| Message ID | e8f3a6058ada9550dc73b825158fbd0248c2606c.1371804804.git.hutao@cn.fujitsu.com |
|---|---|
| State | New |
| Headers | show |
On Sat, 22 Jun 2013 16:50:33 +0800 Hu Tao <hutao@cn.fujitsu.com> wrote: > Cc: qemu-devel@nongnu.org > Cc: "Andreas Färber" <afaerber@suse.de> > Cc: Paolo Bonzini <pbonzini@redhat.com> > Cc: Anthony Liguori <aliguori@us.ibm.com> > Cc: Igor Mammedov <imammedo@redhat.com> > Cc: Eduardo Habkost <ehabkost@redhat.com> > Signed-off-by: Hu Tao <hutao@cn.fujitsu.com> > --- > hw/i386/kvm/clock.c | 8 +++----- > 1 file changed, 3 insertions(+), 5 deletions(-) > > diff --git a/hw/i386/kvm/clock.c b/hw/i386/kvm/clock.c > index 87d4d0f..74aa240 100644 > --- a/hw/i386/kvm/clock.c > +++ b/hw/i386/kvm/clock.c > @@ -87,12 +87,11 @@ static void kvmclock_vm_state_change(void *opaque, int running, > } > } > > -static int kvmclock_init(SysBusDevice *dev) > +static void kvmclock_realize(DeviceState *dev, Error **errp) > { > - KVMClockState *s = FROM_SYSBUS(KVMClockState, dev); > + KVMClockState *s = DO_UPCAST(KVMClockState, busdev.qdev, dev); it would be better to swap this patch with 22/26 and use KVM_CLOCK() cast here > > qemu_add_vm_change_state_handler(kvmclock_vm_state_change, s); > - return 0; > } > > static const VMStateDescription kvmclock_vmsd = { > @@ -111,9 +110,8 @@ static const VMStateDescription kvmclock_vmsd = { > static void kvmclock_class_init(ObjectClass *klass, void *data) > { > DeviceClass *dc = DEVICE_CLASS(klass); > - SysBusDeviceClass *k = SYS_BUS_DEVICE_CLASS(klass); > > - k->init = kvmclock_init; > + dc->realize = kvmclock_realize; > dc->no_user = 1; > dc->vmsd = &kvmclock_vmsd; > }
On Sat, Jun 22, 2013 at 04:50:33PM +0800, Hu Tao wrote: > Cc: qemu-devel@nongnu.org > Cc: "Andreas Färber" <afaerber@suse.de> > Cc: Paolo Bonzini <pbonzini@redhat.com> > Cc: Anthony Liguori <aliguori@us.ibm.com> > Cc: Igor Mammedov <imammedo@redhat.com> > Cc: Eduardo Habkost <ehabkost@redhat.com> > Signed-off-by: Hu Tao <hutao@cn.fujitsu.com> > --- > hw/i386/kvm/clock.c | 8 +++----- > 1 file changed, 3 insertions(+), 5 deletions(-) > > diff --git a/hw/i386/kvm/clock.c b/hw/i386/kvm/clock.c > index 87d4d0f..74aa240 100644 > --- a/hw/i386/kvm/clock.c > +++ b/hw/i386/kvm/clock.c > @@ -87,12 +87,11 @@ static void kvmclock_vm_state_change(void *opaque, int running, > } > } > > -static int kvmclock_init(SysBusDevice *dev) > +static void kvmclock_realize(DeviceState *dev, Error **errp) > { > - KVMClockState *s = FROM_SYSBUS(KVMClockState, dev); > + KVMClockState *s = DO_UPCAST(KVMClockState, busdev.qdev, dev); > > qemu_add_vm_change_state_handler(kvmclock_vm_state_change, s); > - return 0; > } > > static const VMStateDescription kvmclock_vmsd = { > @@ -111,9 +110,8 @@ static const VMStateDescription kvmclock_vmsd = { > static void kvmclock_class_init(ObjectClass *klass, void *data) > { > DeviceClass *dc = DEVICE_CLASS(klass); > - SysBusDeviceClass *k = SYS_BUS_DEVICE_CLASS(klass); > > - k->init = kvmclock_init; > + dc->realize = kvmclock_realize; Is TYPE_SYS_BUS_DEVICE guaranteed to never override ->realize() itself? From DeviceClass documentation: * If a type derived directly from TYPE_DEVICE implements @realize, it does * not need to implement @init and therefore does not need to store and call * #DeviceClass' default @realize callback. * For other types consult the documentation and implementation of the * respective parent types. The problem is that there's no documentation about ->realize() on SysBusDeviceClass. Can we please explicitly document SysBusDeviceClass expectations about ->realize() first, before making those changes? > dc->no_user = 1; > dc->vmsd = &kvmclock_vmsd; > } > -- > 1.8.3.1 > >
