Re: [Qemu-devel] [PATCH 5/7] Switch migrate_set_speed() to take an 'o' argument rather than a float.

[Markus Armbruster]

[cc: Anthony, please review the proposed incompatible change of the
human monitor]

address@hidden writes:

> From: Jes Sorensen <address@hidden>
>
> Signed-off-by: Jes Sorensen <address@hidden>
> ---
>  hmp-commands.hx |    2 +-
>  migration.c     |    4 ++--
>  2 files changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/hmp-commands.hx b/hmp-commands.hx
> index 81999aa..95bdb91 100644
> --- a/hmp-commands.hx
> +++ b/hmp-commands.hx
> @@ -754,7 +754,7 @@ ETEXI
>  
>      {
>          .name       = "migrate_set_speed",
> -        .args_type  = "value:f",
> +        .args_type  = "value:o",
>          .params     = "value",
>          .help       = "set maximum speed (in bytes) for migrations",
>          .user_print = monitor_user_noop,
> diff --git a/migration.c b/migration.c
> index 468d517..9ee8b17 100644
> --- a/migration.c
> +++ b/migration.c
> @@ -132,10 +132,10 @@ int do_migrate_cancel(Monitor *mon, const QDict *qdict, 
> QObject **ret_data)
>  
>  int do_migrate_set_speed(Monitor *mon, const QDict *qdict, QObject 
> **ret_data)
>  {
> -    double d;
> +    int64_t d;
>      FdMigrationState *s;
>  
> -    d = qdict_get_double(qdict, "value");
> +    d = qdict_get_int(qdict, "value");
>      d = MAX(0, MIN(UINT32_MAX, d));
>      max_throttle = d;

As noted before, this is an incompatible change of the human monitor
command: unit now defaults to 'M'.  This must be noted *prominently* in
the commit message.  Best in the subject.

Incompatible changes can break tools.  Quick grep of libvirt:

src/qemu/qemu_monitor_json.c:    cmd = 
qemuMonitorJSONMakeCommand("migrate_set_speed",
src/qemu/qemu_monitor_text.c:    if (virAsprintf(&cmd, "migrate_set_speed 
%lum", bandwidth) < 0) {

Looks like we're safe here.

Anthony, is this incompatibility okay?

Help should be updated in the same patch; please squash 6/7 into 5/7.