RE: [Xen-devel] Re: Xen is a feature

From: Nakajima, Jun
Date: Fri May 29 2009 - 19:09:37 EST

On 5/29/2009 11:34:40 AM, Andi Kleen wrote:
> George Dunlap <george.dunlap@xxxxxxxxxxxxx> writes:
> cc list from hell trimmed.
> > allowing Linux to run as dom0 *is* improving Linux. The lack of
> > dom0 support is at this moment making life more difficult for a huge
> > number of Linux users who use Xen, including Mozilla, Debian, and Amazon.
> > Adding dom0 support would make Linux even more useful to a wide
> > variety of people not using Xen at the moment.
> Perhaps one way to address this problem would be to make the Dom0
> interface less intrusive for the host OS?
> Maybe impression last time I looked was that there was huge potential
> of improvement in this area. For example the PAT issue recently
> discussed was completely unnecessary. Or if you added a "VT/SVM only"
> Dom0 mode I'm sure the interface would be significantly cleaner too.
> If you can come up with a slim clean interface the chances for actual
> integration would be likely much higher.

I think we still need some (or all?) of additional dom0 PV ops even for HVM (Hardware-based VM) dom0. Hardware-based virtualization can significantly clean up the CPU-related PV ops (including some for local APIC), but they have nothing to do with dom0.

Some hooks in the host could be removed by reusing the HVM-specific code with modifications to the virtualization logic, but I think people need to tell which specific ones are intrusive, to be fair.

Jun Nakajima | Intel Open Source Technology Center
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