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

H. Peter Anvin hpa at zytor.com
Tue Jun 26 16:55:51 UTC 2012

On 06/26/2012 05:48 AM, David Howells wrote:
> H. Peter Anvin <hpa at zytor.com> wrote:
>>> Well, I think `prototype' is a bit strong but we did take a look at the
>>> feasibility of using QR codes for backtraces. The two problems were:
>>>    1. Even without any error correction, the QR code started to get pretty
>>>       large (and unreadable) after more than a few lines of backtrace. This
>>>       should be fairly easy to fix by encoding the data in a more sensible
>>>       manner rather than just verbatim (especially since a backtrace is
>>>       a well-structured log). Maybe you could even gzip the whole thing
>>>       after that too (then sell an android app to gunzip it :p)
>> Yes, this is the problem... the QR spec allows for large symbols, but unless
>> you can find at least *one* decoder which can *reliably* decode large symbols
>> photographed under non-ideal circumstances this is all academic.
> Why try and show it all with one huge QR?  Could you not split it into smaller
> pieces and show each as a separate QR, say on a 3×2 grid?

If that turns out to be more reliable, then perhaps that is the way we
have to go.  On the other hand, it introduces more failure modes.

IMO the first thing is to try to find an encoder/decoder chain that can
handle large symbols; if that doesn't work the above might be a good option.


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