Re: [Qemu-devel] [PATCH 1/1] s390x/migration: Introduce 2.4 machine

[Juan Quintela <quintela@redhat.com>]

Christian Borntraeger <borntraeger@de.ibm.com> wrote:
> Am 01.07.2015 um 11:56 schrieb Juan Quintela:
>> Christian Borntraeger <borntraeger@de.ibm.com> wrote:
>> 
>> First of all
>> 
>> Reviewed-by: Juan Quintela <quintela@redhat.com>
>> 
>> For the patch.
>> 
>> But one said that, I don't agree with the commint text.
>
> So let's just drop this sentence
>>> While one can argue that section footer should be enabled
>>> explicitely for new versions instead of disabled for old ones,
>
> And rephrase to
>
> "
> This pinpoints to a problem of s390-ccw-machines: it needs to
> be versioned to allow common code changes to add compat handling.
> " 
>
>
>
> Conny, want me to resend or can you fixup the patch description when
> taking this patch?


>
>> 
>> 
>>> The section footer changes commit f68945d42bab ("Add a protective
>>> section footer") and commit 37fb569c0198 ("Disable section footers
>>> on older machine types") broke migration for any non-versioned
>>> machines.
>> 
>> If broke migration for 2.4 -> 2.3 for machines that don't care about
>> compatibility.  If they care, they are versioned O:-)  Right now ppc &
>> x86.  I guess that s390 and arm will follow in due curse.
>
> yes. That is what my 2nd sentence says: we are not versioned and that is
> the main issue to solve.

You do it, so you are well.  Thanks.

>> was good for any reason, normal devices do changes, and then x86 try to
>> fix the pieces after the fact.  That is going to continue, just that now
>> more architectures care, and then we should detect this kind of problems
>> much earlier.
>> 
>>> Let's introduce a version scheme for s390-ccw-virtio machines.
>>> We will use the old s390-ccw-virtio name as alias to the latest
>>> version as all existing libvirt XML for the ccw type were expanded
>>> by libvirt to that name.
>>>
>>> The only downside of this patch is, that the old alias s390-ccw
>>> will no longer be available as machines can have only one alias,
>>> but it should not really matter.
>> 
>> Should we change to a list?
>
> list of aliases? Why not, we would use it.

Anyone for machine definitions reading this?  More people need/wants it?

Later, Juan