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RE: [Xen-devel] New release candidate for Xen 4.0.0 (RC9)

> From: Ian Pratt [mailto:Ian.Pratt@xxxxxxxxxxxxx]
> To: Joanna Rutkowska; Keir Fraser
> Subject: RE: [Xen-devel] New release candidate for Xen 4.0.0 (RC9)
> > http://xenbits.xensource.com/
> That page seriously needs fixing to correctly reflect the active trees.
> > one can see linux-2.6.18-xen.hg repo as a sub-repo of the just-
> created
> > xen-4.0-testing.hg... I was under impression that 4.0 would be using
> > pvops0 kernel *only* and that you would not support 2.6.18 anymore
> for
> > this hypervisor...
> I don't think it makes sense for anyone to really be using 2.6.18
> anymore.

Sorry, I have to disagree.  The only real issue with 2.6.18 is
old drivers.  If your machine works fine with 2.6.18 dom0, it
is still very likely the most stable and fully-functional dom0
bits and has been tested with many previous releases of Xen
and was the default for pre-4.0 until a few months ago.
One need only look at the changelog to see it is still
actively used: http://xenbits.xensource.com/linux-2.6.18-xen.hg 
I have used this tree for all of my 4.0 development and testing.

You will likely have problems with it on newer hardware...
though I have been developing/testing fine on a Nehalem box.
> The 2.6.27 tree is probably the most widely tested right now, and is
> shipping in commercial xen distros, and xen.org's Xen Cloud Platform
> and XCI.

I don't want to get into a numbers argument, but all Oracle VM
shipments are using a 2.6.18-based dom0.  And I'd venture to
guess that, since most enterprise shops rarely move immediately to
the leading edge release, the vast majority of commercial Xen users
are using a 2.6.18-based dom0.

> pvops is certainly where the development effort is currently focussed,
> and hopefully what the commercial distros will all be using later this
> year[*].

Yes, agreed.  This is definitely the direction.  But I don't
think it's time to throw away linux-2.6.18-xen.hg quite yet
(the suggestion of which is what triggered my allergic reaction
here :-).
> > Can you shed some light on this issue -- why is this kernel repo
> there,
> > and what kernel will *really* be the official and stable option for
> Xen 4?
> > What will be part of the next week release?

Keir already answered this tersely, but let me explain further
(and others can correct me if I am wrong).  There IS NO official
dom0 for Xen 4.0 from xen.org.  Xen 4.0 is a hypervisor not
a virtualization distro.  Similarly, Linux 2.6.33 is a kernel release,
not an OS distro.  Distros of both are free to choose whatever other
components work best for their customers.

So IMHO the http://xenbits.xensource.com/linux-2.6.18-xen.hg tree
is still maintained because it is still useful for a significant
number of developers.

P.S. I *do* plan to switch to pvops... but I've been saying that
for over a year now ;-)

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