Re: [RFC PATCH 3/4] tests/qtest/migration: Add support for simple device tests

[Peter Xu <peterx@redhat.com>]

On Thu, May 23, 2024 at 05:19:21PM -0300, Fabiano Rosas wrote:
> The current migration-tests are almost entirely focused on catching
> bugs on the migration code itself, not on the device migration
> infrastructure (vmstate). That means we miss catching some low hanging
> fruits that would show up immediately if only we had the device in
> question present in the VM.
> 
> Add a list of devices to include by default in the migration-tests,
> starting with one that recently had issues, virtio-gpu. Also add an
> environment variable QTEST_DEVICE_OPTS to allow test users to
> experiment with different devices or device options.
> 
> Do not run every migration test with the devices because that would
> increase the complexity of the command lines and, as mentioned, the
> migration-tests are mostly used to test the core migration code, not
> the device migration. Add a special value QTEST_DEVICE_OPTS=all that
> enables testing with devices.
> 
> Notes on usage:
> 
> For this new testing mode, it's not useful to run all the migration
> tests, a single test would probably suffice to catch any issues, so
> provide the -p option to migration-test and the test of your choice.
> 
> Like with the cross-version compatibility tests in CI and the recently
> introduced vmstate-static-checker test, to be of any use, a test with
> devices needs to be run against a different QEMU version, like so:
> 
> $ cd build
> $ QTEST_DEVICE_OPTS=all \
>  QTEST_QEMU_BINARY=./qemu-system-x86_64 \
>  QTEST_QEMU_BINARY_DST=../build-previous/qemu-system-x86_64 \
>  ./tests/qtest/migration-test -p /x86_64/migration/precopy/tcp/plain
> 
> $ cd build
> $ QTEST_DEVICE_OPTS='-device virtio-net' \
>  QTEST_QEMU_BINARY=./qemu-system-x86_64 \
>  QTEST_QEMU_BINARY_DST=../build-previous/qemu-system-x86_64 \
>  ./tests/qtest/migration-test -p /x86_64/migration/precopy/tcp/plain
> 
> Signed-off-by: Fabiano Rosas <farosas@suse.de>
> ---
>  tests/qtest/migration-test.c | 19 +++++++++++++++++--
>  1 file changed, 17 insertions(+), 2 deletions(-)
> 
> diff --git a/tests/qtest/migration-test.c b/tests/qtest/migration-test.c
> index 2253e0fc5b..35bb224d18 100644
> --- a/tests/qtest/migration-test.c
> +++ b/tests/qtest/migration-test.c
> @@ -71,6 +71,13 @@ static QTestMigrationState dst_state;
>  #define QEMU_ENV_SRC "QTEST_QEMU_BINARY_SRC"
>  #define QEMU_ENV_DST "QTEST_QEMU_BINARY_DST"
>  
> +/*
> + * The tests using DEFAULT_DEVICES need a special invocation and
> + * cannot be reached from make check, so don't bother with the
> + * --without-default-devices build.

What's this "--without-default-devices"?

Other than this it looks all good.. thanks.

-- 
Peter Xu