94 lines
2.8 KiB
Groff
94 lines
2.8 KiB
Groff
.\"
|
|
.\"Copyright (c) 2010 iXsystems, Inc.
|
|
.\"All rights reserved.
|
|
.\" written by: Xin LI <delphij@FreeBSD.org>
|
|
.\"
|
|
.\"Redistribution and use in source and binary forms, with or without
|
|
.\"modification, are permitted provided that the following conditions
|
|
.\"are met:
|
|
.\"1. Redistributions of source code must retain the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer.
|
|
.\"2. Redistributions in binary form must reproduce the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
|
.\" documentation and/or other materials provided with the distribution.
|
|
.\"
|
|
.\"THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
|
|
.\"ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
.\"IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
.\"ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
|
|
.\"FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
.\"DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
.\"OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
.\"HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
.\"LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
.\"OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
.\"SUCH DAMAGE.
|
|
.\"
|
|
.\" $FreeBSD$
|
|
.\"
|
|
.Dd February 8, 2010
|
|
.Dt NVRAM 4
|
|
.Os
|
|
.Sh NAME
|
|
.Nm nvram
|
|
.Nd "non-volatile RAM"
|
|
.Sh SYNOPSIS
|
|
To compile this driver into the kernel,
|
|
place the following line in your
|
|
kernel configuration file:
|
|
.Bd -ragged -offset indent
|
|
.Cd "device nvram"
|
|
.Ed
|
|
.Pp
|
|
Alternatively, to load the driver as a
|
|
module at boot time, place the following line in
|
|
.Xr loader.conf 5 :
|
|
.Bd -literal -offset indent
|
|
nvram_load="YES"
|
|
.Ed
|
|
.Sh DESCRIPTION
|
|
The
|
|
.Nm
|
|
driver provides access to BIOS configuration NVRAM on i386 and amd64
|
|
systems.
|
|
.Pp
|
|
PC motherboard uses a small non-volatile memory to store BIOS settings
|
|
which is usually part of its clock chip and sometimes referred as
|
|
.Dq CMOS SRAM .
|
|
This driver exposes bytes 14 through 128 of the NVRAM, or a total of
|
|
114 bytes, at offset zero of the device file
|
|
.Pa /dev/nvram .
|
|
.Pp
|
|
This driver is useful for cloning machines that shares the same hardware
|
|
configuration and need same BIOS setting tweaks.
|
|
.Sh IMPLEMENTATION NOTES
|
|
The BIOS NVRAM's bytes 16 through 31 are checksummed at byte 32.
|
|
This driver
|
|
.Em does not
|
|
take care for these checksums.
|
|
.Sh EXAMPLES
|
|
Backup existing BIOS NVRAM to
|
|
.Pa nvram.bin :
|
|
.Pp
|
|
.Dl dd if=/dev/nvram of=nvram.bin
|
|
.Pp
|
|
Restore BIOS NVRAM from
|
|
.Pa nvram.bin :
|
|
.Pp
|
|
.Dl dd if=nvram.bin of=/dev/nvram
|
|
.Sh SEE ALSO
|
|
.Xr dd 1
|
|
.Sh HISTORY
|
|
The
|
|
.Nm
|
|
device driver first appeared in
|
|
.Fx 6.4 .
|
|
.Sh AUTHORS
|
|
.An -nosplit
|
|
The
|
|
.Nm
|
|
device driver was written by
|
|
.An Peter Wemm .
|
|
This manual page was written by
|
|
.An Xin LI .
|