from the man command:
Reformatting dmidecode(8), please wait... DMIDECODE(8) DMIDECODE(8)
dmidecode - DMI table decoder
Note: In vSphere 5.x this command no longer exists and you have to use
dmidecode is a tool for dumping a computerâs DMI (some say SMBIOS) table contents in a human-readable format. This table contains a description of the systemâs 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 doesnât 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 boardâs 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. Mutuâ ally 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, system- product-name, system-version, system-serial-number, baseboard- manufacturer, baseboard-product-name, baseboard-version, baseâ board-serial-number, baseboard-asset-tag, chassis-manufacturer, chassis-version, chassis-serial-number, chassis-asset-tag, proâ cessor-manufacturer, processor-version. Each keyword correâ sponds 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, chasâ sis, 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 0 --type 13
- dmidecode --type 0,13
- dmidecode --type bios
- dmidecode --type BIOS
More often than not, information contained in the DMI tables is inaccuâ rate, incomplete or simply wrong.
Alan Cox, Jean Delvare
biosdecode(8), mem(4), ownership(8), vpddecode(8)
dmidecode August 2005 DMIDECODE(8)
Here's a snippet of output on an ESX host when displaying memory info:
Handle 0x0028 DMI type 17, 27 bytes. Memory Device Array Handle: 0x0025 Error Information Handle: No Error Total Width: 76 bits Data Width: 72 bits Size: 1024 MB Form Factor: DIMM Set: 1 Locator: DIMM 2A Bank Locator: Bank0 Bank1 Type: DDR Type Detail: Synchronous Speed: 266 MHz (3.8 ns) Manufacturer: Not Specified Serial Number: Not Specified Asset Tag: Not Specified Part Number: Not Specified