[Ksummit-2012-discuss] [ATTEND] kernel core dump and "dying breath"

Jason Wessel jason.wessel at windriver.com
Thu Jun 21 10:57:29 UTC 2012

On 06/21/2012 05:37 AM, Konrad Rzeszutek Wilk wrote:
> On Thu, Jun 21, 2012 at 4:05 AM, Cong Wang <xiyou.wangcong at gmail.com> wrote:
>> Hi, all,
>> I would like to bring up the kernel "dying breath" topic with
>> to the Kernel Summit this year. It will contain some recent
>> technologies like pstore, ramconsole etc., and of course
>> should also cover kdump and netconsole too.

If we are going to make netconsole actually work reliably in all
contexts, kgdboe can be revived.  Currently there are places
netconsole simply doesn't work and that printk you were looking
for... It is never going to be delivered.

> Are there any future projects in the pipeline? Most of these deal with
> depositing somewhere "why it crashed" information, but are there any
> that try to omit the cause on the next boot?

Self healing eh?  Short of using a different kernel to run some
scripts to look at the crash itself and take action such as booting a
new kernel, OR booting the existing kernel and looking at the previous
crash information to attempt to take corrective action I am not aware
of anything.  Things like fsck take this sort of action today, I
believe you are asking about something of an entirely different level.

The one thing that does come to mind is that if you did save
information about the prior crash that you could probably get more
information on the next next crash by automatically inserting a kprobe
at the crash address that could collect more information automatically
into the ftrace buffer or "something" depending on the original crash.

For the really tricky sorts of problems like memory corruption
however, the addresses tend to move around so this is not likely to
help much.  I tend to fall back to kdb, and the "kdb death script" (a
toy of mine that is not in the mainline), where you can assign an
action to output all the commands you would have other wise typed, and
then reboot.


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