Bug#1121177: openblas breaks multiple autopkgtest on ppc64el

[Sébastien Villemot]

Dear Trupti,

Le mercredi 07 janvier 2026 à 02:19 +0530, Trupti a écrit :
> On 2026-01-05 19:36, Trupti wrote:
> > On 2026-01-02 11:53, Trupti wrote:
> > > On 2026-01-02 00:34, Paul Gevers wrote:
> > > > user debian-powerpc at lists.debian.org
> > > > usertag 1121177 ppc64el
> > > > thanks
> > > > 
> > > > Dear ppc64el porters,
> > > > 
> > > > On 11/25/25 15:41, Sébastien Villemot wrote:
> > > > 
> > > > > I talked to upstream about the problem (in an issue that was 
> > > > > initially
> > > > > about a FTBFS, due to a failure in OpenBLAS own testsuite, which has
> > > > > since been fixed):
> > > > > https://github.com/OpenMathLib/OpenBLAS/issues/5372#issuecomment-3353517450
> > > > > 
> > > > > Unfortunately upstream does not really know where the test failures 
> > > > > in
> > > > > third-party software come from. In particular, they can’t replicate 
> > > > > the
> > > > > issue (note that they tried with more recent git snapshot than 
> > > > > version
> > > > > 0.3.30), and I couldn’t either with Debian version 0.3.30+ds-3 
> > > > > (tried
> > > > > on the ppc64el Debian porterbox).
> > > > > 
> > > > > At this point, fixing this issue is beyond my time budget and skills 
> > > > > (I
> > > > > know next to zero about PowerPC, and the issue is probably due to 
> > > > > some
> > > > > changes to PowerPC assembly code). CC’ing the Debian PowerPC 
> > > > > porters,
> > > > > with the hope that they can help.
> > > > 
> > > > 
> > > > We're in dire need of your help, the issue is stalling openblas'
> > > > migration to testing and because it's a key package, autoremoval
> > > > doesn't work.
> > > > 
> > > > Paul
> > > 
> > > 
> > > 
> > > Thanks for the ping.
> > > 
> > > I’m currently reproducing the issue on the ppc64el side and
> > > investigating the root cause. Since openblas is a key package, this
> > > needs a proper fix rather than a workaround.
> > > 
> > > Let me go through the bug and I’ll update with findings.
> > > 
> > > Thanks,
> > > Trupti
> 
> 
> Hello Paul,
> 
> I was able to reproduce the autopkgtest failure for xtensor-blas on 
> ppc64el locally. And I have attached both falling and working logs.
> 
> 
> 
> [ RUN      ] xlinalg.pinv
> /tmp/autopkgtest.nrAywe/autopkgtest_tmp/test_linalg.cpp:239: Failure
> Value of: allclose(expected, res)
>    Actual: false
> Expected: true
> [  FAILED  ] xlinalg.pinv (0 ms)
> 
> [----------] Global test environment tear-down
> [==========] 77 tests from 6 test suites ran. (7 ms total)
> [  PASSED  ] 76 tests.
> [  FAILED  ] 1 test, listed below:
> [  FAILED  ] xlinalg.pinv
> 
>   1 FAILED TEST
> make[3]: *** [CMakeFiles/xtest.dir/build.make:70: CMakeFiles/xtest] 
> Error 1
> make[2]: *** [CMakeFiles/Makefile2:188: CMakeFiles/xtest.dir/all] Error 
> 2
> make[1]: *** [CMakeFiles/Makefile2:195: CMakeFiles/xtest.dir/rule] Error 
> 2
> make: *** [Makefile:192: xtest] Error 2
> autopkgtest [23:35:52]: test command2: -----------------------]
> autopkgtest [23:35:52]: test command2:  - - - - - - - - - - results - - 
> - - - - - - - -
> command2             FAIL non-zero exit status 2
> autopkgtest [23:35:52]: @@@@@@@@@@@@@@@@@@@@ summary
> command1             FAIL non-zero exit status 2
> command2             FAIL non-zero exit status 2
> 
> 
> The failure occurs in the test:
> xlinalg.pinv
> test/test_linalg.cpp
> 
> 
> When running the test locally on ppc64el with OpenBLAS 0.3.30, the 
> maximum numerical difference between the expected result and 
> xt::linalg::pinv() output is:
> 
> max diff ≈ 7.0e-09
> mean diff ≈ 2.7e-09
> 
> 
> With the current test tolerance (allclose default / 1e-12), the test 
> fails.
> When the tolerance is relaxed to 1e-8, the test passes consistently and 
> all results are numerically stable.
> 
> This indicates the failure is due to test tolerance rather than a 
> functional regression.
> kindly consider reviewing the test tolerance.

Thanks a lot for your investigation and for the recommendation.

If you have the time, could you possibly also check that the two other
autopkgtest regressions (in src:gemma and src:openmolcas) are also
tolerance-related? (see https://tracker.debian.org/pkg/openblas for the
list of autopkgtest regressions)

-- 
⢀⣴⠾⠻⢶⣦⠀  Sébastien Villemot
⣾⠁⢠⠒⠀⣿⡁  Debian Developer
⢿⡄⠘⠷⠚⠋⠀  https://sebastien.villemot.name
⠈⠳⣄⠀⠀⠀⠀  https://www.debian.org
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