On Mon, Jun 24, 2013 at 12:14:07PM +0200, Igor Mammedov wrote: > On Sat, 22 Jun 2013 16:50:33 +0800 > Hu Tao <hutao@cn.fujitsu.com> wrote: > > > Cc: qemu-devel@nongnu.org > > Cc: "Andreas Färber" <afaerber@suse.de> > > Cc: Paolo Bonzini <pbonzini@redhat.com> > > Cc: Anthony Liguori <aliguori@us.ibm.com> > > Cc: Igor Mammedov <imammedo@redhat.com> > > Cc: Eduardo Habkost <ehabkost@redhat.com> > > Signed-off-by: Hu Tao <hutao@cn.fujitsu.com> > > --- > > hw/i386/kvm/clock.c | 8 +++----- > > 1 file changed, 3 insertions(+), 5 deletions(-) > > > > diff --git a/hw/i386/kvm/clock.c b/hw/i386/kvm/clock.c > > index 87d4d0f..74aa240 100644 > > --- a/hw/i386/kvm/clock.c > > +++ b/hw/i386/kvm/clock.c > > @@ -87,12 +87,11 @@ static void kvmclock_vm_state_change(void *opaque, int running, > > } > > } > > > > -static int kvmclock_init(SysBusDevice *dev) > > +static void kvmclock_realize(DeviceState *dev, Error **errp) > > { > > - KVMClockState *s = FROM_SYSBUS(KVMClockState, dev); > > + KVMClockState *s = DO_UPCAST(KVMClockState, busdev.qdev, dev); > it would be better to swap this patch with 22/26 and use KVM_CLOCK() cast here OK. I'll swap them in next version.
On Mon, Jun 24, 2013 at 11:01:54AM -0300, Eduardo Habkost wrote: > On Sat, Jun 22, 2013 at 04:50:33PM +0800, Hu Tao wrote: > > Cc: qemu-devel@nongnu.org > > Cc: "Andreas Färber" <afaerber@suse.de> > > Cc: Paolo Bonzini <pbonzini@redhat.com> > > Cc: Anthony Liguori <aliguori@us.ibm.com> > > Cc: Igor Mammedov <imammedo@redhat.com> > > Cc: Eduardo Habkost <ehabkost@redhat.com> > > Signed-off-by: Hu Tao <hutao@cn.fujitsu.com> > > --- > > hw/i386/kvm/clock.c | 8 +++----- > > 1 file changed, 3 insertions(+), 5 deletions(-) > > > > diff --git a/hw/i386/kvm/clock.c b/hw/i386/kvm/clock.c > > index 87d4d0f..74aa240 100644 > > --- a/hw/i386/kvm/clock.c > > +++ b/hw/i386/kvm/clock.c > > @@ -87,12 +87,11 @@ static void kvmclock_vm_state_change(void *opaque, int running, > > } > > } > > > > -static int kvmclock_init(SysBusDevice *dev) > > +static void kvmclock_realize(DeviceState *dev, Error **errp) > > { > > - KVMClockState *s = FROM_SYSBUS(KVMClockState, dev); > > + KVMClockState *s = DO_UPCAST(KVMClockState, busdev.qdev, dev); > > > > qemu_add_vm_change_state_handler(kvmclock_vm_state_change, s); > > - return 0; > > } > > > > static const VMStateDescription kvmclock_vmsd = { > > @@ -111,9 +110,8 @@ static const VMStateDescription kvmclock_vmsd = { > > static void kvmclock_class_init(ObjectClass *klass, void *data) > > { > > DeviceClass *dc = DEVICE_CLASS(klass); > > - SysBusDeviceClass *k = SYS_BUS_DEVICE_CLASS(klass); > > > > - k->init = kvmclock_init; > > + dc->realize = kvmclock_realize; > > Is TYPE_SYS_BUS_DEVICE guaranteed to never override ->realize() itself? > > From DeviceClass documentation: > > * If a type derived directly from TYPE_DEVICE implements @realize, it does > * not need to implement @init and therefore does not need to store and call > * #DeviceClass' default @realize callback. > * For other types consult the documentation and implementation of the > * respective parent types. > > The problem is that there's no documentation about ->realize() on > SysBusDeviceClass. Can we please explicitly document SysBusDeviceClass > expectations about ->realize() first, before making those changes? IIUC, subclass's overriding ->realize should call parent's ->realize at some point. Peter Crosthwaite has a patchset to access a object's parent class at http://lists.nongnu.org/archive/html/qemu-devel/2013-06/msg02982.html Regarding SysBusDevice::init and SysBusDevice::realize, I think it's the same as in the case of DeviceClass. If you agree I'll document it as in DeviceClass.
