On Thu, 4 Oct 2012 09:43:41 -0300 Eduardo Habkost <ehabk...@redhat.com> wrote:
> On Thu, Oct 04, 2012 at 08:53:22AM +0200, Igor Mammedov wrote: > > On Wed, 3 Oct 2012 13:54:34 -0300 > > Eduardo Habkost <ehabk...@redhat.com> wrote: > > > > > On Wed, Oct 03, 2012 at 06:24:11PM +0200, Igor Mammedov wrote: > > > > On Wed, 03 Oct 2012 17:20:46 +0200 > > > > Paolo Bonzini <pbonz...@redhat.com> wrote: > > > > > > > > > Il 03/10/2012 17:03, Eduardo Habkost ha scritto: > > > > > > On Tue, Oct 02, 2012 at 05:38:45PM -0300, Eduardo Habkost wrote: > > > > > >> (Now replying on the right thread, to keep the discussion in the > > > > > >> right place. I don't know how I ended up replying to a > > > > > >> pre-historic version of the patch, sorry.) > > > > > >> > > > > > >> On Tue, Oct 02, 2012 at 05:36:59PM +0200, Igor Mammedov wrote: > > > > > >> [...] > > > > > >>> @@ -1938,6 +2043,12 @@ static void x86_cpu_initfn(Object *obj) > > > > > >>> object_property_add(obj, "tsc-frequency", "int", > > > > > >>> x86_cpuid_get_tsc_freq, > > > > > >>> x86_cpuid_set_tsc_freq, NULL, NULL, > > > > > >>> NULL); > > > > > >>> + x86_register_cpuid_properties(obj, feature_name); > > > > > >>> + x86_register_cpuid_properties(obj, ext_feature_name); > > > > > >>> + x86_register_cpuid_properties(obj, ext2_feature_name); > > > > > >>> + x86_register_cpuid_properties(obj, ext3_feature_name); > > > > > >>> + x86_register_cpuid_properties(obj, kvm_feature_name); > > > > > >>> + x86_register_cpuid_properties(obj, svm_feature_name); > > > > > >> > > > > > >> Stupid question about qdev: > > > > > >> > > > > > >> - qdev_prop_set_globals() is called from device_initfn() > > > > > >> - device_initfn() is called before the child class > > > > > >> instance_init() function (x86_cpu_initfn()) > > > > > >> - So, qdev_prop_set_globals() gets called before the CPU class > > > > > >> properties are registered. > > > > > >> > > > > > >> So this would defeat the whole point of all the work we're doing, > > > > > >> that is to allow compatibility bits to be set as machine-type > > > > > >> global properties. But I don't know what's the right solution > > > > > >> here. > > > > > >> > > > > > >> Should the qdev_prop_set_globals() call be moved to qdev_init() > > > > > >> instead? Should the CPU properties be registered somewhere else? > > > > > > > > > > Properties should be registered (for all objects, not just CPUs) in > > > > > the instance_init function. This is device_initfn. > > > > > > > > > > I would add an instance_postinit function that is called at the end > > > > > of object_initialize_with_type, that is after instance_init, and in > > > > > the opposite order (i.e. from the leaf to the root). > > > > > > > > You've meant something like that? > > > > > > > > > > That's almost exactly the same code I wrote here. :-) > > > > > > The only difference is that I added post_init to the struct Object > > > documentation comments, and added a unit test. The unit test required > > > the qdev-core/qdev split, so we could compile it without bringing too > > > many dependencies. I will submit it soon. > > > > > After irc discussion, Anthony suggested to use static properties instead > > of dynamic ones that we use now. > > > > But qdev_prop_set_globals() in device_initfn() is still causes problems > > even with static properties. > > > > For x86 CPU classes we were going dynamically generate CPU classes and > > store pointer to appropriate cpudef from builtin_x86_defs in class field > > for each CPU class and then init default feature words values from this > > field int x86_cpu_initfn(). > > > > However with qdev_prop_set_globals() in device_initfn() that is called > > before x86_cpu_initfn() it won't work because defaults in > > x86_cpu_initfn() will overwrite whatever was set by > > qdev_prop_set_globals(). > > We can set the default values on class_init, instead. The class_init > function for each CPU model can get the x86_def_t struct as the data > pointer. > > I still think that the interface to build the DeviceClass.props array on > class_init is really painful to use, but it's still doable. You mean dynamic building of DeviceClass.props arrays for each CPU sub-class? > > > > > IMHO from general POV it's not correct to set properties before object is > > completely created. > > If I understood it correctly, the point of all this is to allow > properties (and their defaults) to be introspected by just looking at > the class, without having to create any object. > > IMO the problem is that we don't have any decent mechanism to implement > machine-type compatibility behavior that doesn't involve having to deal > with the strict rules of global properties. All this work is blocking us > from implementing many necessary bug fixes. > > It's OK if the long-term goal is to move the code to this generic, > flexible, fully-instropectable, complex framework, but we need to have a > way to implement bug fixes without waiting for all this work to be > finished. > > > > But Anthony wants to keep qdev_prop_set_globals() qdev only thing, so > > could we move it from device_initfn() to qdev_init() or some other place > > then? >
