251 lines
7.3 KiB
Groff
251 lines
7.3 KiB
Groff
.\"***************************************************************************\
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.\" nvramtool.8
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.\"***************************************************************************
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.\" Copyright (C) 2002, 2003 The Regents of the University of California.
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.\" Produced at the Lawrence Livermore National Laboratory.
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.\" Written by David S. Peterson <dsp@llnl.gov> <dave_peterson@pobox.com>.
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.\" UCRL-CODE-2003-012
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.\" All rights reserved.
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.\"
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.\" This file is part of nvramtool, a utility for reading/writing coreboot
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.\" parameters and displaying information from the coreboot table.
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.\" For details, see https://www.coreboot.org/nvramtool.
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.\"
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.\" Please also read the file DISCLAIMER which is included in this software
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.\" distribution.
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.\"
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.\" This program is free software; you can redistribute it and/or modify it
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.\" under the terms of the GNU General Public License (as published by the
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.\" Free Software Foundation) version 2, dated June 1991.
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.\"
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.\" This program is distributed in the hope that it will be useful, but
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.\" WITHOUT ANY WARRANTY; without even the IMPLIED WARRANTY OF
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.\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the terms and
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.\" conditions of the GNU General Public License for more details.
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.\"***************************************************************************/
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.TH NVRAMTOOL 8 "September 2008"
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.SH NAME
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nvramtool \- read/write coreboot-related information
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.SH SYNOPSIS
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.B "nvramtool [OPTS] [-n] -r NAME"
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.br
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.B "nvramtool [OPTS] -e NAME"
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.br
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.B "nvramtool [OPTS] -a"
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.br
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.B "nvramtool [OPTS] -w NAME=VALUE"
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.br
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.B "nvramtool [OPTS] -p INPUT_FILE"
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.br
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.B "nvramtool [OPTS] -i"
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.br
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.B "nvramtool [OPTS] -c [VALUE]"
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.br
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.B "nvramtool [OPTS] -l [ARG]"
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.br
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.B "nvramtool [OPTS] -d"
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.br
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.B "nvramtool [OPTS] -Y"
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.br
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.B "nvramtool [OPTS] -b OUTPUT_FILE"
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.br
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.B "nvramtool [OPTS] -B INPUT_FILE"
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.br
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.B "nvramtool [OPTS] -x"
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.br
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.B "nvramtool [OPTS] -X DUMPFILE"
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.br
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.B "nvramtool [OPTS] -v"
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.br
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.B "nvramtool [OPTS] -h"
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.SH DESCRIPTION
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.B "nvramtool"
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is a utility for reading/writing coreboot parameters and displaying
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information from the coreboot table.
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The coreboot table resides in low physical memory. It is created at boot
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time by coreboot, and contains various system information such as the type
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of mainboard in use. It specifies locations in the CMOS (nonvolatile RAM)
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where the coreboot parameters are stored.
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This program is intended for (x86-based) systems that use coreboot. For
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information about coreboot, see
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.br
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https://www.coreboot.org/.
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.SH PARAMETERS
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.TP
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.B "[-n] -r NAME"
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Show the value of the coreboot parameter given by
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.B "NAME."
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If
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.B "-n"
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is specified, show only the value. Otherwise show both parameter name and
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value.
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.TP
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.B "-e NAME"
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Show all possible values for parameter given by
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.B "NAME."
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.TP
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.B "-a"
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Show the names and values for all coreboot parameters.
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.TP
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.B "-w NAME=VALUE"
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Assign
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.B "VALUE"
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to coreboot parameter given by
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.B "NAME."
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.TP
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.B "-p INPUT_FILE"
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Assign values to coreboot parameters according to the contents of
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.B "INPUT_FILE."
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The format of this file is described below.
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.TP
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.B "-i"
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This is similar to the
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.B "-p"
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option, except that the contents of the input file are taken from standard
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input.
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.TP
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.B "-c [VALUE]"
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If
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.B "VALUE"
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is present then set the CMOS checksum for the coreboot parameters to
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.B "VALUE."
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Otherwise, show the checksum value.
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.TP
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.B "-l [ARG]"
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If
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.B "ARG"
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is present then show information from the coreboot table as specified by
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.B "ARG."
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Otherwise show all possible values for
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.B "ARG."
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.TP
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.B "-d"
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Do a low-level dump of the coreboot table.
