• Problems with the giac package : different failures on buildd and porte

    From Julien Puydt@21:1/5 to All on Wed Jan 22 22:10:02 2020
    Hi,

    I uploaded a new giac to unstable ; this package was building ok
    everywhere when it was last uploaded (a long time ago, september 2018),
    but now fails on s390x.

    It's a scientific computation package, and the build process consists
    in essentially three steps :
    - build the source ;
    - build the documentation, running the executables from the previous
    step to show off their use ;
    - run the checks, by running the executables from the first step on
    stranger inputs, stressing the corner cases.

    The buildd managed went through the first two steps, but only a few
    tests ran, and already with a few failures (already a problem), until
    one of them had to be killed after a while, presumably because it was
    stuck (complete story here: https://buildd.debian.org/status/fetch.php?pkg=giac&arch=s390x&ver=1.5.0.85%2Bdfsg1-1&stamp=1579706992&raw=0
    ).

    I wanted to work on it and get meaningful data for upstream, so turned
    to zelenka, the porterbox for this architecture. I followed the
    tutorial here https://dsa.debian.org/doc/schroot/ - as I'm already used
    to do when I get problems with other packages. But this time, the
    documentation step already fails :
    *** bug in PARI/GP (Segmentation Fault), please report.
    (repeated quite a few times before the compilation dies)

    I don't understand why I get so wildly different outcomes with the same
    source package : did something get into unstable and break things
    between the time the buildd ran and the time I tried to reproduce the
    issue ? Do you have any advice ?

    Thanks,

    JP

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  • From Julien Puydt@21:1/5 to All on Thu Jan 23 08:10:01 2020
    Le mercredi 22 janvier 2020 à 21:29 +0100, Julien Puydt a écrit :

    I wanted to work on it and get meaningful data for upstream, so
    turned
    to zelenka, the porterbox for this architecture. I followed the
    tutorial here https://dsa.debian.org/doc/schroot/ - as I'm already
    used
    to do when I get problems with other packages. But this time, the documentation step already fails :
    *** bug in PARI/GP (Segmentation Fault), please report.
    (repeated quite a few times before the compilation dies)


    The compiled calculator gives strange results:
    1/2.0-1/3
    5.46834151467e-304
    // Time 0
    1/2.0
    3.64556100978e-304
    // Time 0
    1/3
    1/3
    // Time 0
    1/1.
    3.64556100978e-304
    // Time 0
    1.
    3.64556100978e-304
    // Time 0

    The last example shows that it's not just a computation problem.

    There's something extremely fishy on that box!

    JP

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  • From Aurelien Jarno@21:1/5 to Julien Puydt on Wed Feb 5 21:40:01 2020
    On 2020-01-23 07:52, Julien Puydt wrote:
    Le mercredi 22 janvier 2020 à 21:29 +0100, Julien Puydt a écrit :

    I wanted to work on it and get meaningful data for upstream, so
    turned
    to zelenka, the porterbox for this architecture. I followed the
    tutorial here https://dsa.debian.org/doc/schroot/ - as I'm already
    used
    to do when I get problems with other packages. But this time, the documentation step already fails :
    *** bug in PARI/GP (Segmentation Fault), please report.
    (repeated quite a few times before the compilation dies)


    s390x is a big-endian architecture. The build failure on ppc64 and
    sparc64 are really similar, so I believe the issue is related to
    endianness.

    The compiled calculator gives strange results:
    1/2.0-1/3
    5.46834151467e-304
    // Time 0
    1/2.0
    3.64556100978e-304
    // Time 0
    1/3
    1/3
    // Time 0
    1/1.
    3.64556100978e-304
    // Time 0
    1.
    3.64556100978e-304
    // Time 0

    The last example shows that it's not just a computation problem.

    That behaviour clearly shows that what is displayed is not the result of
    the computation.

    --
    Aurelien Jarno GPG: 4096R/1DDD8C9B aurelien@aurel32.net http://www.aurel32.net

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