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[Xen-users] Re: Xen is a feature

To: Steven Rostedt <rostedt@xxxxxxxxxxx>
Subject: [Xen-users] Re: Xen is a feature
From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Date: Wed, 3 Jun 2009 01:41:43 +0200 (CEST)
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On Tue, 2 Jun 2009, Steven Rostedt wrote:
> If we were to break an interface with Dom0 for Xen then we would have a bunch
> of people crying foul about us breaking a defined API. One of Thomas's 
> complaints
> (and a valid one) is that once Linux supports an external API it must always
> keep it compatible. This will hamper new development in Linux if the APIs are
> scattered throughout the kernel without much thought.
> Now here's a crazy solution. Merge the Xen hypervisor into Linux ;-)

Not that crazy as you might think.
> Give full ownership of Xen to the Linux community. One of your people could be
> a maintainer. This way the API between Dom0 and the hypervisor would be an 
> internal

s/API/ABI/ :) 

> one. If you needed to upgrade Dom0, you also must upgrade the hypervisor, but 
> that
> would be fine since the hypervisor would also be in the Kernel proper.
> This may not solve all the issues that the x86 maintainers have with the Dom0
> patches, but it may help solve the API one.

In fact it would resolve the ABI problem once and forever as we could
fix hypervisor / dom0 in sync. hypervisor and dom0 need to run in
lock-step anyway if you want to make useful progress aside of
maintaining versioned interfaces which are known to bloat rapidly.

It's not a big deal to set a flag day which says: update hypervisor
and (dom0) kernel in one go.



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