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RE: [Xen-devel] [PATCH]: xl: use libuuid to generate random UUID's

On Tue, 2010-08-10 at 16:23 +0100, Ian Jackson wrote:
> Gianni Tedesco (3P) writes ("RE: [Xen-devel] [PATCH]: xl: use libuuid to 
> generate random UUID's"):
> > On Mon, 2010-08-09 at 11:51 +0100, Ian Jackson wrote:
> > > VM uuids are not stable in xend nor xl.  Perhaps xl should hash the VM
> > > name, which is stable and supposedly unique.
> > 
> > But they can be made to be stable and I suppose this is the point here.
> No, I don't think VM uuids can be made stable in xl.  If for no other
> reason than that localhost migration would be impossible.

Oh right, good point.

> I think the only way to have stable MAC addresses is to derive them
> from the VM name, or for the user to explicitly write a MAC address in
> the config file.

VM's can have the same name, so either ought to be an "domain image" (or
something) UUID or just manually specify the mac.

> Users who do the latter will find things continue to work no matter
> how we change the default scheme, and the default is already somewhat
> broken, so perhaps we should indeed consider changing it.

I think in the absence of explicit instruction on what to set the MAC
to, picking it randomly would is a sensible approach. Whether it ought
to be in the local or global address namespace seems like the only
decision to make in this case.

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