Re: [Qemu-devel] [PATCH 2/3] migrate: Share common MigrationParameters struct

[Juan Quintela <quintela@redhat.com>]

Eric Blake <eblake@redhat.com> wrote:
> It is rather verbose, and slightly error-prone, to repeat
> the same set of parameters for input (migrate-set-parameters)
> as for output (query-migrate-parameters), where the only
> difference is whether the members are optional.  We can just
> document that the optional members will always be present
> on output, and then share a common struct between both
> commands.  The next patch can then reduce the amount of
> code needed on input.
>
> Also, we made a mistake in qemu 2.7 of returning an empty
> string during 'query-migrate-parameters' when there is no
> TLS, rather than omitting TLS details entirely.  Technically,
> this change risks breaking any 2.7 client that is hard-coded
> to expect the parameter's existence; on the other hand, clients
> that are portable to 2.6 already must be prepared for those
> members to not be present.
>
> And this gets rid of yet one more place where the QMP output
> visitor is silently converting a NULL string into "" (which
> is a hack I ultimately want to kill off).
>
> Signed-off-by: Eric Blake <eblake@redhat.com>

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