Verification Horizons BLOG

This blog will provide an online forum to provide weekly updates on concepts, values, standards, methodologies and examples to assist with the understanding of what advanced functional verification technologies can do and how to most effectively apply them. We're looking forward to your comments and suggestions on the posts to make this a useful tool.

9 October, 2014

DVCon India, held in September 2014 in Bangalore, built on the Indian SystemC User Group meeting events and added a Design & Verification track to its popular system-level design (ESL) track that has been popular for many years.  The main stage played host to the keynote presentations, opening ceremonies and best paper and poster awards.

Several DVCon India keynote presentations, which I will go into more depth later touched on emerging use of virtual platforms in system design and the growing impact India has on design verification.  In particular, Mentor’s CEO, Wally Rhines contrasted Wilson Research survey data on design verification from India and the rest of the world.  A strong adoption of SystemVerilog and its popular methodology, the Universal Verification Methodology (UVM) was clear from the survey results Wally shared.

But even beyond SystemVerilog and UVM, the discuss of what could come next anchored the first day of DVCon India discussion on Accellera’s exploration of “portable stimulus.”  Accellera has a group exploring if the industry is ready to start a standards project on this concept.  And the first day when DVCon India attendees were offered an opportunity to learn about this, the multi-company (Mentor Graphics, Breker & CVC) tutorial on the topic was standing room only.

DVCon Europe – The Stage is Set!

A tutorial slot at DVCon Europe will be devoted to the same topic that was popular at DVCon India.  For DVCon Europe attendees, you will find Tutorial T9, “Creating Portable Tests with a Graph-Based Test Specification” will cover this topic.  Technical representatives from Mentor Graphics and Breker will cover aspects of portable stimulus and offer examples of how it can work.  And early application of the technology will be covered by a representative from IBM.  To cover the topic appropriately, we have modified the presenters listed in the official printed program and full details are available online.  The presenters will be, in this order:

  • Holger Horbach, IBM, Germany
  • Frederic Krampac, Breker, France
  • Staffan Berg, Mentor Graphics, Sweden

Please join us for this tutorial and ensuing conversation and discussion.  Verification productivity is a pressing issue and our ability to better control and create stimulus is a step in the direction to address the verification challenges we all face.

One last note, the concept of “portable stimulus” is language agnostic so no matter which language you use for design and verification, the intention is this technology will be able to help.   The tutorial will help you understand how using a graph-based approach enables the highest degree of verification re-use, from IP block to sub-system to full-system level verification. You will see how it supports verification in SystemVerilog, Verilog, VHDL, C, C/C++, assembly, and even other non-traditional base languages. And it also can be extended from simulation to emulation to FPGA prototyping, and even silicon validation.

I look forward to seeing you at DVCon Europe in Munich!  And if you have not yet registered, please do so to secure your seat.

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12 September, 2014

Verification engineers spend lots of time creating tests. In fact, creating enough tests to verify the design functionality consistently tops the list of verification challenges, according to periodic surveys of our customers.

top_verification_challenges

Top Verification Challenges

One challenge in test creation is that verification occurs in multiple environments. For high-level models, verification might be performed in a SystemC environment. Unit-level verification often occurs in a SystemVerilog UVM environment. At the SoC level, the presence of embedded processor cores means embedded software must be part of the verification picture.

Writing specific tests for each environment only exacerbates the “creating enough tests” problem. Besides, different environments offer different levels of automation for test creation. For example, embedded software environments offer no help in creating tests more productively or creating more comprehensive tests – it’s directed tests all the way.

Portable graph-based stimulus brings advanced and highly-productive stimulus modeling techniques to a wide range of verification languages and environments – from automating sequences and virtual sequences in SystemVerilog to creating automated stimulus in VHDL. From verifying C and SystemC designs for high-level synthesis to automating software-driven test scenarios running on embedded processor cores.

If you are attending either DVCon India or DVCon Europe and are interested in how graph-based portable stimulus can boost your test-creation productivity, please consider attending the graph-based portable stimulus tutorial. Links to the respective conference programs are below.

DVCon India Conference Program: http://dvcon-india.org/conf/program-at-a-glance/

DVCon Europe Conference Program: http://dvcon-europe.org/wp-content/uploads/2014/09/dvcon-europe-advance-program-9-4-2014.pdf

11 September, 2014

From those just beginning to study electronic systems design to the practicing engineer, this is the time of the year when those taking their first steps to learn VHDL, Verilog/SystemVerilog join the academic “back to school” crowd and those who are using design & verification languages in practice are honing skills at industry events around the world.

