Re: [Qemu-devel] [PATCH 1/3] qapi: Report support for -device cpu hotplug in query-machines

[David Gibson]

On Thu, 23 Jun 2016 22:23:23 +0200
Peter Krempa <address@hidden> wrote:

> For management apps it's very useful to know whether the selected
> machine type supports cpu hotplug via the new -device approach. Using
> the presence of 'query-hotpluggable-cpus' is enough for a withess.
> 
> Add a property to 'MachineInfo' called 'hotpluggable-cpus' that will
> report the presence of this feature.
> 
> Example of output:
>     {
>         "hotpluggable-cpus": false,
>         "name": "mac99",
>         "cpu-max": 1
>     },
>     {
>         "hotpluggable-cpus": true,
>         "name": "pseries-2.7",
>         "is-default": true,
>         "cpu-max": 255,
>         "alias": "pseries"
>     },

I'd been under the impression that there was a general way of detecting
the availability of a particular qmp command.  Was I mistaken?

> Signed-off-by: Peter Krempa <address@hidden>
> ---
>  qapi-schema.json | 5 ++++-
>  vl.c             | 1 +
>  2 files changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/qapi-schema.json b/qapi-schema.json
> index 0964eec..24ede28 100644
> --- a/qapi-schema.json
> +++ b/qapi-schema.json
> @@ -2986,11 +2986,14 @@
>  # @cpu-max: maximum number of CPUs supported by the machine type
>  #           (since 1.5.0)
>  #
> +# @hotpluggable-cpus: cpu hotplug via -device is supported (since 2.7.0)
> +#
>  # Since: 1.2.0
>  ##
>  { 'struct': 'MachineInfo',
>    'data': { 'name': 'str', '*alias': 'str',
> -            '*is-default': 'bool', 'cpu-max': 'int' } }
> +            '*is-default': 'bool', 'cpu-max': 'int',
> +            'hotpluggable-cpus': 'bool'} }
> 
>  ##
>  # @query-machines:
> diff --git a/vl.c b/vl.c
> index c85833a..4c1f9ae 100644
> --- a/vl.c
> +++ b/vl.c
> @@ -1524,6 +1524,7 @@ MachineInfoList *qmp_query_machines(Error **errp)
> 
>          info->name = g_strdup(mc->name);
>          info->cpu_max = !mc->max_cpus ? 1 : mc->max_cpus;
> +        info->hotpluggable_cpus = !!mc->query_hotpluggable_cpus;
> 
>          entry = g_malloc0(sizeof(*entry));
>          entry->value = info;
> -- 
> 2.8.3
> 


-- 
David Gibson <address@hidden>
Senior Software Engineer, Virtualization, Red Hat

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