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Re: [Xen-devel] libxl - API call to return sxpr of a domain?

To: "rshriram@xxxxxxxxx" <rshriram@xxxxxxxxx>
Subject: Re: [Xen-devel] libxl - API call to return sxpr of a domain?
From: Ian Campbell <Ian.Campbell@xxxxxxxxxx>
Date: Tue, 7 Jun 2011 10:02:59 +0100
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On Tue, 2011-06-07 at 04:30 +0100, Shriram Rajagopalan wrote:
> I am looking into adding Remus support for libxl. The easiest way is
> to obtain the domain's sxpr, so that the rest of Remus python code
> stays as is.
> Is there an api call in libxl to return a domain's sxpr ? a grep on
> the libxl code
> base returned nothing. Or am I missing something pretty obvious?

xl has some code to do this but libxl doesn't. An sxpr representation of
a domain is rather a xend specific concept which is the only reason xl
has it.

There are some plans to allow libxl to generate json for any of the IDL
defined datastructures, mostly as a convenient pretty-printer but being
machine parsable is a handy side-effect. Currently this would just be
for individual datastructures though.

Where/how does remus use sxp? tools/python/xen/remus/vm.py:domtosxpr()
seems to consume a xend datastructure and make a Remus sxp out of it --
can an xl equivalent not be written using the python bindings? (NB
bindings may be incomplete, we can fix up as you discover stuff). Are
all usages of sxp in Remus of that particular sxp format or are there

Are sxp's baked into the Remus wire-protocol? Personally I think moving
away from using SXPs internally towards using actual data structures
would be a good idea...

BTW, is tools/python/xen/remus part of xend or part of Remus? Or does it
straddle the boundary?


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