Re: [PATCH 0/4] tests/functional: Adapt reverse_debugging to run w/o Avocado

[Thomas Huth <thuth@redhat.com>]

On 19/08/2025 16.39, Gustavo Romero wrote:
> The goal of this series is to remove Avocado as a dependency for running
> the reverse_debugging functional test.
> 
> This test, the last one I’m aware of that relies on Avocado, requires it
> because of the need for GDB to test reverse stepping and continue.

  Hi!

Please note that there are currently also some efforts going on to extract 
the GDB part from avocado into a more self-contained python module called 
aautils, which might help here, too:

  https://github.com/avocado-framework/aautils/issues/82

> In this series, we leveraged the run-test.py script used in the
> check-tcg tests, making it a GDB runner capable of calling a test script
> without spawning any VMs. In this configuration, the test script can
> manage the VMs and also import gdb from the test script, making the
> Python GDB API available inside the functional test.
> 
> The test is kept “skipped” for aarch64, ppc64, and x86_64, so it is
> necessary to set QEMU_TEST_FLAKY_TESTS=1 in the test environment to
> effectively run the test on these archs.
> 
> On aarch64, the test is flaky, but there is a fix that I’ve tested while
> writing this series [0] that resolves it. On ppc64 and x86_64, the test
> always fails: on ppc64, GDB gets a bogus PC, and on x86_64, the last
> part of the test (reverse-continue) does not hit the last executed PC
> (as it should) but instead jumps to the beginning of the code (fist PC
> in forward order).

At least the x86 test used to work for me most of the time, it just fails 
occasionally. Same for the ppc64 test if I disable the powernv subtest there.

> Thus, to run the reverse_debugging test effectively on aarch64:
> 
> $ export QEMU_TEST_FLAKY_TESTS=1
> $ make check-functional

I gave it a try, but this did not work for me, the test was not run at all 
anymore. Are there any patches needed on top?

Anyway, shifting to a different test harness here makes me wonder whether 
the whole reverse_debug test should maybe be rather moved to tests/tcg 
instead, where we already have the basic support for the stuff from 
tests/guest-debug/ ?
The aarch64 would require a different guest payload, of course, in that 
case, so not sure whether it's feasible?

  Thomas