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A read-only root for Slackware ARM

Sunday 20 April 2014, 16:52

In my last posting I described getting Slackware ARM to boot headless on the ODROID U3 single-board computer, and I said that the next step would be to try to make it handle ungraceful shutdown (power loss) better. I plan to put this board into a Eurorack synthesizer module with no easy access to the microHDMI monitor connection, and SSH over the Ethernet connection as the only access to administrative functions. If, when the power is pulled on it, it comes up on next boot in a state where it requires console interaction to do a step like checking the filesystem before it will accept SSH connections, that is a disaster; I'd have to disassemble the whole module to extract the microSDMI card and replace the OS image. To be useful, the ODROID must be guaranteed or almost guaranteed to survive a power drop and come up SSH-able on the next boot. Ideally, I want pulling the plug on it with no shutdown formalities to be the normal expected way of shutting it down too, not just an error condition from which it can recover. A good journalling filesystem can increase the chance of recovery from occasional accidental power drops, but I think the only way to make routine non-accidental power drops safe is to keep the filesystem mounted read-only - which might be desirable anyway, to reduce wear on the flash memory and prevent its being corrupted by other kinds of accidents. So this posting is about my experiences configuring Slackware ARM on the ODROID U3 to keep its root filesystem read-only.

Slackware on the ODROID U3

Sunday 13 April 2014, 18:20

Our last episode concluded with the discovery that the clip leads I was using to power the ODROID U3 had nontrivial resistance, possibly close to two Ohms for the pair. That's a lot, when one is pulling up to 2A through them from a 5V supply. I switched them for some lower-resistance ones, and the ODROID seemed to behave much better. Between that and a replacement of the Hardkernel-supplied microSD card, I was hopeful that the reliability problems would be much reduced and I could make some progress on the software side of things.

More ODROID adventure, or "Young man, in this household we obey Ohm's Law"

Wednesday 9 April 2014, 20:39

As of last update, I had given up on setting up the ODROID U3 without connecting a monitor to it, and was shopping for a micro-HDMI cable. Here are some further notes

Some notes on the ODROID U3

Sunday 6 April 2014, 20:09

I recently bought a Hardkernel ODROID U3 single-board computer to use in one of my projects. The ODROID U3 is an ARM-based computer capable of running Linux or Android, with Ethernet, USB, microSD, and some other ports that I wasn't planning to use. My plan is to use it for controlling a music synthesizer, with the USB ports used to interface to the synth and a little LCD panel, and the Ethernet port used to talk to other computers. This posting contains some notes on getting it to work.