[libvirt] Re: [Qemu-devel] [PATCH 1/6] Allow multiple monitor devices (v2)
Avi Kivity
avi at redhat.com
Tue Apr 14 09:15:23 UTC 2009
Daniel P. Berrange wrote:
> Yes indeed its a little crazy :-) As anthony mentioned if libvirt were
> able to be notified of changes a user makes in the monitor, there's no
> reason we could not allow end users to access the monitor of a VM
> libvirt is managing. We just need to make sure libvirt doesn't miss
> changes like attaching or detaching block devices, etc, because that'll
> cause crash/data loss later when libvirt migrates or does save/restore,
> etc because it'll launch QEMU with wrong args
>
You still have an inherent race here.
user: plug in disk
libvirt: start migration, still without disk
qemu: libvirt, a disk has been plugged in.
>> I don't see how adding those low-level monitory things to libvirt is
>> an improvement - debugging and scripted keystrokes are not the sort of
>> functionality libvirt is for - or is it?
>>
>
> I think it could probably be argued that sending fake keystrokes could
> be within scope. Random ad-hoc debugging probably out of scope.
>
That means that to debug a problem in the field you have to locate a
guest's host, and follow it around as it migrates (or disable migration).
--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.
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