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Observations from Uppsala Computer Simulation, Virtual Platforms, Embedded Programming, Multicore and More (by Jakob Engblom)

Wind River Blog: Simics 4.8 is Here

2013 May 21 19:05 / Leave a Comment / Jakob

Simics 4.8 is finally released, and I put up a blog post explaining the most important news in this release. It is two years since we released Simics 4.6, so there is quite a bit of news in Simics 4.8 – even though lots of functionality has been released continuously into 4.6 over the past twenty four months. My personal favorite are the comments you can put on an execution and the stop log,  but then again, that might be because they have been a couple of pet ideas of mine so I am hardly an impartial judge. Everything else is also really good, and the engineering teams and marketing teams involved have put in a lot of effort into this release (as we do in all releases).

 

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Posted in: virtual platforms, Wind River Blog / Tagged: 4.8, Simics

A Few Electrons too Many

2013 May 9 22:16 / 2 Comments / Jakob

Adding electronics to systems that used to be mechanical has been the great wave of innovation for a quite a while now. Modern transportation just would not work without all the electronics and computers inside (someone once quipped that a modern fighter is just a plastic airplane full of software), and so much convenience has been provided by automation and smarts driven by electronics. However, this also introduces brand new ways that things can break, and sometimes I wonder if we really are not setting ourselves up for major problems when the electrons stop flowing.

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Posted in: embedded systeme, trains, transportation

Wind River Blog: Visuality NQ CIFS Server on Simics

2013 April 23 11:05 / Leave a Comment / Jakob

There is a new post at my Wind River blog, about how I ran a Windows file share server (CIFS) on a Simics-simulated VxWorks big-endian Power Architecture target. Something that just should work, given that the software in question is known to work in the real world. But still, pretty cool, and a bit eerie.

 

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Posted in: virtual platforms, Wind River Blog / Tagged: Simics, Visuality NQ, Windows

Everything in the Cloud?

2013 March 30 21:12 / 6 Comments / Jakob

Cloud… I tend to dislike hype and I am honestly quite sick of all the talk about cloud computing and “anything as a service”. Still, it is an intriguing area. Last week, I attended Produktledardagen, a very inspiring product management and product leadership seminar, innovation lab, and social event for the profession of product management.  A significant part of the discussion was about the Cloud, and how to think about it from a product perspective.  Suddenly, with this perspective, it actually got quite interesting. In particular, trying to define to myself just what a cloud service is.

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Posted in: business issues, off-topic / Tagged: Cloud, cloud computing, hype, salesforce, Waze

Wind River Blog: TCF and Simics

2013 March 26 11:00 / Leave a Comment / Jakob

On my Wind River blog, you can now find a description on how we have used the Eclipse TCF (target connection framework) to build the Simics GUI. Or rather, the connection between the Simics GUI and the Simics simulation process. It is actually quite revolutionary what you can do with the TCF, compared to older debug protocols. In particular, TCF lets you combine many different services across a single connection.

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Posted in: virtual platforms, Wind River Blog / Tagged: debugging, reverse debugging, Simics, TCF

Off-Topic: Moving Bad Piggies Save Games

2013 March 15 23:00 / 1 Comment / Jakob

I am really a great fan of the Rovio games from Angry Birds and on. One of these games is the tricky puzzler Bad Piggies, which I have spent a great deal of time playing to unlock new levels (and as an illustration of deterministic simulation). Playing on my Nexus 7 I have solved level after level… and then I got myself a new Xperia phone. Not that playing on the go is that big an attraction, but if I happened to want to do that, starting over just felt wrong.

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Posted in: computer games / Tagged: Android, Bad Piggies, iOS, Nexus, Rovio, save games, Xperia

Two Cores, Four Cores, Eight Cores – Mobile Variety

2013 March 3 22:26 / Leave a Comment / Jakob

Probably thanks to the yearly Mobile World Congress, there have been a slew of recent announcements of mobile application processors recently. Everything is ARM-based, but show quite some variety in the CPU core configurations used. Indeed, I think this variety has something to say on the general state of multicore.

