Re: [Qemu-devel] [PATCH v4 3/9] cli: add -preconfig option

[Eduardo Habkost]

On Tue, Apr 03, 2018 at 03:49:07PM +0200, Igor Mammedov wrote:
> On Thu, 29 Mar 2018 13:57:54 -0300
> Eduardo Habkost <address@hidden> wrote:
> 
> [...]
> > > As for the future, I agree it would be much more flexible
> > > to allow both -preconfig and -incoming at the same time,
> > > so we could start target with empty CLI, and then feed it
> > > options from source. It would require audit/refactoring of
> > > INMIGRATE state and making 'all' current CLI options
> > > available via QMP interface.
> > > 
> > > But for now I'd prefer to keep using old way to start target.  
> > 
> > Well, if management software developers tell us that -preconfig
> > will be already useful without -incoming support, I won't object.
> As Peter said, mgmt can/will use -preconfig even without -incoming,
> since it lets deal with initial (source) start-up problem (i.e.
> avoid restarting QEMU) and lets us make numa configuration work
> in qemu/libvirt stack without guess work. (that's the end goal of
> the series)
> 
> > But it would be very nice for management software if they can
> > simply assume that -preconfig and -incoming will work together
> > since the first version.  Can we have this as a goal for 2.13?
> I can't promise to refactor -incoming in near future, as I'm working
> on ARM cpu-hotplug currently and next in queue is ARM memory hotplug.
> 
> Peter suggested an alternative idea, to abandon -incoming and
> enable incoming migration from QMP after all configuration is done.
> Amount of refactoring need probably would be the same but at least
> interface and runstate transitions wise it looks cleaner.

Also, support for the "start incoming migration" QMP command
would be very easy to probe using existing mechanisms.  Sounds
good to me.

-- 
Eduardo