Re: [PATCH v12 6/8] net/tap: support local migration with virtio-net

[Markus Armbruster <armbru@redhat.com>]

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

> Support transferring of TAP state (including open fd) through
> migration stream as part of viritio-net "local-migration".
>
> Add new option, incoming-fds, which should be set to true to
> trigger new logic.
>
> For new option require explicitly unset script and downscript,
> to keep possibility of implementing support for them in future.
>
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>

[...]

> diff --git a/qapi/net.json b/qapi/net.json
> index 118bd349651..79f5ce9f431 100644
> --- a/qapi/net.json
> +++ b/qapi/net.json
> @@ -355,6 +355,9 @@
>  # @poll-us: maximum number of microseconds that could be spent on busy
>  #     polling for tap (since 2.7)
>  #
> +# @incoming-fds: do not open/connnect any resources, instead wait for
> +#     TAP state from incoming migration stream.  (Since 11.0)

"resources"?  The name @incoming-fds suggests this is about file
descriptors...

"wait for TAP state from" does not make sense.  Do you mean "retrieve
TAP state from"?

Is any part of NetdevTapOptions ignored when @incoming-fds is true?

> +#
>  # Since: 1.2
>  ##
>  { 'struct': 'NetdevTapOptions',
> @@ -373,7 +376,8 @@
>      '*vhostfds':   'str',
>      '*vhostforce': 'bool',
>      '*queues':     'uint32',
> -    '*poll-us':    'uint32'} }
> +    '*poll-us':    'uint32',
> +    '*incoming-fds': 'bool' } }
>  
>  ##
>  # @NetdevSocketOptions: