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

On Thu, 20 Sep 2012, Pawel Moll wrote:

Morning,

On Wed, 2012-09-19 at 18:44 +0100, Stefano Stabellini wrote:

quoted

+/dts-v1/;
+
+/include/ "skeleton.dtsi"

Any particular reason to include skeleton? And I think it would be
better to use #address-cells = <2> and #size-cells = <2>, to be ready
for LPAE addresses...

good idea

quoted

+/ {
+	model = "XENVM-4.2";
+	compatible = "xen,xenvm-4.2", "arm,vexpress";
+	interrupt-parent = <&gic>;
+
+	chosen {
+		bootargs = "earlyprintk console=hvc0 root=/dev/xvda init=/sbin/init";
+	};
+
+	cpus {
+		#address-cells = <1>;
+		#size-cells = <0>;
+
+		cpu at 0 {
+			device_type = "cpu";
+			compatible = "arm,cortex-a15";
+			reg = <0>;
+		};
+	};
+
+	memory {

Formally, it should be memory at 80000000, not that I have any strong
feelings about it :-)

OK

quoted

+		device_type = "memory";
+		reg = <0x80000000 0x08000000>;
+	};
+
+	gic: interrupt-controller at 2c001000 {
+		compatible = "arm,cortex-a9-gic";
+		#interrupt-cells = <3>;
+		#address-cells = <0>;
+		interrupt-controller;
+		reg = <0x2c001000 0x1000>,
+		      <0x2c002000 0x100>;
+	};
+
+	timer {
+		compatible = "arm,armv7-timer";
+		interrupts = <1 13 0xf08>,
+			     <1 14 0xf08>,
+			     <1 11 0xf08>,
+			     <1 10 0xf08>;
+	};
+
+	hypervisor {
+		compatible = "xen,xen-4.2", "xen,xen";
+		reg = <0xb0000000 0x20000>;
+		interrupts = <1 15 0xf08>;
+	};

Is this binding documented somewhere - I mean in
Documentation/devicetree/bindings?

Yes, it is: Documentation/devicetree/bindings/arm/xen.txt
added by: http://marc.info/?l=linux-kernel&m=134790380030990&w=2

quoted

+	motherboard {
+		arm,v2m-memory-map = "rs1";
+		ranges = <0 0 0x08000000 0x04000000>,
+			 <1 0 0x14000000 0x04000000>,
+			 <2 0 0x18000000 0x04000000>,
+			 <3 0 0x1c000000 0x04000000>,
+			 <4 0 0x0c000000 0x04000000>,
+			 <5 0 0x10000000 0x04000000>;
+
+		interrupt-map-mask = <0 0 63>;
+		interrupt-map = <0 0  0 &gic 0  0 4>,
+				<0 0  1 &gic 0  1 4>,
+				<0 0  2 &gic 0  2 4>,
+				<0 0  3 &gic 0  3 4>,
+				<0 0  4 &gic 0  4 4>,
+				<0 0  5 &gic 0  5 4>,
+				<0 0  6 &gic 0  6 4>,
+				<0 0  7 &gic 0  7 4>,
+				<0 0  8 &gic 0  8 4>,
+				<0 0  9 &gic 0  9 4>,
+				<0 0 10 &gic 0 10 4>,
+				<0 0 11 &gic 0 11 4>,
+				<0 0 12 &gic 0 12 4>,
+				<0 0 13 &gic 0 13 4>,
+				<0 0 14 &gic 0 14 4>,
+				<0 0 15 &gic 0 15 4>,
+				<0 0 16 &gic 0 16 4>,
+				<0 0 17 &gic 0 17 4>,
+				<0 0 18 &gic 0 18 4>,
+				<0 0 19 &gic 0 19 4>,
+				<0 0 20 &gic 0 20 4>,
+				<0 0 21 &gic 0 21 4>,
+				<0 0 22 &gic 0 22 4>,
+				<0 0 23 &gic 0 23 4>,
+				<0 0 24 &gic 0 24 4>,
+				<0 0 25 &gic 0 25 4>,
+				<0 0 26 &gic 0 26 4>,
+				<0 0 27 &gic 0 27 4>,
+				<0 0 28 &gic 0 28 4>,
+				<0 0 29 &gic 0 29 4>,
+				<0 0 30 &gic 0 30 4>,
+				<0 0 31 &gic 0 31 4>,
+				<0 0 32 &gic 0 32 4>,
+				<0 0 33 &gic 0 33 4>,
+				<0 0 34 &gic 0 34 4>,
+				<0 0 35 &gic 0 35 4>,
+				<0 0 36 &gic 0 36 4>,
+				<0 0 37 &gic 0 37 4>,
+				<0 0 38 &gic 0 38 4>,
+				<0 0 39 &gic 0 39 4>,
+				<0 0 40 &gic 0 40 4>,
+				<0 0 41 &gic 0 41 4>,
+				<0 0 42 &gic 0 42 4>;
+	};
+};

You've lost me here... You have ranges and interrupt map, but don't
include motherboard file. Is it a mistake? If not, you could remove the
ranges and interrupt-map, but where do you get your peripherals from
then?

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.