[libvirt] [PATCH v13] support offline migration

[Jiri Denemark]

On Mon, Nov 12, 2012 at 09:26:30 +0800, li guang wrote:
> 在 2012-11-09五的 13:00 +0100，Jiri Denemark写道：
> > On Fri, Nov 09, 2012 at 10:57:23 +0800, li guang wrote:
> >
> > Well, and that's the thing that actually needs fixing. The migration code in
> > libvirt.c and the code doing peer-to-peer migration in qemu_migration.c are
> > very similar because they are doing almost the same job (only at different
> > levels). It makes sense to change them both at the same time. Why do you want
> > to avoid changing code in libvirt.c?
> 
> first, I think it's clean enough for my patch to do offline migration,
> second, someone told me to keep public API stability of libvirt
> before(it's not clear who and when), so I fear to change.

Well, don't worry I'm aware of API/ABI stability we need to maintain in
libvirt and I wouldn't suggest you to do something that would break anything
in that area. Of course you can't add new parameters to existing public
functions, for example. But changing the code inside to support new flags is
allowed.

> you mean I should take care of fixing or re-factoring redundant code
> this time? maybe I can try to do something after this patch.

No. It's just that the migration code in libvirt.c and the p2p code in
qemu_migration.c are very similar since they are doing the same thing at
different levels. You can't really refactor that and I'm not asking you to do
so. However, since the code logic is similar in both places, it's wise to keep
it that way and just skip Perform phase for offline migrations regardless on
the actual type of migration. I'd much like to see that rather than hacking
somewhere inside the code doing Perform phase to exit if it notices it should
not have been run at all.

Jirka