[libvirt] dhcp6, radvd, ip6tables, etc. (update)

Laine Stump laine at laine.org
Thu Nov 1 01:50:16 UTC 2012

On 10/31/2012 03:11 PM, Gene Czarcinski wrote:
> On 10/31/2012 11:53 AM, Laine Stump wrote:
>> That's just a safeguard to enforce the ipv4-only status of dhcp in the
>> current libvirt. Just remove that restriction from the function
>> virNetworkDefUpdateIP() as a part of your patch adding ipv6 dhcp
>> support.
> OK, removing the ipv4 test has net-update ipv6 working as well as ipv4
> does.
> Observation: this is definitely a work-in-progress.  I only tried
> ip-dhcp-range and ip-dhcp-host.  The ip-dhcp-range produced the
> expected in the the xml was updated and dnsmasq was restarted.  With
> ip-dhcp-host, it only did the right thing if the network was down. If
> it was started, nothing much happened.

Most likely because, according to what you recently wrote, the dhcp
hosts file isn't reread when a SIGHUP is sent to dnsmasq.

> A suggestion, before F18 goes with 0.10.2, I suggest that the virsh
> man-page be updated.  Currently, you would think that all of the stuff
> worked.  Clearly, it does not.  At best, users will be confused.  I
> suggest listing the functions that are planned but not currently
> implemented.

A valid point.

Note that it's not vanilla 0.10.2 that's currently in F18, it's the
0.20.2-maint branch, which is 0.10.2 plus some bugfixes deemed worthy of
backporting. Patches can be added to that branch at any time during the
lifetime of F18 (and even beyond if some other distro is using that
release for their builds), but they are only bugfixes (adding the
backend for missing sections could be seen as fixing a bug, if we
*really* wanted to :-).

> Speaking of documentation.  This should be updated for DHCPv6:
> http://libvirt.org/http://libvirt.org/formatnetwork.html and there is
> docs/http://libvirt.org/formatnetwork.html.in in the git. However, it
> is not clear what the process is for changing/updating the documentation.

Just edit formatnetwork.html.in and make that edit a part of the same
patch that makes the new functionality available. Your patch would be
NACKed without that anyway.

> Doing a grep on the log does not show a lot of commits being performed
> on it.

Any change to the network XML is not accepted for a push unless a change
to formatnetwork.html.in accompanies it. Any low patch volume on the
file is due to there being infrequent changes in the XML.

> While a lot of using IPv6/DHCP6 is straight-forward, there are a
> couple of twists such as not specifying a MAC address for a v6
> dhcp-host specification.

> I know there is some touchiness about this so I am thinking of adding
> a "special xml keyword" which would switch between radvd and dnsmasq.

I'm not sure whether that would be appropriate, or to instead have an
autoconf option that would enact the change at compile time.

> BTW, I am assuming this is all post v1.0.0.

We've been in freeze for the last week, and at this point only simple
fixes to very serious bugs are being pushed. New functionality is
definnitely post-1.0.0

>   I have currently completed the dhcp6 patch (net-update was the last 
> piece) but I need to let things work for a while to see if I missed
> anything.  If anyone wants to look at these patches, I can post them
> to this list or send them direct.  However, I want to wait until
> v1.0.0 gets released before submitting them for review, etc.

You can submit things for review now, they just won't be pushed until
after the release is cut.

More information about the libvir-list mailing list