A new academic year has started and the Mentor Higher Education Program (HEP) is well set to help students at more than 1200 colleges and universities secure access to the same commercial tools and technology used by industry.  It is a real win-win when students learn using the same tools they will use after graduating.  Early exposure and use means better skilled and productive engineers for employers.

The functional verification team at Mentor Graphics knows that many students would prefer to have a local copy of ModelSim on their personal computer to do their course work and smaller projects as they learn VHDL or Verilog.  To help facilitate that we make the ModelSim PE Student Edition available for download without charge.  More than 10,000 students use ModelSim PE Student Edition around the world now in addition to our commercial grade tools they can access in their university labs.

For the practicing engineer, the Verification Academy offers an online community of more than 25,000 design and verification engineers that exchange ideas on a wide variety issues across the numerous standards and methodologies.  If you are not a member of the Verification Academy, I recommend you join.  You will also find the Verification Academy at DAC for one-on-one discussions and even more recently Verification Academy Live daylong seminars which came to Austin and which will be in Santa Clara – as of the writing of this blog.  There is still time to register for the Santa Clara event and I invite you to attend.

As design and verification is global, Accellera realized that DVCon should explore the needs of the global design and verification engineer population as well.  For 2014, DVCon Europe and DVCon India were born from an already successful running SystemC User Group events.  These user-led conferences will be held so engineers in these areas can more easily come together to share experiences and knowledge to ultimately become more productive.

Students and practicing engineers alike can benefit from fee-free access to some of the popular IEEE EDA standards.   While I don’t think reading them alone is the ultimate way to educate yourself, they make great companions to daily design and verification activities.  Accellera has worked with the IEEE to place several EDA standards in the IEEE Standards Association’s “Get™” program.  Almost 16,000 copies of the SystemC standard (1666) and just about the same number of SystemVerilog standards (1800) have been downloaded as of the end of August 2014.  Have you download your free copies yet?

The chart below shows the distribution of nearly 45,000 downloads which have occurred since 2010.  Stay tuned for breaking news on some updates to the EDA standards in the Get program.  When updated, they will replace the versions available now.  So if you want to have the current versions and the ones to come out shortly, you better download your copies now.  If the electronic version is not sufficient for you, the IEEE continues to sell printed versions.

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From students to practicing engineers, the season of learning has started.  I encourage you to find your right venue or style of learning and connect with others to advance and improve your design and verification productivity.

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20 August, 2014

The ever popular Accellera Design & Verification Conference held annually in Silicon Valley is going global.  Accellera System Initiative has expanded many of its SystemC user group events to be more inclusive of other Accellera and IEEE standards.  In doing so, the local organizers of these events have moved to adopt the popular DVCon USA style to organize their events to include this large complement of standards.  If you want to attend, participate or contribute to the events, follow the links as shared below.

Mentor Graphics is excited to participate and sponsor these user-led events with a keynote address, technical paper presentations and educational tutorials.  We look forward to see you in September for DVCon India in Bangalore and in October for DVCon Europe in Munich.

DVCon Europe (14-15 October 2014 | Munich, Germany) will target the application of standardized languages, tools, and methodologies for the design and verification of electronic systems and integrated circuits. The two day event will feature tutorials on the first day and technical paper presentations and poster sessions on the second day.  The DVCon Europe program list the details of the conference.  It is collocated with the annual Forum on Design Languages (FDL), which runs from 14-16 October 2014 in case you want to extend your stay for an extra third day.

At DVCon Europe Mentor Graphics is collaborating with our industry peers and users on a tutorial titled Enabling Energy-Aware System Level Design with UPF-Based System Level Power Models. As power has become one of the major concerns in design equaling those of feature, function and performance, more advances are needed to address system power challenges.  The tutorial will explore the use of IEEE Std. 1801™ (UPF) and how design and verification flows can best use it.

Mentor Graphics will also sponsor a tutorial titled Creating Portable Tests with a Graph-Based Test Specification.  It will cover an overview of a graph-based test description language that raises the level of verification abstraction to address system level challenges. This technology is being used by many successful verification teams around the world today and it is the technology we have committed to help build a new standard upon in Accellera.

DVCon India (25-26 September 2014 | Bangalore, India) is the first year of the transition of the popular Indian SystemC User Group (ISCUG) meeting into an event that expands to cover topics that bring together all the stakeholder involved in design and verification of IP, SoC, ASIC, FPGA and system level solutions.   The event is over two days with common sessions in the morning for keynote addresses.  The attendees will then break into an ESL track and Design & Verification track for focused sessions.

