference we’ve covered the most has been the annual Design and Verification Conference and Exhibition (DVCon) in San Jose. As far as we know, this is the biggest event anywhere focused on digital and system design and verification, a nice complement to the analog-ish DesignCon.

As a matter of fact, DVCon has become so successful that there are now regional conferences in India and Europe in addition to the U.S. show. We’ve strongly supported DVCon India, including serving for all three years on the Promotions Committee, and have participated in DVCon Europe as well. But those are a bit in the future; DVCon (U.S.) 2016 is coming up in a just a few weeks. The program is online now, so we thought we’d review it and suggest some sessions of possible interest.

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