Neat Register Design to Avoid Races

raceconditionIn his most recent Embedded Bridge Newsletter, Gary Stringham describes a solution to a common read-modify-write race-condition hazard on device registers accessed by multiple software units in parallel. Some of the solutions are really neat!

I have seen the “write 1 clears” solution before in real hardware, but I was not aware of the other two variants. The idea of having a “write mask” in one half of a 32-bit word is really clever.

However, this got me thinking about what the fundamental issue here really is.

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Freescale P4080, in Physical Form

freescale-logo-iconPast Tuesday, I attended the Freescale Design With Freescale (DWF) one-day technology event in Kista, Stockholm. This is a small-scale version of the big Freescale Technology Forum, and featured four tracks of talks running from the morning into the afternoon. All very technical, aimed at designing engineers.

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Downloadable Book about Embedded Multicore

freescale-logo-iconFreescale has now released the collected, updated, and restyled book version of the article series on embedded multicore that I wrote last year together with Patrik Strömblad of Enea, and Jonas Svennebring, and John Logan of Freescale. The book covers the basics of multicore software and hardware, as well as operating systems issues and virtual platforms. Obviously, the virtual platform part was my contribution.

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LCTES 2010 Call for Papers

The call for paper for LCTES 2010 is now out, the deadline is October 3. If you have something to publish in the area of “Languages, Compilers, and Tools for Embedded Systems”, please consider it! I am on the program committee, and looking forward to reading some really good papers. I used to publish at the LCTES myself when I was doing my PhD… see my older publications if you are curious.

The conference itself will take place in Stockholm in April of 2010, as part of the Cyber-Physical Systems Week (CPSWeek) 2010.

The Hardware-Software Interface is where the Action Is

pn4_quad-gigaswift-utp-adapterWhen I started out doing computer science “for real” way back, the emphasis and a lot of the fun was in the basics of algorithms, optimizing code, getting complex trees and sorts and hashes right an efficient. It was very much about computing defined as processor and memory (with maybe a bit of disk or printing or user interface accessed at a very high level, and providing the data for the interesting stuff). However, as time has gone on, I have come to feel that this is almost too clean, too easy to abstract… and gone back to where I started in my first home computer, programming close to the metal.

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Cadence Industry Insight: “Virtual Platforms Unite HW and SW”

opinionAnother 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.

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EETimes.com – Multicore CPUs face slow road in comms

eetimes logoThe  EETimes article Multicore CPUs face slow road in comms piqued my interest. There is an interesting chart in there about just how slow more-than-one-core processors will be in penetrating a vaguely defined “comms” market place. I can believe that, but I think their comments on the PowerQUICC series require some commentary…

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Enea and Freescale Article on SMP OS

Elektronik i Norden just published a technical insight article about the SMP kernels of Enea OSE and Linux, by Patrik Strömblad and Jonas Svennebring.

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Adding to Schirrmeister’s Virtual Platform Myth Busting

opinionFrank Schirrmeister of Synopsys recently published a blog post called “Busting Virtual Platform Myths – Part 1: “Virtual Platforms are for application software only”. In it, he is refuting a claim by Eve that virtual platforms are for application-level software-development only, basically claiming that they are mostly for driver and OS development and citing some Synopsys-Virtio Innovator examples of such uses. In his view, most appication-software is being developed using host-compiled techniques.  I want to add to this refutal by adding that application-software is surely a very important — and large — use case for virtual platforms.

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Tying a Thread to a Processor in Linux

This is a small Linux SMP programming tip, which I had a hard time finding documented clearly anywhere on the web. I guess people won’t find it here either, but with some luck some search engine will pick up on this.

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“Nulticore Effect”

Jack Ganssle wrote a column about the failure of multicore to scale, based on an article in IEEE Spectrum. He makes the following claim:

Now a study in IEEE Spectrum shows that even for the classic embarrassingly parallel problems like weather simulations multicore offers little benefit. The curve in that article is priceless. As the number of cores grow from two to 64 performance plummets by a factor of five. Additional processors nullify each other.

Call it the Nulticore Effect.

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Off-Topic: The First Snow is Here

The first real snow reached Uppsala this weekend, lots of nice fluffy slippery cold snow on the ground and on the roads and everywhere else. It really is nice to have snow again, it lessens the effect of our dark winters and kind of puts you in a Christmas-like mood, especially now that the Christmas decorations are going up in town and shopping centers.

I also had to bring out the car for some errands and transports yesterday, and that new snow was probably the slipperiest I have ever driven on. It also provided an unsought opportunity for the electronic systems in our car to show themselves… both the stability and traction control and the anti-lock brakes were activated several times despite my pretty careful driving. For some reason, I never really believe that they would apply to me. I know that ESP and ABS are really good for safety, but for some reason I am a diehard skeptic that never quite believe these things work as they should. I guess this is another example of an embedded system that works as it should. Which really should not be a surprise.

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Some surprisingly good embedded systems

I am a skeptic when it comes to technology. Despite working in the tech field — or maybe because I am — I always expect technology to fail or at least disappoint. But sometimes that instinct is actually wrong! Here are two recent examples when I felt “wow, that was pretty good” about some fairly mundane pieces of computerized equipment.

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ChipDesignMag Article on Software in Hardware Design

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.

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