[Octave-bug-tracker] [bug #55395] Java tests messes up the stack limits, causes failure of sparse/bicgstab.m

[Stefan Brüns]

Follow-up Comment #9, bug #55395 (project octave):

Ok, the segfault in the JVM cpu probing was a red herring. I am elaborating
here for future reference, although it is not actually related to this bug.

The forced segfault was introduced here:
https://github.com/JetBrains/jdk8u_hotspot/commit/d2dc33eab19e26360bbaa15450b0686b69cb282c#diff-ade79d50bf46023a5dd26524c1a7945b

and is used to disable AVX when a linux kernel bug is present

    // Some OSs have a bug when upper 128bits of YMM
    // registers are not restored after a signal processing.
    // Generate SEGV here (reference through NULL)
    // and check upper YMM bits after it.
    //


"Some OSs" actually is 32bit userspace using a 32bit kernel on a 64bit machine
(implied by AVX).

The kernel bug has been fixed 3 years ago:
https://lore.kernel.org/patchwork/patch/616662/
I.e. anyone using Linux >= 4.4-rc2 or a 64bit kernel does not need this piece
of code.

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