[Xen-devel] [PATCH v4 33/33] docs/misc: arm: Add documentation about non-PCI passthrough

[Julien Grall <julien.grall@xxxxxxxxxx>]

Note that the example is done on Midway whose SMMU driver is not
supported on Xen upstream.

Currently, I don't have other platform where I can test non-PCI
passthrough.

Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>

---
    Changes in v4:
        - Patch added
---
 docs/misc/arm/passthrough.txt | 58 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 58 insertions(+)
 create mode 100644 docs/misc/arm/passthrough.txt

diff --git a/docs/misc/arm/passthrough.txt b/docs/misc/arm/passthrough.txt
new file mode 100644
index 0000000..cf6cc61
--- /dev/null
+++ b/docs/misc/arm/passthrough.txt
@@ -0,0 +1,58 @@
+Passthrough a non-pci device to a guest
+=======================================
+
+The example will use the secondary network card for the midway server.
+
+1) Mark the device to let Xen knowns the device will be used for passthrough.
+This is done in the device tree node describing the device by adding the
+property "xen,passthrough". The command to do it in U-Boot is:
+
+    fdt set /soc/ethernet@fff51000 xen,passthrough
+
+2) Create the partial device tree describing the device. The IRQ are mapped
+1:1 to the guest (i.e VIRQ == IRQ). For MMIO will have to find hole in the
+guest memory layout (see xen/include/public/arch-arm.h, noted the layout
+is not stable and can change between 2 releases version of Xen).
+
+/dts-v1/;
+
+/ {
+    /* #*cells are here to keep DTC happy */
+    #address-cells = <2>;
+    #size-cells = <2>;
+
+    aliases {
+        net = &mac0;
+    };
+
+    passthrough {
+        compatible = "simple-bus";
+        ranges;
+        #address-cells = <2>;
+        #size-cells = <2>;
+       mac0: ethernet@10000000 {
+               compatible = "calxeda,hb-xgmac";
+            reg = <0 0x10000000 0 0x1000>;
+               interrupts = <0 80 4  0 81 4  0 82 4>;
+       };
+    };
+};
+
+Note:
+    * The interrupt-parent property will be added by the toolstack in the
+    root node;
+    * The properties compatible, ranges, #address-cells and #size-cells
+    in /passthrough are mandatory.
+
+3) Compile the partial guest device with dtc (Device Tree Compiler).
+For our purpose, the compiled file will be called guest-midway.dtb and
+placed in /root in DOM0.
+
+3) Add the following options in the guest configuration file:
+
+device_tree = "/root/guest-midway.dtb"
+dtdev = [ "/soc/ethernet@fff51000" ]
+irqs = [ 112, 113, 114 ]
+iomem = [ "0xfff51,1@0x10000" ]
+
+
-- 
2.1.4


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