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man page(1) manual page
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dmidecode - DMI table decoder
dmidecode [OPTIONS]
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:
· 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.
-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. Mutually
exclusive with --dump.
- -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, systemproduct-name,
system-version, system-serial-number, baseboardmanufacturer,
baseboard-product-name, baseboard-version, baseboard-serial-number,
baseboard-asset-tag, chassis-manufacturer,
chassis-version, chassis-serial-number, chassis-asset-tag, processor-manufacturer,
processor-version. 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-version 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, and implies --quiet.
Mutually exclusive with --type and --dump.
- -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. Mutually exclusive with --string.
- -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. Mutually exclusive with --quiet and
--string.
- -h, --help
-
Display usage information and exit
- -V, --version
-
Display the version and exit
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
Additionally, type 126 is used for disabled entries, type 127 is an
end-of-table marker, and types 128 to 255 are for OEM-specific data.
dmidecode will display these entries by default, but cannot decode
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
- 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
/dev/mem
More often than not, information contained in the DMI tables is inaccurate,
incomplete or simply wrong.
Alan Cox, Jean Delvare
biosdecode(8)
, mem(4)
, ownership(8)
, vpddecode(8)
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