ENP(4) BSD/tahoe Kernel Interfaces Manual ENP(4)NAMEenp — CMC 10 Mb/s Ethernet interface
device enp0 at vba? csr 0xfff40000 vector enpintr
The enp interface provides access to a 10 Mb/s Ethernet network through a
CMC ENP-20 controller.
The hardware has 128 kilobytes of dual-ported memory on the VERSAbus.
This memory is used for internal buffering by the board, and the inter‐
face code reads the buffer contents directly through the VERSAbus. The
address of this memory is derived from the address specified in the con‐
Each of the host's network addresses is specified at boot time with an
SIOCSIFADDR ioctl(2). The enp interface employs the address resolution
protocol described in arp(4) to dynamically map between Internet and Eth‐
ernet addresses on the local network.
The interface normally tries to use a “trailer” encapsulation to minimize
copying data on input and output. The use of trailers is negotiated with
ARP. This negotiation may be disabled, on a per-interface basis, by set‐
ting the IFF_NOTRAILERS flag with an SIOCSIFFLAGS ioctl.
Associated with each interface is a character device which is used to
dowload, start, and reset the firmware in the controller. Reading or
writing the “ram device” reads or writes the writable control store in
the controller. Two ioctl(2) calls, ENPIOGO and ENPIORESET, are used to
start and reset the firmware.
enp%d: can't handle af%d. The interface was handed a message with
addresses formatted in an unsuitable address family; the packet was
SEE ALSOintro(4), inet(4), arp(4), enpload(8)HISTORY
The enp driver appeared in 4.3BSD-Tahoe.
The hardware is not capable of talking to itself. The software imple‐
ments local sending and broadcast by sending such packets to the loop
interface. This is a kludge.
The link level firmware does not support setting the board's Ethernet
4.3-Tahoe Berkeley Distribution June 5, 1993 4.3-Tahoe Berkeley Distribution