@@ -636,19 +636,28 @@
#
# @normal: the original form of migration. (since 8.2)
#
-# @cpr-reboot: The migrate command saves state to a file, allowing one to
-# quit qemu, reboot to an updated kernel, and restart an updated
-# version of qemu. The caller must specify a migration URI
-# that writes to and reads from a file. Unlike normal mode,
-# the use of certain local storage options does not block the
-# migration, but the caller must not modify guest block devices
-# between the quit and restart. To avoid saving guest RAM to the
-# file, the memory backend must be shared, and the @x-ignore-shared
-# migration capability must be set. Guest RAM must be non-volatile
-# across reboot, such as by backing it with a dax device, but this
-# is not enforced. The restarted qemu arguments must match those
-# used to initially start qemu, plus the -incoming option.
-# (since 8.2)
+# @cpr-reboot: The migrate command stops the VM and saves state to the URI.
+# After quitting qemu, the user resumes by running qemu -incoming.
+#
+# This mode allows the user to quit qemu, and restart an updated version
+# of qemu. The user may even update and reboot the OS before restarting,
+# as long as the URI persists across a reboot.
+#
+# Unlike normal mode, the use of certain local storage options does not
+# block the migration, but the user must not modify guest block devices
+# between the quit and restart.
+#
+# This mode supports vfio devices provided the user first puts the guest
+# in the suspended runstate, such as by issuing guest-suspend-ram to the
+# qemu guest agent.
+#
+# Best performance is achieved when the memory backend is shared and the
+# @x-ignore-shared migration capability is set, but this is not required.
+# Further, if the user reboots before restarting such a configuration, the
+# shared backend must be be non-volatile across reboot, such as by backing
+# it with a dax device.
+#
+# (since 8.2)
##
{ 'enum': 'MigMode',
'data': [ 'normal', 'cpr-reboot' ] }