Using dhclient on netmounted /

[Ferenc Wagner]

Michal Suchanek <hramrach at centrum.cz> writes:

> I am netbooting machines occasionally and noticed that this works very
> poorly with dhclient (version 3 and 4).
>
> I use scripts from my Linux distributions which configure the network
> in initramfs using ipconfig. This somewhat works so long as dhclient
> is never run on the system.
>
> However, I added a new way to mount the image which contains the /
> filesystem and forgot to disable dhclient in that case.
>
> There are mutiple observed issues
>
>  - at the point when dhclient is started the system locks up for half
> a minute or so
>  - with dhclient 3 I also observed the system locking up completely
>  - with dhclient 3 the system fails to boot if the image server was
> not located in the same IP subnet (not tested with dhclient 4)
>
> The issues are caused by dhclient running scripts while the network is
> down which obviously breaks stuff if the scripts and anything else is
> locates on a net-mounted filesystem.
>
> Not running dhclient causes the lease not renewing, obviously.
>
> Generally dhclient seems quite incompatible with network booted
> systems. Is this intentional and should I purge dhclient from such
> systems and look alsewhere for a dhcp client implementation that works
> for network booted systems or is this a bug?

You may want to look up in the archives the thread I started here on
19th of April with the subject "How to not break nfsroot".  It didn't
elect much interest, but skipping the PREINIT phase via a short hook
made the freezes go away.  I also export the lease from the initramfs,
so discovery does not happen again.
-- 
Cheers,
Feri.