Re: [PATCH V4 09/19] migration: incoming channel

[Peter Xu]

On Mon, Dec 09, 2024 at 01:12:25PM +0100, Markus Armbruster wrote:
> >>> @@ -2730,7 +2761,7 @@ void qmp_x_exit_preconfig(Error **errp)
> >>>       if (incoming) {
> >>>           Error *local_err = NULL;
> >>>           if (strcmp(incoming, "defer") != 0) {
> >>> -            qmp_migrate_incoming(incoming, false, NULL, true, true,
> >>> +            qmp_migrate_incoming(NULL, true, incoming_channels, true, 
> >>> true,
> >>>                                    &local_err);
> >>
> >> You move the parsing of legacy URI from within qmp_migrate_incoming()
> >> into incoming_option_parse().
> >>
> >> The alternative is not to parse it in incoming_option_parse(), but pass
> >> it to qmp_migrate_incoming() like this:
> >>
> >>                 qmp_migrate_incoming(incoming, !incoming, 
> >> incoming_channels,
> >>                                      true, true, &local_err);
> >
> > Sure, I can tweak that, but I need to define an additional incoming_uri 
> > variable:
> >     qmp_migrate_incoming(incoming_uri, !!incoming_channels, 
> > incoming_channels, ...
> >
> > Only one of incoming_uri and incoming_channels can be non-NULL (checked in
> > qemu_start_incoming_migration).
> >
> > Would you prefer I continue down this path, or revert to the previous 
> > -cpr-uri
> > option?  I made this change to make the incoming interface look more like 
> > the
> > V4 outgoing interface, in which the user adds a cpr channel to the migrate 
> > command
> > channels.
> 
> I'm not sure.  Peter, what do you think?

For this specific question, I prefer reusing -incoming rather than going
back to -cpr-uri.

We should have discussed about this in the previous spin of a follow up
discussion, using -incoming for cpr channels seems to always be preferred.

https://lore.kernel.org/qemu-devel/Zz4NqcTDK73MKOaa@redhat.com/

At that time, the concern from Dan was not reusing the JSON format or
design the CLI's own format.  That was always based on reusing -incoming.

In this patch it's already reusing the JSON for the CPR port, which looks
all good from that POV.  OTOH, I don't yet have any preference on the impl
of how QEMU should do the internal parsing of such JSON string / legacy
URIs.

Thanks,

-- 
Peter Xu