Re: [Etherboot-developers] [RFC] Relocation techniques...

[Peter L. <P.L...@sy...>]

> Is it possible to unload and reload the network driver that is connecting
> you to your root file system?

Linux has become a bit more careful about whether one can ifconfig down
a net driver which is in use, but since (unlike char and block devices)
there is no direct association between a network connection / socket and
the driver, then in principle yes. Even if not, it is easy enough to
create a "root" net device which can be mapped to the whichever net dev
is appropriate, in the same way that /dev/console is a way of
indirecting console output to /dev/tty0 or /dev/ttyS0 rather than
mapping to a physical device.

Anyway, networks being what they are, dropouts are expected and packets
just get resent. After all, there is no restriction on restarting the
NFS *server*, right? :) Personally I'd never use NFS for a root fs if I
could avoid it. Life easier would be easier if the root were a ramdisk,
or a network FS which likes to cache locally and doesn't mind extended
network outages.

> 2a. If you didn't already have a dhcpd.conf then one will have been
>     created for you based on your network configuration.  Just uncomment
>     and edit the "range" line and then restart dhcpd.
> *or*
> 2b. If you did already have a dhcpd.conf file then just add the line
>     "include /etc/dhcpd.conf.etherboot.include;" somewhere and restart
>     dhcpd.

I'm sure what you have done is fine but I've had practical experience of
an automatic dhcp configuration which automatically stomped on my dhcp
config because it was not what the installation "expected". Even
included files can cause dhcpd to not work, although they limit damage.

Extension Path (option 18) should be a much safer way to add dhcp config
chunks (see recent rant on ltsp-discuss) and need not even be done on
the machine running the dhcp server. I'll play with the Perl stuff;
producing raw DHCP options is quite easy, and it should be fairly
straightfoward to make it emit ISC dhcpd language, so we can have a
choice.