Re: snek testsuite breaks in 10.1 for qemu-system-arm on armhf

[Stefan Hajnoczi <stefanha@redhat.com>]

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On Thu, Aug 21, 2025 at 02:52:46PM +0200, Christian Ehrhardt wrote:
> Hi,
> Debian and Ubuntu run the self tests of snek as integration tests like:
> 
> `make SNEK_NATIVE=/usr/bin/snek SNEK_ARM=/usr/share/snek/snek-arm
> SNEK_RISCV=/usr/share/snek/snek-riscv -C test check`
> 
> Those tests recently generated signal by failing in the arm emulation
> tests with `qemu-system-arm` - full log [1].
> 
> ```
> 224s Running test pass-precedence.py.
> 224s     pass python3
> 224s     pass snek
> 224s pass-precedence.py:72 Syntax error at "".
> 224s     ***************** snek-arm fail *********************
> 224s     pass snek-riscv
> ```
> 
> 14 tests failed, but all with quite similar signatures.
> 
> But that only happens when executed on armhf, the other host
> architectures are all happy [2].
> 
> I've separated the test and ran a git bisect on qemu 10.0 -> 10.1 as
> somewhere here is the trigger.
> That worked fine and identified this change [3].

CCing Richard Henderson since this was bisected to the following commit:

commit cf4905c03135f1181e86c618426f8d6c703b38c0
Author: Richard Henderson <richard.henderson@linaro.org>
Date:   Sun Jan 12 20:29:41 2025 -0800

    tcg: Convert deposit to TCGOutOpDeposit

> 
> I must admit, I was able to debug it until here, but I can't see how
> these snek test failures could be caused by that change.
> And yes - arm emulation on an armhf platform isn't the most common scenario.

QEMU v10.1.0-rc4 has been tagged and the final QEMU v10.1.0 release is
scheduled for Tuesday, August 26th. I think a fix for this issue can go
through the -stable tree and be released as part of QEMU v10.1.1 since
the number of users affected appears to be small. Please let me know if
you disagree.

Thanks,
Stefan

> 
> I can't predict if there is anything wrong in snek which now is
> treated differently by qemu to trigger this or if snek is all fine and
> qemu broken something - Therefore I've also reported it to snek [4].
> 
> The tracking of the initial finding in Ubuntu is here if you want to
> see more about how this commit was identified [5].
> 
> [1]: https://autopkgtest.ubuntu.com/results/autopkgtest-questing/questing/armhf/s/snek/20250818_045020_246a4@/log.gz
> [2]: https://autopkgtest.ubuntu.com/packages/s/snek
> [3]: https://salsa.debian.org/qemu-team/qemu/-/commit/cf4905c03135f1181e86c618426f8d6c703b38c0
> [4]: https://github.com/keith-packard/snek/issues/103
> [5]: https://bugs.launchpad.net/ubuntu/+source/qemu/+bug/2121124
> 
> -- 
> Christian Ehrhardt
> Director of Engineering, Ubuntu Server
> Canonical Ltd
> 

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