A long time ago, when I was a PhD student at Uppsala University, I supervised a few Master’s students at the company CC-Systems, in some topics related to the simulation of real-time distributed computer systems for the purpose of software testing. One of the students, Magnus Nilsson, worked on a concept called “Time-Accurate Simulation”, where we annotated the source code of a program with the time it would take to execute (roughly) on the its eventual hardware platform. It was a workable idea at the time that we used for the simulation of distributed CAN systems. So, I was surprised and intrigued when I saw the same idea pop up in a paper written last year – only taken to the next level (or two) and used for detailed hardware design!
Continue reading “Time-Accurate Simulation Revisited – 15 years later”
Intel is a big Simics user, but most of the time Intel internal use of Simics is kept internal. However, we recently had the chance to interview Karthik Kumar and Thomas Willhalm of Intel about how they used Simics to interact with external companies and improve Intel hardware designs. The interview is found on the Wind River blog network.
It is also my last blog post written at Wind River; since January 18, I am working at Intel. I am working on ways to keep publishing texts about Simics and simulation, but the details are not yet clear.
I just posted a short blog post on the Wind River blog, introducing a video demo of the Web API to Wind River Helix Lab Cloud. In the post and video, I show how the Lab Cloud Web API works. For someone familiar with REST-style APIs, this is probably baby-level, but for me and probably most of our user base, it is something new and a rather interesting style for an API. Thus, doing a video that shows the first few steps of authentication and getting things going seems like a good idea.
On November 3, 2015, I will give a presentation at the Embedded Conference Scandinavia about simulating IoT systems. The conference program can be found at http://www.svenskelektronik.se/ECS/ECS15/Program.html, with my session detailed at http://www.svenskelektronik.se/ECS/ECS15/Program/IoT%20Development.html.
My topic is how to realistically simulate very large IoT networks for software testing and system development. This is a fun field where I have spent significant time recently. Only a couple of weeks ago, I tried my hand simulating a 1000-node network. Which worked! I had 1000 ARM-based nodes running VxWorks running at the same time, inside a single Simics process, and at speeds close to real time! It did use some 55GB of RAM, which I think is a personal record for largest use of system resources from a single process. Still, it only took a dozen processors to do it.
There is a new post at my Wind River blog, about the new Wind River Helix Lab Cloud product that we launched for real last week. The Lab Cloud is a really cool way to expose Simics-style functionality, and my blog goes through some of the more prominent use cases for a simulator in the cloud. There a couple of demo videos linked from the blog, and I have also set up a Youtube playlist collecting the Simics demos and other videos that we have posted there. Quite a set over the past few years, actually!
There is a new post at my Wind River blog, about how I helped a colleague resolve a real problem using the preview version of the new Helix Lab Cloud system. The Lab Cloud right now is basically Simics behind a simplified web user interface, exposing the checkpointing and record-replay facilities in a very clear way. You can also share your sessions for live interactions with other people, which is truly cool.
I just added a new blog post on the Wind River blog, about how you do fault injection with Simics. This blog post covers the new fault injection framework we added in Simics 5, and the interesting things you can do when you add record and replay capabilities to spontaneous interactive work with Simics. There is also a Youtube demo video of the system in action.
While I was on vacation, Wind River published a blog post I wrote about the new multicore accelerator feature of Simics 5. The post has some details on what we did, and some of the things we learnt about simulation performance.
I have read a few news items and blog posts recently about how various types of software running on top of virtual machines and emulators have managed to either break the emulators or at least detect their presence and self-destruct. This is a fascinating topic, as it touches on the deep principles of computing: just because a piece of software can be Turing-equivalent to a piece of hardware does not mean that software that goes looking for the differences won’t find any or won’t be able to behave differently on a simulator and on the real thing.
Continue reading “Breaking and Detecting Simulators and Emulators”
There is a new post at my Wind River blog, about the Trinity of Simulation – the computer, the system, and the world. It discusses how you build a really complete system model using not just a virtual platform like Simics, but you also integrate it with a model of the system the computer sits in, as well as the world around it. Like this:
Read more about it in the blog post, and all the older blog posts it links to!
Last year, I concluded a programming project at work that clearly demonstrated that real programming tasks tend to involve multiple languages. I once made a remark to a journalist that there is a zoo of languages inside all real products, and my little project provided a very clear example of this. The project, as discussed previously, was to build an automated integration between a simple Simics target system and the Simulink processor-in-the-loop code testing system. In the course of this project, I used six or seven languages (depending on how you count), three C compilers, and three tools. Eight different compilers were involved in total.
Continue reading “Single Programming Language? No Way! (For Real Work)”
There is a new post at my Wind River blog, an interview with Andreas Buchwieser from the Wind River office in München. It discusses how Simics can be applied to the field of safety-critical systems, including helping test the software to get it certified. Really interesting, and in particular it is worth noting that qualifying tools in the IEC 61508 and ISO 26262 context is much easier than in DO-178B/C. The industrial family of safety standards have been created to allow for tools to help validate an application without forcing incredibly high demands on the development of those tools.
There is a new post at my Wind River blog, about how Simics is used to simulate large wireless networks for IoT (Internet-of-Things) applications.