Mentor Graphics will sponsor a tutorial session as well as host the keynote presentation by Mentor Graphics CEO, Dr. Walden C. Rhines.  Dr. Rhines will review recent Wilson Research Group study results on the ongoing convergence of SoC design practices towards a common methodology, independent of specify tools being use. In this keynote, Dr. Rhines identifies the common attributes of SoC methodology that are emerging, and will highlight specific capability enablers for the further optimization of SoC design verification.

Registration for both events is now open and I hope you have time in your calendar to make it there.  Both events will have an exhibition area where you can also catch up on recent updates to our products and discuss what you think should be added next.  The Mentor Graphics team looks forward to meeting you there!

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12 August, 2014

As some of you may have seen, we release a great DAC edition of Verification Horizons back in June. Unfortunately, we were so focused on preparing for a great Verification Academy Booth at DACBoothPic
that I completely forgot to blog about the issue! Well, as the saying goes, “better late than never.”  In particular, I’d like to call your attention to two articles.

The first is “Best Practices for FPGA and ASIC Development” by my Mentor colleagues Josh Rensch and John Boone, in which they take you through the four development phases of an FPGA project. By separating the process into distinct PLAN, EXECUTE, VERIFY and SUPPORT phases, Josh and John help you establish a manageable process that you can apply to your next project. The key is to identify the techniques, or specific activities, that will be used at each phase, and establish a rigorous set of deliverables for each phase. Just like clear interface specs are necessary for two design blocks to be able to talk to each other, clear deliverables at each phase of the process let different groups work together efficiently to create a robust and well-verified design.

The other article I wanted to point out to you is “Merging SystemVerilog Covergroups by Example” by our friend Eldon Nelson, a verification engineer at Micron Technology. This article explores the options available when defining and using covergroups, establishing some important guidelines that will help you get the most useful information when multiple instances of covergroups are merged together. Be sure to check it out.

The other articles in the issue are:

9 July, 2014

Accellera has announced the completion of a multi-year effort to update its latest edition of the Universal Verification Methodology (UVM).  In completing this effort, the UVM 1.2 Class Reference Document was approved as an Accellera standard and the UVM Working Group has supplied an accompanying open-source reference implementation.  Questa supports UVM 1.2.

In addition to the resources you can download from Accellera, additional information on UVM 1.2 can be found at the Verification AcademyHTML documentation can easily be found at the Verification Academy too.

If you are a user of UVM 1.1 and have not been part of the UVM 1.2 development effort, you should know your peers have been busy the past few years since the stabilization and completion of UVM 1.1 to drive global adoption of UVM and to add, enhance and extend UVM.  In UVM 1.2 Messaging is now object-oriented, Sequences can automatically raise and drop objects, the register layer can now control transaction order within bursts and numerous bugs in UVM 1.1 have been fixed to improve quality.

Backward Incompatibility

All these changes come with a cost to the current UVM 1.1 user community.  When Accellera announced UVM 1.2 availability, it also disclosed some of the new features introduce backward incompatibility.  To reduce those issues, Accellera is making release notes and a one way conversion script part of the UVM 1.2 kit to ease the migration path forward.

If you follow the Verification Academy Cookbook rules, you will probably not see any impact from the backward compatibility issues.  And if you control your total verification environment, you will probably find it simpler to migrate forward as well.  Those who depend on outside resources will need to make sure those resources (like Verification IP) migrate forward to UVM 1.2 so you can migrate forward to UVM 1.2.  Mixing UVM 1.1 and UVM 1.2 was not considered by the Accellera UVM Working Group and is fraught with unknown issues.  We consider the migration an all or nothing proposition.  If you have multi-division, multi-company projects underway, it would be prudent to plan you move to UVM 1.2 with care at the conclusion of projects and when all suppliers and participating teams can migrate to UVM 1.2.

Public Review Period

Accellera seeks your input and feedback on UVM 1.2.  To support this, a public review forum on the Accellera website has been established to allow users to catalog issues, ask questions and generally offer feedback to help improve UVM 1.2 quality.

The public review process will end on October 1, 2014.  We encourage users to take the time now to test UVM 1.2 in their own environments and share their feedback to expidite the migration to UVM 1.2.

Path to IEEE

Public feedback will be taken into account along with further Accellera member testing to update UVM 1.2 prior to a committed hand-off to the IEEE for further standardization there later this year.  As this path unfolds, I will share updates on the standardization effort in the IEEE.

Verification Academy DAC 2014 UVM 1.2 Presentation

You will find many resources around the world on UVM 1.2.  At DAC 2014, the Verification Academy booth sponsored a session on UVM 1.2 titled  “UVM: What’s New, What’s Next, and Why You Care.”  If you did not attend DAC, you can still download the presentation and watch a video replay of it if you are a Verification Academy “full access” member (free registration required; restrictions apply).

