On Tue, Jun 13, 2017 at 11:41:02AM +0800, Peter Xu wrote: > On Mon, Jun 12, 2017 at 04:18:06PM +0800, Peter Xu wrote: > > On Fri, Jun 09, 2017 at 10:40:10AM -0300, Eduardo Habkost wrote: > > > On Fri, Jun 09, 2017 at 11:48:59AM +0800, Peter Xu wrote: > > > > Put it into MigrationState then we can use the properties to specify > > > > whether to enable storing global state. > > > > > > > > Removing global_state_set_optional() since now we can use HW_COMPAT_2_3 > > > > for x86/power in general, and the register_compat_prop() for xen_init(). > > > > > > > > Signed-off-by: Peter Xu <pet...@redhat.com> [...] > > > > diff --git a/hw/xen/xen-common.c b/hw/xen/xen-common.c > > > > index 0bed577..8240d50 100644 > > > > --- a/hw/xen/xen-common.c > > > > +++ b/hw/xen/xen-common.c > > > > @@ -138,7 +138,13 @@ static int xen_init(MachineState *ms) > > > > } > > > > qemu_add_vm_change_state_handler(xen_change_state_handler, NULL); > > > > > > > > - global_state_set_optional(); > > > > + /* > > > > + * TODO: make sure global MigrationState has not yet been created > > > > + * (otherwise the compat trick won't work). For now we are in > > > > + * configure_accelerator() so we are mostly good. Better to > > > > + * confirm that in the future. > > > > + */ > > > > > > So, this makes accelerator initialization very sensitive to > > > ordering. > > > > > > > + register_compat_prop("migration", "store-global-state", "off"); > > > > > > It's already hard to track down machine-type stuff that is > > > initialized at machine->init() time but it's not introspectable, > > > let's not do the same mistake with accelerators. > > > > > > Can't this be solved by a AcceleratorClass::global_props field, > > > so we are sure there's a single place in the code where globals > > > are registered? (Currently, they are all registered by the few > > > lines around the machine_register_compat_props() call in main()). > > > > > > I think I see other use cases for a new > > > AcceleratorClass::global_props field. e.g.: replacing > > > kvm_default_props and tcg_default_props in target/i386/cpu.c. > > > > Hmm, this sounds nice. Then we can also get rid of the TODO above. > > > > Thanks for your suggestion and review! I'll see whether I can writeup > > something as RFC for this. > > After a second thought, I see these requirements are slightly > different. > > For xen_init(), AccelClass::global_props may help since that's mainly > properties to be setup for TYPE_MIGRATION (let's assume it's okay that > MigrationState can be a QDev). > > For kvm_default_props and tcg_default_props, AccelClass::global_props > may not help since they are setting up properties for TYPE_CPU, and > TYPE_CPU cannot really use global property features yet. :(
TYPE_CPU can use global properties, for sure. TYPE_CPU is a TYPE_DEVICE subclass, and -cpu is implemented internally using global properties. > > If finally we can have a new way (e.g., as you suggested in the other > thread, using a new INTERFACE to show that one QObject supports global > qdev properties) to allow TYPE_CPU to use global properties, then > these two requirements can merge. Otherwise IMHO we may still need to > keep the *_default_props in CPU codes. > > Thanks, > > -- > Peter Xu -- Eduardo