Copyright (c) 1986 Regents of the University of California.
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@(#)enp.4 5.1 (Berkeley) 12/12/87

C 5 enp - 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 interface code reads the buffer contents directly through the VERSAbus. The address of this memory is derived from the address specified in the configuration file.

Each of the host's network addresses is specified at boot time with an SIOCSIFADDR ioctl. The ace interface employs the address resolution protocol described in arp (4P) to dynamically map between Internet and Ethernet 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 setting 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 dropped. intro(4N), inet(4F), arp(4P), enpload(8C) The hardware is not capable of talking to itself. The software implements 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 address.