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<H1>DMIDECODE</H1>
Section: Maintenance Commands (8)<BR>Updated: March 2012<BR><A HREF="#index">Index</A>
<A HREF="/cgi-bin/man/man2html">Return to Main Contents</A><HR>
<A NAME="lbAB">&nbsp;</A>
<H2>NAME</H2>
dmidecode - <FONT SIZE="-1">DMI</FONT> table decoder
<A NAME="lbAC">&nbsp;</A>
<H2>SYNOPSIS</H2>
<B>dmidecode</B>
[<B>OPTIONS</B>]
<P>
<A NAME="lbAD">&nbsp;</A>
<H2>DESCRIPTION</H2>
<B>dmidecode</B>
is a tool for dumping a computer's <FONT SIZE="-1">DMI</FONT> (some say <FONT SIZE="-1">SMBIOS</FONT>) table
contents in a human-readable format. This table contains a description of the
system's hardware components, as well as other useful pieces of information
such as serial numbers and <FONT SIZE="-1">BIOS</FONT> revision. Thanks to this table, you can
retrieve this information without having to probe for the actual hardware.
While this is a good point in terms of report speed and safeness, this also
makes the presented information possibly unreliable.
<P>
The <FONT SIZE="-1">DMI</FONT> table doesn't only describe what the system is currently made
of, it also can report the possible evolutions (such as the fastest supported
<FONT SIZE="-1">CPU</FONT> or the maximal amount of memory supported).
<P>
<FONT SIZE="-1">SMBIOS</FONT> stands for System Management <FONT SIZE="-1">BIOS</FONT>, while <FONT SIZE="-1">DMI</FONT>
stands for Desktop Management Interface. Both standards are tightly related
and developed by the <FONT SIZE="-1">DMTF</FONT> (Desktop Management Task Force).
<P>
As you run it,
<B>dmidecode</B>
will try to locate the <FONT SIZE="-1">DMI</FONT> table. It will first try to read the DMI table
from sysfs, and next try reading directly from memory if sysfs access failed.
If
<B>dmidecode</B>
succeeds in locating a valid DMI table, it will then parse this table
and display a list of records like this one:
<P>
Handle 0x0002, DMI type 2, 8 bytes.
Base Board Information
<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Manufacturer:&nbsp;Intel
<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Product&nbsp;Name:&nbsp;C440GX+
<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Version:&nbsp;727281-001
<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Serial&nbsp;Number:&nbsp;INCY92700942
<P>
Each record has:
<DL COMPACT>
<DT id="1">&bull;<DD>
A handle. This is a unique identifier, which allows records to
reference each other. For example, processor records usually reference
cache memory records using their handles.
<DT id="2">&bull;<DD>
A type. The <FONT SIZE="-1">SMBIOS</FONT> specification defines different types of elements
a computer can be made of. In this example, the type is 2, which
means that the record contains &quot;Base Board Information&quot;.
<DT id="3">&bull;<DD>
A size. Each record has a 4-byte header (2 for the handle, 1 for the type,
1 for the size), the rest is used by the record data. This value doesn't
take text strings into account (these are placed at the end of the record),
so the actual length of the record may be (and is often) greater than the
displayed value.
<DT id="4">&bull;<DD>
Decoded values. The information presented of course depends on the type
of record. Here, we learn about the board's manufacturer, model, version
and serial number.
<P>
</DL>
<A NAME="lbAE">&nbsp;</A>
<H2>OPTIONS</H2>
<DL COMPACT>
<DT id="5"><B>-d</B>, <B>--dev-mem FILE</B>
<DD>
Read memory from device <B>FILE</B> (default: <B>/dev/mem</B>)
<DT id="6"><B>-q</B>, <B>--quiet</B>
<DD>
Be less verbose. Unknown, inactive and <FONT SIZE="-1">OEM</FONT>-specific entries are not
displayed. Meta-data and handle references are hidden.
<DT id="7"><B>-s</B>, <B>--string KEYWORD</B>
<DD>
Only display the value of the <FONT SIZE="-1">DMI</FONT> string identified by <B>KEYWORD</B>.
<B>KEYWORD</B> must be a keyword from the following list: <B>bios-vendor</B>,
<B>bios-version</B>, <B>bios-release-date</B>,
<B>system-manufacturer</B>, <B>system-product-name</B>,
<B>system-version</B>, <B>system-serial-number</B>,
<B>system-uuid</B>, <B>system-family</B>,
<B>baseboard-manufacturer</B>, <B>baseboard-product-name</B>,
<B>baseboard-version</B>, <B>baseboard-serial-number</B>,
<B>baseboard-asset-tag</B>, <B>chassis-manufacturer</B>,
<B>chassis-type</B>,
<B>chassis-version</B>, <B>chassis-serial-number</B>,
<B>chassis-asset-tag</B>, <B>processor-family</B>,
<B>processor-manufacturer</B>,
<B>processor-version</B>, <B>processor-frequency</B>.
