PCIe has been widely adopted in the electronics industry since its first debut in 2003 (PCIe 1.0 standard release) for wide breach of applications, from Data Center Server, Networking, to Mobile, AI/ML, Automotive, IoT, and many others…. It’s a versatile, high-performance, robust, mature interconnect standard with full “backward compatibility” (e.g., a PCIe 3.0 device can still function well in a PCIe 4.0 system) which enables a solid and strong PCIe eco-system in the industry.  While the market, so as the users,  are enjoying the systems, e.g., desktop/laptop, powered (or to be more specific: “bridged”) by PCIe 3.0 since 2010, the industry is pushing hard for the PCIe 4.0 eco-system enablement. Earlier this year, AMD announced it X570 chipset would support the PCIe 4.0 interface and Phison also introduced the world’s first PCIe 4.0 SSD.

On the standard evolution front, the official PCIe 5.0 came out in May 2019, doubling the data rate to 32GT/s from 16GT/s in PCIe 4.0. The PCIe 6.0 standard will be released in 2021 based on the announcement made by PCI-SIG in June’19 with the goal to further double the data rate to 64GT/s with incorporating the PAM4 coding.

PCIe Protocol Evolution

Having said that, is the latest generation of PCIe always desired?  

My answer would be positive. Just like car maker/enthusiast has kept pursuing faster car in the history, there is no doubt that these speed enhancements/upgrades in the electronic world certainly provide a tremendous benefit for especially those applications craving the most throughput, such as Data center, HPC, Networking, Cloud and AI applications.   

But, does every application have to opt for the fastest speed (bandwidth)? My view would be leaning toward “Not really”. Just like we don’t need a 3-second sport car (meaning 0-60mph acceleration < 3s) for daily commute though it would certainly spice some driving fun on the road, but it may not be "the best fit" for most of commuters.

There are applications still well satisfied with PCIe 3.0 (or even older PCIe 2.0) for its best performance and cost balance.  Those applications include, but not limit to, IoT/consumer, Edge AI, SSD (non-enterprise),…etc. They typically need to make trade-off in between the cost, power consumption (especially battery powered), flexibility on changing product features, and time-to-market (TTM). To address such type of market needs, Cadence also offers an PPA (Performance, Power, Area) optimized PCIe 3.0 solution in addition to its high-performance PCIe 4.0 product line.

Cadence PCIe 3.0 PHY Solution (with Multi-Protocol Multi-Link feature)

With leveraging the multi-protocol SerDes implementation, the same Cadence PHY IP support multi-protocol and multi-link operation. Such a multi-protocol enabled PHY gives the SoC developers the optimum flexibility to integrate multiple commonly used interface protocols (e.g., PCIe 3.0 + USB 3.0) with using only a single PHY design.  This would largely save the product development time (faster TTM), reduce the risk of using multiple different PHY instances (for different protocol needs), and with the configurability to enable different product features/protocols.

Some people might say PCIe 3.0 era has gone. I was not quite yet being convinced as I still see its potential to shine a lot of market use cases. What do you think?

More Information

For more information on Cadence's PCIe IP offerings, see our PCI Express page.

For more information on PCIe in general, and on the various PCI standards, see the PCI-SIG website.

Related Posts

• Blog: PCIe Gen4: It’s Official, We’re Compliant
• Blog: The PCIe 4.0 Era Continues at PCI-SIG Developers Conference 2016
• Blog: Cadence PCIe Solutions: Configurable, Compliant, and Low Power

I’m coming to the party late—last weekend, for the first but not the last time, I watched Manish Acharya’s comedy, Loins of Punjab Presents. Behan____, what a film! 

I will not rehearse the synopsis or plot, partly because of the lateness of the hour, but also because it is available here. Instead, let me note quickly that the comedy keeps ticking, and the attention to detail in all matters, from the plot to the casting, makes this film a pleasure to watch.

