Bug#839898: Acknowledgement (libopenblas-base: Segmentation fault on calling expm() from Octave with libopenblas-base)

[Sébastien Villemot]

Control: tags -1 + moreinfo

Dear David,

Le jeudi 06 octobre 2016 à 09:01 +0000, David Lindelöf a écrit :
> Here is how to reproduce the issue. From Octave, run

> load crashexpm
> expm([[a b]*t; zeros(nb,n+nb)])

I can't replicate your problem on my system. This may be due to the fact
that I have a different CPU from yours: OpenBLAS has a different kernel
for each microarchitecture, and the bug you encountered is probably
specific to yours.

Here are a few inquiries:

- if you have access to a Debian unstable system on the same hardware,
are you still able to replicate the bug? Debian unstable has a more
recent version of OpenBLAS (0.2.19), which may already contain a bugfix.
If you don't have a Debian unstable system, you can create one inside a
chroot (see https://wiki.debian.org/chroot for some explanations)

- I need to know which OpenBLAS kernel you are using. The easiest way of
figuring it is to install the "julia" package, then run "julia" at the
shell prompt, and then type "versioninfo()" at the julia prompt. Then
copy/paste the output

- is it possible to have a backtrace of the crash? Please install the
octave-dbg package (unfortunately there is no debug package for OpenBLAS
in Debian jessie). Then run octave from gdb, and get a backtrace. See
https://wiki.debian.org/HowToGetABacktrace for more details (note: the
part on automatic debug packages only applies to Debian unstable, not to
Debian jessie)

Best,

-- 
 .''`.    Sébastien Villemot
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