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Posted in: computer architecture, multicore computer architecture, multicore software / Tagged: ARM, bigLITTLE, Cortex-A15, Cortex-A7, Cortex-A9, eQuad, mobile, MP6530, Renesas, ST Ericsson

Bliss: Failing to Pivot for Ideology

2013 February 17 22:05 / Leave a Comment / Jakob

Note: This post was caused by listening to an interesting science podcast while thinking about the theories of startups, and the connection might seem a bit odd. Still, I think there is something to be learnt here. End note.

I recently listened to the episode on Bliss, by the Radiolab podcast. As always, Radiolab manages to take a theme and connect all kinds of things to it. In this case, bliss as in happiness turned into Bliss, the man, and his invention of Symbolics. Symbolics was an attempt to create a rational language based on symbols that would not allow the manipulation of human opinion or feeling like regular languages do. It was an attempt to create an antidote to the manipulations of dictators, tricksters, and populists (Bliss himself had been briefly interned in a pre-war German concentration camp, so he definitely knew what words could do). He designed a symbolic writing scheme that was intended to only communicate ideas clearly and unambiguously and with no room for demagogery and oratory. In the end, nobody wanted to use the language for its original purpose.

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Posted in: business issues, general history, general research, history / Tagged: Blissymbolics, Charles Bliss, pivot, startup

Wind River Blog and Movie: Demo of Simics Debugging

2013 January 9 22:40 / 5 Comments / Jakob

Last year, I did a Simics webinar which included a two-part demo of how to use Simics to debug an endianness bug in a networked system as it migrates from big-endian to a little-endian system. Along the way, I also showed off various Simics features like reverse execution and checkpointing and scripted execution.

The demo is now online at the Wind River Youtube channel, and the setup is explained in a blog post at the Wind River company blog which is worth reading before watching the video.

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Posted in: programming, virtual platforms, Wind River Blog / Tagged: debugging, demo, endianness, networking, reverse debugging, Simics, video

Simulation vs Reality in Schlock Mercenary

2013 January 7 11:25 / Leave a Comment / Jakob

Schlock Mercenary is a very funny web (and print) comic that I discovered earlier this year via a list at ArsTechnica. In reading up on back issues and back stories, I came across a nice little gem about simulation.

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Posted in: computer simulation technology, funny

Programming like Lego

2013 January 6 22:58 / Leave a Comment / Jakob

LEGOs seem to be a favorite analogy for people bemoaning the state of software development today. “If only it would be as simple as putting Legos together” is a common enough statement, along with various proposals to make software that is Lego-like. Sometime, I wonder if people making these statements have actually tried to build anything non-trivial from Lego recently. Here, I will look a bit closer at the Lego-programming analogy. There is indeed quite a lot to it, but it is not all about child-level simplicity. I think there are some good lessons that can be learnt from analogizing Lego and programming.

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Posted in: programming / Tagged: lego

Does ISA Matter for Performance?

2012 December 23 22:54 / 6 Comments / Jakob

When I grew up with computers, the big RISC vs CISC debate was raging. At the time, in the late 1980s, it did indeed seem that RISC was inherently superior to CISC. SPARCs, MIPS, and Alpha all outpaced boring old x86, VAX and 68000 processors. This turned out to be a historical parenthesis, as the Pentium Pro from Intel showed how RISC-style performance could be mated to a CISC ISA. However, maybe ISAs still do matter.

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Posted in: computer architecture / Tagged: 32-bit, 64-bit, 68000, ARM, CISC, instruction set architecture, Intel, ISA, MIPS, performance optimization, power architecture, RISC, SPARC, x86

Wind River Blog: Debugging Simics using Simics

2012 December 6 13:04 / 2 Comments / Jakob

There is a new post at my Wind River blog, telling the story of how some of the Simics developers used Simics itself to debug an intermittent Simics program crash caused by a timing-sensitive race condition.