On Tue, Jun 25, 2013 at 10:20:08AM +0800, Hu Tao wrote: [...] > > Is TYPE_SYS_BUS_DEVICE guaranteed to never override ->realize() itself? > > > > From DeviceClass documentation: > > > > * If a type derived directly from TYPE_DEVICE implements @realize, it does > > * not need to implement @init and therefore does not need to store and call > > * #DeviceClass' default @realize callback. > > * For other types consult the documentation and implementation of the > > * respective parent types. > > > > The problem is that there's no documentation about ->realize() on > > SysBusDeviceClass. Can we please explicitly document SysBusDeviceClass > > expectations about ->realize() first, before making those changes? > > IIUC, subclass's overriding ->realize should call parent's ->realize at > some point. Peter Crosthwaite has a patchset to access a object's parent > class at http://lists.nongnu.org/archive/html/qemu-devel/2013-06/msg02982.html > > Regarding SysBusDevice::init and SysBusDevice::realize, I think it's the > same as in the case of DeviceClass. If you agree I'll document it as in > DeviceClass. I believe it is reasonable to document that SysBusDevice subclasses don't need to call the parent ->realize() method, like on DeviceClass. This is exactly what this patch set does, after all, and I haven't seen anybody complaining about it yet.
Am 25.06.2013 19:45, schrieb Eduardo Habkost: > On Tue, Jun 25, 2013 at 10:20:08AM +0800, Hu Tao wrote: > [...] >>> Is TYPE_SYS_BUS_DEVICE guaranteed to never override ->realize() itself? >>> >>> From DeviceClass documentation: >>> >>> * If a type derived directly from TYPE_DEVICE implements @realize, it does >>> * not need to implement @init and therefore does not need to store and call >>> * #DeviceClass' default @realize callback. >>> * For other types consult the documentation and implementation of the >>> * respective parent types. >>> >>> The problem is that there's no documentation about ->realize() on >>> SysBusDeviceClass. Can we please explicitly document SysBusDeviceClass >>> expectations about ->realize() first, before making those changes? If someone wants to add a paragraph to sysbus.h:SysBusDeviceClass documentation I would happily ack or pick that up. :) >> IIUC, subclass's overriding ->realize should call parent's ->realize at >> some point. Peter Crosthwaite has a patchset to access a object's parent >> class at http://lists.nongnu.org/archive/html/qemu-devel/2013-06/msg02982.html >> >> Regarding SysBusDevice::init and SysBusDevice::realize, I think it's the >> same as in the case of DeviceClass. If you agree I'll document it as in >> DeviceClass. > > I believe it is reasonable to document that SysBusDevice subclasses > don't need to call the parent ->realize() method, like on DeviceClass. > This is exactly what this patch set does, after all, and I haven't seen > anybody complaining about it yet. So the thing is that SysBusDevice's DeviceClass::init implementation, called by DeviceState's DeviceClass::realize implementation, just calls SysBusDeviceClass::init if non-NULL. When we introduce our own device's realizefn to replace our SysBusDeviceClass::init implementation, there is no point calling that effectively no-op DeviceClass::realize implementation. And if we tried to, ... * ... how would we decide whether to call the parent's implementation first or last? It's not yes or no, it's no or when. Changing between either is more than just moving one line, it affects error handling and with knowledge about parent implementation never failing we could so far save us some work. * ... with the current QOM method scheme we'd go insane introducing a FooClass per device to save SysBusDevice's DeviceClass::realize in FooClass::parent_realize. Still waiting for Anthony on whether and how we want to change our scheme. Long story short: If someone wants to mess with base classes they get to check derived classes for compatibility with their change. Ideally qtest would help automate that to some degree. I would be all in favor if someone wanted to add a dummy test case per non-default, non-KVM device converted so that we can see that we didn't screw up -device instantiation too badly. Regards, Andreas
On Sun, Jun 30, 2013 at 04:36:13PM +0200, Andreas Färber wrote: > Am 25.06.2013 19:45, schrieb Eduardo Habkost: > > On Tue, Jun 25, 2013 at 10:20:08AM +0800, Hu Tao wrote: > > [...] > >>> Is TYPE_SYS_BUS_DEVICE guaranteed to never override ->realize() itself? > >>> > >>> From DeviceClass documentation: > >>> > >>> * If a type derived directly from TYPE_DEVICE implements @realize, it does > >>> * not need to implement @init and therefore does not need to store and call > >>> * #DeviceClass' default @realize callback. > >>> * For other types consult the documentation and implementation of the > >>> * respective parent types. > >>> > >>> The problem is that there's no documentation about ->realize() on > >>> SysBusDeviceClass. Can we please explicitly document SysBusDeviceClass > >>> expectations about ->realize() first, before making those changes? > > If someone wants to add a paragraph to sysbus.h:SysBusDeviceClass > documentation I would happily ack or pick that up. :) > > >> IIUC, subclass's overriding ->realize should call parent's ->realize at > >> some point. Peter Crosthwaite has a patchset to access a object's parent > >> class at http://lists.nongnu.org/archive/html/qemu-devel/2013-06/msg02982.html > >> > >> Regarding SysBusDevice::init and SysBusDevice::realize, I think it's the > >> same as in the case of DeviceClass. If you agree I'll document it as in > >> DeviceClass. > > > > I believe it is reasonable to document that SysBusDevice subclasses > > don't need to call the parent ->realize() method, like on DeviceClass. > > This is exactly what this patch set does, after all, and I haven't seen > > anybody complaining about it yet. > > So the thing is that SysBusDevice's DeviceClass::init implementation, > called by DeviceState's DeviceClass::realize implementation, just calls > SysBusDeviceClass::init if non-NULL. When we introduce our own device's > realizefn to replace our SysBusDeviceClass::init implementation, there > is no point calling that effectively no-op DeviceClass::realize > implementation. This is true because we are in transition from DeviceClass:init to DeviceClass:realize, by calling sub-class's DeviceClass:init in DeviceClass's realize. But once the transition is done, and DeviceClass's (and any intermediate devired classes') realize does do something, we can't just ignore it in overriding realize. Fix me if i'm wrong. > And if we tried to, ... > * ... how would we decide whether to call the parent's implementation > first or last? It's not yes or no, it's no or when. Changing between > either is more than just moving one line, it affects error handling and > with knowledge about parent implementation never failing we could so far > save us some work. Agreed. > * ... with the current QOM method scheme we'd go insane introducing a > FooClass per device to save SysBusDevice's DeviceClass::realize in > FooClass::parent_realize. Still waiting for Anthony on whether and how > we want to change our scheme. > > Long story short: If someone wants to mess with base classes they get to > check derived classes for compatibility with their change. > > Ideally qtest would help automate that to some degree. > I would be all in favor if someone wanted to add a dummy test case per > non-default, non-KVM device converted so that we can see that we didn't > screw up -device instantiation too badly. > > Regards, > Andreas > > -- > SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg, Germany > GF: Jeff Hawn, Jennifer Guild, Felix Imendörffer; HRB 16746 AG Nürnberg
Am 01.07.2013 11:31, schrieb Hu Tao: > On Sun, Jun 30, 2013 at 04:36:13PM +0200, Andreas Färber wrote: >> Am 25.06.2013 19:45, schrieb Eduardo Habkost: >>> On Tue, Jun 25, 2013 at 10:20:08AM +0800, Hu Tao wrote: >>> [...] >>>>> Is TYPE_SYS_BUS_DEVICE guaranteed to never override ->realize() itself? >>>>> >>>>> From DeviceClass documentation: >>>>> >>>>> * If a type derived directly from TYPE_DEVICE implements @realize, it does >>>>> * not need to implement @init and therefore does not need to store and call >>>>> * #DeviceClass' default @realize callback. >>>>> * For other types consult the documentation and implementation of the >>>>> * respective parent types. >>>>> >>>>> The problem is that there's no documentation about ->realize() on >>>>> SysBusDeviceClass. Can we please explicitly document SysBusDeviceClass >>>>> expectations about ->realize() first, before making those changes? >> >> If someone wants to add a paragraph to sysbus.h:SysBusDeviceClass >> documentation I would happily ack or pick that up. :) >> >>>> IIUC, subclass's overriding ->realize should call parent's ->realize at >>>> some point. Peter Crosthwaite has a patchset to access a object's parent >>>> class at http://lists.nongnu.org/archive/html/qemu-devel/2013-06/msg02982.html >>>> >>>> Regarding SysBusDevice::init and SysBusDevice::realize, I think it's the >>>> same as in the case of DeviceClass. If you agree I'll document it as in >>>> DeviceClass. >>> >>> I believe it is reasonable to document that SysBusDevice subclasses >>> don't need to call the parent ->realize() method, like on DeviceClass. >>> This is exactly what this patch set does, after all, and I haven't seen >>> anybody complaining about it yet. >> >> So the thing is that SysBusDevice's DeviceClass::init implementation, >> called by DeviceState's DeviceClass::realize implementation, just calls >> SysBusDeviceClass::init if non-NULL. When we introduce our own device's >> realizefn to replace our SysBusDeviceClass::init implementation, there >> is no point calling that effectively no-op DeviceClass::realize >> implementation. > > This is true because we are in transition from DeviceClass:init to > DeviceClass:realize, by calling sub-class's DeviceClass:init in > DeviceClass's realize. Correct. > But once the transition is done, and > DeviceClass's (and any intermediate devired classes') realize does > do something, we can't just ignore it in overriding realize. We have the following hierarchy: Object +Device + SysBusDevice + EHCI + FaradayEHCI Object does not know about realize. Device has a realizefn that calls DeviceClass::init today, nothing more. Therefore SysBusDevice doesn't need to additionally call that today. Since, e.g., EHCI implements a realizefn, derived types need to call their parent's realizefn, i.e. FaradayEHCI EHCI's or if there were another model F derived from Faraday, then F FaradayEHCI's. Correct. Once the transition is done, I expect those four lines to go away, with Device's realizefn seriously doing nothing, as a fallback to avoid if (dc->realized) {...} type code. The sysbus_get_default() assignment could easily be moved to SysBusDevice's instance_init, so I don't see anything from qdev_create() / qdev_init() that would need to be moved there. Do you? The way Paolo proposed it, realize_children would be separate from realize and called directly from DeviceState's property setter, so it could be overridden independently. Andreas >> And if we tried to, ... >> * ... how would we decide whether to call the parent's implementation >> first or last? It's not yes or no, it's no or when. Changing between >> either is more than just moving one line, it affects error handling and >> with knowledge about parent implementation never failing we could so far >> save us some work. > > Agreed. > >> * ... with the current QOM method scheme we'd go insane introducing a >> FooClass per device to save SysBusDevice's DeviceClass::realize in >> FooClass::parent_realize. Still waiting for Anthony on whether and how >> we want to change our scheme. >> >> Long story short: If someone wants to mess with base classes they get to >> check derived classes for compatibility with their change. >> >> Ideally qtest would help automate that to some degree. >> I would be all in favor if someone wanted to add a dummy test case per >> non-default, non-KVM device converted so that we can see that we didn't >> screw up -device instantiation too badly. >> >> Regards, >> Andreas >> >> -- >> SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg, Germany >> GF: Jeff Hawn, Jennifer Guild, Felix Imendörffer; HRB 16746 AG Nürnberg
diff --git a/hw/i386/kvm/clock.c b/hw/i386/kvm/clock.c index 87d4d0f..74aa240 100644 --- a/hw/i386/kvm/clock.c +++ b/hw/i386/kvm/clock.c @@ -87,12 +87,11 @@ static void kvmclock_vm_state_change(void *opaque, int running, } } -static int kvmclock_init(SysBusDevice *dev) +static void kvmclock_realize(DeviceState *dev, Error **errp) { - KVMClockState *s = FROM_SYSBUS(KVMClockState, dev); + KVMClockState *s = DO_UPCAST(KVMClockState, busdev.qdev, dev); qemu_add_vm_change_state_handler(kvmclock_vm_state_change, s); - return 0; } static const VMStateDescription kvmclock_vmsd = { @@ -111,9 +110,8 @@ static const VMStateDescription kvmclock_vmsd = { static void kvmclock_class_init(ObjectClass *klass, void *data) { DeviceClass *dc = DEVICE_CLASS(klass); - SysBusDeviceClass *k = SYS_BUS_DEVICE_CLASS(klass); - k->init = kvmclock_init; + dc->realize = kvmclock_realize; dc->no_user = 1; dc->vmsd = &kvmclock_vmsd; }
Cc: qemu-devel@nongnu.org Cc: "Andreas Färber" <afaerber@suse.de> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Anthony Liguori <aliguori@us.ibm.com> Cc: Igor Mammedov <imammedo@redhat.com> Cc: Eduardo Habkost <ehabkost@redhat.com> Signed-off-by: Hu Tao <hutao@cn.fujitsu.com> --- hw/i386/kvm/clock.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-)