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

Jason Wessel jason.wessel at windriver.com
Fri Jun 22 19:34:38 UTC 2012

On 06/21/2012 01:57 PM, Matthew Garrett wrote:
> pstore has this data and exposes it via a filesystem. It works out of 
> the box for catching panics on EFI systems. BIOS is less capable, but in 
> testing I've found that we can encode adequate data in a QR code 
> assuming a reasonable resolution screen. I've some unfinished code for 
> presenting this, having entirely lacked the time to do anything with it 
> lately.
> (Basic design was as follows: Take the backtrace, compress it, encode in 
> an alphanumeric QR code including an http:// prefix, submit to 
> http://kbu.gs/blah automatically when user takes a picture)

I have to admit I am curios on both fronts.  For pstore, it got me
wondering about what kind of atomic interface exists, and if this is
used in any distros as of yet.  With an atomic interface to pstore
that doesn't touch pieces of the FS handlers that require locks, I
could see this being really useful. The documentation is a bit scant
so I'll probably have to play with this.

Two months ago this would have come in handy for sure.  I thought HEY,
I have a real problem I can use kdb for since my workstation started
randomly crashing where it appeared to just hang in X (required hard
power cycle) and there was zero information in any kind of log after
reboot.  Because the distro kernel had kgdboc, I just turned it on
and waited for the next crash.  When I got the kdb shell and ran
dmesg, it definitely a crash, but it was due to an intermittent HDD
failure where the hard power cycle kept reviving the drive (I called
the same day had it replaced the next).  The point here is I would
have loved having the log to know what happened from the pstore, or a
kdb death script etc, the very first crash. :-)

On the QR Code front, I am curious what the interface to this is?
Atomic KMS and what about goofy cards like Nvidia where you don't
always get KMS?

Certainly I have had developers run kdb to dump a thread list and
other information in similar sorts of hard to debug scenarios where
there was no kdump, and send me jpegs.  Is the interface somewhat
generic and atomic?  It would be nice to be able to dump a pile of
data that you care about and snap a picture and have it show up on my
desktop or customer site -> support etc...


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