We are trying to understand what means "a qdev is realized".
One explanation was "the device is guest visible"; however
many devices are realized before being mapped, thus are not
"guest visible". Some devices map / wire their IRQs before
being realized (such ISA devices). There is a need for devices
to be "automatically" mapped/wired (see [2]) such CLI-created
devices, but this apply generically to dynamic machines.
Currently the device creation steps are expected to roughly be:
(external use) (QDev core) (Device Impl)
~~~~~~~~~~~~ ~~~~~~~~~ ~~~~~~~~~~~
INIT enter
----->
+----------------------+
| Allocate state |
+----------------------+
----->
+---------------------+
| INIT children |
| |
| Alias children properties
| |
| Expose properties |
INIT exit +---------------------+
<-----------------------------------
+----------------+
| set properties |
| |
| set ClkIn |
+----------------+ REALIZE enter
---------------------------------->
+----------------------+
| Use config properties|
| |
| Realize children |
| |
| Init GPIOs/IRQs |
| |
| Init MemoryRegions |
+----------------------+
REALIZE exit
<----------------------------------- ---- "realized" / "guest visible"
+-----------------+
| Explicit wiring:|
| IRQs |
| I/O / Mem |
| ClkOut |
+-----------------+ RESET enter
--------------------------------->
+----------------------+
| Reset default values |
+----------------------+
But as mentioned, various devices "wire" parts before they exit
the "realize" step.
In order to clarify, I'm trying to enforce what can be done
*before* and *after* realization.
*after* a device is expected to be stable (no more configurable)
and fully usable.
To be able to use internal/auto wiring (such ISA devices) and
keep the current external/explicit wiring, I propose to add an
extra "internal wiring" step, happening after the REALIZE step
as:
(external use) (QDev core) (Device Impl)
~~~~~~~~~~~~ ~~~~~~~~~ ~~~~~~~~~~~
INIT enter
----->
+----------------------+
| Allocate state |
+----------------------+
----->
+---------------------+
| INIT children |
| |
| Alias children properties
| |
| Expose properties |
INIT exit +---------------------+
<-----------------------------------
+----------------+
| set properties |
| |
| set ClkIn |
+----------------+ REALIZE enter
---------------------------------->
+----------------------+
| Use config properties|
| |
| Realize children |
| |
| Init GPIOs/IRQs |
| |
| Init MemoryRegions |
+----------------------+
REALIZE exit <---
+----------------------+
| Internal auto wiring |
| IRQs | (i.e. ISA bus)
| I/O / Mem |
| ClkOut |
+----------------------+
<--- ---- "realized"
+-----------------+
| External wiring:|
| IRQs |
| I/O / Mem |
| ClkOut |
+-----------------+ RESET enter ---- "guest visible"
--------------------------------->
+----------------------+
| Reset default values |
+----------------------+
The "realized" point is not changed. "guest visible" concept only
occurs *after* wiring, just before the reset phase.
This change introduces the DeviceClass::wire handler within qdev
core realization code.
Signed-off-by: Philippe Mathieu-Daudé <philmd@xxxxxxxxxx>
---
include/hw/qdev-core.h | 7 +++++++
hw/core/qdev.c | 20 +++++++++++++++++++-
2 files changed, 26 insertions(+), 1 deletion(-)
diff --git a/include/hw/qdev-core.h b/include/hw/qdev-core.h
index 530f3da7021..021bb7afdc0 100644
--- a/include/hw/qdev-core.h
+++ b/include/hw/qdev-core.h
@@ -102,7 +102,12 @@ typedef int (*DeviceSyncConfig)(DeviceState *dev, Error **errp);
* @props: Properties accessing state fields.
* @realize: Callback function invoked when the #DeviceState:realized
* property is changed to %true.
+ * @wire: Callback function called after @realize to connect IRQs,
+ * clocks and map memories. Can not fail.
+ * @unwire: Callback function to undo @wire. Called before @unrealize.
+ * Can not fail.
* @unrealize: Callback function invoked when the #DeviceState:realized
+ * property is changed to %false. Can not fail.
* property is changed to %false.
* @sync_config: Callback function invoked when QMP command device-sync-config
* is called. Should synchronize device configuration from host to guest part
@@ -171,6 +176,8 @@ struct DeviceClass {
*/
DeviceReset legacy_reset;
DeviceRealize realize;
+ void (*wire)(DeviceState *dev);
+ void (*unwire)(DeviceState *dev);
DeviceUnrealize unrealize;
DeviceSyncConfig sync_config;
diff --git a/hw/core/qdev.c b/hw/core/qdev.c
index 82bbdcb654e..38449255365 100644
--- a/hw/core/qdev.c
+++ b/hw/core/qdev.c
@@ -554,6 +554,15 @@ static void device_set_realized(Object *obj, bool value, Error **errp)
}
}
+ if (dc->wire) {
+ if (!dc->unwire) {
+ warn_report_once("wire() without unwire() for type '%s'",
+ object_get_typename(OBJECT(dev)));
+ }
+ dc->wire(dev);
+ }
+
+ /* At this point the device is "guest visible". */
qatomic_store_release(&dev->realized, value);
} else if (!value && dev->realized) {
@@ -573,6 +582,15 @@ static void device_set_realized(Object *obj, bool value, Error **errp)
*/
smp_wmb();
+ if (dc->unwire) {
+ if (!dc->wire) {
+ error_report("disconnect() without connect() for type '%s'",
+ object_get_typename(OBJECT(dev)));
+ abort();
+ }
+ dc->unwire(dev);
+ }
+
QLIST_FOREACH(bus, &dev->child_bus, sibling) {
qbus_unrealize(bus);
}
@@ -585,8 +603,8 @@ static void device_set_realized(Object *obj, bool value, Error **errp)
dev->pending_deleted_event = true;
DEVICE_LISTENER_CALL(unrealize, Reverse, dev);
}
-
assert(local_err == NULL);
+
return;
child_realize_fail:
--
2.47.1
