diff --git a/docs/devel/qom.rst b/docs/devel/qom.rst index 3e34b07c98..c9237950d0 100644 --- a/docs/devel/qom.rst +++ b/docs/devel/qom.rst @@ -1,3 +1,5 @@ +.. _qom: + =========================== The QEMU Object Model (QOM) =========================== diff --git a/docs/devel/style.rst b/docs/devel/style.rst index 5bc6f2f095..ac2ce42a2f 100644 --- a/docs/devel/style.rst +++ b/docs/devel/style.rst @@ -628,6 +628,43 @@ are still some caveats to beware of QEMU Specific Idioms ******************** +QEMU Object Model Declarations +============================== + +The QEMU Object Model (QOM) provides a framework for handling objects +in the base C language. The first declaration of a storage or class +structure should always be the parent and leave a visual space between +that declaration and the new code. It is also useful to separate +backing for properties (options driven by the user) and internal state +to make navigation easier. + +For a storage structure the first declaration should always be called +"parent_obj" and for a class structure the first member should always +be called "parent_class" as below: + +.. code-block:: c + + struct MyDeviceState { + DeviceState parent_obj; + + /* Properties */ + int prop_a; + char *prop_b; + /* Other stuff */ + int internal_state; + }; + + struct MyDeviceClass { + DeviceClass parent_class; + + void (*new_fn1)(void); + bool (*new_fn2)(CPUState *); + }; + +Note that there is no need to provide typedefs for QOM structures +since these are generated automatically by the QOM declaration macros. +See :ref:`qom` for more details. + Error handling and reporting ============================