On Tue, Feb 10, 2026 at 11:23:27AM +0800, Zhao Liu wrote:
Hi,
This is the v2 trying to introduce property flags to detect user's property setting (from CLI/QMP/HMP). I dropped RFC tag since previous RFC v1 [1].
This says what the series is proposing, but IMHO what is more important here is explaining why this either desirable or appropriate to add as general facility in QOM. The idea that code should take different action for a given fixed value, based on whether the value was set by the user, or left on the default, makes me very uncomfortable. There have been a number of situations where something that was initially a boolean flag, actually needed to be a tri-state instead, to provide semantics like "On", "Off", "Auto". This "user set" flag could support such behaviour indirectly, but since "user set" is an internal concept we'd still be only exposing a boolean externally, while using a tri-state internally. That does not give the full flexibility of a tri-state, because internally if we wanted to have the default to be "yes", it offers no way for the mgmt app to put it back to "auto". For properties that are not booleans, it is much less obvious to me whether we actually need a distinct "not set" concept at all. So overall, at a conceptual level, I don't think that QOM should care about /how/ a value came to be set. It should have no direct awareness of the "user input", rather it just represents the configuration of the system at a given point in time, however that came to pass. With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|