config root man

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.\" Copyright (c) 2004 Jason L. Wright (jason@thought.net)
.\" Copyright (c) 2005 Marius Strobl <marius@FreeBSD.org>
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.\"	from: OpenBSD: clock.4,v 1.3 2004/09/24 07:04:15 miod Exp
.\" $FreeBSD: release/9.1.0/share/man/man4/man4.sparc64/rtc.4 147531 2005-06-22 15:35:14Z ru $
.\"
.Dd June 18, 2005
.Dt RTC 4 sparc64
.Os
.Sh NAME
.Nm rtc
.Nd "non-volatile RAM / real time clock"
.Sh SYNOPSIS
.Cd "device genclock"
.Cd "device mc146818"
.Cd "device rtc"
.Sh DESCRIPTION
The
.Nm
driver is a front-end for the machine-independent
.Tn Motorola
MC146818 and compatible clocks driver.
The
.Tn Motorola
MC146818 and compatible clocks driver provides access to the real time clock
part of the chips it supports to
.Fx
by interfacing with the generic clock code.
.Pp
.Tn Dallas /
.Tn Maxim Semiconductor
DS1287 chips
(those are compatible to the
.Tn Motorola
MC146818 clocks)
are found on the ISA bus of
.Tn UltraSPARC II
systems and the EBus bus of
.Tn UltraSPARC III
systems.
.Sh DIAGNOSTICS
The following driver specific error message may be reported:
.Bl -diag
.It "mc146818_attach_attach: battery low"
The device signals that its battery is low and should be replaced.
The
.Nm
driver refused to attach the device in this case as the time in the real time
clock is probably invalid.
This gives the generic clock code the chance to use another device as the
system real time clock that otherwise would not have been chosen.
.El
.Sh SEE ALSO
.Xr ebus 4 ,
.Xr eeprom 4
.Sh HISTORY
The
.Nm
driver first appeared in
.Fx 5.4 .
.Sh AUTHORS
The
.Nm
driver was written by
.An "Marius Strobl" Aq marius@FreeBSD.org .