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

manty kuma mantykuma at gmail.com
Tue Jun 1 02:06:51 EDT 2021


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 <greg at kroah.com> wrote:

> On Tue, Jun 01, 2021 at 02:33:50PM +0900, manty kuma wrote:
> > 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?
>
> > 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.)
>
> good luck!
>
> greg k-h
>
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