mirror of https://gitee.com/openkylin/qemu.git
162 lines
5.8 KiB
Plaintext
162 lines
5.8 KiB
Plaintext
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USB 2.0 Quick Start
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===================
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The QEMU EHCI Adapter can be used with and without companion
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controllers. See below for the companion controller mode.
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When not running in companion controller mode there are two completely
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separate USB busses: One USB 1.1 bus driven by the UHCI controller and
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one USB 2.0 bus driven by the EHCI controller. Devices must be
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attached to the correct controller manually.
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The '-usb' switch will make qemu create the UHCI controller as part of
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the PIIX3 chipset. The USB 1.1 bus will carry the name "usb-bus.0".
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You can use the standard -device switch to add a EHCI controller to
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your virtual machine. It is strongly recommended to specify an ID for
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the controller so the USB 2.0 bus gets a individual name, for example
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'-device usb-ehci,id=ehci". This will give you a USB 2.0 bus named
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"ehci.0".
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I strongly recommend to also use -device to attach usb devices because
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you can specify the bus they should be attached to this way. Here is
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a complete example:
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qemu -M pc ${otheroptions} \
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-drive if=none,id=usbstick,file=/path/to/image \
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-usb \
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-device usb-ehci,id=ehci \
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-device usb-tablet,bus=usb-bus.0 \
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-device usb-storage,bus=ehci.0,drive=usbstick
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This attaches a usb tablet to the UHCI adapter and a usb mass storage
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device to the EHCI adapter.
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Companion controller support
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----------------------------
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Companion controller support has been added recently. The operational
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model described above with two completely separate busses still works
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fine. Additionally the UHCI and OHCI controllers got the ability to
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attach to a usb bus created by EHCI as companion controllers. This is
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done by specifying the masterbus and firstport properties. masterbus
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specifies the bus name the controller should attach to. firstport
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specifies the first port the controller should attach to, which is
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needed as usually one ehci controller with six ports has three uhci
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companion controllers with two ports each.
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There is a config file in docs which will do all this for you, just
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try ...
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qemu -readconfig docs/ich9-ehci-uhci.cfg
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... then use "bus=ehci.0" to assign your usb devices to that bus.
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xhci controller support
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-----------------------
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There is also xhci host controller support available. It got a lot
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less testing than ehci and there are a bunch of known limitations, so
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ehci may work better for you. On the other hand the xhci hardware
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design is much more virtualization-friendly, thus xhci emulation uses
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less resources (especially cpu). If you want to give xhci a try
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use this to add the host controller ...
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qemu -device nec-usb-xhci,id=xhci
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... then use "bus=xhci.0" when assigning usb devices.
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More USB tips & tricks
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======================
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Recently the usb pass through driver (also known as usb-host) and the
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qemu usb subsystem gained a few capabilities which are available only
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via qdev properties, i,e. when using '-device'.
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physical port addressing
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------------------------
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First you can (for all usb devices) specify the physical port where
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the device will show up in the guest. This can be done using the
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"port" property. UHCI has two root ports (1,2). EHCI has four root
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ports (1-4), the emulated (1.1) USB hub has eight ports.
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Plugging a tablet into UHCI port 1 works like this:
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-device usb-tablet,bus=usb-bus.0,port=1
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Plugging a hub into UHCI port 2 works like this:
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-device usb-hub,bus=usb-bus.0,port=2
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Plugging a virtual usb stick into port 4 of the hub just plugged works
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this way:
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-device usb-storage,bus=usb-bus.0,port=2.4,drive=...
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You can do basically the same in the monitor using the device_add
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command. If you want to unplug devices too you should specify some
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unique id which you can use to refer to the device ...
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(qemu) device_add usb-tablet,bus=usb-bus.0,port=1,id=my-tablet
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(qemu) device_del my-tablet
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... when unplugging it with device_del.
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USB pass through hints
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----------------------
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The usb-host driver has a bunch of properties to specify the device
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which should be passed to the guest:
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hostbus=<nr> -- Specifies the bus number the device must be attached
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to.
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hostaddr=<nr> -- Specifies the device address the device got
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assigned by the guest os.
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hostport=<str> -- Specifies the physical port the device is attached
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to.
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vendorid=<hexnr> -- Specifies the vendor ID of the device.
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productid=<hexnr> -- Specifies the product ID of the device.
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In theory you can combine all these properties as you like. In
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practice only a few combinations are useful:
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(1) vendorid+productid -- match for a specific device, pass it to
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the guest when it shows up somewhere in the host.
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(2) hostbus+hostport -- match for a specific physical port in the
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host, any device which is plugged in there gets passed to the
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guest.
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(3) hostbus+hostaddr -- most useful for ad-hoc pass through as the
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hostaddr isn't stable, the next time you plug in the device it
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gets a new one ...
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Note that USB 1.1 devices are handled by UHCI/OHCI and USB 2.0 by
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EHCI. That means a device plugged into the very same physical port
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may show up on different busses depending on the speed. The port I'm
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using for testing is bus 1 + port 1 for 2.0 devices and bus 3 + port 1
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for 1.1 devices. Passing through any device plugged into that port
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and also assign them to the correct bus can be done this way:
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qemu -M pc ${otheroptions} \
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-usb \
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-device usb-ehci,id=ehci \
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-device usb-host,bus=usb-bus.0,hostbus=3,hostport=1 \
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-device usb-host,bus=ehci.0,hostbus=1,hostport=1
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enjoy,
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Gerd
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--
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Gerd Hoffmann <kraxel@redhat.com>
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