Re: [Xen-devel] Re: [Qemu-devel] vnc port selection

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

On Thu, Aug 21, 2008 at 09:30:21PM +0300, Avi Kivity wrote:
> Gerd Hoffmann wrote:
> >  Hi folks,
> >
> >Xen's qemu-dm version has a '-vncunused' command line switch which asks
> >the internal vnc server to pick any unused tcp port to listen on.  The
> >actual port is communicated to the outside world via xenstore.
> >
> >I'm looking for a reasonable way to implement that functionality in
> >upstream qemu.  First, I think it shouldn't be a separate command line
> >switch but an option for the existion -vnc switch.  Second, we need a
> >way to communicate the port picked which isn't xen-specific.  Obvious
> >choice is a monitor info subcommand.
> >
> >Comments?  Other suggestions?
> >
> >  
> 
> Presumably -vncunused is passed by the management application, which 
> knows about all domains.  Can't it figure out an unused port and pass it on?
>

Yes & no. Yes, we do this in libvirt, but it open a race condition
unless you pass the actual file descriptor to QEMU. In addition when
we add IPv6 support to QEMU, you will actally have multiple sockets
you need to listen on. It will make it far easier if we just do the
right thing in QEMU, based on a command line flag. 

Daniel
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