Re: [PATCH v15 2/6] qmp: add QMP command x-query-virtio-status

[Markus Armbruster <armbru@redhat.com>]

Philippe Mathieu-Daudé <philmd@linaro.org> writes:

[...]

> When a structure is only used by an unstable command, is it considered
> unstable too? IOW is it OK to modify it?

Yes.

docs/devel/qapi-code-gen.rst:

    Special features
    ~~~~~~~~~~~~~~~~

    [...]

    Feature "unstable" marks a command, event, enum value, or struct
    member as unstable.  It is not supported elsewhere so far.  Interfaces
    so marked may be withdrawn or changed incompatibly in future releases.

We support "unstable" exactly where we need it to mark parts of the
external interface unstable:

* Commands and events, because these *are* the external interface.

* Struct members, because they can be arguments / results of commands /
  events.

* Enum values, because these can be values of arguments / results.

* Not types.  Not needed, and would enable inconsistencies, like stable
  member with an unstable type.

Questions?

[...]