[PATCH] discover: implement a periodic requery for network devices

[Jeremy Kerr]

Hi all,

> If we boot a machine before external (network) dependencies are properly
> configured, it will have tried once to download configuration, and
> possibly failed due to that configuration not being present.
> 
> This change introduces a periodic requery of network resources. After a
> timeout, petitboot will either re-acquire its DHCP lease (causing any
> downloads to be re-processed, possibly with different parameters from
> the new lease), or re-download a statically defined URL.
> 
> This timeout defaults to five minutes (similar to pxelinux), and is
> configurable by DHCP option 211, "reboot time".

Note that these depend on a corresponding change to udhcpc:

  http://lists.busybox.net/pipermail/busybox/2018-July/086540.html

Cheers,


Jeremy