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.TP
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.B "-Y"
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Write CMOS layout information to standard output. If redirected to a file,
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the layout information may be used as input for the
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.B "'-y LAYOUT_FILE'"
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option (see below).
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.TP
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.B "-b OUTPUT_FILE"
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Write the contents of CMOS memory to the binary file
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.B "OUTPUT_FILE."
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The first 14 bytes of
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.B "OUTPUT_FILE"
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do not contain actual CMOS data, and are always written as zeros. This is
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because the first 14 bytes of the CMOS area do not contain CMOS memory. These
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bytes are involved with the functioning of the real time clock.
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.TP
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.B "-B INPUT_FILE"
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Read binary data from
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.B "INPUT_FILE"
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and write the data to CMOS memory. The first 14 bytes of
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.B "INPUT_FILE"
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are skipped and data is written to CMOS starting at the 15th byte of the CMOS
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area. This is because the first 14 bytes of the CMOS area do not contain CMOS
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memory. These bytes are involved with the functioning of the real time clock.
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.TP
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.B "-x"
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Show a hex dump of all CMOS data. The first 14 bytes of the dump do not
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contain actual CMOS data, and are always shown as zeros. This is because the
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first 14 bytes of the CMOS area do not contain CMOS memory. These bytes are
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involved with the functioning of the real time clock.
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.TP
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.B "-X DUMPFILE"
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Read binary data from
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.B "DUMPFILE"
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(presumably a CMOS dumpfile created using the
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.B "-b OUTPUT_FILE"
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option) and show a hex dump of the data.
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.TP
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.B "-v"
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Show version information for this program.
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.TP
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.B "-h"
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Show a help message for this program.
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.SH "OPTIONS"
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In all cases above,
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.B "[OPTS]"
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evaluates to the following:
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.B " [-y LAYOUT_FILE | -t]"
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The
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.B "'-y LAYOUT_FILE'"
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option tells nvramtool to obtain CMOS layout information from the contents of
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.B "LAYOUT_FILE."
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Likewise, the
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.B "'-t'"
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option tells nvramtool to obtain CMOS layout information from the CMOS option
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table (contained within the coreboot table). If neither option is
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specified, the CMOS option table is used by default.
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.B "LAYOUT_FILE"
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follows the format of the
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.B "cmos.layout"
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files provided by coreboot.
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If the coreboot installed on your system was built without specifying
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.B "CONFIG_HAVE_OPTION_TABLE,"
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then the coreboot table will not contain a CMOS option table. In this case,
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the
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.B "'-y LAYOUT_FILE'"
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option must be used.
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These two options are silently ignored when used in combination with other
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options (such as
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.B "-h,"
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for instance) for which they are not applicable.
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.SH FILE FORMAT
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For the
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.B "-p"
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option,
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.B "INPUT_FILE"
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must consist of a sequence of lines such that each line is either a blank
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line, a comment, or an assignment. A blank line consists only of zero or
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more whitespace characters (spaces and tabs). A comment is constructed as
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follows:
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.B " [ws]#[text]"
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Here,
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.B "[ws]"
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indicates optional whitespace characters and
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.B "[text]"
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indicates optional text. Blank lines and comments are both ignored. An
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assignment is constructed as follows:
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.B " [ws]NAME[ws]=[ws]VALUE[ws]"
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Here,
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.B "NAME"
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is the name of a coreboot parameter and
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.B "VALUE"
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is the value that will be assigned to
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.B "NAME."
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.B "VALUE"
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is allowed to contain whitespace characters, but it must begin and end with
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nonwhitespace characters. Note that each comment must appear on a line by
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itself. If you attempt to add a comment to the end of an assignment, then the
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comment will be interpreted as part of
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.B "VALUE."
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It is useful to observe that the output produced by both the
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.B "-a"
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and the
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.B "'[-n] NAME'"
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options (without
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.B "-n"
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specified) adheres to this file format.
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.SH BUGS
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This program does not implement any type of synchronization to ensure that
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different processes don't stomp on each other when trying to access the
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nonvolatile RAM simultaneously. Therefore, corruption of the BIOS parameter
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values may occur if multiple instances of this program are executed
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concurrently.
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.SH AUTHORS
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David S. Peterson <dsp@llnl.gov> <dave_peterson@pobox.com>
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.br
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Stefan Reinauer <stepan@coresystems.de>
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