Re: [Xen-devel] [PATCH] arm: introduce a DTS for Xen unprivileged virtual machines

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Thu, 20 Sep 2012, Pawel Moll wrote:
> On Thu, 2012-09-20 at 12:39 +0100, Stefano Stabellini wrote:
> > There are no peripherals apart from the ones that are already described
> > here (timer, gic). All the peripherals that the guest sees are virtual
> > devices that show up on xenbus (a virtual bus). In order to initialize
> > xenbus, the guest only needs the hypervisor node.  So I'll remove the
> > ranges and interrupt-map.
> 
> So all the peripherals are actually discoverable - awesome!
> 
> But the fact is that the only "vexpressness" of this tree is
> memory@80000000 and gic@2c001000. The rest (not much of it ;-) is a
> "generic A15 platform". 
> 
> I understand that you had to use some "compatible" value to get
> initialization code and I'm flattered ;-) by your choice of
> "arm,vexpress", but maybe - as suggested by others - you would be better
> off with generating this stuff in runtime, by whatever tool is used to
> instantiate the guest?

Yes, it is certainly going to be generated at run time. Does it make
sense to keep an example under arch/arm/boot/dts? I think so. There must
be other platforms that actually pass the device tree to the kernel from
the firmware and still have a dts in the kernel tree, right?
If actually there are none, it is probably best to forget about this
patch :)

Regarding the choice of "arm,vexpress", there was a discussion at kernel
summit about vexpress being the right choice as a base platform for
virtual machines on ARM, even though in the Xen case it means having a
vexpress with no peripherals.

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