Re: [Xen-devel] [PATCH 1/2] libxl: Add a version check of QEMU for QMP commands

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Tue, Mar 13, 2018 at 11:13:17AM +0000, Anthony PERARD wrote:
> On connection to QEMU via QMP, the version of QEMU is provided, store it
> for later use.
> 
> Add a function qmp_qemu_check_version that can be used to check if QEMU
> is new enough for certain fonctionnality. This will be used in a moment.
> 
> As it's a static function, it is commented out until first use, which is
> in the next patch.
> 
> Signed-off-by: Anthony PERARD <anthony.perard@xxxxxxxxxx>
> ---
>  tools/libxl/libxl_qmp.c | 31 ++++++++++++++++++++++++++++++-
>  1 file changed, 30 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/libxl/libxl_qmp.c b/tools/libxl/libxl_qmp.c
> index eab993aca9..b1c6598cf7 100644
> --- a/tools/libxl/libxl_qmp.c
> +++ b/tools/libxl/libxl_qmp.c
> @@ -75,6 +75,11 @@ struct libxl__qmp_handler {
>  
>      int last_id_used;
>      LIBXL_STAILQ_HEAD(callback_list, callback_id_pair) callback_list;
> +    struct {
> +        int major;
> +        int minor;
> +        int micro;
> +    } version;
>  };
>  
>  static int qmp_send(libxl__qmp_handler *qmp,
> @@ -296,9 +301,22 @@ static int qmp_handle_response(libxl__gc *gc, 
> libxl__qmp_handler *qmp,
>      LOGD(DEBUG, qmp->domid, "message type: %s", 
> libxl__qmp_message_type_to_string(type));
>  
>      switch (type) {
> -    case LIBXL__QMP_MESSAGE_TYPE_QMP:
> +    case LIBXL__QMP_MESSAGE_TYPE_QMP: {
> +        const libxl__json_object *o;
> +        o = libxl__json_map_get("QMP", resp, JSON_MAP);
> +        o = libxl__json_map_get("version", o, JSON_MAP);
> +        o = libxl__json_map_get("qemu", o, JSON_MAP);
> +        qmp->version.major = libxl__json_object_get_integer(
> +            libxl__json_map_get("major", o, JSON_INTEGER));
> +        qmp->version.minor = libxl__json_object_get_integer(
> +            libxl__json_map_get("minor", o, JSON_INTEGER));
> +        qmp->version.micro = libxl__json_object_get_integer(
> +            libxl__json_map_get("micro", o, JSON_INTEGER));
> +        LOGD(DEBUG, qmp->domid, "QEMU version: %d.%d.%d",
> +             qmp->version.major, qmp->version.minor, qmp->version.micro);
>          /* On the greeting message from the server, enable QMP capabilities 
> */
>          return enable_qmp_capabilities(qmp);
> +    }

Are those fields available in QMP in all the versions we care about?

If so, 

Acked-by: Wei Liu <wei.liu2@xxxxxxxxxx>

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