Re: [RFC PATCH 1/4] qom: Introduce TypeInfo::registerable() callback

[Pierrick Bouvier <pierrick.bouvier@linaro.org>]

On 3/5/25 08:12, Philippe Mathieu-Daudé wrote:
> Introduce the TypeInfo::registerable() callback to allow
> runtime decision on whether register a QOM type or not.
> 
> Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
> ---
>   include/qom/object.h | 1 +
>   qom/object.c         | 4 ++++
>   qom/trace-events     | 1 +
>   3 files changed, 6 insertions(+)
> 
> diff --git a/include/qom/object.h b/include/qom/object.h
> index 9192265db76..f046791f60c 100644
> --- a/include/qom/object.h
> +++ b/include/qom/object.h
> @@ -476,6 +476,7 @@ struct TypeInfo
>   {
>       const char *name;
>       const char *parent;
> +    bool (*registerable)(void);
>   
>       size_t instance_size;
>       size_t instance_align;
> diff --git a/qom/object.c b/qom/object.c
> index 01618d06bd8..c62b7fd1695 100644
> --- a/qom/object.c
> +++ b/qom/object.c
> @@ -168,6 +168,10 @@ static TypeImpl *type_register_internal(const TypeInfo *info)
>           fprintf(stderr, "Registering '%s' with illegal type name\n", info->name);
>           abort();
>       }
> +    if (info->registerable && !info->registerable()) {
> +        trace_object_register_skipped(info->name);
> +        return NULL;
> +    }
>   
>       ti = type_new(info);
>   
> diff --git a/qom/trace-events b/qom/trace-events
> index b2e9f4a7127..29af95d8507 100644
> --- a/qom/trace-events
> +++ b/qom/trace-events
> @@ -3,3 +3,4 @@
>   # object.c
>   object_dynamic_cast_assert(const char *type, const char *target, const char *file, int line, const char *func) "%s->%s (%s:%d:%s)"
>   object_class_dynamic_cast_assert(const char *type, const char *target, const char *file, int line, const char *func) "%s->%s (%s:%d:%s)"
> +object_register_skipped(const char *type) "Not registering '%s' type"

That's a good way to be able to select at runtime the objects enabled, 
even though we'll have a binary with all qom objects code present.

Reviewed-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>