Re: Software Plugin Interface in Xen hypervisor

[Jeremy Fitzhardinge <jeremy@goop.org>]

 On 10/27/2010 12:06 PM, Nimgaonkar, Satyajeet wrote:
> Hi Gianni,
>                   I want to actually emulate the VCPU and Memory Management Unit  and force the DOM Us to run on this new VCPU and MMU.
>                   Can you provide any pointers on how to achieve this? Thank you very much.

Do you mean a new virtual CPU architecture?  Ie, not x86?

If so, I think Xen is the wrong vehicle for your project, and you'd be
better off hacking on qemu directly.

    J

> Regards,
> Satyajeet
> ________________________________________
> From: xen-devel-bounces@lists.xensource.com [xen-devel-bounces@lists.xensource.com] on behalf of Nimgaonkar, Satyajeet [SatyajeetNimgaonkar@my.unt.edu]
> Sent: Wednesday, October 27, 2010 10:07 AM
> To: Gianni Tedesco
> Cc: Xen Devel
> Subject: RE: [Xen-devel] Software Plugin Interface in Xen hypervisor
>
> Thanks Gianni for those details, I will look into it.
> ________________________________________
> From: xen-devel-bounces@lists.xensource.com [xen-devel-bounces@lists.xensource.com] on behalf of Gianni Tedesco [gianni.tedesco@citrix.com]
> Sent: Wednesday, October 27, 2010 9:02 AM
> To: Nimgaonkar, Satyajeet
> Cc: Xen Devel
> Subject: RE: [Xen-devel] Software Plugin Interface in Xen hypervisor
>
> On Tue, 2010-10-26 at 17:24 +0100, Nimgaonkar, Satyajeet wrote:
>> Hi Gianni,
>>               I don't want to emulate devices instead I just want to create a mechanism by modifying Xen hypervisor such that I can plug in any software prototype of an architecture. So basically this mechanism will be a software plug in interface, something like how VTPM is provided in Xen.
>>               I hope this helps you to understand my question.
>>               Thanks,
> Yes I just didn't know what you meant by "architecture." Basically this
> means "emulated devices" afaict? I mean VTPM is just a hardware device
> AIUI. What I said before about qemu being the place to implement devices
> is not strictly true. Some things, such as APIC's and timers are
> implemented in the hypervisor for performance reasons.
>
> You may want to look at arch/x86/hvm/vlapic.c etc. for how this is done
> for HVM domains. For PV domains I guess we would just expose the
> relevant functionality through the hypercall interface.
>
> There isn't really a "plug in" architecture that lets you swap these
> things in and out of the hypervisor at runtime. I think most devs are
> just compiling hypervisor and etherbooting it on a separate test machine
> with serial console setup.
>
> It really depends on the very specifics of what you are doing but if you
> really want rapid dev and testing, I would consider implementing your
> devices in qemu.
>
> Gianni
>
>
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