| Message ID | 20210117192446.23753-3-f4bug@amsat.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | hw: Mark the device with no migratable fields | expand |
* Philippe Mathieu-Daudé (f4bug@amsat.org) wrote: > Add vmstate_qdev_no_state_to_migrate, which is simply a > pointer to vmstate_no_state_to_migrate. This way all > qdev devices (including "hw/qdev-core.h") don't have to > include "migration/vmstate.h". > > Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org> > --- > Unresolved issues: > > https://www.mail-archive.com/qemu-devel@nongnu.org/msg721695.html > Peter: > > Does this definitely not put any data into the migration stream? > > We don't want to change what's on the wire for machines that > > use devices that start using this. (If it does by default, it > > would be easy to make the migration code special case the > > magic symbol to act like "no vmsd specified"). > > https://www.mail-archive.com/qemu-devel@nongnu.org/msg727634.html > Dave: > > I'd need to test it to be sure, but I think if we added a .needed > > to vmstate_no_state_to_migrate with a function that always returned > > false, then I think the stream would stay unchanged. Yes I still think you need that; if you only use this for base classes rather than devices themselves you're probably OK; but if you use it on a device I think you'll end up with an empty-state entry in the migration stream. Dave > --- > include/hw/qdev-core.h | 2 ++ > include/migration/vmstate.h | 1 + > hw/core/qdev.c | 3 +++ > migration/vmstate.c | 7 +++++++ > stubs/vmstate.c | 7 +++++++ > 5 files changed, 20 insertions(+) > > diff --git a/include/hw/qdev-core.h b/include/hw/qdev-core.h > index bafc311bfa1..d2c7a46e6a2 100644 > --- a/include/hw/qdev-core.h > +++ b/include/hw/qdev-core.h > @@ -140,6 +140,8 @@ struct DeviceClass { > const char *bus_type; > }; > > +extern const VMStateDescription *vmstate_qdev_no_state_to_migrate; > + > typedef struct NamedGPIOList NamedGPIOList; > > struct NamedGPIOList { > diff --git a/include/migration/vmstate.h b/include/migration/vmstate.h > index dda65c9987d..50559598eac 100644 > --- a/include/migration/vmstate.h > +++ b/include/migration/vmstate.h > @@ -197,6 +197,7 @@ struct VMStateDescription { > #if defined(CONFIG_USER_ONLY) > extern const VMStateDescription vmstate_user_mode_cpu_dummy; > #endif > +extern const VMStateDescription vmstate_no_state_to_migrate; > > extern const VMStateInfo vmstate_info_bool; > > diff --git a/hw/core/qdev.c b/hw/core/qdev.c > index cefc5eaa0a9..f0d0afd438d 100644 > --- a/hw/core/qdev.c > +++ b/hw/core/qdev.c > @@ -44,6 +44,9 @@ > static bool qdev_hot_added = false; > bool qdev_hot_removed = false; > > +const VMStateDescription *vmstate_qdev_no_state_to_migrate = > + &vmstate_no_state_to_migrate; > + > const VMStateDescription *qdev_get_vmsd(DeviceState *dev) > { > DeviceClass *dc = DEVICE_GET_CLASS(dev); > diff --git a/migration/vmstate.c b/migration/vmstate.c > index 05f87cdddc5..2c373774dfa 100644 > --- a/migration/vmstate.c > +++ b/migration/vmstate.c > @@ -20,6 +20,13 @@ > #include "qemu/error-report.h" > #include "trace.h" > > +const VMStateDescription vmstate_no_state_to_migrate = { > + .name = "empty-state", > + .fields = (VMStateField[]) { > + VMSTATE_END_OF_LIST() > + } > +}; > + > static int vmstate_subsection_save(QEMUFile *f, const VMStateDescription *vmsd, > void *opaque, JSONWriter *vmdesc); > static int vmstate_subsection_load(QEMUFile *f, const VMStateDescription *vmsd, > diff --git a/stubs/vmstate.c b/stubs/vmstate.c > index 8da777a1fb4..f561f9f39bd 100644 > --- a/stubs/vmstate.c > +++ b/stubs/vmstate.c > @@ -5,6 +5,13 @@ > const VMStateDescription vmstate_user_mode_cpu_dummy = {}; > #endif > > +const VMStateDescription vmstate_no_state_to_migrate = { > + .name = "empty-state", > + .fields = (VMStateField[]) { > + VMSTATE_END_OF_LIST() > + } > +}; > + > int vmstate_register_with_alias_id(VMStateIf *obj, > uint32_t instance_id, > const VMStateDescription *vmsd, > -- > 2.26.2 >
