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Re: [Qemu-devel] [PATCHv2 08/11] block-migration: efficiently encode zer
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [PATCHv2 08/11] block-migration: efficiently encode zero blocks |
Date: |
Tue, 02 Jul 2013 12:51:14 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130514 Thunderbird/17.0.6 |
Il 02/07/2013 09:40, Stefan Hajnoczi ha scritto:
> On Mon, Jul 01, 2013 at 05:55:15PM +0200, Peter Lieven wrote:
>>
>> Am 01.07.2013 um 16:13 schrieb Stefan Hajnoczi <address@hidden>:
>>
>>> On Thu, Jun 27, 2013 at 03:11:32PM +0200, Peter Lieven wrote:
>>>
>>> This patch breaks cross-version blog migration. We need to control
>>> whether or not to use the new BLK_MIG_FLAG_ZERO_BLOCK flag.
>>
>> you are right the upgrade way works, but downgrade not. what is the
>> proposed way to fix this?
>
> The safest way is to add a block migration flag that toggles the zero
> block. By default it would be off.
>
> Maybe you would also add a MigrationCapability in qapi-schema.json to
> indicated that zero blocks are supported in block migration. That would
> allow management tools to ask QEMU on both sides if they support zero
> blocks.
>
> Use migrate-set-capabilities to enable the zero block feature.
Yes, a capability makes sense.
Paolo