On Tue, Feb 10, 2026 at 09:49:40AM +0000, Daniel P. Berrangé wrote: > On Tue, Feb 10, 2026 at 11:23:34AM +0800, Zhao Liu wrote: > > Introduce three new flags to `ObjectPropertyFlags` to better manage > > property interactions with external users (CLI, QMP, HMP): > > > > 1. OBJ_PROP_FLAG_USER_SET: > > Marks a property as having been modified by an external user. > > > > This flag is designed to be "sticky": once set, it persists even if > > the property value is subsequently overwritten by internal logic. > > It allows the QEMU system to distinguish user intent. > > > > The advantage of this design is that it is not needed to manually > > clear the USER_SET flag on every internal write. This simplifies the > > logic and decouples flag management from the current property setting > > path (object_property_set()). > > > > This is chosen over a strict "current origin" approach (where > > internal writes would clear the flag) for a practical reason: QEMU > > code often modifies underlying struct fields (which are defined as > > properties) directly, bypassing the property API entirely. This makes > > it impossible to "accurately" track whether the *current* value truly > > comes from the user. Therefore, a sticky "user touched this" flag is > > the only meaningful and robust solution. > > > > 2. OBJ_PROP_FLAG_DEPRECATED: > > Marks a property as deprecated. > > > > 3. OBJ_PROP_FLAG_INTERNAL: > > Marks a property as internal-only, disallowing external user access. > > > > Additionally, update object_property_set_flags() to implement the > > enforcement logic. When a property is flagged with > > OBJ_PROP_FLAG_USER_SET: > > - If the property is also marked OBJ_PROP_FLAG_DEPRECATED, report a > > warning. > > - If the property is also marked OBJ_PROP_FLAG_INTERNAL, raise an error > > and stop the operation. > > > > Suggested-by: Igor Mammedov <[email protected]> > > Signed-off-by: Zhao Liu <[email protected]> > > --- > > include/qom/object.h | 24 ++++++++++++++++++++++++ > > qom/object.c | 15 +++++++++++++++ > > 2 files changed, 39 insertions(+) > > > > diff --git a/include/qom/object.h b/include/qom/object.h > > index 856b12e7289c..1b77429aa28b 100644 > > --- a/include/qom/object.h > > +++ b/include/qom/object.h > > @@ -109,6 +109,30 @@ typedef enum { > > * will automatically add a getter and a setter to this property. > > */ > > OBJ_PROP_FLAG_READWRITE = (OBJ_PROP_FLAG_READ | OBJ_PROP_FLAG_WRITE), > > + /* > > + * The property was explicitly set by an external user. > > + * > > + * This flag is set whenever the property is modified via external > > interfaces > > + * (CLI, QMP, HMP). It allows internal code to distinguish whether the > > + * property has been modified by the user. > > + * > > + * Once set, this flag persists even if the property value is > > subsequently > > + * overwritten by internal logic. It is NOT automatically cleared and > > must > > + * be explicitly cleared using object_property_clear_flags(). > > + */ > > + OBJ_PROP_FLAG_USER_SET = BIT(2), > > + /* > > + * The property is deprecated and will be removed in the future > > version. > > + * > > + * Any setting to this property by the user will raise a deprecation > > warning. > > + */ > > + OBJ_PROP_FLAG_DEPRECATED = BIT(3), > > + /* > > + * The property is internal only and cannot be set by the user. > > + * > > + * Any setting to this property by the user will raise an error. > > + */ > > + OBJ_PROP_FLAG_INTERNAL = BIT(4), > > } ObjectPropertyFlags; > > I don't think this single enum design is very desirable, as it is mixing up > pieces of information with three distinct lifetimes / scopes. > > The OBJ_PROP_FLAD_{READ,WRITE,READWRITE} values are scoped to the execution > of the property adder methods. > > The OBJ_PROP_FLAG_{DEPRECATED,INTERNAL} values are scoped to the lifetime > of the class. > > The OBJ_PROP_FLAG_USER_SET value is scoped to the lifetime of the instance.
In fact, with my comment on the later patch, OBJ_PROP_FLAG_DEPRECATED should not be modelled as a boolean flag at all. We need to record a const char* deprecation_note internally, so that warn_report can provide useful info to the user. We can turn that into a "bool deprecated" flag in the QAPI command response for querying properties. 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 :|
