tests/functional: Adapt reverse_debugging to run w/o Avocado

This commit removes Avocado as a dependency for running the
reverse_debugging test.

The main benefit, beyond eliminating an extra dependency, is that there
is no longer any need to handle GDB packets manually. This removes the
need for ad-hoc functions dealing with endianness and arch-specific
register numbers, making the test easier to read. The timeout variable
is also removed, since Meson now manages timeouts automatically.

reverse_debugging now uses the pygdbmi module to interact with GDB, if
it is available in the test environment, otherwise the test is skipped.
GDB is detect via the QEMU_TEST_GDB env. variable.

This commit also significantly improves the output for the test and
now prints all the GDB commands used in sequence. It also adds
some clarifications to existing comments, for example, clarifying that
once the replay-break is reached, a SIGINT is captured in GDB.

reverse_debugging is kept "skipped" for aarch64, ppc64, and x86_64, so
won't run unless QEMU_TEST_FLAKY_TESTS=1 is set in the test environment,
before running 'make check-functional' or 'meson test [...]'.

Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Gustavo Romero <gustavo.romero@linaro.org>
Message-ID: <20251003141820.85278-9-gustavo.romero@linaro.org>
[AJB: it is and broke long line]
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Tested-by: Thomas Huth <thuth@redhat.com>

0 files changed, 0 insertions, 0 deletions