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.
As of https://crrev.com/c/3093381,
virtual-usb-printer is built and installed by default on all test images that support it.
If for some reason you need to build it yourself, you can
USE=usbip when building packages for your board - i.e.
USE="usbip" ./build_packages --board=$BOARD
usbipto manifest as a virtual USB device. Most test images seem to come with this built-in by default. If you need to build your own kernel with
usbipsupport, make sure to build with
virtual-usb-printer can behave like
For ease of human operation, start
virtual-usb-printer via its Upstart unit. Pass the appropriate arguments to the invocation as needed.
For example, to start and connect the
virtual-usb-printer as an IPP-over-USB printer, issue
start virtual-usb-printer USB_DESCRIPTORS=ippusb_printer.json IPP_ATTRIBUTES=ipp_attributes.json
Consult the Upstart config file to see the arguments understood in this context.
virtual-usb-printersends its output to the system log.
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
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
--record_doc_path- full path to the file used to record documents received from print jobs
--output_log_dir- directory path specifying where scan settings will be logged
Refer to these existing tast tests for examples of how to use the
virtual-usb-printer to test the Chromium OS printing stack.