Re: lost busybox mysteriously

Quentin Schulz

Hi JH,

On Mon, Jan 27, 2020 at 10:13:37PM +1100, JH wrote:
Hi Andy,

Thanks for the response.

On 1/27/20, Andy Pont <andy.pont@...> wrote:
JH wrote...

That the same problem of missing busybox was not just occurred during
the device running in the middle of operation, it was also occurred
during booting image from NAND, I saw several times that the first and
second cycles of booting image from NAND were working well, then some
following booting process would be crashed by missing busybox, then
could not run whole shell commands. I have been pondering if it could
be caused by NAND issue or network virus / fishy? Appreciate any
The first step is for us to understand what “missing” means? Have you
got any mechanism (U-Boot, SD card boot, etc.) that will allow you to
mount and look at the contents of the NAND file system?
Means that busybox was not there anymore, it mysteriously lost, all
shell commands would no longer available. It cannot to run mount or
any shell commands. There was two scenarios when that happened:

- In the middle of running, the device all of certain could not run
shell commands and failed mysteriously

- During the u-boot booting kernel process, there were full errors of
failing shell commands. Let me make it clear, that booting error did
not occur in the first or second kernel booting after the new image
installation, it happened in the following kernel booting, but there
was nothing to delete busybox accidentally, busybox was just
mysteriously disappeared. Because I could not run ls, I did not know
if there are other things missing. If you ask how I could know the
busybox was missing, I ran the zImage-initramfs to boot the linux in
RAM, then mount the ubi0 to find out busybox was gone.

If you look at the /bin directory (ls -la /bin/busy*) what do you see?
Have the files been deleted? Truncated? Zero length?
Could not run ls or any shell commands when the busybox was missing.
/bin/ls -la /bin/busy* ?

Maybe something is messing with the PATH environment variable. Or
something is removing the symlinks from some binaries to busybox.

What file system are you using on the NAND flash? How are the devices
being reset during the various boot cycles? If it is a hardware reset
then some file systems are less resilient to it than others but I would
expect in that case more fundamental boot issues.
UBIFS, most device reset or boot cycles were calling halt or reboot,
but it sometime it could just use power cycle.
IIRC, UBIFS is safe from power cycles.


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