xref: /qemu/docs/xen-save-devices-state.txt (revision 1ef1cee7)
1= Save Devices =
2
3QEMU has code to load/save the state of the guest that it is running.
4These are two complementary operations.  Saving the state just does
5that, saves the state for each device that the guest is running.
6
7These operations are normally used with migration (see migration.txt),
8however it is also possible to save the state of all devices to file,
9without saving the RAM or the block devices of the VM.
10
11The save operation is available as QMP command xen-save-devices-state.
12
13
14The binary format used in the file is the following:
15
16
17-------------------------------------------
18
1932 bit big endian: QEMU_VM_FILE_MAGIC
2032 bit big endian: QEMU_VM_FILE_VERSION
21
22for_each_device
23{
24    8 bit:              QEMU_VM_SECTION_FULL
25    32 bit big endian:  section_id
26    8 bit:              idstr (ID string) length
27    string:             idstr (ID string)
28    32 bit big endian:  instance_id
29    32 bit big endian:  version_id
30    buffer:             device specific data
31}
32
338 bit: QEMU_VM_EOF
34