1.\" 2.\"Copyright (c) 2010 iXsystems, Inc. 3.\"All rights reserved. 4.\" written by: Xin LI <delphij@FreeBSD.org> 5.\" 6.\"Redistribution and use in source and binary forms, with or without 7.\"modification, are permitted provided that the following conditions 8.\"are met: 9.\"1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\"2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 15.\"THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 16.\"ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17.\"IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18.\"ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 19.\"FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20.\"DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 21.\"OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22.\"HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23.\"LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24.\"OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25.\"SUCH DAMAGE. 26.\" 27.\" $FreeBSD$ 28.\" 29.Dd February 8, 2010 30.Dt NVRAM 4 31.Os 32.Sh NAME 33.Nm nvram 34.Nd "non-volatile RAM" 35.Sh SYNOPSIS 36To compile this driver into the kernel, 37place the following line in your 38kernel configuration file: 39.Bd -ragged -offset indent 40.Cd "device nvram" 41.Ed 42.Pp 43Alternatively, to load the driver as a 44module at boot time, place the following line in 45.Xr loader.conf 5 : 46.Bd -literal -offset indent 47nvram_load="YES" 48.Ed 49.Sh DESCRIPTION 50The 51.Nm 52driver provides access to BIOS configuration NVRAM on i386 and amd64 53systems. 54.Pp 55PC motherboard uses a small non-volatile memory to store BIOS settings 56which is usually part of its clock chip and sometimes referred as 57.Dq CMOS SRAM . 58This driver exposes bytes 14 through 128 of the NVRAM, or a total of 59114 bytes, at offset zero of the device file 60.Pa /dev/nvram . 61.Pp 62This driver is useful for cloning machines that shares the same hardware 63configuration and need same BIOS setting tweaks. 64.Sh IMPLEMENTATION NOTES 65The BIOS NVRAM's bytes 16 through 31 are checksummed at byte 32. 66This driver 67.Em does not 68take care for these checksums. 69.Sh EXAMPLES 70Backup existing BIOS NVRAM to 71.Pa nvram.bin : 72.Pp 73.Dl dd if=/dev/nvram of=nvram.bin 74.Pp 75Restore BIOS NVRAM from 76.Pa nvram.bin : 77.Pp 78.Dl dd if=nvram.bin of=/dev/nvram 79.Sh SEE ALSO 80.Xr dd 1 81.Sh HISTORY 82The 83.Nm 84device driver first appeared in 85.Fx 6.4 . 86.Sh AUTHORS 87.An -nosplit 88The 89.Nm 90device driver was written by 91.An Peter Wemm . 92This manual page was written by 93.An Xin LI . 94