Re: [Xen-devel] Notification on a domU creation and a XenBus watch question

[Mark Williamson <mark.williamson@xxxxxxxxxxxx>]

> I am writing a module for dom0 which needs to be notified when a domain is
> created/destroyed. Is that possible?

Do you mean a kernel module?

But yes, if you create the appropriate watches using the XenBus API I think 
you should be able to get notifications.  Or in userspace you can use C or 
Python to register Xenbus watches.

> And is it possible to add a watch on 
> all /local/domain/<id>/path/key without specifying the domain ID? I mean
> the watch should be on all /path/key of the currently executing domains.
> Does XenBus support this or will I have to individually add a watch on all
> /local/domain/<id>/path/keys?

As far as I know you'd need to register a watch on each path separately at the 
moment...

In the future, I was thinking it might be nice to have a "/local/services/" 
directory which everyone could watch and which domain could post 
notifications in.  e.g. if everyone is interested in the "foo" service, they 
could watch /local/services/foo.  If domain 5 wants to advertise this service 
they'd post into "/local/services/foo/5/" to tell everyone about it.  I've 
never got round to implementing it but I'm curious whether this would suit 
the application you have in mind?

Cheers,
Mark

-- 
Dave: Just a question. What use is a unicyle with no seat?  And no pedals!
Mark: To answer a question with a question: What use is a skateboard?
Dave: Skateboards have wheels.
Mark: My wheel has a wheel!

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