Let me use one scene to make a point about where the film is coming from. Ishitta Sharma, playing a demure, Gujju girl called Preeti Patel, is one of the competitors in the Desi Idol competition in New Jersey. We have watched her sing beautifully, and we have watched her stay silent, eyes downcast, as her family-members make fools of themselves. But there’s a moment later in the film, when an older, wily competitor, played with classy ease by Shabana Azmi, tries to manipulate her. And suddenly, in the blink of an eye, Preeti Patel turns upon the Shabana character. It’s as if she always had a dagger hiding in her hand.

When I saw that, I thought that there was a similar strength in the movie I was watching. It’s all laughs but it has a quicksilver intelligence within. It is a declaration of independence by the desi diaspora—and what is great is that it celebrates this freedom by mocking, and loving, almost everything in sight.

Rave Out © 2007 IndiaUncut.com. All rights reserved.
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Literate Indians should be familiar with Ashis Nandy’s remark: “Cricket is an Indian game accidentally discovered by the English.“ A Trinidadian Indian by the name of Chuck Ramkissoon, in Joseph O’Neill’s superbly inflected novel “Netherland”, is also fond of making bold pronouncements on the behalf of the game he wants to introduce to the U.S. “I’m saying that people, all people, Americans, whoever, are at their most civilized when they’re playing cricket. What’s the first thing that happens when Pakistan and India make peace? They play a cricket match…”

It’s now my turn to be bold: “Netherland” is more of an Indian novel than the recent, much feted, Indian fiction. This is not only because O’Neill’s novel feeds our national obsession with the game. Nor even its exquisite description of what transpires on the playing field: “…. where the white-clad ring of infielders, swanning figures on the vast oval, again and again converge in unison toward the batsman and again and again scatter back to their starting points, a repetition of pulmonary rhythm, as if the field breathed through its luminous visitors.” No. My pronouncement is based on the fact that the Indian characters in the book are highly individualized and yet fully global in their identity. “Netherland” is not a sociological-historical epic thesis, nor is it a shallow, cynical report on injustice in the hinterland. Rich in observation, reporting as much on the interior life as on the life outside, it is a captivating literary achievement. A masterpiece.

Rave Out © 2007 IndiaUncut.com. All rights reserved.
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Who used to be known as Dileep Kumar, and is now married to Saira Banu?

Workoutable © 2007 IndiaUncut.com. All rights reserved.
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In Texas Hold’em Poker, which hand is known as ‘six tits’?

Workoutable © 2007 IndiaUncut.com. All rights reserved.
India Uncut * The IU Blog * Rave Out * Extrowords * Workoutable * Linkastic

This is the 19th installment of The Rationalist, my column for the Times of India.

A friend of mine was very impressed by the interview Narendra Modi granted last week to Akshay Kumar. ‘Such a charming man, such great work ethic,’ he gushed. ‘He is the kind of uncle I would want my kids to have.’ And then, in the same breath, he asked, ‘How can such a good man be such a bad prime minister?”

I don’t want to be uncharitable and suggest that Modi’s image is entirely manufactured, so let’s take the interview at face value. Let’s also grant Modi his claims about the purity of his neeyat (intentions), and reframe the question this way: when it comes to public policy, why do good intentions often lead to bad outcomes? To attempt an answer, I’ll refer to a story a friend of mine, who knows Modi well, once told me about him. 

Modi was chilling with his friends at home more than a decade ago, and told them an incident from his childhood. His mother was ill once, and the young Narendra was tending to her. The heat was enervating, so the boy went to the switchboard to switch on the fan. But there was no electricity. My friend said that as he told this story, Modi’s eyes filled with tears. Even after all these years, he was moved by the memory.

My friend used this story to make the point that Modi’s vision of the world is experiential. If he experiences something, he understands it. When he became chief minister of Gujarat, he made it his stated mission to get reliable electricity to every part of Gujarat. No doubt this was shaped by the time he flicked a switch as a young boy and the fan did not budge. Similarly, he has given importance to things like roads and cleanliness, since he would have experienced the impact of those as a young man.

