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CM(4)		       FreeBSD Kernel Interfaces Manual			 CM(4)

NAME
     cm	-- SMC Arcnet Ethernet device driver

SYNOPSIS
     To	compile	support	for the
     cm	driver into your kernel, place the following lines in your kernel con-
	figuration file:

	   device isa
	   device cm

	Alternatively, to load the cm(4) driver	at boot	time, place the	fol-
	lowing line in loader.conf(5):

	      if_cm_load="YES"

DESCRIPTION
     The cm driver provides support for	the Arcnet ISA network adapters.

     This driver also has quirks preset	in the device.hints(5) file for	card
     detection.

HARDWARE
     The cm driver supports the	following card models:

     +o	 SMC90c26
     +o	 SMC90c56
     +o	 SMC90c66 in '56 compatibility mode.

IMPLEMENTATION NOTES
     When the NOARP flag is set	on the cm interface, it	does not employ	the
     address resolution	protocol described in arp(4) to	dynamically map
     between Internet and Ethernet addresses on	the local network.  Instead it
     uses the least significant	8 bits of the IP address as the	hardware
     address like described in RFC 1051	and RFC	1201.

     With the IFF_LINK0	flag cleared IP/ARP/RARP encoding is done according to
     RFC 1201 that is, with Packet Header Definition Standard header and
     packet type 212 / 213.  The MTU is	normally 1500.	The IFF_LINK0 flag is
     cleared by	default.

     With the IFF_LINK0	flag set, IP and ARP encoding is done according	to the
     deprecated	RFC 1051 encoding, that	is with	simple header, packet type 240
     / 241, and	the MTU	is 507.

     When switching between the	two modes, use
	   ifconfig interfacename down up
     to	switch the MTU.

DIAGNOSTICS
     The following driver specific error messages may be reported:

     reset: card reset,	link addr = 0x%02x (cm%d)  The card is being reset and
     a new link	address	assigned.

     srint: restarted rx on buf	cm%d  The rx buffer has	been emptied and will
     be	reset.

SEE ALSO
     netintro(4), watchdog(4), device.hints(5),	ifconfig(8), watchdog(8)

HISTORY
     The cm device was ported from NetBSD by Max Khon <fjoe@FreeBSD.org> and
     first appeared in FreeBSD 4.6.  This manual page first appeared in
     FreeBSD 5.3.

AUTHORS
     This manual page was written by Tom Rhodes	<trhodes@FreeBSD.org>.	The
     IMPLEMENTATION NOTES section was submitted	by
     Max Khon <fjoe@FreeBSD.org> and originated	from NetBSD.

BUGS
     The cm driver code	could do with a	bit of improvement, it would be	nice
     if	some one could come along and take care	of this.

     The IMPLEMENTATION	NOTES section is specific to all Arcnet	devices	(see
     sys/net/if_arcsubr.c) and should be moved to a more generic location.

FreeBSD	6.0			 July 23, 2014			   FreeBSD 6.0

NAME | SYNOPSIS | DESCRIPTION | HARDWARE | IMPLEMENTATION NOTES | DIAGNOSTICS | SEE ALSO | HISTORY | AUTHORS | BUGS

Want to link to this manual page? Use this URL:
<http://www.freebsd.org/cgi/man.cgi?query=cm&sektion=4&manpath=FreeBSD+6.0-RELEASE>

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