TeachingOpenSource Planet

The PandaStack I mentioned previously - a stack of PandaBoards mounted on threaded rods, powered by a modular ATX power supply - is now a fully-functional part of the Fedora ARM project koji buildsystem.

For anyone interested in building a similar stack, here's the parts list and assembly instructions:

• 15 PandaBoards (or whatever quantity you wish to stack; the photo here shows 11 boards, since we have temporarily removed 4 for various device driver test projects)
• 15 barrel connectors
• 1 ATX 750W modular power supply (note: higher-rated power supplies may not have more current available on the +5v rail, which is what is used in this project)
• 4 threaded #4-40 stainless steel rods. (Note: BeagleBoards accept a #6-32 thread, but PandaBoards have smaller mounting holes).
• 1 pack (100) 0.25" nylon spacers
• 1 pack (50) 1.25" nylon spacers
• 2 packs (10) stainless steel acorn nuts
• SD cards, ethernet cables, network switch
• hacksaw, soldering iron, solder, wire strippers, heat-shrink tubing, heat-shrink gun (or embossing craft gun), multimeter

Cut the threaded rods to size with the hacksaw. Stack the boards on the rods, reversing the orientation of every second board so that it is upside down with the ethernet jack facing the opposite side of the stack; this will result in ethernet and power jacks down two opposite sides of the stack, with serial ports on another side and no connectors on the remaining side (which is the "bottom" of the stack). Use the 1.25" spacers between adjacent boards in a right-side-up/upside-down pair, and the 0.25" spacers between pairs. The grounding strips on the top of each ethernet/USB connector tower will just touch the plastic cases of the LED drive transistors on the adjacent board in each pair. Fasten the stack with the acorn nuts.

Gather the barrel connectors in groups of five. Connect each group to the +5 volt (pin 1) and ground (pin 2/3) leads of a molex connector from the ATX power supply (cutting off the cable connected to the molex connector, and ensuring that the barrel connectors are wired center-positive). Solder, then insulate with shrink-wrap tubing. Take the motherboard connector of the power supply, pull off all of the leads except pins 8 (PWR_OK)  and 16 (PS_ON), solder those leads together, and insulate with shrink-wrap tubing. Plug the molex and motherboard connectors into the ATX supply.

Place the stack on its side on a wire shelf for convection cooling. Test the power supply leads to ensure you're getting a solid +5 volts, burn and insert your SD cards, connect your ethernet cables, and connect the boards one at a time to the power supply unit with the barrel connectors.

Enjoy your silent tower of computing power!

The Fedora ARM secondary architecture project reached a significant milestone last week with Paul's announcement of the beta 1 release.

Interested in ARM but lacking ARM hardware? Not a problem! Fedora includes support for ARM virtual machines, and I'm packaged up a preconfigured ARM VM for your convenience:

• ARM virtual machine package: http://scotland.proximity.on.ca/arm/armvm/noarch/armvm-f13beta1-15.fc13.noarch.rpm
• Repo config for staying up-to-date on ARM VM releases: http://scotland.proximity.on.ca/arm/armvm/noarch/armvm-release-1-1.fc13.noarch.rpm

The armvm package will install a preconfigured ARM virtual machine named "f13-arm-beta1" with a 2GB image and a 128MB memory footprint. Since x86_64 processors don't provide hardware support for ARM processor virtualization, the ARM VM will run slowly compared to i386/x86_64 VMs, but the performance should be tolerable on most machines (Atom netbooks excepted). You can manage the VM with virsh or virt-manager. I've tested these packages on F13 and F14, but not on F15 Alpha yet. (By the way: the root password on the VM is "fedoraarm").

Enjoy!

(Please don't forget that both the Fedora ARM beta release and the armvm package are very definitely at the pre-release/beta stage of maturity. In particular, updating the armvm package will REPLACE your arm VM with a new image - beware!).

Our "PandaStack" of PandaBoard builders (shown here with 9 of the 15 builders installed) is now ready to run as part of the Fedora ARM build farm. However, I've run into a weird problem -- the ATX power supply I bought to power the boards works fine with 1-3 boards, but Something Bad happens when a fourth board is connected. It's not a capacity issue as far as I can see; it seems to be related to noise. Time to borrow a scope and take a close look at waveforms ... in the meantime, we'll power some of the boards with the ATX supply and some with stand-alone power bricks.

So I've safely arrived at FUDCon. Oddly, our plane was delayed for two reasons: the inbound flight was late due to a storm in Winnipeg (not so odd), and there was a "Coyote Strike" by a plane that landed just before we took off -- so they had to check that the runway area was animal-free before we were cleared for takeoff.

Coyotes in Arizona, yes. But Toronto?!

Looking forward to a great day of talks tomorrow! Hope I have two brain cells awake to rub together -- doubly so for the students, who are now on the prowl for food...

My colleagues in the Centre for Development of Open Technology have been doing some amazing work enhancing the open web. One of their libraries, Popcorn.js, enables web video to move beyond being a box on the page to become a part of the hyperlinked, dynamic web. With a ton of frantic hacking by the Popcorn team which began on Tuesday morning (!), PBS launched an interesting web page that night showing analyst's comments synchronized to a video of the US President's State of the Union speech. PBS comments about the effort are posted on The Rundown.

You should check out what these folks are doing with 3D on the web -- the Javascript port of the Processing data visualization language, Processing.js -- point cloud data -- and web audio!

Update: Dave Humphrey has blogged about the work that he and his team did on the SOTU page with PBS.

This semester is the fourth time that I've run the Software Build and Release (SBR600) course at Seneca College, and we have record enrollment – a full house! This course is one of a number of open source courses connected with the Centre for Development of Open Technology; it is a professional option in our Computer Systems Technology program, which focuses on network and system administration, and it has two goals:

• Teach software build and release (aka Release Engineering/Build Team) principles, technology, and skills
• Teach how to contribute effectively in an open source community

In this course, I use the Fedora build and release process as a illustration of how large-scale build and release works, something which is only possible because of the transparent nature of open source processes. I also use Fedora as a community which is open to worthwhile contributions from any interested participants. In these first three weeks of the course, we've examined building from source, RPM packaging, the use of mock for build dependency testing, the use of koji for multi-platform testing, signing packages, and creating package repositories. The remainder of the semester is largely project-based.

The students are currently researching and selecting projects from a short list of potential projects which have been screened for manageable size and practical real-world value. This semester, many of these projects are focused on the Fedora ARM secondary architecture, since the ARM buildsystem is physically located at Seneca, but some projects are related to different areas within Fedora (or, in one case, Fedora+Mozilla). In all cases, the students are expected to work with the community, use community communication tools and practices, and ultimately, advance the state of the respective area to which their project contributes. That means that if new software is packaged, it will be put through package review and end up in Fedora; if scripts or programs are written, they will be reviewed and committed upstream; and if documentation is written, it will end up in an appropriate and accessible place such as the wiki.

On Friday, ten SBR600 students will be traveling with Paul Whalen and me to FUDCon Tempe – eight students from the current semester and two from the previous semester. They're looking forward to making connections with other Fedorans, hearing about the latest and greatest technology, hacking, and generally starting down the road to becoming active contributors.

Please join us! -- I invite you to check out what we're doing, either in the usual Fedora places or in the #seneca channel on Freenode, on the Seneca wiki, or on Planet CDOT.