Re: [PATCH 08/16] qom: introduce object_register_sugar_prop

[Paolo Bonzini]

On 14/11/19 10:53, Marc-André Lureau wrote:
>>  include/qom/object.h |  1 +
>>  qom/object.c         | 23 +++++++++++++++++++++--
>>  vl.c                 | 10 +++-------
>>  3 files changed, 25 insertions(+), 9 deletions(-)
>>
>> diff --git a/include/qom/object.h b/include/qom/object.h
>> index 128d00c..230b18f 100644
>> --- a/include/qom/object.h
>> +++ b/include/qom/object.h
>> @@ -679,6 +679,7 @@ void object_apply_global_props(Object *obj, const 
>> GPtrArray *props,
>>                                 Error **errp);
>>  void object_set_machine_compat_props(GPtrArray *compat_props);
>>  void object_set_accelerator_compat_props(GPtrArray *compat_props);
>> +void object_register_sugar_prop(const char *driver, const char *prop, const 
>> char *value);
> 
> Or simply
> 
> void object_add_global_prop(const char *typename, ...) ?

This is actually how I called it first, but I didn't like it because
it's prioritized _below_ -global, and it's easy to confuse it with
object_add_global_prop.

>>  /*
>>   * Set machine's global property defaults to @compat_props.
>> @@ -445,7 +464,7 @@ void object_apply_compat_props(Object *obj)
>>
>>      for (i = 0; i < ARRAY_SIZE(object_compat_props); i++) {
>>          object_apply_global_props(obj, object_compat_props[i],
>> -                                  &error_abort);
>> +                                  i == 2 ? &error_fatal : &error_abort);
> 
> Isn't error_abort() appropriate in all cases?

Unfortunately not, because otherwise "-accel tcg,tb-size=foo" would crash.

>>      }
>>  }
>>
>> diff --git a/vl.c b/vl.c
>> index 843b263..cb993dd 100644
>> --- a/vl.c
>> +++ b/vl.c
>> @@ -896,13 +896,9 @@ static void configure_rtc(QemuOpts *opts)
>>      value = qemu_opt_get(opts, "driftfix");
>>      if (value) {
>>          if (!strcmp(value, "slew")) {
>> -            static GlobalProperty slew_lost_ticks = {
>> -                .driver   = "mc146818rtc",
>> -                .property = "lost_tick_policy",
>> -                .value    = "slew",
>> -            };
>> -
>> -            qdev_prop_register_global(&slew_lost_ticks);
>> +            object_register_sugar_prop("mc146818rtc",
>> +                                       "lost_tick_policy",
>> +                                       "slew");
> 
> Why do you convert this since it's a device?

Not strictly necessary, but it's more compact and it more or less
matches the usecase for this function.

Paolo