Re: [Xen-devel] [RFC PATCH v2 3/3] tools, libxl: handle the iomem parameter with the memory_mapping hcall

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Fri, 2014-03-14 at 16:45 +0100, Dario Faggioli wrote:

> > > To me, a legitimate use case is this: I want to run version X of my non
> > > DT capable OS on version Z of Xen, on release K of board B. In such
> > > configuration, the GPIO controller is at MFN 0x000abcd, and I want only
> > > VM V to have direct access to it (board B dos not have an IOMMU).
> > > 
> > > I would also assume that one is in full control of the guest address
> > 
> > If "one" here is the user then I don't think so.
> > 
> Well, fact is "user", in this context, is who puts the embedded system
> together into a product, rather than folks actually using such product,
> so, I don't see that much unlikely.

I don't imagine even those folks are going to want to hack the
hypervisor to change the guest address space layout, so I don't think
you can assume they have full control, they will get whatever the layout
for that version of Xen is. They do control the hypervisor version so I
suppose they control in that sense.

If they *are* hacking the hypervisor to fiddle with the guest addres
space then they have no need for this toolstack integration feature,
they can (and likely will) just bodge it in the same place.

Ian.




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