On Fri, Jun 06, 2025 at 05:23:18PM -0300, Fabiano Rosas wrote:
> Peter Xu <pet...@redhat.com> writes:
>
> > On Mon, Jun 02, 2025 at 10:38:08PM -0300, Fabiano Rosas wrote:
> >> Allow the migrate and migrate_incoming commands to pass the migration
> >> configuration options all at once, dispensing the use of
> >> migrate-set-parameters and migrate-set-capabilities.
> >>
> >> The motivation of this is to simplify the interface with the
> >> management layer and avoid the usage of several command invocations to
> >> configure a migration. It also avoids stale parameters from a previous
> >> migration to influence the current migration.
> >>
> >> The options that are changed during the migration can still be set
> >> with the existing commands.
> >>
> >> The order of precedence is:
> >>
> >> 'config' argument > -global cmdline > defaults (migration_properties)
> >
> > Could we still keep the QMP migrate-set-parameters values?
> >
> > 'config' argument > QMP setups using migrate-set-parameters >
> > -global cmdline > defaults (migration_properties)
> >
>
> That's the case. I failed to mention it in the commit message. IOW it
> behaves just like today, but the new 'config' way takes precedence over
> all.
Referring to below chunk of code:
[...]
> >> +bool migrate_params_override(MigrationState *s, MigrationParameters *new,
> >> + Error **errp)
> >> +{
> >> + ERRP_GUARD();
> >> +
> >> + assert(bql_locked());
> >> +
> >> + /* reset to default parameters */
> >> + migrate_params_apply(&s->defaults);
IIUC here it'll reset all global parameters using the initial defaults
first, then apply the "config" specified in "migrate" QMP command?
I think there're actually two separate questions to be asked, to make it
clearer, they are:
(1) Whether we should allow QMP "migrate" 'config' parameter to overwrite
global setup?
(2) Whether we should allow previous QMP global setup to be used even if
QMP "migrate" provided 'config' parameter?
So IIUC the patch does (1) YES (2) NO, while what I think might be more
intuitive is (1) NO (2) YES.
> >> +
> >> + /* overwrite with the new ones */
> >> + qmp_migrate_set_parameters(new, errp);
> >> + if (*errp) {
> >> + return false;
> >> + }
> >> +
> >> + return true;
> >> +}
--
Peter Xu
