There are still some articles being published that I wrote while at Wind River. The latest is a piece on just what you could do with a lab in cloud – in particular, a lab based on virtual platforms like Simics. Eva Skoglund at Wind River and I wrote this together, and it is a nice high-level summary of why you really need to have a virtual cloud-based lab if you are doing embedded systems development. It is published in the online European magazine Electropages.
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.
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.
I just read a quite interesting article by Christian Pinto et al, “GPGPU-Accelerated Parallel and Fast Simulation of Thousand-core Platforms“, published at the CCGRID 2011 conference. It discusses some work in using a GPGPU to run simulations of massively parallel computers, using the parallelism of the GPU to speed the simulation. Intriguing concept, but the execution is not without its flaws and it is unclear at least from the paper just how well this generalizes, scales, or compares to parallel simulation on a general-purpose multicore machine.
I just had two articles published the Embedded Design part of the EETimes.
First, “Rethink your project planning with a virtual platform“, which talks about how virtual platforms can change your entire project planning. Essentially, by reducing project friction and risks related to hardware availability, software integration, and show-stopper bugs, you can make projects work much better.
Then we have “Transporting bugs with virtual checkpoints“, which is a shorter, popular science, version of the paper I published last year at S4D. This describes how you can use checkpointing in a virtual platform to communicate bugs across time, space, and teams.
This post features some additional notes on the topic of transporting bugs with checkpoints, which is the subject of a paper at the S4D 2010 conference.
The idea of transporting bugs with checkpoints is some ways obvious. If you have a checkpoint of a state, of course you move it. Right? However, changing how you think about reporting bugs takes time. There are also some practical issues to be resolved. The S4D paper goes into some of the aspects of making checkpointing practical.
One of the many nice effects of the Wind River acquisition of Simics is that I will be blogging as part of the Wind River Blog network. My first post there is up now, and it is a short (at least compared to a textbook, I admit it looks terribly long for a blog post) overview of how Simics works inside.
I think it is important for users of technologically advanced tools to know a bit of how they work. A classic example of this is compilers, where I taught an ESC class almost a decade ago which is my most popular piece of writing to date…
The paper will explain how we did Simics-style checkpointing in SystemC, using the GreenSocs GreenConfig mechanisms to obtain an approximation for the Simics attribute system.
I have a short article on multicore systems development and virtual platforms in the May 2009 issue of ECN magazine, over at www.ecnmag.com.
Another Cadence guest blog entry, about the overall impact of virtual platforms on the interaction between hardware and software designers. Essentially, virtual platforms are a great tool to make software and hardware people talk to each other more, since it provides a common basis for understanding.
Virtutech and Cadence yesterday announced the integration of Virtutech Simics and Cadence ISX (Incisive Software Extensions), which is essentially a directed random test framework for software. With this tool integration, you can systematically test low-level software and the hardware-software (device driver) interface of a system, leveraging a virtual platform.
I have an article about ecosystem enablement for new hardware, co-authored with Richard Schnur of Freescale published in the December 2008 issue of EDA Tech Forum. The core concept is that a virtual platform solution makes it possible to get a new chip to market faster with better software support, and even enables virtual design-in of a chip at OEM customers before hardware becomes available. The article builds on our joint experience with the QorIQ P4080 launch in the Summer of 2008, where we had several operating systems and middleware packages in place at the moment the chip was announced. EDA Tech Forum requires registration, but it was still free, and there are many other good articles available.
Embedded.com just listed the ten most visited articles on their website during 2008, and my contribution on debugging multiprocessor code was number ten. If you want some more meat around multiprocessor debug, please peruse the various papers and presentations found on my personal website.
I have an article appearing in the latest issue of Elektronik i Norden, about using virtual platforms for multicore computer systems. It is framed in the context of the Freescale multicore push, in particular the QorIQ P4080, and addresses the common issues of debug, execution speed, and the need to zoom in on details every once in a while.
Chip Design Magazine published an article by me in their August/September 2008, about Getting Software into the Hardware Design Loop. The article is about the technical and marketing aspects of how chip designers can get early feedback from software and systems designers, early in the hardware design process. The vehicle for this? Virtual platforms, obviously.
