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DMIDECODE(8) DMIDECODE(8)
NAME
dmidecode - DMI table decoder
SYNOPSIS
dmidecode [OPTIONS]
DESCRIPTION
dmidecode is a tool for dumping a computer's DMI (some say SMBIOS) 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 BIOS 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.
The DMI table doesn't only describe what the system is currently made of, it also can report the possible evolutions
(such as the fastest supported CPU or the maximal amount of memory supported).
SMBIOS stands for System Management BIOS, while DMI stands for Desktop Management Interface. Both standards are tightly
related and developed by the DMTF (Desktop Management Task Force).
As you run it, dmidecode will try to locate the DMI table. If it succeeds, it will then parse this table and display a
list of records like this one:
Handle 0x0002, DMI type 2, 8 bytes. Base Board Information
Manufacturer: Intel
Product Name: C440GX+
Version: 727281-001
Serial Number: INCY92700942
Each record has:
o 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.
o A type. The SMBIOS 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 "Base Board Information".
o 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.
o 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.
OPTIONS
-d, --dev-mem FILE
Read memory from device FILE (default: /dev/mem)
-q, --quiet
Be less verbose. Unknown, inactive and OEM-specific entries are not displayed. Meta-data and handle references are
hidden.
-s, --string KEYWORD
Only display the value of the DMI string identified by KEYWORD. KEYWORD must be a keyword from the following
list: bios-vendor, bios-version, bios-release-date, system-manufacturer, system-product-name, system-version, sys-
tem-serial-number, system-uuid, baseboard-manufacturer, baseboard-product-name, baseboard-version, baseboard-
serial-number, baseboard-asset-tag, chassis-manufacturer, chassis-type, chassis-version, chassis-serial-number,
chassis-asset-tag, processor-family, processor-manufacturer, processor-version, processor-frequency. Each keyword
corresponds to a given DMI 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. processor-ver-
sion on a multi-processor system). If KEYWORD is not provided or not valid, a list of all valid keywords is
printed and dmidecode exits with an error. This option cannot be used more than once.
-t, --type TYPE
Only display the entries of type TYPE. TYPE can be either a DMI type number, or a comma-separated list of type
numbers, or a keyword from the following list: bios, system, baseboard, chassis, processor, memory, cache, connec-
tor, slot. 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 TYPE is not provided or not valid, a list of all
valid keywords is printed and dmidecode exits with an error.
-u, --dump
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
ASCII. This option is mainly useful for debugging.
--dump-bin FILE
Do not decode the entries, instead dump the DMI data to a file in binary form. The generated file is suitable to
pass to --from-dump later.
--from-dump FILE
Read the DMI data from a binary file previously generated using --dump-bin.
-h, --help
Display usage information and exit
-V, --version
Display the version and exit
Options --string, --type and --dump-bin determine the output format and are mutually exclusive.
DMI TYPES
The SMBIOS specification defines the following DMI types:
Type Information
----------------------------------------
0 BIOS
1 System
2 Base Board
3 Chassis
4 Processor
5 Memory Controller
6 Memory Module
7 Cache
8 Port Connector
9 System Slots
10 On Board Devices
11 OEM Strings
12 System Configuration Options
13 BIOS Language
14 Group Associations
15 System Event Log
16 Physical Memory Array
17 Memory Device
18 32-bit Memory Error
19 Memory Array Mapped Address
20 Memory Device Mapped Address
21 Built-in Pointing Device
22 Portable Battery
23 System Reset
24 Hardware Security
25 System Power Controls
26 Voltage Probe
27 Cooling Device
28 Temperature Probe
29 Electrical Current Probe
30 Out-of-band Remote Access
31 Boot Integrity Services
32 System Boot
33 64-bit Memory Error
34 Management Device
35 Management Device Component
36 Management Device Threshold Data
37 Memory Channel
38 IPMI Device
39 Power Supply
40 Additional Information
41 Onboard Device
Additionally, type 126 is used for disabled entries and type 127 is an end-of-table marker. Types 128 to 255 are for OEM-
specific data. dmidecode will display these entries by default, but it can only decode them when the vendors have con-
tributed documentation or code for them.
Keywords can be used instead of type numbers with --type. Each keyword is equivalent to a list of type numbers:
Keyword Types
------------------------------
bios 0, 13
system 1, 12, 15, 23, 32
baseboard 2, 10, 41
chassis 3
processor 4
memory 5, 6, 16, 17
cache 7
connector 8
slot 9
Keywords are matched case-insensitively. The following command lines are equivalent:
o dmidecode --type 0 --type 13
o dmidecode --type 0,13
o dmidecode --type bios
o dmidecode --type BIOS
BINARY DUMP FILE FORMAT
The binary dump files generated by --dump-bin and read using --from-dump are formatted as follows:
o The SMBIOS or DMI entry point is located at offset 0x00. It is crafted to hard-code the table address at offset 0x20.
o The DMI table is located at offset 0x20.
FILES
/dev/mem
BUGS
More often than not, information contained in the DMI tables is inaccurate, incomplete or simply wrong.
AUTHORS
Alan Cox, Jean Delvare
SEE ALSO
biosdecode(8), mem(4), ownership(8), vpddecode(8)
dmidecode November 2008 DMIDECODE(8)
