Re: [PATCH v3 00/11] tests/migration-test: Allow testing older machine types

[Peter Xu <peterx@redhat.com>]

On Wed, Oct 18, 2023 at 11:19:01AM -0300, Fabiano Rosas wrote:
> Let me point out two situations that came up while developing this:
> 
> 1) There was a generic command line change in QEMU (-audio option)
>    introduced this cycle that was ported to the command line used by
>    libqtest.c. This means that when using the same command line to
>    start both guests, the older one will not recognize the option and
>    will break.
> 
>    Ideally, we would keep command lines out of the library and require
>    each test to provide their own. Then maybe the migration code could
>    cope with the change somehow.

Yeah this is unfortunate, and I hit it as soon as trying this out with an
old binary.

One other thing on top of this: the cross binary tests for different
devices, where we used to hit issues when some specific pci device or a
pcie root port failed to be compatible with old binaries, iirc.

I'm still not sure what's the best way to do that, though, especially if
the migration failure can only trigger when a device driver setup the
device first.  Maybe we can start with migrating a device with the reset
status between binaries.  Having this series is definitely better than
nothing already.

Thanks,

-- 
Peter Xu