.TH DMIDECODE 8 "January 2019" "dmidecode"

.SH NAME

dmidecode \- \s-1DMI\s0 table decoder

.SH SYNOPSIS

.B dmidecode

.RB [ OPTIONS ]

.SH DESCRIPTION

.B dmidecode

is a tool for dumping a computer's \s-1DMI\s0 (some say \s-1SMBIOS\s0) 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 \s-1BIOS\s0 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 \s-1DMI\s0 table doesn't only describe what the system is currently made

of, it also can report the possible evolutions (such as the fastest supported

\s-1CPU\s0 or the maximal amount of memory supported).

\s-1SMBIOS\s0 stands for System Management \s-1BIOS\s0, while \s-1DMI\s0

stands for Desktop Management Interface. Both standards are tightly related

and developed by the \s-1DMTF\s0 (Desktop Management Task Force).

As you run it,

.B dmidecode

will try to locate the \s-1DMI\s0 table. It will first try to read the DMI table

from sysfs, and next try reading directly from memory if sysfs access failed.

If

.B 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:

.IP \(bu "\w'\(bu'u+1n"

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.

.IP \(bu

A type. The \s-1SMBIOS\s0 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".

.IP \(bu

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.

.IP \(bu

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.

.SH OPTIONS

.TP

.BR "-d" ", " "--dev-mem FILE"

Read memory from device \fBFILE\fR (default: \fB/dev/mem\fR)

.TP

.BR "-q" ", " "--quiet"

Be less verbose. Unknown, inactive and \s-1OEM\s0-specific entries are not

displayed. Meta-data and handle references are hidden.

.TP

.BR "-s" ", " "--string KEYWORD"

Only display the value of the \s-1DMI\s0 string identified by \fBKEYWORD\fR.

\fBKEYWORD\fR must be a keyword from the following list: \fBbios-vendor\fR,

\fBbios-version\fR, \fBbios-release-date\fR,

\fBsystem-manufacturer\fR, \fBsystem-product-name\fR,

\fBsystem-version\fR, \fBsystem-serial-number\fR,

\fBsystem-uuid\fR, \fBsystem-family\fR,

\fBbaseboard-manufacturer\fR, \fBbaseboard-product-name\fR,

\fBbaseboard-version\fR, \fBbaseboard-serial-number\fR,

\fBbaseboard-asset-tag\fR, \fBchassis-manufacturer\fR,

\fBchassis-type\fR,

\fBchassis-version\fR, \fBchassis-serial-number\fR,

\fBchassis-asset-tag\fR, \fBprocessor-family\fR,

\fBprocessor-manufacturer\fR,

\fBprocessor-version\fR, \fBprocessor-frequency\fR.

Each keyword corresponds to a given \s-1DMI\s0 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.

\fBprocessor-version\fR on a multi-processor system).

If \fBKEYWORD\fR is not provided or not valid, a list of all valid

keywords is printed and

.B 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

.BR sysfs ,

typically from files under

.IR /sys/devices/virtual/dmi/id .

Most of these files are even readable by regular users.

.TP

.BR "-t" ", " "--type TYPE"

Only display the entries of type \fBTYPE\fR. \fBTYPE\fR can be either a

\s-1DMI\s0 type number, or a comma-separated list of type numbers, or a

keyword from the following list: \fBbios\fR, \fBsystem\fR,

\fBbaseboard\fR, \fBchassis\fR, \fBprocessor\fR, \fBmemory\fR,

\fBcache\fR, \fBconnector\fR, \fBslot\fR. 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 \fBTYPE\fR is not provided or not valid, a list of all valid keywords

is printed and

.B dmidecode

exits with an error.

.TP

.BR "-H" ", " "--handle HANDLE"

Only display the entry whose handle matches \fBHANDLE\fR.  \fBHANDLE\fR

is a 16-bit integer.

.TP

.BR "-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 \s-1ASCII\s0. This option is mainly useful for debugging.

.TP

.BR "  " "  " "--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 \fB--from-dump\fR

later.

.TP

.BR "  " "  " "--from-dump FILE"

Read the DMI data from a binary file previously generated using 

\fB--dump-bin\fR.

.TP

.BR "  " "  " "--no-sysfs"

Do not attempt to read DMI data from sysfs files. This is mainly useful for

debugging.

.TP

.BR "  " "  " "--oem-string N"

Only display the value of the \s-1OEM\s0 string number \fBN\fR. The first

\s-1OEM\s0 string has number 1. With special value "count", return the

number of OEM strings instead.

.TP

.BR "-h" ", " "--help"

Display usage information and exit

.TP

.BR "-V" ", " "--version"

Display the version and exit

.P

Options --string, --type, --dump-bin and --oem-string

determine the output format and are mutually exclusive.

.P

Please note in case of

.B 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.

.SH "DMI TYPES"

The \s-1SMBIOS\s0 specification defines the following \s-1DMI\s0 types:

.TS

r l

__

r l.

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

.TE

Additionally, type 126 is used for disabled entries and type 127 is an

end-of-table marker. Types 128 to 255 are for \s-1OEM\s0-specific data.

.B 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 \fB--type\fR.

Each keyword is equivalent to a list of type numbers:

.TS

l l

__

l l.

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

.TE

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

.IP \(bu "\w'\(bu'u+1n"

dmidecode --type 0 --type 13

.IP \(bu

dmidecode --type 0,13

.IP \(bu

dmidecode --type bios

.IP \(bu

dmidecode --type BIOS

.SH BINARY DUMP FILE FORMAT

The binary dump files generated by --dump-bin and read using --from-dump

are formatted as follows:

.IP \(bu "\w'\(bu'u+1n"

The SMBIOS or DMI entry point is located at offset 0x00.

It is crafted to hard-code the table address at offset 0x20.

.IP \(bu "\w'\(bu'u+1n"

The DMI table is located at offset 0x20.

.SH FILES

.I /dev/mem

.br

.I /sys/firmware/dmi/tables/smbios_entry_point

(Linux only)

.br

.I /sys/firmware/dmi/tables/DMI

(Linux only)

.SH BUGS

More often than not, information contained in the \s-1DMI\s0 tables is inaccurate,

incomplete or simply wrong.

.SH AUTHORS

Alan Cox, Jean Delvare

.SH "SEE ALSO"

.BR biosdecode (8),

.BR mem (4),

.BR ownership (8),

.BR vpddecode (8)