Subject: Re: [Xen-devel] [RFC v2 4/4] xen-netback: skip IPv4 and IPv6 interfaces

From: Zoltan Kiss <[email-masked]>
Date: Mon, 17 Feb 2014 14:36:55 +0000

There is a valid scenario to put IP addresses on the backend VIFs:

http://wiki.xen.org/wiki/Xen_Networking#Routing

Also, the backend is not necessarily Dom0, you can connect twou guests 
with backend/frontend pairs.

Zoli

On 15/02/14 02:59, Luis R. Rodriguez wrote:
> From: "Luis R. Rodriguez" <[email-masked]>
>
> The xen-netback driver is used only to provide a backend
> interface for the frontend. The link is the only thing we
> use, and that is used internally for letting us know when the
> xen-netfront is ready, when it switches to XenbusStateConnected.
>
> Note that only when the both the xen-netfront and xen-netback
> are both in state XenbusStateConnected will xen-netback allow
> userspace on the host (backend) to bring up the interface. Enabling
> and disabling the interface will simply enable or disable NAPI
> respectively, and that's used for IRQ communication set up with
> the xen event channels.
>
> Cc: Paul Durrant <[email-masked]>
> Cc: Ian Campbell <[email-masked]>
> Cc: Wei Liu <[email-masked]>
> Cc: [email-masked]
> Cc: [email-masked]
> Signed-off-by: Luis R. Rodriguez <[email-masked]>
> ---
>   drivers/net/xen-netback/interface.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c
> index d380e3f..07e6fd2 100644
> --- a/drivers/net/xen-netback/interface.c
> +++ b/drivers/net/xen-netback/interface.c
> @@ -351,7 +351,7 @@ struct xenvif *xenvif_alloc(struct device *parent, domid_t domid,
>
>   	eth_hw_addr_random(dev);
>   	memcpy(dev->dev_addr, xen_oui, 3);
> -	dev->priv_flags |= IFF_BRIDGE_NON_ROOT;
> +	dev->priv_flags |= IFF_BRIDGE_NON_ROOT | IFF_SKIP_IP;
>   	netif_napi_add(dev, &vif->napi, xenvif_poll, XENVIF_NAPI_WEIGHT);
>
>   	netif_carrier_off(dev);
>