Each keyword corresponds to a given <FONT SIZE="-1">DMI</FONT> type and a given offset
within this entry type.
Not all strings may be meaningful or even defined on all systems. Some
keywords may return more than one result on some systems (e.g.
<B>processor-version</B> on a multi-processor system).
If <B>KEYWORD</B> is not provided or not valid, a list of all valid
keywords is printed and
<B>dmidecode</B>
exits with an error.
This option cannot be used more than once.
<P>
Note: on Linux, most of these strings can alternatively be read directly
from
<B>sysfs</B>,
typically from files under
<I>/sys/devices/virtual/dmi/id</I>.
Most of these files are even readable by regular users.
<DT id="8"><B>-t</B>, <B>--type TYPE</B>
<DD>
Only display the entries of type <B>TYPE</B>. <B>TYPE</B> can be either a
<FONT SIZE="-1">DMI</FONT> type number, or a comma-separated list of type numbers, or a
keyword from the following list: <B>bios</B>, <B>system</B>,
<B>baseboard</B>, <B>chassis</B>, <B>processor</B>, <B>memory</B>,
<B>cache</B>, <B>connector</B>, <B>slot</B>. Refer to the DMI TYPES section
below for details.
If this option is used more than once, the set of displayed entries will be
the union of all the given types.
If <B>TYPE</B> is not provided or not valid, a list of all valid keywords
is printed and
<B>dmidecode</B>
exits with an error.
<DT id="9"><B>-H</B>, <B>--handle HANDLE</B>
<DD>
Only display the entry whose handle matches <B>HANDLE</B>. <B>HANDLE</B>
is a 16-bit integer.
<DT id="10"><B>-u</B>, <B>--dump</B>
<DD>
Do not decode the entries, dump their contents as hexadecimal instead.
Note that this is still a text output, no binary data will be thrown upon
you. The strings attached to each entry are displayed as both
hexadecimal and <FONT SIZE="-1">ASCII</FONT>. This option is mainly useful for debugging.
<DT id="11"><B> </B> <B>--dump-bin FILE</B>
<DD>
Do not decode the entries, instead dump the DMI data to a file in binary
form. The generated file is suitable to pass to <B>--from-dump</B>
later.
<DT id="12"><B> </B> <B>--from-dump FILE</B>
<DD>
Read the DMI data from a binary file previously generated using
<B>--dump-bin</B>.
<DT id="13"><B> </B> <B>--no-sysfs</B>
<DD>
Do not attempt to read DMI data from sysfs files. This is mainly useful for
debugging.
<DT id="14"><B> </B> <B>--oem-string N</B>
<DD>
Only display the value of the <FONT SIZE="-1">OEM</FONT> string number <B>N</B>. The first
<FONT SIZE="-1">OEM</FONT> string has number 1. With special value &quot;count&quot;, return the
number of OEM strings instead.
<DT id="15"><B>-h</B>, <B>--help</B>
<DD>
Display usage information and exit
<DT id="16"><B>-V</B>, <B>--version</B>
<DD>
Display the version and exit
</DL>
<P>
Options --string, --type, --dump-bin and --oem-string
determine the output format and are mutually exclusive.
<P>
Please note in case of
<B>dmidecode</B>
is run on a system with BIOS that boasts new SMBIOS specification, which
is not supported by the tool yet, it will print out relevant message in
addition to requested data on the very top of the output. Thus informs the
output data is not reliable.
