95c94f8968
In commit 5cc194caeb,
the number of ehci ports is corrected to six. Fix docs
related to it.
Signed-off-by: npes87184 <npes87184@gmail.com>
Message-id: 20180801122410.10343-1-npes87184@gmail.com
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
173 lines
6.2 KiB
Plaintext
173 lines
6.2 KiB
Plaintext
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USB Quick Start
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===============
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XHCI controller support
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-----------------------
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QEMU has XHCI host adapter support. The XHCI hardware design is much
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more virtualization-friendly when compared to EHCI and UHCI, thus XHCI
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emulation uses less resources (especially cpu). So if your guest
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supports XHCI (which should be the case for any operating system
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released around 2010 or later) we recommend using it:
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qemu -device qemu-xhci
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XHCI supports USB 1.1, USB 2.0 and USB 3.0 devices, so this is the
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only controller you need. With only a single USB controller (and
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therefore only a single USB bus) present in the system there is no
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need to use the bus= parameter when adding USB devices.
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EHCI controller support
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-----------------------
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The QEMU EHCI Adapter supports USB 2.0 devices. It can be used either
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standalone or with companion controllers (UHCI, OHCI) for USB 1.1
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devices. The companion controller setup is more convenient to use
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because it provides a single USB bus supporting both USB 2.0 and USB
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1.1 devices. See next section for details.
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When running EHCI in standalone mode you can add UHCI or OHCI
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controllers for USB 1.1 devices too. Each controller creates its own
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bus though, so there are two completely separate USB buses: One USB
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1.1 bus driven by the UHCI controller and one USB 2.0 bus driven by
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the EHCI controller. Devices must be attached to the correct
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controller manually.
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The easiest way to add a UHCI controller to a 'pc' machine is the
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'-usb' switch. QEMU will create the UHCI controller as function 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 an 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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When adding USB devices using the -device switch you can specify the
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bus they should be attached to. Here is 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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The UHCI and OHCI controllers can attach to a USB bus created by EHCI
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as companion controllers. This is done by specifying the masterbus
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and firstport properties. masterbus specifies the bus name the
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controller should attach to. firstport specifies the first port the
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controller should attach to, which is needed as usually one EHCI
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controller with six ports has three UHCI companion controllers with
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two ports each.
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There is a config file in docs which will do all this for
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you, just try ...
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qemu -readconfig docs/config/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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Using the '-usb' switch for 'q35' machines will create a similar
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USB controller configuration.
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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 six root
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ports (1-6), 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 buses 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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