DMIDECODE(8) System Manager's Manual 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 evo‐
lutions (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. It will first try to read the DMI table from sysfs,
and next try reading directly from memory if sysfs access failed. If dmidecode succeeds in locating a valid
DMI table, 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:
· 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.
· 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".
· 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.
· 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
-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, connector, 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.
--no-sysfs
Do not attempt to read DMI data from sysfs files. This is mainly useful for debugging.
-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.
Please note in case of dmidecode 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.
DMI TYPES
The SMBIOS specification defines the following DMI types:
Type Information
────────────────────────────────────────────
0 BIOS
1 System
2 Baseboard
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
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 Devices Extended Information
42 Management Controller Host Interface
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 contributed documentation or code for them.
Keywords can be used instead of type numbers with --type. Each keyword is equivalent to a list of type num‐
bers:
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:
· dmidecode --type 0 --type 13
· dmidecode --type 0,13
· dmidecode --type bios
· dmidecode --type BIOS
BINARY DUMP FILE FORMAT
The binary dump files generated by --dump-bin and read using --from-dump are formatted as follows:
AUTHORS
Alan Cox, Jean Delvare
SEE ALSO
biosdecode(8), mem(4), ownership(8), vpddecode(8)
dmidecode March 2012 DMIDECODE(8)
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