Re: [Qemu-devel] [PATCH] net: Add persistent flag to -net tap option

["Daniel P. Berrange" <berrange@redhat.com>]

On Fri, Dec 19, 2014 at 01:13:50PM +0000, Stefan Hajnoczi wrote:
> On Mon, Dec 15, 2014 at 02:05:23PM +0200, Roy Vardi wrote:
> > From: Roy Vardi <royv@ezchip.com>
> > 
> >     Add 'persistent' boolean flag to -net tap option.
> >     When set to off - tap interface will be released on shutdown
> >     When set to on\not specified - tap interface will remain
> > 
> >     Running with -net tap,persistent=off will force the tap interface
> >     down when qemu goes down, thus ensuring that there're no zombie tap
> >     interfaces left
> > 
> >     This is achieved using another ioctl
> > 
> >     Note: This commit includes the above support only for linux systems
> 
> I don't understand the point of this patch.  The following doesn't
> persist the tun interface:
> 
> qemu-system-i386 -net tap,script=myscript.sh,downscript=no -net nic
> 
> You are changing the default to persist the interface, won't this cause
> problems for existing users who don't expect persistent interfaces?

Yea, changing the default to persist interfaces is going to cause existing
apps using this syntax to leak these tap devices on QEMU shutdown.

Regards,
Daniel
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