[libvirt] dnsmasq-248 (CentOS/RHEL) compatibility

[Gene Czarcinski]

There are currently three significant libvirt patches I am involved with:

1. Change so that dnsmasq parameters are in a conf file instead of on 
the command line.

2. A small patch to add dnsmasq parameter interface=

3. A significant patch to add DHCPv6 support to libvirt.

A concern has been raised about the compatibility of my patches with 
dnsmasq-2.48 which is the version on CentOS 6 and RHEL 6.  While 
something like libvirt-1.0.0 is not officially supported, there is a 
strong desire not to get in the way of individuals back-porting it.

Plan A:  Install CentOS 6.3 into a virtual guest.  Apparently, the 
current virt-manager has some problems running CentOS 6.3.  Since I was 
here to drain a swap, I decided not to go after this alligator.

Plan B:  Get a the src.rpm for dnsmasq-2.48 from CentOS and build it on 
Fedora 17.  Then, using a Fedora 17  virtual guest, downgrade install 
dnsmasq-2.48 on it.

I then took four of my virtual dnsmasq conf-files than I use, slightly 
modify them to use interface=eth2 and common pid, hostsfile, addnhosts, 
and leases files.  I then fed each of these configuration files to 
dnsmasq-2.48.  Everything worked except for the one which had an IPv6 
dhcp-range specified.  That was not surprising dnsmasq-2.48 only 
supports IPv6 for dns.

If someone has some additional tests they would like run, please say so.

My recommendation:  Incorporate my patches [when I finish the DHCPv6 one 
and resubmit the others].  Add (somewhere?) a warning to backporters 
that they will need to update their dnsmasq packages to actually do 
DHCPv6 but otherwise, earlier versions such as dnsmasq-2.48 will be 
compatible.

Comments?  Suggestions?

Gene