Re: [libvirt] [PATCH v4 7/8] qmp: Support abstract classes on device-list-properties
(CCing libvirt people, as I forgot to CC them)
On Mon, Oct 31, 2016 at 03:07:23PM +0100, Igor Mammedov wrote:
On Fri, 28 Oct 2016 23:48:06 -0200
Eduardo Habkost <ehabkost(a)redhat.com> wrote:
> When an abstract class is used on device-list-properties, we can
> simply return the class properties registered for the class.
>
> This will be useful if management software needs to query for
> supported options that apply to all devices of a given type (e.g.
> options supported by all CPU models, options supported by all PCI
> devices).
Patch looks fine to me but I'm not qmp interface guru
so I'd leave review up to maintainers.
One question though,
How would management software discover typename of abstract class?
It depends on the use case. On some cases, management may already
have bus-specific logic that will know what's the base type it
needs to query (e.g. it may query "pci-device" to find out if all
PCI devices support a given option). On other cases, it may be
discovered using other commands.
For the CPU case, I will propose adding the base QOM CPU typename
in the query-target command.
Perhaps this patch should be part of some other series.
This is a valid point. In this case, it depends on the approach
we want to take: do we want to provide a flexible interface for
management, let them find ways to make it useful and give us
feedback on what is lacking; or do we want to provide the new
interface only after we have specified the complete solution for
the problem?
I don't know the answer. I will let the qdev/QOM/QMP maintainers
answer that.
> Signed-off-by: Eduardo Habkost <ehabkost(a)redhat.com>
> ---
> Changes series v1 -> v2:
> * (none)
>
> Changes series v2 -> v3:
> * Reworded commit message
>
> Changes series v3 -> v4:
> * (none)
> ---
> qmp.c | 21 +++++++++------------
> 1 file changed, 9 insertions(+), 12 deletions(-)
>
> diff --git a/qmp.c b/qmp.c
> index a06cb7b..1e7e60d 100644
> --- a/qmp.c
> +++ b/qmp.c
> @@ -518,7 +518,7 @@ DevicePropertyInfoList *qmp_device_list_properties(const char
*typename,
> Error **errp)
> {
> ObjectClass *klass;
> - Object *obj;
> + Object *obj = NULL;
> ObjectProperty *prop;
> ObjectPropertyIterator iter;
> DevicePropertyInfoList *prop_list = NULL;
> @@ -537,19 +537,16 @@ DevicePropertyInfoList *qmp_device_list_properties(const char
*typename,
> }
>
> if (object_class_is_abstract(klass)) {
> - error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "name",
> - "non-abstract device type");
> - return NULL;
> - }
> -
> - if (DEVICE_CLASS(klass)->cannot_destroy_with_object_finalize_yet) {
> - error_setg(errp, "Can't list properties of device
'%s'", typename);
> - return NULL;
> + object_class_property_iter_init(&iter, klass);
> + } else {
> + if (DEVICE_CLASS(klass)->cannot_destroy_with_object_finalize_yet) {
> + error_setg(errp, "Can't list properties of device
'%s'", typename);
> + return NULL;
> + }
> + obj = object_new(typename);
> + object_property_iter_init(&iter, obj);
> }
>
> - obj = object_new(typename);
> -
> - object_property_iter_init(&iter, obj);
> while ((prop = object_property_iter_next(&iter))) {
> DevicePropertyInfo *info;
> DevicePropertyInfoList *entry;
--
Eduardo