Re: [PATCH] mc146818rtc: add a way to generate RTC interrupts via QMP

["Philippe Mathieu-Daudé" <philmd@linaro.org>]

On 26/4/24 11:48, Philippe Mathieu-Daudé wrote:
> Hi Daniil, Markus,
> 
> On 26/4/24 10:39, Markus Armbruster wrote:
>> Daniil Tatianin <d-tatianin@yandex-team.ru> writes:
>>
>>> This can be used to force-synchronize the time in guest after a long
>>> stop-cont pause, which can be useful for serverless-type workload.
>>>
>>> Signed-off-by: Daniil Tatianin <d-tatianin@yandex-team.ru>
>>> ---
>>>   hw/rtc/mc146818rtc.c         | 15 +++++++++++++++
>>>   include/hw/rtc/mc146818rtc.h |  1 +
>>>   qapi/misc-target.json        | 16 ++++++++++++++++
>>>   3 files changed, 32 insertions(+)
>>>
>>> diff --git a/hw/rtc/mc146818rtc.c b/hw/rtc/mc146818rtc.c
>>> index f4c1869232..6980a78d5f 100644
>>> --- a/hw/rtc/mc146818rtc.c
>>> +++ b/hw/rtc/mc146818rtc.c
>>> @@ -116,6 +116,21 @@ void qmp_rtc_reset_reinjection(Error **errp)
>>>       }
>>>   }
>>> +void qmp_rtc_notify(Error **errp)
>>> +{
>>> +    MC146818RtcState *s;
>>> +
>>> +    /*
>>> +     * See:
>>> +     * 
>>> https://www.kernel.org/doc/Documentation/virtual/kvm/timekeeping.txt
>>> +     */
>>> +    QLIST_FOREACH(s, &rtc_devices, link) {
>>> +        s->cmos_data[RTC_REG_B] |= REG_B_UIE;
>>> +        s->cmos_data[RTC_REG_C] |= REG_C_IRQF | REG_C_UF;
>>> +        qemu_irq_raise(s->irq);
>>> +    }
>>> +}
>>> +
>>
>> Note for later: qmp_rtc_notify() works on all realized mc146818rtc
>> devices.  Other kinds of RTC devices are silently ignored.  Just like
>> qmp_rtc_reset_reinjection().
> 
> IMO to avoid any future ambiguity (in heterogeneous machines), this
> command must take a QOM device path (or a list of) and only notify
> those.

If you disagree, at least please rename the command/method using
"broadcast" for trailer.