3.11. USB support

3.11.1. USB settings

The "USB" section in a virtual machine's Settings window allows you to configure VirtualBox's sophisticated USB support.

VirtualBox can allow virtual machines to access the USB devices on your host directly. To achieve this, VirtualBox presents the guest operating system with a virtual USB controller. As soon as the guest system starts using a USB device, it will appear as unavailable on the host.

Note

Be careful with USB devices that are currently in use on the host! For example, if you allow your guest to connect to your USB hard disk that is currently mounted on the host, when the guest is activated, it will be disconnected from the host without a proper shutdown. This may cause data loss.
Solaris hosts have a few known limitations regarding USB support; please see Chapter 14, Known limitations.

In addition to allowing a guest access to your local USB devices, VirtualBox even allows your guests to connect to remote USB devices by use of the VirtualBox Remote Desktop Extension (VRDE). For details about this, see Section 7.1.4, “Remote USB”.

In the Settings dialog, you can first configure whether USB is available in the guest at all, and then choose the level of USB support: OHCI for USB 1.1, EHCI (which will also enable OHCI) for USB 2.0, or xHCI for all USB speeds.

Note

The xHCI and EHCI controllers are shipped as a VirtualBox extension package, which must be installed separately. See Section 1.5, “Installing VirtualBox and extension packs” for more information.

When USB support is enabled for a VM, you can determine in detail which devices will be automatically attached to the guest. For this, you can create so-called "filters" by specifying certain properties of the USB device. USB devices with a matching filter will be automatically passed to the guest once they are attached to the host. USB devices without a matching filter can be passed manually to the guest, for example by using the Devices / USB devices menu.

Clicking on the "+" button to the right of the "USB Device Filters" window creates a new filter. You can give the filter a name (for referencing it later) and specify the filter criteria. The more criteria you specify, the more precisely devices will be selected. For instance, if you specify only a vendor ID of 046d, all devices produced by Logitech will be available to the guest. If you fill in all fields, on the other hand, the filter will only apply to a particular device model from a particular vendor, and not even to other devices of the same type with a different revision and serial number.

In detail, the following criteria are available:

Vendor and product ID. With USB, each vendor of USB products carries an identification number that is unique world-wide, the "vendor ID". Similarly, each line of products is assigned a "product ID" number. Both numbers are commonly written in hexadecimal (that is, they are composed of the numbers 0-9 and the letters A-F), and a colon separates the vendor from the product ID. For example, 046d:c016 stands for Logitech as a vendor, and the "M-UV69a Optical Wheel Mouse" product.

Alternatively, you can also specify "Manufacturer" and "Product" by name.

To list all the USB devices that are connected to your host machine with their respective vendor and product IDs, you can use the following command (see Chapter 8, VBoxManage):
```
VBoxManage list usbhost
```
On Windows, you can also see all USB devices that are attached to your system in the Device Manager. On Linux, you can use the lsusb command.
Serial number. While vendor and product ID are already quite specific to identify USB devices, if you have two identical devices of the same brand and product line, you will also need their serial numbers to filter them out correctly.
Remote. This setting specifies whether the device will be local only, or remote only (over VRDP), or either.

On a Windows host, you will need to unplug and reconnect a USB device to use it after creating a filter for it.

As an example, you could create a new USB filter and specify a vendor ID of 046d (Logitech, Inc), a manufacturer index of 1, and "not remote". Then any USB devices on the host system produced by Logitech, Inc with a manufacturer index of 1 will be visible to the guest system.

Several filters can select a single device -- for example, a filter which selects all Logitech devices, and one which selects a particular webcam.

You can deactivate filters without deleting them by clicking in the checkbox next to the filter name.

3.11.2. Implementation notes for Windows and Linux hosts

On Windows hosts, a kernel mode device driver provides USB proxy support. It implements both a USB monitor, which allows VirtualBox to capture devices when they are plugged in, and a USB device driver to claim USB devices for a particular virtual machine. As opposed to VirtualBox versions before 1.4.0, system reboots are no longer necessary after installing the driver. Also, you no longer need to replug devices for VirtualBox to claim them.

On newer Linux hosts, VirtualBox accesses USB devices through special files in the file system. When VirtualBox is installed, these are made available to all users in the vboxusers system group. In order to be able to access USB from guest systems, make sure that you are a member of this group.

On older Linux hosts, USB devices are accessed using the usbfs file system. Therefore, the user executing VirtualBox needs read and write permission to the USB file system. Most distributions provide a group (e.g. usbusers) which the VirtualBox user needs to be added to. Also, VirtualBox can only proxy to virtual machines USB devices which are not claimed by a Linux host USB driver. The Driver= entry in /proc/bus/usb/devices will show you which devices are currently claimed. Please refer to Section 12.8.7, “USB not working” also for details about usbfs.