<P>
<A NAME="lbAF">&nbsp;</A>
<H2>DMI TYPES</H2>
The <FONT SIZE="-1">SMBIOS</FONT> specification defines the following <FONT SIZE="-1">DMI</FONT> types:
<P>
<TABLE>
<TR VALIGN=top><TD ALIGN=right>Type</TD><TD>Information<BR></TD></TR>
<TR VALIGN=top><TD><HR></TD><TD><HR></TD></TR>
<TR VALIGN=top><TD ALIGN=right>1</TD><TD>System<BR></TD></TR>
<TR VALIGN=top><TD ALIGN=right>2</TD><TD>Baseboard<BR></TD></TR>
<TR VALIGN=top><TD ALIGN=right>3</TD><TD>Chassis<BR></TD></TR>
<TR VALIGN=top><TD ALIGN=right>4</TD><TD>Processor<BR></TD></TR>
<TR VALIGN=top><TD ALIGN=right>5</TD><TD>Memory Controller<BR></TD></TR>
<TR VALIGN=top><TD ALIGN=right>6</TD><TD>Memory Module<BR></TD></TR>
<TR VALIGN=top><TD ALIGN=right>7</TD><TD>Cache<BR></TD></TR>
<TR VALIGN=top><TD ALIGN=right>8</TD><TD>Port Connector<BR></TD></TR>
<TR VALIGN=top><TD ALIGN=right>9</TD><TD>System Slots<BR></TD></TR>
<TR VALIGN=top><TD ALIGN=right>10</TD><TD>On Board Devices<BR></TD></TR>
<TR VALIGN=top><TD ALIGN=right>11</TD><TD>OEM Strings<BR></TD></TR>
<TR VALIGN=top><TD ALIGN=right>12</TD><TD>System Configuration Options<BR></TD></TR>
<TR VALIGN=top><TD ALIGN=right>13</TD><TD>BIOS Language<BR></TD></TR>
<TR VALIGN=top><TD ALIGN=right>14</TD><TD>Group Associations<BR></TD></TR>
<TR VALIGN=top><TD ALIGN=right>15</TD><TD>System Event Log<BR></TD></TR>
<TR VALIGN=top><TD ALIGN=right>16</TD><TD>Physical Memory Array<BR></TD></TR>
<TR VALIGN=top><TD ALIGN=right>17</TD><TD>Memory Device<BR></TD></TR>
<TR VALIGN=top><TD ALIGN=right>18</TD><TD>32-bit Memory Error<BR></TD></TR>
<TR VALIGN=top><TD ALIGN=right>19</TD><TD>Memory Array Mapped Address<BR></TD></TR>
<TR VALIGN=top><TD ALIGN=right>20</TD><TD>Memory Device Mapped Address<BR></TD></TR>
<TR VALIGN=top><TD ALIGN=right>21</TD><TD>Built-in Pointing Device<BR></TD></TR>
<TR VALIGN=top><TD ALIGN=right>22</TD><TD>Portable Battery<BR></TD></TR>
<TR VALIGN=top><TD ALIGN=right>23</TD><TD>System Reset<BR></TD></TR>
<TR VALIGN=top><TD ALIGN=right>24</TD><TD>Hardware Security<BR></TD></TR>
<TR VALIGN=top><TD ALIGN=right>25</TD><TD>System Power Controls<BR></TD></TR>
<TR VALIGN=top><TD ALIGN=right>26</TD><TD>Voltage Probe<BR></TD></TR>
<TR VALIGN=top><TD ALIGN=right>27</TD><TD>Cooling Device<BR></TD></TR>
<TR VALIGN=top><TD ALIGN=right>28</TD><TD>Temperature Probe<BR></TD></TR>
<TR VALIGN=top><TD ALIGN=right>29</TD><TD>Electrical Current Probe<BR></TD></TR>
<TR VALIGN=top><TD ALIGN=right>30</TD><TD>Out-of-band Remote Access<BR></TD></TR>
<TR VALIGN=top><TD ALIGN=right>31</TD><TD>Boot Integrity Services<BR></TD></TR>
<TR VALIGN=top><TD ALIGN=right>32</TD><TD>System Boot<BR></TD></TR>
<TR VALIGN=top><TD ALIGN=right>33</TD><TD>64-bit Memory Error<BR></TD></TR>
<TR VALIGN=top><TD ALIGN=right>34</TD><TD>Management Device<BR></TD></TR>
<TR VALIGN=top><TD ALIGN=right>35</TD><TD>Management Device Component<BR></TD></TR>
<TR VALIGN=top><TD ALIGN=right>36</TD><TD>Management Device Threshold Data<BR></TD></TR>
<TR VALIGN=top><TD ALIGN=right>37</TD><TD>Memory Channel<BR></TD></TR>
<TR VALIGN=top><TD ALIGN=right>38</TD><TD>IPMI Device<BR></TD></TR>
<TR VALIGN=top><TD ALIGN=right>39</TD><TD>Power Supply<BR></TD></TR>
<TR VALIGN=top><TD ALIGN=right>40</TD><TD>Additional Information<BR></TD></TR>
<TR VALIGN=top><TD ALIGN=right>41</TD><TD>Onboard Devices Extended Information<BR></TD></TR>
<TR VALIGN=top><TD ALIGN=right>42</TD><TD>Management Controller Host Interface<BR></TD></TR>
</TABLE>
<P>
Additionally, type 126 is used for disabled entries and type 127 is an
end-of-table marker. Types 128 to 255 are for <FONT SIZE="-1">OEM</FONT>-specific data.