The presentation by Tom Fitzpatrick goes into detail on the UVM 1.2 topic.  Importantly in Tom’s presentation is a discussion about what you should care about today.  You may find that software is a big issue and that his thesis challenges one to ask if UVM 1.2 is stuck in the past rather than addressing what should be addressed next.  I invite you to download the presentation and watch the video and share with me your thoughts. What do you think?

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29 May, 2014

Verification engineers put lots of effort into writing and tuning constraints for random stimulus. It’s critical that the constraints correctly express the valid relationships between the stimulus variables. Otherwise, invalid stimulus will be generated or, worse, important valid combinations of stimulus will not be generated.
When it comes to bug hunting, running open-loop random stimulus is recognized as a good way to ensure that cases are exercised that the verification engineer wouldn’t intuitively think of. However, the very constraints that verification engineers work so hard to perfect get in the way of this goal by introducing random-resistant cases – value combinations that have an extremely low probability of occurring.

Consider the SystemVerilog class shown in Figure 1 below to see just what a dramatic effect a few constraints can have on the cases that a constraint solver produces. One simple constraint skews the entire random distribution!

Figure 1: Constraints skew random distribution

Figure 1: Constraints skew random distribution

This type of skewed distribution is easy to see and adjust for when the variable combinations are monitored by functional coverage. However, let’s face it, the whole premise of using random stimulus to find bugs is that random generation will produce cases that we didn’t think of (and, thus, didn’t create functional coverage for).
What if the very constraints that engineers spend so much time creating and refining could actually help ensure that corner cases are hit? If you’re attending DAC this year, come see a poster paper titled “Strategy-Driven Stimulus Generation: Constraint-Guided Test Selection” that proposes an approach that leverages the constraint description to identify high-value stimulus values and get more value from bug-hunting simulation runs:

Session Title: Designer/IP Track Poster Session – Wednesday
Session Number: 302
Presentation Title: Strategy-Driven Generation: Constraint-Guided Test Selection
Date: Wednesday, 6/4/2014 12:00-1:30PM
Room: 100

How do you ensure that your random simulations continue to provide incremental value, and aren’t just testing the same thing over and over again?

7 May, 2014

My Feb. 4 post introduced Mentor Graphics’ three-step FPGA verification process intended to help design teams get out of the reprogrammable lab more effectively. Since then, I’ve engaged FPGA vendors, design managers and engineers to explain the process, paying special attention to the merits and technical detail for injecting automation into any FPGA verification environment, the hallmark of Mentor’s process. The feedback from these conversations helped me to develop a series of technical webinars, now available for free and on-demand. Check them out and let us know what you think in the comments below. My hope is the webinars might serve as a starting point for your own conversations on verification of FPGAs, demand for which seems to continue to grow as process nodes shrink.

Injecting Automation into Verification – FPGA Market Trends

Injecting Automation into Verification – Code Coverage

Injecting Automation into Verification – Assertions

Injecting Automation into Verification – Improved Throughput

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25 April, 2014

DVCon 2014 Conference Proceedings Published

2014DVCon_logoWith record attendance announced for DVCon 2014, one might wonder if there is really a need to put some of the “Accellera Day” tutorial videos online.  With more than 1,000 professionals attending in some capacity, it would be easy to conclude that everyone that needs to know about UVM and the developments on the updated version to it, probably know.  Looking at just the LinkedIn design and verification forums one will realize there are 10’s of thousands who would have benefited if they had attended DVCon.  Thus, sharing this information more broadly is in order.

UVM Tutorial Video

UVM – What’s Now and What’s Next” is the tittle of the DVCon 2014 tutorial on UVM.  It covered use cases and pragmatic topics of the current UVM 1.1 standard as well as advanced topics for the next update, UVM 1.2.  The presenters covered sequence creation, register layer use, TLM-based communication, test execution, run-time phases and messaging enhancements.

The tutorial was split into five separate sections delivered by five speakers as follows:

  • Working Group Update: Adam Sherer, Accellera (7 min.)
  • Overview and Library Concepts: John Aynsley, Doulos (36 min.)
  • Stimulus Generation: Shawn Honess, Synopsys (21 min.)
  • UVM Register Layer: Tom Fitzpatrick, Mentor Graphics (36 min.)
  • UVM 1.2 Introduction: Uwe Simm, Cadence Design Systems (25 min.)

You can find out more information about the online tutorial videos hereRegistration is required, but there is no charge for access.  Once you have registered, you will get links to each of the five sections.  You can stream them or download them for offline access as you wish.  They are suitable for viewing on your computer or mobile devices.

