3 ms·

I debugged a boot issue on the Apple Newton this way. The latest flash image was a brick on production hardware (no available LEDs, GPIOs, etc.) but not on deve

by kabdib 9y ago

I debugged a boot issue on the Apple Newton this way. The latest flash image was a brick on production hardware (no available LEDs, GPIOs, etc.) but not on development hardware. But I could flash a new OS image. So I wrote some small loops that did different stuff on the bus (so that they sounded different) and salted the boot path with them, then listened in on my portable AM radio. Found the problem inside of an hour by moving the loops further down the path. There were probably other ways to do this (could have coaxed a hardware tech in the lab to solder in a GPIO), but this way was more fun. :-)

tzahola 9y ago
What was the problem?
- kabdib 9y ago
  IIRC it was some improperly guarded code that was intended to run only on the non-production development systems (some debugging support). The kernel would touch a non-existent h/w register and trap, which was fatal. Removing the code was the fix.
z3t4 9y ago
meanwhile on the web: "The undefined variable foo on line 13 is not a function"
phyzome 9y ago
Reminds me of the CHDK hackers trying to dump firmware off a Canon camera. They could get the altered firmware to activate and could read memory and control an LED, so... they blinked the firmware out through the LED, and read it with a ball mouse's optical sensor attached to a microphone cord. :-)
- nyreed 9y ago
  I half-remember reading that someone dumped the firmware of an older iPod by listening to hard disk noises. Thinking back this doesn't make much sense. EDIT: I was maybe ⅓ right https://web.archive.org/web/20070613032334/http://www.ipodlinux.org/stories/piezo/ https://web.archive.org/web/20070613032334/http://www.ipodli...
  - deleted 9y ago
    [deleted]
banku_brougham 9y ago
To a non-hardware guy this sounds like strange witchcraft. Very cool.
cgb223 9y ago
Thats probably the most commitment I've ever seen for fixing a bug like that Thats awesome
maxxxxx 9y ago
Logging by sound? I love it.

by kabdib 9y ago

tzahola 9y ago

What was the problem?

kabdib 9y ago
IIRC it was some improperly guarded code that was intended to run only on the non-production development systems (some debugging support). The kernel would touch a non-existent h/w register and trap, which was fatal. Removing the code was the fix.

z3t4 9y ago

meanwhile on the web: "The undefined variable foo on line 13 is not a function"

phyzome 9y ago

Reminds me of the CHDK hackers trying to dump firmware off a Canon camera. They could get the altered firmware to activate and could read memory and control an LED, so... they blinked the firmware out through the LED, and read it with a ball mouse's optical sensor attached to a microphone cord. :-)

nyreed 9y ago
I half-remember reading that someone dumped the firmware of an older iPod by listening to hard disk noises. Thinking back this doesn't make much sense. EDIT: I was maybe ⅓ right https://web.archive.org/web/20070613032334/http://www.ipodlinux.org/stories/piezo/ https://web.archive.org/web/20070613032334/http://www.ipodli...
- deleted 9y ago
  [deleted]

banku_brougham 9y ago

To a non-hardware guy this sounds like strange witchcraft. Very cool.

cgb223 9y ago

Thats probably the most commitment I've ever seen for fixing a bug like that Thats awesome

maxxxxx 9y ago

Logging by sound? I love it.