Re: vifs not working?

[der Mouse <mouse%Rodents.Montreal.QC.CA@localhost>]

> I guess my thought is, without an ethernet device nor a bridge, how
> is a vif to communicate?  What exactly are you pinging?

The dom0 and the domU communicate with one another.

dom0# ifconfig vif3.0 10.1.0.1/24
domU# ifconfig xennet0 10.1.0.2/24
dom0# ping 10.1.0.2
...works...
domU# ping 10.1.0.1
...works...

The documentation says that the xennet interface and the vif interface
are effectively like a crossover cable between two Ethernet ports.
Except for the issue that they don't stay around because the "hotplug
scripts", whatever they are, aren't working, that's exactly how they
seem to be behaving.

>> I don't see what PCI access has to do with it; nothing says there's
>> a PCI bus anywhere in sight.
> No ... but if you were to opt out of a bridge, then you'd usually
> choose a physical interface.  Unless there is some other way to
> emulate the physical layer that I'm unaware of (quite possibly).

I don't see why you'd need to.  The xennet interface in the domU seems
to communicate with its corresponding vif interface in the dom0 just
fine.  Whether the vif interface happens to be a member of a bridge is,
as far as I can see, entirely orthogonal to this - or, at least, it
should be; I can't see why a vif being a member of a bridge would
matter to anything.

The whole auto-bridging thing seems to be built around the assumption
that you want the domUs and the dom0 to, effectively, share a physical
interface.  If you do, this is fine, but if you don't - if you'd rather
have the domUs form one or more small private networks with the dom0 as
a router between them and the real network, or if you don't want the
domUs to communicate with anything beyond the dom0 - I can't see why
that should be a problem.

> The bridge is merely required to emulate the use of a physical
> interface.

I don't see why.  The xennet/vif pair seems to emulate two physical
interfaces connected to one another just fine.  If I happen to want to
bridge a vif with a real interface, great, but I can't see any reason I
should have to if I'd rather not.

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