Running Simics on itself is pretty cool, and shows the power of the simulator and its applicability even to really complex software.

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Posted in: multicore debug, programming, virtual platforms / Tagged: Debug, race condition, reverse debugging, Simics

Wind River Blog: Simics and Flying Piggies

2012 November 28 11:59 / Leave a Comment / Jakob

I just added a new blog post at the Wind River blog, about determinism and illustrating Simics-style determinism is by looking at the game Bad Piggies. Games and simulators have quite a lot in common, actually.

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Posted in: computer games, off-topic, virtual machines, Wind River Blog / Tagged: Bad Piggies, determinism, Rovio, Simics, variability

Dragons can be Useful – when AT Models Make Sense

2012 November 12 15:51 / 4 Comments / Jakob

Carbon Design Systems keeps putting out interesting blog posts at a good pace. Bill Neifert at recently put up a blog post about the various of speed/accuracy tradeoffs you can make when building virtual platforms. The main message of the blog is that you should use a mix of fast models (TLM + JIT, like the ARM Fast Models) and cycle-accurate generated-from-RTL models (like the models generated by Carbon’s tools). By switching between the levels of abstraction when you need to go fast or go deep, you get something that is pretty much the best of both worlds (I already blogged about the change between abstraction before). It makes perfect sense, and I am all with him. There are dragons in the middle land.

However, I do not quite agree with Bill about the absolute uselessness of the intermediate types of models, like SystemC TLM-2.0 AT.  Basically, what is traditionally called “cycle accurate modeling” (while not derived from RTL).

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Posted in: computer simulation technology, virtual platforms / Tagged: Bill Neifert, Carbon, clock-cycle models, cycle accuracy, dragons

Logging (Some More Thoughts)

2012 October 28 23:38 / 1 Comment / Jakob

Logging as as debug method is not new, and I have been writing about it to and from over the past few years myself.  At the S4D conference, tracing and logging keeps coming up as a topic (see my reports from 2009, 2010  and 2012 ).  I recently found an interesting piece on logging from the IT world in the ACM Queue (“Advances and Challenges in Log Analysis“, Adam Oliner, ACM Queue December 2011).  Here, I want to address some of my current thoughts on the topic.

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Posted in: embedded software, embedded systeme, programming / Tagged: ACM Queue, Adam Oliner, debugging, logging, tracing

Reverse Execution History Updates

2012 September 29 21:33 / Leave a Comment / Jakob

After some discussions at the S4D conference last week, I have some additional updates to the history and technologies of reverse execution. I have found one new commercial product at a much earlier point in time, and an interesting note on memory consistency.

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Posted in: embedded systeme, history of computing, programming / Tagged: CTS, Lauterbach, reverse debugging, reverse execution

Wind River Blog: Exposing OS Kernel Races with Landslide

2012 September 26 21:18 / Leave a Comment / Jakob

There is a new blog post on my Wind River blog, about the Landslide system from CMU. It is a pretty impressive Master’s Thesis project that used the control that Simics has over interrupts to systematically try different OS kernel thread interleavings to find concurrency bugs. The blog is an interview with Ben Blum, the student who did the work. Ben is now a PhD student, and I bet that he will continue to generate cool stuff in the future.

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Posted in: parallel computing, programming, Wind River Blog / Tagged: Ben Blum, debugging, Landslide, operating systems, Simics

S4D 2012 – Notes

2012 September 24 22:11 / 2 Comments / Jakob

Last week, I attended my fourth System, Software, SoC and Silicon Degug conference (S4D) in a row. I think the silicon part is getting less attention these days, most of the papers were on how to debug software. Often with the help of hardware, and with an angle to how software runs in SoCs and systems. I presented a paper reviewing the technology and history of reverse debugging, which went down pretty well.

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Posted in: appearances, articles, conferences, EDA, embedded software, embedded systeme / Tagged: debugging, Hardware debug support, S4D, software

SiCS Multicore Day 2012

2012 September 16 22:12 / 4 Comments / Jakob

The 2012 edition of the SiCS Multicore Day was fun, like they have always been in the past. I missed it in 2010 and 2011, but could make it back this year. It was interesting to see that the points where keynote speakers disagreed was similar to previous years, albeit with some new twists. There was also a trend in architecture, moving crypto operations into the core processor ISA, that indicates another angle on the hardware accelerator space.

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Posted in: computer architecture, conferences, embedded software, multicore computer architecture, multicore debug, multicore software, parallel computing, programming / Tagged: Erik Hagersten, heterogeneous, homogeneous, James Larus, Rich Hetherington, SiCS Multicore days, Stephen Hill

Paper & Talk at S4D 2012: Reverse Debug

2012 September 10 11:03 / Leave a Comment / Jakob

I am going to the S4D conference for the third year in a row. This year, I have a paper on reverse debugging, reviewing the technology, products, and history of the idea. I will probably write a longer blog post after the conference, interesting things tend to come up.

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Posted in: appearances, articles, conferences, embedded systeme, programming / Tagged: reverse debugging, reverse execution, S4D

Negative Results

2012 September 2 20:48 / 1 Comment / Jakob

In the past year, I have started listening to various podcast from the “Skeptic” community. Although much of the discussion tends to center on medicine (because of the sadly enormous market for quackery) and natural science (because the sad fight over evolution), it has made me think and reflect more about the nature of science and publishing. Indeed, it would have been great if this kind of material would have been easily found back when I was doing my PhD.

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Posted in: general research, programming / Tagged: Chris French, Ed Yong, rant, science, scientific method, skepticism

Speaking at Embedded Conference Scandinavia

2012 August 29 12:58 / Leave a Comment / Jakob

I am going to be talking about how to transport bugs with virtual platform checkpoints, in the Software Tools track at the Embedded Conference Scandinavia, on October 3, 2012, in Stockholm (Sweden). The ECS is a nice event, and there are several tracks to choose from both on October 2 and October 3. In addition to the tracks, Jan Bosch from Chalmers is going to present a keynote that I am sure will be very entertaining (see my notes from a presentation he did in Göteborg last year).

 

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Posted in: appearances, embedded software, embedded systeme, programming, virtual platforms / Tagged: bug, bug transportation, debugging, Simics

Wind River Blog: Testing Multicore Scaling with a Simics QSP

2012 August 27 21:39 / Leave a Comment / Jakob

A few years ago, I built a demo on Simics that used a hacked Freescale MPC8641D target that was forced to scale from 1 to 8 cores. Some interesting experiements could be made using this target, and it was nicely scalable for its time. However, I always wanted to have something just a bit bigger. Say 20 cores, or 100. Just to see what would happen. Finally, I got it.

The Simics QSP target that we quietly launched earlier this Summer is such a scalable target. As discussed in a blog post describing the architecture, it is designed to scale to 128 cores currently. Using this ability, I repeated my old experiments, but trying very large threads counts and target core counts. The results show clearly that the way that I coded my parallel computation program was pretty bad, and I really would like to try to rewrite it using some more modern threading library. All I need is time and a way to cross-compile Wool…

Anyway, the new blog post is here.

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Posted in: multicore software, virtual machines, Wind River Blog / Tagged: multicore, QSP, Simics

Speaking at SiCS Multicore Day 2012

2012 August 16 11:43 / Leave a Comment / Jakob

I am scheduled to talk at the SiCS multicore day 2012 (like I did back in 2009 and 2008). The event takes palce on September 13, at SiCS in Kista. My topic will be on System-Level Debug – how we can make debuggers that work for big systems.

This year, the multicore day is part of a bigger Software Week event, which also covers cloud and internet of things. See you there!

