DMIDECODE(8)             (January 2019)              DMIDECODE(8)

          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 compo-
          nents, 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 cur-
          rently 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

          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:

          +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

          +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

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            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.

          -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 refer-
               ences 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-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 mean-
               ingful 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.

               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

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               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.

          -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 hex-
               adecimal instead.  Note that this is still a text out-
               put, 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

              --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 gener-
               ated using --dump-bin.

               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 deter-
          mine 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 sup-
          ported by the tool yet, it will print out relevant message
          in addition to requested data on the very top of the output.

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          Thus informs the output data is not reliable.

          The SMBIOS specification defines the following DMI types: r
          l __ r l.  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    Sys-
          tem Slots 10   On Board Devices 11   OEM Strings 12   System
          Configuration Options 13   BIOS Language 14   Group Associa-
          tions 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   Temper-
          ature 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   Manage-
          ment 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:

          l l __ l l.  Keyword   Types bios 0, 13 system    1, 12, 15,
          23, 32 baseboard 2, 10, 41 chassis   3 processor 4 mem-
          ory    5, 6, 16, 17 cache     7 connector 8 slot 9

          Keywords are matched case-insensitively. The following com-
          mand lines are equivalent:

          +o dmidecode --type 0 --type 13

          +o dmidecode --type 0,13

          +o dmidecode --type bios

          +o dmidecode --type BIOS

          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.

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            It is crafted to hard-code the table address at offset

          +o The DMI table is located at offset 0x20.

          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 spec-
          ification version 2.6 (and later) explicitly 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 specifica-
          tion, 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 interpret
          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.

          /sys/firmware/dmi/tables/smbios_entry_point (Linux only)
          /sys/firmware/dmi/tables/DMI (Linux only)

          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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