My term for him, inspired by Rajat Kapoor’s 2014 film, is ‘the ankhon dekhi prime minister’. At one level, this is a good thing. He sees a problem and works for the rest of his life to solve it. But what of things he cannot experience?

The economy is a complex beast, as is society itself, and beyond a certain level, you need to grasp abstract concepts to understand how the world works. You cannot experience them. For example, spontaneous order, or the idea that society and markets, like language, cannot be centrally directed or planned. Or the positive-sum nature of things, which is the engine of our prosperity: the idea that every transaction is a win-win game, and that for one person to win, another does not have to lose. Or, indeed, respect for individual rights and free speech.

One understands abstract concepts by reading about them, understanding them, applying them to the real world. Modi is not known to be a reader, and this is not his fault. Given his background, it is a near-miracle that he has made it this far. He wasn’t born into a home with a reading culture, and did not have either the resources or the time when he was young to devote to reading. The only way he could learn about the world, thus, was by experiencing it.

There are two lessons here, one for Modi himself and others in his position, and another for everyone.

The lesson in this for Modi is a lesson for anyone who rises to such an important position, even if he is the smartest person in the world. That lesson is to have humility about the bounds of your knowledge, and to surround yourself with experts who can advise you well. Be driven by values and not confidence in your own knowledge. Gather intellectual giants around you, and stand on their shoulders.

Modi did not do this in the case of demonetisation, which he carried out against the advice of every expert he consulted. We all know the damage it caused to the economy.

The other learning from this is for all of us. How do we make sense of the world? By connecting dots. An ankhon-dekhi approach will get us very few dots, and our view of the world will be blurred and incomplete. The best way to gather more dots is reading. The more we read, the better we understand the world, and the better the decisions we take. When we can experience a thousand lives through books, why restrict ourselves to one?

A good man with noble intentions can make bad decisions with horrible consequences. The only way to hedge against this is by staying humble and reading more. So when you finish reading this piece, think of an unread book that you’d like to read today – and read it!

© 2007 IndiaUncut.com. All rights reserved.
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This is the 24th installment of The Rationalist, my column for the Times of India.

Back in the last decade, I was a cricket journalist for a few years. Then, around 12 years ago, I quit. I was jaded as hell. Every game seemed like déjà vu, nothing new, just another round on the treadmill. Although I would remember her fondly, I thought me and cricket were done.

And then I fell in love again. Cricket has changed in the last few years in glorious ways. There have been new ways of thinking about the game. There have been new ways of playing the game. Every season, new kinds of drama form, new nuances spring up into sight. This is true even of what had once seemed the dullest form of the game, one-day cricket. We are entering into a brave new world, and the team leading us there is England. No matter what happens in the World Cup final today – a single game involves a huge amount of luck – this England side are extraordinary. They are the bridge between eras, leading us into a Golden Age of Cricket.

I know that sounds hyperbolic, so let me stun you further by saying that I give the IPL credit for this. And now, having woken up you up with such a jolt on this lovely Sunday morning, let me explain.

Twenty20 cricket changed the game in two fundamental ways. Both ended up changing one-day cricket. The first was strategy.

When the first T20 games took place, teams applied an ODI template to innings-building: pinch-hit, build, slog. But this was not an optimal approach. In ODIs, teams have 11 players over 50 overs. In T20s, they have 11 players over 20 overs. The equation between resources and constraints is different. This means that the cost of a wicket goes down, and the cost of a dot ball goes up. Critically, it means that the value of aggression rises. A team need not follow the ODI template. In some instances, attacking for all 20 overs – or as I call it, ‘frontloading’ – may be optimal.

West Indies won the T20 World Cup in 2016 by doing just this, and England played similarly. And some sides began to realise was that they had been underestimating the value of aggression in one-day cricket as well.

