July 2008 – Observations from Uppsala

Virtual Platforms for Late Hardware and the Winds of History

As might be evident from this blog, I do have a certain interest in history and the history of computing in particular. One aspect where computing and history collide in a not-so-nice way today is in the archiving of digital data for the long term. I just read an article at Forskning och Framsteg where they discuss some of the issues that use of digital computer systems and digital non-physical documents have on the long-term archival of our intellectual world of today. Basically, digital archives tend to rot in a variety of ways. I think virtual platform technology could play a role in preserving our digital heritage for the future.

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Book review: Taxonomies for the … Digital Systems

The book “Taxonomies for the Development and Verification of Digital Systems“, edited by Brian Bailey, Grant Martin, and Thomas Andersson, was published in 2005 by Springer Verlag. It is a legacy of the defunct VSIA, and presents an attempt to bring order to nomenclature and taxonomies in the chip design field (its scope is defined to be broader than that, but in essence, the book is about SoC design for the most part).

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What’s the Obsession with C in EDA?

In early July, Cadence announced their new “C2S” C-to-silicon compiler. This event was marked with some excitement and blogging in the EDA space (SCDSource, EDN-Wilson, CDM-Martin, to give some links for more reading). At core, I agree that what they are doing is fairly cool — taking an essentially hardware-unrelated sequential program in C and creating hardware from it. The kind of heavy technology that I have come to admire in the EDA space.

But I have to ask: why start with C?

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Off-topic: The Train to Furuvik

This is a short travel tip for the Uppsala-Stockholm area. Yesterday, I used the UL train to get to the Furuvik zoo/amusement park close to Gävle. Compared to the visit we did last year using a car, taking the train was generally a superior experience. And cheap. For 200 SEK, you get two adults + three children, with all rides included. Much cheaper than going there by car and then buying the rides. Not having to spend an hour driving with children is also a clear advantage in my mind, rather you can relax on the train and have fun with the kids. Being tired at the end of the day, I was very happy not to have to drive home.

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Kunle Olukotun Interview: Heterogeneity, Domain-Specific Programming

The Radio Register has a nice interview with Kunle Olukotun, the man most known for the Afara/Sun Niagara/UltraSparc T1-2-etc. design. It is a long interview, lasting well over an hour, but it is worth a listen. A particular high point is the story on how Kunle worked on parallel processors in the mid-1990s when everyone else was still chasing single-thread performance. He really was a very early proponent of multicore, and saw it coming a bit before most other (general-purpose) computer architects did. Currently, he is working on how to program multiprocessors, at the Stanford Pervasive Parallelism Laboratory (PPL). In the interview, I see several themes that I have blogged about before being reinforced…

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EETimes Article on Multicore Debug

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.

Is Cycle Accuracy a bad Idea?

In a funny coincidence, I published an article at SCDSource.com about the need for cycle-accurate models for virtual platforms on the same day that ARM announced that they were selling their cycle-accurate simulators and associated tool chain to Carbon Technology. That makes one wonder where cycle-accuracy is going, or whether it is a valid idea at all… is ARM right or am I right, or are we both right since we are talking about different things?

Let’s look at this in more detail.

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SCDSource Article: Combining Fast and Detailed Models

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.

Off-topic: Numbered Headings in Word 2007

I finally switched to Microsoft Office 2007 in June this year. I was very hesitant, but I have been very pleasantly surprised by how well the new GUI works and how easy it is to get things done – once I stop trying to do things in the old way of Word.

But every once in a while, you get totally stumped trying to do something that was dead easy in “old” Word versions. Once such instance was a colleague of mine totally failing to figure out how to number the headings in the document. Which is pretty standard in technical writing. It took me a while, but I did figure it out. As I could not find any good link on the web explaining how to do this, here is my take that I hope some other desperate soul can search for and find.

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Power Architecture Conference slides online

Power.org Logo The slides from the Power Architecture Conference in München and Paris are now online (and have been for a few weeks) at the Power.org site for the event. Some interesting things there about Power Architecture in particular but also virtual platforms were an almost main theme of the show.

Off-topic: Olle Gällmo, Riksspelman

I just saw in UNT that an old colleague of mine, Olle Gällmo, (his personal website is at olle.gallmo.se) professor in Computer Science, has been appointed “Riksspelman”. Which is a very high accolade for a folk musician. I know that Olle has been working on his bagpiping (if that is the word to use) for a long time, taking it seriously indeed. But still, that is really very impressive work! Congratulations, Olle! I guess I have to pick up the record he just got published as well.

Building a Wooden Deck and Computer Simulation

I just spent the first week of Summer vacation practising the Swedish national sport of home renovation. It seems that everyone is doing that all the time nowadays – it might be that I have reached the age of family raising where that becomes important, or it might be that it is a general trend that more people spend more time and money renovating their homes. I think it is the second case.

Anyhow, what we set out to do this year was to replace (most of) the twenty-year-old wooden decking on the backside of our small row house with a new one. This was quite an adventure, as we discovered all kinds of interesting designs and problems with the old decking structure. Problems, which do reflect on the realities of computer programming and simulation.

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