[email protected] writes:
> From: Marc-André Lureau <[email protected]>
>
> The link properties are not printed in "info qtree", I don't know if
> this was intentional. We currently register legacy properties for
> link/ptr properties, but they don't have PropertyInfo getters (only
> ObjectPropertyAccessor, when using non-legacy properties)
>
> By not registering a (unusable?) legacy property, "info qtree" can now
> print the link.
>
> Signed-off-by: Marc-André Lureau <[email protected]>
> ---
> hw/core/qdev-properties.c | 5 ++---
> 1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/hw/core/qdev-properties.c b/hw/core/qdev-properties.c
> index b7e8a89ba5..fe260a9670 100644
> --- a/hw/core/qdev-properties.c
> +++ b/hw/core/qdev-properties.c
> @@ -1143,14 +1143,13 @@ static void
> qdev_class_add_legacy_property(DeviceClass *dc, const Property *prop
> {
> g_autofree char *name = NULL;
>
> - /* Register pointer properties as legacy properties */
> - if (!prop->info->print && prop->info->get) {
> + if (!prop->info->print) {
> return;
> }
>
> name = g_strdup_printf("legacy-%s", prop->name);
> object_class_property_add(OBJECT_CLASS(dc), name, "str",
> - prop->info->print ? qdev_get_legacy_property : prop->info->get,
> + qdev_get_legacy_property,
> NULL, NULL, (Property *)prop);
> }
The old code confuses me. Let's go through it real slow.
/**
* qdev_class_add_legacy_property:
* @dev: Device to add the property to.
* @prop: The qdev property definition.
*
* Add a legacy QOM property to @dev for qdev property @prop.
*
* Legacy properties are string versions of QOM properties. The format of
* the string depends on the property type. Legacy properties are only
* needed for "info qtree".
*
* Do not use this in new code! QOM Properties added through this interface
* will be given names in the "legacy" namespace.
*/
static void qdev_class_add_legacy_property(DeviceClass *dc, const Property
*prop)
{
g_autofree char *name = NULL;
/* Register pointer properties as legacy properties */
The comment talks about "pointer properties". We used to call
properties defined with DEFINE_PROP_PTR() that way, but these were
deleted years ago. The comment is even older. I'm going to ignore it.
if (!prop->info->print && prop->info->get) {
return;
}
To get here, prop->info->print || !prop->info->get.
name = g_strdup_printf("legacy-%s", prop->name);
object_class_property_add(OBJECT_CLASS(dc), name, "str",
prop->info->print ? qdev_get_legacy_property : prop->info->get,
NULL, NULL, (Property *)prop);
If qdev property @prop has a .print() method, we create a QOM property
"legacy-FOO" of type "str" with qdev_get_legacy_property() as .get(),
and no .set() or .release().
qdev_get_legacy_property() is a QOM .get() wrapping around qdev
.print(): it calls .print() to format the property value as a string
(arbitrarily limited to 1023 characters), then visits it with
visit_type_str().
Aside: there seems to be just one property that implements .print():
DEFINE_PROP_PCI_DEVFN(), in qdev_prop_pci_devfn. Quite a lot of
infrastructure just for that.
Else, prop->info->get is null, because prop->info->print || !prop->info->get.
So we create a QOM property "legacy-FOO" with no .get(), .set(),
.release(). Why?
Your patch gets rid of these. How does this make "info qtree" show link
properties? Hmm... qdev_print_props() uses "legacy-FOO" instead of
"FOO" when it exists. But a "legacy-FOO" without a .get() will fail.
When it does, the property is skipped.
Is this what makes the patch work?
}
