Re: Missing panic logs in /var/log/kern.log

On Tue, Jun 1, 2021 at 2:07 PM manty kuma [off-list ref] wrote:

I am using debian , the logging system being used is rsyslogd.
in /etc/rsyslog.d/default.conf we have rule as follows:

kern.* /var/log/kern.log

This rule I believe is the reason why all the kernel logs are being redirected to /var/log/kern.log.

Also dmesg does not show anything. So, i am pretty sure that all the kernel logs are being handled solely by `rsyslogd`
And this is just the default debian distribution without any customizations.

Thank you for the 'pstore' clue. I will explore it further.

On Tue, Jun 1, 2021 at 2:42 PM Greg KH [off-list ref] wrote:

quoted

On Tue, Jun 01, 2021 at 02:33:50PM +0900, manty kuma wrote:

quoted

I just triggered a panic, expecting that the logs will be visible in
`/var/log/kern.log` after reboot, but there are no logs present there.

I have never heard of kernel logs being written to that location, what
tool do you have that does that and where is that documented?

quoted

Considering I have no access to the serial port, how do I know what went
wrong?

When the kernel panics, it usually can not write to the disk, so it's a
bit hard to save anything :)

That being said, there are ways the kernel can save the crash
information, look into the "pstore" interface and see if that will work
for your hardware platform (it requires hardware to store the
information across boots.)

Also, check kdump, I think it can help as well.

quoted

good luck!

greg k-h

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