qemu-e2k/docs/xen-save-devices-state.txt
Stefano Stabellini a7ae8355b4 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>
2012-03-19 18:21:00 +00:00

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= 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