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  1. aa3120f virtual-usb-printer: add ADF out of documents case by Paul Moy · 10 days ago master release-R90-13816.B stabilize-13799.B
  2. 4ac47f8 virtual-usb-printer: add delayed scan responses by Paul Moy · 2 weeks ago stabilize-rust-13795.B
  3. acec76f virtual-usb-printer: support 2-page ADF scan by Paul Moy · 2 weeks ago
  4. 40a7ae5 virtual-usb-printer: update default configuration by Paul Moy · 3 weeks ago
  5. aad16b9 virtual-usb-printer: support 1-page ADF scans by Paul Moy · 3 weeks ago

Virtual USB Printer

Virtual USB Printer provides a server which can be used with USBIP in order to emulate a USB printing device and bind it to the system as if it were physically connected to a USB port.

Virtual USB Printer supports both regular USB printers as well as IPP-over-USB devices.


This project was created in order to make on-device tests which check for any regressions in the native USB printing system.


  • USBIP - userspace program for binding virtual device to system
  • USBIP kernel modules:

In order to actually “connect” the virtual printer to the system the USBIP program is used.

USBIP is typically used to export real USB devices over a network so that other systems on the network can bind them and treat them as connected devices.

For the purposes of the virtual printer, only the client portion of USBIP is required so that the virtual device can be bound to the system.


Currently the USBIP program is only installed by default for the elm and betty boards.

In order to install it on your test image, you need to build an image with the usbip USE flag enabled. To do this, all you need to to is run build_packages with the USE flag enabled.

USE="usbip" ./build_packages --board=$BOARD

How to Use

Before the first use you have to load a required kernel module:

modprobe vhci-hcd

Run the virtual-usb-printer program:

virtual-usb-printer --descriptors_path=<path>

(Optional) Check the list of exported printers with USBIP:

usbip list -r localhost

Should return something like this:

Exportable USB devices
 - localhost
        1-1: Canon, Inc. : unknown product (04a9:27e8)
           : /sys/devices/pci0000:00/0000:00:01.2/usb1/1-1
           : (Defined at Interface level) (00/00/00)
           : 0 - Printer / Printer Bidirectional (07/01/02)

Bind the virtual printer to the system:

usbip attach -r localhost -b 1-1

Once the device has been attached it should appear in the list of connected USB devices (lsusb), and can be used with the native printing system in Chrome OS.


The printer's USB descriptors and defined IPP attributes can be configured using a JSON file and are loaded at run-time using command line flags. Example configurations can be found in the config/ directory.

The configuration files can be loaded with the following flags:

  • --descriptors_path - full path to the JSON file which defines the USB descriptors
  • --attributes_path - full path to the JSON file which defines the supported IPP attributes
    • Only needed for IPP-over-USB printer configurations
  • --record_doc_path - full path to the file used to record documents received from print jobs

Using in Tast

There are currently existing tast tests which leverage virtual-usb-printer in order to test native printing. The following can be used as examples in order to write new tests:

  • Add USB Printer
    • Tests that adding a basic USB printer works correctly
  • Print USB
    • Tests that the full print pipeline works correctly for a basic USB printer
  • Print IPPUSB
    • Tests that the full print pipeline for IPP-over-USB printing works correctly
    • This also tests that the automatic_usb_printer_configurer is able to automatically configure an IPP everywhere printer