RE: [Xen-devel] Re: Are linker scripts needed?

["Ian Pratt" <m+Ian.Pratt@xxxxxxxxxxxx>]

> > Major benefit of your approach, from my thought, is that backend 
> > driver in service OS can service both para-virtualization and 
> > full-firtualization domain then, with a unified channel 
> interface and 
> > logic, right? I'm trying to understand how 'virtual smm mode' you 
> > mentioned can be achieved, and thinking at least following 
> > modifications may be required:
> 
> I thought that VMX provided a virtual equivalent of SMM, 
> where management and emulation code can run under the OS's 
> feet without it realising? If this is not provided then I do 
> not think the trick can work, as you would need to steal some 
> virtual address space in which to execute the qemu code.

I'd be inclined to move to a model where we execute the device emulation
in the root (monitor) VMCS, using the same protection mechanism we use
for para-virtualized guests e.g. segmentation for x86, paging for
x86_64. The device emulation should should work like a normal front-end
driver, connecting via a device channel to a normal backend.

Infact, I really like this approach. It gives good performance, safety,
code reuse, and unifies the control interface. It does require a bit of
hacking of qemu, to give it the execution environment it needs and make
it connect onto the existing back ends.

Arguments against?

Ian

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