It is funny for me to be back at the IoT game. A decade ago (time flies, doesn’t it?), at Virtutech, I and Johan Runeson took part in an EU research project on exactly this topic. Unfortunately, we had to back out of that project due to economic circumstances and failing management commitment, but we still learnt a few things that were relevant now that we are back in the IoT game. In particular, how to simulate wireless networks in a reasonable way in a transaction-level simulator. Thus, payback for the investment took 10 years to arrive, but it did arrive. To me, that underscores the need to be a bit speculative, take some risk, and try to explore the future.
I am going to be speaking at the 2015 Embedded World Conference in Nürnberg, Germany. My talk is about Continuous Integration for embedded systems, and in particular how to enable it using simulation technology such as Simics.
My talk is at 16.00 to 16.30, in session 03/II, Software Quality I – Design & Verification Methods.
There is a new post at my Wind River blog, about how you can use Simics to enable the automatic testing of pretty much any computer system (as long as we can put it inside a simulator). This is a natural follow-up to the earlier post about continuous integration with Simics and Simics-Simulink integrations — automated test runs is a mandatory and necessary part of all modern software development.
At the Wind River corporate blog, there is a blog post that I wrote about continuous integration and Simics. At the Elsevier Computer Science Connect blog, there is also a blog post about continuous integration and Simics that I wrote. These two texts are essentially the same, and I had the good fortune to get it posted in multiple places. The reason it is up at Elsevier is to help promote our soon-to-be-released book at about virtual platforms and simulation (and a little bit about Simics), and hopefully we will reach a larger audience with both messages: CI with Simics is a great idea, and the book is a great book to buy.
During my vacation, a blog post went up on the Wind River blog with an interview with Hyungmin Cho, a researcher at Stanford. Hyungmin has done some seriously heavy and cool work with Simics, using it together with a circuit-level simulator to investigate error resiliency in hardware devices, and how errors propagate from hardware into the software. As part of this process, he has setup an automated test system using Simics, and this system has done more than a million automated Simics runs. That is an insane number – I have been using Simics for twelve years now, and if I had used it every day for all these years, I would have had to start 10 runs per hour, every hour of the day. It shows the power of automation along with parallel runs on clusters of machines – once the setup is automated, you can pour on the volume.
Continue reading “Wind River Blog: A Million Simics Runs (and lots of cool technology)”
For the past six months I have not been doing much blogging at all, neither here nor on the Wind River blog. The reason is that I have been directing my writing energy into writing a text book about Simics together with Daniel Aarno at Intel. Last year, Daniel and I worked on an Intel Technology Journal issue on Simics. The ITJ issue was kind of a first step on the way to the book, collecting several articles about Simics usage at Intel and elsewhere. The book itself will be much more of a detailed description of Simics and how it works and why it works the way it works.
Continue reading “Busy Writing a Book About Simics”
The September 2013 issue of the Intel Technology Journal (which actually arrived in December) is all about Simics. Daniel Aarno of Intel and I served as the content architects for the issue, which meant that we managed to contributed articles from various sources, and wrote an introductory article about Simics and its usage in general. It has taken a while to get this journal issue out, and now that it is done it feels just great! I am very happy about the quality of all the ten contributed articles, and reading the final versions of them actually taught me some new things you could do with Simics! I already wrote about the issue in a Wind River blog post, so in this my personal blog I want to be a little bit more, well, personal.
Continue reading “Intel Technology Journal on Simics”
On the Wind River blog network, I have a short posting about network simulation with Simics. It points to the network demo video that we put up on Youtube a few weeks ago, along with some explanations of what is shown in the video. In short, we show a simple example of a network being simulated in Simics, along with some examples of what you can do with it.
As an old embedded systems and real-time guy, I have always worked with computer systems that are in some way tied to their environment. Simics has often been used to model such computer systems, inside of customer organizations. Which makes it a bit hard to show… however, recently I have cooked up a demo showing Simics simulating a computer system alongside a physical system.
I just put out a post on the Wind River blog, pointing to both a video of my own “water heater” demo and some other Youtube videos showing Simics integrated with simulations of the real world. A screenshot of my setup in action is shown on the side of this post.
There is a new post at my Wind River blog, featuring a recently-posted video demo of device and systems modeling with Simics. In this video demo, we show an outline of the modeling flow used with Simics 4.8, using only the Eclipse interface. It is actually quite new that we can do this much modeling from within Eclipse; recent efforts in improving the Simics user experience are starting to pay off. As part of the product design team, it feels good to see how even quite small features can really improve the usability of the product.
It is also my first blog post on the recently renovated Wind River blog network. I like the new look of the corporate blog, even if I will have to go back and adjust some older blog images to account for the change from a dark to a light background.
There is a new post at my Wind River blog, where I go back to the basics of reverse execution in Simics and what it can do. The post is not about reverse debugging, about which I have written quite a bit (see for example my series of blog posts: 1, 2, 3, 4, 5, 6), but about the core of reverse execution. I.e., moving the system state back in time in a variety of ways. There is an accompanying video demo on Youtube.
There is a new post at my Wind River blog, about how some new features in Simics 4.8 improve the collaboration power of Simics checkpoints. For the first time, Simics checkpoint can now carry a piece of history (slice of time), which also makes reverse execution and reverse debug work with checkpoints in a logical way.
Continue reading “Wind River Blog: Collaborating with Recording Checkpoints”
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).
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.
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.
Continue reading “Wind River Blog: TCF and Simics”
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.
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.
Continue reading “Simulation vs Reality in Schlock Mercenary”