I'm writing a program for controlling USB storage device connections (this is a classic subject). All it's ok with my program, but now, I want to write some tests. So in order to do that, I realized I'll need some way of simulate USB connections.

And not only the connections, I need to be able to set the device properties: capacity, format, etc...

  • what has the USB simulation to do with qemu?
    – user55518
    Mar 12, 2014 at 22:04
  • Well... I saw into systemd code (freedesktop.org/wiki/Software/systemd) that they usit for tests on udev. I then make the conclusion that they must be using qemu to simulate some "hardware thigns." Mar 13, 2014 at 12:11
  • How ever if you know other way for doing that, I'll thank you point me the right direction. Mar 13, 2014 at 12:11
  • well, qemu/kvm is good for testing. in case of a failure you don't need to reboot. Special usb hardware needs to be forwarded to qemu/kvm with usb_add. I am not up to date with the latest dev, so I can't tell you.
    – user55518
    Mar 13, 2014 at 14:09

1 Answer 1


I found the solution here: USB emulation

3.11 USB emulation

QEMU emulates a PCI UHCI USB controller. You can virtually plug virtual USB devices or real host USB devices (experimental, works only on Linux hosts). QEMU will automatically create and connect virtual USB hubs as necessary to connect multiple USB devices.

3.11.1 Connecting USB devices

USB devices can be connected with the -usbdevice commandline option or the usb_add monitor command. Available devices are:

mouse Virtual Mouse. This will override the PS/2 mouse emulation when activated.

tablet Pointer device that uses absolute coordinates (like a touchscreen). This means QEMU is able to report the mouse position without having to grab the mouse. Also overrides the PS/2 mouse emulation when activated.

disk:file Mass storage device based on file (see disk_images)

host:bus.addr Pass through the host device identified by bus.addr (Linux only)

host:vendor_id:product_id Pass through the host device identified by vendor_id:product_id (Linux only)

wacom-tablet Virtual Wacom PenPartner tablet. This device is similar to the tablet above but it can be used with the tslib library because in addition to touch coordinates it reports touch pressure.

keyboard Standard USB keyboard. Will override the PS/2 keyboard (if present).

serial:[vendorid=vendor_id][,product_id=product_id]:dev Serial converter. This emulates an FTDI FT232BM chip connected to host character device dev. The available character devices are the same as for the -serial option. The vendorid and productid options can be used to override the default 0403:6001. For instance,

usb_add serial:productid=FA00:tcp: will connect to tcp port 4444 of ip, and plug that to the virtual serial converter, faking a Matrix Orbital LCD Display (USB ID 0403:FA00).

braille Braille device. This will use BrlAPI to display the braille output on a real or fake device.

net:options Network adapter that supports CDC ethernet and RNDIS protocols. options specifies NIC options as with -net nic,options (see description). For instance, user-mode networking can be used with

qemu-system-i386 [...OPTIONS...] -net user,vlan=0 -usbdevice net:vlan=0 Currently this cannot be used in machines that support PCI NICs.

bt[:hci-type] Bluetooth dongle whose type is specified in the same format as with the -bt hci option, see allowed HCI types. If no type is given, the HCI logic corresponds to -bt hci,vlan=0. This USB device implements the USB Transport Layer of HCI. Example usage:

qemu-system-i386 [...OPTIONS...] -usbdevice bt:hci,vlan=3 -bt device:keyboard,vlan=3

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