Re: [Qemu-devel] [PATCH v3 1/2] globals: Allow global properties to be optional

[Marc-André Lureau]

Hi

On Thu, Jan 10, 2019 at 10:05 PM Eduardo Habkost <address@hidden> wrote:
>
> Making some global properties optional will let us simplify
> compat code when a given property works on most (but not all)
> subclasses of a given type.
>
> Device types will be able to opt out from optional compat
> properties by simply not registering those properties.
>
> Signed-off-by: Eduardo Habkost <address@hidden>
> ---
> Changes v2 -> v3:
> * Don't ignore all errors, ignore property only if it doesn't
>   exist
>
> Changes v1 -> v2:
> * (new patch)
>
> Note: the "An error is fatal for non-hotplugged devices [...]"
> comment that appears in the diff scope is inaccurate, but I will
> fix that in a separate patch because I don't want this to get
> into the way of fixing the crash.
> ---
>  include/hw/qdev-core.h | 3 +++
>  qom/object.c           | 3 +++
>  2 files changed, 6 insertions(+)
>
> diff --git a/include/hw/qdev-core.h b/include/hw/qdev-core.h
> index bc014c1c9f..29874c8611 100644
> --- a/include/hw/qdev-core.h
> +++ b/include/hw/qdev-core.h
> @@ -250,6 +250,8 @@ struct PropertyInfo {
>  /**
>   * GlobalProperty:
>   * @used: Set to true if property was used when initializing a device.
> + * @optional: If set to true, GlobalProperty will be skipped without errors
> + *            if the property doesn't exist.
>   *
>   * An error is fatal for non-hotplugged devices, when the global is applied.
>   */
> @@ -258,6 +260,7 @@ typedef struct GlobalProperty {
>      const char *property;
>      const char *value;
>      bool used;
> +    bool optional;

with optional/skip_if_missing

Reviewed-by: Marc-André Lureau <address@hidden>

>  } GlobalProperty;
>
>  static inline void
> diff --git a/qom/object.c b/qom/object.c
> index 4e5226ca12..b8c732063b 100644
> --- a/qom/object.c
> +++ b/qom/object.c
> @@ -385,6 +385,9 @@ void object_apply_global_props(Object *obj, const 
> GPtrArray *props, Error **errp
>          if (object_dynamic_cast(obj, p->driver) == NULL) {
>              continue;
>          }
> +        if (p->optional && !object_property_find(obj, p->property, NULL)) {
> +            continue;
> +        }
>          p->used = true;
>          object_property_parse(obj, p->value, p->property, &err);
>          if (err != NULL) {
> --
> 2.18.0.rc1.1.g3f1ff2140
>