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.Dd May 27, 2020
.Dt INTRO 4 evbarm
.Os
.Sh NAME
.Nm intro
.Nd introduction to evbarm special files and hardware support
.Sh DESCRIPTION
The evbarm port is really a collection of ports of
.Nx
to a range of development and evaluation boards based on the ARM Architecture.
.Pp
This section describes the supported boards, the special files,
related driver functions, and networking support available in each system.
In this part of the manual, the
.Tn SYNOPSIS
section of
each configurable device gives a sample specification
for use in constructing a system description for the
.Xr config 1
program.
The
.Tn DIAGNOSTICS
section lists messages which may appear on the console
and/or in the system error log
.Pa /var/log/messages
due to errors in device operation;
see
.Xr syslogd 8
for more information.
.Pp
This section contains both devices
which may be configured into the system
and network related information.
The networking support is introduced in
.Xr netintro 4 .
.Sh DEVICE SUPPORT
This section describes some of the hardware supported on the various boards.
Software support for these devices comes in two forms.
A hardware
device may be supported with a character or block
.Em device driver ,
or it may be used within the networking subsystem and have a
.Em network interface driver .
Block and character devices are accessed through files in the file
system of a special type; see
.Xr mknod 8 .
Network interfaces are indirectly accessed through the interprocess
communication facilities provided by the system; see
.Xr socket 2 .
.Pp
A hardware device is identified to the system at configuration time
and the appropriate device or network interface driver is then compiled
into the system.
When the resultant system is booted, the
autoconfiguration facilities in the system probe for the device
and, if found, enable the software support for it.
If a device does not respond at autoconfiguration
time it is not accessible at any time afterwards.
To enable a device which did not autoconfigure,
the system must be rebooted.
.Pp
The autoconfiguration system is described in
.Xr autoconf 4 .
.Sh SEE ALSO
.Xr config 1 ,
.Xr autoconf 4
.Sh HISTORY
The
.Tn evbarm
.Nm intro
appeared in
.Nx 2.0 .