Re: [Qemu-devel] [PATCH v4 1/1] Introduce "xen-load-devices-state"

[Eric Blake <eblake@redhat.com>]

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On 05/30/2016 09:17 AM, Stefano Stabellini wrote:
> On Fri, 27 May 2016, Anthony PERARD wrote:
>> On Mon, Apr 11, 2016 at 11:56:02AM +0800, Changlong Xie wrote:
>>> From: Wen Congyang <wency@cn.fujitsu.com>
>>>
>>> Introduce a "xen-load-devices-state" QAPI command that can be used to
>>> load the state of all devices, but not the RAM or the block devices of
>>> the VM.
>>>
>>> We only have hmp commands savevm/loadvm, and qmp commands
>>> xen-save-devices-state.
>>>
>>> We use this new command for COLO:
>>> 1. suspend both primary vm and secondary vm
>>> 2. sync the state
>>> 3. resume both primary vm and secondary vm
>>>
>>> In such case, we need to update all devices' state in any time.
>>>
>>> Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
>>> Signed-off-by: Changlong Xie <xiecl.fnst@cn.fujitsu.com>
>>
>> This patch looks good to me.
>>
>> Reviewed-by: Anthony PERARD <anthony.perard@citrix.com>
> 
> It would be nicer (and less problematic) to load the state from a file
> descriptor, but given that we still saving the state to file, it would
> be unfair to ask to use file descriptors here.

If you use qemu_open(), then you can pass the magic "/dev/fdset/1"
notation to use a file descriptor previously added to an fdset.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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