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

On Thu, 20 Sep 2012, Pawel Moll wrote:

On Thu, 2012-09-20 at 12:39 +0100, Stefano Stabellini wrote:

quoted

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 at 80000000 and gic at 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.