The second fundamental way in which T20 cricket changed cricket was in terms of skills. The IPL and other leagues brought big money into the game. This changed incentives for budding cricketers. Relatively few people break into Test or ODI cricket, and play for their countries. A much wider pool can aspire to play T20 cricket – which also provides much more money. So it makes sense to spend the hundreds of hours you are in the nets honing T20 skills rather than Test match skills. Go to any nets practice, and you will find many more kids practising innovative aggressive strokes than playing the forward defensive.

As a result, batsmen today have a wider array of attacking strokes than earlier generations. Because every run counts more in T20 cricket, the standard of fielding has also shot up. And bowlers have also reacted to this by expanding their arsenal of tricks. Everyone has had to lift their game.

In one-day cricket, thus, two things have happened. One, there is better strategic understanding about the value of aggression. Two, batsmen are better equipped to act on the aggressive imperative. The game has continued to evolve.

Bowlers have reacted to this with greater aggression on their part, and this ongoing dialogue has been fascinating. The cricket writer Gideon Haigh once told me on my podcast that the 2015 World Cup featured a battle between T20 batting and Test match bowling.

This England team is the high watermark so far. Their aggression does not come from slogging. They bat with a combination of intent and skills that allows them to coast at 6-an-over, without needing to take too many risks. In normal conditions, thus, they can coast to 300 – any hitting they do beyond that is the bonus that takes them to 350 or 400. It’s a whole new level, illustrated by the fact that at one point a few days ago, they had seven consecutive scores of 300 to their name. Look at their scores over the last few years, in fact, and it is clear that this is the greatest batting side in the history of one-day cricket – by a margin.

There have been stumbles in this World Cup, but in the bigger picture, those are outliers. If England have a bad day in the final and New Zealand play their A-game, England might even lose today. But if Captain Morgan’s men play their A-game, they will coast to victory. New Zealand does not have those gears. No other team in the world does – for now.

But one day, they will all have to learn to play like this.

© 2007 IndiaUncut.com. All rights reserved.
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Hello, I am using Encounter 8.1. My mouse is working fine, but my keyboard is not working well in Encounter. I can type in some boxes, but in many boxes I cannot type. The binding key is also not responding. How do I fix this issue? Thanks.

I have completed physical design of a block in innovus. I want to extract rc of that block using quantus .  It will be very helpful if you give step by step procedure and command to run quantus to extract rc of that block.

Hello Everyone,

I was finishing the layout via Innovus and ran verifyConnectivity followed by checkRoute.

verifyConnectivity was okay and it showed no errors and no warnings, whereas checkRoute showed there are 3 unrouted nets.

When i ran the checkRoute command again immediately, it showed no unrouted/unconnected nets.

Which of these commands should we trust or is this really unrouted nets issue?

Looking forward for a response, thanks in advance.

Regards,

Vijay

When I enable clock gating in my synthesis flow (using Genus 18.15), my simulation (using Xcelium) on the post-synthesis netlist fails. The simulation succeeds pre-synthesis and also if I remove clock-gating in the design. I use set_db  lp_insert_clock_gating true to enable clock gating during synthesis. I printed out some of the signals from the netlist and can see where it fails (it incorrectly writes a register). However, I am not sure how to solve this issue or what I should be looking for. Any help would be appreciated. Thanks.

Dear all,

I am using Conformal Constraint Designer (Version 17.1) to analyse a SystemVerilog based design.

While performing default HDL checks it finds  some violations (issues) in RTL and complains (warnings, etc) about RTL checks and others.

My questions:

Is there any directive which I can add to RTL (system Verilog) so that particular line of code or signal is ignored or not checked for HDL or RTL checks.

I can set ignore rules in rule manager (gui) but it does not seems effective if code line number changes or new signals are introduced.

What is the best way to customize default_hdl_rules ?

I will be grateful for your guidance.

Thanks for your time.

