[libvirt] [Qemu-devel] [PATCH 5/5] query-command-line-options: return help message for legacy options

[Markus Armbruster]

[Note cc: Eric]

Amos Kong <akong at redhat.com> writes:

> Some legacy options that have arguments weren't added to
> vm_config_groups[], so query-command-line-options returns a
> NULL parameters infolist. This patch try to return help message
> for this kind of legacy options.
>
> Example:
>  {
>      "helpmsg": "\"-vnc display    start a VNC server on display\\n\"",
>      "parameters": [
>      ],
>      "option": "vnc"
>  },

Do we have prospective users for this feature?

> Signed-off-by: Amos Kong <akong at redhat.com>
> ---
>  qapi-schema.json   | 5 ++++-
>  util/qemu-config.c | 3 +++
>  2 files changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/qapi-schema.json b/qapi-schema.json
> index 05ced9d..b3e6f46 100644
> --- a/qapi-schema.json
> +++ b/qapi-schema.json
> @@ -3943,13 +3943,16 @@
>  # Details about a command line option, including its list of parameter details
>  #
>  # @option: option name
> +# @helpmsg: help message for legacy options
>  #
>  # @parameters: an array of @CommandLineParameterInfo
>  #
>  # Since 1.5
>  ##
>  { 'type': 'CommandLineOptionInfo',
> -  'data': { 'option': 'str', 'parameters': ['CommandLineParameterInfo'] } }
> +  'data': { 'option': 'str',
> +            '*parameters': ['CommandLineParameterInfo'],
> +            '*helpmsg': 'str' } }
>  
>  ##
>  # @query-command-line-options:

Aha, here's the schema change missing in PATCH 3/5.

The schema needs to cover these kinds of options:

1. No argument

   { 'option': OPT-NAME }

2. QemuOpts argument

2a. with known parameters (QemuOptsList member desc[] not empty)

   { 'option': OPT-NAME,
     'parameters': [ { 'name': PAR-NAME, 'type': PAR-TYPE }, ... ] }

2b. with unknown parameters (desc[] empty)

   { 'option': OPT-NAME, parameters: [] }

3. Other argument

   { 'option': OPT-NAME, ? }

This patch adds 3.  We need to decide what we want there.

Any particular reason why we have to invent something new, and can't
simply fold it into 2b?

Note that I completely left out help strings, both on the option and on
the parameter level.  Both for brevity of presentation, and because I'd
like to see a use before we add them.

> diff --git a/util/qemu-config.c b/util/qemu-config.c
> index de233d8..a2def03 100644
> --- a/util/qemu-config.c
> +++ b/util/qemu-config.c
> @@ -176,6 +176,9 @@ CommandLineOptionInfoList *qmp_query_command_line_options(bool has_option,
>              } else if (idx >= 0) {
>                  info->parameters =
>                      get_param_infolist(vm_config_groups[idx]->desc);
> +            } else if (info->has_parameters) {
> +                info->has_helpmsg = true;
> +                info->helpmsg = g_strdup(option_helpmsgs[i]);
>              }
>  
>              entry = g_malloc0(sizeof(*entry));