Un-Bricking Linux Plug Computers

An anonymous reader writes "Accidentally 'bricking' a little Linux plug computer doesn't have to be forever. This is a good howto on repairing a non-booting Linux plug computer. For example if it uses the uBoot environment then it already has some good built-in recovery tools. The article also mentions ESIA, the Sheevaplug installer, openocd, and GuruPlug."

Comments

Oblig. pedantry

[butalearner]

Isn't the fact that you can "unbrick" it mean it's not really bricked?

Also I think this requires JTAG, which comes with Sheevaplug but is sold separately from Guruplug, and AFAIK is not available on the PogoPlug, et al. So, not quite so useful for me (I just picked up a PogoPlug on the cheap with the intent of running Plugbox Linux.

Re:Oblig. pedantry

[fuzzyfuzzyfungus]

Unless you've decided to mess with uboot(which is likely a bad idea, unless you are totally comfortable with JTAG...), you shouldn't need anything scarier than some way of speaking RS-232 at suitably low voltage. Re-flashing a device over a serial line is tedious; but not terribly challenging, and even the various Kirkwood-platform products that are "no user-serviceable parts inside" almost certainly have an accessible serial header somewhere, albeit likely unpopulated or even unmarked...

If you've gone and nuked the bootloader, on the other hand, it is, as you say, JTAG time...

Re:Oblig. pedantry

[Anonymous Coward]

You haven't done due diligence to pedantry at all; I'm disappointed.

Isn't the fact that you can "unbrick" it mean it's not really bricked?

How bricked is "really" bricked?

I always understood brick to be a measure of subjective usefulness. So if my cellphone is bricked it doesn't necessarily mean it's completely unrecoverable, just that it's not practically recoverable in time to be useful to me, or it will be expensive to recover it, or I don't know how to recover it.

I'm doubtful there's a good objective definition. For instance, you might say "having to replace hardware constitutes brickedness." What if the hardware replacement is trivial, like swapping out a battery? Any definition of non-trivial is going to depend on the skill of the user, and you're back to a subjective definition.

And you could define "bricked" as a physical process. Say, having heated the device to the point where most of the casing and electronics became liquid and then let it cool, that would be well and truly bricked, but it's not a very useful definition.

If you've got a better definition, I'm all ears, but a quick search didn't turn up much for me.

Re:Oblig. pedantry

[Duradin]

They were only literally bricked so they could be easily repaired. Now, if they had been figuratively bricked they'd be literal bricks.

Re:Oblig. pedantry

[idontgno]

Well, -15v is pretty low compared to +15v. Both are officially the lower and upper bounds of the RS-232 signaling voltage range, after all. Certainly, the common -12v "mark" level is much lower (i.e., less positive) than the 3.3v or 5v typical for logic levels nowadays.

Yes, GPP mistakenly conflated "serial" and "RS-232". I'm sure he meant "logic-voltage asynchronous serial". And I'm sure you understood, but that sure was good electronics pedantry.

Re:Oblig. pedantry

[fuzzyfuzzyfungus]

In principle, you are correct. In practice, an increasing number of devices(especially space or cost constrained ones) implement "RS-232" that behaves pretty much exactly the same way as would be expected by anything post-20mA loop, with the exception of voltage. For cost and board space reasons(and because they are not intending to address the "terminal across the electrically noisy building from the minicomputer" use case), they omit any voltage conversion or protection circuitry and simply depend on the attached hardware to do either 5v/0v or 3.3v/0v, or whatever their logic-level happens to be.

Even an increasing number of supposedly-genuine RS-232 devices(especially laptops) don't generate anything near the +-12 swing of the old days. 12v/0v is more likely, or even 5v/0v, though such devices tend to, at least, have better tolerance for over-voltage than the little guys do.

Because it is so close to RS-232(all you need is a dumb level converter, no logic/protocol translation required), I tend to fall into calling it "RS-232" colloquially, even though it technically isn't.

Re:Oblig. pedantry

[butalearner]

With the PogoPlug, all you're doing really on the device is stopping a shell script that's running, and installing a new bootloader. Everything else gets installed on whatever storage device you attach to it, so I think it's probably fairly difficult to properly brick it (although there are more obscure NAND installs that do have the potential to really screw it up).

I actually think Debian is a more obvious choice for these devices than an Arch-based distro as it has more packages than any other distro and has good support for ARM. In my case I really wanted a number of packages that were in Debian, such as byobu and procmail, and I use Ubuntu on the desktop and have always liked Debian-based distros, so it seemed the obvious choice.

Funny story: I actually came across your blog yesterday as I browsed for info about setting up a mail server on the PogoPlug. I'm not sure I'll do it (getting a web server and website up and running is first), but just considering some options. I'm actually an Arch user normally, but I tend to agree that Debian might be better since I don't care about having bleeding edge stuff on there. Thanks for the info!

Re:Oblig. quote response to oblig. pedantry

[Anonymous Coward]

So what you're saying is that you don't think that word means what he thinks it means?

Agree: it's NOT "bricked"

[KWTm]

Isn't the fact that you can "unbrick" it mean it's not really bricked?

Hear hear! Let's recall that "brick" basically means "turning your equipment into something completely worthless, equivalent to a brick".

I propose the following "USB cable" test:

Has your device been rendered so unusable that you'd be willing to give it to me if I gave you a USB cable?

If the answer is "yes", then you have bricked your device. Congratulations.

If the answer is "no, let me work on this for a bit --I think I can restore partial functionality by pressing this reset button for 30 seconds, and then at least it will function as a glorified wall clock", then this is not "bricked".

If you say, "This is the third time I've bricked my device --I had to SSH into it and do 'sudo reboot'" --then the brick is in your brain.

Now, having said this, it's possible that the owner of the computer didn't know it was possible to undo the damage, in which case, yes, the device is bricked because he might as well have traded it in for a USB cable, prior to knowing how to salvage his device.

You can substitute any marginally useful but cheap piece of equipment for "USB cable".

Disclaimer: no, I haven't RTFA.

Oblig Non-Pedantic Question?

[tunapez]

Have they fixed the power supply over-heating/failure issues or are we still talking about the same warts that have a shelf-life of 12 months or less?

I'm serious, I would like an answer b/c I have been wanting one since the first of many, many, many slashvertisements appeared here two, three years ago. Problem is, everything I read on the outside says they fail prematurely and warranty fulfillment is spotty, at best. Am I wrong, Dude?