Seneca 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!).

Today, the ATX power supply for the PandaStack I described in my last post is working happily. I have no idea what changed... which is a bit worrisome.

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.

We're adding a group of dual-core, 1GHz, 1GB PanadaBoards to the Fedora-ARM build farm.  Paul Whalen and I hacked up the PandaBoard builder filesystem at FUDCon and I tested it with the farm on Thursday -- so far, it appears to build about twice as fast as the older GuruPlug builders. The PandaBoard's randomly-assigned-at-boot MAC addresses did force us to take a new approach to builder identity, though, because our previous approach of serving the identity via DHCP was no longer practical.

We ordered a total of 15 PandaBoards; 12 have arrived, and the others should be shipped shortly.Two are being set aside for testing, and we'll get the other ten building as soon as possible.

Our plan is to stack the boards on threaded rods, powered by an ATX power supply; the stack will be run on its side (with the boards oriented vertically) to aid in convection cooling. More photos to follow as we get this running! (Yes, that is a Powered by Fedora badge on there )

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...