Re: Netboot fails with multiple interfaces, wireless

[Seewer Philippe <philippe.seewer-omB+W0Dpw2o@public.gmane.org>]

Warren Togami wrote:
> Harald,
> 
> I tried your root=dhcp netboot code.
> 
> Is it intended that you need both root=dhcp and ip=dhcp?  Surely the 
> first implies the second?

I guess a simple patch could set ip=dhcp if root=dhcp is supplied...

> 
> So it does successfully mount and NFS root boot, but as I feared it has 
> trouble due to the presence of a wireless device.  One thin client I 
> have is Intel Atom with e1000e NIC and iwlagn wireless.  It appears to 
> dhcp once successfully on the eth0 ethernet, but its event-driven nature 
> also tries to launch dhclient again on the wlan0.  dhclient complains 
> that dhclient is already running and fails.

That's weird it shouldn't do that, since dhclient is started with an 
interface option.

> dhclient wouldn't have succeeded at all on the iwlagn interface because 
> the firmware is lacking from the initrd, and it isn't associated.  Also 
> I don't see when it is ever desired to netboot over a wireless interface.
> 
> As for excluding wireless interfaces, we should do a few things:
> - Do not copy wireless drivers into the initrd.  You suggested using 
> /etc/modprobe.d/something.conf to blacklist the driver from loading.  We 
> would need a way to blacklist the driver during the initrd without 
> blacklisting it on the host system where the initrd is generated.  How?
> - Perhaps we should exclude any interfaces named "wlan*" from ifup and 
> dhclient.  This works for most devices, but some wireless drivers call 
> the wireless interfaces "eth*".
> - I have no idea if it is attempting to ifup and dhclient other devices 
> that appear like wmaster0.

I agree there. Wireless drivers shouldn't be included (yet). As for 
separating ethernet from wireless drivers, why not use 'nm' and 
disregard those drivers that contain 'ieee802011_register_hw'?

> 
> A separate but related matter is what to do if a machine has more than 
> one ethernet interface.  It seems the only sane thing you CAN do is ifup 
> and dhclient only on the first interface?

That depends on your definition of sane. See the nfs/networking patches 
I sent in march. They're be able to handle all kinds of weird combinations.

Regards,
Philippe
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