[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Xen-devel] Re: [RFC, PATCH 5/24] i386 Vmi code patching

xen-devel-bounces@xxxxxxxxxxxxxxxxxxx wrote on 03/23/2006 06:45:54 PM:

> Keir Fraser wrote:
> > We could extend the concept of the interface shim we already have -- a
> > set of OS-specific high performance shims, plus a fallback OS-agnostic
> > shim.
> Currently the lack of a shim is the key difference between the VMI and
> Xen approaches. Forgive me for summarizing, but I'm not sure it's been
> made clear. The VMI is the interface between the OS and a shim layer--it
> is not a hypervisor interface. The kernel makes VMI calls to the shim
> and the shim makes hypercalls, if needed, to the hypervisor.
>      VMI                   VMI native            Xen/Xen native
>       OS                      OS                     OS
> -------------- VMI      -------------- VMI
>    Shim (ROM)
> -------------- HV API                          -------------- HV API
>    Hypervisor              Native HW              Hypervisor

Although this is about VMI, one should not loose sight of this one here with an unmodified OS on virtualizeable hardware:




I think building this could actually be the driving force that can dictate *a lot* of what happens in 'Hypervisor' and what by that implementation alone is offered to the OS by 'Hypervisor' in terms of components. It would necessarily have to end up being a 'PC emulator'. Parts of that Hypervisor architecture can then also be made available to interface with the ROM shown above - not that this has not been done for Xen, but the Qemu models seem to be very far away in domain 0. Xen in contrast has been optimized for speed. I wonder whether the two goals of performanc and PC emulaton are in fact mutually exclusive.


> _______________________________________________
> Xen-devel mailing list
> Xen-devel@xxxxxxxxxxxxxxxxxxx
> http://lists.xensource.com/xen-devel
Xen-devel mailing list



Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.