DVCon 2014 Proceedings

DVCon 2014 was a full conference; it was more than just the the Accellera Day UVM Tutorial.  And in keeping with DVCon tradition, the conference proceedings are made available to all several months after the conference without charge.  If you visit the DVCon history area, you will find the 2014 proceedings have been published.  What I like about the DVCon proceedings it not only are the papers published, but the slides that were presented at the conference will often accompany the paper.

As an example, if you were interested in the DVCon 2014 Best Oral Presentation paper and presentation (Kelly D. Larson from NVIDIA on , “Determining Test Quality through Dynamic Runtime Monitoring of SystemVerilog Assertions” by the way), you will now find both the paper and presentation available online here.

For all those who did not make it to DVCon 2014, or who were there and could not see everything, the proceedings are now online and the first of the Accellera Day tutorials videos is published. Accellera is busy readying its other tutorial videos.  I’ll share information on their availability as they appear in the weeks and months ahead.

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10 April, 2014

Its always fun to take the wraps off of solutions we have been hard at work developing.  The global team of Mentor Graphics engineers have spent considerable time and energy to bring the next level of SoC design and verification productivity to what seems to be a never ending response to Moore’s Law.  As silicon feature sizes get smaller, design sizes get larger and the verification problem mushrooms.  But you know that.  These changes are the constants that drive the need for continued innovation.  Our next level of innovation for design verification is embodied in the Mentor Enterprise Verification Platform (EVP) which we recently announced.

Gary Smith recently published Keeping Up with the Emulation Market, and lays out the fact that verification platforms are unifying with emulation now a pivotal element, not just for microprocessor design success, but for Multi-Platform Based SoC design success as well.  The need to bring software debug into the loop with early hardware concepts is a verification challenge that must be supported as well.  Pradeep Chakraborty reported on the point made by Anil Gupta of Applied Micro at the UVM 1.2 Day in Bangalore where Anil implored “Think about the block, the subsystem and the top.”  The point made was software is often overlooked or under tested prior to committing to hardware implementation implying that our focus on UVM leaves us to verify no higher than where UVM takes us – and that is not the “top” of the SoC that mandates software be part of the verification plan.

Path to Success

With the Mentor EVP, we do address these issues.  We bring simulation and emulation together in a unified platform.  Software debug on conceptual hardware is supported to address verification at the “top.”  And even as Gary’s report concludes with a wonder about how easy access to emulation will be supported for the masses.  That too is solved in the Mentor EVP using VirtuaLAB that can be hosted in data centers along with the emulator vs. complex, one-off lab setups that lock an emulator to a design and lock out your global team of software developers from collaborating.  The Mentor EVP moves to emulation for the masses in a 24×7 world.

With big designs comes big data and complex debug tasks.  These complex debug tasks are all easily handled by the new Mentor Visualizer Debug Environment that has native UVM and SystemVerilog class-based debug capabilities and low-power UPF debug support to easily pinpoint design errors. All of this works in both interactive and post-simulation modes for simulation and emulation.  To keep the software team productive, and get to SoC signoff sooner, the innovative and new Veloce OS3 global emulation resourcing technology moves software debug think-time offline to Mentor’s Codelink software debug tool.

And there’s more!  But I’ll leave that for you to discover.  When you have time, visit us here, to learn more about the Mentor Enterprise Verification Platform.

Path to Standards

As the move to support Multi-Platform Based SoC evolves, so do the standards that underpin it.  And as I’ve reported on the comments of others in this blog – and the understanding from our experience that UVM can only go so far in Multi-Platform Based SoC verification – we concluded the time is right for the industry to explore the need for new standards.

We announced at DVCon 2014 an offer to take our graph-based test specification into an Accellera committee to help move beyond the limitations today’s standards have.  As our investment in tools, technology and platforms continues, we are keenly aware users want their design and verification data to be as portable as possible.  The Accellera user community members echoed the need to discuss portable stimulus that can take you up and down the design hierarchy from block, to subsystem, to system (“top”) and support the concurrent design of hardware and software.

In support of this, Accellera approved the formation of a Portable Stimulus Specification Proposed Working Group (PWG) to study the validity and need for a portable stimulus specification.  To that end, join me at the kickoff meeting to launch this activity on Wednesday, May 7, 2014 from 10:00am to 4:00pm Pacific time at the offices of Mentor Graphics in Fremont, CA USA.  If you would to attend, or you would  like time on the agenda to discuss technology that would advance the development of a Portable Stimulus Specification or discuss your objectives/requirements for this group, contact me and I will put you in touch with the meeting organizer.  Accellera PWG meetings are open to all and do not require Accellera membership status to attend.

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