On Mon, Nov 18, 2024 at 05:13:28PM -0500, Peter Xu wrote:
> Currently, a device can be realized even before machine is created, but
> only in one of QEMU's qtest, test-global-qdev-props.c.
>
> Right now, the test_static_prop_subprocess() test (which creates one simple
> object without machine created) will internally make "/machine" to be a
> container, which may not be expected when developing the test.
>
> Now explicitly support that case when there's no real "/machine" object
> around, then unattached devices will be put under root ("/") rather than
> "/machine". Mostly only for this single test case, or for any future test
> cases when some device needs to be realized before the machine is present.
>
> This shouldn't affect anything else when QEMU runs as an emulator, as that
> always relies on a real machine being created before realizing any devices.
> It's because if "/machine" is wrongly created as a container, it'll fail
> QEMU very soon later on qemu_create_machine() trying to create the real
> machine, conflicting with the "/machine" container.
>
> Signed-off-by: Peter Xu <pet...@redhat.com>
> ---
> hw/core/qdev.c | 12 ++++++++++--
> 1 file changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/hw/core/qdev.c b/hw/core/qdev.c
> index 5f13111b77..eff297e584 100644
> --- a/hw/core/qdev.c
> +++ b/hw/core/qdev.c
> @@ -475,9 +475,17 @@ static void device_set_realized(Object *obj, bool value,
> Error **errp)
>
> if (!obj->parent) {
> gchar *name = g_strdup_printf("device[%d]", unattached_count++);
> + Object *root = qdev_get_machine();
>
> - object_property_add_child(container_get(qdev_get_machine(),
> - "/unattached"),
> + /*
> + * We could have qdev test cases trying to realize() a device
> + * without machine created. In that case we use the root.
> + */
> + if (!root) {
> + root = object_get_root();
> + }
IMHO modifying the qdev.c code to workaround limitations of the test suite
is not a nice approach. Even if it is more work, I'd say it is better to
properly stub a /machine object in the test case, so that it complies with
expectations of qdev.c
> +
> + object_property_add_child(container_get(root, "/unattached"),
> name, obj);
> unattached_parent = true;
> g_free(name);
With regards,
Daniel
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