Re: [RFC PATCH 2/2] tests/functional: Adapt reverse_debugging to run w/o Avocado

["Daniel P. Berrangé" <berrange@redhat.com>]

On Mon, Sep 15, 2025 at 02:42:07PM +0200, Thomas Huth wrote:
> From: Gustavo Romero <gustavo.romero@linaro.org>
> 
> 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.
> 
> The reverse_debugging test is now executed through running GDB via a
> python script. The test itself is only responsible for invoking
> GDB with the appropriate arguments and for passing the test script to
> 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 [...]'.
> 
> Signed-off-by: Gustavo Romero <gustavo.romero@linaro.org>
> [thuth: Rework the test to run without tests/guest-debug/run-test.py]
> Signed-off-by: Thomas Huth <thuth@redhat.com>
> ---
>  .../functional/aarch64/test_reverse_debug.py  |  16 +-
>  tests/functional/ppc64/test_reverse_debug.py  |  18 +-
>  tests/functional/reverse_debugging.py         | 235 +++++++++++-------
>  tests/functional/x86_64/test_reverse_debug.py |  20 +-
>  4 files changed, 171 insertions(+), 118 deletions(-)
> 

snip

>  
> -        # assume that none of the first instructions is executed again
> -        # breaking the order of the breakpoints
> -        self.check_pc(g, steps[-1])
> -        logger.info('successfully reached %x' % steps[-1])
> +        # Assume that none of the first instructions is executed again
> +        # breaking the order of the breakpoints.
> +        # steps[-1] is the first saved $pc in reverse order.
> +        self.check_pc(steps[-1])
> +        logger.info('Successfully reached %x' % steps[-1])
>  
> -        logger.info('exiting gdb and qemu')
> +        logger.info('Exiting GDB and QEMU...')
> +        # Disconnect from the VM.
> +        gdb.execute("disconnect")
> +        # Guarantee VM is shutdown.
>          vm.shutdown()
> +        # Gently exit from GDB.
> +        gdb.execute('print "test succeeded"')
> +        gdb.execute("exit 0")

This causes immediate terminatino of the python program which prevents
any of the tearDown cleanup logic from running.

> +
> +    @staticmethod
> +    def main():
> +        try:
> +            LinuxKernelTest.main()
> +        except SystemExit:
> +            # If the test is marked with @skipFlakyTest, then it will be exited
> +            # via sys.exit() before we have the chance to exit from GDB gently.
> +            # Because recent versions of GDB will return a failure value if this
> +            # happens, we catch the SystemExit and exit from GDB gently with 77,
> +            # which meson interprets correctly as a skipped test.
> +            gdb.execute("exit 77")
> +
> +if __name__ == '__main__':
> +    if not _has_gdb:
> +        sys.exit("This script must be launched via tests/guest-debug/run-test.py!")

This is incorrect.

> +    ReverseDebugging.main()


With regards,
Daniel
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