.\"
.\" Copyright (c) 2004 Tom Rhodes
.\" All rights reserved.
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.\" $FreeBSD$
.\"
.Dd July 16,2005
.Dt CM 4
.Os
.Sh NAME
.Nm cm
.Nd "SMC Arcnet Ethernet device driver"
.Sh SYNOPSIS
To compile support for the
.Nm
driver into your kernel, place the following lines in
your kernel configuration file:
.Bd -ragged -offset indent
.Cd "device isa"
.Cd "device cm"
.Ed
.Pp
Alternatively, to load the
.Xr cm 4
driver at boot time, place the following line in
.Xr loader.conf 5 :
.Bd -literal -offset indent
if_cm_load="YES"
.Ed
.Sh DESCRIPTION
The
.Nm
driver provides support for the
.Tn Arcnet
.Tn ISA
network adapters.
.Pp
This driver also has quirks preset in the
.Xr device.hints 5
file for card detection.
.Sh HARDWARE
The
.Nm
driver supports the following
card models:
.Pp
.Bl -bullet -compact
.It
SMC90c26
.It
SMC90c56
.It
SMC90c66 in '56 compatibility mode.
.El
.Sh IMPLEMENTATION NOTES
When the
.Va NOARP
flag is set on the
.Nm
interface,
it does not employ the address resolution protocol described in
.Xr arp 4
to dynamically map between Internet and Ethernet addresses on
the local network.
Instead it uses the least significant 8 bits of the
.Tn IP
address as the hardware address
like described in
.Tn RFC
1051
and
.Tn RFC
1201.
.Pp
With the
.Dv IFF_LINK0
flag cleared
.Tn IP/ARP/RARP
encoding is done according to
.Tn RFC
1201
that is, with Packet Header Definition Standard header and packet type
212 / 213.
The
.Tn MTU
is normally 1500.
The
.Dv IFF_LINK0
flag is cleared by default.
.Pp
With the
.Dv IFF_LINK0
flag set,
.Tn IP
and
.Tn ARP
encoding is done according to the deprecated
.Tn RFC
1051 encoding, that is with simple header, packet type 240 / 241,
and the
.Tn MTU
is 507.
.Pp
When switching between the two modes, use
.Dl ifconfig interfacename down up
to switch the
.Tn MTU .
.Sh DIAGNOSTICS
The following driver specific error messages
may be reported:
.Bl -diag
.It "reset: card reset, link addr = 0x%02x (cm%d)"
The card is being reset and a new link address assigned.
.It "srint: restarted rx on buf cm%d"
The rx buffer has been emptied and will be reset.
.El
.Sh SEE ALSO
.Xr netintro 4 ,
.Xr watchdog 4 ,
.Xr device.hints 5 ,
.Xr ifconfig 8 ,
.Xr watchdog 8
.Sh HISTORY
The
.Nm
device was ported from
.Nx
by
.An Max Khon Aq fjoe@FreeBSD.org
and first appeared in
.Fx 4.6 .
This manual page first appeared in
.Fx 5.3 .
.Sh AUTHORS
This manual page was written by
.An Tom Rhodes Aq trhodes@FreeBSD.org .
The
.Sx IMPLEMENTATION NOTES
section was submitted by
.An Max Khon Aq fjoe@FreeBSD.org
and originated from
.Nx .
.Sh BUGS
The
.Nm
driver code could do with a bit of improvement,
it would be nice if some one could come along and take care of this.
.Pp
The
.Sx IMPLEMENTATION NOTES
section is specific to all Arcnet
devices (see
.Pa sys/net/if_arcsubr.c )
and should be moved to a more generic location.