kcon

I was asked to review an eBook based on a blog post I wrote a while back on raw sockets in the Boost.Asio C++ library:

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I about tore my hair out on this one. The guys who make the Angstrom distribution of Linux have a script called “mkcard.txt” (http://www.angstrom-distribution.org/demo/beagleboard/) which has traditionally worked for me to format an SD card properly for the Beagleboard family of single-board computers.

But for some reason whenever I would run it in the last month or so on either Ubuntu 10.04 or Ubuntu 12.04, I would receive the following error and the card would not be properly formatted:

/dev/sdb2 is apparently in use by the system; will not make a filesystem

I found a path to the solution thanks to this askubuntu.com question: http://askubuntu.com/questions/124565/mkfs-vfat-unable-to-open-dev-sdg1-device-or-resource-busy/164106#164106.

There seem to be two problems. The first is that dmsetup is stealing the SD card devices.

The second problem is that the script calls “kpartx” to add a partition mapping of the SD card you’re using to the /dev/mapper folder. In English, this means that it will take the drive string (“/dev/sdb” in my case), mount the partitions on the drive, and create device files for them in /dev/mapper. I’m not sure why this causes the script to fail, but I’m guessing the system isn’t relinquishing control of the partition device files to the script so it can run mkfs.vfat and mke2fs on them.

So anyway, to make the mkcard.txt script work, first run it once (and experience the error I referenced above).

Then, remove the stolen devices from dmsetup by running:

sudo dmsetup remove sdb1

sudo dmsetup remove sdb2

Finally, comment out the following lines in mkcard.txt from this:

if [ -x `which kpartx` ]; then
       kpartx -a ${DRIVE}
fi

To look like this:

#if [ -x `which kpartx` ]; then
#       kpartx -a ${DRIVE}
#fi

And run mkcard.txt one more time, and you should be good to go!

Did you know that I had a brief stint as a radio personality? Well, sort of…

When I was an undergraduate at the University of Pennsylvania, I was required to take a writing course. Many of the writing courses Penn offers are unexciting, but I was lucky to enroll in a course called “Writing for Radio.” The class was held at the local independent radio station, WXPN, which was about four blocks away from campus.

The course was a fun diversion from the math and science courses I was taking. We had four instructors, and each one was an actual radio host at WXPN. We spent ten weeks listening to a lot of radio, like news programs on NPR and band interviews that were recorded at WXPN. Our instructors taught us how to speak properly on the radio, like how to break up a radio script into bite-size chunks you can say without running out of breath.

The final project for this course was to go out into the world and interview someone about an event they were hosting. I hopped on a train to Wilmington, Delaware and interviewed a member of the Delaware Theatre Company. She was directing a Christmas play called “It’s a Wonderful Life: A Live Radio Play.” It’s basically the traditional story of “It’s a Wonderful Life,” but they tell it as if it were broadcast on the radio. So the actors and actresses on stage interact with a lot of props to create sound effects during the play. It seemed appropriate for an assignment to create a radio piece.

I really liked how the interview turned out, and WXPN even broadcast it live on the radio! Give it a listen and let me know what you think. Should I eventually return to radio?

Note: The audio levels aren’t that great, so you might turn up your volume to hear it better.