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

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

This sounds like an excellent plan to me!

 -- Keir

On 10/12/07 15:20, "Daniel P. Berrange" <berrange@xxxxxxxxxx> wrote:

> 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.
> 
> 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 -----



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