On Tue, 10 Feb 2026, 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 <imammedo@redhat.com> Signed-off-by: Zhao Liu <zhao1.liu@intel.com> --- 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),
As this isn't strictly for user set maybe jusr call it OBJ_PROP_FLAG_EXTERNAL? (Can be set by external management application or global compat prop in later patches so user set is not quite right name,)