Re: [PATCH] net: vhost-user: add QAPI events to report connection state

[Laurent Vivier <lvivier@redhat.com>]

On 14/02/2025 11:06, Markus Armbruster wrote:
> Laurent Vivier <lvivier@redhat.com> writes:
> 
>> The netdev reports NETDEV_VHOST_USER_CONNECTED event when
>> the chardev is connected, and NETDEV_VHOST_USER_DISCONNECTED
>> when it is disconnected.
>>
>> The NETDEV_VHOST_USER_CONNECTED event includes the ChardevInfo
>> (label, filename and frontend_open).
>>
>> This allows a system manager like libvirt to detect when the server
>> fails.
>>
>> For instance with passt:
>>
>> { 'execute': 'qmp_capabilities' }
>> { "return": { } }
>>
>> [killing passt here]
>>
>> { "timestamp": { "seconds": 1739517243, "microseconds": 115081 },
>>    "event": "NETDEV_VHOST_USER_DISCONNECTED",
>>    "data": { "netdev-id": "netdev0" } }
>>
>> [automatic reconnection with reconnect-ms]
>>
>> { "timestamp": { "seconds": 1739517290, "microseconds": 343777 },
>>    "event": "NETDEV_VHOST_USER_CONNECTED",
>>    "data": { "netdev-id": "netdev0",
>>              "info": { "frontend-open": true,
>>                        "filename": "unix:",
>>                        "label": "chr0" } } }
>>
>> Signed-off-by: Laurent Vivier <lvivier@redhat.com>
> 
> Standard question for events: if a management application misses an
> event, say because it restarts and reconnects, is there a way to obtain
> the missed information with a query command?
> 

query-chardev could help but it doesn't provide the netdev id.

in HMP, "info network" has the information, but for QMP we had a try with a query-netdev 
in the past but the series has been reverted.

f9bb0c1f9862 ("Revert "qapi: net: Add query-netdev command"")
d32ad10a14d4 ("qapi: net: Add query-netdev command")

Thanks,
Laurent
Thanks
Laurent