devel/migration/CPR.rst

8 cpr-reboot is the only available mode.
15 CPR unconditionally stops VM execution before memory is saved, and
18 cpr-reboot mode
19 ---------------
23 resumes by running QEMU with the ``-incoming`` option.  Because the
27 Guest RAM can be saved in place if backed by shared memory, or can be
31 After state and memory are saved, the user may update userland host
33 the RAM is backed by persistent shared memory, such as a DAX device,
38 ``guest-suspend-ram`` command to the QEMU guest agent.  The agent
39 must be pre-installed in the guest, and the guest must support
47 It is recommended that guest RAM be backed with some type of shared
48 memory, such as ``memory-backend-file,share=on``, and that the
49 ``x-ignore-shared`` capability be set.  This combination allows memory
54   * Set the migration mode parameter to ``cpr-reboot``.
55   * Set the ``x-ignore-shared`` capability if desired.
63   * Start QEMU with the ``-incoming defer`` option.
64   * Set the migration mode parameter to ``cpr-reboot``.
65   * Set the ``x-ignore-shared`` capability if desired.
66   * Issue the ``migrate-incoming`` command.
74   # qemu-kvm -monitor stdio
75   -object memory-backend-file,id=ram0,size=4G,mem-path=/dev/dax0.0,align=2M,share=on -m 4G
80   (qemu) migrate_set_parameter mode cpr-reboot
81   (qemu) migrate_set_capability x-ignore-shared on
82   (qemu) migrate -d file:vm.state
92   # qemu-kvm ... -incoming defer
95   (qemu) migrate_set_parameter mode cpr-reboot
96   (qemu) migrate_set_capability x-ignore-shared on
105   # qemu-kvm -monitor stdio
106   -object memory-backend-file,id=ram0,size=4G,mem-path=/dev/dax0.0,align=2M,share=on -m 4G
107   -device vfio-pci, ...
108   -chardev socket,id=qga0,path=qga.sock,server=on,wait=off
109   -device virtserialport,chardev=qga0,name=org.qemu.guest_agent.0
115   # echo '{"execute":"guest-suspend-ram"}' | ncat --send-only -U qga.sock
119   (qemu) migrate_set_parameter mode cpr-reboot
120   (qemu) migrate_set_capability x-ignore-shared on
121   (qemu) migrate -d file:vm.state
131   # qemu-kvm ... -incoming defer
134   (qemu) migrate_set_parameter mode cpr-reboot
135   (qemu) migrate_set_capability x-ignore-shared on
146 cpr-reboot mode may not be used with postcopy, background-snapshot,