https://bugs.kde.org/show_bug.cgi?id=414541
--- Comment #5 from Alexander Semke <alexander.se...@web.de> ---
(In reply to nijso from comment #4)
> Hi, I have the most recent version of libspectre, 0.2.8. I re-compiled
> libspectre and cantor and it still crashes, also for the previous cantor
> version 19.08 (I thought that one worked, but unfortunately it doesn't work
> either. I tried cantor 18.04 but that one crashes when I load it).
I'm also on openSUSE and also observed this crash in the past. The crash
disappeared later and I never managed to look into this. Now it's crashing
permanently for me and I had a closer look into it.
The crash happens in glibc in the memcopy call (Cantor -> Spectre ->
GhostScript -> Little-CMS -> GNU C lib). Modern versions of glibc use the
AVX-optimized implementations where the propper AVX-instructions are
used/generated depending on the available CPU-features ("CPU-dispatching",
https://lwn.net/Articles/691932/). On my and on your computer the CPU has the
AVX extension and we go into the AVX-case where __memmove_avx_unaligned_erms is
used. But, this generates "somehow" an instruction which is not recognized by
the CPU(?) and the process crashes.
Recompiling glibc without AVX-optimization or patching the compiled library as
described in
https://stackoverflow.com/questions/42451492/disable-avx-optimized-functions-in-glibc-ld-hwcap-mask-etc-ld-so-nohwcap-for/44468494#44468494
will help here but is surely not an option for everybody.
I'm not sure how to deal with this now. This problem is clearly outside of
Cantor.
We introduced the support for Jupyter notebooks recently:
https://sirgienkogsoc2019.blogspot.com/2019/08/cantor-and-support-for-jupyter.html
Here, for the mathematical formulas embedded into the text we also use LaTeX to
generate the images. We use pdflatex to generate PDF and to render it to an
image via Poppler. For general latex entries in the worksheet we use latex as
the renderer and the path is tex->EPS->libspectre->image - this is where the
crash happens. Since we now require pdflatex anyway for the support of Jupyter
notebooks, we should maybe completely switch to pdflatex also for normal latex
entries in the worksheet. This will simplify the code a bit and also avoid this
crash in the AVX-optimized glibc on openSUSE and maybe on some other
distributions.
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