[PATCH v5 1/3] ramfb: add migration support

[marcandre . lureau]

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

Implementing RAMFB migration is quite straightforward. One caveat is to
treat the whole RAMFBCfg as a blob, since that's what is exposed to the
guest directly. This avoid having to fiddle with endianness issues if we
were to migrate fields individually as integers.

The devices using RAMFB will have to include ramfb_vmstate in their
migration description.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
---
 include/hw/display/ramfb.h |  4 ++++
 hw/display/ramfb.c         | 19 +++++++++++++++++++
 2 files changed, 23 insertions(+)

diff --git a/include/hw/display/ramfb.h b/include/hw/display/ramfb.h
index b33a2c467b..a7e0019144 100644
--- a/include/hw/display/ramfb.h
+++ b/include/hw/display/ramfb.h
@@ -1,11 +1,15 @@
 #ifndef RAMFB_H
 #define RAMFB_H
 
+#include "migration/vmstate.h"
+
 /* ramfb.c */
 typedef struct RAMFBState RAMFBState;
 void ramfb_display_update(QemuConsole *con, RAMFBState *s);
 RAMFBState *ramfb_setup(Error **errp);
 
+extern const VMStateDescription ramfb_vmstate;
+
 /* ramfb-standalone.c */
 #define TYPE_RAMFB_DEVICE "ramfb"
 
diff --git a/hw/display/ramfb.c b/hw/display/ramfb.c
index c2b002d534..477ef7272a 100644
--- a/hw/display/ramfb.c
+++ b/hw/display/ramfb.c
@@ -28,6 +28,8 @@ struct QEMU_PACKED RAMFBCfg {
     uint32_t stride;
 };
 
+typedef struct RAMFBCfg RAMFBCfg;
+
 struct RAMFBState {
     DisplaySurface *ds;
     uint32_t width, height;
@@ -116,6 +118,23 @@ void ramfb_display_update(QemuConsole *con, RAMFBState *s)
     dpy_gfx_update_full(con);
 }
 
+static int ramfb_post_load(void *opaque, int version_id)
+{
+    ramfb_fw_cfg_write(opaque, 0, 0);
+    return 0;
+}
+
+const VMStateDescription ramfb_vmstate = {
+    .name = "ramfb",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .post_load = ramfb_post_load,
+    .fields = (VMStateField[]) {
+        VMSTATE_BUFFER_UNSAFE(cfg, RAMFBState, 0, sizeof(RAMFBCfg)),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
 RAMFBState *ramfb_setup(Error **errp)
 {
     FWCfgState *fw_cfg = fw_cfg_find();
-- 
2.41.0