Hi,

Is it possible to use a SystemVerilog package which is compiled into a library and then use it in a VHDL-2008 design file? Is such mixed-language flow supported?

I'm considering the latest versions of Incisive / Xcelium available today (Oct 2019).

Thank you,

Michal

It's been a while since you've heard from me...it has been a busy year for sure. One of the reasons I've been so quiet is that I was part of a team working diligently on our latest best kept secret: The MMSIM 12.1.1/MMSIM 13.1 Documentation has...(read more)

Hi Folks, Check out this great new video on YouTube: CDNLive SV 2014: PMC Improves Visibility and Performance with Spectre APS In this video from CDNLive Silicon Valley 2014, Jurgen Hissen, principal engineer, MSCAD, at PMC, discusses an aggressive...(read more)

Hello Spectre Users, Simulating S-parameters in a time domain (transient, periodic steady state) simulator has been and continues to be a challenge for many analog and RF designers. I'm often asked: What is required in order to achieve accurate...(read more)

Hi All, If you were unable to attend IMS 2017 in June 2017, the IMS MicroApp “7 Habits of Highly Successful S-Parameters” is on our Cadence website. On Cadence Online Support , the in-depth AppNote is here: 20466646 . Best regards, Tawna...(read more)

Hello,

I am in a need of a skill program to find all instances of a specific cell (Including Mosaics), throughout the hierarchy. The program should print the instance's name, xy coordinates at the top level, and extract a label name that is dropped on top of it. In case there is no label on top of the found instance, the program should print "No Label Found" in the report text file. This program aims to map PADs cells within top level.

I am using the below Cadence's solution to find instances and it works well. The missing feature is to identify LABELs that are on top of the found instances. 

I tried to use dbGetOverlap() function, within the below code, in few setups but it seems to fail to identify the existence of labels on top of the found instances.

For example: 

overlapLabel=dbGetTrueOverlaps(cv cadr(instBox) list("M1" "text"))

I am interested to add to the Cadence's solution below some code in order to identify labels on top of the found instances.

Any tip would be greatly appreciated.

Thanks,

Danny

--------------------------------------------------------

Inside the scope of isCallable there is code which I don't want to be executed.

The procedure named in isCallable to-day is callable.

I want to make that procedure so it cannot be called.  How do I do that?

I can't change the isCallable line or the scope.  I want to change its behavior by making sure that the procedure does not exist (obviously this would be done before the code is executed).

I have a SKILL script that executes the callback of a menu item, and depends on first redefining an environment variable. 

When a user interrupts the script with ctrl-C, the script cannot finish to set the environment variable back to its default value.

How can I write the script in a way that handles a user interrupt to reset the changed environment variable after the interrupt?

I want to select a constraint, and then run a SKILL command that returns a list with the members of that constraint. Is this possible?

Thx,

I have a modeless informational dialog box defined at the beginning of a SKILL script, but its contents don't display until the script finishes.

How do you get a modeless dialog box contents to display while a SKILL script is running?

procedure(myproc()

   prog((myvars)

     hiDisplayAppDBox()    ; opens blank dialog box - no dboxText contents show until script completes!

     ....rest of SKILL code in script...launches child processes

   );prog

);proc

Can anybody assist with a Skill code /function to disable all callbacks

Hi there,

I'm running a transient simulation, and I want to get all instances with model implementation hisim_hv because after that I want to process the data and to adjust some parameters for this kind of devices before dumping the values.

What is the easiest/fastest way to get those instances in skill/ocean?

What I did until now: 

- save the final OP of the simulation and then in skill

openResults()
selectResults('tranOp)
report(?type "hisim_hv" ?param "vgs")

Output seems to be promising, and looks like I can redirect it to a file and after that I have to parse the file.

Is there other simple way? I mean to not save data to file and to parse it.

Eventually having an instance name, is it possible to get the model implementation (hsim_hv, bsim4, etc..)? 