On Sun, 17 Jan 2021 at 19:25, Philippe Mathieu-Daudé <f4bug@amsat.org> wrote: > > Add vmstate_qdev_no_state_to_migrate, which is simply a > pointer to vmstate_no_state_to_migrate. This way all > qdev devices (including "hw/qdev-core.h") don't have to > include "migration/vmstate.h". > > Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org> > --- > Unresolved issues: > > https://www.mail-archive.com/qemu-devel@nongnu.org/msg721695.html > Peter: > > Does this definitely not put any data into the migration stream? > > We don't want to change what's on the wire for machines that > > use devices that start using this. (If it does by default, it > > would be easy to make the migration code special case the > > magic symbol to act like "no vmsd specified"). > > https://www.mail-archive.com/qemu-devel@nongnu.org/msg727634.html > Dave: > > I'd need to test it to be sure, but I think if we added a .needed > > to vmstate_no_state_to_migrate with a function that always returned > > false, then I think the stream would stay unchanged. > --- It should be easy to test -- just do a 'savevm' of a running system with a machine model that uses one of the devices that has been marked as "no state to migrate", then apply the patchseries, and see if 'loadvm' works or not. thanks -- PMM
diff --git a/include/hw/qdev-core.h b/include/hw/qdev-core.h index bafc311bfa1..d2c7a46e6a2 100644 --- a/include/hw/qdev-core.h +++ b/include/hw/qdev-core.h @@ -140,6 +140,8 @@ struct DeviceClass { const char *bus_type; }; +extern const VMStateDescription *vmstate_qdev_no_state_to_migrate; + typedef struct NamedGPIOList NamedGPIOList; struct NamedGPIOList { diff --git a/include/migration/vmstate.h b/include/migration/vmstate.h index dda65c9987d..50559598eac 100644 --- a/include/migration/vmstate.h +++ b/include/migration/vmstate.h @@ -197,6 +197,7 @@ struct VMStateDescription { #if defined(CONFIG_USER_ONLY) extern const VMStateDescription vmstate_user_mode_cpu_dummy; #endif +extern const VMStateDescription vmstate_no_state_to_migrate; extern const VMStateInfo vmstate_info_bool; diff --git a/hw/core/qdev.c b/hw/core/qdev.c index cefc5eaa0a9..f0d0afd438d 100644 --- a/hw/core/qdev.c +++ b/hw/core/qdev.c @@ -44,6 +44,9 @@ static bool qdev_hot_added = false; bool qdev_hot_removed = false; +const VMStateDescription *vmstate_qdev_no_state_to_migrate = + &vmstate_no_state_to_migrate; + const VMStateDescription *qdev_get_vmsd(DeviceState *dev) { DeviceClass *dc = DEVICE_GET_CLASS(dev); diff --git a/migration/vmstate.c b/migration/vmstate.c index 05f87cdddc5..2c373774dfa 100644 --- a/migration/vmstate.c +++ b/migration/vmstate.c @@ -20,6 +20,13 @@ #include "qemu/error-report.h" #include "trace.h" +const VMStateDescription vmstate_no_state_to_migrate = { + .name = "empty-state", + .fields = (VMStateField[]) { + VMSTATE_END_OF_LIST() + } +}; + static int vmstate_subsection_save(QEMUFile *f, const VMStateDescription *vmsd, void *opaque, JSONWriter *vmdesc); static int vmstate_subsection_load(QEMUFile *f, const VMStateDescription *vmsd, diff --git a/stubs/vmstate.c b/stubs/vmstate.c index 8da777a1fb4..f561f9f39bd 100644 --- a/stubs/vmstate.c +++ b/stubs/vmstate.c @@ -5,6 +5,13 @@ const VMStateDescription vmstate_user_mode_cpu_dummy = {}; #endif +const VMStateDescription vmstate_no_state_to_migrate = { + .name = "empty-state", + .fields = (VMStateField[]) { + VMSTATE_END_OF_LIST() + } +}; + int vmstate_register_with_alias_id(VMStateIf *obj, uint32_t instance_id, const VMStateDescription *vmsd,