Re: [Qemu-devel] [PATCH 5/5] mc146818rtc: add "rtc" link to "/machine"

[Paolo Bonzini <pbonzini@redhat.com>]

Il 17/06/2014 19:09, Andreas Färber ha scritto:
> Do those management apps want a generic location for each machine or
> just for PC?

For machines that implement the RTC_CHANGE event.

> I know several ARM boards that have different ones on SoC
> and on PMIC (I2C) for instance. In that case it may be safer to
> implement an interface and to search for that?

Possibly, but I'm not sure how management can know which types have an 
interface.

If there are many clocks, they all *should* be based on rtc_clock and 
hopefully:

- either only one sends RTC_CHANGE events (right now only the PC's RTC 
sends the event)

- or the OS sets them to the same value when it modifies them, so they 
should have the same date property (but if not, one is as good as any 
other for the purpose of reconstructing lost RTC_CHANGE events).

> Or at least give the
> "rtc" node a more generic property type for ABI stability? I.e. you only
> want "date" here, not any other properties of the mc146818rtc.

The idea is to make a few selected properties "well-known" and link to 
them via aliases, in this case "date" from "/machine/rtc" is the 
well-known property.

Paolo