How to debug spontaneous resets?

I installed Ubuntu 18.04 LTS (GNU/Linux 4.9.40 aarch64) on my VIM2 using @numbqq’s Fenix branch on the eMMC. Unfortunately the device randomly reboots sometimes. It seems to be related to heavy disk usage.

For example when syncing the Bitcoin blockchain it often happens when it’s deleting data from disk. Afaik it was not out of memory. It also reliably happens when I try to format the SD card sudo mkfs.ext4 /dev/mmcblk1p1 during the Creating journal (262144 blocks): stage.

I saw the same behavior with the official VIM2_Ubuntu-xenial_Linux-4.9_mate_arm64_EMMC_2018-05-31 image.

The device is connected via the USB-C port to a 10W adapter. I tried a different adapter as well. I also tried adding a 5W external power source to the other USB port.

My guess is it’s a hardware defect, but is there any way to narrow it down?

Try this:

sudo systemctl disable watchdog

After that, reboot, your problem might get resolved.

Have fun!

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Thanks, I’ll give that a shot. There’s nothing in /var/log/watchdog though, is it supposed to log these resets?

@numbqq might help you out.

Have fun!