Re: [Xen-devel] [FW: FYI: The plan for Xen kernels in Fedora 9]

[Mark Williamson <mark.williamson@xxxxxxxxxxxx>]

> In the spirit of improving communication of Fedora Xen plans to the world,
> below is a mail I recently circulated in the Fedora community about the
> direction for Xen-ified kernels from Fedora 9 and onwards.
>
> The short story, is that we intend to ship hypervisor & userspace based on
> Xen 3.2.0 tree, and a kernel based on latest LKML pv_ops tree and patches
> ontop of that to support Dom0 and x86_64. With some short term pain and
> instability, we hope to get significant long term benefits for support of
> Xen Linux kernels.

Sounds like the best possible and longterm-sustainable plan and good for 
everybody involved.

Question: do the dom0-compatibility patches have any chance of getting into 
kernel.org?  Or would they continue to live as a patchset?

Cheers,
Mark

> The long story is the mail below..
>
> We have a number of kernel guys working on this project, and Stephen will
> shortly followup with details of his current patch queue, for benefit of
> anyone else who wishes to track this / get involved.
>
> Regards,
> Dan.
>
> ----- Forwarded message from "Daniel P. Berrange" <berrange@xxxxxxxxxx>
> -----
>
> > Date: Fri, 30 Nov 2007 18:59:09 +0000
> > From: "Daniel P. Berrange" <berrange@xxxxxxxxxx>
> > To: fedora-xen@xxxxxxxxxx
> > Subject: FYI: The plan for Xen kernels in Fedora 9
> >
> > This is a friendly alert of the major plans we have for Xen kernels in
> > Fedora 9 timeframe...
> >
> > Since we first added Xen in Fedora Core 5, our kernels have been based on
> > a forward-port of XenSource's upstream Xen kernels, to new LKML. For a
> > long time we ported their 2.6.16 tree to 2.6.18. Now we do ports of their
> > 2.6.18 tree to 2.6.21/22/23, etc.  At the same time, upstream Linux
> > gained Xen support for i386 DomU, and shortly x86_64  DomU, and is
> > generally getting ever more virtualization capabilities.
> >
> > As everyone knows, we have tended to lag behind Fedora's state-of-the-art
> > bare metal kernels by several releases due to the effort required to port
> > Xen to newer LKML releases. Despite our best efforts, this lag has been
> > getting worse, not better.
> >
> > We have taken the decision, that this situation is unacceptable for
> > Fedora 9. We simply cannot spend more time forward porting Xen kernels.
> > Either Xen has to be dropped entirely, or we need a different strategy
> > for dealing with the kernels. Since people seeem to use Xen, we have
> > decided not to drop it :-)
> >
> > So the plan is to re-focus 100% of all Xen kernel efforts onto
> > paravirt_ops. LKML already has i386 pv_ops + Xen DomU. We intend to build
> > on this to add:
> >
> >   - x64_64 pv_ops
> >   - x86_64 Xen DomU on pv_ops
> >   - i386 & x86_64  Xen Dom0  on pv_ops
> >   - memory balloon
> >   - paravirt framebuffer
> >   - save/restore
> >
> > All of this based on same LKML release as Fedora bare metal. If all goes
> > to plan it may even be in the base kernel RPM, instead of kernel-xen, but
> > thats a minor concern compared to the actual coding.
> >
> > Getting all this done for Fedora 9 is seriously ambitious, but it is the
> > only long term sustainable option, other than dropping Xen entirely.
> >
> > What this means though, is that Fedora 9 Xen will certainly be going
> > through periods of instability and will certainly be even buggier than
> > normal. F9 may well end up lacking features compared to Xen in Fedora 8 &
> > earlier (eg no PCI device passthrough, or CPU hotplug). On the plus side
> > though we will be 100% back in sync with bare metal kernel versions &
> > hopefully even have a lot of this stuff merged in LKML to make ongoing
> > maintainence sustainable. Short term pain; Long term gain!
> >
> > I have not got any ETA on when any of these kernel changes will appear in
> > rawhide - some time before the F9 feature freeze date is best
> > guesstimate. We will alert people when the time comes. There is a F9
> > feature page with some amount of info about the plan...
> >
> >    http://fedoraproject.org/wiki/Features/XenPvops
> >
> > In terms of Fedora 6/7/8 maintainence... The kernel-xen in these existing
> > releases already lags behind the bare metal kernel version by 2-3
> > releases. We do not intend to continue trying to rebase the kernel-xen in
> > existing Fedora releases. It will be essentially important bug-fix mode
> > only. This is neccessary to enable maximum resources to be focused on the
> > critical Fedora 9 Xen work.
> >
> > Regards,
> > Dan ...on behalf of some very busy Fedora Xen kernel developers :-)
> > --
> >
> > |=- Red Hat, Engineering, Emerging Technologies, Boston.  +1 978 392 2496
> > | -=| =-           Perl modules: http://search.cpan.org/~danberr/        
> > |      -=| =-               Projects: http://freshmeat.net/~danielpb/    
> > |           -=| =-  GnuPG: 7D3B9505   F3C9 553F A1DA 4AC2 5648 23C1 B3DF
> > | F742 7D3B 9505  -=|
>
> ----- End forwarded message -----



-- 
Dave: Just a question. What use is a unicyle with no seat?  And no pedals!
Mark: To answer a question with a question: What use is a skateboard?
Dave: Skateboards have wheels.
Mark: My wheel has a wheel!

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