Re: [PATCH v10 3/8] qapi: add backend-transfer migration parameter

[Markus Armbruster <armbru@redhat.com>]

Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru> writes:

> We are going to implement backend-transfer feature: some devices
> will be able to transfer their backend through migration stream
> for local migration through UNIX domain socket. For example,
> virtio-net will migrate its attached TAP netdev, with all its
> connected file descriptors.
>
> In this commit we introduce a migration parameter, which enables
> the feature, for supporting devices (no one at the moment).
>
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>

[...]

>  void qmp_migrate_set_parameters(MigrationParameters *params, Error **errp)
> diff --git a/qapi/migration.json b/qapi/migration.json
> index f925e5541b..cbe88f0c91 100644
> --- a/qapi/migration.json
> +++ b/qapi/migration.json
> @@ -828,7 +828,8 @@
>             'mode',
>             'zero-page-detection',
>             'direct-io',
> -           'cpr-exec-command'] }
> +           'cpr-exec-command',
> +           'backend-transfer'] }
>  
>  ##
>  # @migrate-set-parameters:
> @@ -1004,6 +1005,13 @@
>  #     is @cpr-exec.  The first list element is the program's filename,
>  #     the remainder its arguments.  (Since 10.2)
>  #
> +# @backend-transfer: Enable backend-transfer feature for devices that
> +#     supports it.  In general that means that backend state and its

support

> +#     file descriptors are passed to the destination in the migraton
> +#     channel (which must be a UNIX socket).  Individual devices
> +#     declare the support for backend-transfer by per-device
> +#     backend-transfer option.  (Since 11.0)
> +#
>  # Features:
>  #
>  # @unstable: Members @x-checkpoint-delay and
> @@ -1043,7 +1051,8 @@
>              '*mode': 'MigMode',
>              '*zero-page-detection': 'ZeroPageDetection',
>              '*direct-io': 'bool',
> -            '*cpr-exec-command': [ 'str' ]} }
> +            '*cpr-exec-command': [ 'str' ],
> +            '*backend-transfer': 'bool' } }
>  
>  ##
>  # @query-migrate-parameters:

With the grammar fix, QAPI schema
Acked-by: Markus Armbruster <armbru@redhat.com>