Network boot autoconfiguration sets default server to next server IP
(siaddr) from BOOTP/DHCP reply, but manual configuration using net_bootp
exports only server name. Unfortunately semantic of server name is not
clearly defined. BOOTP RFC 951 defines it only for client request, and
DHCP RFC 1541 only mentions it, without any implied usage. It looks like
this field is mostly empty in server replies.
Export next server IP as net_<interface>_next_server variable. This allows
grub configuration script to set $root/$prefix based on information obtained
by net_bootp.
Reported and tested by: Nikunj A Dadhania <nikunj@linux.vnet.ibm.com>
Cc: nikunj@linux.vnet.ibm.com
v2: change variable name to net_<interface>_next_server as discussed on the list
f8c3af3b61
