[libvirt] IPv6 migration

[Ján Tomko]

On 03/21/2013 11:52 AM, Daniel P. Berrange wrote:
> On Tue, Mar 19, 2013 at 03:21:31PM +0100, Jiri Denemark wrote:
>> On Mon, Mar 11, 2013 at 19:40:52 +0100, Ján Tomko wrote:
...
>>
>> Yeah, I think using an explicit flag would be the best approach. As we
>> learnt several times, implementing automagic behavior is too fragile and
>> leads to ugly code and confusion. IIUC, we would tell QEMU to listen on
>> :: iff either migrateuri uses IPv6 address explicitly or
>> VIR_DOMAIN_MIGRATE_IPV6 flag is set. In all other cases, 0.0.0.0 address
>> will be passed to QEMU. In other words, unless a user takes an explicit
>> action, migration will use IPv4 regardless on libvirt version.
> 
> That would mean that migration is broken by default in an IPv6 only
> environment, so I don't think that is an satisfactory approach. We
> should be checking whether.

Checking whether...?

> 
> Listening on '[::]' means that QEMU will accept connections on *both*
> IPv4 and IPv6, if configured with dual-stack. So if IPv6 is present
> on the target host, it is entirely reasonable to default to '[::]' if
> given a hostname.

I thought this might break IPv4 migration on FreeBSD, but QEMU turns
IPV6_V6ONLY off since the support of IPv6 migration in 1.1.

So this would only break migration with QEMU older than 1.1 and could be
worked around by specifying the IPv4 address in the migration URI?

Jan