On Mon, Sep 07, 2015 at 06:53:49PM +0800, Yang Hongyang wrote: > On 09/07/2015 05:11 PM, Stefan Hajnoczi wrote: > [...] > >>Thanks very much for the suggestion, I've already implemented it and tested, > >>the code looks cleaner now. > >> > >>The last issue is the QOM thing, do Markus and Andreas have more input > >>about that? > > > >If you would like to see examples of QOM usage, take a look at > >iothread.c and/or backends/hostmem.c. > > > >The key things are: > > > >1. They use include/qom/object.h to register a type based on > > TYPE_OBJECT and their properties are registered using > > object_property_add_*(). > > > >2. They implement the TYPE_USER_CREATABLE interface so the -object > > command-line option can be used to instantiate them. See > > object_interfaces.h. > > > >As a result, a lot of code becomes unnecessary and iothread.c, in > >particular, is quite short. > > After looking into this, I have some questions on the implement, could you > please help me on this because I don't know much about the object mechanism: > > The netfilter need to be initialized after the net_init_clients, because we > need to attach the filter to the net client. But currently, net client is not > using QOM, and seems that it is initialized after objects been created. So > here > comes the problem: how can I initialize a certain object later, is it > possiable?
It is currently a bit hacky - most objects are initialized very early, but we have a similar problem with rng-egd which must be created /after/ chardevs. To deal with this in vl.c main() we have two helper methods object_create_initial and object_create_delayed. The delayed method though still happens before the net clients are created. We could probably just move the objec_create_delayed method invokation to later on, after net clients are created, but if that doesn't work just add an extra helper object_create_very_delayed :-) Regards, Daniel -- |: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| |: http://libvirt.org -o- http://virt-manager.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :|
