DMI table decoder
see also :
biosdecode - ownership - vpddecode
add an example, a script, a trick and tips
depends 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.
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
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:
DMI type 2, 8 bytes. Base Board Information
Product Name: C440GX+
Serial Number: INCY92700942
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
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
Read memory from device
FILE (default: /dev/mem)
Be less verbose. Unknown,
inactive and OEM -specific entries are not
displayed. Meta-data and handle references are
Only display the value of the
DMI string identified by KEYWORD.
KEYWORD must be a keyword from the following list:
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.
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
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.
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.
Do not decode the entries,
instead dump the DMI data to a file in binary form. The
generated file is suitable to pass to
Read the DMI data from a binary
file previously generated using
Display usage information and
Display the version and
--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.
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.
The SMBIOS specification defines the following
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:
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
More often than
not, information contained in the DMI tables
is inaccurate, incomplete or simply wrong.
mem, ownership , vpddecode
Alan Cox, Jean