Re: [PATCH] Make virtio_net support carrier detection

[David Miller <davem@davemloft.net>]

From: Rusty Russell <rusty@rustcorp.com.au>
Date: Fri, 13 Mar 2009 10:17:11 +1030

> Subject: virtio_net: set carrier on by default.
> 
> Impact: fix carrier detection, older NetworkManager
> 
> This is actually two fixes:
> 1) If the virtio_net device doesn't support carrier, the answer is
>    "yes".  This is because before the status feature there was no way
>    of turning the link off in any host implementation, and it also helps
>    (older) NetworkManager versions to see the device.
> 
> 2) We should start with carrier on: virtnet_update_status() does nothing
>    if the status hasn't changed (ie. doesn't call netif_carrier_on()).
> 
> Reported-by: Pantelis Koukousoulas <pktoss@gmail.com>
> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

You can set netif_carrier_on() until you are blue in the face,
but until you hook up the ethtool link indication operation
NetworkManager won't see it.

I don't understand what all of this hob-knobbing is about,
Pantelis's patch was perfect, appropriate, and should have
gone straight in to net-2.6 and probably -stable too.

Is this some kind of control issue Rusty?  It's the only
explanation I can come up with :-))