Steve Sistare <steven.sist...@oracle.com> writes:
> Clarify qapi for cpr-reboot migration mode, and add vfio support.
The patch only affects documentation, but that's less than clear from
the commit message. Suggest
Improve documentation for migration mode @cpr-reboot. In particular,
document VFIO support.
> Signed-off-by: Steve Sistare <steven.sist...@oracle.com>
> ---
> qapi/migration.json | 35 ++++++++++++++++++++++-------------
> 1 file changed, 22 insertions(+), 13 deletions(-)
>
> diff --git a/qapi/migration.json b/qapi/migration.json
> index 5a565d9..0990297 100644
> --- a/qapi/migration.json
> +++ b/qapi/migration.json
> @@ -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.
These two sentences apply to any migration mode, don't they? Just
checking I understand.
> +#
> +# 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.
Hmm, doesn't normal migration also support migrating to a newer QEMU?
> +#
> +# 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.
"Must not modify the contents of the guest block devices"?
> +#
> +# This mode supports vfio devices provided the user first puts the guest
"VFIO devices"
> +# 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
Typo: "be be non-volatile"
Suggest "the shared memory must persist"
> +# it with a dax device.
> +#
> +# (since 8.2)
> ##
> { 'enum': 'MigMode',
> 'data': [ 'normal', 'cpr-reboot' ] }
Thanks for adjusting indentation to conform to conventions. Please
additionally reflow the text to limit line length to 70 characters.
