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From: Laszlo Ersek <lersek@redhat.com>
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Date: Thu, 18 Feb 2016 20:32:03 +0100
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Subject: Re: [Qemu-devel] Unable to migrate pc-i440fx-2.4 KVM guest from
 QEMU 2.5.0 to QEMU 2.4.1
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To: Paolo Bonzini <pbonzini@redhat.com>, Alexandre DERUMIER <aderumier@odiso.com>, qemu-devel <qemu-devel@nongnu.org>

On 02/18/16 19:24, Paolo Bonzini wrote:
> 
> 
> On 18/02/2016 18:54, Alexandre DERUMIER wrote:
>> Hi,
>>
>> I (and promox users) have same problem than this bugreport
>>
>> https://bugs.launchpad.net/qemu/+bug/1536487
>> https://forum.proxmox.com/threads/cant-live-migrate-after-dist-upgrade.26097/
>>
>> Migrating from qemu 2.5 with pc-i440fx-2.4 to qemu 2.4.1 don't work.
>> qemu-system-x86_64: error while loading state for instance 0x0 of device 'fw_cfg'
> 
> While I agree that this is a bug worth fixing, note that in general
> migration from new to old versions is _not_ supported.  Usually it
> works, but not always, and sometimes it's not a bug.
> 
> Machine types are only meant to support migration from old versions to new.
> 
> Paolo
> 

I sent a patch.

Laszlo