[Qemu-devel] Re: [PATCH 1/4] Add 'set_link' monitor command

[Anthony Liguori <anthony@codemonkey.ws>]

Mark McLoughlin wrote:
> Add a monitor command to setting a given network device's link status
> to 'up' or 'down'.
>
> Allows simulation of network cable disconnect.
>
> Signed-off-by: Mark McLoughlin <markmc@redhat.com>
> ---
>  monitor.c |    1 +
>  net.c     |   41 ++++++++++++++++++++++++++++++++++++++++-
>  net.h     |    2 ++
>  3 files changed, 43 insertions(+), 1 deletions(-)
>
> diff --git a/monitor.c b/monitor.c
> index f142a87..ac74711 100644
> --- a/monitor.c
> +++ b/monitor.c
> @@ -1497,6 +1497,7 @@ static const term_cmd_t term_cmds[] = {
>        "value", "set maximum speed (in bytes) for migrations" },
>      { "balloon", "i", do_balloon,
>        "target", "request VM to change it's memory allocation (in MB)" },
> +    { "set_link", "iis", do_set_link, "vlan_id dev_idx [up|down]" },
>      { NULL, NULL, },
>  };
>   

This command seems reasonable to me but the dev_idx thing is a bit too 
hacky.

> +    for(vc = vlan->first_client; vc != NULL; vc = vc->next)
> +        if (i++ == device_idx)
> +            break;
>   

I think a better way would be to allow a user to specify an id for the 
nic that gets saved early on.  info nics should print the id and a 
default id should be assigned.  I think you could argue either way as to 
whether the ids should be vlan local or global.

I sort of think that making them global has a number of advantages.  You 
could also use a string to identify the nics globally, it's up to you.

Regards,

Anthony Liguori