[Xen-devel] Re: [PATCH] incompatibility of netfront driver with bonding module

[Yosuke Iwamatsu <y-iwamatsu@xxxxxxxxxxxxx>]

Thank you.

Now I'm curious if you really succeeded the live migration of
passthrough domains, using pci-hotplug and bonding.
(Currently I have one testing machine and can only try
local migration.)

-- Yosuke

Masroor Vettuparambil wrote:
> The attached patch provides the arp link monitoring support for
> netfront.
> Also it prevents setting the mac while the interface is up.
>
> Regards
> Masroor 
>
> -----Original Message-----
> From: Yosuke Iwamatsu [mailto:y-iwamatsu@xxxxxxxxxxxxx] 
> Sent: Monday, April 07, 2008 12:36 PM
> To: Masroor Vettuparambil
> Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
> Subject: incompatibility of netfront driver with bonding module
>
> 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@xxxxxxxxxxxxx]
> > Sent: Thursday, April 03, 2008 12:00 PM
> > To: Masroor Vettuparambil
> > Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
> > 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
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