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Posted in: appearances, embedded systeme, programming / Tagged: debugging, SiCS Multicore days, system-level debug

Buying High Technology

2012 August 8 02:19 / 1 Comment / Jakob

Selling and marketing high technology is what I do for a living. My counterpart is the customer or buyer, and I help design, build, explain, an market these products.  In this role, I am most usually the expert on the domain, helping potential customers understand what we sell and why it will help them.  Both at the high-level value proposition and the details behind it.  Some people focus most of the their energy on the high-level value proposition, but I feel that youoften need a bit detail backing that as well.

I recently had the enlightening experience of being on the buying side instead, experiencing the transition from high-level value proposition to low-level details.  It struck me as being quite similar to what the customers for our virtual platforms would experience when coming in new to the field.

I bought a camera.

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Posted in: business issues, gadgets / Tagged: camera, Canon, lens, marketing, Nikon, Pentax, sales, Sony

“Eagle” Cycle-Accurate Simulator Anno 1979

2012 July 21 20:40 / 1 Comment / Jakob

I recently read the classic book The Soul of a New Machine by Tracy Kidder. Even though it describes the project to build a machine that was launched more than 30 years ago, the story is still fresh and familiar. Corporate intrigue, managing difficult people, clever engineering, high pressure, all familiar ingredients in computing today just as it was back then. With my interesting in computer history and simulation, I was delighted to actually find a simulator in the story too! It was a cycle-accurate simulator of the design, programmed in 1979.

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Posted in: computer architecture, computer simulation technology, history of computing, virtual platforms / Tagged: 32-bit, cycle accuracy, Data General, Eclipse MV/8000, Soul of a new Machine, Tracy Kidder

Some Fun Cache Results from Carbon

2012 July 6 20:40 / 2 Comments / Jakob

Carbon Design Systems have been on a veritable blogging spree recently, pushing out a large number of posts around various topics. Maybe a bit brief for my taste in most cases (I have a tendency to throw out 1000+ word pseudo-articles when I take the time to write a blog), but sometimes very interesting nevertheless. I particularly liked a few posts on cache analysis, as they presented some good insight into not-quite-expected processor and cache behaviors.

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Posted in: computer architecture, computer simulation technology, EDA, ESL / Tagged: cache, Carbon, cycle accuracy, performance optimization

Wind River Blog: Inside the Simics QSP – Additional Notes

2012 July 6 20:11 / Leave a Comment / Jakob

There is a new post at my Wind River blog, about the design and technical contents of the new Simics Quick Start Platforms, more widely known as the QSP. The blog describes the virtual-only hardware that forms part of the QSP, and how it was designed. It is interesting to note that the hardware ended up a bit more complex that I initially thought it would be, since an ideal virtual platform should be very simple. Right? Turns out an OS complicates things.

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Posted in: virtual machines, Wind River Blog / Tagged: Android, Carbon, CPAK, QSP, Simics

Off-topic: Society without God

2012 July 2 22:06 / 1 Comment / Jakob

I just finished reading Society without God, by American sociologist Phil Zuckerman. The book came out back in 2008, but I heard about it recently on a skeptic podcast and I felt I just had to buy it. Phil Zuckerman spent a year in Denmark in 2006, and also visited Sweden during that time to perform interviews with a wide sample of what seems to me to be typical Swedes and Danes, trying to understand their attitude towards god and religion. His conclusion is that the Nordic countries today are a special little area of deep secularism in a world that is mostly religious and apparently growing more religious recently. Even in fairly secularized Western Europe, the Nordic countries stand out (or at least Denmark and Sweden does, in his research). So what? For a Swede like myself this is pretty obvious… but when you combine this with the fact that the standard of living and overall feeling of security and quality of life in Denmark and Sweden is very high, Zuckerman finds a great argument against a certain argument brought forth by Christian conservatives in the US…

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Posted in: books, off-topic, Politics, popular culture / Tagged: book review, Denmark, Phil Zuckerman, Sweden

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Recent Posts

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  • A Few Electrons too Many
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  • Off-Topic: Moving Bad Piggies Save Games
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  • Simulation vs Reality in Schlock Mercenary
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