Best Regards,

Marcel

Here we conclude the blog series and highlight the results of Mediatek 's use of Cadence Perspec™ System Verifier for their SoC level verification. In case you missed it, Part 1 of the blog is here , and Part 2 of the blog is here . One of their key...(read more)

Cadence pulled a fast one at DAC 2018, almost like a bait and switch. We advertised a hands-on workshop to learn about Accellera Portable Stimulus Specification (PSS) v1.0. But we made participants compete head to head, for prizes, and their pride! T...(read more)

Hi all,

I have a question regarding the manufacture : how to check a cluster of same net vias spacing, with have no shape or cline covered

Have you ever manufactured a printed circuit board (PCB) without analyzing all the routed signal traces? Most designers will say “yes, all the time.” Trace widths and spacing are set by constraints,...

[[ Click on the title to access the full blog on the Cadence Community site. ]]

Those who work in the IC Packaging design space have some unique challenges. We bridge between the IC design world (90/45-degree traces with rectangular and octagonal pins) and the PCB domain...

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Did you know that there is a park in San Jose named after a disk drive? Actually, technically it is named after the first computer that used disk drives. You couldn't just go and buy a disk drive...

[[ Click on the title to access the full blog on the Cadence Community site. ]]

Our customers’ tests have become more complex, longer, and consume more resources than before. This increases the need to optimize the regression while not compromising on coverage. Some advanced...

[[ Click on the title to access the full blog on the Cadence Community site. ]]

The Linley Processor Conference always opens with a keynote by Linley Gwenapp giving an overview of processors in whatever is the hottest area. Most of the other presentations during the conference...

[[ Click on the title to access the full blog on the Cadence Community site. ]]

We have talked about aspects of the in-design symbol edit application mode in the past. This is the environment specific to the Allegro® Package Designer Plus layout tools allowing you to work...

[[ Click on the title to access the full blog on the Cadence Community site. ]]

Everyone keeps talking about “the cloud” this and “the cloud” that these days—but you’re a semiconductor designer. Everyone keeps saying “the cloud” is revolutionizing all aspects of electronics design—but what does it mean for you? Cadence's own Tom Hackett discussed this in a presentation at the Cadence Theater during DAC 2019.

What people refer to as “the cloud” is commonly divided into three categories: Infrastructure as a Service (IaaS), Platform as a Service (PaaS), and software as a Service (SaaS). With IaaS, you bring your own software—i.e. loading your owned or appropriately licensed tools onto cloud hardware that you rent by the minute. This service is available from providers like Google Cloud Platform, Amazon Web Service, and Microsoft Azure. In PaaS (also available from the major cloud providers), you create your own offering using capabilities and a software design environment provided by the cloud vendor that makes subsequent scaling and distribution really easy because the service was “born in the cloud”.  Lastly, there’s SaaS, where the cloud is used to access and manage functionality and data without requiring users to set up or manage any of the underlying infrastructure used to provide it.  SaaS companies like Workday and Salesforce deliver their value in this manner.  The Cadence Cloud portfolio makes use of both IaaS and SaaS, depending on the customers’ interest.  Cadence doesn’t have PaaS offerings because our customers don’t create their own EDA software from building blocks that Cadence provides.

All of these designations are great, but you’re a semiconductor designer. Presumably you use Workday or some similar software, or have in the past when you were an intern, but what about all of your tools? Those aren’t on the cloud.

Wait—actually, they are.

Using EDA tools in the cloud allows you to address complexity and data explosion issues you would have to simply struggle through before. Since you don’t have to worry about having the compute-power on-site, you can use way more power than you could before. You may be wary about this new generation of cloud-based tools, but don’t worry: the old rules of cloud computing no longer apply. Cloud capacity is far larger than it used to be, and it’s more secure. Updates to scheduling software means that resource competition isn’t as big of a deal anymore. Clouds today have nearly unlimited capacity—they’re so large that you don’t ever need to worry about running out of space.