<B>dmidecode</B>
will display these entries by default, but it can only decode them
when the vendors have contributed documentation or code for them.
<P>
Keywords can be used instead of type numbers with <B>--type</B>.
Each keyword is equivalent to a list of type numbers:
<P>
<TABLE>
<TR VALIGN=top><TD>Keyword</TD><TD>Types<BR></TD></TR>
<TR VALIGN=top><TD><HR></TD><TD><HR></TD></TR>
<TR VALIGN=top><TD>system</TD><TD>1, 12, 15, 23, 32<BR></TD></TR>
<TR VALIGN=top><TD>baseboard</TD><TD>2, 10, 41<BR></TD></TR>
<TR VALIGN=top><TD>chassis</TD><TD>3<BR></TD></TR>
<TR VALIGN=top><TD>processor</TD><TD>4<BR></TD></TR>
<TR VALIGN=top><TD>memory</TD><TD>5, 6, 16, 17<BR></TD></TR>
<TR VALIGN=top><TD>cache</TD><TD>7<BR></TD></TR>
<TR VALIGN=top><TD>connector</TD><TD>8<BR></TD></TR>
<TR VALIGN=top><TD>slot</TD><TD>9<BR></TD></TR>
</TABLE>
<P>
Keywords are matched case-insensitively. The following command lines are equivalent:
<DL COMPACT>
<DT id="17">&bull;<DD>
dmidecode --type 0 --type 13
<DT id="18">&bull;<DD>
dmidecode --type 0,13
<DT id="19">&bull;<DD>
dmidecode --type bios
<DT id="20">&bull;<DD>
dmidecode --type BIOS
<P>
</DL>
<A NAME="lbAG">&nbsp;</A>
<H2>BINARY DUMP FILE FORMAT</H2>
The binary dump files generated by --dump-bin and read using --from-dump
are formatted as follows:
<DL COMPACT>
<DT id="21">&bull;<DD>
The SMBIOS or DMI entry point is located at offset 0x00.
It is crafted to hard-code the table address at offset 0x20.
<DT id="22">&bull;<DD>
The DMI table is located at offset 0x20.
<P>
</DL>
<A NAME="lbAH">&nbsp;</A>
<H2>FILES</H2>
<I>/dev/mem</I>
<I>/sys/firmware/dmi/tables/smbios_entry_point (Linux only)</I>
<I>/sys/firmware/dmi/tables/DMI (Linux only)</I>
<A NAME="lbAI">&nbsp;</A>
<H2>BUGS</H2>
More often than not, information contained in the <FONT SIZE="-1">DMI</FONT> tables is inaccurate,
incomplete or simply wrong.
<A NAME="lbAJ">&nbsp;</A>
<H2>AUTHORS</H2>
Alan Cox, Jean Delvare
<A NAME="lbAK">&nbsp;</A>
<H2>SEE ALSO</H2>
<B><A HREF="/cgi-bin/man/man2html?8+biosdecode">biosdecode</A></B>(8),
<B><A HREF="/cgi-bin/man/man2html?4+mem">mem</A></B>(4),
<B><A HREF="/cgi-bin/man/man2html?8+ownership">ownership</A></B>(8),
<B><A HREF="/cgi-bin/man/man2html?8+vpddecode">vpddecode</A></B>(8)
<P>
<HR>
<A NAME="index">&nbsp;</A><H2>Index</H2>
<DL>
<DT id="23"><A HREF="#lbAB">NAME</A><DD>
<DT id="24"><A HREF="#lbAC">SYNOPSIS</A><DD>
<DT id="25"><A HREF="#lbAD">DESCRIPTION</A><DD>
<DT id="26"><A HREF="#lbAE">OPTIONS</A><DD>
<DT id="27"><A HREF="#lbAF">DMI TYPES</A><DD>
<DT id="28"><A HREF="#lbAG">BINARY DUMP FILE FORMAT</A><DD>
<DT id="29"><A HREF="#lbAH">FILES</A><DD>
<DT id="30"><A HREF="#lbAI">BUGS</A><DD>
<DT id="31"><A HREF="#lbAJ">AUTHORS</A><DD>
<DT id="32"><A HREF="#lbAK">SEE ALSO</A><DD>
</DL>
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