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Julien Grall
0b24160656
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 Device Tree passthrough. Signed-off-by: Julien Grall <julien.grall@linaro.org> Acked-by: Ian Campbell <ian.campbell@citrix.com>
63 lines
1.9 KiB
Plaintext
63 lines
1.9 KiB
Plaintext
Passthrough a device described in the Device Tree to a guest
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The example will use the secondary network card for the midway server.
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1) Mark the device to let Xen know the device will be used for passthrough.
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This is done in the device tree node describing the device by adding the
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property "xen,passthrough". The command to do it in U-Boot is:
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fdt set /soc/ethernet@fff51000 xen,passthrough
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2) Create a partial device tree describing the device. The IRQ are mapped
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1:1 to the guest (i.e VIRQ == IRQ). For MMIO, you will have to find a hole
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in the guest memory layout (see xen/include/public/arch-arm.h, note that
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the layout is not stable and can change between versions of Xen).
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/dts-v1/;
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/ {
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/* #*cells are here to keep DTC happy */
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#address-cells = <2>;
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#size-cells = <2>;
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aliases {
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net = &mac0;
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};
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passthrough {
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compatible = "simple-bus";
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ranges;
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#address-cells = <2>;
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#size-cells = <2>;
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mac0: ethernet@10000000 {
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compatible = "calxeda,hb-xgmac";
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reg = <0 0x10000000 0 0x1000>;
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interrupts = <0 80 4 0 81 4 0 82 4>;
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};
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};
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};
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Note:
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* The interrupt-parent property will be added by the toolstack in the
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root node;
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* The following properties are mandatory with the /passthrough node:
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- compatible: It should always contain "simple-bus"
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- ranges
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- #address-cells
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- #size-cells
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* See http://www.devicetree.org/Device_Tree_Usage for more
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information about device tree.
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3) Compile the partial guest device with dtc (Device Tree Compiler).
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For our purpose, the compiled file will be called guest-midway.dtb and
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placed in /root in DOM0.
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3) Add the following options in the guest configuration file:
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device_tree = "/root/guest-midway.dtb"
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dtdev = [ "/soc/ethernet@fff51000" ]
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irqs = [ 112, 113, 114 ]
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iomem = [ "0xfff51,1@0x10000" ]
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