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From: Juan Quintela <quintela@redhat.com>
In-Reply-To: <20170628190616.GN12152@localhost.localdomain> (Eduardo Habkost's
	message of "Wed, 28 Jun 2017 16:06:16 -0300")
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Reply-To: quintela@redhat.com
Date: Thu, 29 Jun 2017 00:42:56 +0200
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Subject: Re: [Qemu-devel] [PATCH v6 09/10] migration: merge
 enforce_config_section somewhat
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To: Eduardo Habkost <ehabkost@redhat.com>
Cc: Peter Xu <peterx@redhat.com>, qemu-devel@nongnu.org, Laurent Vivier <lvivier@redhat.com>, Eric Blake <eblake@redhat.com>, Markus Armbruster <armbru@redhat.com>, "Dr . David Alan Gilbert" <dgilbert@redhat.com>

Eduardo Habkost <ehabkost@redhat.com> wrote:

>
> So, this is a case where a user-provided config option (-machine
> enforce-config-section) should trigger a different default in another
> class (migration.send-configuration).
>
> Also, the new default triggered by -machine has a very specific
> priority:
>
> * AccelClass::global_props must not override "-machine enforce-config-section=on"
> * MachineClass::compat_props must not override
>   "-machine enforce-config-section=on"
>
> We must also decide in advance what should be result of:
> * "-machine enforce-config-section=on -global migration.send-configuration=off"
> * "-machine enforce-config-section=off -global migration.send-configuration=on"
> * "-global migration.send-configuration=off -machine enforce-config-section=off"
> * "-global migration.send-configuration=on -machine enforce-config-section=on"

BOOM!!!!!

We use old configuration or new one.


>
> I'm not sure what we should decide about these 4 cases above, but I
> believe it would be safer to encode that decision at the same place we
> handle the priority between accel/machine/user globals:
> register_global_properties() at vl.c.
>
>
> Or maybe this extra complexity is a sign that we shouldn't try to add
> extra magic to make -machine affect the "migration" object properties,
> and keep the existing machine->enforce_config_section check in the
> migration code?  I'm not sure.

Not sure there either.  I preffer doing it in a single place, but I am
not the expert here.

Later, Juan.