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From: Markus Armbruster <armbru@redhat.com>
To: Eduardo Habkost <ehabkost@redhat.com>
Cc: "Daniel P. Berrangé" <berrange@redhat.com>,
	"Juan Quintela" <quintela@redhat.com>,
	qemu-devel@nongnu.org,
	"Dr. David Alan Gilbert" <dgilbert@redhat.com>,
	"Paolo Bonzini" <pbonzini@redhat.com>,
	"Vitaly Kuznetsov" <vkuznets@redhat.com>
Subject: Re: [PATCH RFC] migration: warn about non-migratable configurations unless '--no-migration' was specified
Date: Sat, 17 Apr 2021 11:33:24 +0200	[thread overview]
Message-ID: <87tuo51cij.fsf@dusky.pond.sub.org> (raw)
In-Reply-To: <20210416162801.zluqlbvyipoanedw@habkost.net> (Eduardo Habkost's message of "Fri, 16 Apr 2021 12:28:01 -0400")

Eduardo Habkost <ehabkost@redhat.com> writes:

[...]
> I would make live migration policy an enum, just to make sure
> we are explicit about the requirements:
>
> - UNKNOWN: this is the current state in QEMU 6.0, where we don't
>   really know what the user expects.
>   This can be the default on existing versioned machine types,
>   just for compatibility.
>   I suggest making this print warnings for every migration
>   blocker (like this patch does).
>   I suggest deprecating this behavior as soon as we can.
>
> - PREFERRED: try to make the VM migratable when possible, but
>   don't print a warning or error out if migration is blocked.
>   This seems to be the behavior expected by libvirt today.
>
> - NOT_NEEDED: live migration is not needed, and QEMU is free to
>   enable features that block live migration or change guest ABI.
>   We can probably make this the default on machine types that
>   never supported live migration.
>
> - REQUIRED: live migration is required, and adding a migration
>   blocker would be a fatal error.

To be precise: would be an error.  During initial configuration, the
error is fatal, i.e. exit(1).  In a QMP command, it's not; only the
command fails.

>   This is already implemented by --only-migratable.
>   I suggest making this the default on versioned machine types
>   after a few releases, and after deprecating UNKNOWN.

Makes sense to me (but of course we can still quibble about the names).



  reply	other threads:[~2021-04-17  9:34 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-15 15:44 [PATCH RFC] migration: warn about non-migratable configurations unless '--no-migration' was specified Vitaly Kuznetsov
2021-04-15 16:04 ` Daniel P. Berrangé
2021-04-15 16:30   ` Eduardo Habkost
2021-04-15 16:40     ` Daniel P. Berrangé
2021-04-15 17:07       ` Daniel P. Berrangé
2021-04-15 17:28   ` Dr. David Alan Gilbert
2021-04-16  7:33     ` Vitaly Kuznetsov
2021-04-16 16:28       ` Eduardo Habkost
2021-04-17  9:33         ` Markus Armbruster [this message]
2021-04-19 16:42         ` Daniel P. Berrangé
2021-04-19 16:48           ` Eduardo Habkost
2021-04-19 17:11         ` Dr. David Alan Gilbert
2021-04-19 17:15           ` Daniel P. Berrangé
2021-04-19 17:17             ` Daniel P. Berrangé
2021-04-19 18:47               ` Dr. David Alan Gilbert
2021-04-19 19:32                 ` Eduardo Habkost
2021-04-20 11:51                   ` Dr. David Alan Gilbert
2021-04-20 13:48                     ` Eduardo Habkost
2021-04-20 14:10                       ` Dr. David Alan Gilbert
2021-04-20 14:15                         ` Daniel P. Berrangé
2021-04-20 15:20                         ` Eduardo Habkost
2021-04-17  9:35 ` Markus Armbruster
2021-04-19  7:26   ` Markus Armbruster
2021-04-19 15:46   ` Markus Armbruster
2021-04-18 15:53 ` Peter Maydell
2021-04-19 16:28   ` Eduardo Habkost
2021-04-19 16:37     ` Daniel P. Berrangé

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