Re: [PATCH V2 5/6] cpr: reboot mode

[Juan Quintela <quintela@redhat.com>]

Steve Sistare <steven.sistare@oracle.com> wrote:
> Add the cpr-reboot migration mode.  Usage:
>
> $ qemu-system-$arch -monitor stdio ...
> QEMU 8.1.50 monitor - type 'help' for more information
> (qemu) migrate_set_capability x-ignore-shared on
> (qemu) migrate_set_parameter mode cpr-reboot
> (qemu) migrate -d file:vm.state
> (qemu) info status
> VM status: paused (postmigrate)
> (qemu) quit
>
> $ qemu-system-$arch -monitor stdio -incoming defer ...
> QEMU 8.1.50 monitor - type 'help' for more information
> (qemu) migrate_set_capability x-ignore-shared on
> (qemu) migrate_set_parameter mode cpr-reboot
> (qemu) migrate_incoming file:vm.state
> (qemu) info status
> VM status: running
>
> In this mode, 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.
>
> Signed-off-by: Steve Sistare <steven.sistare@oracle.com>

Reviewed-by: Juan Quintela <quintela@redhat.com>