[Bug 1935617] Re: systemd autopkgtest broken on ppc64el with qemu 6.0

[Christian Ehrhardt ]

And that matches:

Offending commit:

bcb0b7b1a1c05707304f80ca6f523d557816f85c is the first new commit
commit bcb0b7b1a1c05707304f80ca6f523d557816f85c
Author: Giuseppe Musacchio <thatlemon at gmail.com>
Date:   Mon Nov 9 10:17:11 2020 +0100

    ppc/translate: Rewrite gen_lxvdsx to use gvec primitives
    
    Make the implementation match the lxvwsx one.
    The code is now shorter smaller and potentially faster as the
    translation will use the host SIMD capabilities if available.
    
    No functional change.
    
    Signed-off-by: Giuseppe Musacchio <thatlemon at gmail.com>
    Message-Id: <a463dea379da4cb3a22de49c678932f74fb15dd7.1604912739.git.thatlemon at gmail.com>
    Reviewed-by: Richard Henderson <richard.henderson at linaro.org>
    Signed-off-by: David Gibson <david at gibson.dropbear.id.au>

 target/ppc/translate/vsx-impl.c.inc | 46 ++++++++++++++++++-------------------
 1 file changed, 23 insertions(+), 23 deletions(-)


And if you remember the backtraces above, it was lbzx / lvx / ld that failed which could be implemented that way or conflict the the actual lxvdsx.

And - as always - once you know what you look for it is easier to identify the fix.
I think this one is worth a try:

commit 861f10fd528263a507476b8c4dda93a9588dfa5c
Author: Giuseppe Musacchio <thatlemon at gmail.com>
Date:   Tue May 18 15:30:20 2021 +0200

    target/ppc: Fix load endianness for lxvwsx/lxvdsx
    
    TARGET_WORDS_BIGENDIAN may not match the machine endianness if that's a
    runtime-configurable parameter.
    
    Fixes: bcb0b7b1a1c05707304f80ca6f523d557816f85c
    Fixes: afae37d98ae991c0792c867dbd9f32f988044318
    Resolves: https://gitlab.com/qemu-project/qemu/-/issues/212
    
    Signed-off-by: Giuseppe Musacchio <thatlemon at gmail.com>
    Message-Id: <20210518133020.58927-1-thatlemon at gmail.com>
    Tested-by: Paul A. Clarke <pc at us.ibm.com>
    Signed-off-by: David Gibson <david at gibson.dropbear.id.au>

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Title:
  systemd autopkgtest broken on ppc64el with qemu 6.0

Status in The Ubuntu-power-systems project:
  New
Status in qemu package in Ubuntu:
  New
Status in systemd package in Ubuntu:
  New

Bug description:
  I'm not sure yet if this is flaky or a real issue, but I'm filing it
  to avoid multiple people analyzing the same.

  The Qemu 6.0 upload https://launchpad.net/ubuntu/+source/qemu/1:6.0+dfsg-1~ubuntu2 triggers a test failure like
  https://autopkgtest.ubuntu.com/results/autopkgtest-impish/impish/ppc64el/s/systemd/20210708_223311_e3bbb@/log.gz

  I have tested the new qemu on ppc64 and it worked fine for device emulation and migration cases.
  But this is suspicious.
  Of the last tests exactly and only those with the new qemu failed.

  
  impish
    ppc64el
      tests-in-lxd                   (F  5% f  0% S  0% B  0% => P 95%/) F.........F.............................
      systemd-fsckd                  (F  0% f  0% S 100% B  0% => P  0%/) SSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS
      upstream-1                     (F 15% f  0% S  0% B  0% => P 85%/) F..FFFF....F............................
      upstream-2                     (F 12% f  0% S  0% B  0% => P 87%/) F..FFFF.................................

  
  For an insight in flakyness/reproducibility I've retriggered the missing qemu and the non-qemu cases a few times. If those reproduce all-bad vs all-good again this would further indicate a real issue.

  Unfortunately the ppc maas seems down right now and canonistack also
  isn't too nice this week - overall that inhibits the testing a bit :-/

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