incompatibility of netfront driver with bonding module

[Yosuke Iwamatsu <y-iwamatsu@ab.jp.nec.com>]

Masroor Vettuparambil wrote:
> Thanks for your work.
> I could manage the live migration using a simple check in netfront while
> resuming on destination.
> 
> if (!(netdev->flags & IFF_SLAVE))
> 	memcpy(netdev->dev_addr, info->mac, ETH_ALEN);
> But this will work only if the interface is enslaved.
> 
> In your patch, should we let to change the MAC while interface is up?

It might be desirable, but I don't know for now if we can achieve it
easily.

> I need to include the support for arp link monitoring to netfront.

Is link monitoring really necessary?
If you mean you use link monitoring to change the active slave of the 
bond0, I think we can do that using ifenslave command inside domU.
  #ifenslave bond0 eth1     -> enslave new netif(eth1) to bonding device
  #ifenslave -d bond0 eth0  -> release old netif(eth0) from bonding

Regards,
   Yosuke

> 
> Regards
> Masroor,
>  
> 
> -----Original Message-----
> From: Yosuke Iwamatsu [mailto:y-iwamatsu@ab.jp.nec.com] 
> Sent: Thursday, April 03, 2008 12:00 PM
> To: Masroor Vettuparambil
> Cc: xen-devel@lists.xensource.com
> Subject: incompatibility of netfront driver with bonding module
> 
> Hi,
> 
> Masroor Vettuparambil wrote:
>> 1. Normally, bonding will inherit the mac from the first slave and 
>> assign it to all the other slaves added later. So the mac of vif will 
>> be updated. But during migration, the mac of vif is getting updated 
>> from xenstore(/vm/). So how about having a set_mac_address entry in 
>> netfront that update the xenstore?
> 
>> So I need help, especially on #1. Is it ok to update the xenstore /vm/
> 
>> keys from domU? how to do this?
> 
> I tried a bit to find out the way to update /vm/ keys from frontend, but
> didn't succeed. Either way, I don't think it is a good idea to update
> the xenstore key of the vif mac address, because the original mac will
> be lost and we won't be able to reset it e.g. after the guest reboot.
> 
> So the attached patch adds set mac_address() support to netfront.
> It doesn't touch xenstore at all, but just preserves the modified mac
> address in netfront_info structure and keeps using it after migration.
> 
> Thanks,
> -----------------------
> Yosuke Iwamatsu
>          NEC Corporation