The vast increase in raw compute available to designers through the cloud makes something like automotive functional safety verification, previously an extremely long verification task, doable in a reasonable time frame. With the cloud, it’s easy to scale the amount of compute you’re using to fit your task—whether it’s an automotive functional safety-related design or a small one.

Nowadays, the Cadence Cloud Portfolio brings you the best and brightest in cloud technology. No matter what your use case is, the Cadence Cloud Portfolio has a solution that works for you. You can even access the Palladium Cloud, allowing you to try out the benefits of an accelerator without having to buy one.

Cloud computing is the future of EDA. See the future here.

Looking to learn? There's a bunch of new RAKs (Rapid Adoption Kits) available online now!

1) Indago 19.09 Better Driver Tracing and More

Are you new to Indago and not sure where to start? Luckily, there’s a new Rapid Adoption Kit for you: the Indago 19.09 Overview RAK! This neat package contains everything you need to get your debugging started through Indago. In four short labs, plus a brief introductory lab, you’ll have all the basics of Indago 19.09 down—the Indago working environment, the SmartLog, how Indago interacts with the rest of the Cadence Verification Suite, and how Indago uses HDL driver tracing.

Lab 1 discusses the various debugging tools included in Indago and teaches you how to customize your Indago windows and environment settings. Lab 2 covers the SmartLog feature and talks about analyzing and filtering its messages to suit your needs, as well as how to interact with the waveform marker. Lab 3 is an interactive Indago debugging experience—it’ll walk you through how to use Indago and its features in an actual working environment: setting breakpoints, using simulator commands in the Indago console, toolbars, switches, and more. Lab 4 is all things HDL tracing—recording debug data, an introduction to debug assertions, waveform visualizations, driving expression analysis, and single-step driver tracing, among other things.

Interested? Check out the RAK here.

2) IXCOM MSIE: Faster Palladium Build Time

Got several testbenches you want to compile with the same DUT and tests and you want to do it fast? With IXCOM, all you have to do to compile those different testbenches is use the xrun command for each after compiling your DUT. But what exactly is IXCOM, and how does one start using it? This quick RAK can help—here, you’ll learn the basics of using MSIE features with IXCOM, complete with an example to get you started. Using MSIE can vastly improve your build times with Palladium and using IXCOM is the best way to shrink that tedious rebuild time as small as it can get. Check out this RAK here.

3)  JasperGold Control and Status Register Verification App Automates UVM Register Map Verification

New to the JasperGold Control and Status Register (CSR) Verification App for your UVM testbenches? Don’t worry; there’s a RAK for that! This eponymous RAK can get you up and running with this in no time, helping you automate your checks from UVM register map specs. With this RAK, you’ll learn the basics of the JasperGold CSR, how to use JasperGold CSR’s Proof Accelerator, and more. CSR features a model-based approach to predicting a register’s expected value, supports pipeline interfaces, all IP-XACT access policies, and it can fully model any expected register value. It also supports register aliases, read and write semantics, and separate read/write data latencies in any given field.

If this functionality sounds up your alley, you can take a look at this RAK here.

Our customers’ tests have become more complex, longer, and consume more resources than before. This increases the need to optimize the regression while not compromising on coverage.

Some advanced customers of Specman use Machine Learning based solutions to optimize the regressions while some use simpler solutions. Based on a request of an advanced customer, we added a new Coverage API in Specman 19.09 called Coverage Callback. In 20.03, we have further enhanced this API by adding more options. Now there are two Coverage APIs that provide coverage information during the run (the old scan_cover API and this new Callback API). This blog presents these two APIs and compares between them while focusing on the newer one.

Before we get into the specifics of each API, let’s discuss what is common between these APIs and why we need them. Typically, people observe the coverage model after the test ends, and get to know the overall contribution of the test to the coverage. With these two APIs, you can observe the coverage model during the test, and hence, get more insight into the test progress.

