Re: [Qemu-devel] [PATCH RFC 0/7] Netfilter: Add each netdev a default filter

[Daniel P. Berrange]

On Fri, Jan 22, 2016 at 06:35:48PM +0800, Hailiang Zhang wrote:
> On 2016/1/22 18:07, Daniel P. Berrange wrote:
> >On Fri, Jan 22, 2016 at 04:36:44PM +0800, zhanghailiang wrote:
> >>This series is a prerequisite for COLO, here we add each netdev
> >>a default buffer filter, it is disabled by default, and has
> >>no side effect for delivering packets in net layer.
> >
> >Why can't whatever is launching QEMU just setup filters explicitly
> >if they want to use COLO ? I'm not seeing an obvious compelling
> >reason to add this by default and then add extra code to deal
> >with special casing its behaviour.
> >
> 
> The main reason is, we hope to support hot add network during VM's COLO
> lifetime in the future. (I'm not quite sure if this usage case is really 
> exist,
> but we don't want the VM in COLO state has too many limitations.)
> 
> Maybe add an option that users can control if they want to use COLO or not is 
> more
> acceptable ? With this option, we can decide whether to add the default 
> filter or not.
> Or, we could dynamically add filter while users ask to go into COLO state for 
> VM.
> (We have discussed this before in community, and Jason suggested me to add 
> default
> filter for each netdev to support hot-add network during COLO state).
> 
> What's your suggestion ?

Why can't the app hot-adding the network interface also configure a
filter at that time if they're using COLO ?

Regards,
Daniel
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