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!
Read More →
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.
I have read some recent IBM articles about the POWER8 processor and its hardware debug and trace facilities. They are very impressive, and quite interesting to compare to what is usually found in the embedded world. Instead of being designed to help with software debug, it seems the hardware mechanisms in the Power8 are rather focused on silicon bringup and performance analysis and verification in IBM’s own labs. As well as supporting virtual machines and JIT-based systems!
I am a big fan of proper real decent mechanical tactile clickety-clack keyboards. Writing is my means of communication, creation, and commercial contribution to the world. I write a lot of text – both code and normal language, and I feel that I type faster, more accurately, and produce better text when using a tactile keyboard. I cannot understand how anyone cannot love them once they have their fingers on them. However, mechanical keyboards have a bad reputation for being NOISY. The rest of my family thinks my CoolerMaster Trigger Cherry MX Brown is a bit too noisy when I use it at home. Thus, when I read about the Matias Quiet Pro keyboard, I spent the money and gave it a try. If I could have the feeling of a tactile keyboard without the noise, it would be a wonderful compromise!
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!
The recent news that a hacked version of Apple Xcode has been used to insert bad code into quite a few programs for Apple iOS was both a bad surprise and an example of something that has been hypothesized for a very long time. For the news, I recommend the coverage on ArsTechnica of the XCodeGhost issue. It is very interesting to see this actually being pulled off for real – I recall seeing this discussed as a scenario back in the 1990s, going back to Ken Thompson’s 1983 ACM Turing Award lecture.
Now that Windows 10 has been officially out for a while, I decided to give it a try on one of my home machines. I expect that all my Windows 8.1 machines will be updated eventually – it is a free update, after all, and supposedly things should work just as well as in Windows 8.1. Just with a different user interface. Windows 10 is indeed different from Windows 8.1 in fairly significant ways, and it really feels like what would have come after Windows 7 if Windows 8 hadn’t come between. I can see why many or even most people see this as the better upgrade path, even if I lament some of the changes made.
I am using DropBox quite a bit to move files around between various machines (nothing confidential, just stuff that I need to move around and that is a tad on the large side). Today, I hit a very issue where I saved screenshots from a Ubuntu machine and waited for them to show up on a Windows machine. And they never did. Confused, I went to the web interface, and the files were indeed in place there. I could download it from the web interface without an issue. Weird. Other files did sync in the meantime, so just what was going on?
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.
On June 30, Wind River (my job) released Simics 5, the latest version of Simics. I have been working with Simics since 2002 now, and the tool is still improving, adding new features, and adopting the current world. The announcement blog post provides an overview of the features of the new release, and we will be doing some additional in-depth posts later on.
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 followed-up on my visit to the Bovington Tank Museum in the UK with a visit to the Swedish equivalent, Arsenalen in Strängnäs. It is about 100 km from Stockholm, and thus less far off than the UK variant. Arsenalen is strictly speaking a “vehicle” museum, not just a tank museum, even though a majority of the vehicles on display are indeed tanks or at least armored vehicles.
Last week, I visited the rather wonderful tank museum (http://www.tankmuseum.org/home) at Bovington in England, UK. Fascinating, and I am happy to have seem so many legendary machines for real.
Today, I visited the Portsmouth Historic Dockyard in Portsmouth, UK, together with my kids. Somewhat surprisingly maybe, the kids mostly loved it and I got to see and learn a lot of interesting history. I found it particularly usful to compare the three main ships on display: the 1510 Mary Rose, the 1765 HMS Victory, and the 1860 HMS Warrior. They show both the development and continuity of the Royal Navy over a very long period of time.
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.
There is a new post at my Wind River blog, about the Simics Agent feature that we included in Simics last year. Took a while to get a blog out, as I had so many other things to write about. It was also nice to get a video demo out to accompany the post. The most interesting part about the Simics Agent to me is how much more convenient it is to script a target with an agent on the inside. Too bad that also changes the target software stack a bit — but I do think that that is OK most of the time. As always, the solution has to be designed with the end goal in mind, and there is no absolute right or wrong here. Read the blog post for more details!
I just got hit by a strange behavior in Microsoft word: the comment and format change “balloons” that pop up next to the text when using change tracking and viewing changes started to overflow their allocated balloons. The font used look very funny too. The issue was that a document contained a format specification for these balloons that used a font not present on my system, which in turn caused Word to use something like Courier to display it. Which did not look nice. However, it was easy to solve.
In a dusty bookshelf at work I found an ancient tome of wisdom, long abandoned by its previous owner. I was pointed to it by a fellow explorer of the dark arts of computer system design as something that you really should read. The book was “Fortress Rochester”, written by Frank Soltis, and published in 2001.
I just read an article from IEEE Annals of Computing history about the COMIC Color-Matching Analog computer built and sold by Davidson and Hemmendinger, a US firm. It seems the computer is pretty well known inside the colorant industry, actually, and it provides an interesting example of how to do a good-enough solution to break open the market – while leaving the user in control of the process to build faith in the approach.