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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 hard‐
       ware.   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. 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 Infor‐
         mation".

       • 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 following list: bios-vendor, bios-version, bios-release-date, bios-
              revision, firmware-revision, system-manufacturer, system-product-name, system-version,
              system-serial-number,  system-uuid,  system-sku-number, system-family, baseboard-manu‐‐
              facturer, baseboard-product-name,  baseboard-version,  baseboard-serial-number,  base‐‐
              board-asset-tag,  chassis-manufacturer, chassis-type, chassis-version, chassis-serial-
              number, chassis-asset-tag,  processor-family,  processor-manufacturer,  processor-ver‐‐
              sion,  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.  pro‐‐
              cessor-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 op‐
              tion cannot be used more than once.

              Note: on Linux, most of these strings can alternatively be read directly  from  sysfs,
              typically  from files under /sys/devices/virtual/dmi/id.  Most of these files are even
              readable by regular users.

       -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, sys‐‐
              tem, 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 er‐
              ror.

       -H, --handle HANDLE
              Only display the entry whose handle matches HANDLE.  HANDLE is a 16-bit integer.

       -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  use‐
              ful 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.

           --oem-string N
              Only display the value of the OEM string number N. The first OEM string has number  1.
              With special value "count", return the number of OEM strings instead.

       -h, --help
              Display usage information and exit

       -V, --version
              Display the version and exit

       Options --string, --type, --dump-bin and --oem-string determine the output format and are mu‐
       tually exclusive.

       Please note in case of dmidecode is run on a system with BIOS that boasts new SMBIOS specifi‐
       cation,  which  is not supported by the tool yet, it will print out relevant message in addi‐
       tion to requested data on the very top of the output. Thus informs the output data is not re‐
       liable.

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
         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 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 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:

       • 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:

       • The  SMBIOS  or  DMI entry point is located at offset 0x00.  It is crafted to hard-code the
         table address at offset 0x20.

       • The DMI table is located at offset 0x20.

UUID FORMAT
       There is some ambiguity about how to interpret the UUID fields prior to SMBIOS  specification
       version  2.6.  There was no mention of byte swapping, and RFC 4122 says that no byte swapping
       should be applied by default. However, SMBIOS specification version 2.6 (and  later)  explic‐
       itly  states  that  the  first  3  fields of the UUID should be read as little-endian numbers
       (byte-swapped).  Furthermore, it implies that the same was already true for older versions of
       the  specification, even though it was not mentioned. In practice, many hardware vendors were
       not byte-swapping the UUID. So, in order to preserve compatibility, it was decided to  inter‐
       pret  the  UUID  fields  according  to RFC 4122 (no byte swapping) when the SMBIOS version is
       older than 2.6, and to interpret the first 3 fields as little-endian (byte-swapped) when  the
       SMBIOS version is 2.6 or later. The Linux kernel follows the same logic.

FILES
       /dev/mem
       /sys/firmware/dmi/tables/smbios_entry_point (Linux only)
       /sys/firmware/dmi/tables/DMI (Linux only)

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                                   January 2019                                DMIDECODE(8)