Re: [Qemu-devel] IPv6 support for TCP migrations

["Daniel P. Berrange" <berrange@redhat.com>]

On Wed, May 04, 2011 at 09:39:02AM +0100, nick@bytemark.co.uk wrote:
> Hi,
> 
> Currently migration-tcp.c uses the IPv4-only socket functions, making
> migrations over IPv6 impossible. Following is a tentative patch that switches
> it to use inet_connect() and inet_listen(). 
> 
> However, the patch loses the non-blocking connect() behaviour seen with the
> previous code. I'm not sure how much of an issue this is - if connect() blocks
> here, does it block execution of the VM? 
> 
> If so, I guess we need a non-blocking form of inet_connect(), or some way of
> replicating the behaviour - it would potentially be needed for my NBD
> reconnection patches too? I can see that a blocking connect() might not be an
> issue while the KVM process is starting up, but could cause problems if we
> try to reconnect while emulation is ongoing.
> 
> Thoughts?

FWIW, Juan Quintela also posted a set of patches to add IPv6 support for
migration a few weeks back, but unfortunately they don't appear to have
been merged yet:

  http://www.mail-archive.com/qemu-devel@nongnu.org/msg58954.html

IIUC, Juan's patches don't have the blocking connect() problem you
mention.

Regards,
Daniel
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