Are you wondering about what you can do with this information? Let’s look at some examples.

1. Recognize cases when the test continues to run long after it already reached its coverage goal.
2. View the performance of the coverage curve. If a test is “stuck” at the same grade for a long time, this might indicate that the test is not very good and is just a waste of resource.

These analyses can be performed in the test itself, and then a test can decide to either stop the run, or change something in it configuration, or – post run. You can also present them visually for some analysis, as shown in the blog: Analyze Your Coverage with Python.

scan_cover API (or “Scanning the Coverage Model”)

With this API you can get the current status for any cover group or item you are interested in at any point in time during the test (by calling scan_cover()). It is very simple to use; however it has performance penalty. For getting the coverage grade of any cover group during the test, you should
1. Trigger the scan_cover at any time when you want the coverage model to be scanned.
2. Implement the scan_cover related methods, such as start_item() and end_bucket(). In these methods, you can query the current grade of group/item/bucket.
The blog mentioned earlier: Analyze Your Coverage with Python describes the details and provides an example.

Callback API

The Callback API enables you to get a callback for a desired cover group(s), whenever it is sampled. This API also provides various query methods for getting coverage related information such as what the current sampled value is. So, in essence, it is similar to scan_cover API, but as the phrase says: “same same but different”:

1. Callback API has almost no performance penalty while scan_cover API does.
2. Callback API contains a richer set of query methods that provide a lot of information about the current sampled value (vs just the grade with scan_cover).
3. Using scan_cover API, you decide when you want to query the coverage information (you call scan_cover), while with the Callback API you query the coverage information when the coverage is sampled (from do_callback). So, scan_cover gives you more flexibility, but you do need to find the right timing for this call.

There is no absolute advantage of either of these APIs, this only depends on what you want to do.  

Callback API details

The Callback API is based on a predefined struct called: cover_sampling_callback. In order to use this API, you need to:

1. Define a struct inheriting cover_sampling_callback (cover_cb_save_data below)
   1. Extend the predefined do_callback() method. This method is a hook being called whenever any of the cover groups that are registered to the cover_sampling_callback instance is being sampled.
   2. From do_callback() you can access coverage data by using queries such as: is_currently_per_type(), get_current_group_grade() and get_current_cover_group() (as in the example below) and many more such as: get_relevant_group_layers() and get_simple_cross_sampled_bucket_name().
2. Register the desired cover group(s) to this struct instance using the register() method.

Take a look at the following code:

// Define a coverage callback.
// Its behavior – print to screen the current grade.
struct cover_cb_save_data like cover_sampling_callback {
    do_callback() is only {
       // In this example, we care only about the per_type grade, and not per_instance
       if is_currently_per_type() {           
            var cur_grade : real = get_current_group_grade();
            sys.save_data (get_current_cover_group().get_name(), cur_grade);
        };//if
    };//do_callback()
};// cover_cb_send_data


extend sys {
    !cb : cover_cb_save_data;

   // Instantiate the coverage callback, and register to it two of my coverage groups
    run() is also {
       cb  = new  with {
        var gr1:=rf_manager.get_struct_by_name("packet").get_cover_group("packet_cover");
        .register(gr1);
        var gr2:=rf_manager.get_struct_by_name("sys").get_cover_group("mem_cover");
       .register(gr2);
       };//new  
    };//run()

  save_data(group_name : string, group_grade : real) is {
        //here you either print the values to the screen, update a graph you show or save to a db 
  };// save_data
};//sys

In the blog Analyze Your Coverage with Python mentioned above, we show an example of how you can use the scan_cover API to extract coverage information during the run, and then use the Specman-Python API to display the coverage interactively during the run (using plotting Python library - matplotlib). If you find this usage interesting and you want to use the same example, by the Callback API instead of the scan_cover API, you can download the full example from GIT from here: https://github.com/efratcdn/cover_callback.

Specman Team

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