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Date: Wed, 24 Mar 2010 06:53:02 +0200
From: Avi Kivity <avi@redhat.com>
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Subject: Re: [Qemu-devel] Supporting hypervisor specific APIs in libvirt
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To: Anthony Liguori <anthony@codemonkey.ws>
Cc: "libvir-list@redhat.com" <libvir-list@redhat.com>, qemu-devel <qemu-devel@nongnu.org>

On 03/23/2010 09:31 PM, Anthony Liguori wrote:
>
>>
>> One problem is that this is libvirt version specific.  For example, 
>> libvirt x doesn't support spice so we control that thorough qmp.  But 
>> libvirt x+1 does support spice and now it gets confused about all the 
>> spice messages.
>
> That's only a problem if we only support a single QMP session.  This 
> is exactly why we need to support multiple QMP sessions (and do).

It's unrelated to the number of sessions.  libvirt expects state that it 
manages in qemu not to change randomly.  Users know that, so they will 
only manage non-libvirt state in their private session.  But a new 
version of libvirt may expand its scope and start managing this area, 
leading to conflicts.

-- 
Do not meddle in the internals of kernels, for they are subtle and quick to panic.