RE: [Xen-devel] Re: is the xen toolstack backwards compatible ?

[Dan Magenheimer <dan.magenheimer@xxxxxxxxxx>]

Excellent!

I think it would be a great service for many developers if
you could clearly document all the steps on a Xen wiki
page.  Maybe start with:

"Assume you have a distro-supplied Xen with version < 4.0
installed on your machine and you wish to also build/install
either Xen 4.0 or xen-unstable PARALLEL to the distro
installation so that you can easily switch between the
distro version and the newer version.  Follow these steps..."

Thanks,
Dan

> -----Original Message-----
> From: Christoph Egger [mailto:Christoph.Egger@xxxxxxx]
> Sent: Wednesday, December 09, 2009 9:57 AM
> To: Dan Magenheimer
> Cc: Sander Eikelenboom; xen-devel@xxxxxxxxxxxxxxxxxxx; Keir Fraser
> Subject: Re: [Xen-devel] Re: is the xen toolstack backwards 
> compatible ?
> 
> 
> On Wednesday 09 December 2009 16:14:57 Dan Magenheimer wrote:
> > Hi Christophe --
> >
> > What is the earliest version of the tools for which this will work?
> 
> Xen-unstable.
> 
> > For example, can it be used to switch back and forth between
> > a 3.4.0-based Xen/toolstack and a xen-unstable-based Xen/toolstack
> > on the same machine?  If so, I would appreciate more information!
> 
> Yes, that is possible. Install Xen-unstable in a different directory
> than you are "forced" to install Xen 3.4 to.
> 
> You can switch forth and back between Xen-unstable and Xen 3.4
> by setting the environment variables as described.
> 
> Whenever you switch forth and back you have to consider to adapt
> the guest config files.
> Xen 3.4 requires the full path to hvmloader and to qemu-dm while
> the path is optional in Xen-unstable.
> 
> Be sure that the correct hvmloader and qemu-dm is used
> when you switch.
> 
> The same way you can also switch back and forth between
> Xen 3.3 and Xen-unstable.
> 
> Christoph
> 
> 
> 
> > Thanks,
> > Dan
> >
> > > -----Original Message-----
> > > From: Christoph Egger [mailto:Christoph.Egger@xxxxxxx]
> > > Sent: Wednesday, December 09, 2009 4:43 AM
> > > To: Sander Eikelenboom
> > > Cc: xen-devel@xxxxxxxxxxxxxxxxxxx; Keir Fraser
> > > Subject: [Xen-devel] Re: is the xen toolstack backwards 
> compatible ?
> > >
> > > On Wednesday 09 December 2009 12:25:40 Sander Eikelenboom wrote:
> > > > Hmmm so i could make  the paths:
> > > >
> > > > export LD_LIBRARY_PATH="/usr/local/lib/<xen_hypervisor_version>"
> > > > export
> > >
> > > PYTHONPATH="/usr/local/lib/<xen_hypervisor_version>/python2.5/
> > > site-packages
> > >
> > > >"
> > > >
> > > > And let a startup script make symlinks to the right 
> tools for the
> > > > hypervisor version that is booted (and perhaps config
> > >
> > > files), then the only
> > >
> > > > place to worry about hypervisor and kernel version is grub.
> > >
> > > Quite.
> > >
> > > In your case I would compile the tools with
> > > PREFIX="/usr/<xen_hypervisor_version>"
> > > and set
> > >
> > > export LD_LIBRARY_PATH="/usr/<xen_hypervisor_version>/lib"
> > > export
> > > PYTHONPATH="/usr/<xen_hypervisor_version>/python2.5/site-packages"
> > > export PATH="$PATH:/usr/<xen_hypervisor_version>/sbin"
> > >
> > > Then a simple 'xend start' on the command line (or via
> > > startup script) is
> > > enough.
> > >
> > > > But i think it's perhaps not worth the trouble and a bit
> > >
> > > ugly to make that
> > >
> > > > general, so just drop the idea :-)
> > >
> > > I do that manually and that works great to switch between
> > > different versions
> > > for my development/testing effort.
> > >
> > > Christoph
> > >
> > > > --
> > > >
> > > > Sander
> > > >
> > > > Wednesday, December 9, 2009, 11:06:58 AM, you wrote:
> > > > > On Wednesday 09 December 2009 08:22:14 Keir Fraser wrote:
> > > > >> On 09/12/2009 00:23, "Sander Eikelenboom"
> > >
> > > <linux@xxxxxxxxxxxxxx> wrote:
> > > > >> > So if it was no coincidence but desirable, at the
> > >
> > > moment xend and
> > >
> > > > >> > xentop from unstable don't seem to work on 3.4.2
> > >
> > > hypervisor anymore.
> > >
> > > > >> There's no compatibility guarantee across different
> > >
> > > major Xen releases.
> > >
> > > > >> But Christoph Egger did a lot of work to allow multiple
> > >
> > > toolstacks to be
> > >
> > > > >> installed side by side. I think you should just need 
> to specify a
> > > > >> PREFIX=/path/to value when building the tools. Is that
> > >
> > > right, Christoph?
> > >
> > > > > Yes, this is right.
> > > > > *Before* you start xend, you need to set two 
> environment variables
> > > > > LD_LIBRARY_PATH and PYTHONPATH.
> > > > >
> > > > > Here is an example for PREFIX="/usr/local" and compiled
> > >
> > > with python 2.5:
> > > > > export LD_LIBRARY_PATH="/usr/local/lib"
> > > > > export PYTHONPATH="/usr/local/lib/python2.5/site-packages"
> > > > >
> > > > > If these are not set correct, python tells you it can't
> > >
> > > find its modules
> > >
> > > > > or the dynamic linker tells you it can't find the shared
> > >
> > > libs built from
> > >
> > > > > tools/libxc.
> > > > >
> > > > > You should use the same python version you compiled with.
> > > > > If you are on a machine where 'python' does not exist as
> > >
> > > a symbolic link
> > >
> > > > > to the installed python version (like me on NetBSD) you
> > >
> > > need the attached
> > >
> > > > > patch or all python programs installed with 
> "INSTALL_PYTHON_PROG"
> > > > > end up with '#!' in the first line instead of
> > >
> > > '#!/path/to/python2.5'
> > >
> > > > > which is stupid.
> > > > >
> > > > > I already submitted attached patch earlier but Ian
> > >
> > > Jackson objected it
> > >
> > > > > because he wants a way to have tools working with a
> > >
> > > different python
> > >
> > > > > version than it has been compiled with. This sounds
> > >
> > > obscure to me when
> > >
> > > > > looking at the path python modules get installed to.
> > > > >
> > > > > Keir: Please take attached patch. This is better than 
> the current
> > > > > situation regardless Ian likes it or not. In the latter
> > >
> > > case taking the
> > >
> > > > > patch should motivate him to come up with a patch finally. :)
> > > > >
> > > > > Again:
> > > > > Signed-off-by: Christoph Egger <Christoph.Egger@xxxxxxx>
> > >
> > > --
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> > >
> > >
> > > _______________________________________________
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> 
> 
> 
> -- 
> ---to satisfy European Law for business letters:
> Advanced Micro Devices GmbH
> Karl-Hammerschmidt-Str. 34, 85609 Dornach b. Muenchen
> Geschaeftsfuehrer: Andrew Bowd, Thomas M. McCoy, Giuliano Meroni
> Sitz: Dornach, Gemeinde Aschheim, Landkreis Muenchen
> Registergericht Muenchen, HRB Nr. 43632
> 
> 
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