Re: QEMU Community Call Agenda Items (April 30th, 2024)

[Peter Maydell]

On Tue, 30 Apr 2024 at 08:36, Markus Armbruster <armbru@redhat.com> wrote:
>
> Daniel P. Berrangé <berrange@redhat.com> writes:
> >  * /machine to get the rtc-time property value
>
> This is an alias to the RTC device's "rtc-time" property.  Only some
> machines define it.  Useful because the actual property depends on
> machine type and configuration.  For q35, it's
> /machine/unattached/device[N]/rtc/date, where N can vary.
>
> If we moved the southbridge out of the /machine/unattached dump, we'd
> have something like /machine/q35/ich9-lpc/rtc/date.  Stable, but you
> have to know the machine type to find it.

Do we really want to call that stable, though? If we ever
wanted to refactor the devices internally it might change.

My gut feeling is that exposing something we want to
be stable as a specific "this is obviously an externally
exposed identifier" (e.g. in the way we do by having an
rtc-time property alias on the machine object) is more
likely to be reliable than trusting that a QOM path all
the way down to a specific device is never going to be
rearranged.

thanks
-- PMM