Re: [PATCH 10/11] vl: Enable JSON syntax for -device

[Eric Blake <eblake@redhat.com>]

On Fri, Sep 24, 2021 at 11:04:26AM +0200, Kevin Wolf wrote:
> Like we already do for -object, introduce support for JSON syntax in
> -device, which can be kept stable in the long term and guarantees that a
> single code path with identical behaviour is used for both QMP and the
> command line. Compared to the QemuOpts based code, the parser contains
> less surprises and has support for non-scalar options (lists and
> structs). Switching management tools to JSON means that we can more
> easily change the "human" CLI syntax from QemuOpts to the keyval parser
> later.
> 
> In the QAPI schema, a feature flag is added to the device-add command to
> allow management tools to detect support for this.
> 
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
>  qapi/qdev.json | 15 +++++++++----
>  softmmu/vl.c   | 58 ++++++++++++++++++++++++++++++++++++++++++++------
>  2 files changed, 62 insertions(+), 11 deletions(-)
> 
> diff --git a/qapi/qdev.json b/qapi/qdev.json
> index b83178220b..cdc8f911b5 100644
> --- a/qapi/qdev.json
> +++ b/qapi/qdev.json
> @@ -32,17 +32,23 @@
>  ##
>  # @device_add:
>  #
> +# Add a device.
> +#
>  # @driver: the name of the new device's driver
>  #
>  # @bus: the device's parent bus (device tree path)
>  #
>  # @id: the device's ID, must be unique
>  #
> -# Additional arguments depend on the type.
> -#
> -# Add a device.
> +# Features:
> +# @json-cli: If present, the "-device" command line option supports JSON
> +#            syntax with a structure identical to the arguments of this
> +#            command.
>  #
>  # Notes:
> +#
> +# Additional arguments depend on the type.
> +#
>  # 1. For detailed information about this command, please refer to the
>  #    'docs/qdev-device-use.txt' file.
>  #
> @@ -67,7 +73,8 @@
>  ##
>  { 'command': 'device_add',
>    'data': {'driver': 'str', '*bus': 'str', '*id': 'str'},
> -  'gen': false } # so we can get the additional arguments
> +  'gen': false, # so we can get the additional arguments
> +  'features': ['json-cli'] }

Eventually, we'll get rid of this 'gen':false, but this patch series
is already an improvement towards that goal.

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org