Re: [PATCH RFC 4/4] rtc: Have event RTC_CHANGE identify the RTC by QOM path

[Cédric Le Goater]

On 2/22/22 14:06, Peter Maydell wrote:
> On Tue, 22 Feb 2022 at 12:56, Philippe Mathieu-Daudé
> <philippe.mathieu.daude@gmail.com> wrote:
> > On 22/2/22 13:02, Markus Armbruster wrote:
> > > Event RTC_CHANGE is "emitted when the guest changes the RTC time" (and
> > > the RTC supports the event).  What if there's more than one RTC?
> >
> > w.r.t. RTC, a machine having multiple RTC devices is silly...
>
> I don't think we have any examples in the tree currently, but
> I bet real hardware like that does exist: the most plausible
> thing would be a board where there's an RTC built into the SoC
> but the board designers put an external RTC on the board (perhaps
> because it was better/more accurate/easier to make battery-backed).

Yes. like Aspeed machines.

C.


> In fact, here's an old bug report from a user trying to get
> their Debian system to use the battery-backed RTC as the
> "real" one rather than the non-battery-backed RTC device
> that's also part of the arm board they're using:
> https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=785445
>
> -- PMM