audio, disk, ether, kb, serial, ptp, usbd - Universal Serial Bus drivers


nusb/audio devid

nusb/disk [ -d ] devid

nusb/ether [ -dD ] [ -t ethertype ] [ -a addr ] devid

nusb/kb [ -d ] devid

nusb/serial [ -d ] devid

nusb/ptp [ -dD ] devid

nusb/usbd [ -dD ]


These programs drive USB devices of specific classes via usb(3). Usually they are started by nusbrc(8) upon attachment of the device to the bus. All drivers except usbd take the decimal usb devid of the device they should handle as ther last argument. A driver’s instance handles only one device at a time.

Drivers that provide file systems make them available as shares under /shr (see shr(3)) or /shr/usb (which is bound after /dev by nusbrc(8)).

Options –d and –D trigger debug diagnostics and file system debugging diagnostics for most drivers. Repeating any one of these may increase verbosity.


Usbd enumerates the tree of USB hubs and configures the device on attachment. It provides a filesystem with the file usbevent (usually seen as /dev/usbevent) which, when read, returns a 6 column, space separated line of text, one for each event. The columns are: attach or detach followed by addr vid did csp and hname . The addr is the decimal device address assigned. Vid and did are formatted as 4 digit hexadecimal. Csp is the device class, subclass, protocol indentifier formatd as 6 digit hexadecimal. Usbd assigns a stable device unique name based on the device descriptor for hname . This information is read by nusbrc(8) and the addr and hname are passed to a suitable driver as devid in the form addr:hname

Keyboards and mice

Kb supports USB keyboards and mice either as separate USB devices or as a single combined USB device. Scan codes from the keyboard are sent to /dev/kbin to let kbdfs(8) process them. Mouse events are sent to /dev/mousein in the same way.


Disk configures and manages USB mass storage devices. It provides a file system (usually seen under /dev) that includes one directory per storage device, named sdUN[.M] in correspondence with the usb device unique name and the storage unit number (or LUN). The LUN is omited for single lun devices.

The storage device directory contains the usual files served by sd(3): data, raw, and ctl.

The ctl file supplies the device geometry and partitions when read.


Ether handles USB ethernet devices. The file system provided is compatible to ether(3) and added to the share usbnet (see shr(3)) which is bound after /net by nusbrc(8) so the device will appear as /net/etherUN. Without specifying the -t option, the device is assumed to be a CDC compliant ethernet communication device. Other devices might require setting an explicit ethertype, such as rndis, smsc, a88772 or a88178 (see nusbrc(8)). On devices that support it, the mac address can be set using the -a addr option.

Serial and JTAG ports

Serial provides a file system (usually seen under /dev) that includes one directory per USB serial port, named eiaUN or eiaUN[.M]. In this directory there are two files, eiaU, similar to eiaN in uart(3), and eiaUctl, which admits writes in the same format as eiaNctl in uart(3). Reading from eiaUctl gives the serial port’s settings in the same format as eiaNstatus in uart(3). Options are similar to those of disk.

JTAG ports are similar but the files are named jtag and jtagctl.

Audio devices

Audio configures and manages a USB audio device. It implements a file system, (normally seen under /dev) compatible to audio(3).




audio(3), ether(3), mouse(3), sd(3), uart(3), usb(3), shr(3), nusbrc(8), kbdfs(8)


The various device drivers are generic USB drivers and may work only for certain devices of each class.

USB ATA storage devices are not supported.

The serial driver works only for the Prolific chip and Ftdi, and control of the dcd and dsr signals and some of the extra features are not implemented. For Ftdi, only the Sheevaplug and Guruplug have been tried. There is support for the EHCI debug port, but it loses bytes.