NFS/dhcp/tftp on eth1, kernel search NFS it on eth0

[Thomas Neumann]

Jean Spirat schrieb:
>>  All my tests works well but i have a failure when i try to install a 
>> host with two ethernet cards. The dhcp and tftp runs on the eth1 
>> network and it works fine. But the issue is that the fai kernel when 
>> loaded bring not eth1 but eth0.
>>
>> [...]
> to add a little more explanation:
>
> - host boot ok
> - pxe boot get the ip from the dhcp
> - tftp load the kernel ok
> - kernel fail to get the NFS server as it brings only eth0 up
I encountered the same with VMs provided by XenServer. As soon as I add 
a second interface, the newly added interface is enumerated as the first 
one ('eth0') and the previously existing interface is now the second one 
('eth1'). Which is not that much of a problem when the VM has been 
installed. udev figures out the correct order.

However it's quite a hassle when providing a new VM (or reinstalling an 
existing one), because the VM will boot from the wrong interface. I 
found 2 workarounds, but neither are pretty.

1.) create VM with one interface, install it, add the second one
  works for the installing, but remember to delete and create the second 
interface before/after re-installation
2.) if the VM is going to have 2 interfaces then create them in swapped 
order.
  works fine with installation and reinstallation.
  Flaws:  - Fortunately we didn't have to provide a VM with 3 or more 
interfaces yet
          -  Adding an interface to an already existing VM is a bit 
tricky, because I have to not only add it, but also remember to swap them.

Xen(Server) specific:
There's a hidden parameter device id, which you can't influence from the 
gui. We are in the process of provisioning VMs from the command line 
automatically. With the command line one is able to influence this 
parameter. Maybe this would be enough to guaranteeing the 
'FAI'-interface to be the 'first' one.

But a more general fix would be appreciated.

tschüß
thomas