From: Marc-André Lureau <marcandre.lureau@redhat.com>

Add a "ramfb-dev" section whenever "x-migrate" is turned on. Turn it off
by default on machines <= 8.1 for compatibility reasons.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
---
 hw/core/machine.c             |  4 +++-
 hw/display/ramfb-standalone.c | 27 +++++++++++++++++++++++++++
 2 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/hw/core/machine.c b/hw/core/machine.c
index 281ef0dccd..e4361e3d48 100644
--- a/hw/core/machine.c
+++ b/hw/core/machine.c
@@ -31,7 +31,9 @@
 #include "hw/virtio/virtio-net.h"
 #include "audio/audio.h"
 
-GlobalProperty hw_compat_8_1[] = {};
+GlobalProperty hw_compat_8_1[] = {
+    { "ramfb", "x-migrate", "off" },
+};
 const size_t hw_compat_8_1_len = G_N_ELEMENTS(hw_compat_8_1);
 
 GlobalProperty hw_compat_8_0[] = {
diff --git a/hw/display/ramfb-standalone.c b/hw/display/ramfb-standalone.c
index 8c0094397f..a96e7ebcd9 100644
--- a/hw/display/ramfb-standalone.c
+++ b/hw/display/ramfb-standalone.c
@@ -1,4 +1,5 @@
 #include "qemu/osdep.h"
+#include "migration/vmstate.h"
 #include "qapi/error.h"
 #include "qemu/module.h"
 #include "hw/loader.h"
@@ -15,6 +16,7 @@ struct RAMFBStandaloneState {
     SysBusDevice parent_obj;
     QemuConsole *con;
     RAMFBState *state;
+    bool migrate;
 };
 
 static void display_update_wrapper(void *dev)
@@ -40,14 +42,39 @@ static void ramfb_realizefn(DeviceState *dev, Error **errp)
     ramfb->state = ramfb_setup(errp);
 }
 
+static bool migrate_needed(void *opaque)
+{
+    RAMFBStandaloneState *ramfb = RAMFB(opaque);
+
+    return ramfb->migrate;
+}
+
+static const VMStateDescription ramfb_dev_vmstate = {
+    .name = "ramfb-dev",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .needed = migrate_needed,
+    .fields = (VMStateField[]) {
+        VMSTATE_STRUCT_POINTER(state, RAMFBStandaloneState, ramfb_vmstate, RAMFBState),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+static Property ramfb_properties[] = {
+    DEFINE_PROP_BOOL("x-migrate", RAMFBStandaloneState, migrate,  true),
+    DEFINE_PROP_END_OF_LIST(),
+};
+
 static void ramfb_class_initfn(ObjectClass *klass, void *data)
 {
     DeviceClass *dc = DEVICE_CLASS(klass);
 
     set_bit(DEVICE_CATEGORY_DISPLAY, dc->categories);
+    dc->vmsd = &ramfb_dev_vmstate;
     dc->realize = ramfb_realizefn;
     dc->desc = "ram framebuffer standalone device";
     dc->user_creatable = true;
+    device_class_set_props(dc, ramfb_properties);
 }
 
 static const TypeInfo ramfb_info = {
-- 
2.41.0

On 10/5/23 13:30, marcandre.lureau@redhat.com wrote:
> From: Marc-André Lureau <marcandre.lureau@redhat.com>
> 
> Add a "ramfb-dev" section whenever "x-migrate" is turned on. Turn it off
> by default on machines <= 8.1 for compatibility reasons.
> 
> Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
> ---
>  hw/core/machine.c             |  4 +++-
>  hw/display/ramfb-standalone.c | 27 +++++++++++++++++++++++++++
>  2 files changed, 30 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/core/machine.c b/hw/core/machine.c
> index 281ef0dccd..e4361e3d48 100644
> --- a/hw/core/machine.c
> +++ b/hw/core/machine.c
> @@ -31,7 +31,9 @@
>  #include "hw/virtio/virtio-net.h"
>  #include "audio/audio.h"
>  
> -GlobalProperty hw_compat_8_1[] = {};
> +GlobalProperty hw_compat_8_1[] = {
> +    { "ramfb", "x-migrate", "off" },
> +};
>  const size_t hw_compat_8_1_len = G_N_ELEMENTS(hw_compat_8_1);
>  
>  GlobalProperty hw_compat_8_0[] = {
> diff --git a/hw/display/ramfb-standalone.c b/hw/display/ramfb-standalone.c
> index 8c0094397f..a96e7ebcd9 100644
> --- a/hw/display/ramfb-standalone.c
> +++ b/hw/display/ramfb-standalone.c
> @@ -1,4 +1,5 @@
>  #include "qemu/osdep.h"
> +#include "migration/vmstate.h"
>  #include "qapi/error.h"
>  #include "qemu/module.h"
>  #include "hw/loader.h"
> @@ -15,6 +16,7 @@ struct RAMFBStandaloneState {
>      SysBusDevice parent_obj;
>      QemuConsole *con;
>      RAMFBState *state;
> +    bool migrate;
>  };
>  
>  static void display_update_wrapper(void *dev)
> @@ -40,14 +42,39 @@ static void ramfb_realizefn(DeviceState *dev, Error **errp)
>      ramfb->state = ramfb_setup(errp);
>  }
>  
> +static bool migrate_needed(void *opaque)
> +{
> +    RAMFBStandaloneState *ramfb = RAMFB(opaque);
> +
> +    return ramfb->migrate;
> +}
> +
> +static const VMStateDescription ramfb_dev_vmstate = {
> +    .name = "ramfb-dev",
> +    .version_id = 1,
> +    .minimum_version_id = 1,
> +    .needed = migrate_needed,
> +    .fields = (VMStateField[]) {
> +        VMSTATE_STRUCT_POINTER(state, RAMFBStandaloneState, ramfb_vmstate, RAMFBState),
> +        VMSTATE_END_OF_LIST()
> +    }
> +};
> +
> +static Property ramfb_properties[] = {
> +    DEFINE_PROP_BOOL("x-migrate", RAMFBStandaloneState, migrate,  true),
> +    DEFINE_PROP_END_OF_LIST(),
> +};
> +
>  static void ramfb_class_initfn(ObjectClass *klass, void *data)
>  {
>      DeviceClass *dc = DEVICE_CLASS(klass);
>  
>      set_bit(DEVICE_CATEGORY_DISPLAY, dc->categories);
> +    dc->vmsd = &ramfb_dev_vmstate;
>      dc->realize = ramfb_realizefn;
>      dc->desc = "ram framebuffer standalone device";
>      dc->user_creatable = true;
> +    device_class_set_props(dc, ramfb_properties);
>  }
>  
>  static const TypeInfo ramfb_info = {

Identical to v3, which I reviewed, so:

Reviewed-by: Laszlo Ersek <lersek@redhat.com>