From mboxrd@z Thu Jan  1 00:00:00 1970
From: Juergen Gross <jgross@suse.com>
Subject: Re: PVHVM drivers in upstream linux kernel
Date: Tue, 02 Dec 2014 14:00:50 +0100
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To: David Vrabel <david.vrabel@citrix.com>, Ian Campbell <Ian.Campbell@citrix.com>
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On 12/02/2014 12:59 PM, David Vrabel wrote:
> On 02/12/14 11:33, Juergen Gross wrote:
>>
>> I think we have customers wanting to run a default kernel as domU. So it
>> isn't always the distro refusing paravirt, it might be the user...
>
> I don't think this is a sensible use case but I'm not adverse to
> improving the set of Xen config options.
>
>> To sort things out I'd suggest to:
>> - make XEN independent from PARAVIRT
>> - let XEN_DOM0 select XEN_BACKEND, PARAVIRT, XEN
>> - let XEN_BACKEND select PARAVIRT, XEN (I'd like to be able to build
>>    a driver domain without XEN_DOM0)
>> - introduce XEN_FRONTEND, let it select XEN
>> - let frontend drivers and drivers needed by those depend on
>>    XEN_FRONTEND
>> - let XEN_PVHVM select XEN_FRONTEND
>
> Rather than looking at the current set of configuration options, can you
> look at what user-visible functionality or use cases need to be covered
> by a (potentially new) set of configuration options?

I'd see:
- XEN_PV (selects PARAVIRT, XEN_FRONTEND): be able to run as pv-domain
   (x86 only)
- XEN_PVHVM (selects XEN_FRONTEND): be able to run as hvm-domain with
   pv-drivers
- XEN_BACKEND (selects PARAVIRT if x86): be able to run as driver domain
   (dom0 or other)
- XEN_DOM0 (selects PARAVIRT if x86, XEN_BACKEND): be able to run as
   dom0
- XEN_FRONTEND: be able to run as domU with pv-drivers


Juergen