Re: [PATCH v2 2/2] qmp: Expose MachineClass::default_ram_id

[Igor Mammedov <imammedo@redhat.com>]

On Tue, 26 May 2020 10:25:35 +0200
Michal Privoznik <mprivozn@redhat.com> wrote:

> If a management application (like Libvirt) want's to preserve
> migration ability and switch to '-machine memory-backend' it
> needs to set exactly the same RAM id as QEMU would. Since the id
> is machine type dependant, expose it under 'query-machines'
> result. Some machine types don't have the attribute set (riscv
> family for example), therefore the QMP attribute must be
> optional.
> 
> Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
> ---
>  hw/core/machine-qmp-cmds.c | 4 ++++
>  qapi/machine.json          | 5 ++++-
>  2 files changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/core/machine-qmp-cmds.c b/hw/core/machine-qmp-cmds.c
> index 2c5da8413d..3e11a740c9 100644
> --- a/hw/core/machine-qmp-cmds.c
> +++ b/hw/core/machine-qmp-cmds.c
> @@ -238,6 +238,10 @@ MachineInfoList *qmp_query_machines(Error **errp)
>              info->default_cpu_type = g_strdup(mc->default_cpu_type);
>              info->has_default_cpu_type = true;
>          }
> +        if (mc->default_ram_id) {
> +            info->default_ram_id = g_strdup(mc->default_ram_id);
> +            info->has_default_ram_id = true;
> +        }
>  
>          entry = g_malloc0(sizeof(*entry));
>          entry->value = info;
> diff --git a/qapi/machine.json b/qapi/machine.json
> index 39caa1d914..76c1606390 100644
> --- a/qapi/machine.json
> +++ b/qapi/machine.json
> @@ -355,13 +355,16 @@
>  # @default-cpu-type: default CPU model typename if none is requested via
>  #                    the -cpu argument. (since 4.2)
>  #
> +# @default-ram-id: the default ID of initial RAM memory backend (since 5.1)
> +#
>  # Since: 1.2.0
>  ##
>  { 'struct': 'MachineInfo',
>    'data': { 'name': 'str', '*alias': 'str',
>              '*is-default': 'bool', 'cpu-max': 'int',
>              'hotpluggable-cpus': 'bool',  'numa-mem-supported': 'bool',
> -            'deprecated': 'bool', '*default-cpu-type': 'str' } }
> +            'deprecated': 'bool', '*default-cpu-type': 'str',
> +            '*default-ram-id': 'str' } }
>  
>  ##
>  # @query-machines: