Re: [Xen-devel] Guest knowledge of own domid [was: docs: initial documentation for xenstore paths]

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Thu, 2012-08-16 at 15:33 +0100, Daniel De Graaf wrote:

> >> and if two domains are attempting to
> >>> set up communication such as V4V or vchan, they need to be able to tell
> >>> their peer what domain ID to use.
> > 
> > That's trickier.
> > 
> > I suppose they could rendezvous via /vm/$UUID? Although there has been
> > talk of removing that path in the future.
> 
> The /vm/$UUID path isn't currently useful for this, since it doesn't maintain
> domain IDs (just names) and doesn't contain writable sub-keys for a domain
> to use. I also don't think such a sub-key should be added; it makes more
> sense to keep all of a domain's modifiable keys under its home path.
> 
> Perhaps this could be changed to another identifier-to-domid mapping, like
> the proposed addition of a location to map name to domid? 
> 
> The toolstack would maintain something like:
>   /local/by-name/$name == domid
>   /local/by-uuid/$uuid == domid

This second one is a bit like the existing /vm/$uuid/domid.

I think I would go with:

  /local/by-name/$name == /local/domain/$domid
  /local/by-uuid/$uuid == /local/domain/$domid

though, So that you can just read it and use it without interpreting it.

>   /local/domain/$domid/name - same as existing
>   /local/domain/$domid/uuid - ? maybe unneeded, as it's available from Xen.

Is it available for other domains via xen, or just yourself?

Ian.


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