Re: [PULL 06/15] tests/qtest/migration: Don't use -cpu max for aarch64

[Peter Xu]

On Wed, Jan 31, 2024 at 10:09:16AM -0300, Fabiano Rosas wrote:
> If we ask for KVM and it falls back to TCG, we need a cpu that supports
> both. We don't have that. I've put some command-line combinations at the
> end of the email[1], take a look.

Thanks a lot, Fabiano.  I think I have a better picture now.

Now the question is whether it'll be worthwhile we (migration) explicitly
provide code to workaround such issue in qtest, or we wait for ARM side
until we have a processor that can be both stable and support KVM+TCG.

I actually personally prefer to wait - it's not too bad after all, because
it only affects the new "n-1" migration test.  Most of the migration
functionality will still be covered there in CI for ARM.

Meanwhile, AFAIU we do have a plan upstream to have a stable aarch64 cpu
model sooner or later that at least support KVM.  If that will also be able
to support TCG then goal achieved.  Or vice versa, if we would be able to
add KVM support to some stable TCG-only cores (like neoverse-n1).

Do we have a plan in this area?  Copy both Peter & Eric.

If we can have that in 9.0 then that'll be perfect; we can already start to
switch migration tests to use the cpu model.

As of now, maybe we can (1) fix the gic-version in migration-test.c to be
stable; this seems a separate issue just to get prepared when a new model
comes, then (2) document above decision in migration-compat-aarch64 test in
.gitlab-ci.d/, if we can reach consensus.  Then we only rely on x86 for
"n-1" migration tests until later.

-- 
Peter Xu