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+
+USB 2.0 Quick Start
+===================
+
+The QEMU EHCI Adapter does *not* support companion controllers. That
+implies there are two completely separate USB busses: One USB 1.1 bus
+driven by the UHCI controller and one USB 2.0 bus driven by the EHCI
+controller. Devices must be attached to the correct controller
+manually.
+
+The '-usb' switch will make qemu create the UHCI controller as part of
+the PIIX3 chipset. The USB 1.1 bus will carry the name "usb.0".
+
+You can use the standard -device switch to add a EHCI controller to
+your virtual machine. It is strongly recommended to specify an ID for
+the controller so the USB 2.0 bus gets a individual name, for example
+'-device usb-ehci,id=ehci". This will give you a USB 2.0 bus named
+"ehci.0".
+
+I strongly recomment to also use -device to attach usb devices because
+you can specify the bus they should be attached to this way. Here is
+a complete example:
+
+ qemu -M pc ${otheroptions} \
+ -drive if=none,id=usbstick,file=/path/to/image \
+ -usb \
+ -device usb-ehci,id=ehci \
+ -device usb-tablet,bus=usb.0 \
+ -device usb-storage,bus=ehci.0,drive=usbstick
+
+This attaches a usb tablet to the UHCI adapter and a usb mass storage
+device to the EHCI adapter.
+
+enjoy,
+ Gerd
+
+--
+Gerd Hoffmann <kraxel@redhat.com>