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I don't believe zero is a valid evtchn#, is > >> it? > > > > gfn 0 might be valid, but I'm also pretty sure evtchn 0 is not valid. > > GFN 0 very much is valid. > > evtchn 0 OTOH is explicitly not valid.  From evtchn_init(): > >     evtchn_from_port(d, 0)->state = ECS_RESERVED; > > > However, the fields being 0 doesn't mean not available.  That's the > signal to saying "not connected yet", because that's what dom0 gets > before xenconsoled starts up. Someone asked me the same a while back, and IIRC we don't state anywhere in the public headers that event channel 0 is reserved, however that has always? been part of the implementation. If we intend this to be reliable, we should add a define to the public headers in order to signal that 0 will always be reserved. Roger.