I picked up a Zebra LP2844 cheap off of eBay today...tested it at work under Windows 10, and now I want to get it running at home under Gentoo Linux. CUPS is built with libusb support and /usr/libexec/cups/backend/usb finds the printer and returns usb://Zebra/LP2844?serial=42A062401950 as the printer URL. lpinfo -v shows no indication of the printer, though, and "Find New Printers" in the CUPS web interface returns nothing.

If I enable CONFIG_USB_PRINTING in the kernel source and recompile, plugging in the printer now causes it to show up at /dev/usb/lp0. I can manually configure the printer in CUPS, telling it to print to file:///dev/usb/lp0 (after tweaking /etc/cups/cups-files.conf appropriately), and the test page and a label I knocked together in LibreOffice will priint successfully. If I unload the usblp kernel module and change the printer configuration from the file: URL to the usb: URL, print jobs get stuck. If I reload usblp and change the configuration back to the file: URL, jobs in the queue will finally print.