The article/editoral “Using virtual platforms to improve AdvancedTCA software development practice” is now up at CompactPCI and AdvancedTCA Systems, an online and paper journal for the rack-based market. It is about our experience at Virtutech in using virtual platforms to drive system and software development for “pretty large” target systems, even those based on standard hardware.
And really, there is no such thing as a standard embedded system. Even if you use a standard backplane and buy off-the-shelf boards and cards to put in it, the combination of cards and added mezzanine cards makes each system quite unique. If you could use completely standard PC hardware for your system with no custom additions or special IO units, the thing would in likelihood not actually be an embedded system.
I have another short technical piece published about Multicore Debug at the EETimes (and their network of related publications, like Embedded.com). Pretty short piece, and they cut out some bits to make it fit their format. Nothing new to fans of virtual platforms for software development, basically we can use virtual platforms to reintroduce control over parallel and for all practical purposes chaotic hardware/software systems.
I have another opinion piece published over at SCDsource.com. The title, “Why virtual platforms need cycle-accurate models“, was their creation, not mine, and I think it is a little bit off the main message of the piece.The follow-up discussion is also fairly interesting.
The key thing that I want to get across is that we need virtual platforms where we can spend most of our time executing in a fast, not-very-detailed mode to get the software somewhere interesting. Once we get to the interesting spot, we can then switch to more detailed models to get detailed information about the software behavior and especially its low-level timing. Getting to that point in detailed mode is impossible since it would take too much time.
This is something that computer architecture researchers have been doing for a very long time, just look at how toolsets like SimpleScalar and Simics with the Wisconsin GEMS system use fast mode for “positioning” and more detailed execution for “measurement”. It is also what is now commercial with the Simics Freescale QorIQ P4080 Hybrid virtual platform. Tensilica also have the ability to switch mode in their toolchain.
See an upcoming post for more on how to get at the cycle-accurate models – this was just to point out that that the article is there, for symmetry with previous posts about my articles popping up in places.
I just got another article published! In the April 2008 issue of the ACM Transactions on Embedded Computing Systems (TECS), we have an article called “The worst-case execution-time problem – overview of methods and survey of tools”. “We” is kind of understatement, the article has fifteen authors from three continents, and presents an overview of the state of the field of WCET (Worst-Case Execution Time) analysis. The article was started back in 2005, with submission in 2006, accepted in January of 2007, and then finally it appeared in 2008. It is probably my last shot in the WCET area where I did my PhD thesis (please see my list of publications for an idea of what all of that is about).
Power.org publishes a quarterly newsletter over at www.power.org/news/newsletter. In the April 2008 issue it features a short article by me introducing Simics 4.0 and Simics Accelerator, the way in which Virtutech Simics takes advantage of multicore processors to simulate large target systems using a multithreaded simulator.
I have an article at SCDSource.com, about how virtual platform creation needs to become more efficient. And the Virtutech current solution to that issue, DML, Device Modeling Language. There is no need to repeat the contents here, just head over to www.scdsource.com/article.php?id=166 to read it! I really think that DML has something to contribute in the world of virtual platforms. We need to find ways to be more efficient about how to create models, and that means creating a better programming language.
So what is SCDSource? Is is a quite good news and analysis site about the electronics industry, EDA, virtual platforms, and other themes close to my heart. SCDSource was started in October 2007, and have produced a series of good and interesting articles since. They tend to actually write articles and not just repeat press releases, and to report form interesting panels at events like DATE, ESC, and Multicore Expo.
The “Handbook of Real-Time and Embedded Systems” (ToC, Amazon, CRC Press) is now out. I and my university research colleague and friend Andreas Ermedahl have written a chapter on worst-case execution time analysis. We talk some about the theories and techniques, but we try to discuss practical experience in actual industrial use. Both static, dynamic, and hybrid techniques are covered.
I just got my personal copy, but my first impression of the book overall is very positive. The contents seems quite practical to a large extent, not as academic as one might have feared. Do check it out if you are into the field. It is not a collection of research paper, rather instructive chapters informed by solid research but with applications in mind.