[Fedora-xen] configuration files

Dustin Henning Dustin.Henning at prd-inc.com
Mon Mar 16 14:54:11 UTC 2009

Response below...

-----Original Message-----
From: fedora-xen-bounces at redhat.com [mailto:fedora-xen-bounces at redhat.com]
On Behalf Of Daniel P. Berrange
Sent: Monday, March 16, 2009 07:18
To: Markus Armbruster
Cc: fedora-xen at redhat.com
Subject: Re: [Fedora-xen] configuration files

On Mon, Mar 16, 2009 at 11:42:41AM +0100, Markus Armbruster wrote:
> Urs Golla <urs.golla at gmail.com> writes:
> > Hi Markus
> >
> > Thanks for your reply!
> >
> >> Because it's not XML.
> >
> > That really explains a lot ;-)
> ;)
> > I always assumed the "legacy" format from /etc/xen/mydomainconfig
> > (like in RHEL 5) is the native XEN syntax (I see this is not the
> > case.).  So, the xml format from libvirt is like a replacement for the
> > configuration in /etc/xen/mydomainconfig? But if I use virt-install
> > (e.g. in Fedora 8) to install a new machine, it does not create a file
> > /etc/xen/ and also no xml. All It does is creating the s-expression
> > file in /var/lib/.
> >
> > Is there a documentation about the relation between all this different
> > XEN / libvirt configuration files? The architecture part of the
> > documentation on libvirt.org does not answer this question.
> >
> > cheers
> Xen uses *two* native configuration file formats: S-expressions and a
> Python-like syntax.  The .sxp files you found below /var/lib/xend/ use
> the former syntax, the guest configuration in /etc/xen the latter.

To be more specific

 'xend' use /var/lib/xend for storing master config files in SXPR format.
 'xm' abuses python as a config file format in /etc/xen. XenD itself has
 no knowledge of these files, so it can't manage them. They should not
 be used in Xen >= 3.0.4 If you have existing files in /etc/xen, then you
 can load them into XenD by doing 'xm new configname', at which point
 both Xend and libvirt will be able to manage them. For Xen < 3.0.4
 libvirt has some limited support for reading /etc/xen files directly


	I should hope this won't be considered a thread hijacking, but when
you refer to using Xen >= 3.0.4, are you also referring specifically to
within Fedora (and perhaps RH & clones), or are you actually referring to
that version of Xen regardless?  Moreover, assuming you are referring
specifically to Fedora, is there any compelling reason to do this beyond the
fact that virt-install and Xen both support it and can then play nice?  I
ask because I still use /etc/xen and xm python-like config files, primarily
because I can then quickly and easily edit those config files, but also
because I use the functionality in /etc/xen/auto (and related config files)
for startup and shutdown (which incidentally does appear somewhat broken
specifically in F8 [EOL, I know, but it has appeared broken since some
number of updates ago, and that might be the compelling reason]).

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