Introduce "xen-save-devices-state"

- add an "is_ram" flag to SaveStateEntry;

- register_savevm_live sets is_ram for live_savevm devices;

- introduce a "xen-save-devices-state" QAPI command that can be used to save
the state of all devices, but not the RAM or the block devices of the
VM.

Changes in v8:

- rename save-devices-state to xen-save-devices-state.

Changes in v7:

- rename save_devices to save-devices-state.

Changes in v6:

- remove the is_ram parameter from register_savevm_live and sets is_ram
if the device is a live_savevm device;

- introduce save_devices as a QAPI command, write a better description
for it;

- fix CODING_STYLE;

- introduce a new doc to explain the save format used by save_devices.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Reviewed-by: Anthony Liguori <aliguori@us.ibm.com>
Acked-by: Luiz Capitulino <lcapitulino@redhat.com>

1 files changed, 34 insertions, 0 deletions

diff --git a/docs/xen-save-devices-state.txt b/docs/xen-save-devices-state.txt
new file mode 100644
index 0000000..92e08db
--- /dev/null
+++ b/docs/xen-save-devices-state.txt
@@ -0,0 +1,34 @@
+= Save Devices =
+
+QEMU has code to load/save the state of the guest that it is running.
+These are two complementary operations.  Saving the state just does
+that, saves the state for each device that the guest is running.
+
+These operations are normally used with migration (see migration.txt),
+however it is also possible to save the state of all devices to file,
+without saving the RAM or the block devices of the VM.
+
+This operation is called "xen-save-devices-state" (see
+QMP/qmp-commands.txt)
+
+
+The binary format used in the file is the following:
+
+
+-------------------------------------------
+
+32 bit big endian: QEMU_VM_FILE_MAGIC
+32 bit big endian: QEMU_VM_FILE_VERSION
+
+for_each_device
+{
+    8 bit:              QEMU_VM_SECTION_FULL
+    32 bit big endian:  section_id
+    8 bit:              idstr (ID string) length
+    string:             idstr (ID string)
+    32 bit big endian:  instance_id
+    32 bit big endian:  version_id
+    buffer:             device specific data
+}
+
+8 bit: QEMU_VM_EOF